Human Mesenchymal Stem Cells (hMSCs) are the non-hematopoietic, multipotent stem cells with the capacity to differentiate into mesodermal lineages such as osteocytes, adipocytes, and chondrocytes as well ectodermal (neurocytes) and endodermal lineages (hepatocytes).
Until recently, when the immunomodulation properties of MSCs were proven to be clinically relevant, the use of these stem cells was met with skepticism and doubt by a large portion of the scientific community.
However, since that time, MSCs have demonstrated tremendous potential for allogeneic use in a number of applications, including cell replacement, and tissue regeneration, and for use in the therapeutic treatment of immune- and inflammation-mediated diseases. In fact, in many cases, the use of MSCs has been so successful that they appear to demonstrate more efficacy than what has been observed previously in traditional regenerative medicine.
Among the many benefits making MSCs so interesting for this application is their capacity for both multilineage differentiation and immunomodulation. Obtaining a better understanding of these capacities has opened new doors in regenerative medicine and demonstrated that these somatic progenitor cells are highly versatile for a wide range of therapeutic applications.
Additionally, the authors of this review point to research indicating the capacity of MSCs to home to the site of injury and/or inflammation, making them more attractive for use in clinical application. In this review, Wang et al. focus on this non-traditional clinical use of tissue-specific stem cells and highlight important findings and trends in this exciting area of stem cell therapy.
At the time this review was published, there were over 500 MSCs-related studies registered with the NIH Clinical Trial Database. Interestingly, nearly half of these trials involve attempts to better understand the use of MSCs in treating immune- and inflammation-mediated diseases – an indication of the recent shift in focus when determining effective therapeutic applications of MSCs.
In reviewing these clinical trials, Wang et al. found that the most common immune-/inflammation-mediated indications in MSC clinical trials were for graft-versus-host disease (GVHD), osteoarthritis (OA), obstructive airway disease, multiple sclerosis (MS), and solid organ transplant rejection.
Clinical trials involving MSCs, and specifically HSCs, in GVHD have indicated that while there may be indications of immunosuppressant therapy, immune rejection in the form of GVHD is still a major cause of morbidity and mortality, occurring in 30 ~ 40 % of allogeneic HSC transplantations.
Despite a number of clinical trials indicating significant efficacy in the use of MSCs for GVHD treatment, the authors point out that these findings were not observed consistently throughout all trials. Significant differences in these studies appeared to be related to differences in adult and pediatric applications, a specific type of HSC that was transplanted, and the type of MSCs that were utilized. There also appears to be a disparity in the results obtained from similar studies conducted in Europe and North America. Considering this, there are a number of studies involving MSCs and GVHD still ongoing.
These findings led the authors to conclude that despite the strong potential of MSCs as therapeutic agents for GVHD, detailed tailoring of the patient population and stringent MSC processing criteria are necessary to deliver consistent and reproducible results.
Despite the mixed findings for use of MSCs in the treatment of GVHD, trials reviewed for other immune/inflammation-mediated diseases, including MS, inflammatory bowel disease, OA, RA, and inflammatory airway and pulmonary diseases demonstrated positive results pertaining to the safety of MSC therapy when used in this application.
Specifically, Wang et al. point out that although there have been positive results observed in preclinical animal studies, these results have not translated to clinical efficacy. In considering this, the authors suggest a focus on better clarifying pathophysiological details and subsets within disease entities to better tailor MSC therapy and standardization of in vitro culture protocols with stringent criteria for testing of functional parameters as two important steps to improve our understanding on the mechanistic properties of MSC immunomodulation.
Despite these recommendations, the authors conclude that the current results and developments of these clinical trials demonstrate that the tremendous potential of MSC therapy in a wide range of areas, including the treatment of immune/inflammation-mediated diseases, can be expected in the near future to achieve clinical relevance.
Source: “Human mesenchymal stem cells (MSCs) for treatment towards ….” 4 Nov. 2016, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5095977/.