CRYOPRESERVATION ELIMINATES GAL??1-3GAL AND THOMSEN - FREIDENREICH (T F) EXPRESSION ON ADULT PORCINE PANCREATIC ISLETS

Abstract

281 The modification of xeno-antigen (Galα1-3Gal and T F) expression on porcine islets may facilitate successful pig to human islet xenotransplantation. Purpose: We studied the effect of cryopreservation on altering the expression of Galα1-3Gal and T F antigens on adult porcine pancreatic islets. Methods: Two pancreases from outbred adult White Large pigs were obtained from an abattoir. Islet isolation was performed by the Ricordi semi-automated method. The unpurified islet preparation were washed in HBSS and 50% of the islets were fixed in formalin. The rest of the islets were cryopreserved: after suspension in RPMI-60 at 4° C, DMSO was added stepwise to a concentration of 10%. The tissue was then frozen at a rate of −1° C/min to −70° C and stored in liquid nitrogen at −196° C. After two weeks the cryopreserved islets were thawed in 37° C waterbath and were fixed in formalin. Sections of the pancreases before digestion were also fixed in formalin. All sections were stained for Galα1-3Gal and T F by immunohistology using human anti-Galα1-3Gal antibodies eluted from a sepharose immunoadsorbent column and a mouse anti-T F monoclonal antibody. Results: Results for Galα1-3Gal and T F staining on porcine islets of both pancreases before and after collagenase digestion without (−) and with (+) cryopreservation were as follows: (Table)Tablep-values (×2): p<0.001 for b vs. a, c vs. b, e vs. d and f vs. e The Galα1-3Gal and T F antigens were expressed in the intra-islet capillaries in the pancreas before digestion; their expression was substantially reduced after collagenase digestion and was eliminated after cryopreservation. Conclusions: Cryopreservation eliminates Galα1-Gal and T F expression on adult porcine pancreatic islets which increases the chances of successful pig to human islet xenotransplantation.