Development of Type VII Collagen to Accelerate Wound Closure and Inhibit Scarring in Recessive Dystrophic Epidermolysis Bullosa and Other Types of Skin Wounds
Abstract
One of the Fiscal Year 2017 Peer Reviewed Medical Research Program Topic Areas is Epidermolysis Bullosa (EB), a group of diseases that manifests with fragile, blistering skin. The most severe type of EB is Recessive Dystrophic Epidermolysis Bullosa (RDEB), and it is caused by mutations in the gene for type VII collagen (C7). C7 is a protein found in human skin that is required for keeping the two main layers of skin (the epidermis and dermis) together. Patients with RDEB have absent or diminished C7, resulting in skin fragility and blistering. These blisters rupture into large open wounds that cover much of their body and heal with exuberant scarring, which encases their fingers and makes their hands dysfunctional. Our lab has studied C7 for many years, and we have identified regions in the C7 protein that can bind to skin cells and other molecules found in connective tissues such as healing skin. We noticed that in wounds undergoing healing, C7 was diffusely distributed throughout the wound bed instead of where it normally anchors the skin together in unwounded normal skin. We hypothesize that the numerous binding regions in C7 bring together critical cells and connective tissue molecules that are essential for wound healing. Therefore, we tried adding “laboratory-manufactured” C7 (rC7) to skin wounds in non-diabetic and diabetic mice. Remarkably, we observed accelerated wound closure and decreased wound scarring. Unfortunately, mice are loose-skinned animals whose healing process is a less than ideal model for human beings, a species with tight skin. However, pigs are tight-skinned animals whose skin, of all other animals, most resembles human skin and heals in a similar fashion. Therefore, in this proposal we will create standardized full-thickness wounds in domestic pigs and then add rC7 to the wounds using varying doses and schedules. We will record healing parameters like time until wound closure, inflammation, formation of a new dermis, formation of new dermal blood vessels, markers of scarring, and the tensile strength of the healed wound and compare them against controls. The essential question of this proposal is, Will rC7 administered to pigskin wounds accelerate wound closure and reduce scarring in this animal that is the most relevant to human beings? Additionally, our lab has developed the first diabetic pig with delayed wound healing. It is known that patients with diabetes have delayed wound healing, but the cellular mechanism behind this is unknown. Burn wounds also undergo delayed wound healing and heal with excessive scarring. We developed a burn wound pig model that exhibits these characteristics as well. In this proposal, we will assess the responses of non-diabetic, diabetic, and burn wounds to topical application of rC7 in our pig models. Like in burn wounds, wound scarring is exuberant in RDEB. When we used laboratory methods to make skin cells produce more C7, we found that molecular markers of scarring readily diminished. Conversely, when we prevented the cells from making C7, these same markers of scarring increased. C7 avidly binds to a molecule called TGF-beta, which promotes scarring. Another pathway called the autotaxin/lysophosphatidic acid (ATX/LPA) pathway can cause too much activity of TGF-beta. We hypothesize that rC7 dampens TGF-beta-driven scarring, and without rC7, scarring increases. In Aim 2, we will identify if and to what degree the activity of TGF-beta is inhibited when it is bound by rC7. We will also identify which parts of C7 inhibit TGF-beta’s scarring activity. In Aim 3, we will analyze the activity of the ATX/LPA pathway in RDEB skin cells and skin and compare it to normal skin cells to determine if it is overactive. The impact of this research may be immense since the role of C7 in wound healing and scarring has been largely ignored. Using our pig models, we will determine if rC7 is a potential novel wound healing agent, not only for RDEB wounds
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 29, 2018
- Source ID
- W81XWH1810558
Entities
People
- Mei Chen
Organizations
- United States Army
- University of Southern California