Deyu Duan

Effect of RGD-modified silk material on the adhesion and proliferation of bone marrow-derived mesenchymal stem cells.

SummaryIn order to investigate the effect of Arg-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 defined 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 significant 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 adhesion of MSCs to the silk scaffold, but had no impact on the proliferation of the cells.In order to investigate the effect of Arg-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 defined 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 significant 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 adhesion of MSCs to the silk scaffold, but had no impact on the proliferation of the cells.

G-CSF/SCF exert beneficial effects via anti-apoptosis in rabbits with steroid-associated osteonecrosis

OBJECTIVES Osteonecrosis is also known as avascular necrosis, and two types of cell death are included in the pathogenesis of osteonecrosis: necrosis and apoptosis. Apoptosis in the osteonecrosis of femoral head is thought to be the key determinant of glucocorticoid-induced cortical bone loss. The present study was implemented to evaluate the anti-apoptotic effect of Granulocyte colony-stimulating factor and stem cell factor (G-CSF/SCF) in rabbits with steroid-induced osteonecrosis. METHODS In the experiment, osteonecrosis was induced by low-dose lipopolysaccharide and subsequent pulsed high-dose methylprednisolone. Rabbits in preventive medicine group were treated with 100 μg/kg/d G-CSF and 25 μg/kg/d SCF. Then hematological and histomorphometric methods were used to investigate the treatment effects of osteonecrosis. Apoptosis was assessed via quantitative TUNEL staining and activated caspase-3 immunostaining and immunoblotting. RESULTS The results showed that G-CSF/SCF treatment could increase the secretion of serum osteocalcin, but inhibit the expression of serum tartrate-resistant acid phosphatase (TRAP5b). The incidence of osteonecrosis was significantly decreased in Preventive group when compared with Steroid group (42.1% vs. 88.2%). Histomorphometric analysis showed that G-CSF/SCF pre-disposal treatment was able to increase trabecular mineral appositional rate (MAR) and bone formation rate (BFR). Quantitative TUNEL and activated caspase-3 levels showed lower apoptosis in the Preventive group. CONCLUSIONS In conclusion, G-CSF/SCF treatment could inhibit caspase-3-dependent apoptosis in osteocytes to exert beneficial effects in preventing steroid-induced ON in rabbit models.

Mobilization Efficiency of Granulocyte Colony-stimulating Factor and Stem Cell Factor to Bone Marrow Mononuclear Cells and Mechanisms

SummaryThe 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 marrow CXCL12 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.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 marrow CXCL12 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.

Functional outcome of limb-salvage surgery with shoulder abduction brace for bone tumors around the shoulders.

The current trend is toward salvage of the extremity after tumor excision without compromising the extent of resection for bone tumor around the shoulders.