ABSTRACT
Objective:To prepare the multilayer alginate chitosan microspheres loading vascular endothelial growth factor (VEGF) and vancomycin (VAN), and to study in vitro release characteristics.Methods:The microspheres were prepared by emulsion cross-linking and self-assembly techniques.The effects of sodium alginate concentration, calcium chloride concentration, oil/water ratio and span80 concentration on the entrapment efficiency(EE) and drug loading(DL) of VEGF and VAN were investigated by orthogonal experimental design to optimize the preparation process.The surface morphology and particle size of microspheres were observed by scanning electron microscope (SEM).Self-assembly was detected by Fourier transform infrared spectroscope (FTIR).The EE, DL and in vitro release of VEGF and VAN were detected by ELISA double antibody sandwich method and ultraviolet spectrophotometry,and the cumulative release curve was drawn.Results:The prepared microspheres were yellowish brown powder.The SEM results showed that the microspheres were spherical, the surface was smoothy, and the dispersity was better.The average particle size was about 50 μm.Sodium alginate concentration of 1.0 g·mL-1, CaCl2 concentration of 8 g·mL-1, oil to water ratio of 3∶1, and span80 concentration of 2% were the best formula.The EE of VEGF and VAN were 49.63% and 16.67%, respectively.In vitro, the cumulative release last 16.5 d and 12.5 d respectively and the amount reached up to 95%.Conclusion:The multilayer alginate chitosan microspheres loading VEGF and VAN present several advantages, such as smaller particle size, higher EE and better controlled release.
ABSTRACT
Objective:To investigate the influence of multilayer alginate chitosan sustained-release microspheres loading vascular endothelial growth factor(VEGF) and vancomycin in the proliferation and osteogenic differentiation of human plaacenta-derived mesen chymal stem cells(HPMSCs),and to provide theoretical basis for its clinical application in the repair of bone defect.Methods:The microspheres were prepared based on the previous research and HPMSCs were co-cultured with drug (VEGF/vancomycin)-loaded microspheres (drug-loaded microspheres+HPMSCs group), non-drug loaded microspheres (microspheres+HPMSCs group) and without any microspheres (HPMSCs group).Then the proliferation rate of HPMSCs was identified by CCK-8 kit.The osteogenic differentiation potential of HPMSCs was detected by Alizarin red staining and alkaline phosphatase (ALP) kit when the HPMSCs had been co-cultured with drug loaded microspheres in osteogenic medium (HPMSCs+drug-loaded microspheres+induction group), non-drug loaded microspheres in osteogenic medium (HPMSCs+microspheres+induction group), without any microspheres in osteogenic medium (HPMSCs+induction group) and without any micropheres in normal medium (HPMSCs+PBS group) for 21 d.Results:Compared with HPMSCs group,the proliferation rates of HPMSCs in drug-loaded microspheres+HPMSCs and microspheres+HPMSCs groups had no significant changes (P>0.05).The calcium deposition in HPMSCs+drug-loaded microspheres+induction group was more than those in microspheress+HPMSCs+indution group and HPMSCs+induction group after Aalizarin red staining;the ALP activity in drug-loaded microspheres+HPMSCs+indution group was higher than those in microspheres+HPMSCs+indution group and HPMSCs+induction group (P<0.05),and the ALP activity in microspheres+HPMSCs+induction group was higher than that in HPMSCs+induction group(P<0.05).Conclusion:The sustained-release microspheres loading VEGF and vancomycin have no significant effect on the proliferation activity of HPMSCs and the microspheres could stimulate the osteogenic differentiation of HPMSCs.
ABSTRACT
BACKGROUND:Magnesium can be degraded voluntarily in vivo, so a second surgery is avoided. However, its aloys have not been widely used in the clinical orthopedics because there is a lack of accurate and reliable methods to assess its degradationin vivo. OBJECTIVE:To explore the degradation of micro-arc-oxidized AZ31 magnesium aloy in the femoral condyle of rabbits based on micro-CT images and relative data. METHODS:Forty micro-arc-oxidized AZ31 magnesium aloys were implanted into the right femoral condyle of 40 New Zealand rabbits. Then 10 right femoral condyles were removed at 5, 10, 15 and 20 weeks after surgery, respectively, to quantitatively analyze and evaluate the degradation of AZ31 magnesium aloys by micro-CT images and relative data. RESULTS AND CONCLUSION:The surface of AZ31 aloys was corroded progressively with dark color and distorted appearance at 5-20 weeks post implantation. Micro-CT images showed that in the first 5 weeks, the degradation was inactive, and at the 10th week, it turned active; at the 15th week, the corrosion pits were obviously increased in number, and the corrosion area and corrosion speed were enlarged and fastened, respectively. Up to the 20th week, the aloy surfaces were ful of corrosion pits besides roughness and discontinuity. Relevant data analysis showed that the volume fraction of magnesium aloy was 98.6%, 97.1% and 86.4% at the 5th, 10th and 20th weeks after implantation, respectively, and it had a significant decrease from the 10th to 15th week and from the 15th to 20th week (P < 0.05). Within 15-20 weeks, the volume fraction of magnesium aloy was decreased by 6.5% that was the maximum volume reduction per unit cycle. With the progress of corrosion, the surface continuously became rough and vague, and its surface area was enlarged; the ratio of surface area to volume continuously increased, and there was a significant difference at 15 and 20 weeks (P < 0.05). Because of the increasing number of corrosion pits, the cross-sectional radius decreased, which was reflected by the trabecular thickness decreasing from 1.00 to 0.87 mm. From the view of the slope of curve, the trabecular thickness decreased most rapidly at 10-15 weeks. The mineral density of magnesium aloy continuously decreased from 649.302 to 356.445 mg/cm3 during the whole experiment period (P< 0.05). In addition, the micro-CT image density decreased from 679.710 to 644.947 mg/cm3, but there was no significant difference. To conclude, the degradation speed is peaked at 10-20 weeks after implantation, and the content of magnesium aloys decrease with degradation, but the magnesium density has no significant change.