Targeting cartilage EGFR pathway for osteoarthritis treatment.

Enhancing EGFR to offset osteoarthritis: Cartilage degeneration in osteoarthritis causes pain and limits mobility. Wei et al. investigated epidermal growth factor receptor (EGFR) signaling as a potential targeted disease-modifying treatment, because EGFR activity is linked to cartilage homeostasis. Cartilage-specific genetic overactivation of EGFR resulted in enlarged cartilage, an expanded tissue progenitor cell population, and resistance to surgically induced osteoarthritis in mice. Treating mice with transforming growth factor–α (an EGFR ligand) conjugated to nanoparticles via intra-articular injections protected against cartilage degeneration and attenuated pain in an osteoarthritis model. Results show how targeting EGFR signaling could potentially treat osteoarthritis. Osteoarthritis (OA) is a widespread joint disease for which there are no disease-modifying treatments. Previously, we found that mice with cartilage-specific epidermal growth factor receptor (EGFR) deficiency developed accelerated knee OA. To test whether the EGFR pathway can be targeted as a potential OA therapy, we constructed two cartilage-specific EGFR overactivation models in mice by overexpressing heparin binding EGF-like growth factor (HBEGF), an EGFR ligand. Compared to wild type, Col2-Cre HBEGF-overexpressing mice had persistently enlarged articular cartilage from adolescence, due to an expanded pool of chondroprogenitors with elevated proliferation ability, survival rate, and lubricant production. Adult Col2-Cre HBEGF-overexpressing mice and Aggrecan-CreER HBEGF-overexpressing mice were resistant to cartilage degeneration and other signs of OA after surgical destabilization of the medial meniscus (DMM). Treating mice with gefitinib, an EGFR inhibitor, abolished the protective action against OA in HBEGF-overexpressing mice. Polymeric micellar nanoparticles (NPs) conjugated with transforming growth factor–α (TGFα), a potent EGFR ligand, were stable and nontoxic and had long joint retention, high cartilage uptake, and penetration capabilities. Intra-articular delivery of TGFα-NPs effectively attenuated surgery-induced OA cartilage degeneration, subchondral bone plate sclerosis, and joint pain. Genetic or pharmacologic activation of EGFR revealed no obvious side effects in knee joints and major vital organs in mice. Together, our studies demonstrate the feasibility of using nanotechnology to target EGFR signaling for OA treatment. [ABSTRACT FROM AUTHOR]