CCN2 overexpression causes enhanced type II collagen and proteoglycan deposition, enhanced chondrocyte proliferation and shortening of the hypertrophic cartilage zone.

<p>Tibiae from P1 littermates were stained with safranin-O for proteoglycans (A, left) and with anti-type II collagen antibody (B, left). Whole littermates were analyzed and the color intensity of 3 different wt or tg individuals was measured densitometrically; and the mean values are presented. (A, right; and B, right). *: p<0.005. Typical images from tg and wt littermates are shown. (C, left) Comparison of hypertrophic cartilage zone of CCN2 transgenic littermates. Tibiae were stained with type X collagen antibody. (C, right) The hypertrophic zone of tg cartilage appeared shorter compared with that of the wt cartilage. (D) Immunohistochemical analysis of proliferative cell nuclear antigen (PCNA) in tibiae of <i>ccn2</i> tg embryos at E19.5. Proliferative cells were observed in the whole epiphyseal cartilage of tg animals, whereas they were restricted to the proliferative zone of the wt littermates. The number of PCNA-positive cells inside of the boxed area was counted in 5 fields of 3 comparable wt and tg sections. Mean values indicate enhanced chondrocyte proliferation in the tg cartilage (graph at the lower right). *: p<0. 05.