HUMAN ISLET PURIFICATION - A PROSPECTIVE COMPARISON OF EURO-FICOLL AND BOVINE SERUM-ALBUMIN DENSITY GRADIENTS

Euro-Ficoll (EF) and bovine serum albumin (BSA) are the two most commo nly used media for the density gradient purification of human pancreat ic islets. The aim of this study was to compare these two media with r espect to the efficiency of human islet isolation. Ten human pancreata were collagenase-digested, and samples of digest were separated on ei ther a continuous linear density gradient of BSA or a discontinuous gr adient of EF (1.108/1.096/1.037/Euro-Collins). Efficiency of islet pur ification was assessed by insulin and amylase assay of aliquots aspira ted from the BSA gradients, and from the interfaces of the EF gradient s. Islets were obtained from two interfaces in the EF gradients. Islet yield from the upper interface was generally poor (median 28% of tota l insulin; range 2-71%), but purity was better than for an equivalent yield using BSA [1% (0-3%) amylase contamination for EF versus 6% (0-3 7%) for BSA; P=0.013]. Pooling both EF interfaces increased yield to 6 6% (17-81%) but markedly reduced purity [46% (0-50%) amylase for EF ve rsus 31% (0-52%) for BSA]. In conclusion, the efficiency of human isle t purification is similar, though disappointingly low, with BSA and wi th EF. Considerable scope exists, therefore, for improvement in the de nsity gradient purification of human islets.