可降解水性聚胺酯之兩階段藥物釋放支架於無細胞軟骨組織工程之應用

Abstract

3D列印技術在組織工程與再生醫學領域迅速發展，經由生物材料客製化出的軟骨組織工程支架，在和細胞結合以後可以達到修復受損組織的目的，因此成為一個相當有發展性的平台。目前軟骨組織工程支架中使用的細胞多於體外培養後植入體內，具有污染的風險，而無細胞的支架可能沒有足夠的治療效果，因此在臨床應用上仍然具有挑戰性。在本研究中，經由環保水性製程的技術，製作出水性3D列印墨水，以生物降解聚胺酯 (polyurethane, PU) 結合趨化因子SDF-1及載有小分子藥物Y27632的PU微米球，製作出兩階段性藥物釋放的可生物降解軟骨組織工程支架。製備方法是在PU分散液中加入趨化因子SDF-1及含有Y27632的PU微米球製成墨水，目的是利用SDF-1先隨著支架降解而釋出，吸引幹細胞遷移，而後在Y27632作用下，誘導遷移至支架的幹細胞軟骨化；在墨水中輔以聚氧乙烯做為增稠劑後，在低溫下(-40°C)列印成型。含有200 ng/ml的 SDF-1和22 wt% 包Y27632的微球 (微球中含有55 ug/ml 的Y27632)(縮寫為PU/SDF-1/MS_Y支架)的支架具有最佳的性能。支架的結構設計使得SDF-1和Y27632可以在體外依序釋放，並在適當的時間(分別在24小時和62小時)後達到各自的有效濃度(分別為~75 ng/ml和3.38 ug/ ml)，當幹細胞種植在PU/SDF-1/MS_Y支架中7天後，表現出顯著的GAG沉積且能促進幹細胞軟骨化。此外，從PU/SDF-1/MS_Y支架中釋放出的SDF-1也可誘導幹細胞遷移。在兔子關節軟骨缺損實驗中植入此無細胞的PU/SDF-1/MS_Y支架後具有良好的修復效果，說明此3D列印支架於客製化軟骨組織工程上具有可應用性。我們期望此可生物降解的3D列印支架能免去體外組織培養的繁複過程，並解決細胞來源不足的困境，增加組織工程支架在臨床方面應用的可能性。

Three dimensional (3D) printing technology has rapidly developed as a promising technology for manufacturing tissue engineering scaffolds. Cells used in tissue engineering are subjected to the quality management and risk of contamination, while cell-free scaffolds may not have sufficient therapeutic efficacy. In this study, water-based 3D printing ink containing biodegradable polyurethane (PU), chemokine SDF-1, and Y27632 drug-embedding PU microspheres was printed at low temperature (-40 °C) to fabricate tissue engineering scaffolds with sequential drug release function. The scaffolds containing 200 ng/ml SDF-1 and 22 wt% Y27632-encapsulated microspheres (55 ug/ml Y27632 in microspheres) (abbreviated PU/SDF-1/MS_Y scaffolds) had the optimal performance. The structural design of the scaffolds allowed each of SDF-1 and Y27632 to be released sequentially in vitro and reach the effective concentration (~100 ng/ml and 3.38 ug/ml, respectively) after the appropriate time (24 h and 62 h, respectively). Human mesenchymal stem cells (hMSCs) seeded in the scaffolds showed significant GAG deposition in 7 days. Besides, the gradual release of SDF-1 from the PU/SDF-1/MS_Y scaffolds could induce the migration of hMSCs. Implantation of the cell-free PU/SDF-1/MS_Y scaffolds in rabbit articular cartilage defects supported the potential of the scaffolds to promote cartilage regeneration. The 3D printed scaffolds with sequential releases of SDF-1 and Y27632 may have potential in cartilage tissue engineering.