iPS Cell-Based Treatment of Dominant Dystrophic Epidermolysis Bullosa

Genetic skin diseases constitute a diverse group of several hundred diseases that affect up to 2% of the population and include common disease such as psoriasis, atopic dermatitis, and wound healing. Patients with one genetic disease, dystrophic Epidermolysis bullosa (EB), lack a normal collagen VII (COL7A1) gene and suffer from debilitating blistering which leads to chronic wounds and scarring that can be lethal by young adulthood. The disease is devastating and despite all efforts, current therapy for DEB is limited to wound care. For recessive dystrophic EB (RDEB) where there is no COL7A1 protein, our EB Disease team has shown that retroviral delivery of the COL7A1 using gene transfer provides a powerful disease modifying activity as autologous, cell-based therapy. In this process, the patient' own cells can be induced to make normal collagen VII. The patients can then receive their own corrected cells back onto their skin. While successful, our initial approach cannot treat many dominantly inherited diseases such as dominant dystrophic EB (DDEB) where a poison subunit inhibits the function of the normal protein. Recent development of induced pluripotent stem (iPS) cells that are generated from the somatic cells of individual patients could provide an ideal source of therapy. Because of recent advances by our team and others in stem cell technology, our hypothesis is that we can create genetically corrected iPS cells for dominant skin diseases such as DDEB as well as recessive diseases such as RDEB. The goal of the EB Disease team is to develop iPS cells of patients with DEB and genetically correct the patient's own collagen VII defect. We then plan to convert the iPS cell back into skin cells that can be grafted onto the patient's wounds. We plan to develop the processes necessary for iPS cell generation, genetic correction and development of a product that can be grafted back onto the patient's own skin. We will be working within the Food and Drug Administration (FDA) in order to create this process while meeting the requirement for successful drug development. Among the FDA requirements are Good Manufacturing Practice (GMP) documenting the purity of the created drug. We have made significant scientific progress during the first year of this grant. Using GMP methods we have developed the initial tools required for successful iPS cell development which will meet the FDA requirements for drug development. We have generated iPS cell lines from subjects with documented DEB and began the processes necessary for genetic correction and future skin grafting of the corrected cells back onto the patient. We are doing extensive testing of the iPS-derived skin cells using human skin tissue models to ensure the safety and efficacy of these cells. Soon we will work together with the FDA and our collaborators to generate patient-specific skin grafts. The ability to therapeutically reprogram and replace diseased skin would allow this procedure to develop therapeutic reprogramming approaches for a variety of both common and life-threatening skin diseases. Moreover, genetically-corrected pluripotent iPS cells could form the basis of future systemic therapies to other organs besides the skin to treat common genetic disorders.

Genetic skin diseases constitute a diverse group of several hundred diseases that affect up to 2% of the population and include common disease such as psoriasis, atopic dermatitis, and wound healing. Patients with one genetic disease, dystrophic epidermolysis bullosa (DEB), lack a normal collagen VII (COL7A1) gene and suffer from debilitating blistering which leads to chronic wounds and scarring that can be lethal by young adulthood. The disease is devastating and despite all efforts, current therapy for DEB is limited to wound care. For recessive dystrophic EB (RDEB) where there is no COL7A1 protein, our EB Disease team has shown that retroviral delivery of the COL7A1 using gene transfer provides a powerful disease modifying activity as autologous, cell-based therapy. In this process, the patient's own cells can be induced to make normal collagen VII. The patients can then receive their own corrected cells back onto their skin. While successful, our initial approach cannot treat many dominantly inherited diseases such as dominant dystrophic EB (DDEB) where a poison subunit inhibits the function of the normal protein. Recent development of induced pluripotent stem (iPS) cells that are generated from the somatic cells of individual patients could provide an ideal source of therapy. Because of recent advances by our team and others in stem cell technology, our hypothesis is that we can create genetically corrected iPS cells for dominant skin diseases such as DDEB as well as recessive diseases such as RDEB. The goal of the EB Disease team is to develop iPS cells of patients with DEB and genetically correct the patient's own collagen VII defect. We then plan to convert the iPS cell back into skin cells that can be grafted onto the patient's wounds. We plan to develop the processes necessary for iPS cell generation, genetic correction and development of a product that can be grafted back onto the patient's own skin. We will be working with the Food and Drug Administration (FDA) in order to create this process while meeting the requirement for successful drug development. Among the FDA requirements are Good Manufacturing Practice (GMP), documenting the purity of the created drug. We have made significant scientific progress during the first two years of this grant. We have developed the initial tools required for successful iPS cell development which will meet the FDA requirements for drug development. We have generated iPS cell lines from subjects with documented DEB, identified the genetic mutations, and commenced work on the correction of several mutations in the iPS Cells. We are developing the process necessary for future skin grafting of the corrected cells back onto the patient, and have already successfully generated the initial GMP manufacturing protocols leading to clinical grade, corrected patient skin cells. We are currently doing extensive testing of the iPS-derived skin cells using human skin tissue models to ensure the safety and efficacy of these cells. Soon we will work together with the FDA and our collaborators to generate patient-specific skin grafts. The ability to therapeutically reprogram and replace diseased skin would allow this procedure to develop therapeutic reprogramming approaches for a variety of both common and life-threatening skin diseases. Moreover, genetically-corrected pluripotent iPS cells could form the basis of future systemic therapies to other organs besides the skin to treat common genetic disorders.

Genetic skin diseases constitute a diverse group of several hundred diseases that affect up to 2% of the population and include common disease such as psoriasis, atopic dermatitis, and wound healing. Patients with one genetic disease, dystrophic epidermolysis bullosa (DEB), lack a normal collagen VII (COL7A1) gene and suffer from debilitating blistering which leads to chronic wounds and scarring that can be lethal by young adulthood. The disease is devastating and despite all efforts, current therapy for DEB is limited to wound care. For recessive dystrophic EB (RDEB) where there is no effective COL7A1 protein, our EB Disease team has shown that retroviral delivery of the COL7A1 using gene transfer provides a powerful disease modifying activity as autologous, cell-based therapy. In this process, the patient' own cells can be induced to make normal collagen VII. The patients can then receive their own corrected cells back onto their skin. While successful, our initial approach cannot treat many dominantly inherited diseases such as dominant dystrophic EB (DDEB) where a genetically abnormal poison subunit inhibits the function of the normal protein. Recent development of induced pluripotent stem (iPS) cells that are generated from the somatic cells of individual patients could provide an ideal source of therapy. Because of recent advances by our team and others in stem cell technology, our hypothesis is that we can create genetically corrected iPS cells for dominant skin diseases such as DDEB as well as recessive diseases such as RDEB. The goal of the EB Disease team is to develop iPS cells of patients with DEB and genetically correct the patient's own collagen VII defect. We then plan to convert the iPS cells back into skin cells that can be grafted onto the patient's wounds. We plan to develop the processes necessary for iPS cell generation, genetic correction and development of a product that can be grafted back onto the patient's own skin. We are working within the Food and Drug Administration (FDA) in order to create this process while meeting the requirement for successful drug development. Among the FDA requirements are Good Manufacturing Practice (GMP) documenting the purity of the created drug. We have made significant scientific progress during the first three years of this grant. We have developed the initial tools required for successful iPS cell development which will meet the FDA requirements for drug development. We have generated iPS cell lines from subjects with documented DEB. In addition, we have identified the genetic mutations in the iPS cells and corrected several mutations. We are developing the process necessary for future skin grafting of the corrected cells back onto the patient and have already successfully generated the initial GMP manufacturing protocols leading to clinical grade, corrected patient skin cells. We are currently doing extensive testing of the iPS-derived skin cells using human skin tissue models to ensure the safety and efficacy of these cells. The ability to therapeutically reprogram and replace diseased skin would allow this procedure to develop therapeutic reprogramming approaches for a variety of both common and life-threatening skin diseases. Moreover, genetically-corrected pluripotent iPS cells could form the basis of future systemic therapies to other organs besides the skin to treat common genetic disorders.

Patients with recessive dystrophic epidermolysis bullosa (RDEB) lack functional type VII collagen owing to muta tions in the gene COL7A1 and suffer severe blistering and chronic wounds that ultimately lead to infection and development of lethal squamous cell carcinoma. The discovery of induced pluripotent stem cells (iPSCs) and the ability to edit the genome bring the possibility to provide definitive genetic therapy through corrected autolo- gous tissues. We generated patient-derived COL7A1-corrected epithelial keratinocyte sheets for autologous grafting. We demonstrate the utility of sequential reprogramming and adenovirus-associated viral genome editing to generate corrected iPSC banks. iPSC-derived keratinocytes were produced with minimal heterogeneity, and these cells secreted wild-type type VII collagen, resulting in stratified epidermis in vitro in organotypic cultures and in vivo in mice. Sequencing of corrected cell lines before tissue formation revealed heterogeneity of cancer-predisposing mutations, allowing us to select COL7A1-corrected banks with minimal mutational burden for downstream epidermis production. Our results provide a clinical platform to use iPSCs in the treatment of debilitating genodermatoses, such as RDEB.