92 / 2018-08-02 12:12:04

Polymer Coatings on Mg for Improving Human Endothelial Cell Adhesion and Spreading

Polymer,biodegradable,magnesium,cardiovascular stent,human umbilical vein endothelial cells

全体主题 > iv. Design and fabrication of organ-on-a-chip, disease models, bioreactors, and medical and diagnostic devices

Introduction
Magnesium (Mg) is promising for making bioresorbable cardiovascular stent due to its biodegradability and biocompatibility. However, despite of its satisfying safety profile in human test as a stent material1-3, Mg-based stent was found to have resulted in undesirable neointimal hyperplasia and abnormal endothelium activities1-3. In the present work, we introduced polymer coatings to modify the biological performances of Mg. We established a comparative model to investigate poly(L-lactic acid) (PLLA), two poly(lactic-co-glycolic acid) (PLGA) coatings and polycaprolactone (PCL) coating on Mg. The influences of different polymer coatings on the degradation of Mg and the adhesion and spreading of cells have been compared using direct culture method with human endothelial cells. The PLGA (50:50) coating can potentially stimulate endothelium recovery due to the improved cell adhesion, hence improving the currently used Mg-based stent. The mechanism behind has been further discussed.

Materials and methods
The fine-polished Mg chip was embedded in the chemically stable epoxy resin, leaving only one face exposed to the air. Four different polymer coatings were spin-coated onto the substrate of Mg with thickness of 0.5-2 μm.

The as-prepared polymer coatings were characterized using SEM. Their functions on controlling cells were evaluated using the direct culture of human umbilical vein endothelial cells (HUVECs) with the samples and controls.

Results
The morphologies of the four different polymer coatings have been characterized using SEM (Fig. 1)4. PLLA, PLGA (90:10) and PLGA (50:50) coatings demonstrated plain amorphous morphologies. PCL coating demonstrated crystalline morphology. The thickness of all polymer coatings was around 0.5-2 μm. The HUVEC direct culture (Fig. 2)4 indicated that the different polymer materials have differently influenced cell adhesion and spreading. PLGA (50:50)-coated Mg showed greatly more HUVECs attached on the surface than other groups.

Conclusions
PLLA and two PLGA coatings showed amorphous morphologies. PCL coating showed crystalline morphology. All the polymer coatings completely covered the surface of Mg substrate. PLGA (50:50) most greatly improved the adhesion and spreading of HUVECs, which is promising for further studies in animal model.

References
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2. Haude, M.; Ince, H.; Abizaid, A.; Toelg, R.; Lemos, P. A.; von Birgelen, C.; Christiansen, E. H.; Wijns, W.; Neumann, F.-J.; Kaiser, C., (2016) Safety and performance of the second-generation drug-eluting absorbable metal scaffold in patients with de-novo coronary artery lesions (BIOSOLVE-II): 6 month results of a prospective, multicentre, non-randomised, first-in-man trial. The Lancet 387 (10013), 31-39.
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