Multipotent adult progenitor cells induce regulatory T cells and promote their suppressive phenotype via TGFβ and monocyte-dependent mechanisms

Dysregulation of the immune system can initiate chronic inflammatory responses that exacerbate disease pathology. Multipotent adult progenitor cells (MAPC cells), an adult adherent bone-marrow derived stromal cell, have been observed to promote the resolution of uncontrolled inflammatory responses in a variety of clinical conditions including acute ischemic stroke, acute myocardial infarction (AMI), graft vs host disease (GvHD), and acute respiratory distress syndrome (ARDS). One of the proposed mechanisms by which MAPC cells modulate immune responses is via the induction of regulatory T cells (Tregs), however, the mechanism(s) involved remains to be fully elucidated. Herein, we demonstrate that, in an in vitro setting, MAPC cells increase Treg frequencies by promoting Treg proliferation and CD4+ T cell differentiation into Tregs. Moreover, MAPC cell-induced Tregs (miTregs) have a more suppressive phenotype characterized by increased expression of CTLA-4, HLA-DR, and PD-L1 and T cell suppression capacity. MAPC cells also promoted Treg activation by inducing CD45RA+ CD45RO+ transitional Tregs. Additionally, we identify transforming growth factor beta (TGFβ) as an essential factor for Treg induction secreted by MAPC cells. Furthermore, inhibition of indoleamine 2, 3-dioxygenase (IDO) resulted in decreased Treg induction by MAPC cells demonstrating IDO involvement. Our studies also show that CD14+ monocytes play a critical role in Treg induction by MAPC cells. Our study describes MAPC cell dependent Treg phenotypic changes and provides evidence of potential mechanisms by which MAPC cells promote Treg differentiation.

Abstract P433: Multipotent Adult Progenitor Cells as a Highly Promising Therapy for Treatment of Intracerebral Hemorrhage

Background: Multipotent adult progenitor cells (MAPC) are an adherent adult stem cell being evaluated as a treatment for ischemic stroke in humans under the name MultiStem®. However, the efficacy of MAPC cells for the treatment of intracerebral hemorrhage (ICH), the most devastating form of stroke for which there is no effective treatment, is not clear Method: The therapeutic efficacy of MAPC administration was evaluated in both autologous blood injection (ABI) and collagenase (COL) rat ICH models. We treated rats intravenously with 1.2x10 6 cells (sub-optimal dose based on MAPC efficacy in ischemic stroke) and 1.2x10 7 cells (optimal dose) at either 2 or 24h after ICH, and used 2 different doses of collagenase to better understand the dose responses. Outcome measurements included 4 sensorimotor tests (up to 28d), ventricular hypertrophy, spleen size, and body weight (N=128 rats tested across 4 separate experiments). Results: MAPC offered a robust benefit in both ICH models in a dose-dependent fashion. (1) ABI model: at the sub-optimal dose MAPCs had no significant effect on behavioral performance, but effectively reduced ventricular hypertrophy. At an optimal dose, MAPCs at 2h or 24h after ICH, robustly reduced deficits in all 4 behavioral tests, and reduced ventricular hypertrophy by 59% and 35% in 2h and 24h post-treatment groups, respectively. No difference in body weight and spleen size was observed. (2) COL model: MAPC administered 2h after high collagenase dose, reduced hematoma volume (hemispheric hemoglobin level), as measured at 48h after collagenase injection. In addition, MAPC administration significantly reduced neurological deficit in the COL model. Conclusions: MAPC provide a uniquely robust therapeutic effect on clinically relevant neurological and morphological outcomes in two different ICH models. MAPC also reduced bleeding in the COL model, suggesting the potential for MAPC as a safe acute therapeutic treatment after ICH. In addition to having beneficial effects on recovery processes, MAPC could be further evaluated as a candidate to limit the hematoma enlargement during the initial postictal period. We are currently investigating the mechanism of MAPC-induced post-ICH recovery as well as hemostasis using tissue microarray analysis.

First person – Lozan Sheriff and Reenam Kahn

ABSTRACTFirst Person is a series of interviews with the first authors of a selection of papers published in Disease Models & Mechanisms, helping early-career researchers promote themselves alongside their papers. Lozan Sheriff and Reenam Kahn are co-first authors on ‘Alcoholic hepatitis and metabolic disturbance in female mice: a more tractable model than Nrf2−/− animals’, published in DMM. Lozan is a postdoctoral research fellow in the lab of Dr Patricia Lalor and Reenam a PhD student in the lab of Prof. Phil Newsome. Both are at the Centre for Liver and Gastrointestinal Research, Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, UK, investigating the potential of multipotent adult progenitor cells (MAPCs) as a novel therapy for alcoholic steatohepatitis.

Multipotent Adult Progenitor Cells induce Regulatory T cells and promote their Suppressive Phenotype via TGFβ and Monocyte-dependent Mechanisms

Background: Dysregulation of the immune system can initiate chronic inflammatory responses that exacerbate disease pathology. Multipotent adult progenitor cells (MAPC® cells), an adult, adherent bone-marrow derived stromal cell, have been observed to promote the resolution of uncontrolled inflammatory responses in a variety of clinical conditions including: acute ischemic stroke, acute myocardial infarction (AMI), graft vs host disease (GvHD), and acute respiratory distress syndrome (ARDS). One of the proposed mechanisms by which MAPC cells modulate immune responses is via the induction of regulatory T cells (Tregs), however, the mechanism(s) involved remains to be fully elucidated. Methods: To examine MAPC cell mediated Treg induction, peripheral mononuclear cells (PBMCs) were co-cultured with MAPC cells at various PBMC: MAPC cell ratios. Treg frequencies and phenotype was determined by flow cytometry. The mechanisms involved in MAPC cell induction of Tregs were assessed using transforming growth factor β (TGF) and indoleamine 2, 3 dioxygenase (IDO) inhibitors. Monocyte involvement in MAPC cell induction of Tregs was also explored.Results: Herein, we demonstrate that, in an in vitro setting, MAPC cells increase Treg frequencies by promoting Treg proliferation and CD4+ T cell differentiation into Tregs. Moreover, MAPC cell-induced Tregs (miTregs) have a more suppressive phenotype characterized by increased expression of CTLA-4, HLA-DR, and PD-L1 and T cell suppression capacity. MAPC cells also promoted Treg activation by inducing CD45RA+ CD45RO+ transitional Tregs. Additionally, we identify TGFβ as an essential factor for Treg induction secreted by MAPC cells. Furthermore, IDO resulted in decreased Treg induction by MAPC cells demonstrating IDO involvement. Our studies also show that CD14+ monocytes play a critical role in Treg induction by MAPC cells. Conclusions Our study describes MAPC cell dependent Treg phenotypic changes and provides evidence of potential mechanisms by which MAPC cells promote Treg differentiation.

Multipotent adult progenitor cells grown under xenobiotic-free conditions support vascularization during wound healing

Background Cell therapy has been evaluated pre-clinically and clinically as a means to improve wound vascularization and healing. While translation of this approach to clinical practice ideally requires the availability of clinical grade xenobiotic-free cell preparations, studies proving the pre-clinical efficacy of the latter are mostly lacking. Here, the potential of xenobiotic-free human multipotent adult progenitor cell (XF-hMAPC®) preparations to promote vascularization was evaluated. Methods The potential of XF-hMAPC cells to support blood vessel formation was first scored in an in vivo Matrigel assay in mice. Next, a dose-response study was performed with XF-hMAPC cells in which they were tested for their ability to support vascularization and (epi) dermal healing in a physiologically relevant splinted wound mouse model. Results XF-hMAPC cells supported blood vessel formation in Matrigel by promoting the formation of mature (smooth muscle cell-coated) vessels. Furthermore, XF-hMAPC cells dose-dependently improved wound vascularization associated with increasing wound closure and re-epithelialization, granulation tissue formation, and dermal collagen organization. Conclusions Here, we demonstrated that the administration of clinical-grade XF-hMAPC cells in mice represents an effective approach for improving wound vascularization and healing that is readily applicable for translation in humans.