The therapeutic efficacy of adipose stromal cells in a model of multiple sclerosis
Description
Multiple sclerosis (MS) is a common neurodegenerative disease and remains an unmet clinical challenge. In MS, an autoimmune response leads to immune cell infiltration, inflammation, demyelination, and lesions in central nervous system (CNS) tissues resulting in tremors, fatigue, and progressive loss of motor function. These pathologic hallmarks are effectively reproduced in the murine experimental autoimmune encephalomyelitis (EAE) model. Using the EAE mouse, we have defined critical time points during the disease progression that have correlative immunopathology with those that occur in MS. As promising therapeutic alternatives to treat MS, we investigated the fresh, heterogeneous population of cells from adipose called the stromal vascular fraction (SVF), which contains adipose-derived stromal/stem cells (ASCs). With these studies, we evaluated the therapeutic efficacies of fresh SVF cells and culture-expanded ASCs at early and late stage EAE disease after intraperitoneal (i.p.) administration. At early stage EAE disease, autoimmune reactions and inflammation are prevalent in the periphery lead to CNS damage by the infiltration of cells that generate inflammatory and demyelinating lesions. We demonstrated that at this time, treatment with SVF cells and ASCs were incapable of attenuating CNS pathology. However, the potency of SVF cells to suppress the autoimmune reactions in the periphery was strong enough to partially ameliorate motor impairments. Furthermore, we revealed the altered gene expressions of the SVF cells and ASCs when exposed to this pathogenic milieu in vitro. Not only did we show that the majority of the helper T (TH) cells contained within the SVF are of the TH2 phenotype, but the most enhanced cytokines in response to the inflammatory milieu were interleukin-10 (IL-10) and transforming growth factor-β (TGFβ) which promote regulatory T cells (Tregs). The most dominant increase detected in ASCs was interleukin-6 (IL-6) which correlates with the inability of ASCs to suppress the activities of the pathogenic T cells at early stage disease. At late stage disease, we showed the greatest improvements in SVF-treated EAE mice that led to amelioration to pathology in CNS tissues and partial restoration of motor function. The most pronounced changes following SVF treatment were the high levels of IL-10 in the peripheral blood, lymphoid and CNS tissues along with the induction of regulatory T cells in the lymph nodes which indicated potent immunomodulatory effects. These effects were not as robust following ASC treatment. A deeper investigation into the potential mechanisms showed phenotypes of T cells and macrophages skewed towards favorable phenotypes. SVF treatment shifted the TH cell subsets away from the effector TH1 and TH2 and toward the Tregs which promote immune tolerance and anti-inflammatory effects. Furthermore, the Treg-associated effects involve the induction of the alternative activation phenotype of macrophages, or M2, which were evidenced in the spleens and CNS tissues of SVF-treated EAE mice. Moreover, we determined that i.p. injected ASCs, and more so, SVF cells were still present in the spleens of EAE mice after 5 days. Together, we investigated a novel modality for treating an inflammatory, autoimmune disease. By comparison with ASC treatment, we demonstrated potential mechanisms of SVF treatment at early and late stage EAE disease that are translational to the inflammatory and demyelinating phases MS disease, respectively. We determined that the timing of administration is most critical, and once active immune activities subside, SVF treatment provides robust and comprehensive effects for improving CNS damage. Additionally, these mechanisms may translate and help explain the favorable effects with current clinical applications such as cell-assisted liposuction that uses SVF cells for improving fat grafting yet mechanisms are still unclear.