Publications by authors named "Jacek M Kwiecien"

42 Publications

Barriers to axonal regeneration after spinal cord injury: a current perspective.

Authors:
Jacek M Kwiecien

Neural Regen Res 2022 Jan;17(1):85-86

Department of Pathology and Molecular Medicine, Faculty of Health Sciences, McMaster University, Hamilton, Ontario, Canada.

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http://dx.doi.org/10.4103/1673-5374.314299DOI Listing
January 2022

Exercise Improves Cancer-free Survival and Healthspan in a Model of Radiation-induced Cancer.

Med Sci Sports Exerc 2021 May 28. Epub 2021 May 28.

School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, Canada Department of Pathology and Molecular Medicine, Faculty of Health Sciences, McMaster University, Hamilton, Canada Department of Cellular and Molecular Medicine, Centre on Neuromuscular Disease, and Regenerative Medicine Program, University of Ottawa, Ottawa, Canada.

Introduction: Radiation therapy increases the risk of secondary malignancy and morbidity in cancer survivors. The role of obesity and exercise training in modulating this risk is not well-understood. As such, we used a preclinical model of radiation-induced malignancy to investigate whether diet-induced obesity and/or endurance exercise training altered life-long survival, cancer incidence, and morbidity.

Methods: Male CBA mice were randomly divided into control diet/sedentary group (CTRL/SED), high fat diet (45% fat)/sedentary group (HFD/SED), control diet/exercise group (2-3 days/week; CTRL/EX), or high fat diet/exercise group (HFD/EX) groups, then exposed to whole-body radiation (3 Gy). Endpoint monitoring and pathology determined mortality and cancer incidence, respectively. Healthspan index, a measure of morbidity, was determined by a composite measure of ten anthropometric, metabolic, performance, and behavioral measures.

Results: Overall survival was higher in HFD/SED compared to CTRL/SED (p < 0.05). Risk of cancer-related mortality by 18 months post-radiation was 1.99 and 1.63 in HFD/SED compared to CTRL/EX (RR = 1.99; 95% CI, 1.20-3.31; p = 0.0081) and CTRL/SED (RR = 1.63; 95% CI, 1.06-2.49; p = 0.0250), respectively. The number of mice at endpoint with cancer was higher in HFD/SED compared to CTRL/EX and CTRL/SED (p < 0.05). Healthspan index was highest in CTRL/EX (score = +2.5), followed by HFD/EX (score = +1), and HFD/SED (score = -1) relative to CTRL/SED.

Conclusion: This work provides the basis for future preclinical studies investigating the dose-response relationship between exercise training and late effects of radiation therapy as well as the mechanisms responsible for these effects.
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http://dx.doi.org/10.1249/MSS.0000000000002711DOI Listing
May 2021

Imaging of Neurotrauma in Acute and Chronic Settings.

Curr Neuropharmacol 2021 May 16. Epub 2021 May 16.

Department of Neuroradiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona. United States.

Traumatic injuries of the brain and spinal cord are a significant source of mortality and long-term disability. A recent systematic study in a rat model of spinal cord injury (SCI) indicates severe, destructive, and very protracted inflammation as the key mechanism initiated by the massive injury involving the white matter. Although the severe inflammation is localized and counteracted by astrogliosis, it has a damaging effect on the blood vessels in the surrounding spinal cord, leading to persistent vasogenic edema. To evaluate these injuries, imaging of the brain and spinal cord plays a crucial role in the acute trauma work-up, allowing clinicians to quickly identify abnormalities that require immediate medical or surgical intervention or to exclude them from the work-up. Recently, anti-inflammatory agents have been shown to inhibit and accelerate the elimination of post-SCI inflammation in preclinical studies, and an exciting potential has arisen for the use of anti-inflammatory drugs in clinical studies to achieve neuroprotection (i.e., inhibition of destruction caused by inflammation) and to inhibit vasogenic edema in SCI, traumatic brain injury, and stroke. In both subacute and chronic settings, imaging can be a guide to therapy and provide important prognostic information. In this review, we discuss the imaging work-up and evolving imaging findings of neurotrauma in the acute and chronic setting, including conventional and advanced imaging techniques. As neuroimaging is the primary mode of diagnostic analysis in neurotrauma, it is a critical component in future clinical trials evaluating neuroprotective therapies.
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http://dx.doi.org/10.2174/1570159X19666210517114823DOI Listing
May 2021

The Pathogenesis of Neurotrauma Indicates Targets for Neuroprotective Therapies.

Authors:
Jacek M Kwiecien

Curr Neuropharmacol 2021 Jan 25. Epub 2021 Jan 25.

Department of Pathology and Molecular Medicine, faculty of Health Sciences, McMaster University, Room HSC 1U22D, 1280 Main Street West, Hamilton, ON. Canada.

The spinal cord injury (SCI) initiates an extraordinarily protracted disease with 3 phases; acute, inflammatory and resolution that are restricted to the cavity of injury (COI) or arachnoiditis by a unique CNS reaction against the severity of destructive inflammation. While the severity of inflammation involving the white matter is fueled by a potently immunogenic activity of damaged myelin, its sequestration in the COI and its continuity with the cerebrospinal fluid of the subdural space allows for anti-inflammatory therapeutics infused subdurally to inhibit phagocytic macrophage infiltration and thus provide neuroprotection. The role of astrogliosis in containing and ultimately in eliminating severe destructive inflammation post-trauma appears obvious but is not yet sufficiently understood to use in therapeutic neuroprotective and neuroregenerative strategies. An apparent anti-inflammatory activity of reactive astrocytes is paralleled by their active role in removing excess edema fluid in blood brain barrier damaged by inflammation. Recently elucidated pathogenesis of neurotrauma including SCI, traumatic brain injury (TBI) and of stroke, calls for the following principal therapeutic steps in its treatment leading to recovery of neurologic function: (1) inhibition and elimination of destructive inflammation from the COI with accompanying reduction of vasogenic edema, (2) insertion into the COI of a functional bridge supporting the crossing of regenerating axons, (3) enabling regeneration of axons to their original synaptic targets by a temporary safe removal of myelin in targeted areas of white matter, (4) in vivo, systematic monitoring of the consecutive therapeutic steps. The focus of this paper is on the therapeutic step 1.
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http://dx.doi.org/10.2174/1570159X19666210125153308DOI Listing
January 2021

Neurologic and Histologic Tests Used to Measure Neuroprotective Effectiveness of Virus-Derived Immune-Modulating Proteins.

Methods Mol Biol 2021 ;2225:227-239

Centers for Personalized Diagnostics and Immunotherapy, Vaccines and Virotherapy, Biodesign Institute, Arizona State University, Tempe, AZ, USA.

Severe inflammatory disease initiated by neurotrauma and stroke is of primary concern in these intractable pathologies as noted in recent studies and understanding of the pathogenesis of spinal cord injury (SCI) in the rat model. Successful anti-inflammatory treatments should result in neuroprotection and limit the loss of neurological function to injury caused by the initial damage. Continuous subdural infusion offers direct access to the cavity of injury (COI) that forms after balloon crush SCI deep in the spinal cord. Some anti-inflammatory compounds are not likely capable of crossing the blood-spinal cord barrier. Subdural infusion of myxoma virus-derived Serp-1, an anti-thrombotic/anti-thrombolytic, and also of M-T7, a chemokine inhibitor, improved the locomotor scores and pain sensation scores as well as reduced the numbers of macrophages in the COI by 50 and 80%, respectively, while intraperitoneal infusion of either protein had little effect. Injection of a chitosan hydrogel loaded with Serp-1 into the dorsal spinal column crush also resulted in improved neurological deficits and in reduction of the size of the crush lesion 4 weeks after injury. While neurological scores in a simplified hind-end (HE) locomotor test together with a toe-pinch withdrawal test demonstrated improvement in all balloon crush injury and dorsal spinal crush injury rats, a severe inflammation is induced by the injury indicating additional damage to the spinal cord. Thus neurological function testing can be contradictory, rather than corresponding, to the pathogenesis of SCI. The count of macrophages in the COI offers a precise, reliable method of measuring the effectiveness of a neuroprotective treatment of SCI in preclinical studies.
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http://dx.doi.org/10.1007/978-1-0716-1012-1_13DOI Listing
March 2021

Neuroprotective Effect of Subdural Infusion of Serp-1 in Spinal Cord Trauma.

Biomedicines 2020 Sep 23;8(10). Epub 2020 Sep 23.

Center for Personalized Diagnostics and Center for Immunotherapy, Vaccines and Virotherapy, Biodesign Institute, Arizona State University, Tempe, AZ 85287, USA.

Spinal cord injury (SCI) initiates a severe, destructive inflammation with pro-inflammatory, CD68+/CD163-, phagocytic macrophages infiltrating the area of necrosis and hemorrhage by day 3 and persisting for the next 16 weeks. Inhibition of macrophage infiltration of the site of necrosis that is converted into a cavity of injury (COI) during the first week post-SCI, should limit inflammatory damage, shorten its duration and result in neuroprotection. By sustained subdural infusion we administered Serp-1, a Myxoma virus-derived immunomodulatory protein previously shown to improve neurologic deficits and inhibit macrophage infiltration in the COI in rats with the balloon crush SCI. Firstly, in a 7 day long study, we determined that the optimal dose for macrophage inhibition was 0.2 mg/week. Then, we demonstrated that a continuous subdural infusion of Serp-1 for 8 weeks resulted in consistently accelerated lowering of pro-inflammatory macrophages in the COI and in their almost complete elimination similar to that previously observed at 16 weeks in untreated SCI rats. The macrophage count in the COI is a quantitative test directly related to the severity of destructive inflammation initiated by the SCI. This test has consistently demonstrated anti-inflammatory effect of Serp-1 interpreted as neuroprotection, the first and necessary step in a therapeutic strategy in neurotrauma.
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http://dx.doi.org/10.3390/biomedicines8100372DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7598159PMC
September 2020

The Role of Astrogliosis in Formation of the Syrinx in Spinal Cord Injury.

Curr Neuropharmacol 2021 ;19(2):294-303

Center for Personalized Diagnostics and Center for Immunotherapy, Vaccines and Virotherapy, Biodesign Institute, Arizona State University, Tempe, AZ, United States.

A massive localized trauma to the spinal cord results in complex pathologic events driven by necrosis and vascular damage which in turn leads to hemorrhage and edema. Severe, destructive and very protracted inflammatory response is characterized by infiltration by phagocytic macrophages of a site of injury which is converted into a cavity of injury (COI) surrounded by astroglial reaction mounted by the spinal cord. The tissue response to the spinal cord injury (SCI) has been poorly understood but the final outcome appears to be a mature syrinx filled with the cerebrospinal fluid with related neural tissue loss and permanent neurologic deficits. This paper reviews known pathologic mechanisms involved in the formation of the COI after SCI and discusses the integrative role of reactive astrogliosis in mechanisms involved in the removal of edema after the injury. A large proportion of edema fluid originating from the trauma and then from vasogenic edema related to persistent severe inflammation, may be moved into the COI in an active process involving astrogliosis and specifically over-expressed aquaporins.
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http://dx.doi.org/10.2174/1570159X18666200720225222DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8033977PMC
January 2021

A Cross-Reactive Small Protein Binding Domain Provides a Model to Study Off-Tumor CAR-T Cell Toxicity.

Mol Ther Oncolytics 2020 Jun 14;17:278-292. Epub 2020 Apr 14.

Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON L8S 4K1, Canada.

Tumor-targeted chimeric antigen receptor (CAR)-engineered T lymphocytes (CAR-T cells) have demonstrated striking clinical success, but their use has been associated with a constellation of toxicities. A better understanding of the pathogenesis of these toxicities is required to improve the safety profile of CAR-T cells. Herein, we describe a xenograft model of off-tumor CAR-T cell-associated toxicity. Human CAR-T cells targeted against HER2 using a small-protein binding domain induced acute, dose-dependent toxicities in mice. The inclusion of a CD28 or 4-1BB co-stimulatory domain in the CAR was required to produce toxicity; however, co-stimulation through CD28 was most toxic on a per-cell basis. CAR-T cell activation in the lungs and heart was associated with a systemic cytokine storm. The severity of observed toxicities was dependent upon the peripheral blood mononuclear cell (PBMC) donor used as a T cell source and paralleled the CD4-to-CD8 T cell ratio in the adoptive transfer product. CD4 CAR-T cells were determined to be the primary contributors to CAR-T cell-associated toxicity. However, donor-specific differences persisted after infusion of a purified CD4 CAR-T cell product, indicating a role for additional variables. This work highlights the contributions of CAR-T cell-intrinsic variables to the pathogenesis of off-tumor toxicity.
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http://dx.doi.org/10.1016/j.omto.2020.04.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7191649PMC
June 2020

Local Serpin Treatment via Chitosan-Collagen Hydrogel after Spinal Cord Injury Reduces Tissue Damage and Improves Neurologic Function.

J Clin Med 2020 Apr 23;9(4). Epub 2020 Apr 23.

Center for Personalized Diagnostics and Center for Immunotherapy, Vaccines and Virotherapy, Biodesign Institute, Arizona State University, Tempe, AZ 85287, USA.

Spinal cord injury (SCI) results in massive secondary damage characterized by a prolonged inflammation with phagocytic macrophage invasion and tissue destruction. In prior work, sustained subdural infusion of anti-inflammatory compounds reduced neurological deficits and reduced pro-inflammatory cell invasion at the site of injury leading to improved outcomes. We hypothesized that implantation of a hydrogel loaded with an immune modulating biologic drug, Serp-1, for sustained delivery after crush-induced SCI would have an effective anti-inflammatory and neuroprotective effect. Rats with dorsal column SCI crush injury, implanted with physical chitosan-collagen hydrogels (CCH) had severe granulomatous infiltration at the site of the dorsal column injury, which accumulated excess edema at 28 days post-surgery. More pronounced neuroprotective changes were observed with high dose (100 µg/50 µL) Serp-1 CCH implanted rats, but not with low dose (10 µg/50 µL) Serp-1 CCH. Rats treated with Serp-1 CCH implants also had improved motor function up to 20 days with recovery of neurological deficits attributed to inhibition of inflammation-associated tissue damage. In contrast, prolonged low dose Serp-1 infusion with chitosan did not improve recovery. Intralesional implantation of hydrogel for sustained delivery of the Serp-1 immune modulating biologic offers a neuroprotective treatment of acute SCI.
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http://dx.doi.org/10.3390/jcm9041221DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7230793PMC
April 2020

Deriving Immune Modulating Drugs from Viruses-A New Class of Biologics.

J Clin Med 2020 Mar 31;9(4). Epub 2020 Mar 31.

Center for Personalized Diagnostics, Biodesign Institute, Arizona State University, Tempe, AZ 85281, USA.

Viruses are widely used as a platform for the production of therapeutics. Vaccines containing live, dead and components of viruses, gene therapy vectors and oncolytic viruses are key examples of clinically-approved therapeutic uses for viruses. Despite this, the use of virus-derived proteins as natural sources for immune modulators remains in the early stages of development. Viruses have evolved complex, highly effective approaches for immune evasion. Originally developed for protection against host immune responses, viral immune-modulating proteins are extraordinarily potent, often functioning at picomolar concentrations. These complex viral intracellular parasites have "performed the R&D", developing highly effective immune evasive strategies over millions of years. These proteins provide a new and natural source for immune-modulating therapeutics, similar in many ways to penicillin being developed from mold or streptokinase from bacteria. Virus-derived serine proteinase inhibitors (serpins), chemokine modulating proteins, complement control, inflammasome inhibition, growth factors (e.g., viral vascular endothelial growth factor) and cytokine mimics (e.g., viral interleukin 10) and/or inhibitors (e.g., tumor necrosis factor) have now been identified that target central immunological response pathways. We review here current development of virus-derived immune-modulating biologics with efficacy demonstrated in pre-clinical or clinical studies, focusing on pox and herpesviruses-derived immune-modulating therapeutics.
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http://dx.doi.org/10.3390/jcm9040972DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7230489PMC
March 2020

Prolonged inflammation leads to ongoing damage after spinal cord injury.

PLoS One 2020 19;15(3):e0226584. Epub 2020 Mar 19.

Centers for Personalized Diagnostics and Immunotherapy, Vaccines and Virotherapy, Biodesign Institute, Arizona State University, Tempe, Arizona, United States of America.

The pathogenesis of spinal cord injury (SCI) remains poorly understood and treatment remains limited. Emerging evidence indicates that post-SCI inflammation is severe but the role of reactive astrogliosis not well understood given its implication in ongoing inflammation as damaging or neuroprotective. We have completed an extensive systematic study with MRI, histopathology, proteomics and ELISA analyses designed to further define the severe protracted and damaging inflammation after SCI in a rat model. We have identified 3 distinct phases of SCI: acute (first 2 days), inflammatory (starting day 3) and resolution (>3 months) in 16 weeks follow up. Actively phagocytizing, CD68+/CD163- macrophages infiltrate myelin-rich necrotic areas converting them into cavities of injury (COI) when deep in the spinal cord. Alternatively, superficial SCI areas are infiltrated by granulomatous tissue, or arachnoiditis where glial cells are obliterated. In the COI, CD68+/CD163- macrophage numbers reach a maximum in the first 4 weeks and then decline. Myelin phagocytosis is present at 16 weeks indicating ongoing inflammatory damage. The COI and arachnoiditis are defined by a wall of progressively hypertrophied astrocytes. MR imaging indicates persistent spinal cord edema that is linked to the severity of inflammation. Microhemorrhages in the spinal cord around the lesion are eliminated, presumably by reactive astrocytes within the first week post-injury. Acutely increased levels of TNF-alpha, IL-1beta, IFN-gamma and other pro-inflammatory cytokines, chemokines and proteases decrease and anti-inflammatory cytokines increase in later phases. In this study we elucidated a number of fundamental mechanisms in pathogenesis of SCI and have demonstrated a close association between progressive astrogliosis and reduction in the severity of inflammation.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0226584PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7081990PMC
May 2020

Modifying the Organ Matrix Pre-engraftment: A New Transplant Paradigm?

Trends Mol Med 2019 07 17;25(7):626-639. Epub 2019 May 17.

The Center for Personalized Diagnostics, The Biodesign Institute, Arizona State University, Tempe, AZ, USA; The Center for Immunotherapy, Vaccines and Virotherapy, The Biodesign Institute, Arizona State University, Tempe, AZ, USA; Division of Cardiovascular Medicine, University of Florida, Gainesville, FL, USA; Division of Rheumatology, Department of Medicine, University of Florida, Gainesville, FL, USA; Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL, USA; Department of Medicine, St Joseph's Hospital, Dignity Health, Phoenix, AZ, USA. Electronic address:

The availability of solid organs for transplantation remains low and there is a substantial need for methods to preserve the viability of grafted tissues. Suppression of solid-organ transplant rejection has traditionally focused on highly effective T cell inhibitors that block host immune lymphocyte responses. However, persistent and destructive innate and acquired immune reactions remain difficult to treat, causing late graft loss. Pretreatment of grafts to reduce organ rejection provides an alternate strategy. Approaches using antithrombotics, stem cells, genetic modifications, modulation of infrastructural components (connective tissue, CT; glycocalyx) of donor organs, and engineering of new organs are under investigation. We discuss here new approaches to modify transplanted organs prior to engraftment as a method to reduce rejection, focusing on the CT matrix.
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http://dx.doi.org/10.1016/j.molmed.2019.04.002DOI Listing
July 2019

Myxoma virus derived immune modulating proteins, M-T7 and Serp-1, reduce early inflammation after spinal cord injury in the rat model.

Folia Neuropathol 2019 ;57(1):41-50

Spinal cord injury (SCI)-initiated inflammation was treated with anti-inflammatory reagents. We compared local spinal cord or intraperitoneal infusion of two Myxoma virus derived immune modulating proteins, Serp-1 and M-T7, with dexamethasone (DEX). Hemorrhage and necrosis after SCI initiate a complex pathogenesis dominated by early, severe and highly destructive inflammatory macrophage infiltration. We examined sustained, 7-day, subdural infusion of either M-T7, a chemokine modulator or Serp-1, a plasminogen activator and factor inhibitor. Mature male rats had epidural balloon crush SCI and sustained subdural infusion of Serp-1, M-T7, DEX or saline for 7 days via the osmotic pump. A separate group of rats with SCI had intra-peritoneal infusion. Clinical evaluation included endpoint monitoring with body weight, hemorrhagic cystitis and bilateral toe pinch response. Sections of the spinal cord were analyzed histologically and macrophage numbers counted by standardized protocol in the cavity of injury (COI). While the rats administered DEX demonstrated substantial body weight loss, dehydration and dermal atrophy consistent with steroid toxicity, rats infused with Serp-1 and M-T7 had no toxicity. Serp-1 improved withdrawal responses. Subdural infusion of Serp-1, M-T7 and DEX significantly reduced numbers of phagocytic, CD68-positive macrophages. With intraperitoneal infusion only M-T7 reduced macrophage counts, Serp-1 showed only a trend. Local infusion of highly active immune modulating proteins; Serp-1 and M-T7, targeting serine protease and chemokine pathways demonstrated excellent potential for neuroprotection after severe SCI in a rat model, without adverse side effects. Sustained subdural infusion offers an alternative route of administration for treatment of SCI.
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http://dx.doi.org/10.5114/fn.2019.83830DOI Listing
August 2019

Cross-linked cellulose nanocrystal aerogels as viable bone tissue scaffolds.

Acta Biomater 2019 03 30;87:152-165. Epub 2019 Jan 30.

Department of Material Science and Engineering, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4L7, Canada; School of Biomedical Engineering, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4L7, Canada. Electronic address:

Chemically cross-linked cellulose nanocrystal (CNC) aerogels possess many properties beneficial for bone tissue scaffolding applications. CNCs were extracted using sulfuric acid or phosphoric acid, to produce CNCs with sulfate and phosphate half-ester surface groups, respectively. Hydrazone cross-linked aerogels fabricated from the two types of CNCs were investigated using scanning electron microscopy, X-ray micro-computed tomography, X-ray photoelectron spectroscopy, nitrogen sorption isotherms, and compression testing. CNC aerogels were evaluatedin vitrowith osteoblast-like Saos-2 cells and showed an increase in cell metabolism up to 7 days while alkaline phosphatase assays revealed that cells maintained their phenotype. All aerogels demonstrated hydroxyapatite growth over 14 days while submerged in simulated body fluid solution with a 0.1 M CaCl pre-treatment. Sulfated CNC aerogels slightly outperformed phosphated CNC aerogels in terms of compressive strength and long-term stability in liquid environments, and were implanted into the calvarian bone of adult male Long Evans rats. Compared to controls at 3 and 12 week time points, sulfated CNC aerogels showed increased bone volume fraction of 33% and 50%, respectively, compared to controls, and evidence of osteoconductivity. These results demonstrate that cross-linked CNC aerogels are flexible, porous and effectively facilitate bone growth after they are implanted in bone defects. STATEMENT OF SIGNIFICANCE: Due to the potential complications associated with autografts, there is a need for synthetic bone tissue scaffolds. Here, we report a new naturally-based aerogel material for bone regeneration made solely from chemically cross-linked cellulose nanocrystals (CNC). These highly porous CNC aerogels were shown to promote the proliferation of bone-like cells and support the growth of hydroxyapatite on their surface in vitro. The first in vivo study on these materials was conducted in rats and showed their osteconductive properties and an increase in bone volume up to 50% compared to sham sites. This study demonstrates the potential of using functionalized cellulose nanocrystals as the basis for aerogel scaffolds for bone tissue engineering.
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http://dx.doi.org/10.1016/j.actbio.2019.01.049DOI Listing
March 2019

Age-related deficits in intracortical myelination in young adults with bipolar disorder type I

J Psychiatry Neurosci 2019 03;44(2):79-88

From the Graduate Student, MiNDS Neuroscience Graduate Program, McMaster University, Hamilton, ON (Sehmbi, Rowley); the Mood Disorders Program, Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON (Minuzzi, Kapczinski, Frey); the Women’s Health Concerns Clinic, St. Joseph’s Healthcare, Hamilton, ON (Minuzzi, Frey); the Department of Pathology and Molecular Medicine, M. deGroote School of Medicine, McMaster University, Hamilton, ON (Kwiecien); the Department of Psychology, Neuroscience, and Behaviour, McMaster University, Hamilton, ON (Bock); and the Department of Clinical Pathomorphology, Medical University of Lublin, Poland (Kwiecien).

Background: Previous studies have implicated white-matter-related changes in the pathophysiology of bipolar disorder. However, most of what is known is derived from in vivo subcortical white-matter imaging or postmortem studies. In this study, we investigated whole-brain intracortical myelin (ICM) content in people with bipolar disorder type I and controls.

Methods: Between Sept. 1, 2014, and Jan. 31, 2017, we used a 3 T General Electric scanner to collect T1-weighted images in 45 people with bipolar disorder type I and 60 controls aged 17 to 45 years using an optimized sequence that was sensitive to ICM content. We analyzed images using a surfacebased approach. We used general linear models with quadratic age terms to examine the signal trajectory of ICM across the age range.

Results: In healthy controls, the T1-weighted signal followed an inverted-U trajectory over age; in people with bipolar disorder type I, the association between ICM and age followed a flat trajectory (p < 0.05, Bonferroni corrected). Exploratory analyses showed that ICM signal intensity was associated with duration of illness, age of onset, and anticonvulsant and antipsychotic use in people with bipolar disorder type I (p < 0.05, uncorrected).

Limitations: Because of the cross-sectional nature of the study, we were unable to comment on whether the effects were due to dysmyelination or demyelination in bipolar disorder.

Conclusion: This foundational study is, to our knowledge, the first to show global age-related deficits in ICM maturation throughout the cortex in bipolar disorder. Considering the impact of myelination on the maintenance of neural synchrony and the integrity of neural connections, this work may help us better understand the cognitive and behavioural deficits seen in bipolar disorder.
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http://dx.doi.org/10.1503/jpn.170220DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6397039PMC
March 2019

BMI1 is a therapeutic target in recurrent medulloblastoma.

Oncogene 2019 03 22;38(10):1702-1716. Epub 2018 Oct 22.

Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, L8S 4L8, Canada.

Medulloblastoma (MB) is the most frequent malignant pediatric brain tumor, representing 20% of newly diagnosed childhood central nervous system malignancies. Although advances in multimodal therapy yielded a 5-year survivorship of 80%, MB still accounts for the leading cause of childhood cancer mortality. In this work, we describe the epigenetic regulator BMI1 as a novel therapeutic target for the treatment of recurrent human Group 3 MB, a childhood brain tumor for which there is virtually no treatment option beyond palliation. Current clinical trials for recurrent MB patients based on genomic profiles of primary, treatment-naive tumors will provide limited clinical benefit since recurrent metastatic MBs are highly genetically divergent from their primary tumor. Using a small molecule inhibitor against BMI1, PTC-028, we were able to demonstrate complete ablation of self-renewal of MB stem cells in vitro. When administered to mice xenografted with patient tumors, we observed significant reduction in tumor burden in both local and metastatic compartments and subsequent increased survival, without neurotoxicity. Strikingly, serial in vivo re-transplantation assays demonstrated a marked reduction in tumor initiation ability of recurrent MB cells upon re-transplantation of PTC-028-treated cells into secondary recipient mouse brains. As Group 3 MB is often metastatic and uniformly fatal at recurrence, with no current or planned trials of targeted therapy, an efficacious targeted agent would be rapidly transitioned to clinical trials.
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http://dx.doi.org/10.1038/s41388-018-0549-9DOI Listing
March 2019

Cancer pain and neuropathic pain are associated with A β sensory neuronal plasticity in dorsal root ganglia and abnormal sprouting in lumbar spinal cord.

Mol Pain 2018 Jan-Dec;14:1744806918810099. Epub 2018 Oct 16.

1 Michael G. DeGroote Institute for Pain Research and Care, McMaster University, Hamilton, ON, Canada.

Evidence suggests that there are both nociceptive and neuropathic components of cancer-induced pain. We have observed that changes in intrinsic membrane properties and excitability of normally non-nociceptive Aβ sensory neurons are consistent in rat models of peripheral neuropathic pain and cancer-induced pain. This has prompted a comparative investigation of the intracellular electrophysiological characteristics of sensory neurons and of the ultrastructural morphology of the dorsal horn in rat models of neuropathic pain and cancer-induced pain. Neuropathic pain model rats were induced with a polyethylene cuff implanted around a sciatic nerve. Cancer-induced pain model rats were induced with mammary rat metastasis tumour-1 rat breast cancer or MATLyLu rat prostate cancer cells implanted into the distal epiphysis of a femur. Behavioural evidence of nociception was detected using von Frey tactile assessment. Aβ-fibre low threshold mechanoreceptor neurons in both cancer-induced pain and neuropathic pain models exhibited slower dynamics of action potential genesis, including a wider action potential duration and lower action potential amplitude compared to those in control animals. Enhanced excitability of Aβ-fibre low threshold mechanoreceptor neurons was also observed in cancer-induced pain and neuropathic pain models. Furthermore, both cancer-induced pain and neuropathic pain models showed abundant abnormal axonal sprouting in bundles of myelinated axons in the ipsilateral spinal laminae IV and V. The patterns of changes show consistency between rat models of cancer-induced pain and neuropathic pain. These findings add to the body of evidence that animal models of cancer-induced pain and neuropathic pain share features that may contribute to the peripheral and central sensitization and tactile hypersensitivity in both pain states.
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http://dx.doi.org/10.1177/1744806918810099DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6243409PMC
February 2019

Methods for Assessing Serpins as Neuroprotective Therapeutics.

Authors:
Jacek M Kwiecien

Methods Mol Biol 2018 ;1826:223-235

Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada.

As the systematic work on the pathogenesis of the white matter injury in the spinal cord models progresses, it becomes obvious that a severe and extraordinarily protracted, destructive inflammation follows the initial injury. Appropriate anti-inflammatory therapies of sufficient duration should not only inhibit but also lead to the elimination of this destructive inflammation, thus resulting in neuroprotection of the spinal cord tissue and a greater preservation of the neurologic function. While dexamethasone, a powerful, anti-inflammatory steroid analog administered continuously by subdural infusion for 7 days inhibited severe macrophage infiltration in the cavity of injury, the dose used was remarkably toxic. A 2-week-long infusion of lower doses of dexamethasone resulted in dose-dependent inhibition of macrophage infiltration and was better tolerated by the rats, but it became evident that a much longer duration of subdural administration of a powerful anti-inflammatory drug is required to eliminate myelin-rich, necrotic debris from the cavity and synthetic steroids such as dexamethasone, and methylprednisolone may be too toxic for this application. Therefore, nontoxic but powerful anti-inflammatory compounds are required for neuroprotective treatment of the spinal cord injury (SCI) and also brain trauma and stroke where the massive injury to the white matter occurs. Serpins have been associated with neurological damage. The mammalian serpin neuroserpin (SERPINI1) is reported to act in a protective manner after cerebrospinal infarction. The serine protease, tissue-type plasminogen activator (tPA), and the serpin plasminogen activator inhibitor (PAI-1, SERPINE1) are both upregulated at sites of central nervous system damage. In preliminary studies, subdural infusion of the myxomaviral serpin, Serp-1, resulted in the powerful inhibition of the macrophage infiltration of the cavity of injury, comparable to the inhibition by high dose of dexamethasone that has proven to be unduly toxic. Nontoxic, yet powerful neuroprotective, anti-inflammatory effects of Serp-1 may indicate this serpin protein as a potential attractive compound to treat SCI and similar syndromes involving massive injury to the white matter such as brain trauma and stroke. Novel methods of drug delivery, chronic subdural infusion, and novel analytic methods to measure the effectiveness of the neuroprotective serpin treatments are discussed in this chapter.
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http://dx.doi.org/10.1007/978-1-4939-8645-3_15DOI Listing
March 2019

The chimeric TAC receptor co-opts the T cell receptor yielding robust anti-tumor activity without toxicity.

Nat Commun 2018 08 3;9(1):3049. Epub 2018 Aug 3.

Department of Pathology and Molecular Medicine, McMaster University, 1280 Main St W, Hamilton, ON, L8S 4L8, Canada.

Engineering T cells with chimeric antigen receptors (CARs) is an effective method for directing T cells to attack tumors, but may cause adverse side effects such as the potentially lethal cytokine release syndrome. Here the authors show that the T cell antigen coupler (TAC), a chimeric receptor that co-opts the endogenous TCR, induces more efficient anti-tumor responses and reduced toxicity when compared with past-generation CARs. TAC-engineered T cells induce robust and antigen-specific cytokine production and cytotoxicity in vitro, and strong anti-tumor activity in a variety of xenograft models including solid and liquid tumors. In a solid tumor model, TAC-T cells outperform CD28-based CAR-T cells with increased anti-tumor efficacy, reduced toxicity, and faster tumor infiltration. Intratumoral TAC-T cells are enriched for Ki-67 CD8 T cells, demonstrating local expansion. These results indicate that TAC-T cells may have a superior therapeutic index relative to CAR-T cells.
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http://dx.doi.org/10.1038/s41467-018-05395-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6076291PMC
August 2018

Loss of Kaiso expression in breast cancer cells prevents intra-vascular invasion in the lung and secondary metastasis.

PLoS One 2017 7;12(9):e0183883. Epub 2017 Sep 7.

Department of Biology, LSB 331, McMaster University, Hamilton, Ontario, Canada.

The metastatic activity of breast carcinomas results from complex genetic changes in epithelial tumor cells and accounts for 90% of deaths in affected patients. Although the invasion of the local lymphatic vessels and veins by malignant breast tumor cells and their subsequent metastasis to the lung, has been recognized, the mechanisms behind the metastatic activity of breast tumor cells to other distal organs and the pathogenesis of metastatic cancer are not well understood. In this study, we utilized derivatives of the well-established and highly metastatic triple negative breast cancer (TNBC) cell line MDA-MB-231 (MDA-231) to study breast tumor metastasis in a mouse model. These MDA-231 derivatives had depleted expression of Kaiso, a POZ-ZF transcription factor that is highly expressed in malignant, triple negative breast cancers. We previously reported that Kaiso depletion attenuates the metastasis of xenografted MDA-231 cells. Herein, we describe the pathological features of the metastatic activity of parental (Kaisopositive) versus Kaisodepleted MDA-231 cells. Both Kaisopositive and Kaisodepleted MDA-231 cells metastasized from the original tumor in the mammary fat pad to the lung. However, while Kaisopositive cells formed large masses in the lung parenchyma, invaded large pulmonary blood vessels and formed secondary metastases and large tumors in the distal organs, Kaisodepleted cells metastasized only to the lung where they formed small metastatic lesions. Importantly, intravascular invasion and secondary metastases in distal organs were not observed in mice xenografted with Kaisodepleted cells. It thus appears that the lung may constitute a barrier for less invasive breast tumors such as the Kaisodepleted TNBC cells; this barrier may limit tumor growth and prevents Kaisodepleted TNBC cells from invading the pulmonary blood vessels and forming secondary metastases in distal organs.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0183883PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5589175PMC
October 2017

Osseointegration of a 3D Printed Stemmed Titanium Dental Implant: A Pilot Study.

Int J Dent 2017 19;2017:5920714. Epub 2017 Nov 19.

Department of Materials Science and Engineering, McMaster University, Hamilton, ON, Canada.

In this pilot study, a 3D printed Grade V titanium dental implant with a novel dual-stemmed design was investigated for its biocompatibility in vivo. Both dual-stemmed ( = 12) and conventional stainless steel conical ( = 4) implants were inserted into the tibial metaphysis of New Zealand white rabbits for 3 and 12 weeks and then retrieved with the surrounding bone, fixed, dehydrated, and embedded into epoxy resin. The implants were analyzed using correlative histology, microcomputed tomography, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The histological presence of multinucleated osteoclasts and cuboidal osteoblasts revealed active bone remodeling in the stemmed implant starting at 3 weeks and by 12 weeks in the conventional implant. Bone-implant contact values indicated that the stemmed implants supported bone growth along the implant from the coronal crest at both 3- and 12-week time periods and showed bone growth into microporosities of the 3D printed surface after 12 weeks. In some cases, new bone formation was noted in between the stems of the device. Conventional implants showed mechanical interlocking but did have indications of stress cracking and bone debris. This study demonstrates the comparable biocompatibility of these 3D printed stemmed implants in rabbits up to 12 weeks.
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http://dx.doi.org/10.1155/2017/5920714DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5733992PMC
November 2017

Kynurenic Acid Induces Impairment of Oligodendrocyte Viability: On the Role of Glutamatergic Mechanisms.

Neurochem Res 2017 Mar 21;42(3):838-845. Epub 2016 Jul 21.

Department of Experimental and Clinical Pharmacology, Medical University, Lublin, Poland.

Kynurenic acid (KYNA) is an end stage product of tryptophan metabolism with a variety of functions in the human body, both in the central nervous system (CNS) and in other organs. Although its activity in the human brain has been widely studied and effects on neural cells were emphasized, the effect of KYNA on oligodendroglial cells remains unknown. Present study aims at describing the activity of high concentration of KYNA in OLN-93 cells. The inhibition of OLN-93 oligodendrocytes viability by KYNA in a medium with reduced serum concentration has been demonstrated. Although decreased metabolic activity of KYNA treated OLN-93 cells was shown, the cells proliferation was not altered. KYNA treatment did not alter morphology as well as expression level of cell cycle and proliferation regulating proteins. Furthermore, glutamate receptor antagonists and agonists did not alter the inhibitory effect of KYNA on viability of OLN-93 oligodendrocytes. This study contributes to the elucidation of effects of KYNA on oligodendrocytes in vitro, yet further analyses are necessary to explain the mechanisms behind the damage and loss of myelin sheaths.
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http://dx.doi.org/10.1007/s11064-016-2009-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5357470PMC
March 2017

Differences in iron and manganese concentration may confound the measurement of myelin from R1 and R2 relaxation rates in studies of dysmyelination.

NMR Biomed 2016 07 26;29(7):985-98. Epub 2016 May 26.

Psychology, Neuroscience and Behaviour, McMaster University, Hamilton, ON, Canada.

A model of dysmyelination, the Long Evans Shaker (les) rat, was used to study the contribution of myelin to MR tissue properties in white matter. A large region of white matter was identified in the deep cerebellum and was used for measurements of the MR relaxation rate constants, R1  = 1/T1 and R2  = 1/T2 , at 7 T. In this study, R1 of the les deep cerebellar white matter was found to be 0.55 ± 0.08 s (-1) and R2 was found to be 15 ± 1 s(-1) , revealing significantly lower R1 and R2 in les white matter relative to wild-type (wt: R1  = 0.69 ± 0.05 s(-1) and R2  = 18 ± 1 s(-1) ). These deviated from the expected ΔR1 and ΔR2 values, given a complete lack of myelin in the les white matter, derived from the literature using values of myelin relaxivity, and we suspect that metals could play a significant role. The absolute concentrations of the paramagnetic transition metals iron (Fe) and manganese (Mn) were measured by a micro-synchrotron radiation X-ray fluorescence (μSRXRF) technique, with significantly greater Fe and Mn in les white matter than in wt (in units of μg [metal]/g [wet weight tissue]: les: Fe concentration,19 ± 1; Mn concentration, 0.71 ± 0.04; wt: Fe concentration,10 ± 1; Mn concentration, 0.47 ± 0.04). These changes in Fe and Mn could explain the deviations in R1 and R2 from the expected values in white matter. Although it was found that the influence of myelin still dominates R1 and R2 in wt rats, there were non-negligible changes in the contribution of the metals to relaxation. Although there are already problems with the estimation of myelin from R1 and R2 changes in disease models with pathology that also affects the relaxation rate constants, this study points to a specific pitfall in the estimation of changes in myelin in diseases or models with disrupted concentrations of paramagnetic transition metals. Copyright © 2016 John Wiley & Sons, Ltd.
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http://dx.doi.org/10.1002/nbm.3549DOI Listing
July 2016

Cigarette Smoke Attenuates the Nasal Host Response to Streptococcus pneumoniae and Predisposes to Invasive Pneumococcal Disease in Mice.

Infect Immun 2016 05 22;84(5):1536-1547. Epub 2016 Apr 22.

Department of Pathology and Molecular Medicine, McMaster Immunology Research Centre, McMaster University, Hamilton, Ontario, Canada

Streptococcus pneumoniae is a leading cause of invasive bacterial infections, with nasal colonization an important first step in disease. While cigarette smoking is a strong risk factor for invasive pneumococcal disease, the underlying mechanisms remain unknown. This is partly due to a lack of clinically relevant animal models investigating nasal pneumococcal colonization in the context of cigarette smoke exposure. We present a model of nasal pneumococcal colonization in cigarette smoke-exposed mice and document, for the first time, that cigarette smoke predisposes to invasive pneumococcal infection and mortality in an animal model. Cigarette smoke increased the risk of bacteremia and meningitis without prior lung infection. Mechanistically, deficiency in interleukin 1α (IL-1α) or platelet-activating factor receptor (PAFR), an important host receptor thought to bind and facilitate pneumococcal invasiveness, did not rescue cigarette smoke-exposed mice from invasive pneumococcal disease. Importantly, we observed cigarette smoke to attenuate nasal inflammatory mediator expression, particularly that of neutrophil-recruiting chemokines, normally elicited by pneumococcal colonization. Smoking cessation during nasal pneumococcal colonization rescued nasal neutrophil recruitment and prevented invasive disease in mice. We propose that cigarette smoke predisposes to invasive pneumococcal disease by suppressing inflammatory processes of the upper respiratory tract. Given that smoking prevalence remains high worldwide, these findings are relevant to the continued efforts to reduce the invasive pneumococcal disease burden.
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http://dx.doi.org/10.1128/IAI.01504-15DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4862724PMC
May 2016

An in vivo model of anti-inflammatory activity of subdural dexamethasone following the spinal cord injury.

Neurol Neurochir Pol 2016 27;50(1):7-15. Epub 2015 Nov 27.

Department of Anaesthesiology and Intensive Therapy, Medical University of Lublin, Lublin, Poland. Electronic address:

Current therapies to limit the neural tissue destruction following the spinal cord injury are not effective. Our recent studies indicate that the injury to the white matter of the spinal cord results in a severe inflammatory response where macrophages phagocytize damaged myelin and the fluid-filled cavity of injury extends in size with concurrent and irreversible destruction of the surrounding neural tissue over several months. We previously established that a high dose of 4mg/rat of dexamethasone administered for 1 week via subdural infusion remarkably lowers the numbers of infiltrating macrophages leaving large amounts of un-phagocytized myelin debris and therefore inhibits the severity of inflammation and related tissue destruction. But this dose was potently toxic to the rats. In the present study the lower doses of dexamethasone, 0.125-2.0mg, were administered via the subdural infusion for 2 weeks after an epidural balloon crush of the mid-thoracic spinal cord. The spinal cord cross-sections were analyzed histologically. Levels of dexamethasone used in the current study had no systemic toxic effect and limited phagocytosis of myelin debris by macrophages in the lesion cavity. The subdural infusion with 0.125-2.0mg dexamethasone over 2 week period did not eliminate the inflammatory process indicating the need for a longer period of infusion to do so. However, this treatment has probably lead to inhibition of the tissue destruction by the severe, prolonged inflammatory process.
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http://dx.doi.org/10.1016/j.pjnns.2015.10.006DOI Listing
June 2016

Prolonged Subdural Infusion of Kynurenic Acid Is Associated with Dose-Dependent Myelin Damage in the Rat Spinal Cord.

PLoS One 2015 12;10(11):e0142598. Epub 2015 Nov 12.

Department of Experimental and Clinical Pharmacology, Medical University, Lublin, Poland.

Background: Kynurenic acid (KYNA) is the end stage metabolite of tryptophan produced mainly by astrocytes in the central nervous system (CNS). It has neuroprotective activities but can be elevated in the neuropsychiatric disorders. Toxic effects of KYNA in the CNS are unknown. The aim of this study was to assess the effect of the subdural KYNA infusion on the spinal cord in adult rats.

Methods: A total of 42 healthy adult rats were randomly assigned into six groups and were infused for 7 days with PBS (control) or 0.0002 pmol/min, 0.01 nmol/min, 0.1 nmol/min, 1 nmol/min, and 10 nmol/min of KYNA per 7 days. The effect of KYNA on spinal cord was determined using histological and electron microscopy examination. Myelin oligodendrocyte glycoprotein (MOG) was measured in the blood serum to assess a degree of myelin damage.

Result: In all rats continuous long-lasting subdural KYNA infusion was associated with myelin damage and myelin loss that was increasingly widespread in a dose-depended fashion in peripheral, sub-pial areas. Damage to myelin sheaths was uniquely related to the separation of lamellae at the intraperiod line. The damaged myelin sheaths and areas with complete loss of myelin were associated with limited loss of scattered axons while vast majority of axons in affected areas were morphologically intact. The myelin loss-causing effect of KYNA occurred with no necrosis of oligodendrocytes, with locally severe astrogliosis and no cellular inflammatory response. Additionally, subdural KYNA infusion increased blood MOG concentration. Moreover, the rats infused with the highest doses of KYNA (1 and 10 nmol/min) demonstrated adverse neurological signs including weakness and quadriplegia.

Conclusions: We suggest, that subdural infusion of high dose of KYNA can be used as an experimental tool for the study of mechanisms of myelin damage and regeneration. On the other hand, the administration of low, physiologically relevant doses of KYNA may help to discover the role of KYNA in control of physiological myelination process.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0142598PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4643054PMC
June 2016

T Cells Engineered With Chimeric Antigen Receptors Targeting NKG2D Ligands Display Lethal Toxicity in Mice.

Mol Ther 2015 Oct 30;23(10):1600-10. Epub 2015 Jun 30.

Department of Pathology and Molecular Medicine, McMaster Immunology Research Centre, McMaster University, Hamilton, Ontario, Canada.

Ligands for the NKG2D receptor are overexpressed on tumors, making them interesting immunotherapy targets. To assess the tumoricidal properties of T cells directed to attack NKG2D ligands, we engineered murine T cells with two distinct NKG2D-based chimeric antigen receptors (CARs): (i) a fusion between the NKG2D receptor and the CD3ζ chain and (ii) a conventional second-generation CAR, where the extracellular domain of NKG2D was fused to CD28 and CD3ζ. To enhance the CAR surface expression, we also engineered T cells to coexpress DAP10. In vitro functionality and surface expression levels of all three CARs was greater in BALB/c T cells than C57BL/6 T cells, indicating strain-specific differences. Upon adoptive transfer of NKG2D-CAR-T cells into syngeneic animals, we observed significant clinical toxicity resulting in morbidity and mortality. The severity of these toxicities varied between the CAR configurations and paralleled their in vitro NKG2D surface expression. BALB/c mice were more sensitive to these toxicities than C57BL/6 mice, consistent with the higher in vitro functionality of BALB/c T cells. Treatment with cyclophosphamide prior to adoptive transfer exacerbated the toxicity. We conclude that while NKG2D ligands may be useful targets for immunotherapy, the pursuit of NKG2D-based CAR-T cell therapies should be undertaken with caution.
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http://dx.doi.org/10.1038/mt.2015.119DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4817919PMC
October 2015

Quantitative MRI in a non-surgical model of cervical spinal cord injury.

NMR Biomed 2015 Aug 4;28(8):925-36. Epub 2015 Jun 4.

Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada.

Quantitative T2 (qT2), diffusion tensor imaging (DTI), and histology were used to investigate a cervical model of spinal cord injury (SCI) in the rat. While quantitative MRI can significantly increase the specificity in the presence of pathology, it must be validated for each type of injury or disease. In the case of traumatic SCI most models are difficult to image, either due to the location of the injury, or as a result of damage to surrounding tissues resulting from invasive surgical procedures. In this study a non-surgical cervical model of SCI, produced using a combination of focused ultrasound and microbubbles, was used to produce pathology similar to that seen in models of contusive and compressive injuries. qT2 and DTI were performed at 24 h and 1 and 2 weeks following injury, and compared with H&E and luxol fast blue histology. In the injured spinal cord, in addition to intra/extracellular (I/E) water and myelin water in white matter, qT2 revealed a large component with very short T2 of about 3 ms, which was highly correlated with the presence of hemorrhage in both gray and white matter at 24 h, and with the presence of hemosiderin in gray matter at 2 weeks following injury. The T2 of the I/E water peak was also elevated at 24 h in both gray and white matter, which was correlated with the presence of vacuolation/edema on histology. Cystic cavities were only seen at the 1 or 2 week timepoints, and were correlated with the presence of a water peak with T2  > 250 ms. No significant changes in diffusivity parameters were observed. Pathologies were often co-occurring, with opposite effects on the average T2 in a given voxel, reducing the visibility of injured tissue on standard T2 -weighted MR images.
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http://dx.doi.org/10.1002/nbm.3326DOI Listing
August 2015

A non-surgical model of cervical spinal cord injury induced with focused ultrasound and microbubbles.

J Neurosci Methods 2014 Sep 23;235:92-100. Epub 2014 Jun 23.

Department of Medical Biophysics, University of Toronto, 172 St George Street, Toronto, ON M5R 0A3, Canada; Physical Sciences, Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada. Electronic address:

Background: The most commonly used animal models of spinal cord injury (SCI) involve surgical exposure of the dorsal spinal cord followed by transection, contusion or compression. This high level of invasiveness often requires significant post-operative care and can limit post-operative imaging, as the surgical incision site can interfere with coil placement for magnetic resonance imaging (MRI) during the acute phase of SCI. While these models are considered to be similar to human SCI, they do not occur in a closed vertebral system as do the majority of human injuries.

New Method: Here we describe a novel, non-surgical model of SCI in the rat using MR-guided focused ultrasound (FUS) in combination with intravenous injection of microbubbles, applied to the cervical spinal cord.

Results: The injury was well-tolerated and resulted in cervical spinal cord damage in 60% of the animals. The area of Gd-enhancement immediately post-FUS and area of signal abnormality at 24h were correlated with the degree of injury. The extent of injury was easily visualized with T2-weighted MRI and was confirmed using histology.

Comparison With Existing Method(s): Pathology was similar to that seen in other rat models of direct spinal cord contusion and compression. Unlike these methods, FUS is non-surgical and has lower mortality than seen in other models of cervical SCI.

Conclusions: We developed a novel model of SCI which was non-surgical, well-tolerated, localized, and replicated the pathology seen in other models of SCI.
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http://dx.doi.org/10.1016/j.jneumeth.2014.06.018DOI Listing
September 2014

Preclinical pharmacokinetic and toxicological evaluation of MIF-1 peptidomimetic, PAOPA: examining the pharmacology of a selective dopamine D2 receptor allosteric modulator for the treatment of schizophrenia.

Peptides 2013 Apr 15;42:89-96. Epub 2013 Feb 15.

Department of Psychiatry and Behavioral Neurosciences, McMaster University, Hamilton, Ontario, Canada.

Schizophrenia is a mental illness characterized by a breakdown in cognition and emotion. Over the years, drug treatment for this disorder has mainly been compromised of orthosteric ligands that antagonize the active site of the dopamine D2 receptor. However, these drugs are limited in their use and often lead to the development of adverse movement and metabolic side effects. Allosteric modulators are an emerging class of therapeutics with significant advantages over orthosteric ligands, including an improved therapeutic and safety profile. This study investigates our newly developed allosteric modulator, PAOPA, which is a specific modulator of the dopamine D2 receptor. Previous studies have shown PAOPA to attenuate schizophrenia-like behavioral abnormalities in preclinical models. To advance this newly developed allosteric drug from the preclinical to clinical stage, this study examines the pharmacokinetic behavior and toxicological profile of PAOPA. Results from this study prove the effectiveness of PAOPA in reaching the implicated regions of the brain for therapeutic action, particularly the striatum. Pharmacokinetic parameters of PAOPA were found to be comparable to current market antipsychotic drugs. Necropsy and histopathological analyses showed no abnormalities in all examined organs. Acute and chronic treatment of PAOPA indicated no movement abnormalities commonly found with the use of current typical antipsychotic drugs. Moreover, acute and chronic PAOPA treatment revealed no hematological or metabolic abnormalities classically found with the use of atypical antipsychotic drugs. Findings from this study demonstrate a better safety profile of PAOPA, and necessitates the progression of this newly developed therapeutic for the treatment of schizophrenia.
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http://dx.doi.org/10.1016/j.peptides.2013.02.004DOI Listing
April 2013
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