Cdkn2a Tracer Mice: A Novel Model to Study Cellular Senescence in Post-traumatic Osteoarthritis / 中国生物化学与分子生物学报

ABSTRACT

Osteoarthritis (OA) is one of the most common geriatric motor system diseases in the clinical practice. Aging, whose hallmark is cellular senescence, is an important factor leading to the occurrence and development of OA, but its exact role in the pathological development of OA is not completely clear. Studies have proved that targeting senescence can effectively treat aging-related diseases. In this study, the heterozygous mouse model of Cdkn2a-e (Luc-2A-tdTomato-2a-CreerT2-Wpre-PA)1 was established by the CRISPR/ Cas9 technique. The expression of Cdkn2a (p16, p16INK4a), a classical marker of senescence, can be traced in vivo in mice. We then utilized anterior cruciate ligament transection (ACLT) to induce OA in Cdkn2a mice, and we hope to verify the relationship between aging and the occurrence and development of OA and visualize aging changes during OA development through the mice model. In this study, 10-12 weeks old Cdkn2a mice were randomly divided into no surgery control group, sham operation group and ACLT group. OA model was constructed in mice by ACLT operation. After surgery for 4 weeks, animals were collected for fluorescence imaging detection in vivo, which showed that local fluorescence expression of Cdkn2a increased in knee joints of mice in the ACLT group four weeks after surgery (P < 0. 05) . The Safranin O-Fast Green Staining of mouse knee tissue sections showed degeneration of the knee cartilage in the ACLT group at 4 weeks after surgery (P < 0. 05) . Immunohistochemical staining of Cdkn2a was performed on the knee tissue of mice. Compared with the other two groups, Cdkn2a staining on the cartilage surface of the knee tissue of mice in the ACLT group was deeper. The results showed that the OA model induced by surgery showed local aging, which further verified the relationship between aging and OA. At the same time, the Cdkn2a tracer mouse model can reflect the aging progress of mice in vivo, with combination of imaging examinations, so that the occurrence and progress of the relationship between aging and OA can be observed in real time. This heterozygous mouse model of Cdkn2a-e(Luc-2A-tdTomato-2a-CreerT2-Wpre-PA) 1 is not only useful for mechanism research of aging and OA diseases, but also beneficial for finding more potential therapy targets to OA and aging.