Fabrication and evaluation of biomimetic biodegradable tissue-engineered annulus fibrosus scaffold / 中国组织工程研究

ABSTRACT

BACKGROUND: It is still difficult to construct tissue-engineered anulus fibrosus scaffolds which have bionic structure, suitable biodegradability and good biocompatibility. OBJECTIVE: To fabricate bionic biodegradable scaffolds with polycaprolactone (PCL) and polydioxanone (PDS) and evaluate the feasibility as a tissue-engineered annulus fibrosus scaffold. METHODS: Five groups of scaffolds at different PCL/PDS proportions were prepared by melt spinning technique PCL, PCL/PDS70/30, PCL/PDS50/50, PCL/PDS30/70, and PDS groups. Scanning electron microscopy was used to observe the structure and measure the fiber diameter and pore size of these prepared scaffolds. The mechanical properties and contact angle of the scaffolds were measured. The in vitro and in vivo biodegradation of the scaffolds were observation by in vitro simulation and subcutaneous implantation. The expression of inflammatory factors interleukin-1β and tumor necrosis factor-α in the biodegraded tissues was detected. Human Wharton’s jelly mesenchymal stem cells were cultured for 7 days. Cell viability and proliferation was determined by live/dead cell staining. This study was approved by the Medical Ethics Committee of Tianjin Hospital, China on March 2, 2016. RESULTS AND CONCLUSION: Scanning electron microscopy results showed that the thickness of the scaffold fibers was uniform and the angle between fibers was 60°. The mechanical properties analysis showed that the tensile and compressive modulus of the PDS group was the lowest, which did not meet the mechanical requirements of the anulus fibrosus; the tensile and compressive modulus in the PCL group was the highest, and those in the PCL/PDS70/30 and PCL/PDS50/50 group were moderate. Hydrophilicity test showed that higher PDS proportion led to better hydrophilicity. Biodegradation test showed that the biodegradation of pure PDS and PCL/PDS30/70 was too fast, that of PCL was too slow, and that of PCL/PDS70/30 and PCL/PDS50/50 was appropriate. Analysis of inflammatory response around the biodegraded tissue showed that higher proportion of PCL in the scaffold resulted in more severe inflammatory response. CCK-8 and live/dead cell staining showed that human Wharton’s jelly mesenchymal stem cells had good proliferative activity and high survival rate in the PCL/PDS70/30, PCL/PDS50/50, and PCL/PDS30/70 groups. These results suggest that scaffolds in the PCL/PDS70/30 and PCL/PDS50/50 groups can simulate the structure of natural annulus fibrosus, have appropriate biodegradability, excellent mechanical properties and good biocompatibility, which make it a suitable candidate for tissue-engineered annulus fibrosus scaffold.