Biomedical Engineering Department, Northwestern University, Evanston, IL 60208, USA.
Acta Biomater. 2011 Nov;7(11):4057-63. doi: 10.1016/j.actbio.2011.07.001. Epub 2011 Jul 13.
The incorporation of nanoscale hydroxyapatite (HA) into biodegradable polymers can potentially mimic the native structure of bone and influence the mechanical properties and the extent of bioactivity. In this study nanocomposites of poly(1,8-octanediol-co-citrate) (POC) containing 40, 50, and 60 wt.% HA (POC-HA) were fabricated and characterized. Nanocomposite hydrophilicity and the degradation properties in vitro were evaluated via contact angle measurements, scanning electron microscopy (SEM), and mass loss measurements. Human mesenchymal stem cells (hMSC) were cultured on POC-HA nanocomposites in both growth and osteogenic media. Cell proliferation, alkaline phosphatase activity, and osteocalcin were measured. The equilibrium water in air contact angles confirmed all of the nanocomposites to be hydrophilic (23.4 ± 8.1°, 27 ± 9.1°, and 27.7 ± 3.5° for 40, 50, and 60 wt.% HA, respectively). Over a period of 26 weeks the degradation rate increased with decreasing HA content and pore formation was evident for POC-HA containing 40 wt.% HA, whereas POC with 50 and 60 wt.% HA lacked pores (mass loss at 26 weeks for 40, 50, and 60 wt.% HA, 27.4 ± 1.6%, 17.7 ± 1.6%, and 6.3 ± 2.6%, respectively). hMSC adhered and proliferated well on all composites, confirming biocompatibility for at least 21 days. An increase in adhesion and proliferation was found with increasing HA nanoparticle content (ng DNA at day 21 for 40, 50, and 60 wt.% HA, 130.4 ± 49.4, 184.4 ± 86.4, 314.1 ± 92.3). Alkaline phosphatase activity and osteocalcin concentration correlated with HA content (alkaline phosphate activity in expansion medium and osteogenic medium for 40, 50, and 60 wt.% HA, 256.1 ± 71.8%, 304.0 ± 128.7%, and 500.2 ± 89.9%, and 358.4 ± 124.1%, 653.7 ± 216.5%, and 814.4 ± 68.8%, respectively; osteocalcin concentration in expansion medium and osteogenic medium for 40, 50, and 60 wt.% HA, 236.9 ± 7.8%, 253.0 ± 7.5%, and 285.2 ± 11.4%, and 265.8 ± 15.0%, 288.3 ± 17.9%, and 717.3 ± 38.7%, respectively). This study provides insight into how the HA nanoparticle content can modulate the cell compatibility and physical properties of POC-HA nanocomposites.
将纳米级羟基磷灰石（HA）掺入可生物降解聚合物中，可以模拟骨的天然结构并影响机械性能和生物活性程度。本研究制备了含有 40、50 和 60wt.%HA 的聚（1,8-辛二醇-柠檬酸酯）（POC）纳米复合材料（POC-HA）并对其进行了表征。通过接触角测量、扫描电子显微镜（SEM）和质量损失测量来评估纳米复合材料的亲水性和体外降解性能。将人骨髓间充质干细胞（hMSC）在生长和成骨培养基中分别培养在 POC-HA 纳米复合材料上。测量细胞增殖、碱性磷酸酶活性和骨钙素。空气中的平衡水接触角证实所有纳米复合材料均具有亲水性（40wt.%HA 时为 23.4±8.1°、50wt.%HA 时为 27±9.1°、60wt.%HA 时为 27.7±3.5°）。在 26 周的时间内，降解速率随 HA 含量的降低而增加，并且在含有 40wt.%HA 的 POC-HA 中可以看到孔形成，而含有 50 和 60wt.%HA 的 POC 则没有孔（26 周时的质量损失，40wt.%HA、50wt.%HA 和 60wt.%HA 分别为 27.4±1.6%、17.7±1.6%和 6.3±2.6%）。hMSC 很好地黏附和增殖于所有复合材料上，证实了至少 21 天的生物相容性。随着 HA 纳米颗粒含量的增加，黏附和增殖均增加（第 21 天 40wt.%HA、50wt.%HA 和 60wt.%HA 的 DNA 含量分别为 130.4±49.4ng、184.4±86.4ng 和 314.1±92.3ng）。碱性磷酸酶活性和骨钙素浓度与 HA 含量相关（40wt.%HA、50wt.%HA 和 60wt.%HA 时碱性磷酸酶活性在扩展培养基和成骨培养基中分别为 256.1±71.8%、304.0±128.7%和 500.2±89.9%，骨钙素浓度在扩展培养基和成骨培养基中分别为 358.4±124.1%、653.7±216.5%和 814.4±68.8%）。本研究深入了解了 HA 纳米颗粒含量如何调节 POC-HA 纳米复合材料的细胞相容性和物理性能。
