Alpha 5 Integrin Mediates Osteoarthritic Changes in Mouse Knee Joints.

Osteoarthritis (OA) is one of most common skeletal disorders and can affect synovial joints such as knee and ankle joints. α5 integrin, a major fibronectin receptor, is expressed in articular cartilage and has been demonstrated to play roles in synovial joint development and in the regulation of chondrocyte survival and matrix degradation in articular cartilage. We hypothesized that α5 integrin signaling is involved in pathogenesis of OA.

Tendon progenitor cells in injured tendons have strong chondrogenic potential: the CD105-negative subpopulation induces chondrogenic degeneration.

To study the cellular mechanism of the tendon repair process, we used a mouse Achilles tendon injury model to focus on the cells recruited to the injured site. The cells isolated from injured tendon 1 week after the surgery and uninjured tendons contained the connective tissue progenitor populations as determined by colony-forming capacity, cell surface markers, and multipotency. When the injured tendon-derived progenitor cells (inTPCs) were transplanted into injured Achilles tendons, they were not only integrated in the regenerating area expressing tenogenic phenotype but also trans-differentiated into chondrogenic cells in the degenerative lesion that underwent ectopic endochondral ossification.

Distribution of slow-cycling cells in epiphyseal cartilage and requirement of β-catenin signaling for their maintenance in growth plate.

Slow proliferation is one of the characteristics of stem cells. We examined the presence, distribution, and regulation of slow-cycling cells in the developing and growing skeleton using a pulse-chase method with a new nucleoside derivative, 5-ethynyl-2'-deoxyuridine (EdU). C57BL/6 mice received daily intraperitoneal injections of EdU from postnatal day 4 to day 7.

Loss of β-catenin induces multifocal periosteal chondroma-like masses in mice.

Osteochondromas and enchondromas are the most common tumors affecting the skeleton. Osteochondromas can occur as multiple lesions, such as those in patients with hereditary multiple exostoses. Unexpectedly, while studying the role of β-catenin in cartilage development, we found that its conditional deletion induces ectopic chondroma-like cartilage formation in mice.