Consistent survival in consecutive cases of life-supporting porcine kidney xenotransplantation using 10GE source pigs

Abstract

Xenotransplantation represents a possible solution to the organ shortage crisis and is an imminent clinical reality with long-term xenograft survival in pig-to-nonhuman primate (NHP) heart and kidney large animal models, and short-term success in recent human decedent and clinical studies. However, concerns remain about safe clinical translation of these results, given the inconsistency in published survival as well as key differences between preclinical procurement and immunosuppression and clinical standards-of-care. Notably, no studies of solid organ pig-to-NHP transplantation have achieved xenograft survival longer than one month without CD40/CD154 costimulatory blockade, which is not currently an FDA-approved immunosuppression strategy. We now present consistent survival in consecutive cases of pig-to-NHP kidney xenotransplantation, including long-term survival after >3 hours of xenograft cold preservation time as well as long-term survival using FDA-approved immunosuppression. These data provide critical supporting evidence for the safety and feasibility of clinical kidney xenotransplantation. Moreover, long-term survival without CD40/CD154 costimulatory blockade may provide important insights for immunosuppression regimens to be considered for first-in-human clinical trials.

Fig. 1. 10GE porcine kidneys support life with stable renal function in baboons.

a Survival probability for recipients transplanted with 10GE renal xenografts. One recipient with high levels of preformed antibody to source pig 10GE cells (denoted as “High risk”) hyperacutely rejected graft. The remaining five recipients (denoted as “Low risk” for hyperacute graft loss) lost their grafts on POD165, POD252, POD285, and POD337. b Serum creatinine levels among these five recipients remained within the normal range until the development of irreversible graft failure.

Fig. 2. Four of five xenograft recipients maintained stable graft function beyond six months.

Periodic acid-Schiff staining of xenograft kidney biopsy sample derived from recipients B3520 (A), B1320 (B), B4519 (C), and B0820 (D) at the time of scheduled six-month (POD180) biopsy. Note: biopsy from B3520 (A) was taken on POD214 due to inadequate POD180 specimen. Multiple cuts of each sample were obtained and evaluated with similar findings. The black bar at the bottom right of each panel corresponds to 100 μm.

Fig. 3. Three of five xenograft recipients with histologic evidence of rejection at time of necropsy.

Top panels are periodic acid-Schiff staining of xenograft kidney biopsy sample derived from recipients B3520 (A), B0820 (B), and B4519 (C) at the time of necropsy; Hematoxylin and eosin (H&E) staining of B3520 (D), B0820 (E), and B4519 (F) at time of necropsy. Multiple cuts of each sample were obtained and evaluated with similar findings. The black bar at the bottom right of each panel corresponds to 100 μm.

Fig. 4. Xenograft loss in remaining animals associated with adenovirus infection in the absence of antibody binding in xenograft.

Immunofluorescence staining of IgM (upper panels, A–E) and IgG (middle panels, F–J) of 10GE xenograft biopsies obtained from recipients at time of necropsy, double-stained with CD31 and performed in duplicate to confirm findings. White bar at the bottom right of each (A–J) corresponds to 200 µm. Immunohistochemistry staining for human adenovirus (lower panels, K–O); staining performed in duplicate to confirm findings. Black bar at bottom right of each (K–O) corresponds to 40 µm.

Fig. 5. Expression of human transgenes in 10GE porcine kidneys.

A Transgenic expression of hTBM, hEPCR, hCD47, hHO1, hCD46, and hDAFin kidney tissue as assessed by immunohistochemistry. Top panel is 10GE kidney tissue; bottom panel is wild-type kidney tissue (control). IHC staining was performed twice on each specific kidney sample. Black bar at the bottom right of each panel corresponds to 100 µm. B hTBM, hEPCR, hCD47, hHO1, hCD46 and hDAF expressed at expected molecular weight in 10GE kidney sample. WT tissue lysate acts as negative control. Actin acts as loading control for the assay. Representative data from two independent runs.