Genetic-engineered control of the immunogeneic state of vascular composite allografts during preservation

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ABSTRACT While being an increasingly used option of reconstruction for severe defects arising from trauma and/or burn injuries, VCA remains limited in use due to the complex ethical calculus of a treatment that improves life quality dramatically, but at the cost of the side effects of long-term immunosuppression. In the longer term the most promising approach is the induction of tolerance by mixed chimerism by bone-marrow co-transplantation. In the shorter term, new strategies for monitoring immunosuppression to enable timely interventions, and reducing immunogenicity of VCAs are necessary for making this treatment more accessible to patients in need. The objective of this application is to develop a functional preservation platform that enables creating engineered VCA grafts by exogenous administration of genetically-modified cells, their preservation in a clinically practicable protocol, and testing the efficacy in reducing immunogenicity in rodent models of rejection and tolerance induction. Biosensor cells will be genetically engineered with a transcription factor response element as a gene promoter to serve as a theranostic, simultaneously driving the secretion of blood-based biomarker and a therapeutic protein to attenuate a rejection response. We will combine this with our perfusion-based supercooled preservation technologies to enable both engraftment of cells and to provide a time-window that makes the utilization of engineered grafts viable in clinical time frames. This objective has been formulated based on our prior work and preliminary results, where we have shown successful engineering of cells with required response characteristics, development of an ex vivo rat limb perfusion system that can serve as a platform for engrafting these cell biosensors into vascular grafts prior to transplant, and demonstrating that transducted cells can remain viable in vivo for up to 4 months. The proposed work would lead to a smart-graft technology that can sensitively measure local tissue signaling would enable practical monitoring and diagnosis of acute rejection episodes, can transform care of transplant patients since compliance issues in medication would be dramatically reduced, and will likely increase the overall efficacy and therefore reduce graft rejections. In the longer term, the preservation methods developed here could also be enabling for tolerance induction in VCA transplants, and therefore allow for their wide-spread use which is not possible currently.