A dual-crosslinked injectable hydrogel derived from muscular decellularized matrix promoting myoblasts proliferation and myogenic differentiation / 中国修复重建外科杂志

OBJECTIVE@#To investigate the feasibility of a dual-crosslinked injectable hydrogel derived from acellular musclar matrix (AMM) for promoting myoblasts proliferation and myogenic differentiation.@*METHODS@#Firstly, hyaluronic acid was oxidized with NaIO 4 and methylated to prepare methacrylamidated oxidized hyaluronic acid (MOHA). Then, AMM obtained by washing enzymatically treated muscle tissue was aminolyzed to prepare aminated AMM (AAMM). MOHA hydrogel and AAMM were crosslinked using Schiff based reaction and UV radiation to prepare a dual-crosslinked MOHA/AAMM injectable hydrogel. Fourier transform infrared spectroscopy (FTIR) was used to characterize MOHA, AAMM, and MOHA/AAMM hydrogels. The injectability of MOHA/AAMM hydrogel were evaluated by manual injection, and the gelation performance was assessed by UV crosslinking. The rheological properties and Young's modulus of the hydrogel were examined through mechanical tests. The degradation rate of the hydrogel was assessed by immersing it in PBS. The active components of the hydrogel were verified using immunofluorescence staining and ELISA assay kits. The promotion of cell proliferation by the hydrogel was tested using live/dead staining and cell counting kit 8 (CCK-8) assays after co-culturing with C2C12 myoblasts for 9 days. The effect of the hydrogel on myogenic differentiation was evaluated by immunofluorescence staining and real time quantitative polymerase chain reaction (RT-qPCR).@*RESULTS@#FTIR spectra confirmed the successful preparation of MOHA/AAMM hydrogel. The hydrogel exhibited good injectability and gelation ability. Compared to MOHA hydrogel, MOHA/AAMM hydrogel exhibited higher viscosity and Young's modulus, a reduced degradation rate, and contained a higher amount of collagen (including collagen type Ⅰ and collagen type Ⅲ) as well as bioactive factors (including epidermal growth factor, fibroblast growth factor 2, vascular endothelial growth factor, and insulin-like growth factor 1). The live/dead cell staining and CCK-8 assay indicated that with prolonged incubation time, there was a significant increase in viable cells and a decrease in dead cells in the C2C12 myoblasts within the MOHA/AAMM hydrogel. Compared with MOHA hydrogel, the difference was significant at each time point ( P<0.05). Immunofluorescence staining and RT-qPCR analysis demonstrated that the deposition of IGF-1 and expression levels of myogenic-related genes (including Myogenin, Troponin T, and myosin heavy chain) in the MOHA/AAMM group were significantly higher than those in the MOHA group ( P<0.05).@*CONCLUSION@#The MOHA/AAMM hydrogel prepared based on AMM can promote myoblasts proliferation and myogenic differentiation, providing a novel dual-crosslinked injectable hydrogel for muscle tissue engineering.

Thymosin beta4 increases mouse hair regeneration / 中国组织工程研究

BACKGROUND:Results of recent studies demonstrated the modulation of thymosin β4 on hair cycle and regeneration, but the mechanism of action remains unclear. OBJECTIVE:To investigate the mechanism by which thymosinβ4 increases hair regeneration through Wnt signal pathway. METHODS:After the mouse model of depilation was established using rosin/paraffin mixed agents, the experimental animals were randomly assorted to three different groups, including low-dose, high-dose and control groups, and a dose of 0.3μg/50μL, 3μg/50μL thymosinβ4 and PBS was administered on the depilated backs every 12 hours, respectively. Then photography, hematoxylin-eosin staining, immunohistochemistry and in situ hybridization were applied to observe the growth of hair, and the expressions ofβ-catenin and LEF-1 mRNA in different groups at different time were quantitatively evaluated. RESULTS AND CONCLUSION:The hair growth of the low-dose group was faster than that of the other groups. Hematoxylin-eosin staining demonstrated inflammatory cel s infiltration in the dermis after depilation, and the number of hair fol icles that were in the phase of anagen was much more than the other groups as time went by. Immunohistochemistry ofβ-catenin showed the accumulation of intra-cel ularβ-catenin in the low-dose group at the bulge of fol icles assessed by integrated absorbance analysis (P<0.05), so did the in situ hybridization of LEF-1 mRNA. Low-dose thymosinβ4 accelerates hair growth through Wnt signal pathway by elevating the level ofβ-catenin and LEF-1 mRNA.