C. Rastellini

Indefinite survival of rat islet allografts following infusion of donor bone marrow without cytoablation

We have tested the effect of donor bone marrow cell (DBMC) infusion on the survival of pancreatic islet allografts in the rat, without the use of cytoablative recipient conditioning. Lewis and diabetic Brown Norway rats were used as donors and recipients, respectively. Donor islets were placed beneath the left renal capsule. Infusion of DBMC and temporary immunosuppression followed by delayed islet transplantation resulted in indefinite survival of all islet grafts (MST > 180 days). Control animals demonstrated recurrent hyperglycemia (islet allografts rejection). Donor bone marrow derived cells were detected in the spleen and cervical lymph nodes of BN recipients of LEW bone marrow but not in the recipients of islet transplants alone. Second set full thickness skin grafts were performed in normal BN and in recipients of a previously successful ITX. Donor specific skin grafts were accepted in the animals that had received DBMC 40 days before the islet allograft, while animals receiving DBMC at the time of the islet allograft rejected the donor specific skin graft similarly to the controls. However, these animals did not reject a second set donor-specific islet transplant. The results indicate that radiation conditioning of the recipients was not necessary to induce microchimerism and graft acceptance in this rodent model of islet allotransplantation.

Augmentation of chimerism with perioperative donor bone marrow infusion in organ transplant recipients: A 44 month follow-up☆

A.S. Rao, P. Fontes, A. Iyengar, R. Shapiro, F. Dodson, R. Corry, S. Pham, M. Jordan, A. Zeevi, C. Rastellini, A. Aitouche, F. Egidi, H.A. Gritsch, J. Reyes, J.J. Fung, and T.E. Starzl Thomas E. Starzl Transplantation Institute and the Departments of Surgery (A.S.R., P.F., A.I., R.S., F.D., R.C., S.P., M.J., C.R., J.R., J.J.F., T.E.S.) and Pathology (A.S.R., A.Z.), University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania

An Attempt to Reverse Diabetes by Delayed Islet Cell Transplantation in Humans

Although autotransplantation of islets has been shown to successfully reverse pancreatectomy-induced diabetes, such an outcome is rarely witnessed after islet cell allotransplantation.1,2 To promote acceptance of islets in diabetic patients suffering from end-stage renal disease (ESRD), perioperative infusion of donor bone marrow (BM) to augment chimerism has already been attempted.1,3 A less than desirable outcome of the latter approach has prompted the exploration of alternative strategies which would allow for successful islet cell transplantation (Tx). It has been previously shown that, unlike concomitant Tx, islets implanted subsequent to BM infusion in rodents results in indefinite reversal of streptozotocin-induced diabetes.4 However, despite its uniqueness, the principal limitation for clinical application of this procedure was the unpredictable islet cell recovery encountered using contemporary culture and cryopreservation techniques. Recognizing this predicament, we embarked on developing a novel technique that allowed for prolonged islet cell culture with an acceptable loss of their viability and function.5 This accomplishment motivated the initiation of a clinical trial for delayed islet cell infusion into diabetic kidney transplant recipients, who have exhibited demonstrable immune modulation and are maintained on relatively lower doses of immunosuppression (IS); reported herein is the clinical outcome in these patients.

Treatment of isolated pancreatic islets to reverse pancreatectomy-induced and insulin-dependent type I diabetes in humans: a 6-year experience.

THE SUCCESSFUL isolation and subsequent auto.1 transplantation of islets into pancreatectomized patients has promulgated the possible use of this procedure for the treatment of insulin-dependent type I diabetes (IDOM).1.2 However, our inability to diagnose and promptly treat islet allograft rejection combined with the deleterious effects of currently used immunosuppressive agents have severely limited the clinical utility of this approach. In an attempt to evolve a universally applicable strategy for the surgical treatment of 100M, we at the Thomas E. Starzl Transplantation Institute have performed, between January 1990 and May 1996. 42 pancreatic islet cell transplantations. We report herein, the results of our 6-year experience with this procedure in humans and discuss some of the approaches that we have evolved that may assist in the successful engraftment of allotransplanted islets.

Prolonged survival of islet allografts following combined therapy with tacrolimus and leflunomide

D E NOVO diabetes mellitus is encountered in approximately 10% of patients treated with either Tacrolimus (FK506) or cyclosporin (CSA) within the first year posttransplantation.1.2 This outcome is largely attributed to the direct inhibitory effects of these primary immunosuppressants on pancreatic islet cell function and on their ability to release insulin. While this altered glucoregulatory function can be reversed in the majority of patients by dose reduction, it nevertheless has an adverse influence on long-term patient and graft survival. The latter finding has fomented interest in the discovery of novel immunosuppressive agents, which in addition to preventing rejection, would also be innocuous to f3 cells, thus allowing widespread clinical use of islet cell transplantation (Tx) for the treatment of insulin-dependent type I diabetes mellitus (100M). Leflunomide (LEF) is a powerful immunosuppressive agent, which when used in rats, prevented kidney and skin allograft rejection.3 Interestingly, when used in combination with subtherapeutic doses of CyA, it also enhanced islet allograft survival in preclinical models of diabetes.4 However, the efficacy of LEF used in combination with sub therapeutic, nondiabetogenic doses of FK506 to prevent islet cell rejection, has as yet not been ascertained; this study was therefore designed to address this latter issue.

Adjuvant bone marrow infusion in clinical organ transplant recipients

THE two most common causes of late organ allograft failure are complications associated with the long-term use of nonspecific immunosuppression and chronic rejection. Incidentally, this undesirable outcome could be prevented by timely adoption of clinically applicable strategies that would result in the induction of donor-specific tolerance (DST). We have previously advanced the hypothesis that stable existence of donor cell chimerism in organ allograft recipients may induce DST with ultimate enhancement of patient and graft survival.1,2 To test this hypothesis, we proceeded to augment chimerism in clinical organ transplant recipients by adjuvant perioperative unmodified donor bone marrow (BM) infusion.2,3 Reported herein is the outcome of this prospective trial in which 251 study (BM-augmented) and 129 contemporaneous controls have been accrued since its initiation in June 1992.

Preservation injury and acute rejection of rat intestinal grafts: protection afforded by pyruvate

Pyruvate has been shown to prevent intestinal mucosal injury after ischemia-reperfusion. The aim of the present study was to determine whether pyruvate can (1) prevent postreperfusion mucosal injury occurring after intestinal preservation and subsequent transplantation and (2) exert a protective effect on the intestinal graft mucosa during acute rejection. Preservation mucosal injury was evaluated, after 2 hours of reperfusion, by comparing grafts transplanted in a rat syngeneic combination (ACI to ACI) after 2 hours of cold preservation using pyruvate (n = 6) or placebo (n = 6). Mucosal parameters obtained during acute rejection (allogeneic combination: ACI to Lewis) were compared between placebo-treated (n =6) and pyruvate-treated (n = 6) animals. Tissue injury was evaluated by histopathologic examination, oxygen free radical production by luminol-enhanced chemiluminescence, and degree of neutrophil infiltration by myeloperoxidase staining. After reperfusion of the preserved grafts and during acute rejection, mucosal oxygen free radical levels and the number of infiltrating neutrophils were significantly (P <0.05) increased in the untreated grafts, whereas there was a statistically significant inhibition of these parameters in those treated with pyruvate. Mucosal injury, seen after reperfusion of the preserved grafts, was prevented by pyruvate. The histopathologic abnormalities observed in the untreated grafts during rejection were also significantly reduced by pyruvate. Treatment with pyruvate before cold preservation of intestinal grafts, in this rat model, reduced reperfusion mucosal injury, neutrophil infiltration, and oxygen free radical production. Oxygen free radicals were produced in the mucosa of the graft during acute rejection and their production was reduced by pyruvate, which exerted a protective effect on the rejecting allograft mucosa.

Immune modulation in organ allograft recipients by single or multiple donor bone marrow infusions

The discovery of persistent alloantigen (i.e., chimerism) in the lymphoid and nonlymphoid tissues of successful long-term organ transplant recipients has prompted many to conclude that this phenomenon plays an important role in allograft acceptance.1,2 These findings have been corroborated in experimental models of transplantation (Tx) tolerance.3 Although the precise phenotype of cells involved in the induction of observed donor-specific tolerance (DST) is unclear, there exists overwhelming evidence suggesting that perhaps immature dendritic cells, which are resident within the graft and known to migrate after Tx, modulate host anti-donor effector responses.4 As these cells are of bone marrow (BM) origin, it was rational to propose that perioperative donor BM infusion may augment this phenomenon with resultant salutary effect on patient and graft survivals. In 1992 we initiated a clinical trial involving perioperative infusion of unmodified BM cells obtained from the vertebral bodies of cadaveric donors into abdominal and thoracic organ allograft recipients. An interim analysis of the outcome in these patients is reported at their most recent follow-up.

Mechanisms underlying the development of T-cell tolerance following interruption of signalling at the CD28/B7 and CD40/gp39 interface.

C. Rastellini, A. Salam, R. Kuddus, A. Aitouche, M. Braun, R. Leach, R. Peach, J.J. Fung, T.E. Starzl, and A.S. Rao Section of Cellular Transplantation, Thomas E. Starzl Transplantation Institute and the Departments of Surgery (C.R., A.S., R.K., A.A., M.B., R.L., J.J.F., T.E.S., A.S.R.) and Pathology (A.S.R.), University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania. Bristol-Myers Squibb (R.P.), Inc, Princeton, New Jersey.