A Comparison Between Islet And Stem Cell Transplantation For Treatment Of Type 1 Diabetes Mellitus: A Systematic Review

Abstract

Introduction: The incidence of type 1 Diabetes Mellitus (T1DM) has been increasing rapidly worldwide in the past decade. The current standard treatment is exogenous insulin therapy, however, this procedure is highly associated with poor glycemic control that may lead to life-threatening hypoglycemic episodes. Cellular-based therapy for T1DM has been recently developed, making it pertinent to compare the effectiveness between two most anticipated breakthroughs: islet cell and stem cell transplantation, in order to determine which procedure is more effective. Methods: A comprehensive digital literature search was performed using PubMed and Ovid Medline for primary research studies published between Jan 2000 – Nov 2015. Relevant cohort, case-control, case series, and in vivo studies were included. The abstracts and full text of the retrieved articles were scanned for potential studies that fulfilled the inclusion criterias. The quality assessment of studies were conducted using ARRIVE, NOS, and MINORS. Results: Nineteen primary research studies met the inclusion criterias and were assessed for the review. Eleven out of 19, were considered as high-quality, while the rest were moderate-quality. The studies generally reported the insulin independence, graft functionality, and glycemic control. The insulin-independent period for islet cell tranplantation was proven to be longer compared to stem cell transplantation with better glycemic control. Stem cells were successfully differentiated into glucoseresponsive insulin-producing cells, that also released glucagon and somatostatin. Discussion: The majority of the included studies were using the same outcome measures which allow a more comprehensive comparison to be conducted. Based on the assessment, islet cell transplantation is currently better. This treatment was found to lead to significant improvements in insulin independence and glycemic control observed through insulin-free period, HbA1c, blood glucose, and C-peptide serum measurement. On the other hand, certain challenges – such as donor shortage and poor engraftment - hinders the widespread application of the treatment. Therefore, stem cell transplantation is thought to possibly be replacing islet cell transplantation in the future. Stem cells had successfully been differentiated into β-like cells that were not only producing insulin, but also glucagon and somatostatin, as well as acting in glucose-stimulated manner, imitating the physiologic mechanism of β-cells. Conclusion: It is conclusive that islet stem cell transplantation was proven to perform relatively better in terms of insulin independence and glycemic control compared to stem cell transplantation for treating T1DM. Both cellular-based treatments provided relatively better glycemic control compared to the current standard treatment, exogenous insulin therapy. All the studies have reported that both treatments lead to substantial improveent between pre-and post-transplantation periods. Stem cell transplantation was also proven to have unlimited potentials to be the future solution for T1DM. Although, there was limited studies on human subjects, but based on the current available studies, the results were quite conclusive.