A low frequency of pancreatic islet insulin-expressing cells derived from cord blood stem cell allografts in humans

Aims/hypothesis: We sought to establish if stem cells contained in cord blood cell allografts have the capacity to differentiate into insulin-expressing beta cells in humans. Methods: We studied pancreases obtained at autopsy from individuals (n=11) who had prior opposite-sex cord blood transplants to reconstitute haematopoiesis. Pancreatic tissue sections were stained first by XY-fluorescence in situ hybridisation and then insulin immunohistochemistry. Pancreases obtained at autopsy from participants without cord blood cell infusions served as controls (n=11). Results: In the men with prior transplant of female cord blood, there were 3.4±0.3% XX-positive insulin-expressing islet cells compared with 0.32±0.05% (p<0.01) in male controls. In women with prior transplant of male cord blood cells we detected 1.03±0.20% XY insulin-expressing islet cells compared with 0.03±0.03 in female controls (p<0. 001). Conclusions/interpretation: Cord blood stem cells have the capacity to differentiate into insulin-expressing cells in non-diabetic humans. It remains to be established whether these cells have the properties of beta cells.