Optimization of islet transfection protocol. (A) Intact islets transfected with DOTAP at a DNA/liposome ratio of 1:6 (V/V). Transfected cells within the islets appear green. (B) Glucose stimulated insulin release in control (open squares, n = 6) and DOTAP-treated islets (closed squares, n = 4). Insulin secretion (as % of total islet content) was measured in response to different concentrations of glucose. DOTAP did not modify insulin secretion.