Effect of cryopreservation on the survival and function of murine islet isografts and allografts

We compared the efficacy of fresh and frozen/thawed islets by determining the minimum number required to consistently reverse diabetes in mice. Defined numbers of islets, isolated from Balb/c (H-2(d)) and CBA/J (H-2(k)) mice, were transplanted into streptozotocin-induced diabetic Balb/c mice. Frozen/thawed grafts were cooled slowly to -40 degrees C, stored at -196 degrees C, and thawed rapidly. At 100 days after transplantation, isografts were recovered for measurement of insulin content. Mean (+/-SD) recovery of cryopreserved islets after thawing was 80 +/- 3% (range 67-89%). For both fresh and frozen/thawed isografts and allografts, 200 islets were required to establish normoglycemia, The degree of metabolic function provided by equivalent quantities of fresh and frozen/thawed grafts was similar; and all normoglycemic isograft recipients remained so until graft nephrectomy, The insulin content of fresh and frozen/thawed isografts containing 200 and 300 islets were 151 +/- 25 and 126 +/- 8 mU and 259 +/- 36 and 278 +/- 20 mU, respectively. Among allograft recipients, median survival ranged from 15 to 20 days, and was not influenced by cryopreservation or graft size. The results of this study demonstrate a high rate of recovery of viable islets following cryopreservation. The function of equivalent quantities of fresh and cryopreserved islet isografts and allografts in nonimmunosuppressed recipients is similar, (C) 1998 Elsevier Science Inc.