Lee Soo-Hong, Kim Byung-Soo, Kim Soo Hyun, Choi Sung Won, Jeong Sung In, Kwon Il Keun, Kang Sun Woong, Nikolovski Janeta, Mooney David J, Han Yang-Kyoo, Kim Young Ha
Biomaterials Research Center, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, Korea.
J Biomed Mater Res A. 2003 Jul 1;66(1):29-37. doi: 10.1002/jbm.a.10497.
Cyclic mechanical strain has been demonstrated to enhance the development and function of engineered smooth muscle (SM) tissues, and it would be necessary for the development of the elastic scaffolds if one wishes to engineer SM tissues under cyclic mechanical loading. This study reports on the development of an elastic scaffold fabricated from a biodegradable polymer. Biodegradable poly(glycolide-co-caprolactone) (PGCL) copolymer was synthesized from glycolide and epsilon-caprolactone in the presence of stannous octoate as catalyst. The copolymer was characterized by (1)H-NMR, gel permeation chromatography and differential scanning calorimetry. Scaffolds for tissue engineering applications were fabricated from PGCL copolymer using the solvent-casting and particle-leaching technique. The PGCL scaffolds produced in this fashion had open pore structures (average pore size = 250 microm) without the usual nonporous skin layer on external surfaces. Mechanical testing revealed that PGCL scaffolds were far more elastic than poly(lactic-co-glycolic acid) (PLGA) scaffolds fabricated using the same method. Tensile mechanical tests indicated that PGCL scaffolds could withstand an extension of 250% without cracking, which was much higher than withstood by PLGA scaffolds (10-15%). In addition, PGCL scaffolds achieved recoveries exceeding 96% at applied extensions of up to 230%, whereas PLGA scaffolds failed (cracked) at an applied strain of 20%. Dynamic mechanical tests showed that the permanent deformation of the PGCL scaffolds in a dry condition produced was less than 4% of the applied strain, when an elongation of 20% at a frequency of 1 Hz (1 cycle per second) was applied for 6 days. Moreover, PGCL scaffolds in a buffer solution also had permanent deformations less than 5% of the applied strain when an elongation of 10% at a frequency of 1 Hz was applied for 2 days. The usefulness of the PGCL scaffolds was demonstrated by engineering SM tissues in vivo. This study shows that the elastic PGCL scaffolds produced in this study could be used to engineer SM-containing tissues (e.g. blood vessels and bladders) in mechanically dynamic environments.
循环机械应变已被证明可促进工程化平滑肌（SM）组织的发育和功能，若要在循环机械负荷下构建SM组织，开发弹性支架将很有必要。本研究报告了一种由可生物降解聚合物制成的弹性支架的开发情况。可生物降解的聚（乙交酯-共-己内酯）（PGCL）共聚物由乙交酯和ε-己内酯在辛酸亚锡作为催化剂的存在下合成。该共聚物通过（1）H-NMR、凝胶渗透色谱法和差示扫描量热法进行表征。用于组织工程应用的支架由PGCL共聚物采用溶剂浇铸和颗粒沥滤技术制成。以这种方式生产的PGCL支架具有开放的孔结构（平均孔径 = 250微米），外表面没有通常的无孔皮层。力学测试表明，PGCL支架比使用相同方法制造的聚（乳酸-共-乙醇酸）（PLGA）支架弹性大得多。拉伸力学测试表明，PGCL支架能够承受250%的伸长而不开裂，这远高于PLGA支架所能承受的伸长率（10 - 15%）。此外，在高达230%的施加伸长率下，PGCL支架的恢复率超过96%，而PLGA支架在20%的施加应变时就会失效（开裂）。动态力学测试表明，当在1 Hz（每秒1个循环）的频率下施加20%的伸长率持续6天时，干燥条件下PGCL支架产生的永久变形小于施加应变的4%。此外，当在1 Hz的频率下施加10%的伸长率持续2天时，缓冲溶液中的PGCL支架的永久变形也小于施加应变的5%。PGCL支架在体内构建SM组织方面的实用性得到了证明。本研究表明，本研究中生产的弹性PGCL支架可用于在机械动态环境中构建含SM的组织（如血管和膀胱）。
