Development of a proteomic assay for monitoring transplanted cells and tissues

Many chronic disease states may be treatable with emerging regenerative medicine strategies, such as cell replacement and artificial tissues, however, no tests exist for measuring the success of these ground-breaking therapies. For example, liver disease is a large unmet medical need for which the only effective therapy is liver organ transplantation. Transplantation of hepatocytes as a cell suspension rather than transplantation of the whole organ has the potential to provide an alternative therapy that would make the benefits of organ transplantation available to many more patients than currently benefit. This approach has been demonstrated to be feasible in animal models. The success of hepatocyte transplantation in animal models is measured by a blood test. No such test exists to measure success of hepatocyte transplantation in humans. The proposed project will develop a simple blood test for successful transplantation of human hepatocytes in human patients, enabling clinical development of this therapy. The fundamental principle we are building this test on is the ability to detect using mass spectrometry methods differences in the amino acid sequence of secreted donor hepatocyte proteins from the same proteins derived from patient hepatocytes. This strategy has the advantages of rapid assay development, multiplexing, and sensitivity. Preliminary results are presented that demonstrate successful identification proteins in plasma that can distinguish between individuals and, thus, enable differentiation between donor and recipient proteins in plasma. The proposed work will complete assay development for the liver-specific version of this test and validate the test in blood samples obtained from liver disease patients before and after whole organ transplantation. Phase II of this project will qualify the test for measuring transplanted hepatocytes in a prospective trial, assess potential utility as a prognostic test for whole organ transplantation in various liver disease settings, and develop automated and commercializable methods to facilitate adoption.