Sanam Salimi Elizei

Postelectrospinning modifications for alginate nanofiber-based wound dressings

Alginate nanofibers have been attractive for potential tissue regeneration applications due to a combination of their moisture retention ability and large surface area available in a nonwoven nanofiber form. This study aims to address several challenges in alginate nanofiber application, including the lack of structural stability in aqueous environment and limited cell attachment as compared to commercial wound dressings, via examining crosslinking techniques. In addition to the commonly performed divalent ion crosslinking, a glutaraldehyde double-crosslinking step and polylysine addition were applied to an electrospun alginate nanofiber nonwoven mat. With optimization of the electrospinning solution, nanofiber morphology was maintained after the two-stage crosslinking process. Extensibility of the nanofiber mat reduced after the crosslinking process. However, both aqueous stability and cell attachment improved after the postspinning modifications, as shown through degradation tests in phosphate buffered saline solutions and fibroblast cell culture studies, respectively.

Kynurenine Modulates MMP‐1 and Type‐I Collagen Expression Via Aryl Hydrocarbon Receptor Activation in Dermal Fibroblasts

Dermal fibrosis is characterized by a high deposition of extracellular matrix (ECM) and tissue cellularity. Unfortunately all means of treating this condition are unsatisfactory. We have previously reported the anti‐fibrotic effects of Kynurenine (Kyn), a tryptophan metabolite, in fibrotic rabbit ear model. Here, we report the mechanism by which Kyn modulates the expression of key ECM components in dermal fibroblasts. The results showed that Kyn activates aryl hydrocarbon receptor (AHR) nuclear translocation and up‐regulates cytochrome‐P450 (CYP1A‐1) expression, the AHR target gene. A specific AHR antagonist, 6,2′,4′‐trimethoxyflavone, inhibited the Kyn‐dependent modulation of CYP1A‐1, MMP‐1, and type‐I collagen expression. Establishing the anti‐fibrogenic effect of Kyn and its mechanism of action, we then developed nano‐fibrous Kyn slow‐releasing dressings and examined their anti‐fibrotic efficacy in vitro and in a rat model. Our results showed the feasibility of incorporating Kyn into PVA/PLGA nanofibers, prolonging the Kyn release up to 4 days tested. Application of medicated‐dressings significantly improved the dermal fibrosis indicated by MMP‐1 induction, alpha‐smooth muscle actin and type‐I collagen suppression, and reduced tissue cellularity, T‐cells and myofibroblasts. This study clarifies the mechanism by which Kyn modulates ECM expression and reports the development of a new slow‐releasing anti‐fibrogenic dressing. J. Cell. Physiol. 231: 2749–2760, 2016.

The translational importance of establishing biomarkers of human spinal cord injury

The evaluation of such novel therapies for acute spinal cord injury in clinical trials is extremely challenging. Our current dependence upon the clinical assessment of neurologic impairment renders many acute SCI patients ineligible for trials because they are not examinable. Furthermore, the difficulty in predicting neurologic recovery based on the early clinical assessment forces investigators to recruit large cohorts to have sufficient power. Biomarkers that objectively classify injury severity and better predict neurologic outcome would be valuable tools for translational research. As such, the objective of the present review was to describe some of the translational challenges in acute spinal cord injury research and examine the potential utility of neurochemical biomarkers found within cerebrospinal fluid and blood. We focus on published efforts to establish biological markers for accurately classifying injury severity and precisely predict neurological outcome.

Effects of kynurenine on CD3+ and macrophages in wound healing

As prolongation of the inflammation phase in a healing process frequently leads to wound impairment, here we queried whether kynurenine (Kyn) could modulate this phase of wound healing. To address this, a protein microarray, quantitative polymerase chain reaction (qPCR), flow cytometry for immune cells and immune cell proliferation in the presence and absence of Kyn were conducted and compared. The result of a protein microarray revealed that the expression of 12 pro‐inflammatory cytokines and chemokines was modulated in Kyn‐treated mouse splenocytes as compared with those of control. These findings were then evaluated by conducting a qPCR for the gene expression of these factors and showed a significant reduction in the gene expression of majority of these cytokines and chemokines (interleukin [IL]‐2, IL‐17, C‐X‐C motif chemokine ligand [CXCL] 10, CXCL1, C‐C motif ligand [CCL] 12, CXCL9, CCL4, CXCL2, and CCL5) in response to Kyn treatment. To test the anti‐inflammatory effect of Kyn in an animal model, dorsal surface wounds were generated in a mouse model and wounds received daily topical application of either nothing (control), dermal cream (second control), or Kyn cream using uninjured skin tissue as another control. The wounded tissues were harvested on days 3, 6, and 10 postwounding. As anticipated, the results of fluorescence‐activated cell sorting analysis revealed that upon wounding, the number of total infiltrated CD3+ cells and macrophages (CD11b+) significantly increased on day 3, peaked on day 6, and reduced on day 10 post‐wounding. Interestingly, as compared with those of uninjured and dermal cream alone‐treated wounds, Kyn treatment significantly reduced the number of infiltrated CD3+ cells, but not CD11b+ cells, at different time intervals examined. These findings collectively suggest that Kyn, as a small molecule, can potentially be used to overcome the difficulties associated with persistency of inflammation in healing wounds.

IDO‐Expressing Fibroblasts Protect Islet Beta Cells From Immunological Attack and Reverse Hyperglycemia in Non‐Obese Diabetic Mice

Indoleamine 2,3‐dioxygenase (IDO) induces immunological tolerance in physiological and pathological conditions. Therefore, we used dermal fibroblasts with stable IDO expression as a cell therapy to: (i) Investigate the factors determining the efficacy of this cell therapy for autoimmune diabetes in non‐obese diabetic (NOD) mice; (ii) Scrutinize the potential immunological mechanisms. Newly diabetic NOD mice were randomly injected with either 10 × 106 (10M) or 15 × 106 (15M) IDO‐expressing dermal fibroblasts. Blood glucose levels (BGLs), body weight, plasma kynurenine levels, insulitis severity, islet beta cell function, autoreactive CD8+ T cells, Th17 cells and regulatory T cells (Tregs) were then investigated in these mice. IL‐1β and cleaved caspase‐3 levels were assessed in islets co‐cultured with IDO‐expressing fibroblasts. BGLs in 83% mice treated with 15M IDO‐expressing fibroblasts recovered to normal up to 120 days. However, only 17% mice treated with 10M IDO‐expressing cells were reversed to normoglycemia. A 15M IDO‐expressing fibroblasts significantly reduced infiltrated immune cells in islets and recovered the functionality of remaining islet beta cells in NOD mice. Additionally, they successfully inhibited autoreactive CD8+ T cells and Th17 cells as well as increased Tregs in different organs of NOD mice. Islet beta cells co‐cultured with IDO‐expressing fibroblasts had reduced IL‐1β levels and cell apoptosis. Both cell number and IDO enzymatic activity contributes to the efficiency of IDO cell therapy. Optimized IDO‐expressing fibroblasts successfully reverse the progression of diabetes in NOD mice through induction of Tregs as well as inhibition of beta cell specific autoreactive CD8+ T cells and Th17 cells. J. Cell. Physiol. 231: 1964–1973, 2016.

Identification of a hematopoietic cell dedifferentiation‐inducing factor

It has long been realized that hematopoietic cells may have the capacity to trans‐differentiate into non‐lymphohematopoietic cells under specific conditions. However, the mechanisms and the factors for hematopoietic cell trans‐differentiation remain unknown. In an in vitro culture system, we found that using a conditioned medium from proliferating fibroblasts can induce a subset of hematopoietic cells to become adherent fibroblast‐like cells (FLCs). FLCs are not fibroblasts nor other mesenchymal stromal cells, based on their expression of type‐1 collagen, and other stromal cell marker genes. To identify the active factors in the conditioned medium, we cultured fibroblasts in a serum‐free medium and collected it for further purification. Using the fractions from filter devices of different molecular weight cut‐offs, and ammonium sulfate precipitation collected from the medium, we found the active fraction is a protein. We then purified this fraction by using fast protein liquid chromatography (FPLC) and identified it by mass spectrometer as macrophage colony‐stimulating factor (M‐CSF). The mechanisms of M‐CSF‐inducing trans‐differentiation of hematopoietic cells seem to involve a tyrosine kinase signalling pathway and its known receptor. The FLCs express a number of stem cell markers including SSEA‐1 and ‐3, OCT3/4, NANOG, and SOX2. Spontaneous and induced differentiation experiments confirmed that FLCs can be further differentiated into cell types of three germ layers. These data indicate that hematopoietic cells can be induced by M‐CSF to dedifferentiate to multipotent stem cells. This study also provides a simple method to generate multipotent stem cells for clinical applications. J. Cell. Physiol. 231: 1350–1363, 2016.

Fibroblast Cell-Based Therapy for Experimental Autoimmune Diabetes.

Type 1 diabetes (T1D) results from autoimmune destruction of insulin producing β cells of the pancreatic islets. Curbing autoimmunity at the initiation of T1D can result in recovery of residual β cells and consequently remission of diabetes. Here we report a cell-based therapy for autoimmune diabetes in non-obese diabetic (NOD) mice using dermal fibroblasts. This was achieved by a single injection of fibroblasts, expressing the immunoregulatory molecule indoleamine 2,3 dioxygenase (IDO), into peritoneal cavity of NOD mice shortly after the onset of overt hyperglycemia. Mice were then monitored for reversal of hyperglycemia and changes in inflammatory / regulatory T cell profiles. Blood glucose levels dropped into the normal range in 82% of NOD mice after receiving IDO-expressing fibroblasts while all control mice remained diabetic. We found significantly reduced islet inflammation, increased regulatory T cells, and decreased T helper 17 cells and β cell specific autoreactive CD8+ T cells following IDO cell therapy. We further showed that some of intraperitoneal injected fibroblasts migrated to local lymph nodes and expressed co-inhibitory molecules. These findings suggest that IDO fibroblasts therapy can reinstate self-tolerance and alleviate β cell autoreactivity in NOD mice, resulting in remission of autoimmune diabetes.

IDO expressing fibroblasts suppress the development of imiquimod-induced psoriasis-like dermatitis

Psoriasis is a chronic skin condition whose pathogenesis is reported to be due to the activation of the interleukin-23/interleukin-17 (IL-23/IL-17) pathway. Here, we report that indoleamine 2,3-dioxygenase (IDO)-expressing fibroblasts reduce the activity of this pathway in activated immune cells. The findings showed that intralesional injection of IDO-expressing fibroblasts in imiquimod-induced psoriasis-like dermatitis on the back and ear (Pso. ear group) in mice significantly improves the clinical lesional appearance by reducing the number of skin-infiltrated IL-17+ CD4+ T cells (1.9% ± 0.3% vs. 6.9% ± 0.6%, n = 3, P value < 0.01), IL-17+ γδ+ T cells (2.8% ± 0.3% vs. 11.6% ± 1.2%, n = 3, P value < 0.01), IL-23+ activated dendritic cells (7.6% ± 0.9% vs. 14.0% ± 0.5%, n = 3, P < 0.01), macrophages (4.3% ± 0.1% vs. 11.3% ± 1.0%, n = 3, P value < 0.01), and granulocytes (2.5% ± 0.4% vs. 4.5% ± 0.3%, n = 3, P value < 0.01) as compared to untreated psoriatic mice. This finding suggests that IDO-expressing fibroblasts, and to a lesser extent, non-IDO primary fibroblasts suppress the psoriatic-like symptoms by inhibiting the infiltration of key immune cells involved in the development of psoriasis.