Department of Anatomy, Royal College of Surgeons in Ireland, 123 St. Stephens Green, Dublin 2, Ireland.
J Mech Behav Biomed Mater. 2012 Jul;11:53-62. doi: 10.1016/j.jmbbm.2011.11.009. Epub 2011 Dec 3.
In stem cell biology, focus has recently turned to the influence of the intrinsic properties of the extracellular matrix (ECM), such as structural, composition and elasticity, on stem cell differentiation. Utilising collagen-glycosaminoglycan (CG) scaffolds as an analogue of the ECM, this study set out to determine the effect of scaffold stiffness and composition on naive mesenchymal stem cell (MSC) differentiation in the absence of differentiation supplements. Dehydrothermal (DHT) and 1-ethyl-3-3-dimethyl aminopropyl carbodiimide (EDAC) crosslinking treatments were used to produce three homogeneous CG scaffolds with the same composition but different stiffness values: 0.5, 1 and 1.5 kPa. In addition, the effect of scaffold composition on MSC differentiation was investigated by utilising two glycosaminoglycan (GAG) types: chondroitin sulphate (CS) and hyaluronic acid (HyA). Results demonstrated that scaffolds with the lowest stiffness (0.5 kPa) facilitated a significant up-regulation in SOX9 expression indicating that MSCs are directed towards a chondrogenic lineage in more compliant scaffolds. In contrast, the greatest level of RUNX2 expression was found in the stiffest scaffolds (1.5 kPa) indicating that MSCs are directed towards an osteogenic lineage in stiffer scaffolds. Furthermore, results demonstrated that the level of up-regulation of SOX9 was higher within the CHyA scaffolds in comparison to the CCS scaffolds indicating that hyaluronic acid further influences chondrogenic differentiation. In contrast, enhanced RUNX2 expression was observed in the CCS scaffolds in comparison to the CHyA scaffolds suggesting an osteogenic influence of chondroitin sulphate on MSC differentiation. In summary, this study demonstrates that, even in the absence of differentiation supplements, scaffold stiffness can direct the fate of MSCs, an effect that is further enhanced by the GAG type used within the CG scaffolds. These results have significant implications for the therapeutic uses of stem cells and enhance our understanding of the physical effects of the in vivo microenvironment on stem cell behaviour.
在干细胞生物学中，研究重点最近转向了细胞外基质（ECM）的固有特性，如结构、组成和弹性，对干细胞分化的影响。本研究利用胶原-糖胺聚糖（CG）支架作为 ECM 的模拟物，旨在确定支架硬度和组成对无分化补充物的原始间充质干细胞（MSC）分化的影响。使用去水热（DHT）和 1-乙基-3-（3-二甲氨基丙基）碳二亚胺（EDAC）交联处理来制备三种具有相同组成但硬度值不同的同质 CG 支架：0.5、1 和 1.5 kPa。此外，通过利用两种糖胺聚糖（GAG）类型：硫酸软骨素（CS）和透明质酸（HyA），研究了支架组成对 MSC 分化的影响。结果表明，硬度最低（0.5 kPa）的支架促进了 SOX9 表达的显著上调，表明在更柔软的支架中，MSC 被定向为软骨谱系。相比之下，在最硬的支架（1.5 kPa）中发现了最高水平的 RUNX2 表达，表明在更硬的支架中，MSC 被定向为成骨谱系。此外，结果表明，与 CCS 支架相比，CHyA 支架中 SOX9 的上调水平更高，表明透明质酸进一步影响软骨分化。相比之下，与 CHyA 支架相比，CCS 支架中观察到增强的 RUNX2 表达，表明软骨素硫酸盐对 MSC 分化有成骨影响。总之，本研究表明，即使在没有分化补充物的情况下，支架硬度也可以指导 MSC 的命运，而 GAG 类型在 CG 支架中的使用进一步增强了这种作用。这些结果对干细胞的治疗用途具有重要意义，并增强了我们对体内微环境对干细胞行为的物理影响的理解。
