Culture and function of electrofusion-derived clonal insulin-secreting cells immobilized on solid and macroporous microcarrier beads

In view of the advantages of the bulk production of clonal pancreatic beta cells, an investigation was made of the growth and insulin secretory functions of an electrofusion-derived cell line (BRIN-BD11) immobilized on a solid microcarrier, cytodex-1 or a macroporous microcarrier, cultispher-G. For comparison, similar tests were performed using BRIN-BD11 cells present in single cell suspensions or allowed to form pseudoislets. Similar growth profiles were recorded for each microcarrier with densities of 4.4 x 10⁵ ± 0.3 cells/ml and 4.2 x 10⁵ ± 0.2 cells/ml achieved using cytodex-1 and cultispher-G, respectively. Cell viability began to decline on day 5 of culture. Insulin concentration in the culture medium reached a peak of 26 ± 2.0 ng/ml and 24 ± 2.2 ng/ml for cells grown on cytodex-1 and cultispher-G, respectively. Cells grown on both types of microcarrier showed a significant 1.5-1.8-fold acute insulin-secretory response to 16.7 mmol/l glucose. L-alanine (10 mmol/l) and L-arginine (10 mmol/l) also induced significant 3-4 fold increases of insulin release. BRIN-BD11 cells immobilized on cytodex-1 or cultispher-G out-performed single cell suspensions and pseudoislets in terms of insulin-secretory responses to glucose and amino acids. A 1.3-fold, 2.2-fold and 1.7-fold stimulation of insulin secretion was observed for glucose, L-alanine and L-arginine respectively in single cell suspensions. Corresponding increases for pseudoislets were 1.6-1.8-fold for L-alanine and L-arginine, with no significant response to glucose alone. These data indicate the utility of micro-carriers for the production of functioning clonal beta cells.