Finger Allison R, Sargent Carolyn Y, Dulaney Katherine O, Bernacki Susan H, Loboa Elizabeth G
Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State University, Raleigh, North Carolina 27695, USA.
Tissue Eng. 2007 Jun;13(6):1151-8. doi: 10.1089/ten.2006.0290.
This study investigated the differential effects of ramped and steady applications of cyclic hydrostatic pressure (CHP) on chondrogenic differentiation of bone marrow-derived human mesenchymal stem cells (hMSCs) in 3-dimensional culture in the absence of transforming growth factor-beta (TGF-beta). A custom hydrostatic pressure system was designed and manufactured. hMSCs were seeded in agarose and exposed to steady (7.5 MPa) or ramped (1 MPa to 7.5 MPa over a 14-day period) CHP for 4 h/d at f = 1 Hz for 14 days. Real-time reverse transcriptase polymerase chain reaction analysis was performed on days 0, 4, 9, and 14 to determine changes in messenger ribonucleic acid (mRNA) expression levels of Sox9, aggrecan, collagen I, and collagen II. Collagen II and aggrecan mRNA expression remained unchanged. Collagen I increased at day 4 in CHP specimens before decreasing to levels at or below same-day unloaded controls at days 9 and 14. On average, ramped and steady regimens of CHP increased Sox9, with the largest upregulation occurring at day 4 in response to steady pressure. These findings indicate that hydrostatic pressure may induce chondrogenesis in hMSC-seeded agarose constructs without TGF-beta, and that hMSCs are capable of withstanding high initial pressures that may initiate chondrogenesis faster than lower pressures.
本研究调查了在无转化生长因子-β（TGF-β）情况下，在三维培养中，循环静水压力（CHP）的斜坡式和稳定式施加对人骨髓间充质干细胞（hMSCs）软骨形成分化的不同影响。设计并制造了一个定制的静水压力系统。将hMSCs接种于琼脂糖中，并在f = 1 Hz条件下，每天暴露于稳定（7.5 MPa）或斜坡式（在14天内从1 MPa升至7.5 MPa）CHP 4小时，持续14天。在第0、4、9和14天进行实时逆转录聚合酶链反应分析，以确定性别决定区Y框蛋白9（Sox9）、聚集蛋白聚糖、I型胶原和II型胶原信使核糖核酸（mRNA）表达水平的变化。II型胶原和聚集蛋白聚糖mRNA表达保持不变。I型胶原在CHP样本的第4天增加，然后在第9天和第14天降至当天未加载对照水平或以下。平均而言，CHP的斜坡式和稳定式方案均增加了Sox9，在第4天对稳定压力的反应中上调幅度最大。这些发现表明，静水压力可能在无TGF-β的情况下诱导接种hMSC的琼脂糖构建体发生软骨形成，并且hMSCs能够承受高初始压力，高初始压力可能比低压力更快地启动软骨形成。
