Porcine hematopoietic cell xenotransplantation in nonhuman primates is complicated by thrombotic microangiopathy

Open Access
Publisher Website
Google Scholar
Abstract
Thrombotic microangiopathy (TM) is a serious complication of bone marrow transplantation (BMT) that resembles thrombotic thrombocytopenic purpura (TTP). In attempting to achieve hematopoietic cell chimerism in the pig-to-baboon model, we have observed TM following infusion of high doses (>1010 cells/kg) of porcine peripheral blood mobilized progenitor cells (PBPC) into baboons. We performed investigations to analyze the pathobiology of this TM and to test therapeutic interventions to ameliorate it. PBPC were obtained by leukapheresis of cytokine-stimulated swine. The initial observations were made in two baboons that underwent a non-myeloablative regimen (NMR) prior to PBPC transplantation (TX) (group 1). We then studied three experimental groups. Group 2 (n = 2) received NMR without PBPC TX. Group 3 (n = 2) received PBPC TX alone. Group 4 (n = 6) received NMR + PBPC TX combined with prostacyclin, low-dose heparin, methylprednisolone, and cyclosporine was replaced by anti-CD40L mAb in five cases. Baboons in groups 1 and 3 developed severe thrombocytopenia (10/high powered field (hpf)), increase in plasma lactate dehydrogenase (LDH) (2500–9000 U/l), transient neurologic changes, renal insufficiency, and purpura. Autopsy on two baboons confirmed extensive platelet thrombi in the microcirculation, and, similar to clinical BMT-associated TM/TTP, no unusually large vWF multimers or changes in vWF protease activity were observed in the plasma of baboons with TM. In group 2, self-limited thrombocytopenia occurred for 10–15 days following NMR. Group 4 baboons developed thrombocytopenia (3) rarely requiring platelet transfusion, minimal schistocytosis (Bone Marrow Transplantation (2001) 27, 1227–1236.

This publication has 37 references indexed in Scilit: