The cartilage degeneration in a growing rat experimental model of developmental trochlear dysplasia is associated with activation of PI3K/AKT signal pathway

Abstract

Background As one of the lower extremity deformities in human, trochlear dysplasia is a commonly encountered disease. However, the molecular mechanism of cartilage degeneration in trochlear dysplasia is indefinite yet. It was apparent to all that PI3K/AKT signal pathway is extremely significant in regulating the pathophysiological process of cartilage degeneration. The purpose of this research is to discuss the correlation between PI3K/AKT signal pathway and trochlear dysplasia cartilage degeneration. Materials and methods 120 female Sprague-Dawley rats at 4 weeks of age were separate into control group and experimental group randomly. The distal femurs were isolated from the experimental and unsurgeried control group at the point of the 4, 8, 12 weeks, correspondingly. Micro-CT and histological examination were carried out to investigate the anatomical structure and cartilage changes of the trochlear. Subsequently, the expression of PI3K/AKT, TGFβ1 and ADAMTS-4 in cartilage were investigated by immunohistochemistry and quantitative real-time polymerase chain reaction (qRT-PCR). Results In the experimental group, the trochlear dysplasia model was successfully established at 8 weeks after surgery. Moreover, the cartilage degeneration was found from 8 weeks, with continued higher protein and mRNA expression of PI3K/AKT, TGFβ1 and ADAMTS-4 compared with the control group. Conclusions This research suggested that patellar instability may lead to trochlear dysplasia in growing rats. Moreover, trochlear dysplasia was probably one of the causes of patellofemoral osteoarthritis and the cartilage degeneration in trochlear dysplasia might be associate with activation of PI3K/AKT signal pathway. However, more research was required to clarify the underlying mechanisms.