de Pollak C, Arnaud E, Renier D, Marie P J
INSERM Unité 349, Lariboisière Hospital, Paris, France.
J Cell Biochem. 1997 Jan;64(1):128-39.
We have determined the age-related changes in the growth characteristics and expression of the osteoblast phenotype in human calvaria osteoblastic cells in relation with histologic indices of bone formation during postnatal calvaria osteogenesis. Histomorphometric analysis of normal calvaria samples obtained from 36 children, aged 3 to 18 months, showed an age-related decrease in the extent of bone surface covered with osteoblasts and newly synthesized collagen, demonstrating a progressive decline in bone formation during postnatal calvaria osteogenesis. Immunohistochemical analysis showed expression of type I collagen, bone sialoprotein, and osteonectin in the matrix and osteoblasts, with no apparent age-related change during postnatal calvaria osteogenesis. Cells isolated from human calvaria displayed characteristics of the osteoblast phenotype including alkaline phosphatase (ALP) activity, osteocalcin (OC) production, expression of bone matrix proteins, and responsiveness to calciotropic hormones. The growth of human calvaria osteoblastic cells was high at 3 months of age and decreased with age, as assessed by (3H)-thymidine incorporation into DNA. Thus, the age-related decrease in bone formation is associated with a decline in osteoblastic cell proliferation during human calvaria osteogenesis. In contrast, ALP activity and OC production increased with age in basal conditions and in response to 1,25(OH)2 vitamin D3, suggesting a reciprocal relationship between cell growth and expression of phenotypic markers during human postnatal osteogenesis. Finally, we found that human calvaria osteoblastic cells isolated from young individuals with high bone formation activity in vivo and high growth potential in vitro had the ability to form calcified nodular bone-like structures in vitro in the presence of ascorbic acid and beta-glycerophosphate, providing a new model to study human osteogenesis in vitro.
我们已经确定了人颅骨成骨细胞生长特性和成骨细胞表型表达与出生后颅骨骨生成过程中骨形成组织学指标相关的年龄相关变化。对从36名3至18个月大儿童获取的正常颅骨样本进行组织形态计量学分析，结果显示覆盖有成骨细胞和新合成胶原蛋白的骨表面范围随年龄增长而减少，表明出生后颅骨骨生成过程中骨形成逐渐下降。免疫组织化学分析显示，在出生后颅骨骨生成过程中，基质和成骨细胞中I型胶原蛋白、骨唾液蛋白和骨连接蛋白的表达没有明显的年龄相关变化。从人颅骨分离的细胞表现出成骨细胞表型特征，包括碱性磷酸酶（ALP）活性、骨钙素（OC）产生、骨基质蛋白表达以及对钙调节激素的反应性。通过将（3H）-胸腺嘧啶掺入DNA评估，人颅骨成骨细胞在3个月大时生长旺盛，随后随年龄增长而下降。因此，在人颅骨骨生成过程中，与年龄相关的骨形成减少与成骨细胞增殖下降有关。相比之下，在基础条件下以及对1,25（OH）2维生素D3反应时，ALP活性和OC产生随年龄增加，表明在人出生后骨生成过程中细胞生长与表型标志物表达之间存在相互关系。最后，我们发现从体内具有高骨形成活性且体外具有高生长潜力的年轻个体分离的人颅骨成骨细胞，在存在抗坏血酸和β-甘油磷酸的情况下，能够在体外形成钙化结节状骨样结构，为体外研究人骨生成提供了一个新模型。
