Degradation rate of collagen-chitosan composite scaffold implanted into different rat tissues

doi:10.3969/j.issn.2095-4344.2017.06.008

Abstract：BACKGROUND:Biological scaffolds should be gradually degraded with the formation of new tissues, so the degradation rate is an important index for evaluating scaffold materials. Conventional testing methods make an impact on the assessment of the scaffold degradation rate at different sites due to some limitations. OBJECTIVE:To evaluate the degradation rate of col agen-chitosan (CG-CS) composite implanted into the subcutaneous, spinal cord and brain tissues of Sprague-Dawley rats and to explore the underlying mechanism. METHODS:A 3 mm×3 mm disc-shaped CG-CS composite scaffold was prepared, and its microstructure was observed under scanning electron microscope. Nerve stem cel s were co-cultured with CG-CS scaffold, and then the cel viability was detected through cel counting kit-8 assay to assess the biocompatibility. Sprague-Dawley rats were randomly divided into three groups:cortex, spinal cord, and subcutaneous groups. The CG-CS scaffold was implanted into cortex, spinal cord T9, or back T9, respectively. The rats were sacrificed at different time points, and three rats in each group were subjected to the scaffold removal to evaluate the scaffold degradation rate. The resting rats were used to prepare the tissue sections for histological observation of the scaffold and the surrounding tissues. RESULTS AND CONCLUSION:Scanning electron microscope revealed that the CG-CS composite scaffold had a three-dimensional porous structure with a pore size that met the biological requirements of in vivo transplantation. The in vivo experiments showed that no graft rejection occurred, suggesting that the scaffold has good biocompatibility. The degradation rate was fastest in the subcutaneous group, and the scaffold was degraded completely with 12 days, which was significantly higher than that in the spinal cord and brain groups (P<0.05). The degradation rate in the spinal cord group was significantly higher than that in the brain group since the 3rd week (P<0.05);the scaffold degraded completely in the spinal cord group, while the partial scaffold could still be found in the brain group. The number of blood vessels and the scores of macrophage infiltration were as fol ows:subcutaneous group>spinal cord group>brain group (P<0.05). Our findings suggest that the CG-CS scaffold holds a good biocompatibility and its degradation rate differs significantly among groups. In the field of tissue engineering, the complex microenvironment of target tissues and the host response after stent implantation should have effects on the balance between the biodegradation rate and reconstitution rate of the organism.