In vitro degradation of four magnesium–zinc–strontium alloys and their cytocompatibility with human embryonic stem cells
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Magnesium alloys have attracted great interest for medical applications due to their unique biodegradable capability and desirable mechanical properties. When designed for medical applications, these alloys must have suitable degradation properties, i.e., their degradation rate should not exceed the rate at which the degradation products can be excreted from the body. Cellular responses and tissue integration around the Mg-based implants are critical for clinical success. Four magnesium–zinc–strontium (ZSr41) alloys were developed in this study. The degradation properties of the ZSr41 alloys and their cytocompatibility were studied using an in vitro human embryonic stem cell (hESC) model due to the greater sensitivity of hESCs to known toxicants which allows to potentially detect toxicological effects of new biomaterials at an early stage. Four distinct ZSr41 alloys with 4 wt% zinc and a series of strontium compositions (0.15, 0.5, 1, and 1.5 wt% Sr) were produced through metallurgical processing. Their degradation was characterized by measuring total mass loss of samples and pH change in the cell culture media. The concentration of Mg ions released from ZSr41 alloy into the cell culture media was analyzed using inductively coupled plasma atomic emission spectroscopy. Surface microstructure and composition before and after culturing with hESCs were characterized using field emission scanning electron microscopy and energy dispersive X-ray spectroscopy. Pure Mg was used as a control during cell culture studies. Results indicated that the Mg–Zn–Sr alloy with 0.15 wt% Sr provided slower degradation and improved cytocompatibility as compared with pure Mg control.
KeywordsSlow Degradation Improve Cell Viability Standard Cell Culture Condition Bioabsorbable Polymer hESC Coloni
The authors would like to thank the U.S.A. NSF BRIGE award (CBET 1125801), Burroughs Welcome Fund (1011235), Hellman Fellowship, and the University of California Regents Faculty Fellowship for financial support. The authors also thank National Natural Science Foundation of China (Grant 51034002, 50974038 and 51074049) and the Fok Ying Tong Education Foundation (132002) for financial support. The authors thank the Central Facility for Advanced Microscopy and Microanalysis (CFAMM) and the Stem Cell Center (Drs. Prudence Talbot and Duncan Liew) at the University of California, Riverside.
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