Towards Standardized Stem Cell Therapy in Type 2 Diabetes Mellitus: A Systematic Review.

Objective: To compile and analyze the published studies on cell therapy for type 2 diabetes mellitus (T2DM) to obtain a better insight into management of T2DM that involved stem cell therapy.

Methods: We searched all published studies in Pubmed/Medline, and Cochrane library, using keywords: ‘stem cell’ AND ‘therapy’ AND ‘diabetes type 2’. Inclusion criteria: original articles on the use of stem cells in humans with T2DM. Exclusion criteria: articles in the non-English literature, studies on T2DM complications that did not assess both adverse events and any of the common diabetes study outcomes. Data collection: type of study, number of cases, and all data that were related to outcome and adverse events. Data were analyzed descriptively to conclude the possible cause of adverse reactions, and which protocols gave a satisfactory outcome.

Results: We collected 25 original articles, out of which 17 studies did not have controls and were classified as case reports, while there were 8 studies that were controlled clinical trials. Most studies used autologous bone marrow mononuclear cells (BM-MNCs) or autologous or allogeneic mesenchymal stem cells (MSCs) from various sources. Adverse events were mild and mostly intervention related. Efficacy of autologous BM-MNCs that were given via interventional route was comparable to Wharton jelly or umbilical cord MSCs that were given via intravenous (IV), Intra muscular (IM), or subcutaneous (SC) route.

Conclusion: Further controlled studies that compare BM-MNCs to BM-MSCs or WJ-MSCs or UCSCs are recommended to prove their comparable efficacy. In addition, studies that compare various routes of administration (IV, IM or SC) versus the more invasive interventional routes are needed.