三种多孔磷酸钙骨水泥体外研究比较

Comparative Studies of Three Kinds of Macroporous Calcium Phosphate Cements in Vitro

目的：探讨以不同方法制备的三种多孔磷酸钙骨水泥（Calcium phosphate cement, CPC）的理化特性、生物相容性及强度的差异.方法：将20wt%甘露醇（A组）、5wt%碳酸氢钠（B组）及5wt%明胶微球（C组）分别与CPC粉末混合固化制备多孔CPC.生理盐水浸泡1周、4周后,测定材料孔径率及抗压强度,电镜观察材料断面,X线衍射法检测CPC的转化情况.成骨细胞接种于各组CPC支架上,扫描电镜观察细胞形态;三组材料浸提液分别与成骨细胞共培养3 d,MTT法测定细胞增殖率,试剂盒检测碱性磷酸酶水平.结果：浸泡1周后C组孔径率稍低,4周后各组无明显差异;但两个时间点C组强度均最高.材料断面扫描A组孔径较大、连通性欠佳,B组孔径极不规则且分布不均匀,C组孔径规则、连通性好.1周后X线衍射显示三组均出现羟基磷灰石衍射峰;4周后C组羟基磷灰石衍射峰最强,磷酸四钙衍射峰最弱.成骨细胞在各组材料上生长良好,但C组细胞量最多,细胞增殖及碱性磷酸酶水平明显高于其他两组.结论：以明胶微球制备的多孔CPC具有较高的初始强度及较好的生物相容性,可作为非负重部位骨替代材料.

Objective：To compare the characteristics of three kinds of macroporous calcium phosphate cements （CPCs） prepared via different means in vitro. Methods：Three kinds of macroporous CPCs were devel- oped by mixing 20 wt % mannitol （ Group A） , 5 wt % sodium bicarbonate （ Group B）, and 5 wt% gelatin microsphere （Group C） , respectively with CPC powder. Then the three productions were soaked in sodium chlo- ride. At the ends of the first and fourth weeks, to detect their porosity and compressive strength, observe their cross-sections by scanning electron microscopy （ SEM ） and evaluate translation of CPCs by diffraction of X-ray （XRD）. After the osteoblasts had been seeded on the different macroporous CPCs for 2 days, their morphologies were observed under the SEM. When the osteoblasts had been cultured with the leaching liquor respectively from above mentioned three kinds of materials for 3 days, the cellular viability and levels of alkaline phosphatase （ALP） were measured by the MTT assay and alkaline phosphatase kit, respectively. Results：At the end of first week of soaking, the porosity in group C was lowest. However, there was no difference at the end of fourth week. The compressive strength in group C was strongest after soaking. The SEM images showed that： the pores in group A were largest but had poor connectivity; in group B were very irregular and displayed maldistribution; in group C were regular and had good connectivity. The XRD results showed that there was diffraction peak of hydroxyapatite （HAP） in all groups at the end of the first week after soaking. And at the end of fourth week af- ter soaking, the diffraction peak of HAP in group C was highest, and the peak of tetracalcium phosphate （TrcP） was lowest. The Osteoblasts exhibited normal morphologies on all macroporous CPCs, however, those in Group C proliferated and differentiated best compared to those in Groups B and C. Conclusions：The macroporous CPC developed by using gelatin microspheres possesses better biocompatibility and compressive strength, and it could serve for a good bone substitute under non-loaded circumstance.