Autoimmune diseases affect approximately one in twenty people and significantly impact both morbidity and mortality. While some can be managed with non-steroidal anti-inflammatory medications, corticosteroids, immunoglobulin replacement, or, in the case of diabetes, insulin therapy, there is currently no cure for autoimmune disease and no available treatment is without drawbacks. Recent research efforts have tested mesenchymal stroma or stem cells (MSCs) as a possible treatment for a range of autoimmune diseases including multiple sclerosis, Crohn’s disease and diabetes. Although the results are promising, the rarity of MSCs and the large number required for effective treatment mean they must be extensively expanded ex vivo. During this expansion may undergo undesirable changes such as the loss of their multipotency. Moreoever, these cells must be cultured in foetal bovine serum, which can vary significantly from batch to batch and for which there is no adequate substitute.
In a recent study published in Stem Cell Research & Therapy, Bruce Bunnell from Tullane University School of Medicine, USA, and colleagues compare the ability of several sources of human stem cells to inhibit experimental autoimmune encephalomyelitis in mice – an experimental model of chronic multiple schlerosis (MS). They investigated bone marrow derived stromal cells (BMSCs), adipose stem cells (ASCs) and the stromal vascular fraction (SVF) of adipose tissue, all of which like MSCs can differentiate into multiple cell lineages and modulate immune responses. While BMSCs are the most commonly used of this type of cell in studies of autoimmune suppression, they are difficult to obtain in large numbers, and the procedure is painful. Adipose stem cells are easier to obtain but still require ex vivo expansion. SVF cells, by contrast, can be obtained in large numbers with ease and may not require ex vivo expansion to generate sufficient numbers for therapeutic purposes.
Bunnell and colleagues used the mouse model of myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalitis (EAE) to test whether intra-peritoneal injection of BMSCs, ASCs, or SVF at the time of disease induction could prevent the onset or reduce the severity of disease. While all three treatments significantly reduced all measures of disease, the ASCs and SVF were also able to prevent disease altogether in 25 and 17 percent of animals, respectively. Levels of IFN-γ and IL-12, two cytokines implicated in autoimmune modulation, were also measured. The levels of both were reduced by all three treatments, but the level of IL-12 was significantly lower in animals treated with SVF than those treated with either BMSCs or ASCs.
These results indicate that SVF may be an effective alternative to BMSCs in treating autoimmune diseases; one which is both easier to obtain and subject to less potential variability caused by ex vivo expansion. However larger sample sizes are needed to consolidate these findings. Furthermore, it will be interesting to determine whether delivery of SVF after disease onset, rather than at the time of disease induction, can likewise reduce the severity of symptoms if this is to be used as a treatment.