Recent Patents on Cell-based Approaches to Collagen Enrichment and Repair

Collagen is the most abundant protein in mammals and comprises about ninety percent of connective tissue. Thus, defective collagen can cause many health problems, particularly in the musculoskeletal system, including degenerative joint disease, degenerative spinal disc disorder, disc herniations, tendonitis/osis, osteoporosis, sprains and strains, etc. These pathological conditions, plus the fact that the tensile strength of tissues is essentially provided by collagen, have made defects in collagen per se and collagen-based tissues primary targets for developing regenerative medicine strategies. Consequently, collagen and collagen-like materials have emerged as major substrates for tissue and/or chemical engineering. Traditionally, collagen has been isolated in soluble format from animal tissue and reconstituted into molded sponges or hydrogels. More recent techniques have employed the controlled deposition of nanofibers via electrospinning. However, the use of cells to deposit their own collagenous matrix is receiving increased attention, especially given the potential for autologous treatment and more physiological structural configurations. The recent popularization of detergent based "decellularization" of complete tissues/organs, which leaves behind a collagen-containing extracellular matrix that was secreted by the original resident cells, opens the possibility that cells themselves could be used to better generate or modulate physiological collagenous matrices. Therefore, this review will focus on recent patents related to the use of donor cells to realize collagen synthesis, enrichment, and repair, with the goal of clinical application.