Summary This continuation research proposal (in its 12th year) is a total departure from its original title (on “Mechanism of Human Dermal Fibroblast Motility”), since our discovery of the keratinocyte-secreted form of heat shock protein-90alpha (Hsp90α) as a potent pro-motility factor and a novel wound healing agent by our laboratory in 2007 (Li et al, EMBO J). The development of human recombinant Hsp90α protein as a new treatment for (chronic) diabetic foot ulcers entered its industrial (GMP) phase in 2013 and is under preparations for clinical trials. During the previous funding cycle of Hsp90α, we established a new pig wound healing model for burns that recapitulates the clinical characteristics of burn wounds in humans. Using this model, we have made and reported a new discovery for topically applied Hsp90α to become potentially the first therapeutic treatment of burn wounds (Bhatia et al, Molecular Therapy, 2016). Here is the reason why. Burn injuries are different from all other (acute or chronic) types of wounds by going through an unique event of so-called secondary burn wound progression following the injury, in which a burn expands both horizontally and vertically from its initial boundary to a larger area within the first 1-2 weeks. Therefore, any effective therapeutics must show dual abilities of 1) preventing the secondary burn wound progression and 2) thereafter promoting burn wound re-epithelialization (i.e. closure). Currently there is no FDA-approved therapeutics for burns. We reported that topically applied Hsp90α protein is such a dual functional therapeutics that promotes burn wound healing. First, Hsp90α prevents the secondary burn wound progression by protecting the surrounding cells from undergoing heat-induced Caspase-3 activation and apoptosis. Thereafter, Hsp90α accelerates burn wound healing by stimulating keratinocyte migration-led re-epithelialization, leading to wound closure. This is the first report for a single polypeptide that shows such dual therapeutic functions as required for effective treatment of burn wounds. The goal of this continuation proposal is to elucidate 1) how the secondary burn wound progression takes place, i.e. necrosis versus apoptosis, and 2) how topical Hsp90α prevents secondary burn wound progression. Finally, we will establish a new therapeutic entity (NTE), called Fragment-8, of Hsp90α for drug development. Accomplishment of these preclinical studies will lay the foundation for clinical trials. 1

Narrative The discovery of the keratinocyte-secreted form of the intracellular chaperone protein called heat shock protein alpha (Hsp90α) as a potent wound healing promoting factor in 2007 continues to show new promises, after the development of its full-length and its F-5 fragment entered the industrial phase in 2013. During the previous 4-year funding cycle, we discovered the second important property of topically applied Hsp90α: preventing heat-caused cell death and the secondary burn wound progression, a distinct clinical event for burns. Together with its already known property of promoting the keratinocyte migration-driven wound re-epithelialization, outcomes of this research proposal may lead to a new and the first topical treatment (in forms of cream and/or spray) of burn wounds.