BackgroundWe evaluated the therapeutic effect and fate of high doses of human umbilical cord Wharton jelly cells (hUCWJCs) after IP administration to streptozotocin (STZ)-induced diabetic mice.MethodsType 1 diabetes (T1D) was induced in Kunming mice via IP injection of STZ. hUCWJCs were labeled with 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate (DiI). Diabetic animals with sustained hyperglycemia for at least 2 weeks were administered 1 × 107 Dil-hUCWJCs via intraperitoneal injection. Insulin, glucagon and PDX-1 were detected by immunofluorescence with confocal microscopy. Serum mouse and human C-peptide was assayed in blood collected via intracardiac puncture. Specific β-cell differentiation markers and human DNA were assessed using qPCR performed with 200 ng of target DNA.ResultshUCWJCs migrated to the STZ-damaged organs and contributed to lower blood glucose levels in 30% of the treated mice. Confocal microscopy revealed the presence of resident insulin-positive cells in the liver and kidneys. hUCWJC-treated mice with restored hyperglycemia also showed increased serum mouse C-peptide levels. The qPCR results, particularly in the liver, revealed that after transplantation hUCWJCs upregulated genes of endocrine precursors but failed to express endocrine stage markers. Mice with restored hyperglycemia had reduced urinary volume and lacked glomerular hypertrophy, exhibiting a morphology resembling that of normal glomeruli. Moreover, we also verified that one of the possible mechanisms by which hUCWJCs exert immunosuppressive effects is through down-regulation of the cell surface receptor HLA-1.ConclusionsWe confirmed the potential of IP administration of hUCWJCs and the capability of these cells to migrate to damaged tissues and promote insulin secretion from non-pancreatic local cells and to improve renal damage. These findings confer unique therapeutic properties to hUCWJCs, suggesting a promising future in the treatment of diabetes mellitus.