Wang Yongzhong, Rudym Darya D, Walsh Ashley, Abrahamsen Lauren, Kim Hyeon-Joo, Kim Hyun S, Kirker-Head Carl, Kaplan David L
Department of Chemical and Biological Engineering, Tufts University, 4 Colby Street, Medford, MA 02155, USA.
Biomaterials. 2008 Aug-Sep;29(24-25):3415-28. doi: 10.1016/j.biomaterials.2008.05.002. Epub 2008 May 27.
Three-dimensional porous scaffolds prepared from regenerated silk fibroin using either an all-aqueous process or a process involving an organic solvent, hexafluoroisopropanol (HFIP), have shown promise in cell culture and tissue engineering applications. However, their biocompatibility and in vivo degradation have not been fully established. The present study was conducted to systematically investigate how processing method (aqueous vs. organic solvent) and processing variables (silk fibroin concentration and pore size) affect the short-term (up to 2 months) and long-term (up to 1 year) in vivo behavior of the protein scaffolds in both nude and Lewis rats. The samples were analyzed by histology for scaffold morphological changes and tissue ingrowth, and by real-time RT-PCR and immunohistochemistry for immune responses. Throughout the period of implantation, all scaffolds were well tolerated by the host animals and immune responses to the implants were mild. Most scaffolds prepared from the all-aqueous process degraded to completion between 2 and 6 months, while those prepared from organic solvent (hexafluoroisopropanol (HFIP)) process persisted beyond 1 year. Due to widespread cellular invasion throughout the scaffold, the degradation of aqueous-derived scaffolds appears to be more homogeneous than that of HFIP-derived scaffolds. In general and especially for the HFIP-derived scaffolds, a higher original silk fibroin concentration (e.g. 17%) and smaller pore size (e.g. 100-200microm) resulted in lower levels of tissue ingrowth and slower degradation. These results demonstrate that the in vivo behavior of the three-dimensional silk fibroin scaffolds is related to the morphological and structural features that resulted from different scaffold preparation processes. The insights gained in this study can serve as a guide for processing scenarios to match desired morphological and structural features and degradation time with tissue-specific applications.
采用全水相法或涉及有机溶剂六氟异丙醇（HFIP）的方法制备的三维多孔再生丝素蛋白支架，在细胞培养和组织工程应用中显示出了潜力。然而，它们的生物相容性和体内降解情况尚未完全明确。本研究旨在系统地探究加工方法（水相法与有机溶剂法）和加工变量（丝素蛋白浓度和孔径）如何影响蛋白质支架在裸鼠和Lewis大鼠体内的短期（长达2个月）和长期（长达1年）行为。通过组织学分析样品，观察支架的形态变化和组织长入情况，并通过实时RT-PCR和免疫组织化学分析免疫反应。在整个植入期间，所有支架均被宿主动物良好耐受，对植入物的免疫反应轻微。大多数采用全水相法制备的支架在2至6个月内完全降解，而采用有机溶剂（六氟异丙醇（HFIP））法制备的支架在1年以上仍有残留。由于整个支架中广泛的细胞侵入，水相衍生支架的降解似乎比HFIP衍生支架更均匀。总体而言，尤其是对于HFIP衍生的支架，较高的原始丝素蛋白浓度（例如17%）和较小的孔径（例如100 - 200微米）导致较低的组织长入水平和较慢的降解速度。这些结果表明，三维丝素蛋白支架的体内行为与不同支架制备过程所产生的形态和结构特征有关。本研究获得的见解可为加工方案提供指导，以便将所需的形态和结构特征以及降解时间与特定组织应用相匹配。
