Molecular Delivery of Heparan Sulfate in Wound Regeneration

DESCRIPTION (provided by applicant): The role of proteoglycans and carbohydrate polymers such as heparan sulfate in biological processes are becoming better understood, but this new frontier has only begun to be explored. Tissue regeneration is also an emerging frontier. This proposed research, when completed, will make an important contribution to both the proteoglycan and tissue regenerative fields, with a specific, clinical impact on periodontal regeneration. The objectives of this project are both scientific and developmental in nature. Scientific advancements in the structural and functional understanding of proteoglycans, such as Perlecan, are proposed, along with innovative studies investigating their role as therapeutics in bone healing. Site-directed mutagenesis to the Perlecan core will establish a valuable precedent. One of the major innovations of this technology is the ability to deliver DNA, not protein, to generate natural, endogenous Perlecan expression in the wounds or surgical sites. With this patented technology, a host-glycosylated Perlecan core will be generated in vivo, intended to promote vascularity, proliferation, and differentiation for enhanced healing. In addition to being highly cost-effective, this technology offers a low-cost alternative to the costly recombinant biologic adjuncts already in the marketplace. The development of a safe, effective, and useful product for periodontal bone regeneration is another important objective. Phase I support for this project enabled the creation of a prototype Perlecan expression construct for delivery of sequences encoding domain 1 (D1) of the core protein. In situ heparan sulfate glycosylation of the expressed core was validated, and new bone formation appeared to be enhanced by delivery of the Perlecan D1 expression construct in vivo. This Phase II project proposes to develop important modifications to the prototype Perlecan D1 expression construct, to identify other effective bone graft materials for co-delivery with the Perlecan D1 expression construct, and to test the Perlecan D1 expression construct in guided tissue regeneration. Structural modeling has allowed rational design for site-directed mutagenesis of the Perlecan D1 core sequence to increase glycosylation and enhance growth factor binding, while addition of a COOH-terminal tag on the prototype transgene will enhance development and characterization. Effective bone graft materials for co-delivery with the replication-defective adenovirus system, or with plasmid DNA in liposomes, will be identified from common bone graft materials or by copolymerization with resorbable poly D-lactide microparticles through an industry partnership. Periodontal regeneration in vivo will be assessed by radiographic and volumetric magnetic resonance imaging in a university collaboration, by histomorphometric analysis of new bone, new periodontal ligament, new cementum, and immunohistochemical measurement of osteocalcin at a 3 week and 12 week post-surgical time point. Expression of the Perlecan D1 transgene will be assessed locally and systemically while safety and toxicity of molecular Perlecan and heparan sulfate delivery is investigated.