Size-Controlled Islet-Cell Spheroids for Geometric Analysis of Insulin Secretion

We developed a method to prepare size-and shape-controlled islet-cell spheroids. We cultured beta-cell line (MIN6-m9) in PDMS-microwells and enabled to construct their spheroids with the various sizes corresponding to those of the microwells. We demonstrated the geometric analysis of insulin secretion of the cells in the spheroids. We found that these spheroids respond to glucose and subsequently secrete insulin. Also, immunocytochemistry and the real-time live cell imaging of the Ca²⁺ oscillation revealed for the first time that the only cells approximately 36 mum apart from the periphery showed higher insulin secretion in the spheroid. This result indicates that our MEMS technique controlling the size and the shape of the spheroids is useful to construct islet-like tissue that functions efficiently and is applicable to transplantation therapy targeted to insulin dependent diabetes mellitus.