Use of skin grafts programmed to express VEGF-C with biosensor feedback regulation to treat lymphedema

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PROJECT SUMMARY Lymphedema is a morbid musculoskeletal and skin condition affecting a broad population of patients. In the United States, this condition primarily affects individuals who have had lymph node surgery for cancer management; worldwide over 300 million individuals are affected due to lymphatic infection. The affected limb becomes swollen, and develops skin thickening and fibroadipose tissue deposition. Patients experience pain, impaired limb function, chronic wounds, and are at risk for secondary tumors (lymphangiosarcoma). Unfortunately, current therapeutic strategies to treat lymphedema have had limited success. Non-operative management including compression wraps, manual lymphatic drainage, and pneumatic pumps require strict adherence and are time-consuming for patients. Surgical approaches have demonstrated efficacy but require specialized surgical equipment and technical training, limiting the ability to provide this option to the 5+ million affected individuals in the United States. Vascular endothelial growth factor-C (VEGF-C) is a known pro- lymphangiogenic growth factor which has been studied as a drug-based approach to treat secondary lymphedema. Delivery strategies such as adenoviral vectors, scaffolds, and repeat injection have provided important proof-of-concept support for VEGF-C. However, clinical translation has not been realized. Over the past several years, our laboratory has developed a novel technology enabling epidermal stem cells to undergo gene-editing to express biologics of interest. These stem cells are cultured in vitro to produce skin grafts which can be applied to the patient. Our approach has demonstrated efficacy treating diabetes and cocaine abuse through systemic bioavailability in mouse models. In this proposal, we will build on our previous findings to bring this technology closer to clinical utility while broadening its application. First, we will program epidermal stem cells to express VEGF-C and culture these stem cells in vitro, to form skin grafts. To bring us closer to clinical translation, epidermal stem cells will be isolated from human skin. We will demonstrate that skin grafts can produce growth factors for local bioavailability, thereby expanding the use of this technology. We will use these skin grafts in a model of hindlimb lymphedema, thereby demonstrating that this technology has the potential for clinical utility to treat lymphedema isolated to a unilateral limb. Second, we will advance the current skin graft technology by introducing a biosensor mechanism which provides negative feedback regulation of VEGF-C expression. This biosensor will positively impact the translational potential of this therapy, and have broader utility for translation of in vivo “bioreactor” grafts. Upon conclusion of this study, we will have addressed a challenging morbidity experienced by cancer patients (secondary lymphedema), using a novel technology (programmed epidermal stem cells) to expand its utility to include growth factors (VEGF-C) and local delivery.