Expression and distribution of Cre recombinase in chondrocyte-specific Cre transgenic mice

Objective:To further investigate the temporal and spatial distribution of the Cre recombinase in Col2a1-Cre transgenic mouse. Methods: The chondrocyte-specific Cre transgenic mice were bred with ROSA26 reporter mice. The mice carrying both Cre and ROSA26 transgenes were obtained. The activity of Cre recombinase was observed by LacZ staining in the double transgenic mice. Results: LacZ staining showed that Cre recombinase activity was observed during the period of mesenchymal cell condensation. At E13.5, the expression of Cre recombinase was correlated with the expression of collagen Ⅱ in the forelimb, hindlimb, vertebra, and Meckel′s cartilage. In the neonates, LacZ expression was detected in all cartilaginous tissues which formed through the endochondral ossification. In addition, the tibia sections of neonates showed that growth plate chondrocytes, perichondrium cells and osteoblasts adjacent to growth plate were positive for lacZ staining. Conclusion: All these data indicated that the chondrocyte-specific Cre transgenic mice specifically expressed the Cre recombinase in the cartilage tissues, and could serve as useful tool for generating chondrocyte-specific gene-knockout mice.