Long-Term Function of Islet Allografts Transplanted on the Omentum Using a Biological Scaffold

Abstract

The liver is the preferred site for islet transplantation (ITx) but not ideal due to limitations affecting engraftment. We evaluated the safety and efficacy of ITx in the omentum using a resorbable biological scaffold in 3 subjects with type 1 diabetes and negative C-peptide. Islets were combined with autologous plasma and thrombin to generate a biologic scaffold and layered laparoscopically on the omentum. Induction was with anti-thymocyte globulin and etanercept. Maintenance was with mycophenolate sodium and tacrolimus. Demographics, islet dose and metabolic data are shown in the Table.Subject #Age (years)Duration T1DM (years)BMI (Kg/m2)IEQ†/KgMMTT‡ Stimulated Glucose (mg/dl)/C-peptide (ng/ml)Insulin dose U/Kg/day (Units/day)HbA1c%6 months12 months24 monthsPre-ITxLatestPre-ITxLatest1432621.511,386181/3.32277/1.79317/0.490.62 (33)0.14 (7)6.85.32321625.39,635372/0.88374/0.65332/0.52*0.45 (31)0.45 (30)5.75.6346422412,648277/2.47--0.45 (20)0.2 (11)6.36.3* 18 months Post-ITx † IEQ= islet equivalents ‡ MMTT = mixed meal tolerance test Subject 1 was insulin independent for 15 months and maintains stable glycemic control. Subject 2 had marginal graft function with persistence of severe hypoglycemia (SH) and then underwent intrahepatic ITx resulting in insulin independence. Subject 3 had a 55% reduction in insulin dose and maintains excellent glycemic control. Our initial experience demonstrates feasibility and safety of ITx on the omentum. Graft function persisted throughout follow-up (6-24 months) resulting in improved glycemic control and absence of SH (subjects 1 and 3). Results suggest a significant loss of islets early post-ITx followed by gradual functional decline similar to intrahepatic ITx. Strategies to improve oxygen delivery and neo-vascularization and minimize immunosuppression are needed to improve long-term outcomes at this site. Disclosure D. Baidal: None. C. Ricordi: None. D.M. Berman: Stock/Shareholder; Self; Pfizer Inc. A. Pileggi: Stock/Shareholder; Self; Converge Biotech, Inc.. Stock/Shareholder; Spouse/Partner; Converge Biotech, Inc. A.M. Alvarez Gil: None. N. Padilla: None. G. Ciancio: None. E. Linetsky: None. R. Alejandro: None.