Bio-inspired Cell Membrane Ingredient Cholesterol-conjugated Chitosan as a Potential Material for Bone Tissue Repair

We prepared a cholesterol-conjugated chitosan（CHCS） material and evaluated its potential application as a bone tissue repair material by in vitro cell experiments. Cell proliferation, differentiation and morphology on CHCS membrane surfaces with different graft degrees were assessed in mouse pre-osteoblasts MC3T3-E1 cells. The results indicate that CHCS materials could promote the proliferation of MC3T3-E1 cells at low graft degrees, but the CHCS material with high graft degree inhibits the proliferation of cells in contrast to the pure chitosan membrane. However, the alkaline phosphatase（ALP） activity of MC3T3-E1 ceils on different CHCS membrane surface increased with in- creasing graft degrees of cholesterol. The area of cells stretched onto the surface of CHCS materials was larger than on the surface of CS materials, and more microfilaments and stress fibers in cells were observed on CHCS materials than on the pure chitosan material surface. After 7 d, the expression of related osteogenic marker genes, such as rum-related transcription factor 2（Runx2）, osterix（OSX）, osteocalcin（OCN）, osteopontin（OPN）, ALP and collagen I（COL-I） were all up-regulated in CHCS materials to different degrees compared to pure chitosan material, which in- dicated that the CHCS materials facilitated MC3T3-EI cell differentiation and maturation, Characterizing CHCS materials is useful in designing and developing strategies for bone tissue engineering.