Toquet J, Rohanizadeh R, Guicheux J, Couillaud S, Passuti N, Daculsi G, Heymann D
UPRES EA 2159, Centre de Recherche sur les Tissus Calcifiés et les Biomatériaux, Faculté de Chirurgie Dentaire, 1 place A. Ricordeau, 44042 Nantes, Cedex 01, France.
J Biomed Mater Res. 1999 Jan;44(1):98-108. doi: 10.1002/(sici)1097-4636(199901)44:1<98::aid-jbm11>3.0.co;2-p.
Calcium phosphate ceramics are synthetic bone substitutes that promote bone formation by osteoconduction. However, they have shown an osteogenic potential in vivo in animal models when associated with bone marrow cells. In order to develop an osteogenic human "hybrid material," we studied the in vitro osteogenic potential of human bone marrow cells cultured on macroporous biphasic calcium phosphate (BCP) pellets in the presence of dexamethasone with or without 1alpha,25 dihydroxyvitamin D3. We were examining, in particular, their mesenchymal stem cell proliferation and hematopoietic potential. Osteogenic differentiation was evaluated in terms of alkaline phosphatase activity and immunological characterization of the extracellular matrix formed by these cells. The specimens were observed by scanning and transmission electron microscopy. Human mesenchymal stem cells proliferated on macroporous BCP ceramic, with a doubling time delayed at the beginning of the culture as compared to the cultures realized on plastic. These cells maintained a hematopoietic activity identical to that of cultures performed in plastic wells. The proliferating mesenchymal stem cells expressed an osteoblastic phenotype, as shown by alkaline phosphatase activity and the synthesis in ceramic macropores of an extracellular matrix composed of fibronectin, osteocalcin, and collagen I (but not collagen III). In addition, numerous microcrystals of apatite precipitated on the extracellular matrix, producing a mineralized fibrillar network within the ceramic not observed with cell cultures realized on plastic. These results demonstrate that human mesenchymal stem cells cultured on macroporous BCP ceramic express and conserve their osteoblastic phenotype even after one month of culture and that these osteogenic cells are able to form new bone matrix in a BCP ceramic in vitro.
磷酸钙陶瓷是通过骨传导促进骨形成的合成骨替代物。然而，当与骨髓细胞结合时，它们在动物模型体内已显示出成骨潜力。为了开发一种具有成骨作用的人类“混合材料”，我们研究了在存在或不存在1α,25二羟基维生素D3的地塞米松条件下，培养在大孔双相磷酸钙（BCP）微丸上的人类骨髓细胞的体外成骨潜力。我们特别研究了它们的间充质干细胞增殖和造血潜力。根据碱性磷酸酶活性以及这些细胞形成的细胞外基质的免疫学特征来评估成骨分化。通过扫描电子显微镜和透射电子显微镜观察标本。人类间充质干细胞在大孔BCP陶瓷上增殖，与在塑料上培养相比，培养开始时倍增时间延迟。这些细胞保持与在塑料孔中培养相同的造血活性。增殖的间充质干细胞表达成骨细胞表型，如碱性磷酸酶活性以及在陶瓷大孔中合成由纤连蛋白、骨钙素和I型胶原（而非III型胶原）组成的细胞外基质所示。此外，大量磷灰石微晶沉淀在细胞外基质上，在陶瓷内产生了在塑料上进行的细胞培养中未观察到的矿化纤维网络。这些结果表明，培养在大孔BCP陶瓷上的人类间充质干细胞即使在培养一个月后仍表达并保留其成骨细胞表型，并且这些成骨细胞能够在体外的BCP陶瓷中形成新的骨基质。
