Testing the Therapeutic Potential of iPS Cells for Inherited Skin Diseases

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Project Summary No effective treatments are available for epidermolysis bullosa (EB), a group of rare inherited blistering disorders that can be devastating and in some cases lethal. The technological breakthrough that allows adult skin cells to be reprogrammed into induced pluripotent stem cells (iPSCs) now offers the possibility of developing a permanent corrective therapy for EB. The therapeutic approach relies on the generation of patient-specific iPSCs, which then undergo genetic correction and differentiation into skin cells suitable for transplantation. The generation of iPSCs from the same patient in need of treatment would not only potentially avoid the complication of immune rejection, but also provide an unlimited and scalable source of patient- specific cells suitable for transplantation. For the initial studies funded by the parent R01, we focused on developing an iPSC-based therapy for a cohort of patients suffering from the Dowling-Meara subtype of EB simplex (EBS-DM), who share the same R125C “hot spot mutation” in the keratin 14 (Krt14) protein that is responsible for 70% of the EBS-DM cases. This EBS-DM study has allowed us to address all of the major obstacles and pre-requisites required for the development of a clinically relevant iPSC-based therapy for EBS. Specifically, we have developed a novel, efficient method for the generation of clinically relevant integration- free iPSCs. We have also used non-integrating selection marker-free gene editing technology to successfully correct the genetic defect in iPSCs generated from an EBS patient. In addition, our high-efficiency of reprogramming has recently allowed us to combine gene editing and reprogramming of EBS fibroblasts into a one-step procedure. This revision application is proposing to expand the one-step combined gene editing and reprogramming approach to a more severe form of EB, recessive dystrophic EB (RDEB) and to advance our findings toward a clinical trial. Given that the collaborative efforts among several groups will be required to ensure the successful translation of complex iPSC-based therapies into the clinic, we have recently entered into a consortium with Stanford and Columbia Universities to facilitate the development of an optimal manufacturing protocol for genetically corrected iPSC-derived cell products for RDEB treatment. Therefore, Aim 1 of this proposal is to improve the safety and reduce the manufacturing complexity of an iPSC-based therapy for RDEB by combining reprogramming and gene editing into a one-step procedure; Aims 2 and 3 are to manufacture cGMP-compliant reagents for reprogramming and gene editing respectively to assist the Consortium in generating Investigational New Drug (IND) - enabling data for the FDA. The EB iPS Cell Consortium’s success in obtaining approval for a clinical trial for RDEB would expand the therapeutic potential of iPSCs for the treatment of a variety of monogenic diseases affecting other internal organs, where the difficulty in monitoring adverse effects of an iPSC-based therapy would make them unlikely first targets.