Publications by authors named "Jayakumar Rajadas"

126 Publications

Adipose-derived stromal cells seeded in pullulan-collagen hydrogels improve healing in murine burns.

Tissue Eng Part A 2021 Apr 1. Epub 2021 Apr 1.

Stanford University School of Medicine, Surgery, GK-201, 257 Campus Drive West, Stanford, California, United States, 94305;

Burn scars and scar contractures cause significant morbidity for patients. Recently, cell-based therapies have been proposed as an option for improving healing and reducing scarring after burn injury, through their known pro-angiogenic and immunomodulatory paracrine effects. Our lab has developed a pullulan-collagen hydrogel that, when seeded with mesenchymal stem cells (MSCs), improves cell viability and augments their pro-angiogenic capacity in vivo. Concurrently, recent research suggests that prospective isolation of cell subpopulations with desirable transcriptional profiles can be used to further improve cell-based therapies. In this study, we examined whether adipose-derived stem cell-seeded hydrogels could improve wound healing following thermal injury using a murine contact burn model. Partial thickness contact burns were created on the dorsum of mice. On days 5 and 10 following injury, burns were debrided and received either ASC-hydrogel, ASC injection alone, hydrogel alone, or no treatment. On days 10 and 25, burns were harvested for histologic and molecular analysis. This experiment was repeated using CD26+/CD55+ FACS-enriched ASCs to further evaluate the regenerative potential of ASCs in wound healing. ASC-hydrogel-treated burns demonstrated accelerated time to re-epithelialization, greater vascularity, and increased expression of the pro-angiogenic genes MCP-1, VEGF, and SDF-1 at both the mRNA and protein level. Expression of the pro-fibrotic gene Timp1 and pro-inflammatory gene Tnfa were down-regulated in ASC-hydrogel treated burns. ASC-hydrogel treated burns exhibited reduced scar area compared to hydrogel-treated and control wounds, with equivalent scar density. CD26+/CD55+ ASC-hydrogel treatment resulted in accelerated healing, increased dermal appendage count, and improved scar quality with a more reticular collagen pattern. Here we find that ASC-hydrogel therapy is effective for treating burns, with demonstrated pro-angiogenic, fibro-modulatory and immunomodulatory effects. Enrichment for CD26+/CD55+ ASCs has additive benefits for tissue architecture and collagen remodeling post-burn injury. Research is ongoing to further facilitate clinical translation of this promising therapeutic approach.
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http://dx.doi.org/10.1089/ten.TEA.2020.0320DOI Listing
April 2021

Integrated Ca flux and AFM force analysis in human iPSC-derived cardiomyocytes.

Biol Chem 2020 11 27;402(1):113-121. Epub 2020 Oct 27.

Heart Center, Department of Cardiology and Pneumology, University Medical Center, Göttingen University, Robert-Koch-Strasse 40, D-37075, Göttingen, Germany.

We developed a new approach for combined analysis of calcium (Ca) handling and beating forces in contractile cardiomyocytes. We employed human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) from dilated cardiomyopathy (DCM) patients carrying an inherited mutation in the sarcomeric protein troponin T (TnT), and isogenic TnT-KO iPSC-CMs generated via CRISPR/Cas9 gene editing. In these cells, Ca handling as well as beating forces and -rates using single-cell atomic force microscopy (AFM) were assessed. We report impaired Ca handling and reduced contractile force in DCM iPSC-CMs compared to healthy WT controls. TnT-KO iPSC-CMs display no contractile force or Ca transients but generate Ca sparks. We apply our analysis strategy to Ca traces and AFM deflection recordings to reveal maximum rising rate, decay time, and duration of contraction with a multi-step background correction. Our method provides adaptive computing of signal peaks for different Ca flux or force levels in iPSC-CMs, as well as analysis of Ca sparks. Moreover, we report long-term measurements of contractile force dynamics on human iPSC-CMs. This approach enables deeper and more accurate profiling of disease-specific differences in cardiomyocyte contraction profiles using patient-derived iPSC-CMs.
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http://dx.doi.org/10.1515/hsz-2020-0212DOI Listing
November 2020

Dendritic Cells as Targets for Biomaterial-Based Immunomodulation.

ACS Biomater Sci Eng 2020 05 28;6(5):2726-2739. Epub 2020 Apr 28.

Biomaterials and Advanced Drug Delivery Laboratory, Stanford University School of Medicine, Stanford, California 94305, United States.

Various subtypes of immunocytes react against implanted biomaterials to eliminate the foreign body object from the host's body. Among these cells, dendritic cells (DCs) play a key role in early immune response, later engaging lymphocytes through antigens presentation. Due to their capability to induce tolerogenic or immunogenic responses, DCs have been considered as key therapeutic targets for immunomodulatory products. For instance, tolerogenic DCs are applied in the treatment of autoimmune diseases, rejection of allograft transplantation, and implanted biomaterial. Due to the emerging importance of DCs in immunomodulatory biomaterials, this Review summarizes DCs' responses-such as adhesion, migration, and maturation-to biomaterials. We also review some examples of key molecules and their applications in DCs' immunoengineering. These evaluations would pave the way for designing advanced biomaterials and nanomaterials to modulate the immune system, applicable in tissue engineering, transplantation, and drug delivery technologies.
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http://dx.doi.org/10.1021/acsbiomaterials.9b01987DOI Listing
May 2020

Association of serum allopregnanolone with restricted and repetitive behaviors in adult males with autism.

Psychoneuroendocrinology 2021 Jan 4;123:105039. Epub 2020 Nov 4.

Department of Psychiatry & Behavioral Sciences, Stanford University, California, USA. Electronic address:

Autism spectrum disorder (ASD) has been associated with imbalance between excitatory and inhibitory (E/I) neurotransmission systems, as well as with neuroinflammation. Sitting at the crossroads between E/I imbalance and neuroinflammation is a class of endogenous hormones known as neurosteroids. Current literature points to dysregulated steroid metabolism and atypical neurosteroid levels in ASD as early as in utero. However, due to the complexity of neurosteroid metabolomics, including possible sex differences, the impact of neurosteroids on ASD symptomatology remains unclear. In this study, we assessed neurosteroid levels and ASD symptom severity of 21 males with ASD and 20 full-scale-IQ-matched typically developing (TD) males, all aged 18-39. Using liquid chromatography-tandem mass spectrometry, concentrations of allopregnanolone, cortisol, dehydroepiandrosterone, progesterone, and testosterone were measured in saliva and serum. With the exception of cortisol's, all neurosteroids' concentrations were found to have ASD vs. TD group differences in distribution, where one group was normally distributed and the other non-normally distributed. Serum allopregnanolone levels in males with ASD were found to negatively correlate with clinician-rated measures of restricted and repetitive behavior measures (ADOS-2 RRB and ADI-R RRSB domain scores). Additionally, lower serum allopregnanolone levels were found to predict more negative camouflaging scores, which represent greater differences in self- and clinician-rated symptom severity, of both ASD symptomatology overall and repetitive behaviors in particular. Taken together, our findings demonstrate that in adult males with ASD, decreased serum allopregnanolone levels are associated with more severe restricted and repetitive behaviors and with less insight into the severity of these behaviors.
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http://dx.doi.org/10.1016/j.psyneuen.2020.105039DOI Listing
January 2021

The Effect of Ethanol Consumption on Composition and Morphology of Femur Cortical Bone in Wild-Type and ALDH2*2-Homozygous Mice.

Calcif Tissue Int 2021 Feb 17;108(2):265-276. Epub 2020 Oct 17.

Biomaterials and Advanced Drug Delivery Laboratory, Stanford Medical School, Stanford, CA, 94305, USA.

ALDH2 inactivating mutation (ALDH2*2) is the most abundant mutation leading to bone morphological aberration. Osteoporosis has long been associated with changes in bone biomaterial in elderly populations. Such changes can be exacerbated with elevated ethanol consumption and in subjects with impaired ethanol metabolism, such as carriers of aldehyde dehydrogenase 2 (ALDH2)-deficient gene, ALDH2*2. So far, little is known about bone compositional changes besides a decrease in mineralization. Raman spectroscopic imaging has been utilized to study the changes in overall composition of C57BL/6 female femur bone sections, as well as in compound spatial distribution. Raman maps of bone sections were analyzed using multilinear regression with these four isolated components, resulting in maps of their relative distribution. A 15-week treatment of both wild-type (WT) and ALDH2*2/*2 mice with 20% ethanol in the drinking water resulted in a significantly lower mineral content (p < 0.05) in the bones. There was no significant change in mineral and collagen content due to the mutation alone (p > 0.4). Highly localized islets of elongated adipose tissue were observed on most maps. Elevated fat content was found in ALDH2*2 knock-in mice consuming ethanol (p < 0.0001) and this effect appeared cumulative. This work conclusively demonstrates that that osteocytes in femurs of older female mice accumulate fat, as has been previously theorized, and that fat accumulation is likely modulated by levels of acetaldehyde, the ethanol metabolite.
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http://dx.doi.org/10.1007/s00223-020-00769-1DOI Listing
February 2021

Repurposing Disulfiram (Tetraethylthiuram Disulfide) as a Potential Drug Candidate against In Vitro and In Vivo.

Antibiotics (Basel) 2020 Sep 22;9(9). Epub 2020 Sep 22.

Biomaterials and Advanced Drug Delivery, Stanford Cardiovascular Pharmacology Division, Cardiovascular Institute, Stanford University School of Medicine, Palo Alto, CA 94304, USA.

Lyme disease caused by the () is the most common vector-borne, multi-systemic disease in the USA. Although most Lyme disease patients can be cured with a course of the first line of antibiotic treatment, some patients are intolerant to currently available antibiotics, necessitating the development of more effective therapeutics. We previously found several drugs, including disulfiram, that exhibited effective activity against . In the current study, we evaluated the potential of repurposing the FDA-approved drug, disulfiram for its borreliacidal activity. Our results indicate disulfiram has excellent borreliacidal activity against both the log and stationary phase . Treatment of mice with disulfiram eliminated the completely from the hearts and urinary bladder by day 28 post infection. Moreover, disulfiram-treated mice showed reduced expressions of inflammatory markers, and thus they were protected from histopathology and cardiac organ damage. Furthermore, disulfiram-treated mice showed significantly lower amounts of total antibody titers (IgM and IgG) at day 21 and total IgG2b at day 28 post infection. FACS analysis of lymph nodes revealed a decrease in the percentage of CD19+ B cells and an increase in total percentage of CD3+ T cells, CD3+ CD4+ T helpers, and naive and effector memory cells in disulfiram-treated mice. Together, our findings suggest that disulfiram has the potential to be repurposed as an effective antibiotic for treating Lyme disease.
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http://dx.doi.org/10.3390/antibiotics9090633DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7557442PMC
September 2020

Upregulation of CD47 Is a Host Checkpoint Response to Pathogen Recognition.

mBio 2020 06 23;11(3). Epub 2020 Jun 23.

Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA

It is well understood that the adaptive immune response to infectious agents includes a modulating suppressive component as well as an activating component. We now show that the very early innate response also has an immunosuppressive component. Infected cells upregulate the CD47 "don't eat me" signal, which slows the phagocytic uptake of dying and viable cells as well as downstream antigen-presenting cell (APC) functions. A CD47 mimic that acts as an essential virulence factor is encoded by all poxviruses, but CD47 expression on infected cells was found to be upregulated even by pathogens, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), that encode no mimic. CD47 upregulation was revealed to be a host response induced by the stimulation of both endosomal and cytosolic pathogen recognition receptors (PRRs). Furthermore, proinflammatory cytokines, including those found in the plasma of hepatitis C patients, upregulated CD47 on uninfected dendritic cells, thereby linking innate modulation with downstream adaptive immune responses. Indeed, results from antibody-mediated CD47 blockade experiments as well as CD47 knockout mice revealed an immunosuppressive role for CD47 during infections with lymphocytic choriomeningitis virus and Since CD47 blockade operates at the level of pattern recognition receptors rather than at a pathogen or antigen-specific level, these findings identify CD47 as a novel potential immunotherapeutic target for the enhancement of immune responses to a broad range of infectious agents. Immune responses to infectious agents are initiated when a pathogen or its components bind to pattern recognition receptors (PRRs). PRR binding sets off a cascade of events that activates immune responses. We now show that, in addition to activating immune responses, PRR signaling also initiates an immunosuppressive response, probably to limit inflammation. The importance of the current findings is that blockade of immunomodulatory signaling, which is mediated by the upregulation of the CD47 molecule, can lead to enhanced immune responses to any pathogen that triggers PRR signaling. Since most or all pathogens trigger PRRs, CD47 blockade could be used to speed up and strengthen both innate and adaptive immune responses when medically indicated. Such immunotherapy could be done without a requirement for knowing the HLA type of the individual, the specific antigens of the pathogen, or, in the case of bacterial infections, the antimicrobial resistance profile.
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http://dx.doi.org/10.1128/mBio.01293-20DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7315125PMC
June 2020

Azlocillin can be the potential drug candidate against drug-tolerant Borrelia burgdorferi sensu stricto JLB31.

Sci Rep 2020 03 2;10(1):3798. Epub 2020 Mar 2.

Biomaterials and Advanced Drug Delivery, Stanford Cardiovascular Pharmacology Division, Cardiovascular Institute, Stanford University School of Medicine, Palo Alto, California, 94304, USA.

Lyme disease is one of most common vector-borne diseases, reporting more than 300,000 cases annually in the United States. Treating Lyme disease during its initial stages with traditional tetracycline antibiotics is effective. However, 10-20% of patients treated with antibiotic therapy still shows prolonged symptoms of fatigue, musculoskeletal pain, and perceived cognitive impairment. When these symptoms persists for more than 6 months to years after completing conventional antibiotics treatment are called post-treatment Lyme disease syndrome (PTLDS). Though the exact reason for the prolongation of post treatment symptoms are not known, the growing evidence from recent studies suggests it might be due to the existence of drug-tolerant persisters. In order to identify effective drug molecules that kill drug-tolerant borrelia we have tested two antibiotics, azlocillin and cefotaxime that were identified by us earlier. The in vitro efficacy studies of azlocillin and cefotaxime on drug-tolerant persisters were done by semisolid plating method. The results obtained were compared with one of the currently prescribed antibiotic doxycycline. We found that azlocillin completely kills late log phase and 7-10 days old stationary phase B. burgdorferi. Our results also demonstrate that azlocillin and cefotaxime can effectively kill in vitro doxycycline-tolerant B. burgdorferi. Moreover, the combination drug treatment of azlocillin and cefotaxime effectively killed doxycycline-tolerant B. burgdorferi. Furthermore, when tested in vivo, azlocillin has shown good efficacy against B. burgdorferi in mice model. These seminal findings strongly suggests that azlocillin can be effective in treating B. burgdorferi sensu stricto JLB31 infection and furthermore in depth research is necessary to evaluate its potential use for Lyme disease therapy.
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http://dx.doi.org/10.1038/s41598-020-59600-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7052277PMC
March 2020

Amyloid protein aggregates: new clients for mitochondrial energy production in the brain?

FEBS J 2020 Aug 13;287(16):3386-3395. Epub 2020 Feb 13.

Biomaterials and Advanced Drug Delivery Laboratory, Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, USA.

Mitochondria are key organelles, which maintain energy metabolism and cellular homeostasis. Mitochondria support transcriptional regulation and proteostatic signaling mechanisms through crosstalk between the mitochondria itself, the nucleus, and the cytoplasm. Mitochondrial dysfunction leads to impaired proteostasis, and both are key pathological features of age-related neurological disorders. For example, Alzheimer's and Parkinson's diseases feature mitochondrial-targeted protein aggregates and impaired mitochondrial function, although the mechanistic causes are poorly understood. Vascular abnormalities and hypometabolism in such neurological diseases are reported several years before key clinical disease symptoms even become apparent. Recent investigations suggest that processing of such aggregates within mitochondria can offer protective functions, specifically by restoring energy (ATP) in starving cells. We hypothesize that the accumulation of protein aggregates in mitochondria can not only disrupt its functions, but also render a protective role to fulfill energy demands in hypometabolic conditions. Growing evidence favors mitochondrial defense to toxic amyloid aggregates/oligomers as a protective response. In this viewpoint article, we will present several publications (in addition to our own) that serve to connect the possible role of protein aggregates in mitochondrial energy production for degenerative conditions.
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http://dx.doi.org/10.1111/febs.15225DOI Listing
August 2020

Pharmacological antagonism of histamine H2R ameliorated L-DOPA-induced dyskinesia via normalization of GRK3 and by suppressing FosB and ERK in PD.

Neurobiol Aging 2019 09 19;81:177-189. Epub 2019 Jun 19.

Biomaterials and Advanced Drug Delivery Laboratory, School of Medicine, Stanford University, Palo Alto, CA, USA; Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco. Electronic address:

Parkinson's disease (PD) is often managed with L-3,4-dihydroxyphenylalanine (L-DOPA), which is still the gold standard to relieve the clinical motor symptoms of PD. However, chronic use of L-DOPA leads to significant motor complications, especially L-DOPA-induced dyskinesia (LID), which limit the therapeutic benefit. Few options are available for the pharmacological management of LID partly due to the inadequacy of our mechanistic understanding of the syndrome. We focused on the role of the histamine (HA) H2 receptor (H2R) in the striatum, which others have shown to be involved in the development of LID. We generated LID in a hemiparkinsonian mouse model and tested the signaling effects of ranitidine, an H2R antagonist. We used histidine decarboxylase deficient mice (Hdc-Ko) which lacks HA to study the role of G-protein-coupled receptor kinases (GRKs) in HA deficiency. Loss of HA in Hdc-Ko mice did not result in the downregulation of GRKs, especially GRK3 and GRK6, which were previously found to be reduced in hemiparkinsonian animal models. Ranitidine, when given along with L-DOPA, normalized the expression of GRK3 in the dopamine-depleted striatum thereby inhibiting LID in mice. The extracellular signal regulated kinase and ΔFosB signaling pathways were attenuated in the lesioned striatum when ranitidine was combined with L-DOPA than L-DOPA alone. These results demonstrate that ranitidine inhibits LID by normalizing the levels of GRK3, extracellular signal regulated kinase activation, and FosB accumulation in the dopamine-depleted striatum via HA H2R antagonism.
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http://dx.doi.org/10.1016/j.neurobiolaging.2019.06.004DOI Listing
September 2019

Optimization of transdermal deferoxamine leads to enhanced efficacy in healing skin wounds.

J Control Release 2019 08 9;308:232-239. Epub 2019 Jul 9.

Hagey Laboratory for Pediatric Regenerative Medicine, Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA. Electronic address:

Chronic wounds remain a significant burden to both the healthcare system and individual patients, indicating an urgent need for new interventions. Deferoxamine (DFO), an iron-chelating agent clinically used to treat iron toxicity, has been shown to reduce oxidative stress and increase hypoxia-inducible factor-1 alpha (HIF-1α) activation, thereby promoting neovascularization and enhancing regeneration in chronic wounds. However due to its short half-life and adverse side effects associated with systemic absorption, there is a pressing need for targeted DFO delivery. We recently published a preclinical proof of concept drug delivery system (TDDS) which showed that transdermally applied DFO is effective in improving chronic wound healing. Here we present an enhanced TDDS (eTDDS) comprised exclusively of FDA-compliant constituents to optimize drug release and expedite clinical translation. We evaluate the eTDDS to the original TDDS and compare this with other commonly used delivery methods including DFO drip-on and polymer spray applications. The eTDDS displayed excellent physicochemical characteristics and markedly improved DFO delivery into human skin when compared to other topical application techniques. We demonstrate an accelerated wound healing response with the eTDDS treatment resulting in significantly increased wound vascularity, dermal thickness, collagen deposition and tensile strength. Together, these findings highlight the immediate clinical potential of DFO eTDDS to treating diabetic wounds. Further, the topical drug delivery platform has important implications for targeted pharmacologic therapy of a wide range of cutaneous diseases.
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http://dx.doi.org/10.1016/j.jconrel.2019.07.009DOI Listing
August 2019

Salivary Thiocyanate as a Biomarker of Cystic Fibrosis Transmembrane Regulator Function.

Anal Chem 2019 06 4;91(12):7929-7934. Epub 2019 Jun 4.

Center for Excellence in Pulmonary Biology, Department of Pediatrics , Stanford University , Stanford , California 94304 , United States.

Improved methods are needed to reliably assess Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) function in vivo in light of recent therapeutic developments targeting the CFTR protein. Oral fluid from patients with cystic fibrosis (CF) and healthy controls (HCs) were studied using colorimetry and nonresonant Raman spectroscopy. Colorimetry experiments showed only a 36% decrease in thiocyanate (SCN) concentration, but a sharp Raman peak at 2068 cm, attributable to (SCN) vibrations, normalized to C-H peak, was on average 18 times higher for HC samples. Samples from patients undergoing treatment with CFTR modulators including ivacaftor, lumacaftor, and tezacaftor showed a high normalized peak in response to therapy. The peak intensity was consistent in longitudinal samples from single donors and in stored samples. The Raman peak ratio is a more sensitive, convenient, noninvasive biomarker for assessments of the therapeutic efficacy of drugs targeting CFTR and provides a value that is in much better agreement with theoretical expectations of saliva SCN concentrations compared to colorimetry. This insight may greatly facilitate assessments of CFTR modulator efficacy in individual patients.
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http://dx.doi.org/10.1021/acs.analchem.9b01800DOI Listing
June 2019

Adenosine and hyaluronan promote lung fibrosis and pulmonary hypertension in combined pulmonary fibrosis and emphysema.

Dis Model Mech 2019 05 15;12(5). Epub 2019 May 15.

Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA

Combined pulmonary fibrosis and emphysema (CPFE) is a syndrome that predominantly affects male smokers or ex-smokers and it has a mortality rate of 55% and a median survival of 5 years. Pulmonary hypertension (PH) is a frequently fatal complication of CPFE. Despite this dismal prognosis, no curative therapies exist for patients with CPFE outside of lung transplantation and no therapies are recommended to treat PH. This highlights the need to develop novel treatment approaches for CPFE. Studies from our group have demonstrated that both adenosine and its receptor ADORA2B are elevated in chronic lung diseases. Activation of ADORA2B leads to elevated levels of hyaluronan synthases (HAS) and increased hyaluronan, a glycosaminoglycan that contributes to chronic lung injury. We hypothesize that ADORA2B and hyaluronan contribute to CPFE. Using isolated CPFE lung tissue, we characterized expression levels of ADORA2B and HAS. Next, using a unique mouse model of experimental lung injury that replicates features of CPFE, namely airspace enlargement, PH and fibrotic deposition, we investigated whether 4MU, a HAS inhibitor, was able to inhibit features of CPFE. Increased protein levels of ADORA2B and HAS3 were detected in CPFE and in our experimental model of CPFE. Treatment with 4MU was able to attenuate PH and fibrosis but not airspace enlargement. This was accompanied by a reduction of HAS3-positive macrophages. We have generated pre-clinical data demonstrating the capacity of 4MU, an FDA-approved drug, to attenuate features of CPFE in an experimental model of chronic lung injury.This article has an associated First Person interview with the first author of the paper.
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http://dx.doi.org/10.1242/dmm.038711DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6550050PMC
May 2019

4-Methylumbelliferyl glucuronide contributes to hyaluronan synthesis inhibition.

J Biol Chem 2019 05 26;294(19):7864-7877. Epub 2019 Mar 26.

From the Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, California 94305.

4-Methylumbelliferone (4-MU) inhibits hyaluronan (HA) synthesis and is an approved drug used for managing biliary spasm. However, rapid and efficient glucuronidation is thought to limit its utility for systemically inhibiting HA synthesis. In particular, 4-MU in mice has a short half-life, causing most of the drug to be present as the metabolite 4-methylumbelliferyl glucuronide (4-MUG), which makes it remarkable that 4-MU is effective at all. We report here that 4-MUG contributes to HA synthesis inhibition. We observed that oral administration of 4-MUG to mice inhibits HA synthesis, promotes FoxP3 regulatory T-cell expansion, and prevents autoimmune diabetes. Mice fed either 4-MUG or 4-MU had equivalent 4-MU:4-MUG ratios in serum, liver, and pancreas, indicating that 4-MU and 4-MUG reach an equilibrium in these tissues. LC-tandem MS experiments revealed that 4-MUG is hydrolyzed to 4-MU in serum, thereby greatly increasing the effective bioavailability of 4-MU. Moreover, using intravital 2-photon microscopy, we found that 4-MUG (a nonfluorescent molecule) undergoes conversion into 4-MU (a fluorescent molecule) and that 4-MU is extensively tissue bound in the liver, fat, muscle, and pancreas of treated mice. 4-MUG also suppressed HA synthesis independently of its conversion into 4-MU and without depletion of the HA precursor UDP-glucuronic acid (GlcUA). Together, these results indicate that 4-MUG both directly and indirectly inhibits HA synthesis and that the effective bioavailability of 4-MU is higher than previously thought. These findings greatly alter the experimental and therapeutic possibilities for HA synthesis inhibition.
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http://dx.doi.org/10.1074/jbc.RA118.006166DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6514619PMC
May 2019

Fidgetin-Like 2 siRNA Enhances the Wound Healing Capability of a Surfactant Polymer Dressing.

Adv Wound Care (New Rochelle) 2019 Mar 5;8(3):91-100. Epub 2019 Mar 5.

MicroCures, Inc., Research and Development, Bronx, New York.

Microtubules (MTs) are intracellular polymers that provide structure to the cell, serve as railways for intracellular transport, and regulate many cellular activities, including cell migration. The dynamicity and function of the MT cytoskeleton are determined in large part by its regulatory proteins, including the recently discovered MT severing enzyme Fidgetin-like 2 (FL2). Downregulation of FL2 expression with small interfering RNA (siRNA) results in a more than twofold increase in cell migration rate as well as translates into improved wound-healing outcomes in mouse models. Here we utilized a commercially available surfactant polymer dressing (SPD) as a vehicle to deliver FL2 siRNA. To this end we incorporated collagen microparticles containing FL2 siRNA into SPD (SPD-FL2-siRNA) for direct application to the injury site. Topical application of SPD-FL2 siRNA to murine models of full-thickness excision wounds and full-thickness burn wounds resulted in significant improvements in the rate and quality of wound healing, as measured clinically and histologically, compared with controls. Wound healing occurred more rapidly and with high fidelity, resulting in properly organized collagen substructure. Taken together, these findings indicate that the incorporation of FL2 siRNA into existing treatment options is a promising avenue to improve wound outcomes.
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http://dx.doi.org/10.1089/wound.2018.0827DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6430983PMC
March 2019

Conformational Preferences of Aβ25-35 and Aβ35-25 in Membrane Mimicking Environments.

Protein Pept Lett 2019 ;26(5):386-390

Bioorganic Chemistry Laboratory, Central Leather Research Institute, Adyar, Chennai 600 020, India.

Background: The structural transition of aggregating Abeta peptides is the key event in the progression of Alzheimer's Disease (AD).

Objective: In the present work, the structural modifications of toxic Aβ25-35 and the scrambled Aβ35-25 were studied in Trifluoroethanol (TFE) and in aqueous SDS micelles.

Methods: Using CD spectroscopic investigations, the conformational transition of Aβ25-35 and Aβ35-25 peptides were determined in different membrane mimicking environments such as TFE and SDS. An interval scan CD of the peptides on evaporation of TFE was performed. TFE titrations were carried out to investigate the intrinsic ability of the structural conformations of peptides.

Results: We show by spectroscopic evidence that Aβ25-35 prefers beta sheet structures upon increasing TFE concentrations. On the other hand, the non-toxic scrambled Aβ35-25 peptide only undergoes a transition from random coil to α-helix conformation with increasing TFE. In the interval scan studies, Aβ25-35 did not show any structural transitions, whereas Aβ35-25 showed transition from α-helix to β-sheet conformation. In membrane simulating aqueous SDS micelles, Aβ25-35 showed a transition from random coil to α-helix while Aβ35-25 underwent transition from random coil to β-sheet conformation.

Conclusion: Overall, the current results seek new insights into the structural properties of amyloidogenic and the truncated sequence in membrane mimicking solvents.
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http://dx.doi.org/10.2174/0929866526666190228122849DOI Listing
October 2019

Possible Clues for Brain Energy Translation via Endolysosomal Trafficking of APP-CTFs in Alzheimer's Disease.

Oxid Med Cell Longev 2018 21;2018:2764831. Epub 2018 Oct 21.

Biomaterials and Advanced Drug Delivery Laboratory, Stanford University School of Medicine, Stanford, CA 94305, USA.

Vascular dysfunctions, hypometabolism, and insulin resistance are high and early risk factors for Alzheimer's disease (AD), a leading neurological disease associated with memory decline and cognitive dysfunctions. Early defects in glucose transporters and glycolysis occur during the course of AD progression. Hypometabolism begins well before the onset of early AD symptoms; this timing implicates the vulnerability of hypometabolic brain regions to beta-secretase 1 (BACE-1) upregulation, oxidative stress, inflammation, synaptic failure, and cell death. Despite the fact that ketone bodies, astrocyte-neuron lactate shuttle, pentose phosphate pathway (PPP), and glycogenolysis compensate to provide energy to the starving AD brain, a considerable energy crisis still persists and increases during disease progression. Studies that track brain energy metabolism in humans, animal models of AD, and studies reveal striking upregulation of beta-amyloid precursor protein (-APP) and carboxy-terminal fragments (CTFs). Currently, the precise role of CTFs is unclear, but evidence supports increased endosomal-lysosomal trafficking of -APP and CTFs through autophagy through a vague mechanism. While intracellular accumulation of A is attributed as both the cause and consequence of a defective endolysosomal-autophagic system, much remains to be explored about the other -APP cleavage products. Many recent works report altered amino acid catabolism and expression of several urea cycle enzymes in AD brains, but the precise cause for this dysregulation is not fully explained. In this paper, we try to connect the role of CTFs in the energy translation process in AD brain based on recent findings.
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http://dx.doi.org/10.1155/2018/2764831DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6215552PMC
December 2018

Characterization of Brain Dysfunction Induced by Bacterial Lipopeptides That Alter Neuronal Activity and Network in Rodent Brains.

J Neurosci 2018 12 31;38(50):10672-10691. Epub 2018 Oct 31.

Biomaterials and Advanced Drug Delivery Laboratory, Stanford University School of Medicine, Palo Alto, California 94304,

The immunopathological states of the brain induced by bacterial lipoproteins have been well characterized by using biochemical and histological assays. However, these studies have limitations in determining functional states of damaged brains involving aberrant synaptic activity and network, which makes it difficult to diagnose brain disorders during bacterial infection. To address this, we investigated the effect of PamCSK (PAM), a synthetic bacterial lipopeptide, on synaptic dysfunction of female mice brains and cultured neurons in parallel. Our functional brain imaging using PET with [F]fluorodeoxyglucose and [F] flumazenil revealed that the brain dysfunction induced by PAM is closely aligned to disruption of neurotransmitter-related neuronal activity and functional correlation in the region of the limbic system rather than to decrease of metabolic activity of neurons in the injection area. This finding was verified by tissue experiments that analyzed synaptic and dendritic alterations in the regions where PET imaging showed abnormal neuronal activity and network. Recording of synaptic activity also revealed that PAM reorganized synaptic distribution and decreased synaptic plasticity in hippocampus. Further study using neuron cultures demonstrated that PAM decreased the number of presynapses and the frequency of miniature EPSCs, which suggests PAM disrupts neuronal function by damaging presynapses exclusively. We also showed that PAM caused aggregation of synapses around dendrites, which may have caused no significant change in expression level of synaptic proteins, whereas synaptic number and function were impaired by PAM. Our findings could provide a useful guide for diagnosis and treatment of brain disorders specific to bacterial infection. It is challenging to diagnose brain disorders caused by bacterial infection because neural damage induced by bacterial products involves nonspecific neurological symptoms, which is rarely detected by laboratory tests with low spatiotemporal resolution. To better understand brain pathology, it is essential to detect functional abnormalities of brain over time. To this end, we investigated characteristic patterns of altered neuronal integrity and functional correlation between various regions in mice brains injected with bacterial lipopeptides using PET with a goal to apply new findings to diagnosis of brain disorder specific to bacterial infection. In addition, we analyzed altered synaptic density and function using both and experimental models to understand how bacterial lipopeptides impair brain function and network.
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http://dx.doi.org/10.1523/JNEUROSCI.0825-17.2018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6580656PMC
December 2018

Anti-hyperlipidaemic effects of synthetic analogues of nordihydroguaiaretic acid in dyslipidaemic rats.

Br J Pharmacol 2019 02 10;176(3):369-385. Epub 2018 Dec 10.

Geriatric Research, Education and Clinical Center, VA Palo Alto Health Care System, Palo Alto, CA, USA.

Background And Purpose: Previous studies have shown that Creosote bush-derived nordihydroguaiaretic acid (NDGA) exerts beneficial actions on the key components of metabolic syndrome including dyslipidaemia, insulin resistance and hypertension in several relevant rodent models. Here, we synthesized and screened a total of 6 anti-hyperlipidaemic analogues of NDGA and tested their efficacy against hepatic lipid metabolism in a high-fructose diet (HFrD) fed dyslipidaemic rat model.

Experimental Approach: HFrD fed Sprague-Dawley rats treated with NDGA or one of the six analogues were used. Serum samples were analysed for blood metabolites, whereas liver samples were quantified for changes in various mRNA levels by real-time RT-PCR.

Key Results: Oral gavage of HFrD-fed rats for 4 days with NDGA analogues 1 and 2 (100 mg·kg ·day ) suppressed the hepatic triglyceride content, whereas the NDGA analogues 2, 3 and 4, like NDGA, decreased the plasma triglyceride levels by 70-75%. qRT-PCR measurements demonstrated that among NDGA analogues 1, 2, 4 and 5, analogue 4 was the most effective at inhibiting the mRNA levels of some key enzymes and transcription factors involved in lipogenesis. All four analogues almost equally inhibited the key genes involved in triglyceride synthesis and fatty acid elongation. Unlike NDGA, none of the analogues affected the genes of hepatic fatty acid oxidation or transport.

Conclusions And Implications: Our data suggest that NDGA analogues 1, 2, 4 and 5, particularly analogue 4, exert their anti-hyperlipidaemic actions by negatively targeting genes of key enzymes and transcription factors involved in lipogenesis, triglyceride synthesis and fatty acid elongation. These analogues have therapeutic potential.
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http://dx.doi.org/10.1111/bph.14528DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6329620PMC
February 2019

In vitro and in vivo evaluation of cephalosporins for the treatment of Lyme disease.

Drug Des Devel Ther 2018 11;12:2915-2921. Epub 2018 Sep 11.

Biomaterials and Advanced Drug Delivery, Stanford Cardiovascular Pharmacology Division, Cardiovascular Institute, School of Medicine, Stanford University, Palo Alto, CA, USA,

Background: Lyme disease accounts for >90% of all vector-borne disease cases in the United States and affect ~300,000 persons annually in North America. Though traditional tetracycline antibiotic therapy is generally prescribed for Lyme disease, still 10%-20% of patients treated with current antibiotic therapy still show lingering symptoms.

Methods: In order to identify new drugs, we have evaluated four cephalosporins as a therapeutic alternative to commonly used antibiotics for the treatment of Lyme disease by using microdilution techniques like minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). We have determined the MIC and MBC of four drugs for three Borrelia burgdorferi s.s strains namely CA8, JLB31 and NP40. The binding studies were performed using in silico analysis.

Results: The MIC order of the four drugs tested is cefoxitin (1.25 µM/mL) > cefamandole (2.5 µM/mL), > cefuroxime (5 µM/mL) > cefapirin (10 µM/mL). Among the drugs that are tested in this study using in vivo C3H/HeN mouse model, cefoxitin effectively kills B. burgdorferi. The in silico analysis revealed that all four cephalosporins studied binds effectively to B. burgdorferi proteins, SecA subunit penicillin-binding protein (PBP) and Outer surface protein E (OspE).

Conclusion: Based on the data obtained, cefoxitin has shown high efficacy killing B. burgdorferi at concentration of 1.25 µM/mL. In addition to it, cefoxitin cleared B. burgdorferi infection in C3H/HeN mice model at 20 mg/kg.
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http://dx.doi.org/10.2147/DDDT.S164966DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6141111PMC
February 2019

Cytokines as therapeutic agents and targets in heart disease.

Cytokine Growth Factor Rev 2018 10 16;43:54-68. Epub 2018 Aug 16.

Biomaterials and Advanced Drug Delivery Laboratory, Stanford University School of Medicine, Palo Alto, CA 94304, USA. Electronic address:

Cytokine therapies have emerged during the past decade as promising noninvasive treatments for heart disease. In general, current drug treatments are directed towards symptom control and prevention of disease progression; however, many agents also produce cause side effects that alter quality of life. Cytokine based therapies have the potential to reduce post-infarct heart failure and chronic ischemia by stimulating the proliferation and differentiation of endothelial cells and bone marrow hematopoietic stem cells and mobilizing these cells toward ischemic tissue. In turn, these mobilized cell populations contribute to myocardial regeneration. In contrast, over-expression of several cytokines has been linked to a variety of heart diseases; thus, therapies targeting and monitoring these cytokines are of great interest. Here we summarize results from clinical studies on cytokines as therapeutic agents or therapeutic targets in the treatment for heart disease as well as cytokines involved in the evolution of heart disease.
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http://dx.doi.org/10.1016/j.cytogfr.2018.08.003DOI Listing
October 2018

Deferoxamine can prevent pressure ulcers and accelerate healing in aged mice.

Wound Repair Regen 2018 05 25;26(3):300-305. Epub 2018 Oct 25.

Department of Surgery, Stanford University School of Medicine, Stanford, California.

Chronic wounds are a significant medical and economic problem worldwide. Individuals over the age of 65 are particularly vulnerable to pressure ulcers and impaired wound healing. With this demographic growing rapidly, there is a need for effective treatments. We have previously demonstrated that defective hypoxia signaling through destabilization of the master hypoxia-inducible factor 1α (HIF-1α) underlies impairments in both aging and diabetic wound healing. To stabilize HIF-1α, we developed a transdermal delivery system of the Food and Drug Administration-approved small molecule deferoxamine (DFO) and found that transdermal DFO could both prevent and treat ulcers in diabetic mice. Here, we demonstrate that transdermal DFO can similarly prevent pressure ulcers and normalize aged wound healing. Enhanced wound healing by DFO is brought about by stabilization of HIF-1α and improvements in neovascularization. Transdermal DFO can be rapidly translated into the clinic and may represent a new approach to prevent and treat pressure ulcers in aged patients.
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http://dx.doi.org/10.1111/wrr.12667DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6238634PMC
May 2018

Controlled Delivery of a Focal Adhesion Kinase Inhibitor Results in Accelerated Wound Closure with Decreased Scar Formation.

J Invest Dermatol 2018 11 12;138(11):2452-2460. Epub 2018 Jul 12.

Hagey Laboratory for Pediatric Regenerative Medicine, Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford University School of Medicine, Stanford, California, USA. Electronic address:

Formation of scars after wounding or trauma represents a significant health care burden costing the economy billions of dollars every year. Activation of focal adhesion kinase (FAK) has been shown to play a pivotal role in transducing mechanical signals to elicit fibrotic responses and scar formation during wound repair. We have previously shown that inhibition of FAK using local injections of a small molecule FAK inhibitor (FAKI) can attenuate scar development in a hypertrophic scar model. Clinical translation of FAKI therapy has been challenging, however, because of the lack of an effective drug delivery system for extensive burn injuries, blast injuries, and large excisional injuries. To address this issue, we have developed a pullulan collagen-based hydrogel to deliver FAKI to excisional and burn wounds in mice. Specifically, two distinct drug-laden hydrogels were developed for rapid or sustained release of FAKI for treatment of burn wounds and excisional wounds, respectively. Controlled delivery of FAKI via pullulan collagen hydrogels accelerated wound healing and reduced collagen deposition and activation of scar-forming myofibroblasts in both wound healing models. Our study highlights a biomaterial-based drug delivery approach for wound and scar management that has significant translational implications.
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http://dx.doi.org/10.1016/j.jid.2018.04.034DOI Listing
November 2018

Strategies for directing cells into building functional hearts and parts.

Biomater Sci 2018 Jun;6(7):1664-1690

School of Chemical Engineering, College of Engineering, University of Tehran, Iran.

The increasing population of patients with heart disease and the limited availability of organs for transplantation have encouraged multiple strategies to fabricate healthy implantable cardiac tissues. One of the main challenges in cardiac tissue engineering is to direct cell behaviors to form functional three-dimensional (3D) biomimetic constructs. This article provides a brief review on various cell sources used in cardiac tissue engineering and highlights the effect of scaffold-based signals such as topographical and biochemical cues and stiffness. Then, conventional and novel micro-engineered bioreactors for the development of functional cardiac tissues will be explained. Bioreactor-based signals including mechanical and electrical cues to control cardiac cell behavior will also be elaborated in detail. Finally, the application of computational fluid dynamics to design suitable bioreactors will be discussed. This review presents the current state-of-the-art, emerging directions and future trends that critically appraise the concepts involved in various approaches to direct cells for building functional hearts and heart parts.
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http://dx.doi.org/10.1039/c7bm01176hDOI Listing
June 2018

Prolonged survival of transplanted stem cells after ischaemic injury via the slow release of pro-survival peptides from a collagen matrix.

Nat Biomed Eng 2018 Feb 6;2(2):104-113. Epub 2018 Feb 6.

Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, USA.

Stem-cell-based therapies hold considerable promise for regenerative medicine. However, acute donor-cell death within several weeks after cell delivery remains a critical hurdle for clinical translation. Co-transplantation of stem cells with pro-survival factors can improve cell engraftment, but this strategy has been hampered by the typically short half-lives of the factors and by the use of Matrigel and other scaffolds that are not chemically defined. Here, we report a collagen-dendrimer biomaterial crosslinked with pro-survival peptide analogues that adheres to the extracellular matrix and slowly releases the peptides, significantly prolonging stem cell survival in mouse models of ischaemic injury. The biomaterial can serve as a generic delivery system to improve functional outcomes in cell-replacement therapy.
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http://dx.doi.org/10.1038/s41551-018-0191-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5927627PMC
February 2018

PEG/Dextran Double Layer Influences Fe Ion Release and Colloidal Stability of Iron Oxide Nanoparticles.

Sci Rep 2018 03 9;8(1):4286. Epub 2018 Mar 9.

Biomaterials and Advanced Drug Delivery Laboratory, Stanford University School of Medicine, Stanford, CA, 94305, USA.

Despite preliminary confidence on biosafety of polymer coated iron oxide nanoparticles (SPIONs), toxicity concerns have hampered their clinical translation. SPIONs toxicity is known to be due to catalytic activity of their surface and release of toxic Fe ions originating from the core biodegradation, leading to the generation of reactive oxygen species (ROS). Here, we hypothesized that a double-layer polymeric corona comprising of dextran as an interior, and polyethylene glycol (PEG) as an exterior layer better shields the core SPIONs. We found that ROS generation was cell specific and depended on SPIONs concentration, although it was reduced by sufficient PEG immobilization or 100 µM deferoxamine. 24 h following injection, PEGylated samples showed reduction of biodistribution in liver, heterogenous biodistribution profile in spleen, and no influence on NPs blood retention. Sufficient surface masking or administration of deferoxamine could be beneficial strategies in designing and clinical translation of future biomedical SPIONs.
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http://dx.doi.org/10.1038/s41598-018-22644-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5844897PMC
March 2018

Microhemorrhage-associated tissue iron enhances the risk for invasion in a mouse model of airway transplantation.

Sci Transl Med 2018 02;10(429)

Division of Pulmonary and Critical Care Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA.

Invasive pulmonary disease due to the mold can be life-threatening in lung transplant recipients, but the risk factors remain poorly understood. To study this process, we used a tracheal allograft mouse model that recapitulates large airway changes observed in patients undergoing lung transplantation. We report that microhemorrhage-related iron content may be a major determinant of invasion and, consequently, its virulence. Invasive growth was increased during progressive alloimmune-mediated graft rejection associated with high concentrations of ferric iron in the graft. The role of iron in invasive growth was further confirmed by showing that this invasive phenotype was increased in tracheal transplants from donor mice lacking the hemochromatosis gene ( ). The invasive phenotype was also increased in mouse syngrafts treated with topical iron solution and in allograft recipients receiving deferoxamine, a chelator that increases iron bioavailability to the mold. The invasive growth of the iron-intolerant double-knockout mutant (Δ/Δ) was lower than that of the wild-type mold. Alloimmune-mediated microvascular damage and iron overload did not appear to impair the host's immune response. In human lung transplant recipients, positive staining for iron in lung transplant tissue was more commonly seen in endobronchial biopsy sections from transplanted airways than in biopsies from the patients' own airways. Collectively, these data identify iron as a major determinant of invasive growth and a potential target to treat or prevent infections in lung transplant patients.
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http://dx.doi.org/10.1126/scitranslmed.aag2616DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5841257PMC
February 2018

In vitro and in vivo metabolite identification of a novel benzimidazole compound ZLN005 by LC-MS/MS.

Rapid Commun Mass Spectrom 2018 Jan 15. Epub 2018 Jan 15.

Biomaterials and Advance Drug Delivery Lab, School of Medicine, Stanford University, USA.

Rationale: A novel benzimidazole compound ZLN005 was previously identified as a transcriptional activator of peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) in certain metabolic tissues. Upregulation of PGC-1α by ZLN005 has been shown to have beneficial effect in a diabetic mouse model and in a coronary artery disease model in vitro. ZLN005 could also have therapeutic potential in neurodegenerative diseases involving down-regulation of PGC-1α. Given the phenotypic efficacy of ZLN005 in several animal models of human disease, its metabolic profile was investigated to guide the development of novel therapeutics using ZLN005 as the lead compound.

Methods: ZLN005 was incubated with both rat and human liver microsomes and S9 fractions to identify in vitro metabolites. Urine from rats dosed with ZLN005 was used to identify in vivo metabolites. Extracted metabolites were analyzed by LC-MS/MS using a hybrid linear ion trap triple quadrupole mass spectrometer under full scan, enhanced product ion scan, neutral loss scan and precursor scan modes. Metabolites in plasma and brain of ZLN005-treated rats were also profiled using multiple reaction monitoring.

Results: Identified in vitro transformations of ZLN005 include mono- and dihydroxylation, further oxidation to carboxylic acids, and mono-O-glucuronide and sulfate conjugation to hydroxy ZLN005 as well as glutathione conjugation. Identified in vivo metabolites are mainly glucuronide and sulfate conjugates of dihydroxyl, carboxyl, and hydroxy acid of the parent compound. The parent compound as well as several major phase I metabolites were found in rat plasma and brain.

Conclusions: Using both in vitro and in vivo methods, we elucidated the metabolic pathway of ZLN005. Phase I metabolites with hydroxylation and carboxylation, as well as phase II metabolites with glucuronide, sulfate and glutathione conjugation, were identified.
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http://dx.doi.org/10.1002/rcm.8060DOI Listing
January 2018

Delivery of monocyte lineage cells in a biomimetic scaffold enhances tissue repair.

JCI Insight 2017 10 5;2(19). Epub 2017 Oct 5.

Hagey Laboratory for Pediatric Regenerative Medicine, Department of Surgery, Division of Plastic and Reconstructive Surgery, and.

The monocyte lineage is essential to normal wound healing. Macrophage inhibition or knockout in mice results in impaired wound healing through reduced neovascularization, granulation tissue formation, and reepithelialization. Numerous studies have either depleted macrophages or reduced their activity in the context of wound healing. Here, we demonstrate that by increasing the number of macrophages or monocytes in the wound site above physiologic levels via pullulan-collagen composite dermal hydrogel scaffold delivery, the rate of wound healing can be significantly accelerated in both wild-type and diabetic mice, with no adverse effect on the quality of repair. Macrophages transplanted onto wounds differentiate into M1 and M2 phenotypes of different proportions at various time points, ultimately increasing angiogenesis. Given that monocytes can be readily isolated from peripheral blood without in vitro manipulation, these findings hold promise for translational medicine aimed at accelerating wound healing across a broad spectrum of diseases.
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http://dx.doi.org/10.1172/jci.insight.96260DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5841872PMC
October 2017

Endothelial APLNR regulates tissue fatty acid uptake and is essential for apelin's glucose-lowering effects.

Sci Transl Med 2017 Sep;9(407)

Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Yale School of Medicine, New Haven, CT 06511, USA.

Treatment of type 2 diabetes mellitus continues to pose an important clinical challenge, with most existing therapies lacking demonstrable ability to improve cardiovascular outcomes. The atheroprotective peptide apelin (APLN) enhances glucose utilization and improves insulin sensitivity. However, the mechanism of these effects remains poorly defined. We demonstrate that the expression of APLNR (APJ/AGTRL1), the only known receptor for apelin, is predominantly restricted to the endothelial cells (ECs) of multiple adult metabolic organs, including skeletal muscle and adipose tissue. Conditional endothelial-specific deletion of ( ) resulted in markedly impaired glucose utilization and abrogation of apelin-induced glucose lowering. Furthermore, we identified inactivation of Forkhead box protein O1 (FOXO1) and inhibition of endothelial expression of fatty acid (FA) binding protein 4 (FABP4) as key downstream signaling targets of apelin/APLNR signaling. Both the and mice demonstrated increased endothelial FABP4 expression and excess tissue FA accumulation, whereas concurrent endothelial deletion or pharmacologic FABP4 inhibition rescued the excess FA accumulation phenotype of the mice. The impaired glucose utilization in the mice was associated with excess FA accumulation in the skeletal muscle. Treatment of these mice with an FABP4 inhibitor abrogated these metabolic phenotypes. These findings provide mechanistic insights that could greatly expand the therapeutic repertoire for type 2 diabetes and related metabolic disorders.
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http://dx.doi.org/10.1126/scitranslmed.aad4000DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5703224PMC
September 2017