Hepatocyte Surface Engineering for Improved Post-transplant Viability The long term objective of our research is to demonstrate the significant potential of covalently-modified live cells or tissues in biomedical applications. The chemical modification of biological surfaces can be utilized to attenuate or enhance native characteristics or to endow these substrates with novel capabilities. We believe that covalently- modified cells can provide a unique therapeutic advantage in cell transplantation, and have reported covalently- modified drug-eluting pancreatic islets exhibiting superior survival and engraftment in a murine model of islet transplantation. We have recently demonstrated several effective methods for the covalent modification of primary rodent and human hepatocytes that provide durable conjugates while retaining cell viability and functionality. In this proposal, we describe experiments focused on altering the characteristics of primary hepatocytes using three distinct strategies: by installing surface camouflage to minimize juxtracrine signaling; by incorporating specific signaling molecules to promote enhanced/altered juxtracrine signaling; and by conjugating small-molecule therapeutics designed for slow release, pharmacologically promoting a localized advantageous effect. It is anticipated that the studies described herein will provide insights into the most promising strategies for enhancing cell survival in hepatocyte transplantation, and future work will be focused on developing those methods further towards application in the clinic. Additionally, these experiments are designed to be foundational studies, enabling future work exploring the surface chemistry of other cells or tissues with promise in transplantation or therapy, investigating different platforms for surface camouflage or different compounds and pathways for juxtracrine signaling, and evaluating alternative bioactive small-molecules with a wide array of targets. In addition to being an innovative research project, the proposed project will significantly enhance the biomedical research environment at Baylor University, an undergraduate-focused institution. Immersed in an integrated interdisciplinary biomedical research project where they participate in both the basic and the translational aspects of a research project, these undergraduate researchers will gain experience as part of a very collaborative team, helping them to gain a greater appreciation for the significance of the many diverse components of the biomedical research enterprise. The overall research hypothesis is that the ex vivo covalent modification of hepatocytes prior to transplantation represents a general strategy for providing cell-surface camouflage as well as the localized and sustained delivery of potent small molecule drugs, and that this strategy can be implemented to significantly reduce early acute cell loss and inflammation and improve engraftment in a hepatocyte transplantation model. The following specific aims are proposed: 1. Hepatocytes with dense PEG surface-camouflage will be prepared and characterized 2. Hepatocytes with covalent CD-47 peptide surface-modification will be prepared and characterized 3. TAK-242-eluting hepatocytes will be prepared and characterized
Hepatocyte Surface Engineering for Improved Post-transplant Viability Transplantation, regardless of the organ, tissue, or cells transplanted, is a demanding procedure that inevitably results in significant cell damage and death, the release of cellular debris including damage-associated molecules, and the subsequent activation of a myriad of molecular and cellular pathways including innate inflammation. Cell transplantation presents a special challenge due to the complete exposure of donor cells to host tissues and blood, and it is routinely reported that the majority of transplanted cells are destroyed in the first hours after transplant, severely limiting the effectiveness of cell transplant procedures. We have recently demonstrated that we can effectively covalently modify hepatocyte surfaces using multiple chemical approaches while retaining cellular viability and function, and propose to evaluate this methodology for the protection of transplanted cells by three different strategies ? the installation of a passive surface coating/antigen camouflage; the presentation of CD47 ?self? peptides; and the localized and sustained delivery of a potent anti-inflammatory small-molecule.
