Islet neogenesis from the constitutively nestin expressing human umbilical cord matrix derived mesenchymal stem cells.

The scarcity of islets for transplantation calls for an alternative sources of islets. The human umbilical cord has been shown to be a reservoir of multipotent stem cells with capacity to differentiate into ectodermal, mesodermal and endodermal lineages. The present investigation deals with isolation and characterization of mesenchymal stem sells (MSC) derived from human umbilical cord and their differentiation into functional islets. Since these MSCs were found to constitutively express nestin we hypothesized that these would be ideal candidates for islet neogenesis without any further manipulation. Human umbilical cord matrix stem cells (hUCMSCs) were found to express CD29, CD44, CD73, CD90, CD105, smooth muscle actin, nestin, vimentin, proliferation marker Ki67 and embryonic markers Oct4, SSEA4. These were found to be negative for CD33, CD34, CD45 and HLA DR. Human UCMSCs exhibited high proliferating capacity for extended period indicating potential for scaling up. When subjected to a cocktail of specific differentiating factors, these cells differentiated into fat, cartilage, bone, neurons and islet like clusters (ILCs). These ILCs stained positive for diphenylthiocarbazone (DTZ) and expressed human C-peptide, insulin and glucagon. Real time qPCR analysis of newly generated islets further demonstrated abundance of Pdx-1, Ngn3, insulin, glucagon and somatostatin transcripts. On transplantation in experimental diabetic mice these ILCs restored normoglycemia, body weight and exhibited normal glucose tolerance test indicating their functional status. Thus, the present study demonstrates potential of constitutively expressing nestin positive progenitor from umbilical cord as a novel source for islet neogenesis and their usage in cell replacement therapy for diabetes.