Brevig T, Meyer M, Kristensen T, Zimmer J, Holgersson J
Department of Anatomy and Neurobiology, University of Southern Denmark.
Transplantation. 2001 Jul 27;72(2):190-6. doi: 10.1097/00007890-200107270-00004.
Transplantation of embryonic neural tissue is a potential treatment for Parkinson's disease. Because human donor material is in short supply, porcine xenografts are considered a useful alternative. Current immunosuppressive therapies fail, however, to protect intracerebral neural xenografts from host CD4 T lymphocytes. To reduce the immunogenicity of porcine donor tissue, we attempted to remove microglial cells with antibodies against the alpha-galactosyl epitope (Galalpha1,3Galbeta1,4GlcNAc-R), or anti-Gal, and complement, and studied whether this pretreatment can reduce direct and indirect T-cell responses to the tissue.
Brain tissue from 27-day-old pig embryos was dissociated and treated with human anti-Gal and rabbit complement. The microglial content was analyzed by flow cytometry. [3H]thymidine incorporation in cocultures of the brain cells and purified human CD4 T cells was used to determine direct T-cell responses. Indirect T-cell responses were studied by grafting pretreated and control-pretreated (no anti-Gal) nigral tissue into the lesioned striatum of immunocompetent rats with 6-hydroxydopamine-induced hemiparkinsonism. Amphetamine-induced circling behavior was used to measure graft function.
Anti-Gal and complement reduced the microglial content to 11-24% of control and abolished the ability of the brain cells to induce human CD4 T-cell proliferation. Pretreated nigral tissue reduced hemiparkinsonism by more than 50% in five of eight rats at some point during the 10-week follow-up. Rats receiving control-pretreated nigral tissue did not display this degree of improvement.
Pretreatment with anti-Gal and complement can reduce the immunogenicity of porcine neural tissue, and might, therefore, be a valuable alternative or supplement to immunosuppression in neural xenotransplantation.
