Kapur S P, Reddi A H
Differentiation. 1986;32(3):252-9. doi: 10.1111/j.1432-0436.1986.tb00581.x.
Demineralized bone matrix (DBM) induces development of bone in vivo via the endochondral mode of development. Early events in this inductive process involve the appearance of mesenchymal cells (day 3) followed by chondrogenic differentiation (day 7) after subcutaneous implantation of DBM. In this investigation the chondrogenic potential in vitro of day 3 and day 4 mesenchymal cells from a DBM-induced implant has been explored. Immunofluorescent examination of day 3 cell cultures maintained for 4 days revealed the presence of type II collagen and cartilage-specific proteoglycans only in spherical or polyhedral cells. Micromass cultures and agarose suspension cultures showed toluidine-blue metachromasia in only a small population of cells. Biochemical estimation of 35SO4-labeled proteoglycans from suspension cultures of day 3 and day 4 cells maintained for 3 days indicated the presence of 29% and 38% large cartilage-specific proteoglycans, respectively. Addition of bone-inductive guanidine extract of DBM to the cultures did not significantly increase the percentage of large proteoglycans. These observations suggest that day 3 and day 4 cells can undergo chondrogenic differentiation in vitro without the continued presence of the bone-inductive guanidine extract. The presence of guanidine extract in cultures did not enhance chondrogenic expression or promote the recruitment of mesenchymal cells and their transformation to the chondrogenic phenotype.
脱矿骨基质（DBM）通过软骨内发育模式在体内诱导骨的形成。在皮下植入DBM后，这一诱导过程的早期事件包括间充质细胞的出现（第3天），随后是软骨形成分化（第7天）。在本研究中，对来自DBM诱导植入物的第3天和第4天的间充质细胞的体外软骨形成潜能进行了探索。对维持4天的第3天细胞培养物进行免疫荧光检查发现，仅在球形或多面体细胞中存在II型胶原蛋白和软骨特异性蛋白聚糖。微团培养和琼脂糖悬浮培养显示，只有一小部分细胞出现甲苯胺蓝异染性。对维持3天的第3天和第4天细胞的悬浮培养物中35SO4标记的蛋白聚糖进行生化评估表明，分别有29%和38%的大软骨特异性蛋白聚糖。向培养物中添加DBM的骨诱导胍提取物并没有显著增加大蛋白聚糖的百分比。这些观察结果表明，第3天和第4天的细胞在体外可以在没有骨诱导胍提取物持续存在的情况下进行软骨形成分化。培养物中胍提取物的存在并没有增强软骨形成表达，也没有促进间充质细胞的募集及其向软骨形成表型的转化。
