Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University, Georgia Institute of Technology, Atlanta, GA 30332-0363, USA.
Spine J. 2012 Mar;12(3):265-72. doi: 10.1016/j.spinee.2012.02.002. Epub 2012 Mar 15.
Multiple biomaterials are clinically available to spine surgeons for performing interbody fusion. Poly-ether-ether-ketone (PEEK) is used frequently for lumbar spine interbody fusion, but alternative materials are also used, including titanium (Ti) alloys. Previously, we showed that osteoblasts exhibit a more differentiated phenotype when grown on machined or grit-blasted titanium aluminum vanadium (Ti6Al4V) alloys with micron-scale roughened surfaces than when grown on smoother Ti6Al4V surfaces or on tissue culture polystyrene (TCPS). We hypothesized that osteoblasts cultured on rough Ti alloy substrates would present a more mature osteoblast phenotype than cells cultured on PEEK, suggesting that textured Ti6Al4V implants may provide a more osteogenic surface for interbody fusion devices.
The aim of the present study was to compare osteoblast response to smooth Ti6Al4V (sTiAlV) and roughened Ti6Al4V (rTiAlV) with their response to PEEK with respect to differentiation and production of factors associated with osteogenesis.
This in vitro study compared the phenotype of human MG63 osteoblast-like cells cultured on PEEK, sTiAlV, or rTiAlV surfaces and their production of bone morphogenetic proteins (BMPs).
Surface properties of PEEK, sTiAlV, and rTiAlV discs were determined. Human MG63 cells were grown on TCPS and the discs. Confluent cultures were harvested, and cell number, alkaline phosphatase-specific activity, and osteocalcin were measured as indicators of osteoblast maturation. Expression of messenger RNA (mRNA) for BMP2 and BMP4 was measured by real-time polymerase chain reaction. Levels of BMP2, BMP4, and BMP7 proteins were also measured in the conditioned media of the cell cultures.
Although roughness measurements for sTiAlV (S(a)=0.09±0.01), PEEK (S(a)=0.43±0.07), and rTiAlV (S(a)=1.81±0.51) varied, substrates had similar contact angles, indicating comparable wettability. Cell morphology differed depending on the surface. Cells cultured on Ti6Al4V had lower cell number and increased alkaline phosphatase specific activity, osteocalcin, BMP2, BMP4, and BMP7 levels in comparison to PEEK. In particular, roughness significantly increased the mRNA levels of BMP2 and BMP4 and secreted levels of BMP4.
These data demonstrate that rTiAlV substrates increase osteoblast maturation and produce an osteogenic environment that contains BMP2, BMP4, and BMP7. The results show that modifying surface structure is sufficient to create an osteogenic environment without addition of exogenous factors, which may induce better and faster bone during interbody fusion.
脊柱外科医生可使用多种生物材料进行椎间融合。聚醚醚酮（PEEK）常用于腰椎椎间融合，但也使用其他材料，包括钛（Ti）合金。先前，我们发现与光滑 Ti6Al4V 表面或组织培养聚苯乙烯（TCPS）相比，在具有微米级粗糙度的机加工或喷丸处理的钛铝合金钒（Ti6Al4V）合金上生长的成骨细胞表现出更分化的表型。我们假设在粗糙 Ti 合金基底上培养的成骨细胞比在 PEEK 上培养的细胞表现出更成熟的成骨细胞表型，这表明纹理化 Ti6Al4V 植入物可为椎间融合装置提供更具成骨性的表面。
本研究的目的是比较光滑 Ti6Al4V（sTiAlV）和粗糙 Ti6Al4V（rTiAlV）与 PEEK 对成骨细胞分化和产生与成骨相关因子的反应，以评估它们的成骨反应。
本体外研究比较了在 PEEK、sTiAlV 或 rTiAlV 表面培养的人 MG63 成骨样细胞的表型及其骨形态发生蛋白（BMPs）的产生。
测定了 PEEK、sTiAlV 和 rTiAlV 盘的表面特性。将人 MG63 细胞种植在 TCPS 和培养皿上。收获汇合培养物，测量细胞数量、碱性磷酸酶特异性活性和骨钙素，以作为成骨细胞成熟的指标。通过实时聚合酶链反应测量 BMP2 和 BMP4 的信使 RNA（mRNA）表达。还测量了细胞培养物条件培养基中的 BMP2、BMP4 和 BMP7 蛋白的水平。
尽管 sTiAlV（S（a）=0.09±0.01）、PEEK（S（a）=0.43±0.07）和 rTiAlV（S（a）=1.81±0.51）的粗糙度测量值有所不同，但基底的接触角相似，表明润湿性相当。细胞形态因表面而异。与 PEEK 相比，在 Ti6Al4V 上培养的细胞数量较少，碱性磷酸酶特异性活性、骨钙素、BMP2、BMP4 和 BMP7 水平升高。特别是粗糙度显著增加了 BMP2 和 BMP4 的 mRNA 水平和 BMP4 的分泌水平。
这些数据表明 rTiAlV 基底可增加成骨细胞成熟并产生含有 BMP2、BMP4 和 BMP7 的成骨环境。结果表明，通过改变表面结构可以在不添加外源性因子的情况下创造出成骨环境，这可能在椎间融合过程中诱导更好、更快的骨形成。
