Self-assembling Peptide Sciobio-Ⅱ For Articular Cartilage Injury Repairing

The self-assembly peptide Sciobio-II used in our research is composed of 16 amino acids.The purpose of this research was to explore the mechanism of action of peptide Sciobio-II by three-dimensional culture of chondrocytes and repair of cartilage injury in rabbit knee joint.Circular dichroism(CD)spectrum was applied to compare the secondary structure change of peptide after adding the growth factors and ions.Atomic force microscope(AFM)was used to detect the microstructure of peptide Sciobio-II and Sciobio-II added growth factors.Congo red staining was used to macroscopically observe the ability of peptide hydrogel to form a membrane.In vitro,the hydrogel scaffold formed by peptide Sciobio-II was used as a support material for three-dimensional culture of chondrocytes,the proliferation of cells were detected by CCK-8 and fluorescent staining methods.The expression of mRNA were quantitatively analyzed by real time q-PCR in two-dimensional and three-dimensional environments.Cell cycle was detected by flow cytometry.A model of rabbit articular cartilage injury was established in vivo experiments.MRI was applied to quantitatively analyze the repair of cartilage injury;HE staining and immunohistochemistry were used to determine the pathological changes of cartilage injury repair process.The results showed that the secondary structure of peptide Sciobio-II did not changed after added the growth factors and ions,and remained the β-sheet structure.The results of AFM showed that peptide Sciobio-II could form a nano-network scaffold structure after self-assembly for 24 h.It was a hydrogel under macroscopic conditions,which could complete the three-dimensional culture of cells.Human chondrocytes C28/I2 can survive and proliferate in the three-dimensional environment constructed by the peptide Sciobio-II.Cell experiments showed that after 7 days culture,the number of cells in proliferation phase was more than that in two-dimensional environment,and chondrocytes were in a good condition.The results of q-PCR showed that the mRNA expression of the cells cultured in three-dimensional environment continued to increase after 7 days culture.Animal experiments showed that both peptide hydrogel and BMP-2 encapsulated peptide Sciobio-II could accelerate the repair process of cartilage injury.MRI results showed that unhealed wound width of the control was 2.3 times that of peptide Sciobio-II after 8 weeks.The results of HE staining and immunohistochemistry(Collagen II,BMP-2)showed that after 12 weeks the blank group formed a small amount of regenerated tissue,and the boundary with normal tissues was clear.The peptide hydrogel and BMP-2 wrapped with peptide Sciobio-II had a better repair effect,which formed hyaline cartilage was close to the normal tissue,and the expression levels of Collagen II and BMP-2 were higher than that of the blank group.The controlled release rate of the 5 mg/ml was higher than 2.5 mg/ml,and the controlled release rates of BSA and BMP-2 were 86% and 94%,respectively.Our study found that the self-assembly peptide Sciobio-II can be used for three-dimensional culture of chondrocytes.Nano-scaffold materials simulating ECM function can stimulate the repair ability of damaged tissues and control release of the relevant growth factors.It has a good repairing effect on rabbit knee cartilage injury,and provides a new method for the treatment of cartilage injury,which has important application value and social significance in clinical.