Factors Affecting Transplant Outcomes in Diabetic Nude Mice Receiving Human, Porcine, and Nonhuman Primate Islets

Abstract

Background In the absence of a reliable islet potency assay, nude mice transplant is the criterion standard to assess islet quality for clinical transplantation. There are factors other than islet quality that affect the transplant outcome. Methods Here, we analyzed the transplant outcomes in 335 nude mice (NM) receiving islets from human (n=103), porcine (n=205), and non-human primate (NHP) donors (n=27). The islets (750, 1000, and 2000 islet equivalents) were transplanted under the kidney capsule of streptozotocin (STZ) induced diabetic NM. Results The proportion of mice that achieved normoglycemia was significantly higher in the group implanted with 2000 IEQ of human, porcine, or NHP islets (75% normoglycemic) versus groups that were implanted with 750 IEQ (7% normoglycemic) and 1000 IEQ (30% normoglycemic). In this study, we observed that the purity of porcine islet preparations (P ≤ .001), islet pellet size in porcine preparations (P ≤ .01) and mice recipient body weight for human islets preparations (P =.013), was independently associated with successful transplant outcome. NHP islets of 1000 IEQ were sufficient to achieve normoglycemic condition (83%). An islet mass of 2000 IEQ, high islet purity, increased recipient body weight, and high islet pellet volume increased the likelihood of successful reversal of diabetes in transplanted mice. Also, higher insulin secretory status of islets at basal stimulus was associated with a reduced mouse cure rate. The cumulative incidence of graft failure was significantly greater in human islets (56.12%) compared with porcine islets 35.57% (P ≤ .001). Conclusion Factors affecting NM bioassay were identified (islet mass, islet purity, pellet size, in vitro insulin secretory capability and mouse recipient body weight) and should be considered when evaluating islet function.

Improved recovery of human islets from young donor pancreases utilizing increased protease dose to collagenase for digesting peri-islet extracellular matrix

“…29,30 However, our in vitro and in vivo functional assessments indicated that the YDP islet integrity and function were intact and not compromised. Increased protease dose necessitates the use of multiple vials of protease, which eventually increase the enzyme cost to isolate islets.…”

“…Islets isolated utilizing IPC from whole pancreas were carefully assessed by measuring viability and function quality, using FDA/PI and GSIR by both static and dynamic glucose challenges respectively. 29 Thirty days after transplantation, the graft-bearing kidney was removed to confirm graft function and stained for H&E (hematoxylin and eosin) and insulin. 28 In addition, 2000 IEQ human islets (after overnight culture) from the IPC group were transplanted under the kidney capsule of diabetic nude mice (n = 22) as described earlier.…”

Single-Donor Islet Transplantation and Long-term Insulin Independence in Select Patients With Type 1 Diabetes Mellitus

“…The need for more than one donor places islet transplantation in contrast to wholepancreas transplantation. Previous clinical (8,9) and basic science (10) studies have identified factors associated with increased islet potency and insulin independence after single-donor islet infusion. Aside from the stress placed on the donor organ pool, receiving islet transplantation from more than one donor increases the risk of recipient sensitization to human leukocyte antigens (7).…”

Human islet function following 20 years of cryogenic biobanking

“…Three days after the induction of diabetes, islets thawed after cryopreservation (2,000 or 4,000 islet equivalents [IEQ]) or freshly isolated islets (3,000 IEQ) were transplanted under the kidney capsules of the mice [32]. Their body weight and blood glucose levels were monitored over 10 weeks.…”