Elder Benjamin D, Athanasiou Kyriacos A
Department of Bioengineering, Rice University, Houston, Texas 77251-1892, USA.
Tissue Eng Part A. 2009 May;15(5):1151-8. doi: 10.1089/ten.tea.2008.0200.
The objective of this study was to determine the effects of temporal hydrostatic pressure (HP) on the properties of scaffoldless bovine articular cartilage constructs. The study was organized in three phases: First, a suitable control for HP application was identified. Second, 10 MPa static HP was applied at three different timepoints (6-10 days, 10-14 days, and 14-18 days) to identify a window in construct development when HP application would be most beneficial. Third, the temporal effects of 10-14-day static HP application, as determined in phase II, were assessed at 2, 4, and 8 weeks. Compressive and tensile mechanical properties, GAG and collagen content, histology for GAG and collagen, and immunohistochemistry for collagen types I and II were assessed. When a culture control identified in phase I was used in phase II, HP application from 10 to 14 days resulted in a significant 1.4-fold increase in aggregate modulus, accompanied by an increase in GAG content, while HP application at all timepoints enhanced tensile properties and collagen content. In phase III, HP had an immediate effect on GAG content, collagen content, and compressive stiffness, while there was a delayed increase in tensile stiffness. The enhanced tensile stiffness was still present at 8 weeks. For the first time, this study examined the immediate and long-term effects of HP on biomechanical properties, and demonstrated that HP has an optimal application time in construct development. These findings are exciting as HP stimulation allowed for the formation of robust tissue-engineered cartilage; for example, 10 MPa static HP resulted in an aggregate modulus of 273 +/- 123 kPa, a Young's modulus of 1.6 +/- 0.4 MPa, a GAG/wet weight of 6.1 +/- 1.4%, and a collagen/wet weight of 10.6 +/- 2.4% at 4 weeks.
本研究的目的是确定时间性静水压力（HP）对无支架牛关节软骨构建体性能的影响。该研究分为三个阶段：第一，确定适合施加HP的对照。第二，在三个不同时间点（6 - 10天、10 - 14天和14 - 18天）施加10 MPa的静态HP，以确定在构建体发育过程中HP施加最有益的时间段。第三，在第2、4和8周评估在第二阶段确定的10 - 14天静态HP施加的时间效应。评估了压缩和拉伸力学性能、糖胺聚糖（GAG）和胶原蛋白含量、GAG和胶原蛋白的组织学以及I型和II型胶原蛋白的免疫组织化学。当在第二阶段使用第一阶段确定的培养对照时，10至14天施加HP导致聚集模量显著增加1.4倍，同时GAG含量增加，而在所有时间点施加HP均增强了拉伸性能和胶原蛋白含量。在第三阶段，HP对GAG含量、胶原蛋白含量和压缩刚度有即时影响，而拉伸刚度则延迟增加。增强的拉伸刚度在8周时仍然存在。本研究首次研究了HP对生物力学性能的即时和长期影响，并证明HP在构建体发育中有最佳施加时间。这些发现令人兴奋，因为HP刺激能够形成强健的组织工程软骨；例如，在4周时，10 MPa的静态HP导致聚集模量为273±123 kPa，杨氏模量为1.6±0.4 MPa，GAG/湿重为6.1±1.4%，胶原蛋白/湿重为10.6±2.4%。
