Clinical xenotransplantation

Abstract

Two baboon liver xenografts transplanted to patients with B virus hepatitis supported life for 70 and 26 days but did not function optimally despite minimum or no histopathologic findings of overt humoral or cellular rejection in serial biopsies. However, there was evidence of complement activation in both cases, which in retrospect was thought to explain the unsatisfactory outcome. Strategies to deal with this problem are discussed.

Fig. 1

Piggyback operation used for both baboon-to-human xenotransplantations.

Fig. 2

Demonstration by Valdivia et al. [17] that the complement environment of a xenograft recipient becomes that of the donor species. In these experiments, the dominant complement of rat recipients of hamster livers become hamster-specific within a few days, a change that was permanent. See text for further explanation.

Fig. 3

Second stage experiments of Valdivia et al. [17] following the engraftment shown in Figure 2, showing species restriction of complement activation. Rats bearing long surviving hamster livers hyperacutely rejected these xenografts when injected with rat anti-hamster serum. but not if the serum was first decompleted by heating.