Translational Center Würzburg "Regenerative Therapies for Oncology and Musculosceletal Diseases", Branch of Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB, Würzburg, Germany.
Department Tissue Engineering and Regenerative Medicine (TERM), University Hospital Würzburg, Würzburg, Germany.
J Tissue Eng Regen Med. 2018 Mar;12(3):e1474-e1479. doi: 10.1002/term.2565. Epub 2017 Nov 10.
Mesenchymal stem cells play a major role during bone remodelling and are thus of high interest for tissue engineering and regenerative medicine applications. Mechanical stimuli, that is, deformation strain and interstitial fluid-flow-induced shear stress, promote osteogenic lineage commitment. However, the predominant physical stimulus that drives early osteogenic cell maturation is not clearly identified. The evaluation of each stimulus is challenging, as deformation and fluid-flow-induced shear stress interdepend. In this study, we developed a bioreactor that was used to culture mesenchymal stem cells harbouring a strain-responsive AP-1 luciferase reporter construct, on porous scaffolds. In addition to the reporter, mineralization and vitality of the cells was investigated by alizarin red staining and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide. Quantification of the expression of genes associated to bone regeneration and bone remodelling was used to confirm alizarin red measurements. Controlled perfusion and deformation of the 3-dimensional scaffold facilitated the alteration of the expression of osteogenic markers, luciferase activity, and calcification. To isolate the specific impact of scaffold deformation, a computational model was developed to derive a perfusion flow profile that results in dynamic shear stress conditions present in periodically loaded scaffolds. In comparison to actually deformed scaffolds, a lower expression of all measured readout parameters indicated that deformation strain is the predominant stimulus for skeletal precursors to undergo osteogenesis in earlier stages of osteogenic cell maturation.
间充质干细胞在骨重塑过程中起着重要作用，因此它们是组织工程和再生医学应用的研究热点。机械刺激，即变形应变和间质液流动引起的剪切应力，促进成骨细胞系的分化。然而，驱动早期成骨细胞成熟的主要物理刺激尚未明确确定。由于变形和液流引起的剪切应力相互依存，因此评估每种刺激因素都具有挑战性。在这项研究中，我们开发了一种生物反应器，用于在多孔支架上培养携带应变响应 AP-1 荧光素酶报告基因构建体的间充质干细胞。除了报告基因外，还通过茜素红染色和 3-(4,5-二甲基噻唑-2-基)-2,5-二苯基四氮唑溴盐来研究细胞的矿化和活力。定量分析与骨再生和骨重塑相关的基因表达，以确认茜素红测量结果。3 维支架的受控灌注和变形促进了成骨标记物、荧光素酶活性和钙化的表达变化。为了分离支架变形的具体影响，开发了一个计算模型，以推导出导致周期性加载支架中存在动态剪切应力条件的灌注流型。与实际变形的支架相比，所有测量的读数参数的表达水平都较低，这表明在成骨细胞成熟的早期阶段，应变是骨骼前体细胞向成骨细胞分化的主要刺激因素。
