ABSTRACT
The mobilization efficiency of granulocyte colony-stimulating factor (G-CSF) and stem cell factor (SCF) to bone marrow mononuclear cells (MNCs) in mice was observed,and the changes of CXCL12/CXCR4 signal were detected in order to find out the mobilization mechanism of stem cells.Kunming mice were randomly divided into two groups.The mice in treatment group were subjected to subcutaneous injection of G-CSF at a dose of 100 μg/kg and SCF at a dose of 25 μg/kg every day for 5 days,and those in control group were given isodose physiological saline.The MNCs were separated,counted and cultured,and the colony-forming unit-fibroblast (CFU-F) was evaluated.CD34+CXCR4+ MNCs were sorted by flow cytometry.The expression of CXCL12 protein in bone marrow extracellular fluid was detected by ELISA,and that of CXCL12 mRNA in bone marrow was measured by RT-PCR.The results showed that the counts of MNCs in peripheral blood and bone marrow were increased after administration of G-CSF/SCF (P＜0.01).The factors had a dramatic effect on the expansion capability of CFU-F (P＜0.05).Flow cytometric of bone marrow MNCs surface markers revealed that CD34+CXCR4+ cells accounted for 44.6%±8.7% of the total CD34+ MNCs.Moreover,G-CSF/SCF treatment induced a decrease in bone marrowCXCL12 mRNA that closely mirrored the fall in CXCL12 protein.In this study,it is evidenced that G-CSF/SCF can effectively induce MNCs mobilization by disrupting the balance of CXCL12/CXCR4 signaling pathway in the bone marrow and down-regulating the interaction of CXCL12/CXCR4.
ABSTRACT
In order to investigate the effect ofArg-Gly-Asp (RGD) peptide-modified silk biomaterial on the adhesion and proliferation of bone marrow-derived mesenchymal stem cells (MSCs),MSCs of third generation were seeded onto the surface of RGD-decorated silk (silk-RGD group),silk alone (silk group) or tissue culture plate (TCP group).After incubation for 4 or 12 h,MSCs were examined quantitatively by using precipitation method for cell attachment.The cell proliferation,which was de-fined as cell density,was compared among the three groups after culture for 1,2,3,and 4 days.Cell skeleton,which was labeled fluorescently,was observed under laser confocal microscope after 24 h of culture.The results showed that cell adhesion rate in silk-RGD group was higher than in silk group (P<0.05),but similar to that in TCP group after incubation for 4 or 12 h (P>0.05).There were no sig-nificant differences in the cell proliferation among the three groups at different time points (P>0.05 for all).Laser confocal microscopy revealed that in silk-RGD group,MSCs,strongly fluorescently stained,spread fully,with stress fibers clearly seen,while in silk group,actin filaments were sparsely aligned and less stress fibers were found.It was concluded that RGD peptide could improve the ad-hesion of MSCs to the silk scaffold,but had no impact on the proliferation of the cells.