McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, University of Pennsylvania, Philadelphia, PA 19104, USA.
Osteoarthritis Cartilage. 2009 Dec;17(12):1639-48. doi: 10.1016/j.joca.2009.07.003. Epub 2009 Jul 15.
Engineering cartilage requires that a clinically relevant cell type be situated within a 3D environment that supports cell viability, the production and retention of cartilage-specific extracellular matrix (ECM), and eventually, the establishment of mechanical properties that approach that of the native tissue. In this study, we investigated the ability of bone marrow derived mesenchymal stem cells (MSCs) to undergo chondrogenesis in crosslinked methacrylated hyaluronic acid hydrogels (MeHA) of different macromer concentrations (1, 2, and 5%).
Over a 6 week culture period under pro-chondrogenic conditions, we evaluated cartilage-specific gene expression, ECM deposition within constructs and released to the culture media, and mechanical properties in both compression and tension. Further, we examined early matrix assembly and long term histological features of the forming tissues, as well as the ability of macromolecules to diffuse within hydrogels as a function of MeHA macromer concentration.
Findings from this study show that variations in macromer density influence MSC chondrogenesis in distinct ways. Increasing HA macromer density promoted chondrogenesis and matrix formation and retention, but yielded functionally inferior constructs due to limited matrix distribution throughout the construct expanse. In 1% MeHA constructs, the equilibrium compressive modulus reached 0.12MPa and s-GAG content reached nearly 3% of the wet weight, values that matched or exceeded those of control agarose constructs and that are 25 and 50% of native tissue levels, respectively.
These data provide new insight into how early matrix deposition regulates long term construct development, and defines new parameters for optimizing the formation of functional MSC-based engineered articular cartilage using HA hydrogels.
工程软骨需要将一种临床相关的细胞类型置于支持细胞活力、软骨特异性细胞外基质（ECM）的产生和保留的 3D 环境中，并最终建立接近天然组织的机械性能。在这项研究中，我们研究了骨髓间充质干细胞（MSCs）在不同大分子浓度（1%、2%和 5%）交联甲基丙烯酰化透明质酸水凝胶（MeHA）中向软骨分化的能力。
在 6 周的软骨形成条件下培养，我们评估了软骨特异性基因表达、构建物内和释放到培养基中的 ECM 沉积以及压缩和拉伸的机械性能。此外，我们检查了早期基质组装和形成组织的长期组织学特征，以及大分子在水凝胶中的扩散能力随 MeHA 大分子浓度的变化。
本研究的结果表明，大分子密度的变化以不同的方式影响 MSC 软骨形成。增加 HA 大分子密度可促进软骨形成和基质形成和保留，但由于基质在整个构建物中的分布有限，导致功能较差的构建物。在 1% MeHA 构建物中，平衡压缩模量达到 0.12MPa，s-GAG 含量达到湿重的近 3%，这些值与对照琼脂糖构建物相匹配或超过，分别是天然组织水平的 25%和 50%。
这些数据提供了新的见解，即早期基质沉积如何调节长期构建物的发展，并为使用 HA 水凝胶优化基于 MSC 的功能性工程关节软骨的形成提供了新的参数。
