The repair of damaged articular cartilage is problematic due to the limited regenerative potential of this tissue. Current procedures used for the repair of articular cartilage may provide symptomatic relief, but are flawed in that no single treatment results in complete regeneration of a fully functional articular surface. Life Cell Corporation's core technology involves processing human tissue in a manner that removes all cellular material yet preserves the bioactive three-dimensional extracellular matrix scaffold. Cymetra consists of micronized extracellular matrix particles and was originally developed for use in plastic and reconstructive procedures involving soft tissue. Recent studies revealed that Cymetra is also remodeled into orthopaedic tissue. The current studies will expand on these initial observations by combining their generative properties of Cymetra with the powerful driving force of gene delivery. The preserved three-dimensional structure of Cymetra does not promote inflammation, is rapidly repopulated with cells and is efficiently remodeled in vivo, making Cymetra an ideal carrier for delivery of genes using Gene Activated Matrix technology. Expression plasmids will be mixed with Cymetra to create Gene Activated Cymetra. Initial studies will establish gene delivery capabilities by implanting Gene Activated Cymetra encoding a Green Fluorescent Protein (GFP) reporter gene subcutaneously and intermuscularly in a mouse animal model. Expression of GFP will be quantified and an optimal plasmid to Cymetra ratio determined. Subsequent experiments will focus on expression of cartilage and bone specific genes in chondrogenic and osteogenic animal models. Expression plasmids encoding the transcription factors sox9 and osterix and the growth factors BMP2, BMP4 and BMP7 will be created. These plasmids will be mixed as part of a Gene Activated Cymetra configuration and delivered subcutaneously and intermuscularly in mice. Explants will be evaluated for chondrogenic and osteogenic changes using various histochemical, immunochemical and biochemical techniques. The data obtained from these studies will be used to establish several lead configurations to be tested for the repair of osteochondral defects and non-union fractures in large animals. It is anticipated that intrinsic regenerative properties of Cymetra, when combined with gene delivery technology, will promote robust and highly efficient repair of orthopaedic tissues.
