MESENCHYMAL STEM CELLS PRODUCE FUNCTIONAL CARTILAGE MATRIX IN THREE-DIMENSIONAL CULTURE IN REGIONS OF OPTIMAL NUTRIENT SUPPLY
MESENCHYMAL STEM CELLS PRODUCE FUNCTIONAL CARTILAGE MATRIX IN THREE-DIMENSIONAL CULTURE IN REGIONS OF OPTIMAL NUTRIENT SUPPLY
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DOI：
10.22203/ecm.v023a33
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发表时间：
2012-01-01
影响因子：
3.1
通讯作者：
Mauck, Robert L.
中科院分区：
文献类型：
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作者：
Farrell, Megan J.;Comeau, Eric S.;Mauck, Robert L.
间充质干细胞（MSCs）是治疗肌肉骨骼疾病的一种有前景的细胞来源。然而，在三维培养中，间充质干细胞的软骨形成所产生的构建体，其宏观（整体）力学性能不如由软骨细胞形成的构建体。为了探究这些功能缺陷在何处以及为何出现，我们评估了载有细胞的水凝胶构建体的局部（微观）特性。载有软骨细胞和间充质干细胞的构建体都表现出明显的深度依赖性，从表面到中心区域，模量分别降低了约3.5倍和约11.5倍。重要的是，在表面区域，特性相似，这表明间充质干细胞能够产生与软骨细胞力学等效的基质，但仅在营养供应充足的条件下。在轨道摇床上进行动态培养（这可增强扩散），与自由溶胀条件相比，减弱了力学性能上的深度依赖性差异，并改善了整体性能（软骨细胞为225至438 kPa，间充质干细胞为122至362 kPa）。然而，由于中心区域持续存在力学缺陷，基于间充质干细胞的构建体的性能仍然显著较低。这些中心区域的间充质干细胞活力显著下降，早在第21天这些变化就很明显，而软骨细胞活力仍然很高。这些发现表明，在最佳营养条件下，间充质干细胞能够进行软骨形成，并形成与天然组织细胞类型相当的功能性组织。然而，中心区域缺乏活力和基质产生表明，软骨形成的间充质干细胞尚未完全重现软骨细胞的高级表型，软骨细胞是一种经过优化能够在力学挑战性大且营养匮乏的环境中生存（并茁壮成长）的细胞。
Mesenchymal stem cells (MSCs) are a promising cell source for the treatment of musculoskeletal disease. However, MSC chondrogenesis in 3D culture generates constructs whose macroscopic (bulk) mechanical properties are inferior to constructs formed with chondrocytes. To investigate where and why these deficits in functionality arise, we assessed the local (microscopic) properties of cell-laden hydrogel constructs. Both chondrocyte- and MSC-laden constructs showed pronounced depth dependency, with similar to 3.5 and similar to 11.5 fold decreases in modulus from the surface to central regions, respectively. Importantly, in the surface region, properties were similar, suggesting that MSCs can produce matrix of mechanical equivalence to chondrocytes, but only in conditions of maximal nutrient support. Dynamic culture on an orbital shaker (which enhances diffusion) attenuated depth-dependent disparities in mechanics and improved the bulk properties compared to free swelling conditions (225 to 438 kPa for chondrocytes, 122 to 362 kPa for MSCs). However, properties in MSC-based constructs remained significantly lower due to persistent mechanical deficits in central regions. MSC viability in these central regions decreased markedly, with these changes apparent as early as day 21, while chondrocyte viability remained high. These findings suggest that, under optimal nutrient conditions, MSCs can undergo chondrogenesis and form functional tissue on par with that of the native tissue cell type. However, the lack of viability and matrix production in central regions suggests that chondrogenic MSCs do not yet fully recapitulate the advanced phenotype of the chondrocyte, a cell that is optimized to survive (and thrive) in a mechanically challenging and nutrient-poor environment.