Lack of cross-sensitization between α-1,3-galactosyltransferase knockout porcine and allogeneic skin grafts permits serial grafting

Abstract

Background: The current standard of care for burns requiring operative treatment consists of early burn excision and autologous split-thickness skin grafting. However, in large burns, sufficient donor sites may not be available to achieve total coverage, necessitating temporary coverage with allogeneic human cadaver skin grafts or synthetic skin substitutes. A previous study from this laboratory demonstrated that skin grafts from alpha-1,3 galactosyltransferase knockout (GalT-KO) miniature swine enjoyed survival comparable to that of allogeneic skin grafts in baboons.

Methods: In the present study, we have evaluated the immune response against sequential GalT-KO and allogeneic skin grafts to determine whether such serial grafts could extend the period of temporary wound coverage before definitive grafting with autologous skin.

Results: We report that rejection of primary GalT-KO skin grafts led to an anti-xenogeneic humoral response with no evidence for sensitization to alloantigens nor acceleration of rejection of allogeneic skin grafts. Similarly, presensitization with allogeneic skin did not lead to accelerated rejection of xenogeneic skin.

Conclusions: These data suggest that GalT-KO skin grafts could provide an early first-line treatment in the management of severe burns that would not preclude subsequent use of allografts, and that serial grafting of GalT-KO skin and allogeneic skin could potentially be used to provide an extended period of temporary burn wound coverage.

Conflict of interest statement

The authors declare no conflicts of interest.

Figures

FIGURE 1

First set grafting with GalT-KO skin does not cause accelerated rejection of a secondary set allograft and vice versa, a first set allograft does not accelerate rejection of subsequent GalT-KO skin. Representative gross clinical pictures from serially grafted baboons are shown here. The top set show primary GalT-KO (1°G) then secondary allogeneic (2°A) grafts and the bottom set show primary allogeneic (1°A) then secondary GalT-KO grafts (2°G). Data shown is representative.

FIGURE 2

A and B, Primary grafting with GalT-KO skin elicits a strong anti-xenogeneic antibody response but no anti-allogeneic response and vice versa; primary allogeneic skin elicits an anti-allogeneic antibody response but no anti-xenogeneic antibody response. Serum collection time points are designated by postoperative date (POD); the first number is days since primary grafting, and the number in parentheses is days since secondary graft. Presence of anti-xenogeneic and anti-allogeneic IgM and IgG antibodies, in the recipients’ serum, was indirectly assayed by FACS analysis using donor PBMC. The mode of florescence is given for each plot. Data shown is representative.

FIGURE 3

Reactivity of recipients’ serum against xeno- and allo-PBMC was assayed by complement-dependent cytotoxicity assay for the recipients who received a primary xenogeneic graft and a secondary allogeneic graft (A, B) and for the recipients who received a primary allogeneic graft and secondary xenogeneic graft (C, D). Data shown is representative.