Anoikis, extracellular matrix, and apoptosis factors in isolated cell transplantation

Isolated cell transplantation (ICT) of pancreatic islets (PI), nerve tissue, hepatocytes, and other cells is an exciting new concept of transplantation. PI transplantation can be successful in reversing diabetes but, unlike whole pancreas, grafts have a unique and unexplained high failure rate, with over 60% loss by 3 to 6 months. We established that PI of rhesus monkeys have a high rate of death within 48 hours of isolation as a result of apoptosis, as measured with the Annexin V assay (Pharmingen, San Diego, Calif). In contrast, PI incompletely separated from the extracellular matrix (ECM) remained viable for prolonged periods in culture and performed superiorly in perifusion assays (insulin secretion of 4.6 +/- 0.8 times basal secretion).

We studied the ability of the anti-AP Bcl-2 molecule, known to block anoikis (a mechanism of AP due to cell-ECM separation), to prevent apoptosis of isolated PI.

PI transduced with an adenovirus-Bcl-2 gene complex showed a high viability and a low AP rate in culture versus control rhesus PI.

In summary, PI protected from AP by a surrounding ECM mantle or by Adenovirol Vector (AdV) transduction of the Bcl-2 gene showed superior viability without AP in vitro and in vivo evidence of a preserved insulin secretion response to glucose.