Sexual Slow-releasing Biodegradable Stents Lower Limb Ischemia Reascularization

Site-specific controlled release of exogenous, angiogenic growth factors such as recombinant human basic fibroblast growth factor (rhbFGF) has become a promising approach to improve ischemic heart disease or peripheral vascular disease. RhbFGF is unstable and the preparation process must be controlled strictively to maintain the bio-activity of rhbFGF. In the present study, we prepared a tubular stent composed by spiral magnesium (Mg) in the inner and a coating including a therapeutic agent rhbFGF and poly(lactic-co-glycolic acid)(PLGA) as matrix in the outer. We tested its effect on promoting angiogenesis in rat limb ischemic model.In vitro release studies showed that the model protein bovine serum albumin (BSA) was released continuously for4weeks. BSA was released75.29±1.33%from Mg-PLGA stent and54.73±2.89%from PLGA stent4weeks after immersion in phosphate buffered saline (PBS). Influence of different concentrations of Mg2+on the structure of BSA was investigated by ultraviolet-visible (UV-Vis) spectra, fluorescence spectra and circular dichroism (CD) spectra. Results indicated that the secondary structure of BSA was not influenced by the addition of Mg2+. The in vitro degradation study was processed. The corrosion morphology was observed by scanning electron microscopy (SEM). The degradation percentage and the pH of the solution were tested at predetermined time points.The in vitro cell experiments revealed that Mg-PLGA-rhbFGF stent had advantages over PLGA-rhbFGF stent on cytotoxicity, proliferation and migration. Rat limb ischemic model was build and stent was implanted into the adductor muscle after the creation of a mechanical channel.2,4and6weeks post stents implantation, muscle adjescent to the stent was retrieved for analysis. HE staining and CD31+immunostaining revealed that the controlled release of rhbFGF from Mg-PLGA-rhbFGF stent was superior in promoting angiogenesis to PLGA-rhbFGF stent.6weeks post stent implantation, the capillary density of Mg-PLGA-rhbFGF group was85.3±10.1(number/mm2), much higher to PLGA-rhbFGF group (71.0±5.6)(number/mm2) and control group (8.7±0.6)(number/mm2), p<0.01. What’s more, the limb blood perfusion ratio of Mg-PLGA-rhbFGF and PLGA-rhbFGF group were dramatically increased, with data99.08±0.029%and80.68±0.032%, respectively, whereas the ischemia limb didn’t recover in the control group. The concentrations of Mg2+were within normal range in the body fluid. Routine blood test and visceral pathology were conducted and no adverse effect was detected. The stents we prepared had good biocompatibility.Puerarin is a major effective isoflavonoids extracted from the traditional Chinese medicine Ge-gen (Radix Puerariae, RP). Puerarin has been used to treat patients with coronary artery diseases (CAD). Limited data related to the effect of puerarin on PVD were seen. In the previous study, the routes of administration of puerarin were focused up on intravenous, intraperitoneal injection or gavage administration. In this study, puerarin was encapsulated in the copolymer PLGA and the role of PLGA-puerarin on angiogenesis in rat limb ischemic model was tested. It was found that PLGA-puerarin induced angiogenesis and increased blood perfusion ratio in the rat ischemic limb. The gene expression or activation of endothelial nitric oxide synthase (eNOS), platelet derived growth factor-β (PDGF-β) and vascular endothelial growth factor (VEGF) that correlated with angiogenesis were with high expression in the muscle adjescent to the implanted PLGA-puerarin stent. The stents we prepared didn’t induce any hemolytic reaction. Routine blood test and visceral pathology were conducted and no adverse effect was detected. The stent we prepared had good biocompatibility. Wound healing study was conducted and results Indicated that puerarin had benefit effect on wound healing.RhbFGF loaded Mg-PLGA stent and puerarin loaded PLGA stent could promote angiogenesis of rat limb ischemia, and they may provide a theoretical basis for the critical ill patients suffered from lower limb ischemic disease. A novel nanoparticles (NPs)-based brain drug delivery system made of hyperbranched polyglycerol-conjugated poly (lactic-co-glycolic acid)(HPG-PLGA) which was surface functionalized with transferrin antibody (0X26) was prepared. HPG-PLGA was synthesized, characterized and applied to prepare NPs by means of double emulsion solvent evaporation technique. Transmission electron micrograph showed that NPs had a round and regular shape with a mean diameter of170±20nm. Surface chemical composition was detected by X-ray photoelectron spectroscopy. Endomorphins (EM), as a model drug, was encapsulated in the NPs. In vitro drug release study showed that EM was released continuously for72h. Cellular uptake study showed that the uptake of NPs by the brain microvascular endothelial cells was both time-and concentration-dependant. Further uptake inhibition study indicated that the uptake of NPs was via a caveolae-mediated endocytic pathway. In vivo EM brain delivery ability was evaluated based upon the rat model of chronic constriction injury of sciatic nerve.0X26modified NPs had achieved better analgesic effects, compared with other groups. Thus,0X26modified HPG-PLGA NPs may be a promising brain drug delivery carrier.