This application addresses the thematic area of Translating Basic Science Discoveries into New and Better Treatment. Recessive dystrophic epidermolysis bullosa (RDEB) is an incurable, inherited mechano- bullous disease of the skin characterized by skin fragility, blister formation, and chronic wounds. RDEB is caused by defects in the human gene encoding type VII collagen (C7), the major component of anchoring fibrils (AFs) that anchor the epidermis to the dermis. AFs are attenuated, diminutive, or absent in RDEB. There is no effective treatment for RDEB except palliative measures and supportive wound care. Patients with RDEB die of an aggressive, metastatic, squamous cell carcinoma in the second or third decade of life. We used molecular and cellular approaches to study the structure and function of C7. Using two """"""""preclinical"""""""" mouse models (one with RDEB human skin equivalents transplanted onto athymic mice and the other a RDEB-like C7 knockout mouse), we developed four therapeutic strategies to treat RDEB patients - (i) keratinocyte-based ex vivo gene therapy;(ii) fibroblast based-cell therapy;(iii) lentiviral vector-based therapy;and (iv) recombinant C7 protein therapy. With C7 protein therapy, we showed that intradermal injections of recombinant C7 into human RDEB skin equivalents transplanted onto athymic mice stably restored C7 expression and AFs at the basement membrane zone (BMZ) in vivo and reversed the RDEB disease features. With the C7-knock out mouse model, we demonstrated that the injected human C7 became incorporated into the mouse's BMZ where it created human AFs significantly improved the RDEB disease phenotype by decreasing skin fragility, decreasing new blister formation and markedly prolonging survival. Based on our success with these preclinical animal models, we now plan to attempt C7 protein therapy in RDEB patients and determine the safety and efficacy of this treatment. We will inject C7 intradermally into test sites on RDEB patients and evaluate its safety, efficacy, potential patient immune responses, and the duration of any beneficial effects. Outcomes of a successful trial would be: (i) no local or systemic side effects;(ii) the creation of new C7 and AFs in RDEB patient skin;and (iii) decreased bullae and erosions in C7-treated skin sites. This grant proposal, therefore, conforms well with this RFA's intention of promoting translational research - that is, bringing scientific discoveries from the laboratory to the patient's bedside. We believe this proposed clinical trial could very well lead to the first practical therapy for RDEB. Furthermore, if successful, our proposed study could provide the proof of principle for using protein therapy for other intractable skin diseases due to genetic defects in skin structural proteins.
Recessive dystrophic epidermolysis bullosa (RDEB) is an incurable, devastating, life-threatening bullous disease of the skin with many untoward sequelae. Herein, we will test the safety and efficacy of injecting intradermally type VII collagen in to patients'skin and determine if it restores C7 and anchoring fibrils in their skin and improves their disease. The proposed studies will facilitate future development of protein- based therapy for other inherited skin diseases.
