Julien Rossignol

Genetically engineered mesenchymal stem cells reduce behavioral deficits in the YAC 128 mouse model of Huntington's disease

The purpose of this study was to evaluate the therapeutic effects of the transplantation of bone-marrow mesenchymal stem cells (MSCs), genetically engineered to over-express brain-derived neurotrophic factor (BDNF) or nerve growth factor (NGF) on motor deficits and neurodegeneration in YAC 128 transgenic mice. MSCs, harvested from mouse femurs, were genetically engineered to over-express BDNF and/or NGF and these cells, or the vehicle solution, were injected into the striata of four-month old YAC 128 transgenic and wild-type mice. Assessments of motor ability on the rotarod and the severity of clasping were made one day prior to transplantation and once monthly, thereafter, to determine the effects of the transplanted cells on motor function. The mice were sacrificed at 13-months of age for immunohistological examination. All YAC 128 mice receiving transplants had reduced clasping, relative to vehicle-treated YAC 128 mice, while YAC 128 mice that were transplanted with MSCs which were genetically engineered to over-express BDNF, had the longest latencies on the rotarod and the least amount of neuronal loss within the striatum of the YAC 128 mice. These results indicate that intrastriatal transplantation of MSCs that over-express BDNF may create an environment within the striatum that slows neurodegenerative processes and provides behavioral sparing in the YAC 128 mouse model of HD. Further research on the long-term safety and efficacy of this approach is needed before its potential clinical utility can be comprehensively assessed.

Mesenchymal stem cells induce a weak immune response in the rat striatum after allo or xenotransplantation

Mesenchymal stem cells (MSCs) have attracted attention for their potential use in regenerative medicine such as brain transplantation. As MSCs are considered to be hypoimmunogenic, transplanted MSCs should not trigger a strong host inflammatory response. To verify this hypothesis, we studied the brain immune response after transplantation of human or rat MSCs into the rat striatum and MSC fate at days 5, 14, 21 and 63 after transplantation. Flow cytometry analysis indicated that both MSCs express CD90 and human leucocyte antigen (MHC) class I, but no MHC class II molecules. They do not express CD45 or CD34 antigens. However, MSC phenotype varies with passage number. Human MSCs have mRNAs for interleukin (IL)‐6, IL‐8, IL‐12, tumour necrosis factor (TNF)‐α and TGF‐β1, whereas rat MSCs express IL‐6‐, IL‐10‐, IL‐12‐ and TGF‐β1‐mRNAs. The quantification shows higher levels of mRNAs for the anti‐inflammatory molecules IL‐6 and TGF‐β1 than for pro‐inflammatory cytokines IL‐8 and IL‐12; ELISA analysis showed no IL‐12 whereas TGF‐β1 and IL‐6 were detected. Transplant size did not significantly vary between 14 and 63 days after transplantation, indicating an absence of immune rejection of the grafts. Very few mast cells and moderate macrophage and microglial infiltrations, observed at day 5 remained stable until day 63 after transplantation in both rat and human MSC grafts. The observations of very few dendritic cells, T αβ‐cells, and no T γδ‐lymphocytes, all three being associated with Tp rejection in the brain, support the contention that MSCs are hypoimmunogenic. Our results suggest that MSCs are of great interest in regenerative medicine in a (xeno)transplantation setting.

Mesenchymal stem cell transplantation and DMEM administration in a 3NP rat model of Huntington's disease: morphological and behavioral outcomes.

Transplantation of mesenchymal stem cells (MSCs) may offer a viable treatment for Huntingtons disease (HD). We tested the efficacy of MSC transplants to reduce deficits in a 3-nitropropionic acid (3NP) rat model of HD. Five groups of rats (Sham, 3NP, 3NP+vehicle, 3NP+TP(low), 3NP+TP(high)), were given PBS or 3NP intraperitoneally, twice daily for 42 days. On day 28, rats in all groups except Sham and 3NP, received intrastriatal injections of either 200,000 MSCs (TP(low)), 400,000 (TP(high)) MSCs or DMEM (VH, the vehicle for transplantation). MSCs survived 72 days without inducing a strong inflammatory response from the striatum. Behavioral sparing was observed on tests of supported-hindlimb-retraction, unsupported-hindlimb-retraction, visual paw placement and stepping ability for 3NP+TP(low) rats and on the unsupported-hindlimb-retraction and rotarod tasks for 3NP+VH rats. Relative to 3NP controls, all treated groups were protected from 3NP-induced enlargement of the lateral ventricles. In vitro, MSCs expressed transcripts for numerous neurotrophic factors. In vivo, increased striatal labeling in BDNF, collagen type-I and fibronectin (but not GDNF or CNTF) was observed in the brains of MSC-transplanted rats but not in DMEM-treated rats. In addition, none of the transplanted MSCs expressed neural phenotypes. These findings suggest that factors other than neuronal replacement underlie the behavioral sparing observed in 3NP rats after MSC transplantation.

Use of genetically modified mesenchymal stem cells to treat neurodegenerative diseases.

The transplantation of mesenchymal stem cells (MSCs) for treating neurodegenerative disorders has received growing attention recently because these cells are readily available, easily expanded in culture, and when transplanted, survive for relatively long periods of time. Given that such transplants have been shown to be safe in a variety of applications, in addition to recent findings that MSCs have useful immunomodulatory and chemotactic properties, the use of these cells as vehicles for delivering or producing beneficial proteins for therapeutic purposes has been the focus of several labs. In our lab, the use of genetic modified MSCs to release neurotrophic factors for the treatment of neurodegenerative diseases is of particular interest. Specifically, glial cell-derived neurotrophic factor (GDNF), nerve growth factor (NGF), and brain derived neurotrophic factor (BDNF) have been recognized as therapeutic trophic factors for Parkinson’s, Alzheimer’s and Huntington’s diseases, respectively. The aim of this literature review is to provide insights into: (1) the inherent properties of MSCs as a platform for neurotrophic factor delivery; (2) the molecular tools available for genetic manipulation of MSCs; (3) the rationale for utilizing various neurotrophic factors for particular neurodegenerative diseases; and (4) the clinical challenges of utilizing genetically modified MSCs.

Transplants of Adult Mesenchymal and Neural Stem Cells Provide Neuroprotection and Behavioral Sparing in a Transgenic Rat Model of Huntington's Disease

Stem cells have gained significant interest as a potential treatment of neurodegenerative diseases, including Huntingtons disease (HD). One source of these cells is adult neural stem cells (aNSCs), which differentiate easily into neuronal lineages. However, these cells are vulnerable to immune responses following transplantation. Another source is bone‐marrow‐derived mesenchymal stem cells (MSCs), which release neurotrophic factors and anti‐inflammatory cytokines following transplantation, and are less vulnerable to rejection. The goal of this study was to compare the efficacy of transplants of MSCs, aNSCs, or cotransplants of MSCs and aNSCs for reducing deficits in a transgenic rat model of HD. HD rats received intrastriatal transplantations of 400,000 MSCs, aNSCs, or a combination of MSCs/aNSCs, while wild‐type and HD controls were given vehicle. Rats were tested on the rotarod over the course of 20 weeks. The results indicated that transplants of: (a) aNSCs produced a strong immune response and conferred short‐term behavioral benefits; (b) MSCs elicited a relatively weak immune response, and provided a longer term behavioral benefit; and (c) combined MSCs and aNSCs conferred long‐term behavioral benefits and increased survival of the transplanted aNSCs. The finding that cotransplanting MSCs with aNSCs can prolong aNSC survival and provide greater behavioral sparing than when the transplants contains only aNSCs suggests that MSCs are capable of creating a more suitable microenvironment for aNSC survival. This cotransplantation strategy may be useful as a future therapeutic option for treating HD, especially if long‐term survival of differentiated cells proves to be critically important for preserving lasting functional outcomes. Stem Cells 2014;32:500–509

Neurotrophic enhancers as therapy for behavioral deficits in rodent models of Huntington's disease: use of gangliosides, substituted pyrimidines, and mesenchymal stem cells.

The interest in using neurotrophic factors as potential treatments for neurodegenerative disorders, such as Huntingtons disease, has grown in the past decade. A major impediment for the clinical utility of neurotrophic factors is their inability to cross the blood-brain barrier in therapeutically significant amounts. Although several novel mechanisms for delivering exogenous neurotrophins to the brain have been developed, most of them involve invasive procedures or present significant risks. One approach to circumventing these problems is using therapeutic agents that can be administered systemically and have the ability to enhance the activity of neurotrophic factors. This review highlights the use of gangliosides, substituted pyrimidines, and mesenchymal stem cells as neurotrophic enhancers that have significant therapeutic potential while avoiding the pitfalls of delivering exogenous neurotrophic factors through the blood-brain barrier. The review focuses on the potential of these neurotrophic enhancers for treating the behavioral deficits in rodent models of Huntingtons disease.

Distinct roles of Bcl-2 and Bcl-Xl in the apoptosis of human bone marrow mesenchymal stem cells during differentiation.

Background Adult mesenchymal stem cells (MSCs) can be maintained over extended periods of time before activation and differentiation. Little is known about the programs that sustain the survival of these cells. Principal Findings Undifferentiated adult human MSCs (hMSCs) did not undergo apoptosis in response to different cell death inducers. Conversely, the same inducers can readily induce apoptosis when hMSCs are engaged in the early stages of differentiation. The survival of undifferentiated cells is linked to the expression of Bcl-Xl and Bcl-2 in completely opposite ways. Bcl-Xl is expressed at similar levels in undifferentiated and differentiated hMSCs while Bcl-2 is expressed only in differentiated cells. In undifferentiated hMSCs, the down-regulation of Bcl-Xl is associated with an increased sensitivity to apoptosis while the ectopic expression of Bcl-2 induced apoptosis. This apoptosis is linked to the presence of cytoplasmic Nur 77 in undifferentiated hMSCs. Significance In hMSCs, the expression of Bcl-2 depends on cellular differentiation and can be either pro- or anti-apoptotic. Bcl-Xl, on the other hand, exhibits an anti-apoptotic activity under all conditions.

Efficacy of Azacitidine in autoimmune and inflammatory disorders associated with myelodysplastic syndromes and chronic myelomonocytic leukemia

This retrospective study describes efficacy of Azacitidine on autoimmune disorders (AID) associated with MDS/CMML in 22 patients. Response of AID to Azacitidine was observed in 19 patients (86%). Reduction or discontinuation of steroids and/or immunosuppressive therapy (IST) was possible in 16 cases (73%). Hematologic response was seen in 55% of the patients. MDS/CMML and AID evolution was concordant in 13 cases (59%): both favorable (n=11), both unfavorable (n=2), but AID improved while MDS/CMML worsened (n=8) and vice versa (n=1). Azacitidine frequently seems effective in controlling steroid-dependent AID associated with MDS/CMML, but prospective studies are necessary to confirm those findings.

Rituximab–cyclophosphamide–dexamethasone combination in management of autoimmune cytopenias associated with chronic lymphocytic leukemia

Abstract We report our experience on rituximab–cyclophosphamide–dexamethasone (RCD) combination therapy for the treatment of autoimmune disorders in 48 patients with chronic lymphocytic leukemia (CLL). The diagnosis of autoimmune disease (AID) was autoimmune hemolytic anemia (AIHA) in 26 (54%), autoimmune thrombocytopenic purpura (AITP) in nine (18.8%), Evans syndrome in eight (16.7%), and pure red cell anemia (PRCA) in five patients (10.5%). CLL was considered progressive in 40% of subjects upon AID diagnosis. Overall, an 89.5% response rate was obtained with this combination, irrespective of the AID type. Relapse occurred in 19 patients (39.6%). The median duration of autoimmunity was 24 months, but the duration of response of autoimmunity (DR-AI) was higher for patients presenting with: (1) AID early during the CLL course (<3 years), or (2) both and pure red cell aplasia (PRCA) in five patients (10.5%) and AIHA.

New lines of GFP transgenic rats relevant for regenerative medicine and gene therapy

Adoptive cell transfer studies in regenerative research and identification of genetically modified cells after gene therapy in vivo require unequivocally identifying and tracking the donor cells in the host tissues, ideally over several days or for up to several months. The use of reporter genes allows identifying the transferred cells but unfortunately most are immunogenic to wild-type hosts and thus trigger rejection in few days. The availability of transgenic animals from the same strain that would express either high levels of the transgene to identify the cells or low levels but that would be tolerant to the transgene would allow performing long-term analysis of labelled cells. Herein, using lentiviral vectors we develop two new lines of GFP-expressing transgenic rats displaying different levels and patterns of GFP-expression. The “high-expresser” line (GFPhigh) displayed high expression in most tissues, including adult neurons and neural precursors, mesenchymal stem cells and in all leukocytes subtypes analysed, including myeloid and plasmacytoid dendritic cells, cells that have not or only poorly characterized in previous GFP-transgenic rats. These GFPhigh-transgenic rats could be useful for transplantation and immunological studies using GFP-positive cells/tissue. The “low-expresser” line expressed very low levels of GFP only in the liver and in less than 5% of lymphoid cells. We demonstrate these animals did not develop detectable humoral and cellular immune responses against both transferred GFP-positive splenocytes and lentivirus-mediated GFP gene transfer. Thus, these GFP-transgenic rats represent useful tools for regenerative medicine and gene therapy.