Comparison of the fates of Ag-B locus compatible homografts of skin and hearts in inbred rats

Feasibility, reproducibility, risks and benefits of face transplantation: a prospective study of outcomes

Composite tissue allotransplantations can be indicated when autologous transfers fail to restore human appearance. We report the reproducibility, difficulties, serious adverse events and outcomes of our patients. Five patients were included in a registered clinical research protocol after thorough screenings assessed by an independent expert committee systematically discussing the alternative options. One patient suffered from plexiform neurofibromas, two from third degree burns and two from gunshot injuries. They were included on a national waiting list with a dedicated face procurement procedure. Transplants were harvested from heart beating brain-dead donors before other tissues and organs. Induction immunosuppressive therapy included antithymocyte globulins, steroids, mycophenolate mophetil and tacrolimus. Maintenance therapy included the last three ones associated with extracorporeal-photopheresis. Four patients were transplanted with 7- to 38-month follow-up. One could not due to multiple panel reactive antibodies after 18 months on waiting list. Acute cellular rejections were controlled by conventional treatment. Opportunistic infections affected all patients and lead one patient to die two month after the transplantation. Voluntary facial activity appeared from 3 to 5 month. Face transplantation has been reproducible under conventional immunosuppression. Major improvements in facial aesthetic and function allowed patients to recover social relations and improved their quality of life.

Long-Term Survival of Human Skin Allografts in Patients with Immunosuppression

Severe burn patients lack adequate skin donor sites to resurface their burn wounds. Patients with severe burn injuries to areas such as an entire face are presently reconstructed with skin grafts that are inferior to normal facial skin. This study was designed in part to determine whether human skin allografts would survive, repopulate, and persist on patients with immunosuppression and after discontinuation of immunosuppression. Small split-thickness skin grafts were synchronously transplanted at the time of renal transplantation from six renal transplant donors to recipients. All six patients were immunosuppressed with the usual doses of renal transplant immunosuppressants (methylprednisolone, cyclosporine, prednisone, and azathioprine). The skin allografts were biopsied when rejection was suspected and at various intervals. Special histologic studies were performed on skin biopsy specimens. Class II DNA tissue typing was performed on transplanted and autogenous skin biopsy specimens of four patients. Fluorescent in situ hybridization was performed successfully on skin biopsies of four patients' transplanted skin and on two of these four patients' autogenous skin. All six human skin allografts sustained a 100 percent take and long-term clinical survival. DNA tissue typing performed on skin allograft biopsy specimens from patients taking immunosuppressants all revealed donor and recipient cells. DNA tissue typing performed on autogenous skin biopsies from the same patients all revealed only recipient cells. Fluorescent in situ hybridization performed on allograft and autogenous specimens from patients taking immunosuppressants revealed transplanted donor cells with rare recipient cells in the allograft and only recipient cells in the autogenous skin. This study of six patients proves that it is possible for human skin allografts to survive indefinitely on patients taking the usual dosages of immunosuppressants used for renal transplantation. There was minimal repopulation of skin allografts by autogenous keratinocytes and fibroblast while patients were taking immunosuppressants. Immunosuppression was discontinued in two patients after renal transplant rejection after 6 weeks and 5 years. When immunosuppression was discontinued after 5 years in one patient, the skin allograft cells were destroyed and replaced with autogenous cells, but the skin graft did not reject acutely and persisted clinically. It is hypothesized that the acellular portion of the skin allograft was not rejected acutely because of relatively low antigenicity and because it acted as a lattice for autogenous cells to migrate into and replace rejected allograft skin cells. No chimerism was seen in autogenous skin in the skin-renal transplant patients in this study.

A rat small bowel transplant model of chronic rejection: histopathologic characteristics

BACKGROUND

The major impediment to long-term success in solid organ transplantation is the development of chronic rejection (CR). The vascular lesion of CR, transplant vascular sclerosis (TVS) is characterized by neointimal smooth muscle cell proliferation, and is driven by both immune- and nonimmune-mediated mechanisms. Although the features of chronic heart and kidney allograft rejection have been well characterized, the more immunogenic small bowel allograft has not received similar study.

METHODS

F344 small bowel (SB) was transplanted heterotopically into Lewis recipients that were treated with low-dose Cyclosporine A for 15 days. Lewis recipients of F344 or Lewis SB grafts without immunosuppression, served as controls. Grafts were assessed histologically when recipients showed clinical signs of rejection or at predetermined time points. The immunological components involved in the chronic rejection process were evaluated by immunohistochemical staining.

RESULTS

All SB allografts (100%) developed histologic evidence of CR Cyclosporine A. TVS was seen in 36 of the 46 (78%) of these allografts. The median time to develop TVS was 45 days. Immunohistochemical staining of chronically rejected grafts showed infiltration predominantly by CD4+ cells and macrophages, uniform up-regulation of class II MHC molecule expression, moderate to intense ICAM-1 staining in grafts harvested at postoperative day 45, and uniform neointimal cell staining for smooth muscle cell alpha-actin in the TVS lesions.

CONCLUSIONS

This F344 to Lewis SB transplant model is a useful model that reproduces significant features of CR. The highly immunogenic nature of the SB allografts allows this model to serve as a stringent test for protocols designed to prevent CR.

Chronic rejection in experimental cardiac transplantation: studies in the Lewis-F344 model

Despite recognition of chronic vascular injection by numerous investigators since the beginning of experimental and solid organ transplantation, the pathogenesis of graft arteriosclerosis remains poorly understood. We have defined a reproducible model of this disease by transplanting heterotopic cardiac grafts across minor histocompatibility barriers using inbred strains of rat. We found that long-term surviving Lewis grafts in untreated F344 recipients are subjected to a chronic rejection process which results in the development of diffuse graft arteriosclerotic lesions, indistinguishable in appearance from those seen in human cardiac grafts. Immunohistochemical studies confirm that end-stage lesions are similar in composition to human lesions, made up predominantly of vascular smooth muscle cells with occasional monocytes and T cells. Analysis of serial rejecting allografts demonstrates that a distinct inflammatory stage precedes smooth muscle cell accumulation in areas of intimal thickening, suggesting that mononuclear cells play a role in the developing lesion. Endothelial expression of class II and ICAM-1 appears to lead to early mononuclear cell adherence to the endothelium. Analysis using quantitative RT-PCR confirms that MCP-1 is expressed by ED1-positive monocyte/macrophages in rejecting cardiac grafts, suggesting that this chemoattractant may help drive mononuclear cell accumulation in the expanding intima. Immunohistochemical labelling of PDGF, TNF, and IL-1 in vascular lesions suggests that these growth factors may trigger intimal vascular smooth muscle cell proliferation in chronically rejecting allografts. Hypercholesterolemia did not enhance the severity of lesion development in long-term surviving allografts, suggesting that lipid levels are not a major etiologic factor in graft arteriosclerotic lesion formation in the Lewis-F344 model. Finally, the dietary manipulation of EFAD reduced graft infiltration by mononuclear cells and markedly diminished arterial lesion development in chronically rejecting grafts. Heparin anologues have previously been shown to inhibit proliferative vascular smooth muscle cell lesions in rats following endothelial injury (Clowes & Karnovsky 1977), and we are currently assessing the role of heparin in the therapy of graft arteriosclerosis in the Lewis-F344 model. We are also investigating the role of CD4-positive mononuclear cells in the pathogenesis of lesion development, using the anti-CD4 monoclonal antibody BWH-4 to deplete recipients of CD4-positive cells (Sayegh et al. 1991). In summary, our studies in the Lewis-F344 model suggest that monocyte/macrophages play an important role in the pathogenesis of cardiac graft arteriosclerosis. Future studies utilizing this model should help further elucidate the mechanisms resulting in--and help define potential therapies for--chronic rejection in cardiac transplantation.

Studies of the immediately vascularized skin allograft

In order to evaluate the effect of the nature of revascularization on survival rates of skin allografts, a rat model was devised which provided simultaneous and immediate establishment of arterial and venous blood supply to a composite skin-renal allograft. For 5 days after transplantation the skin portion of the composite grafts appeared normal, with minimal inflammation in 11 recipients. From 6 to 11 days, in 6 rats, active rejection developed with a marked inflammatory reaction of the skin-kidney interface. In 10 rats in which the composite grafts remained in the secondary hosts for 12--21 days rejection of the skin was complete. The renal portion of all composite grafts appeared normal in all three panels and all recipients of composite grafts rejected subsequent orthotopic skin grafts in an accelerated manner, with median survival time of 8.2 +/- 0.3 days compared with 11.5 +/- 0.7 days in untreated Fisher leads to Lewis controls. These results demonstrate that the skin on the composite graft retained its immunogenicity, that immediately vascularized skin allografts between AgB compatible rats will be rejected in a normal time and that anatomical factors are not sufficient to account for the difference in survival times between skin and solid organs.

Serologically demonstrable alloantigens of mouse epidermal cells

Single cells were prepared from mouse tail epidermis by a method which gives high viability counts and so permits their use in cytotoxicity tests. According to tests with standard alloantisera, the antigen phenotype of mouse epidermal cells is H-2(+)theta(+)Sk(+)H-Y(+)TL(-)Ly-A(-)Ly-B,C(-)PC(-). The skin differentiation alloantigen Sk, which is responsible for homograft reactions directed selectively against skin, is expressed also on brain, but not on other cell types; it is present on the transplanted neuroblastoma C1300. Cytotoxicity tests with epidermal cells of H-2 congenic mouse stocks confirm that the Sk locus is not closely linked to H-2. The lymphoid cell differentiation antigen theta also is present on both epidermal cells and brain. Mice frequently retain theta-incompatible or Sk-incompatible skin grafts although they have formed substantial titers of theta or Sk antibody in response to grafting. Male (H-Y) antigen is demonstrable on epidermal cells by cytotoxicity tests with H-Y antibody, as it is also on one other type of cell, spermatozoa.

Histocompatibility studies in a closely bred colony of dogs. 3. Genetic definition of the DL-A system of canine histocompatibility, with particular reference to the comparative immunogenicity of the major transplantable organs

The segregation of the canine DL-A leukocyte group antigen(s) b, c, d, e, f, g, h, k, l, and m has been traced in 141 consecutive matings in the Cooperstown Colony of beagles. All of the leukocyte antigen(s) were regularly transmitted en bloc from parent to offspring, with no instance of independent segregation. A total of 23 haplotypes, including six different DL-A antigen patterns (gl, bkhfm, bkcd, e, be, fgl) was observed. 31 different DL-A phenotypes were observed in a population of 100 mongrel dogs. A number of statistically significant positive and negative associations between individual DL-A antigenic components occurred in this population. The results support the concept of the DL-A system as a complex immunogenetic system governed by a single region (or locus) of an autosomal pair of chromosomes. Studies of skin, kidney, heart, and liver allografts in the Cooperstown Colony indicated that the longest allograft survivals occur under genetically and serologically defined conditions of donor-recipient DL-A compatibility. Skin and renal allografts generally behaved in parallel fashion, while cardiac allografts survived for longer periods of time (MST = 47.1 days) than kidneys (MST = 28.1 days) or skin (MST = 25.1 days) under conditions of DL-A identity. Heart transplants were rejected at a more rapid rate than kidney, however, in DL-A-incompatible donor-recipient combinations. Liver transplants were accorded the longest survival time (MST = 76.2 days) under conditions of DL-A identity, but were rejected at a rapid rate (MST = 5 days) in DL-A-incompatible nonlittermate donor-recipient pairs. The results provide further evidence that the DL-A system is the principal system of histocompatibility in the canine species. The differences in survival of different organs under similar conditions of donor-recipient DL-A compatibility suggest, however, the existence of a number of unknown variables which may also be capable of significantly affecting allograft behavior.