Department of Orthopedics, University of Zurich, Zurich, Switzerland.
Biomaterials. 2010 Oct;31(30):7695-704. doi: 10.1016/j.biomaterials.2010.06.046. Epub 2010 Jul 24.
Substrates with mechanical property gradients and various extracellular matrix ligand loadings were evaluated for their ability to direct bone marrow stromal cell differentiation along osteogenic and tenogenic lineages. After verifying reproducible mechanical compliance characteristics of commercial hydrogel gradient substrates, substrates were functionalized with whole length fibronectin or collagen, both of which are found in skeletal structures and are relevant to cell-matrix signalling. Bone marrow stromal cells were seeded onto the substrates in growth media and cultured first to examine cell attachment and morphology, indicating higher levels of attachment on collagen substrates after 1h, and increased spreading and organization trends after 24h. Differentiation studies showed an increase in osteoblast differentiation on fibronectin substrates while collagen substrates lacked osteogenic differentiation. Osteogenic differentiation decreased on substrates of lower stiffness and lower ligand density. Molecular investigations revealed an increase in relevant signalling molecules for osteoblasts that were consistent with differentiation studies, but detected the presence of tenoblast markers on collagen substrates within a narrow range of stiffness. Our results indicate that mechanovariant substrates do hold promise as a culture platform for directed differentiation to tendon and bone by altering gene level expression of relevant signalling molecules. This study aids in understanding the molecular mechanisms that drive differentiation from substrate based cues, and could aid the design of therapeutic biomaterials at the transition from tendon to bone.
具有机械性能梯度和各种细胞外基质配体负载的底物被评估为其沿着成骨和成腱谱系指导骨髓基质细胞分化的能力。在验证了商业水凝胶梯度底物可重复的机械顺应性特征之后,用全长纤维连接蛋白或胶原蛋白对底物进行了功能化,这两种物质都存在于骨骼结构中,与细胞-基质信号转导有关。骨髓基质细胞在生长培养基中接种到底物上进行培养,首先检查细胞附着和形态,结果表明在 1 小时后,胶原底物上的附着水平更高,在 24 小时后,细胞扩散和组织化趋势增加。分化研究表明,纤维连接蛋白底物上成骨细胞的分化增加,而胶原底物缺乏成骨分化。在刚性较低和配体密度较低的底物上,成骨分化减少。分子研究表明,与分化研究一致,与成骨细胞相关的信号分子增加,但在较窄的刚度范围内检测到胶原底物上存在肌腱细胞标志物。我们的结果表明,机械变异性底物确实有希望成为通过改变相关信号分子的基因水平表达来指导向肌腱和骨骼分化的培养平台。这项研究有助于理解从基于底物的线索驱动分化的分子机制,并可能有助于在从肌腱到骨骼的过渡中设计治疗性生物材料。
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