Objective: To evaluate the effectiveness of poly (lactic-co-glycolic acid) (PLGA) nanofiber membrane on prevention of postoperative abdominal adhesion. Methods: PLGA nanofiber membrane was prepared by high-voltage electrospinning technique. The effectiveness of the membrane in prevention of postoperative abdominal adhesions was characterized with rat abdominal adhesion models. Results: PLGA nanofiber membrane was prepared successfully by electrospinning technique. Scanning electron microscopy (SEM) observation showed that the average diameter of PLGA fibers was approximately 800 nm, and the membrane had microporous structures. Mechanical tests showed that the tensile strength of PLGA nanofiber membrane was 6.36 ± 0.39 MPa, which was significantly higher than the tensile strength of DIKANG absorbable medical film. The results of in vivo experiments showed that PLGA nanofiber membrane and DIKANG absorbable medical film could both reduce the degree of abdominal adhesions. The histological results showed that there was only a small extent of inflammatory cell infiltration in the PLGA group and the control group. The proliferation of connective tissue was reduced, and so was the degree of adhesion. Conclusion: PLGA nanofiber membrane can significantly reduce the incidence and severity of postoperative adhesions, and bodes well for future clinical applications.

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This study reports the encapsulation of vancomycin, as a model hydrophilic drug, into poly(lactide-co-glycolide) microspheres using a novel reformative shear precipitation procedure. In contrast to the external aqueous phase used in the conventional microencapsulation technique based on emulsion solvent evaporation/extraction, the reformative shear precipitation procedure explored in this study uses a shear medium composed of glycerol as the viscous medium and ethanol as polymer antisolvent, which is relatively immiscible with the hydrophilic drug. This limits drug diffusion and leads to rapid microsphere solidification, which allows a large proportion of the hydrophilic drug to be encapsulated within the microspheres. The influence of various processing parameters, including polymer concentration, volume ratio of ethanol to glycerol in the shear medium, volume of aqueous drug solution, initial drug loading, and injecting rate of the drug-polymer emulsion, on the encapsulation efficiency and characteristics of resulting microspheres were investigated. The morphology and release characteristics, as well as mechanical, in vitro and in vivo behaviour of vancomycin-loaded poly(lactide-co-glycolide) microspheres prepared using the novel procedure were also investigated. The results demonstrated that the reformative shear precipitation procedure could achieve the loading of hydrophilic drugs into poly(lactide-co-glycolide) microspheres with high encapsulation efficiency, and the success of the procedure was largely influenced by the volume ratio of ethanol to glycerol in the shear medium. Vancomycin-loaded poly(lactide-co-glycolide) microspheres prepared using this procedure demonstrated favourable mechanical characteristics, antibacterial activity, and in vivo degradation behaviour which suggested their suitability for use as a sustained delivery system.

Right ventricular outflow tract (RVOT) reconstruction is a common surgical method to treat congenital cardiac lesions, and bovine jugular vein conduit (BJVC) has become a prevalent candidate of prosthetic material for this procedure since 1999. Although many clinical studies have shown encouraging results on BJVCs, complications such as stenosis, aneurysmal dilatation, valve insufficiency, and infective endocarditis revealed in other clinical outcomes still remain problematic. This review describes the underlying mechanisms causing respective complications, and summarizes the current technological development that may address those causative factors. Novel crosslinking agents, decellularization techniques, conduit coatings, and physical reinforcement materials have improved the performances of BJVCs. The authors expect that the breakthroughs in the clinical application of BJVC may come from new genetic research findings and advanced characterization apparatuses and bioreactors, and are optimistic that the BJVC will in the future provide sophisticated therapies for next-generation RVOT reconstruction.

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