Past Funded Research Project – Transplant Immunology

Endothelial Barrier in Allograft Rejection and Tolerance

Primary Investigators: Dr. Austin Schenck, MD

Institution: Ohio State University

Funding began in 2019.

This study was funded in 2019, with a focus on how heart transplantation provides extraordinary, life-saving treatment for patients with advanced heart disease but unfortunately, heart transplantation does not restore a normal life expectancy. The recipient’s immune system slowly damages the transplanted heart and eventually causes it to stop functioning. This happens because the destructive portion of the immune system overwhelms the regulatory portion of the immune system. This study aims to better understand how both the destructive and regulatory sides of the immune system work. Our ultimate goal is to augment the regulatory side of the immune response to transplant so that a heart transplant will last for the natural life of the recipient.


Please read below to learn more about this research project or click here to view the progress report.

The overarching goal in our laboratory is to improve long-term outcomes in heart transplantation such that transplantation will restore normal life expectancy.  Immunosuppression is necessary following transplantation but current best-available drugs have undesirable and toxic side effects that shorten the life-span of recipients.  We hope to replace traditional pharmaceuticals with adoptive immunotherapy.  Adoptive immunotherapy is the deliberate transfer of specific cell populations that can turn off anti-graft immune responses using natural regulatory mechanisms that are not harmful to the recipient.
In work made possible by Enduring Hearts and the American Heart Association, our laboratory has identified a unique cell population with great potential in adoptive immunotherapy.  We have learned how to isolate these cells, keep them alive in culture, and expand their numbers.  We have used modern genomic techniques to analyze all of the genes expressed by these cells which gives us a picture of the ‘tools’ that these cells use to turn off immune responses.  We have sequenced specific receptors expressed on the surface of these cells that, when activated, shift these cells into an active state.  We are now beginning to test what ‘dose’ of these cells will be required to allow long-term acceptance of heart transplants without traditional pharmaceuticals.  This work would not have been possible without the vision and generosity of Enduring Hearts and the American Heart Association.  We look forward to future opportunities to extend this work in clinical trials.

Heart transplantation becomes the only option for survival for patients with advanced heart failure who have exhausted other medical and surgical treatment options. 71,207 heart transplants have been recorded in the United Network of Organ Sharing (UNOS) database, each providing a medical ‘second chance’ for recipients otherwise facing death. Despite these remarkable successes cardiac transplantation is a temporary cure because rejection limits the lifespan of transplanted organs. Both rejection and tolerance require transendothelial migration of donorreactive T cells into allograft tissue. Whether or not T cell recognition of cognate antigen within the vasculature is prerequisite to transendothelial migration is unknown. Likewise little is known about the repertoire and specificity of T cell infiltrates within tolerant allografts. Our preliminary data in murine models of cardiac transplantation suggest that endothelial cell presentation of alloreactive major histocompatibility molecules (MHC) is an absolute requirement for transendothelial migration. Likewise, our preliminary data suggest that T cell infiltrates within cardiac isografts are completely self-restricted leading to the hypothesis that these are endogenous self-reactive regulatory cells. To better understand these questions fundamental to both rejection and tolerance we propose the following specific aims: 1) we will utilize a novel transplant model in which ovalbumin peptide presented in the context of the MHC molecule Kb is restricted to endothelial cells thereby allowing us to directly measure the ability of Kb restricted OT-1 transgenic T cells to extravasate in the presence and absence of cognate ligand on the endothelium; 2) we will utilize CDR3-based next generation sequencing to define the T cell receptor repertoire of isograft-infiltrating T cells; 3) we will perform in-vivo expansion of isograft infiltrates and test their regulatory capacity in adoptive immunotherapy models. These data will answer fundamental mechanistic questions about alloendothelium, generate rationale for manipulation of the endothelium in organ engineering, and better inform already-ongoing clinical trials of regulatory adoptive immunotherapy. Ultimately, these discoveries will translate into better therapy for the 3,897 patients currently awaiting cardiac transplantation.


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