Size-controlled insulin-secreting cell clusters

The search for an effective cure for type I diabetes from the transplantation of encapsulated pancreatic beta-cell clusters has so far produced sub-optimal clinical outcomes. Previous efforts have not controlled the size of transplanted clusters, a parameter implicated in affecting long-term viability and the secretion of therapeutically sufficient insulin. Here we demonstrate a method based on covalent attachment of patterned laminin for fabricating uniformly size-controlled insulin-secreting cell clusters. We show that cluster size within the range 40-120 mu m in diameter affects a variety of therapeutically relevant cellular responses including insulin expression, content and secretion. Our studies elucidate two size-dependent phenomena: (1) as the cluster size increases from 40 mu m to 60 mu m, glucose stimulation results in a greater amount of insulin produced per cell; and (2) as the cluster size increases beyond 60 mu m, sustained glucose stimulation results in a greater amount of insulin secreted per cell. Our study describes a method for producing uniformly sized insulin-secreting cell clusters, and since larger cluster sizes risk nutrient availability limitations, our data suggest that 100-120 mu m clusters may provide optimal viability and efficacy for encapsulated beta-cell transplants as a treatment for type I diabetes and that further in vivo evaluation is warranted. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.