Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, 1304 West Green Street, Urbana, IL 61801, USA.
Acta Biomater. 2010 Aug;6(8):3283-91. doi: 10.1016/j.actbio.2010.02.026. Epub 2010 Feb 20.
It is well established that scaffolds for applications in bone tissue engineering require interconnected pores on the order of 100 microm for bone in growth and nutrient and waste transport. As a result, most studies have focused on scaffold macroporosity (>100 microm). More recently researchers have investigated the role of microporosity in calcium phosphate -based scaffolds. Osteointegration into macropores improves when scaffold rods or struts contain micropores, typically defined as pores less than approximately 50 microm. We recently demonstrated multiscale osteointegration, or growth into both macropores and intra-red micropores (<10 microm), of biphasic calcium phosphate (BCP) scaffolds. The combined effect of BMP-2, a potent osteoinductive growth factor, and multiscale porosity has yet to be investigated. In this study we implanted BCP scaffolds into porcine mandibular defects for 3, 6, 12 and 24 weeks and evaluated the effect of BMP-2 on multiscale osteointegration. The results showed that given this in vivo model BMP-2 influences osteointegration at the microscale, but not at the macroscale, but not at the macroscale. Cell density was higher in the rod micropores for scaffolds containing BMP-2 compared with controls at all time points, but BMP-2 was not required for bone formation in micropores. In contrast, there was essentially no difference in the fraction of bone in macropores for scaffolds with BMP-2 compared with controls. Additionally, bone in macropores seemed to have reached steady-state by 3 weeks. Multiscale osteointegration results in bone-scaffold composites that are fully osteointegrated, with no 'dead space'. These composites are likely to contain a continuous cell network as well as the potential for enhanced load transfer and improved mechanical properties.
已经证实，应用于骨组织工程的支架需要具有 100 微米左右的连通孔，以促进骨生长和营养物质及废物的传输。因此，大多数研究都集中在支架的大孔结构（>100 微米）上。最近，研究人员研究了微孔在基于磷酸钙的支架中的作用。当支架棒或支柱包含微孔时，骨整合到大孔中会得到改善，微孔通常定义为小于约 50 微米的孔。我们最近证明了双相磷酸钙（BCP）支架的多尺度骨整合，即同时向大孔和内微孔（<10 微米）生长。骨形态发生蛋白-2（一种有效的成骨诱导生长因子）和多尺度孔隙率的综合作用尚未得到研究。在这项研究中，我们将 BCP 支架植入猪下颌骨缺损中 3、6、12 和 24 周，并评估了 BMP-2 对多尺度骨整合的影响。结果表明，在这种体内模型中，BMP-2 影响微尺度的骨整合，但不影响大尺度的骨整合，但不影响大尺度的骨整合。在所有时间点，含有 BMP-2 的支架的棒状微孔中的细胞密度都高于对照组，但微孔中的骨形成不需要 BMP-2。相比之下，BMP-2 组和对照组的大孔中骨的比例基本上没有差异。此外，大孔中的骨似乎在 3 周时已达到稳定状态。多尺度骨整合导致骨-支架复合材料完全骨整合，没有“死腔”。这些复合材料可能包含连续的细胞网络，以及增强的负载传递和改善的机械性能的潜力。
