Corneal graft rejection in the inbred minipig
Lead Research Organisation:
University of Bristol
Department Name: Clinical Veterinary Science
Abstract
A corneal transplant (replacing the window of the eye) is often needed to restore sight to a damaged or diseased eye. Sadly about one quarter of transplants are rejected by the white cells of our immune system because they see the transplant as foreign. To learn more about how this happens we need models that closely resemble man.
Minipigs could be very valuable in two ways. First, they are similar in size to humans. We therefore expect rejection (involving clouding of the cornea) to resemble human rejection very closely. Second, minipigs are partially inbred, which allows investigation of the immune response in ways that are impossible in very genetically diverse human patients.
During the lifetime of the grant we will test how closely rejection in the minipig resembles human rejection and develop methods of measuring immunity that could be used in the clinic to prevent rejection.
If the minipig proves to be a good model, we can later use it to test new treatments, particularly gene therapy. As we are able to keep donor corneas in tissue culture for up to 30 days, genes to combat possible future rejection can be readily introduced into the cornea before the operation.
Minipigs could be very valuable in two ways. First, they are similar in size to humans. We therefore expect rejection (involving clouding of the cornea) to resemble human rejection very closely. Second, minipigs are partially inbred, which allows investigation of the immune response in ways that are impossible in very genetically diverse human patients.
During the lifetime of the grant we will test how closely rejection in the minipig resembles human rejection and develop methods of measuring immunity that could be used in the clinic to prevent rejection.
If the minipig proves to be a good model, we can later use it to test new treatments, particularly gene therapy. As we are able to keep donor corneas in tissue culture for up to 30 days, genes to combat possible future rejection can be readily introduced into the cornea before the operation.
Technical Summary
Translation of experimental findings from corneal graft rejection research into genuine improvements for patients is hampered by a lack of in vitro or in vivo models that are accurate clinico-pathological correlates of human rejection. Such models are needed both for studying donor-specific immunity and testing anti-rejection therapies (including gene therapy). The aim is to set up and evaluate such a pre-clinical model in the partially inbred Minnesota minipig.
Key goals are:
1) To perform corneal transplants and characterise rejection clinically and by immunofluorescence histology in recipients of allografts fully mismatched at major histocompatibility complex (MHC) and multiple minor loci.
2) To compare the clinical manifestations of rejection with those in man.
3) To determine the contribution of minor antigens to rejection.
4) To set up assays to monitor T cell immunity that could be implemented clinically. Lymphocyte proliferation assays and ELISpot assays to quantify donor-specific cytokine-producing T cells will be used. Lymphocytes from peripheral blood (the source in patients) will be compared with those from lymphoid organs (the usual source in rodents) as a source of T cells for sensitive immunological monitoring. T cell receptor repertoire in graft, anterior chamber, lymphoid organs and blood will be compared by V-beta-specific spectratyping.
5) To determine whether porcine corneal endothelial cells are mitotic in vivo (as in rats and rabbits) or not (as in man). After rejection or after mechanical removal of corneal endothelial cells we will assess whether residual cells are able to proliferate and restore a functional monolayer.
Key goals are:
1) To perform corneal transplants and characterise rejection clinically and by immunofluorescence histology in recipients of allografts fully mismatched at major histocompatibility complex (MHC) and multiple minor loci.
2) To compare the clinical manifestations of rejection with those in man.
3) To determine the contribution of minor antigens to rejection.
4) To set up assays to monitor T cell immunity that could be implemented clinically. Lymphocyte proliferation assays and ELISpot assays to quantify donor-specific cytokine-producing T cells will be used. Lymphocytes from peripheral blood (the source in patients) will be compared with those from lymphoid organs (the usual source in rodents) as a source of T cells for sensitive immunological monitoring. T cell receptor repertoire in graft, anterior chamber, lymphoid organs and blood will be compared by V-beta-specific spectratyping.
5) To determine whether porcine corneal endothelial cells are mitotic in vivo (as in rats and rabbits) or not (as in man). After rejection or after mechanical removal of corneal endothelial cells we will assess whether residual cells are able to proliferate and restore a functional monolayer.
