The Application Of Composite Poly(L-lactic-acid)/silk Fibroin Scaffold Prepared By Electrospinning In Cartilage Tissue Engineering

Cartilage damage caused by trauma, tumor, and inflammation is common in clinic, and the incidence of cartilage diseases will further increase because of aging problem, which seriously affects people’s quality of life and increases social burden. Due to their characteristics in structure and function, cartilage has a poor ability to regenerate after injury, so the patients always need to accept all kinds of conservative or surgical treatment, and some of them even cannot be cured and become permanent disabilities. But all the traditional treatments have the drawbacks that cannot be ignored, such as the secondary trauma of the autologous transplantation, the immune rejection and limited donors of the allografts and the worse properties of neotissue and poor long-term outcome by the bone marrow-stimulation.Tissue engineering bring the new hope for the repair of cartilage damage. Classic tissue engineering has three basic elements, namely seed cells, scaffold and biological factors. The scaffold is fabricated by related process with a specific shape, structure and properties, and a certain amount of seed cells are inoculated onto the scaffold. Under the procedural stimulation of biological factors, the cells will synthesized and secrete extracellular matrix according to scheduled program, and the scaffold will be the template to be assembled into a specific structure. At the same time, the scaffold gradually degrades to provide space for new tissue, so the damaged tissue or organs are repaired finally.In this experiment, we proposed to evaluate the application potential of poly-L-lactic acid(PLLA)/silk fibroin(SF) composite nanofibers by electrospinning in cartilage tissue engineering. First, we use SEM to observe the surface morphology of the scaffold, analyzing the diameter and distribution according to the images. The hydrophilicity can be evaluated by the contact angle and swelling ratios. The universal testing machine can evaluate the mechanical properties. And then chondrocytes as seed cells are inoculated on the scaffold, using SEM and CLSM to observe the adhension and shape of the cells and using biochemical experiment and histochemical staining to detect their ability to proliferate and synthesize and secrete extracellular matrix. At last, we use real-time quantitative PCR technology to detect the cartilage specific gene expression level of the chondrocytes on the scaffold and the ability to maintain phenotype or the degree of dedifferentiation and hypertrophy. The results of the above series of experiments show that PLLA/SF composite nanofiber scaffold by electrospinning has a good surface morphology and porous three-dimensional network structure, with good hydrophilic properties, so chondrocytes have the good adhesion, proliferation and secretion of extracellular matrix of cartilage, and cartilage-specific gene can be expressed at high levels. The phenotype of chondrocyte is relatively steady, and the extent of dedifferentiation and hypertrophy is lower. This ex-periment prove that electrospinning PLLA / SF composite nanofiber scaffold has a good application potential in cartilage tissue engineering, and laid the foundation for animal experiments and clinical post-conversion applications.