ABSTRACT
BACKGROUND: At present, cell patch technology has been widely used in the repair of various tissues and organs such as periodontal ligament, cornea, heart, cartilage, and esophagus. However, the effect and mechanism of basic fibroblast growth factor (bFGF) on the proliferation and osteogenic differentiation of bone marrow mesenchymal stem cell patches are still unknown. It is of great significance for understanding how to integrate growth factor with tissueengineered cell patch technology for the final use in tissue engineering repairing. OBJECTIVE: To investigate the expression of angiogenesis-related factors in rat bone marrow mesenchymal stem cell patch during bFGF-induced osteogenic differentiation. METHODS: After isolation, purification and identification, rat bone marrow mesenchymal stem cell patches were constructed by continuous induction of vitamin C and divided into two groups: bFGF group (20 µg/L bFGF+osteoinductive medium) and control group (osteoinductive medium). The expression of angiogenesis-related genes was detected by alizarin red staining at 7 and 14 days of osteogenic induction and by fluorescence quantitative PCR method at 10 days of osteogenic induction. RESULTS AND CONCLUSION: The results of alizarin red staining showed that the number of calcified nodules in the bFGF group was significantly higher than that in the control group. The expression of transforming growth factor Β1 mRNA in the bFGF group was significantly higher than that in the control group, while the expression of vascular endothelial growth factor, angiopoietin 1 and platelet-derived factor BB was lower than that in the control group. Together, these results demonstrate that bFGF can induce the osteogenic differentiation of rat bone marrow mesenchymal stem cell patches, and increase the expression of transforming growth factor Β1 in the late osteogenic stage.
ABSTRACT
Clustered regularly interspaced short palindromic repeats (CRISPR) are acquired immune system in bacteria and archaea. This system is used in site-directed gene editing. Recently, scientists discovered new CRISPR-associated (Cas) proteins, in which Cas12a-mediated gene editing can significantly reduce the off-target rate. In this article, we review CRISPR/Cas system's discovery of history, composition, classification, and working principle. The latest research progress of the CRISPR/Cas system, and its application in zebrafish are introduced.
ABSTRACT
BACKGROUND:With the promotion of 3D printing technology, 3D printing scaffolds for bone tissue engineering have become the new ideas for jaw bone repair. OBJECTIVE:To compare the physical and biological properties of sheep vertebral bone meal/polyvinyl alcohol (PVA) scaffold, nano-hydroxyapatite (nHA)/PVA scaffold, and sheep vertebral bone meal/PVA nonporous bone plate. METHODS:3D printing technology was used to print sheep vertebral bone meal/PVA scaffold, nHA/PVA scaffold, and sheep vertebral bone meal/PVA nonporous bone plate. Porosity, morphology, water absorption rate and mechanical properties of different scaffolds were detected. Three kinds of scaffolds were al used to culture bone marrow mesenchymal stem cel s, and cel proliferation ability was detected using cel counting kit-8 at 1, 4, 7 days of culture. RESULTS AND CONCLUSION:Under scanning electron microscope, the sheep vertebral bone meal/PVA scaffold and nHA/PVA scaffold exhibited regular and interconnected pores with good continuity and clear network structure;the sheep vertebral bone meal/PVA nonporous bone plate had no obvious pores;however, it had dense and evenly distributed micropores with different sizes on its surface. The porosity of nHA/PVA scaffold was lower than that of the sheep vertebral bone meal/PVA scaffold (P<0.05). The water absorption rate was highest for the nHA/PVA scaffold fol owed by the sheep vertebral bone meal/PVA scaffold and the sheep vertebral bone meal/PVA nonporous bone plate (P<0.05). In contrast, the scaffold toughness was highest for the sheep vertebral bone meal/PVA nonporous bone plate, fol owed by the sheep vertebral bone meal/PVA scaffold and nHA/PVA scaffold. In addition, the cel proliferation activity of cel s cultured on the sheep vertebral bone meal/PVA scaffold was significantly higher than that cultured on the other two kinds of scaffolds. Taken together, the 3D printing sheep vertebral bone/PVA scaffold has good physical and chemical performance.