Turhani Dritan, Weissenböck Martina, Stein Elisabeth, Wanschitz Felix, Ewers Rolf
Department of Cranio-Maxillofacial and Oral Surgery, Medical University of Vienna, Vienna, Austria.
J Oral Maxillofac Surg. 2007 Mar;65(3):485-93. doi: 10.1016/j.joms.2005.12.065.
Tissue engineering of bone entails the successful interplay between osteoinductive factors, osteogenic cells, their extracellular environment, and an osteoconductive biomaterial scaffold. Naturally produced ceramics, like hydroxyapatite (HA) calcified from red algae, are the most promising materials for use as scaffolds in this field. We hypothesized that extracellular matrix compartments and osteoinductive factors could further ameliorate the bioactivity of the scaffold.
Osteosarcoma cells with proven osteogenic phenotype (SaOS-2) were cultured onto type I collagen coated (Coll I/HA) and noncollagen coated HA granules (NC/HA) gained from red algae (C GRAFT/Algipore). Cells grown on tissue culture polystyrene dishes (TCPS) were used as controls. Second, SaOS-2 cells cultured on Coll I/HA, NC/HA, and TCPS were treated with recombinant human bone morphogenetic protein-2 (rhBMP-2) in different concentrations (10, 100, and 500 ng/mL). Non rhBMP-2-treated cultures were used as controls. Cultures of both experiments were grown under osteogenic differentiation conditions and after 24, 48, and 72 hours assays for cell viability, apoptosis, alkaline phosphatase activity (ALP), and osteocalcin (OC) secretion were done.
Coating of HA granules with type I collagen showed higher cell viability in rhBMP-2-treated and nontreated cells. Supplementation of cultured cells with exogenous rhBMP-2 showed a dose-dependent effect only in the TCPS group. No alterations of the apoptotic rate within 1 investigation group were found. Addition of rhBMP-2 did not significantly alter the specific OC secretion of cells grown on Coll I/HA and TCPS.
These in vitro findings show that in the initial period of cultivation and up to 72 hours, the coating of HA granules with collagen type I had positive effects on cell viability and osteoblastic characteristics of osteoblastic cells. In contrast, the supplementation with exogenous rhBMP-2 shows no dose-dependent effects. The combination of collagen type I and exogenous rhBMP-2 did not ameliorate the bioactivity of hydroxyapatite calcified from red algae in the initial period of cultivation.
骨组织工程需要骨诱导因子、成骨细胞、其细胞外环境和骨传导生物材料支架之间成功相互作用。天然产生的陶瓷，如从红藻钙化而来的羟基磷灰石（HA），是该领域用作支架的最有前景的材料。我们假设细胞外基质区室和骨诱导因子可以进一步改善支架的生物活性。
将具有成骨表型的骨肉瘤细胞（SaOS-2）培养在涂有I型胶原的（Coll I/HA）和未涂胶原的HA颗粒（NC/HA）上，这些颗粒取自红藻（C GRAFT/Algipore）。在组织培养聚苯乙烯培养皿（TCPS）上生长的细胞用作对照。其次，在Coll I/HA、NC/HA和TCPS上培养的SaOS-2细胞用不同浓度（10、100和500 ng/mL）的重组人骨形态发生蛋白-2（rhBMP-2）处理。未用rhBMP-2处理的培养物用作对照。两个实验的培养物均在成骨分化条件下生长，在24、48和72小时后进行细胞活力、凋亡、碱性磷酸酶活性（ALP）和骨钙素（OC）分泌的检测。
用I型胶原包被HA颗粒在rhBMP-2处理和未处理的细胞中均显示出更高的细胞活力。用外源性rhBMP-2补充培养细胞仅在TCPS组中显示出剂量依赖性效应。在一个研究组内未发现凋亡率的改变。添加rhBMP-2并未显著改变在Coll I/HA和TCPS上生长的细胞的特异性OC分泌。
这些体外研究结果表明，在培养初期直至72小时，用I型胶原包被HA颗粒对成骨细胞的细胞活力和成骨细胞特性具有积极影响。相比之下，补充外源性rhBMP-2未显示出剂量依赖性效应。在培养初期，I型胶原和外源性rhBMP-2的组合并未改善从红藻钙化而来的羟基磷灰石的生物活性。
