Hydraulic conductivity (Lp) and its activation energy (Ea), cryoprotectant agent permeability (Ps) and its Ea, and reflection coefficients (σ) for golden hamster individual pancreatic islet cell membranes

Long-term cryopreservation of' islets of Langerhans would be advantageous to a clinical islet transplantation program, Fundamental cryobiology utilizes knowledge of basic biophysical characteristics to increase the understanding of the preservation process and possibly increase survival rate. In this study several of these previously unreported characteristics have been determined fbr individual islet cells isolated from Golden hamster islets. Using an electronic particle counting device and a temperature control apparatus, dynamic volumetric response of individual islet cells to anisosmotic challenges of' 1.5 M dimethyl sulfoxide (DMSO) and 1.5 M ethylene glycol (EG) were recorded at four temperatures (8, 22, 28, and 37 degrees C), The resulting curves were fitted using Kedem and Katchalsky equations which describe watts flux and cryoprotectant agent (CPA) flux based on hydraulic conductivity (L-p), CPA permeability (P-s), and reflection coefficient (sigma) for the membrane. For Golden hamster islet cells. L-p, P-s, and sigma for DMSO at 22 degrees C were found to be 0.23 +/- 0.06 mu m/min/atm, 0.79 +/- 0.32 x 10(-3) cm/min, and 0.55 +/- 0.37 (n = 11) (mean +/- SD), respectively. For EG at 22 degrees C, L-p equaled 0.23 +/- 0.06 mu m/min/atm, P-s equaled 0.63 +/- 0.20 x 10(-3) cm/min, and sigma was 0.75 +/- 0.17 (n = 9). Arrhenius plots (ln L-p or In P-s versus l/temperature (K)) were created by adding the data from the other three temperatures and the resulting linear regression yielded correlation coefficients (r) of 0.99 for all four plots (L-p and P-s for both CPAs). Activation energies (E-a) of L-p and P-s were calculated from the slopes of the regressions. The values for DMSO were found to be 12.43 and 18.34 kcal/mol for L-p and P-s (four temperatures, total n = 52), respectively. For EG. E-a of L-p was 11.69 kcal/mol and E-a of P-s was 20.35 kcal/mol (four temperatures, total n = 58). (C) 1998 Academic Press.