Division of Bioengineering, National University of Singapore, Singapore, Singapore.
Tissue Eng Part A. 2010 Jan;16(1):283-98. doi: 10.1089/ten.tea.2008.0537.
Biodegradable nanofibers have become a popular candidate for tissue engineering scaffolds because of their biomimetic structure that physically resembles the extracellular matrix. For certain tissue regeneration applications, prolonged in vitro culture time for cellular reorganization and tissue remodeling may be required. Therefore, extensive understanding of cellular effects on scaffold degradation is needed. There are only few studies on the degradation of nanofibers, and also the studies on degradation throughout cell culture are rare. In this study, polyglycolide (PGA), poly(DL-lactide-co-glycolide) (PLGA) and poly(L-lactide-co-epsilon-caprolactone) [P(LLA-CL)] were electrospun into nanofibrous meshes. The nanofibers were cultured with porcine smooth muscle cells for up to 3 months to evaluate their degradation behavior and cellular response. The results showed that the degradation rates are in the order of PGA >> PLGA > P(LLA-CL). PGA nanofibers degraded in 3 weeks and supported cell growth only in the first few days. PLGA nanofiber scaffolds facilitated cell growth during the first 30 days after seeding, but cell growth was slow thereafter. P(LLA-CL) nanofibers facilitated long-term (1-3 months) cell growth. mRNA quantification using real-time polymerase chain reaction revealed that some smooth muscle cell markers (alpha-actinin and calponin) and extracellular matrix genes (collagen and integrin) seemed to be downregulated with increased cell culture time. Cell culture significantly increased the degradation rate of PGA nanofibers, whereas the effect on PLGA and P(LLA-CL) nanofibers was limited. We found that the molecular weight of P(LLA-CL) and PLGA nanofibers decreased linearly for up to 100 days. Half lives of PLGA and P(LLA-CL) nanofibers were shown to be 80 and 110 days, respectively. In summary, this is the first study to our knowledge to evaluate long-term polymeric nanofiber degradation in vitro with cell culture. Cell culture accelerated the nanofibrous scaffold degradation to a limited extent. P(LLA-CL) nanofibers could be a good choice as scaffolds for long-term smooth muscle cell culture.
可生物降解的纳米纤维因其仿生结构而成为组织工程支架的热门候选材料，这种结构在物理上类似于细胞外基质。对于某些组织再生应用，可能需要延长细胞重组和组织重塑的体外培养时间。因此，需要广泛了解细胞对支架降解的影响。关于纳米纤维的降解，目前仅有少数研究，关于整个细胞培养过程中的降解研究则更为罕见。在这项研究中，聚乙醇酸（PGA）、聚（DL-乳酸-co-乙醇酸）（PLGA）和聚（L-乳酸-co-ε-己内酯）[P（LLA-CL）]被电纺成纳米纤维网。纳米纤维与猪平滑肌细胞共培养长达 3 个月，以评估其降解行为和细胞反应。结果表明，降解速率顺序为 PGA >> PLGA > P(LLA-CL)。PGA 纳米纤维在 3 周内降解，仅在最初几天支持细胞生长。PLGA 纳米纤维支架在接种后 30 天内促进细胞生长，但此后细胞生长缓慢。P(LLA-CL)纳米纤维促进了细胞的长期（1-3 个月）生长。实时聚合酶链反应的 mRNA 定量显示，一些平滑肌细胞标志物（α-肌动蛋白和钙调蛋白）和细胞外基质基因（胶原蛋白和整合素）似乎随着细胞培养时间的增加而下调。细胞培养显著提高了 PGA 纳米纤维的降解速率，而对 PLGA 和 P(LLA-CL)纳米纤维的影响有限。我们发现 P(LLA-CL)和 PLGA 纳米纤维的分子量在长达 100 天内呈线性下降。PLGA 和 P(LLA-CL)纳米纤维的半衰期分别为 80 天和 110 天。总之，这是我们所知的首次在体外进行细胞培养来评估长寿命聚合物纳米纤维的降解。细胞培养在有限程度上加速了纳米纤维支架的降解。P(LLA-CL)纳米纤维可能是平滑肌细胞长期培养的良好选择。
