Expansion of human beta cells: is insulin recoverable after monolayer expansion?

FLORES LE; KAYALI AG; LOPEZ AD; KUTLU B; BAETGE E; HAO E; KITAMURA R; BEATTIE GM; HAYEK A

Aspen, Colorado EEUU

Simposio; IV Annual Meeting of the Western Region Islet Study Group (WRISG).; 2006

Western Region Islet Study Group (WRISG).

The limited availability of organs is an obstacle to the widespread use of islet transplantation in type 1 diabetic patients. To address this problem many studies have been performed exploring methods to expand functional human islets in vitro for diabetes cell therapy. We previously showed that islets are able to replicate after monolayer formation under the influence of hepatocyte growth factor (HGF) and selected extracellular matrices. However, under these conditions, after >15 doublings senescence and loss of insulin expression occur. Recently other investigators (Gershengorn MC et al. Science, 306, 2261, 2004) have reported that islet cells expanded in monolayers for at least three months, replicate through a reversible epithelial to mesenchymal transition (EMT). Upon removal of serum from the cultures, islet-like structures are formed with the capability to produce insulin. The aim of the present study was to compare the 2 methods for islet expansion using microarrays, real time qPCR and immunostaining at arrival of the islets to the lab, 3 weeks after monolayer expansion and 5-days after culture in serum-free media. At this time, cell aliquots were grafted into nude mice for further study of in vivo function. Both methods showed similar results in islet cell expansion but in neither did we observe recovery in the capacity of the cells to produce insulin. In addition, preliminary data indicate that there were quantitative differences in the expression of mesodermal and endodermal genes during the expansion phase. Re-differentiation of beta cells in vitro after expansion is still a challenge in need of a solution.