Shah Furqan A, Stenlund Patrik, Martinelli Anna, Thomsen Peter, Palmquist Anders
Department of Biomaterials, Sahlgrenska Academy at University of Gothenburg, Göteborg, Sweden.
BIOMATCELL VINN Excellence Centre of Biomaterials and Cell Therapy, Göteborg, Sweden.
J Mater Sci Mater Med. 2016 Nov;27(11):167. doi: 10.1007/s10856-016-5779-1. Epub 2016 Oct 3.
The osteocyte network, through the numerous dendritic processes of osteocytes, is responsible for sensing mechanical loading and orchestrates adaptive bone remodelling by communicating with both the osteoclasts and the osteoblasts. The osteocyte network in the vicinity of implant surfaces provides insight into the bone healing process around metallic implants. Here, we investigate whether osteocytes are able to make an intimate contact with topologically modified, but micrometre smooth (S < 0.5 µm) implant surfaces, and if sub-micron topography alters the composition of the interfacial tissue. Screw shaped, commercially pure (cp-Ti) titanium implants with (i) machined (S = ~0.2 µm), and (ii) two-step acid-etched (HF/HNO and HSO/HCl; S = ~0.5 µm) surfaces were inserted in Sprague Dawley rat tibia and followed for 28 days. Both surfaces showed similar bone area, while the bone-implant contact was 73 % higher for the acid-etched surface. By resin cast etching, osteocytes were observed to maintain a direct intimate contact with the acid-etched surface. Although well mineralised, the interfacial tissue showed lower Ca/P and apatite-to-collagen ratios at the acid-etched surface, while mineral crystallinity and the carbonate-to-phosphate ratios were comparable for both implant surfaces. The interfacial tissue composition may therefore vary with changes in implant surface topography, independently of the amount of bone formed. Implant surfaces that influence bone to have higher amounts of organic matrix without affecting the crystallinity or the carbonate content of the mineral phase presumably result in a more resilient interfacial tissue, better able to resist crack development during functional loading than densely mineralised bone.
骨细胞网络通过骨细胞众多的树突状突起，负责感知机械负荷，并通过与破骨细胞和成骨细胞进行通讯来协调适应性骨重塑。植入物表面附近的骨细胞网络为了解金属植入物周围的骨愈合过程提供了线索。在此，我们研究骨细胞是否能够与拓扑结构改变但微米级光滑（S < 0.5 µm）的植入物表面进行紧密接触，以及亚微米级形貌是否会改变界面组织的组成。将具有（i）机械加工表面（S = ~0.2 µm）和（ii）两步酸蚀表面（HF/HNO和HSO/HCl；S = ~0.5 µm）的螺旋形商业纯（cp-Ti）钛植入物插入Sprague Dawley大鼠胫骨中，并观察28天。两种表面的骨面积相似，但酸蚀表面的骨-植入物接触率高73%。通过树脂铸型蚀刻观察到，骨细胞与酸蚀表面保持直接紧密接触。尽管界面组织矿化良好，但在酸蚀表面，其钙/磷和磷灰石与胶原蛋白的比例较低，而两种植入物表面的矿物结晶度和碳酸盐与磷酸盐的比例相当。因此，界面组织组成可能会随植入物表面形貌的变化而变化，与形成的骨量无关。影响骨形成更多有机基质而不影响矿相结晶度或碳酸盐含量的植入物表面，可能会导致形成更具弹性的界面组织，在功能负荷期间比致密矿化的骨更能抵抗裂纹发展。
