Absorbable magnesium-based stent: physiological factors to consider for in vitro degradation assessments

Absorbable metals have been widely tested in various in vitro settings using cells to evaluate their possible suitability as an implant material.However,there exists a gap between in vivo and in vitro test results for absorbable materials.A lot of traditional in vitro assessments for permanent materials are no longer applicable to absorbable metallic implants.A key step is to identify and test the relevant microenvironment and parameters in test systems,which should be adapted according to the specific application.New test methods are necessary to reduce the difference between in vivo and in vitro test results and provide more accurate information to better understand absorbable metallic implants.In this investigative review,we strive to summarize the latest test methods for characterizing absorbable magnesium-based stent for bioabsorption/biodegradation behavior in the mimicking vascular environments.Also,this article comprehensively discusses the direction of test standardization for absorbable stents to paint a more accurate picture of the in vivo condition around implants to determine the most important parameters and their dynamic interactions.

Magnesium incorporated chitosan based scaffolds for tissue engineering applications

Chitosan based porous scaffolds are of great interest in biomedical applications especially in tissue engineering because of their excellent biocompatibility in vivo,controllable degradation rate and tailorable mechanical properties.This paper presents a study of the fabrication and characterization of bioactive scaffolds made of chitosan(CS),carboxymethyl chitosan(CMC)and magnesium gluconate(MgG).Scaffolds were fabricated by subsequent freezing-induced phase separation and lyophilization of polyelectrolyte complexes of CS,CMC and MgG.The scaffolds possess uniform porosity with highly interconnected pores of 50-250 μm size range.Compressive strengths up to 400 kPa,and elastic moduli up to 5 MPa were obtained.The scaffolds were found to remain intact,retaining their original threedimensional frameworks while testing in in-vitro conditions.These scaffolds exhibited no cytotoxicity to 3T3 fibroblast and osteoblast cells.These observations demonstrate the efficacy of this new approach to preparing scaffold materials suitable for tissue engineering applications.