Publications by authors named "Indranil Sinha"

110 Publications

High-dimensional profiling reveals phenotypic heterogeneity and disease-specific alterations of granulocytes in COVID-19.

Proc Natl Acad Sci U S A 2021 10;118(40)

Department of Infectious Diseases, Karolinska University Hospital, 171 77, Stockholm, Sweden.

Since the outset of the COVID-19 pandemic, increasing evidence suggests that the innate immune responses play an important role in the disease development. A dysregulated inflammatory state has been proposed as a key driver of clinical complications in COVID-19, with a potential detrimental role of granulocytes. However, a comprehensive phenotypic description of circulating granulocytes in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected patients is lacking. In this study, we used high-dimensional flow cytometry for granulocyte immunophenotyping in peripheral blood collected from COVID-19 patients during acute and convalescent phases. Severe COVID-19 was associated with increased levels of both mature and immature neutrophils, and decreased counts of eosinophils and basophils. Distinct immunotypes were evident in COVID-19 patients, with altered expression of several receptors involved in activation, adhesion, and migration of granulocytes (e.g., CD62L, CD11a/b, CD69, CD63, CXCR4). Paired sampling revealed recovery and phenotypic restoration of the granulocytic signature in the convalescent phase. The identified granulocyte immunotypes correlated with distinct sets of soluble inflammatory markers, supporting pathophysiologic relevance. Furthermore, clinical features, including multiorgan dysfunction and respiratory function, could be predicted using combined laboratory measurements and immunophenotyping. This study provides a comprehensive granulocyte characterization in COVID-19 and reveals specific immunotypes with potential predictive value for key clinical features associated with COVID-19.
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http://dx.doi.org/10.1073/pnas.2109123118DOI Listing
October 2021

printing of growth factor-eluting adhesive scaffolds improves wound healing.

Bioact Mater 2022 Feb 5;8:296-308. Epub 2021 Jul 5.

Division of Plastic Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA.

Acute and chronic wounds affect millions of people around the world, imposing a growing financial burden on patients and hospitals. Despite the application of current wound management strategies, the physiological healing process is disrupted in many cases, resulting in impaired wound healing. Therefore, more efficient and easy-to-use treatment modalities are needed. In this study, we demonstrate the benefit of printed, growth factor-eluting adhesive scaffolds for the treatment of full-thickness wounds in a porcine model. A custom-made handheld printer is implemented to finely print gelatin-methacryloyl (GelMA) hydrogel containing vascular endothelial growth factor (VEGF) into the wounds. and results show that the GelMA crosslinking induces a strong scaffold adhesion and enables printing on curved surfaces of wet tissues, without the need for any sutures. The scaffold is further shown to offer a sustained release of VEGF, enhancing the migration of endothelial cells . Histological analyses demonstrate that the administration of the VEGF-eluting GelMA scaffolds that remain adherent to the wound bed significantly improves the quality of healing in porcine wounds. The introduced printing strategy for wound healing applications is translational and convenient to use in any place, such as an operating room, and does not require expensive bioprinters or imaging modalities.
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http://dx.doi.org/10.1016/j.bioactmat.2021.06.030DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8427093PMC
February 2022

Dehydro-Tocotrienol-β Counteracts Oxidative-Stress-Induced Diabetes Complications in Mice.

Antioxidants (Basel) 2021 Jul 2;10(7). Epub 2021 Jul 2.

Rolf Luft Research Center for Diabetes and Endocrinology, Department of Molecular Medicine and Surgery, Karolinska Institutet, SE-17177 Stockholm, Sweden.

Hyperglycemia, hyperlipidemia, and adiposity are the main factors that cause inflammation in type 2 diabetes due to excessive ROS production, leading to late complications. To counteract the effects of increased free radical production, we searched for a compound with effective antioxidant properties that can induce coenzyme Q biosynthesis without affecting normal cellular functions. Tocotrienols are members of the vitamin E family, well-known as efficient antioxidants that are more effective than tocopherols. Deh-T3β is a modified form of the naturally occurring tocotrienol-β. The synthesis of this compound involves the sequential modification of geranylgeraniol. In this study, we investigated the effects of this compound in different experimental models of diabetes complications. Deh-T3β was found to possess multifaceted capacities. In addition to enhanced wound healing, deh-T3β improved kidney and liver functions, reduced liver steatosis, and improved heart recovery after ischemia and insulin sensitivity in adipose tissue in a mice model of type 2 diabetes. Deh-T3β exerts these positive effects in several organs of the diabetic mice without reducing the non-fasting blood glucose levels, suggesting that both its antioxidant properties and improvement in mitochondrial function are involved, which are central to reducing diabetes complications.
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http://dx.doi.org/10.3390/antiox10071070DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8301068PMC
July 2021

Muscle Cryoinjury and Quantification of Regenerating Myofibers in Mice.

Bio Protoc 2021 Jun 5;11(11):e4036. Epub 2021 Jun 5.

Department of Plastic Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, USA.

Cryoinjury, or injury due to freezing, is a method of creating reproducible, local injuries in skeletal muscle. This method allows studying the regenerative response following muscle injuries , thus enabling the evaluation of local and systemic factors that influence the processes of myofiber regeneration. Cryoinjuries are applicable to the study of various modalities of muscle injury, particularly non-traumatic and traumatic injuries, without a loss of substantial volume of muscle mass. Cryoinjury requires only simple instruments and has the advantage over other methods that the extent of the lesion can be easily adjusted and standardized according to the duration of contact with the freezing instrument. The regenerative response can be evaluated histologically by the average maturity of regenerating myofibers as indicated by the cross-sectional areas of myofibers with centrally located nuclei. Accordingly, cryoinjury is regarded as one of the most reliable and easily accessible methods for simulating muscle injuries in studies of muscle regeneration.
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http://dx.doi.org/10.21769/BioProtoc.4036DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8250343PMC
June 2021

Exercise-induced gene expression changes in skeletal muscle of old mice.

Genomics 2021 Sep 30;113(5):2965-2976. Epub 2021 Jun 30.

Division of Plastic Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States; Harvard Stem Cell Institute, Cambridge, MA, United States. Electronic address:

Exercise is believed to be beneficial for skeletal muscle functions across all ages. Regimented exercise is often prescribed as an effective treatment/prophylaxis for age-related loss of muscle mass and function, known as sarcopenia, and plays an important role in the maintenance of mobility and functional independence in the elderly. However, response to exercise declines with aging, resulting in limited gain of muscle strength and endurance. These changes likely reflect age-dependent alterations in transcriptional response underlying the muscular adaptation to exercise. The exact changes in gene expression accompanying exercise, however, are largely unknown, and elucidating them is of a great clinical interest for understanding and optimizing the exercise-based therapies for sarcopenia. In order to characterize the exercise-induced transcriptomic changes in aged muscle, a paired-end RNA sequencing was performed on rRNA-depleted total RNA extracted from the gastrocnemius muscles of 24 months-old mice after 8 weeks of regimented exercise (exercise group) or no formal exercise program (sedentary group). Differential gene expression analysis of aged skeletal muscle revealed upregulations in the group of genes involved in neurotransmission and neuroexcitation, as well as equally notable absence of anabolic gene upregulations in the exercise group. In particular, genes encoding the transporters and receptor components of glutaminergic transmission were significantly upregulated in exercised muscles, as exemplified by Gria 1, Gria 2 and Grin2c encoding glutamate receptor 1, 2 and 2C respectively, Grin1 and Grin2b encoding N-methyl-d-aspartate receptors (NMDARs), Nptx1 responsible for glutaminergic receptor clustering, and Slc1a2 and Slc17a7 regulating synaptic uptake of glutamate. These changes were accompanied by an increase in the post-synaptic density of NMDARs and acetylcholine receptors (AChRs), as well as their innervation at neuromuscular junctions (NMJs). These results suggest that neural responses predominate the adaptive response of aged skeletal muscle to exercise, and indicate a possibility that glutaminergic transmission at NMJs may be present and responsible for synaptic protection and neural remodeling accompanying the exercise-induced functional enhancement in aged skeletal muscle. In addition, the absence of upregulations in the anabolic pathways highlights them as the area of potential pharmacological targeting for optimizing exercise-led sarcopenia therapy.
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http://dx.doi.org/10.1016/j.ygeno.2021.06.035DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8403630PMC
September 2021

Effect of collagen and EPS components on the viscoelasticity of biofilms.

Soft Matter 2021 Jun;17(25):6225-6237

Department of Mechanical Engineering, Whitacre College of Engineering, Texas Tech University, Lubbock, TX, USA.

Pseudomonas aeruginosa is an opportunistic pathogen that causes thousands of deaths every year in part due to its ability to form biofilms composed of bacteria embedded in a matrix of self-secreted extracellular polysaccharides (EPS), e-DNA, and proteins. In chronic wounds, biofilms are exposed to the host extracellular matrix, of which collagen is a major component. How bacterial EPS interacts with host collagen and whether this interaction affects biofilm viscoelasticity is not well understood. Since physical disruption of biofilms is often used in their removal, knowledge of collagen's effects on biofilm viscoelasticity may enable new treatment strategies that are better tuned to biofilms growing in host environments. In this work, biofilms are grown in the presence of different concentrations of collagen that mimic in vivo conditions. In order to explore collagen's interaction with EPS, nine strains of P. aeruginosa with different patterns of EPS production were used to grow biofilms. Particle tracking microrheology was used to characterize the mechanical development of biofilms over two days. Collagen is found to decrease biofilm compliance and increase relative elasticity regardless of the EPS present in the system. However, this effect is minimized when biofilms overproduce EPS. Collagen appears to become a de facto component of the EPS, through binding to bacteria or physical entanglement.
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http://dx.doi.org/10.1039/d1sm00463hDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8283923PMC
June 2021

Full facial retransplantation in a female patient-Technical, immunologic, and clinical considerations.

Am J Transplant 2021 May 25. Epub 2021 May 25.

Division of Plastic Surgery, Department of Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.

There is limited experience with facial retransplantation (fRT). We report on the management of facial retransplantation in a facial vascularized composite allotransplant recipient following irreversible allograft loss 88 months after the first transplant. Chronic antibody-mediated rejection and recurrent cellular rejection resulted in a deteriorated first allograft and the patient underwent retransplantation. We summarize the events between the two transplantations, focusing on the final rejection episode. We describe the surgical technique of facial retransplantation, the immunological and psychosocial management, and the 6-month postoperative outcomes. Removal of the old allograft and inset of the new transplant were done in one operation. The donor and recipient were a good immunological match. The procedure was technically complex, requiring more proximal arterial anastomoses and an interposition vein graft. During the first and second transplantation, the facial nerve was coapted at the level of the branches. There was no hyperacute rejection in the immediate postoperative phase. Outcomes 6 months postoperatively are promising. We provide proof-of-concept that facial retransplantation is a viable option for patients who suffer irreversible facial vascularized composite allograft loss.
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http://dx.doi.org/10.1111/ajt.16696DOI Listing
May 2021

Blocking Fra-1 sensitizes triple-negative breast cancer to PARP inhibitor.

Cancer Lett 2021 05 27;506:23-34. Epub 2021 Feb 27.

Department of Biosciences and Nutrition, Karolinska Institutet, S-141 83 Huddinge, Sweden; Science for Life Laboratory, Department of Protein Science, CBH, KTH Royal Institute of Technology, Solna, Sweden. Electronic address:

The AP-1 member Fra-1 is overexpressed in TNBC and plays crucial roles in tumor progression and treatment resistance. In a previous large-scale screen, we identified PARP1 to be among 118 proteins that interact with endogenous chromatin-bound Fra-1 in TNBC cells. PARP1 inhibitor (olaparib) is currently in clinical use for treatment of BRCA-mutated TNBC breast cancer. Here, we demonstrate that the Fra-1-PARP1 interaction impacts the efficacy of olaparib treatment. We show that PARP1 interacts with and downregulates Fra-1, thereby reducing AP-1 transcriptional activity. Olaparib treatment, or silencing of PARP1, consequently, increases Fra-1 levels and enhances its transcriptional activity. Increased Fra-1 can have adverse effect, including treatment resistance. We also found that a large fraction of PARP1-regulated genes was dependent on Fra-1. We show that by inhibiting Fra-1/AP-1, non-BRCA-mutated TNBC cells can become sensitized to olaparib treatment. We identify that high PARP1 expression is indicative of a poor clinical outcome in breast cancer patients overall (P = 0.01), but not for HER-2 positive patients. In conclusion, by exploring the functionality of the Fra-1 and PARP1 interaction, we propose that targeting Fra-1 could serve as a combinatory therapeutic approach to improve olaparib treatment outcome for TNBC patients.
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http://dx.doi.org/10.1016/j.canlet.2021.02.018DOI Listing
May 2021

In Vivo Printing of Nanoenabled Scaffolds for the Treatment of Skeletal Muscle Injuries.

Adv Healthc Mater 2021 05 28;10(10):e2002152. Epub 2021 Feb 28.

Department of Mechanical and Materials Engineering, University of Nebraska, Lincoln, NE, 68588, USA.

Extremity skeletal muscle injuries result in substantial disability. Current treatments fail to recoup muscle function, but properly designed and implemented tissue engineering and regenerative medicine techniques can overcome this challenge. In this study, a nanoengineered, growth factor-eluting bioink that utilizes Laponite nanoclay for the controlled release of vascular endothelial growth factor (VEGF) and a GelMA hydrogel for a supportive and adhesive scaffold that can be crosslinked in vivo is presented. The bioink is delivered with a partially automated handheld printer for the in vivo formation of an adhesive and 3D scaffold. The effect of the controlled delivery of VEGF alone or paired with adhesive, supportive, and fibrilar architecture has not been studied in volumetric muscle loss (VML) injuries. Upon direct in vivo printing, the constructs are adherent to skeletal muscle and sustained release of VEGF. The in vivo printing of muscle ink in a murine model of VML injury promotes functional muscle recovery, reduced fibrosis, and increased anabolic response compared to untreated mice. The in vivo construction of a therapeutic-eluting 3D scaffold paves the way for the immediate treatment of a variety of soft tissue traumas.
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http://dx.doi.org/10.1002/adhm.202002152DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8137605PMC
May 2021

Miniaturized Needle Array-Mediated Drug Delivery Accelerates Wound Healing.

Adv Healthc Mater 2021 04 15;10(8):e2001800. Epub 2021 Feb 15.

Department of Biomedical Engineering, University of Connecticut, Farmington, CT, 06030, USA.

A major impediment preventing normal wound healing is insufficient vascularization, which causes hypoxia, poor metabolic support, and dysregulated physiological responses to injury. To combat this, the delivery of angiogenic factors, such as vascular endothelial growth factor (VEGF), has been shown to provide modest improvement in wound healing. Here, the importance of specialty delivery systems is explored in controlling wound bed drug distribution and consequently improving healing rate and quality. Two intradermal drug delivery systems, miniaturized needle arrays (MNAs) and liquid jet injectors (LJIs), are evaluated to compare effective VEGF delivery into the wound bed. The administered drug's penetration depth and distribution in tissue are significantly different between the two technologies. These systems' capability for efficient drug delivery is first confirmed in vitro and then assessed in vivo. While topical administration of VEGF shows limited effectiveness, intradermal delivery of VEGF in a diabetic murine model accelerates wound healing. To evaluate the translational feasibility of the strategy, the benefits of VEGF delivery using MNAs are assessed in a porcine model. The results demonstrate enhanced angiogenesis, reduced wound contraction, and increased regeneration. These findings show the importance of both therapeutics and delivery strategy in wound healing.
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http://dx.doi.org/10.1002/adhm.202001800DOI Listing
April 2021

The Plastic Surgeon's Role in the COVID-19 Crisis: Regarding Domestic Violence.

Cureus 2021 Jan 12;13(1):e12650. Epub 2021 Jan 12.

Division of Plastic and Reconstructive Surgery, Brigham and Women's Hospital, Boston, USA.

Pandemics are associated with increased rates of intimate partner violence (IPV). IPV-related physical abuse is most commonly inflicted through craniofacial assault and upper extremity injury. Plastic surgeons are frequently consulted for recommendations in the management of head-and-neck and hand trauma, thereby are uniquely positioned to encounter patients who have experienced IPV. However, IPV training is not routinely offered in surgical education. We provide a review of the increasing prevalence of IPV during the COVID-19 pandemic and its pertinence to plastic surgery consultation in the emergency room. This article aims to increase providers' confidence in recognizing IPV-suspicious injuries and propose an educational, interactive tool for discussing IPV with patients.
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http://dx.doi.org/10.7759/cureus.12650DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7872873PMC
January 2021

Major alterations in the mononuclear phagocyte landscape associated with COVID-19 severity.

Proc Natl Acad Sci U S A 2021 02;118(6)

Center for Infectious Medicine, Department of Medicine Huddinge, Karolinska Institutet, Karolinska University Hospital, 171 77 Stockholm, Sweden.

Dendritic cells (DCs) and monocytes are crucial mediators of innate and adaptive immune responses during viral infection, but misdirected responses by these cells may contribute to immunopathology. Here, we performed high-dimensional flow cytometry-analysis focusing on mononuclear phagocyte (MNP) lineages in SARS-CoV-2-infected patients with moderate and severe COVID-19. We provide a deep and comprehensive map of the MNP landscape in COVID-19. A redistribution of monocyte subsets toward intermediate monocytes and a general decrease in circulating DCs was observed in response to infection. Severe disease coincided with the appearance of monocytic myeloid-derived suppressor cell-like cells and a higher frequency of pre-DC2. Furthermore, phenotypic alterations in MNPs, and their late precursors, were cell-lineage-specific and associated either with the general response against SARS-CoV-2 or COVID-19 severity. This included an interferon-imprint in DC1s observed in all patients and a decreased expression of the coinhibitory molecule CD200R in pre-DCs, DC2s, and DC3 subsets of severely sick patients. Finally, unsupervised analysis revealed that the MNP profile, alone, pointed to a cluster of COVID-19 nonsurvivors. This study provides a reference for the MNP response to SARS-CoV-2 infection and unravels mononuclear phagocyte dysregulations associated with severe COVID-19.
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http://dx.doi.org/10.1073/pnas.2018587118DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8017719PMC
February 2021

Loss of ARNT in skeletal muscle limits muscle regeneration in aging.

FASEB J 2020 12 8;34(12):16086-16104. Epub 2020 Oct 8.

Division of Plastic Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.

The ability of skeletal muscle to regenerate declines significantly with aging. The expression of aryl hydrocarbon receptor nuclear translocator (ARNT), a critical component of the hypoxia signaling pathway, was less abundant in skeletal muscle of old (23-25 months old) mice. This loss of ARNT was associated with decreased levels of Notch1 intracellular domain (N1ICD) and impaired regenerative response to injury in comparison to young (2-3 months old) mice. Knockdown of ARNT in a primary muscle cell line impaired differentiation in vitro. Skeletal muscle-specific ARNT deletion in young mice resulted in decreased levels of whole muscle N1ICD and limited muscle regeneration. Administration of a systemic hypoxia pathway activator (ML228), which simulates the actions of ARNT, rescued skeletal muscle regeneration in both old and ARNT-deleted mice. These results suggest that the loss of ARNT in skeletal muscle is partially responsible for diminished myogenic potential in aging and activation of hypoxia signaling holds promise for rescuing regenerative activity in old muscle.
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http://dx.doi.org/10.1096/fj.202000761RRDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7756517PMC
December 2020

Optimizing Skeletal Muscle Anabolic Response to Resistance Training in Aging.

Front Physiol 2020 23;11:874. Epub 2020 Jul 23.

Division of Plastic Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States.

Loss of muscle mass and strength with aging, also termed sarcopenia, results in a loss of mobility and independence. Exercise, particularly resistance training, has proven to be beneficial in counteracting the aging-associated loss of skeletal muscle mass and function. However, the anabolic response to exercise in old age is not as robust, with blunted improvements in muscle size, strength, and function in comparison to younger individuals. This review provides an overview of several physiological changes which may contribute to age-related loss of muscle mass and decreased anabolism in response to resistance training in the elderly. Additionally, the following supplemental therapies with potential to synergize with resistance training to increase muscle mass are discussed: nutrition, creatine, anti-inflammatory drugs, testosterone, and growth hormone (GH). Although these interventions hold some promise, further research is necessary to optimize the response to exercise in elderly patients.
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http://dx.doi.org/10.3389/fphys.2020.00874DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7390896PMC
July 2020

The Feasibility of Host Transcriptome Profiling as a Diagnostic Tool for Microbial Etiology in Childhood Cancer Patients with Febrile Neutropenia.

Int J Mol Sci 2020 Jul 26;21(15). Epub 2020 Jul 26.

Department of Medicine Solna, Infectious Disease Unit, Center for Molecular Medicine, Karolinska University Hospital, Karolinska Institutet, 171 76 Stockholm, Sweden.

Infection is a common and serious complication of cancer treatment in children that often presents as febrile neutropenia (FN). Gene-expression profiling techniques can reveal transcriptional signatures that discriminate between viral, bacterial and asymptomatic infections in otherwise healthy children. Here, we examined whether gene-expression profiling was feasible in children with FN who were undergoing cancer treatment. The blood transcriptome of the children ( = 63) was investigated at time of FN diagnosed as viral, bacterial, co-infection or unknown etiology, respectively, and compared to control samples derived from 12 of the patients following the FN episode. RNA sequencing was successful in 43 (68%) of the FN episodes. Only two genes were significantly differentially expressed in the bacterial versus the control group. Significantly up-regulated genes in patients with the other three etiologies versus the control group were enriched with cellular processes related to proliferation and cellular stress response, with no clear enrichment with innate responses to pathogens. Among the significantly down-regulated genes, a few clustered into pathways connected to responses to infection. In the present study of children during cancer treatment, the blood transcriptome was not suitable for determining the etiology of FN because of too few circulating immune cells for reliable gene expression analysis.
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http://dx.doi.org/10.3390/ijms21155305DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7432212PMC
July 2020

Adult-Onset Myopathy with Constitutive Activation of Akt following the Loss of hnRNP-U.

iScience 2020 Jul 29;23(7):101319. Epub 2020 Jun 29.

Department of Orthopaedic Surgery, Brigham and Women's Hospital, Harvard Medical School, 75 Francis Street, Boston, MA 02115, USA. Electronic address:

Skeletal muscle has the remarkable ability to modulate its mass in response to changes in nutritional input, functional utilization, systemic disease, and age. This is achieved by the coordination of transcriptional and post-transcriptional networks and the signaling cascades balancing anabolic and catabolic processes with energy and nutrient availability. The extent to which alternative splicing regulates these signaling networks is uncertain. Here we investigate the role of the RNA-binding protein hnRNP-U on the expression and splicing of genes and the signaling processes regulating skeletal muscle hypertrophic growth. Muscle-specific Hnrnpu knockout (mKO) mice develop an adult-onset myopathy characterized by the selective atrophy of glycolytic muscle, the constitutive activation of Akt, increases in cellular and metabolic stress gene expression, and changes in the expression and splicing of metabolic and signal transduction genes. These findings link Hnrnpu with the balance between anabolic signaling, cellular and metabolic stress, and physiological growth.
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http://dx.doi.org/10.1016/j.isci.2020.101319DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7358745PMC
July 2020

Srebf1 Controls Midbrain Dopaminergic Neurogenesis.

Cell Rep 2020 05;31(5):107601

Laboratory for Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Biomedicum, Solnavägen 9, 17177 Stockholm, Sweden. Electronic address:

Liver X receptors (LXRs) and their ligands are potent regulators of midbrain dopaminergic (mDA) neurogenesis and differentiation. However, the molecular mechanisms by which LXRs control these functions remain to be elucidated. Here, we perform a combined transcriptome and chromatin immunoprecipitation sequencing (ChIP-seq) analysis of midbrain cells after LXR activation, followed by bioinformatic analysis to elucidate the transcriptional networks controlling mDA neurogenesis. Our results identify the basic helix-loop-helix transcription factor sterol regulatory element binding protein 1 (SREBP1) as part of a cluster of proneural transcription factors in radial glia and as a regulator of transcription factors controlling mDA neurogenesis, such as Foxa2. Moreover, loss- and gain-of-function experiments in vitro and in vivo demonstrate that Srebf1 is both required and sufficient for mDA neurogenesis. Our data, thus, identify Srebf1 as a central player in mDA neurogenesis.
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http://dx.doi.org/10.1016/j.celrep.2020.107601DOI Listing
May 2020

A porous collagen-GAG scaffold promotes muscle regeneration following volumetric muscle loss injury.

Wound Repair Regen 2020 01 7;28(1):61-74. Epub 2019 Nov 7.

Division of Plastic Surgery, Brigham and Women's Hospital, Boston, Massachusetts.

Volumetric muscle loss (VML) is a segmental loss of skeletal muscle which commonly heals with fibrosis, minimal muscle regeneration, and loss of muscle strength. Treatment options for these wounds which promote functional recovery are currently lacking. This study was designed to investigate whether the collagen-GAG scaffold (CGS) promotes functional muscle recovery following VML. A total of 66 C57/Bl6 mice were used in a three-stage experiment. First, 24 animals were split into three groups which underwent sham injury or unilateral quadriceps VML injury with or without CGS implantation. Two weeks post-surgery, muscle was harvested for histological and gene expression analysis. In the second stage, 18 mice underwent bilateral quadriceps VML injury, followed by weekly functional testing using a treadmill. In the third stage, 24 mice underwent sham or bilateral quadriceps VML injury with or without CGS implantation, with tissue harvested six weeks post-surgery for histological and gene expression analysis. VML mice treated with CGS demonstrated increased remnant fiber hypertrophy versus both the VML with no CGS and uninjured groups. Both VML groups showed greater muscle fiber hypertrophy than non-injured muscle. This phenomenon was still evident in the longer-term experiment. The gene array indicated that the CGS promoted upregulation of factors involved in promoting wound healing and regeneration. In terms of functional improvement, the VML mice treated with CGS ran at higher maximum speeds than VML without CGS. A CGS was shown to enhance muscle hypertrophy in response to VML injury with a resultant improvement in functional performance. A gene array highlighted increased gene expression of multiple growth factors following CGS implantation. This suggests that implantation of a CGS could be a promising treatment for VML wounds.
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http://dx.doi.org/10.1111/wrr.12768DOI Listing
January 2020

Endogenous interaction profiling identifies DDX5 as an oncogenic coactivator of transcription factor Fra-1.

Oncogene 2019 07 23;38(28):5725-5738. Epub 2019 Apr 23.

Department of Biosciences and Nutrition, Karolinska Institutet, S-141 83, Huddinge, Sweden.

Fra-1, a member of the activator protein 1 (AP-1) family, is overexpressed in triple-negative breast cancer (TNBC) and plays crucial roles in tumor growth. Here we report the identification of 118 proteins interacting with endogenous chromatin-bound Fra-1 in TNBC cells, highlighting DDX5 as the most enriched Fra-1-interacting protein. DDX5, a previously unrecognized protein in the Fra-1 transcriptional network, shows extensive overlap with Fra-1 cistrome and transcriptome that are highly associated with the TNBC cell growth. We provide evidence that DDX5 expression enhances Fra-1 transcriptional activity and potentiates Fra-1-driven cell proliferation. Furthermore, we show that the DDX5 target gene signature predicts poor clinical outcome in breast cancer patients. DDX5 protein level was higher in triple-negative basal-like tumors than in non-basal-like tumors, including luminal A, luminal B, and HER2-enriched subtypes. Collectively, by combining proteomic and genomic approaches we reveal a role for DDX5 as a regulatory protein of Fra-1 signaling and suggest DDX5 as a potential therapeutic target for TNBC.
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http://dx.doi.org/10.1038/s41388-019-0824-4DOI Listing
July 2019

Implications of Aging in Plastic Surgery.

Plast Reconstr Surg Glob Open 2019 Jan 14;7(1):e2085. Epub 2019 Jan 14.

Division of Plastic Surgery, Brigham and Women's Hospital, Boston, Mass.

Given the rapidly aging population, investigating the effect of age on plastic surgery outcomes is imperative. Despite this, the topic has received relatively little attention. Furthermore, there appears to be little integration between the basic scientists investigating the mechanisms of aging and the plastic surgeons providing the majority of "antiaging" therapies. This review first provides a description of the effects and mechanisms of aging in 5 types of tissue: skin, adipose tissue, muscles, bones and tendons, and nervous tissue followed by an overview of the basic mechanisms underlying aging, presenting the currently proposed cellular and molecular theories. Finally, the impact of aging, as well as frailty, on plastic surgery outcomes is explored by focusing on 5 different topics: general wound healing and repair of cutaneous tissue, reconstruction of soft tissue, healing of bones and tendons, healing of peripheral nerves, and microsurgical reconstruction. We find mixed reports on the effect of aging or frailty on outcomes in plastic surgery, which we hypothesize to be due to exclusion of aged and frail patients from surgery as well as due to outcomes that reported no postsurgical issues with aged patients. As plastic surgeons continue to interact more with the growing elderly population, a better appreciation of the underlying mechanisms and outcomes related to aging and a clear distinction between chronological age and frailty can promote better selection of patients, offering appropriate patients surgery to improve an aged appearance, and declining interventions in inappropriate patients.
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http://dx.doi.org/10.1097/GOX.0000000000002085DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6382222PMC
January 2019

Nuclear localized Akt limits skeletal muscle derived fibrotic signaling.

Biochem Biophys Res Commun 2019 01 7;508(3):838-843. Epub 2018 Dec 7.

Department of Orthopedic Surgery, Boston, MA, USA. Electronic address:

Skeletal muscle regeneration following injury is a complex multi-stage process involving the recruitment of inflammatory cells, the activation of muscle resident fibroblasts, and the differentiation of activated myoblasts into myocytes. Dysregulation of these cellular processes is associated with ineffective myofiber repair and excessive deposition of extracellular matrix proteins leading to fibrosis. PI3K/Akt signaling is a critical integrator of intra- and intercellular signals connecting nutrient availability to cell survival and growth. Activation of the PI3K/Akt pathway in skeletal muscle leads to hypertrophic growth and a reversal of the changes in body composition associated with obesity and advanced age. Though the molecular mechanisms mediating these effects are incompletely understood, changes in paracrine signaling are thought to play a key role. Here, we utilized modified RNA to study the biological role of the transient translocation of Akt to the myonuclei of maturing myotubes. Using a conditioned medium model system, we show that ectopic myonuclear Akt suppresses fibrogenic paracrine signaling in response to oxidative stress, and that interventions that increase or restore myonuclear Akt may impair fibrosis.
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http://dx.doi.org/10.1016/j.bbrc.2018.11.202DOI Listing
January 2019

Reduced Hypoxia-Related Genes in Porcine Limbs in Ex Vivo Hypothermic Perfusion Versus Cold Storage.

J Surg Res 2018 12 4;232:137-145. Epub 2018 Jul 4.

Division of Plastic Surgery, Department of Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA. Electronic address:

Background: Ischemia-reperfusion injury remains the major limiting factor for limb replantation and transplantation. Static cold storage (SCS) on ice currently represents the standard mode of preservation but is limited to 6 h of duration. Ex vivo machine perfusion has evolved as a potential alternative to safely extend the duration of ex vivo preservation by providing continuous supply of oxygen and nutrients. This study aims to evaluate underlying molecular mechanisms of both preservation modalities.

Methods: We assessed molecular changes in amputated porcine forelimbs stored on ice at 4°C for 2 h (n = 2) and limbs perfused with Perfadex solution at 10°C for 2 h (n = 3) or 12 h (n = 3) before replantation. Muscle biopsies were examined for histological changes and gene expression levels using H&E staining and a hypoxia-related PCR gene array, respectively.

Results: Histology revealed only minor differences between the ice (SCS) and perfusion groups after 2 h of preservation, with decreased muscle fiber disruption in the perfusion groups compared with the ice (SCS) group. Perfused limbs demonstrated downregulation of genes coding for glycolytic pathways and glucose transporters after 2 h and 12 h when compared with SCS after 2 h. Similarly, genes that induce angiogenesis and those that are activated on DNA damage were downregulated in both perfusion groups as compared with SCS.

Conclusions: Perfusion of porcine limbs resulted in less activation of hypoxia-related gene families when compared with SCS. This may indicate a state more closely resembling physiological conditions during perfusion and potentially limiting ischemic injury. Our study confirms ex vivo perfusion for up to 12 h as a viable alternative for preservation of vascularized composite tissues.
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http://dx.doi.org/10.1016/j.jss.2018.05.067DOI Listing
December 2018

Meta-analysis and Systematic Review of Skin Graft Donor-site Dressings with Future Guidelines.

Plast Reconstr Surg Glob Open 2018 Sep 24;6(9):e1928. Epub 2018 Sep 24.

Department of Surgery, Division of Plastic Surgery, Brigham & Women's Hospital, Harvard Medical School, Boston, Mass.

Background: Many types of split-thickness skin graft (STSG) donor-site dressings are available with little consensus from the literature on the optimal dressing type. The purpose of this systematic review was to analyze the most recent outcomes regarding moist and nonmoist dressings for STSG donor sites.

Methods: A comprehensive systematic review was conducted across PubMed/MEDLINE, EMBASE, and Cochrane Library databases to search for comparative studies evaluating different STSG donor-site dressings in adult subjects published between 2008 and 2017. The quality of randomized controlled trials was assessed using the Jadad scale. Data were collected on donor-site pain, rate of epithelialization, infection rate, cosmetic appearance, and cost. Meta-analysis was performed for reported pain scores.

Results: A total of 41 articles were included comparing 44 dressings. Selected studies included analysis of donor-site pain (36 of 41 articles), rate of epithelialization (38 of 41), infection rate (25 of 41), cosmetic appearance (20 of 41), and cost (10 of 41). Meta-analysis revealed moist dressings result in lower pain (pooled effect size = 1.44). A majority of articles (73%) reported better reepithelialization rates with moist dressings.

Conclusion: The literature on STSG donor-site dressings has not yet identified an ideal dressing. Although moist dressings provide superior outcomes with regard to pain control and wound healing, there continues to be a lack of standardization. The increasing commercial availability and marketing of novel dressings necessitates the development of standardized research protocols to design better comparison studies and assess true efficacy.
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http://dx.doi.org/10.1097/GOX.0000000000001928DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6191241PMC
September 2018

Noninvasive Flap Preconditioning by Foam-Mediated External Suction Improves the Survival of Fasciocutaneous Axial-Pattern Flaps in a Type 2 Diabetic Murine Model.

Plast Reconstr Surg 2018 12;142(6):872e-883e

From the Division of Plastic Surgery, Department of Surgery, Brigham and Women's Hospital, Harvard Medical School; the Department of Plastic and Reconstructive Surgery, Hand Surgery-Burn Center, University Hospital of the RWTH Aachen; the Institute of Functional and Clinical Anatomy, University Medical Center of the Johannes Gutenberg University; and the Institute of Pathology, Heinrich Heine University and University Hospital.

Background: Advances in reconstructive surgery are leading to an increased number of flaps at risk for ischemic necrosis, because of either intrinsic (e.g., larger flap size) or extrinsic (e.g., diabetes) factors. Methods to preoperatively improve flap vascularity and limit postoperative ischemia are lacking. Noninvasive suction, using either a macrodeformational silicone cup interface (external volume expansion) or a microdeformational polyurethane foam interface (foam-mediated external volume expansion), has been shown to induce angiogenesis in tissues. The authors investigated whether the preoperative use of external volume expansion/foam-mediated external volume expansion improves flap survival in an obesity-induced diabetic animal model.

Methods: Db/Db mice underwent either mechanical stimulation with suction for 5 days using either external volume expansion or foam-mediated external volume expansion, or received no stimulation (n = 8 per group). Five days after the last stimulation, a critical-size, axial-pattern, fasciocutaneous flap was raised in all animals. Postoperatively, flap survival was monitored with digital imaging for 10 days. After this period, flaps were harvested to assess tissue survival, angiogenesis, and inflammation, using histology and polymerase chain reaction.

Results: Foam-mediated external volume expansion preconditioning significantly increased the viable flap area (28 percent), viable flap volume (27 percent), and flap capillary density (36 percent) in comparison to controls; vascular endothelial growth factor was also up-regulated (>300 percent). In contrast, external volume expansion resulted in a severe inflammatory response and increased flap necrosis.

Conclusions: Foam-mediated external volume expansion improves flap survival in obese diabetic mice. This procedure may allow for improved clinical rates of flap survival in high-risk patients.
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http://dx.doi.org/10.1097/PRS.0000000000005038DOI Listing
December 2018

Use of a novel chitosan-based dressing on split-thickness skin graft donor sites: a pilot study.

J Wound Care 2018 Jul;27(Sup7):S12-S18

Plastic Surgeon Division of Plastic Surgery, Brigham and Women's Hospital, Boston, US., Harvard Medical School, Boston, US.

Objective: Split-thickness skin graft (STSG) donor site dressings can play an integral role in reducing donor site morbidity. This study tested a novel, chitosan-based wound dressing, Opticell Ag, as an STSG donor site dressing for wounds <10% total body surface area (TBSA).

Method: Between January and December 2016, the chitosan-based dressing was placed on participating patients' donor sites immediately following graft harvest and covered with a transparent occlusive dressing. Pain was evaluated on postoperative day one, before dressing change between days 5-7, and before and after dressing removal between days 10-14 using the Visual Analog Scale (VAS). The extent of re-epithelialisation was determined between day 10-14 and at one month, and healing quality was also evaluated at one month post-operatively using the Vancouver Scar Scale (VSS).

Results: A total of 19 patients were recruited, of which 16 completed the study. Patients experienced mild-to-moderate pain in their donor sites when the chitosan-based dressing was used. Pain decreased significantly between postoperative day one and days 10-14, as well as between days 5-7 and 10-14. The mean percentage of re-epithelialisation on days 10-14 was 92% and by one month was 99%. The mean VSS at one month was 3.2±1.4. There were no statistically significant differences between patients' re-epithelialisation rates or VSS scores. There were unplanned dressing changes in four patients. No donor site infections or other adverse events were identified.

Conclusion: The chitosan-based dressing tested in this study is safe, effective, and associated with reasonable pain control and acceptable healing quality. The results suggest that it is a promising STSG donor site dressing.
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http://dx.doi.org/10.12968/jowc.2018.27.Sup7.S12DOI Listing
July 2018

Evaluation of the efficacy of cell and micrograft transplantation for full-thickness wound healing.

J Surg Res 2018 07 6;227:35-43. Epub 2018 Mar 6.

Division of Plastic Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts. Electronic address:

Background: Skin grafting is the current standard of care in the treatment of full-thickness burns and other wounds. It is sometimes associated with substantial problems, such as poor quality of the healed skin, scarring, and lack of donor-site skin in large burns. To overcome these problems, alternative techniques that could provide larger expansion of a skin graft have been introduced over the years. Particularly, different cell therapies and methods to further expand skin grafts to minimize the need for donor skin have been attempted. The purpose of this study was to objectively evaluate the efficacy of cell and micrograft transplantation in the healing of full-thickness wounds.

Materials And Methods: Allogeneic cultured keratinocytes and fibroblasts, separately and together, as well as autologous and allogeneic skin micrografts were transplanted to full-thickness rat wounds, and healing was studied over time. In addition, wound fluid was collected, and the level of various cytokines and growth factors in the wound after transplantation was measured.

Results: Our results showed that both autologous and allogeneic micrografts were efficient treatment modalities for full-thickness wound healing. Allogeneic skin cell transplantation did not result in wound closure, and no viable cells were found in the wound 10 d after transplantation.

Conclusions: Our study demonstrated that allogeneic micrografting is a possible treatment modality for full-thickness wound healing. The allografts stayed viable in the wound and contributed to both re-epithelialization and formation of dermis, whereas allogeneic skin cell transplantation did not result in wound closure.
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http://dx.doi.org/10.1016/j.jss.2018.02.004DOI Listing
July 2018

Patient-Specific Bioinks for 3D Bioprinting of Tissue Engineering Scaffolds.

Adv Healthc Mater 2018 06 16;7(11):e1701347. Epub 2018 Apr 16.

Biomaterials Innovation Research Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02139, USA.

Bioprinting has emerged as a promising tool in tissue engineering and regenerative medicine. Various 3D printing strategies have been developed to enable bioprinting of various biopolymers and hydrogels. However, the incorporation of biological factors has not been well explored. As the importance of personalized medicine is becoming more clear, the need for the development of bioinks containing autologous/patient-specific biological factors for tissue engineering applications becomes more evident. Platelet-rich plasma (PRP) is used as a patient-specific source of autologous growth factors that can be easily incorporated to hydrogels and printed into 3D constructs. PRP contains a cocktail of growth factors enhancing angiogenesis, stem cell recruitment, and tissue regeneration. Here, the development of an alginate-based bioink that can be printed and crosslinked upon implantation through exposure to native calcium ions is reported. This platform can be used for the controlled release of PRP-associated growth factors which may ultimately enhance vascularization and stem cell migration.
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http://dx.doi.org/10.1002/adhm.201701347DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6422175PMC
June 2018

Chemical Transformations in Confined Space of Coordination Architectures.

Inorg Chem 2018 Apr 26;57(8):4205-4221. Epub 2018 Mar 26.

Department of Inorganic and Physical Chemistry , Indian Institute of Science , Bangalore 560012 , India.

The scholastic significance of supramolecular chemistry continues to grow with the recent development of catalytic transformations in confined space of supramolecular architectures. It has come a long way from a natural cavity containing molecules to modern smart materials capable of manipulating reaction pathways. The rise of self-assembled coordination complexes provided a diverse array of host structures. Starting from purely organic compounds to metalloligand surrogates, supramolecular host cavities were tuned according to the requirement of the reactions. The understanding of their participation in a reaction led to better usage of those assemblies for specific reaction sequences. Commencing from cyclodextrin, a wide range of organic molecules was used for cage-catalyzed organic transformations. However, difficulties in synthesis and a tedious purification procedure led chemists to choose a different pathway of metal-ligand coordination-driven self-assembly. The latter stood out as a potential replacement of the organic cages, overcoming the previous drawbacks. In the glut of different transition-metal assemblies used for catalytic transformations, many of them showed chemo- and stereoselective products. However, the small cavity size in some of them led to premature failure of the reaction. In that context, "molecular barrels" showed good efficacy for the catalytic reaction sequence. The large cavity size and bigger orifice for intake of the substrate and easy release of the product made them a better choice for catalysis. Additionally these are mostly used in aqueous media, which reinforces the idea of green and environmentally nonhazardous chemistry. In this Viewpoint, we discuss the use of metal-ligand coordination-driven self-assembled molecular containers used for catalysis with special emphasis on molecular barrels. This paper built on existing literature provides a thorough development of the fertile ground of the coordination architecture for catalysis and its future direction of propagation.
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http://dx.doi.org/10.1021/acs.inorgchem.7b03067DOI Listing
April 2018
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