Department of Chemical Engineering, Ecole Polytechnique de Montreal, PO Box 6079, Succ Centre-Ville, Montreal, Quebec, Canada.
Osteoarthritis Cartilage. 2011 Jan;19(1):136-44. doi: 10.1016/j.joca.2010.10.026. Epub 2010 Oct 31.
Subchondral drilling initiates a cartilage repair response involving formation of chondrogenic foci in the subchondral compartment. The purpose of this study was to structurally characterize these sites of chondrogenesis and to investigate the effects of chitosan-glycerol phosphate (GP)/blood implants on their formation.
Thirty-two New Zealand White rabbits received bilateral cartilage defects bearing four subchondral drill holes. One knee per rabbit was treated by solidifying a chitosan-GP/blood implant over the defect. After 1-56 days of repair, chondrogenic foci were characterized by histostaining and immunostaining. Collagen fiber orientation was characterized by polarized light microscopy.
Glycosaminoglycan and collagen type II were present throughout the foci while the upper zone expressed collagen type I and the lower zone collagen type X. Large chondrogenic foci had a stratified structure with flatter cells closer to the articular surface, and round or hypertrophic chondrocytes deeper in the drill holes that showed signs of calcification after 3 weeks of repair in control defects. Markers for pre-hypertrophic chondrocytes (Patched) and for proliferation (Ki-67) were detected within foci. Some cells displayed a columnar arrangement where collagen was vertically oriented. For treated defects, chondrogenic foci appeared 1-3 weeks later, foci were nascent and mature rather than resorbing, and foci developed closer to the articular surface.
Chondrogenic foci bear some similarities to growth cartilage and can give rise to a repair tissue that has similar zonal stratification as articular cartilage. The temporal and spatial formation of chondrogenic foci can be modulated by cartilage repair therapies.
软骨下钻孔会引发软骨修复反应，在软骨下腔形成软骨发生焦点。本研究的目的是对这些软骨发生部位进行结构特征分析，并研究壳聚糖-甘油磷酸（GP）/血液植入物对其形成的影响。
32 只新西兰白兔双侧膝关节软骨缺损处钻 4 个软骨下孔。每只兔子的一条膝关节通过在缺损处凝固壳聚糖-GP/血液植入物进行处理。修复 1-56 天后，通过组织染色和免疫染色对软骨发生焦点进行特征分析。通过偏光显微镜对胶原纤维取向进行特征分析。
软骨发生焦点处存在糖胺聚糖和 II 型胶原，而上区表达 I 型胶原，下区表达 X 型胶原。大的软骨发生焦点具有分层结构，靠近关节表面的细胞更平坦，钻孔深处的圆形或肥大软骨细胞具有钙化迹象，在对照缺损中修复 3 周后可见。软骨发生焦点内检测到前肥大软骨细胞标志物（ patched ）和增殖标志物（ Ki-67 ）。一些细胞表现出垂直排列的胶原的柱状排列。对于治疗缺陷，软骨发生焦点出现的时间更早，焦点是新生的和成熟的，而不是吸收的，并且焦点更靠近关节表面形成。
软骨发生焦点与生长软骨有一些相似之处，可以产生具有与关节软骨相似的分层结构的修复组织。软骨修复疗法可以调节软骨发生焦点的时空形成。
