Department of Materials Science and Engineering, Gwangju Institute of Science and Technology, Republic of Korea.
Acta Biomater. 2011 Jan;7(1):244-57. doi: 10.1016/j.actbio.2010.08.017. Epub 2010 Aug 27.
Recently, the ligament-bone (LTB) junction has been emphasized for the effective transmission of mechanical force and the reduction in stress concentration between the soft ligament and hard bone tissue. The aim of this study was to regenerate an integrated LTB interface by inoculating LTB-relevant cells, isolated from fibrocartilage (FC) or ligament (LIG), separately into each designated region in a single porous cylindrical PLCL scaffold. An injectable, heparin-based hydrogel that has proved to be effective in the culture of chondrocytes as well as the sustained release of growth factor was employed to locally deliver fibrochondrocytes and osteoinductive bone morphogenetic protein-2 (BMP-2) into the FC region, to promote FC regeneration. In in vitro experiments the hydrogel-combined FC systems produced significantly larger amounts of calcium and glycosaminoglycans (GAGs), but less collagen and DNA than FC samples without the hydrogel and all LIG samples. After in vivo subcutaneous implantation in mice for 8 weeks the secreted calcium and GAG contents of the hydrogel-containing FC samples were superior or similar to those of the in vitro hydrogel-containing FC samples at 6 weeks. As a result of the enhanced production of calcium and GAG, the in vivo hydrogel-containing FC samples produced the highest compressive modulus among all samples. Histological and immunofluorescence analysis as well as elemental analysis also confirmed a denser and more homogeneous distribution of calcium, GAG, osteocalcin and neovascularization marker in the in vitro/in vivo hydrogel-containing FC systems than those without hydrogel. These results also show the beneficial effects of BMP-2 added using the hydrogel. In summary, the use of a heparin-based hydrogel for the local delivery of fibrochondrocytes and BMP-2 could accelerate the maturation and differentiation of LTB-specific FC tissues, and it was also possible to recreate the unique stratification of calcified FC and LIG tissues in a single porous PLCL scaffold in terms of both biochemical and biomechanical properties.
最近，韧带-骨（LTB）交界处已被强调，以有效传递机械力并减少软韧带和硬骨组织之间的应力集中。本研究的目的是通过将来自纤维软骨（FC）或韧带（LIG）的 LTB 相关细胞分别接种到单个多孔圆柱状 PLCL 支架的每个指定区域，来再生一个整合的 LTB 界面。一种可注射的、基于肝素的水凝胶已被证明在软骨细胞培养以及生长因子的持续释放方面非常有效，它被用于将纤维软骨细胞和具有成骨诱导作用的骨形态发生蛋白-2（BMP-2）局部递送到 FC 区域，以促进 FC 再生。在体外实验中，水凝胶结合的 FC 系统产生的钙和糖胺聚糖（GAG）明显多于没有水凝胶的 FC 样本和所有 LIG 样本，但胶原和 DNA 则少于后者。在体内皮下植入小鼠 8 周后，水凝胶结合的 FC 样本中分泌的钙和 GAG 含量在 6 周时优于或类似于体外水凝胶结合的 FC 样本。由于钙和 GAG 的产量增加，体内水凝胶结合的 FC 样本产生了所有样本中最高的压缩模量。组织学和免疫荧光分析以及元素分析也证实，与没有水凝胶的样本相比，水凝胶结合的 FC 系统在体外/体内均具有更密集和更均匀的钙、GAG、骨钙素和新生血管标志物分布。这些结果还表明了使用水凝胶添加 BMP-2 的有益效果。总之，使用基于肝素的水凝胶进行纤维软骨细胞和 BMP-2 的局部递送可以加速 LTB 特异性 FC 组织的成熟和分化，并且还可以在单个多孔 PLCL 支架中重建具有钙化 FC 和 LIG 组织的独特分层，在生化和生物力学特性方面都是如此。
