PLGA+HA/βTCP Scaffold Incorporating Simvastatin: A Promising Biomaterial for Bone Tissue Engineering
The aim of this study was to synthesize, characterize, and evaluate degradation and biocompatibility of poly(lactic-co-glycolic acid) + hydroxyapatite/β-tricalcium phosphate (PLGA+HA/βTCP) scaffolds incorporating simvastatin (SIM) to verify if this biomaterial might be promising for bone tissue engineering. Samples were obtained by the solvent evaporation technique. Biphasic ceramic particles (70% HA, 30% βTCP) were added to PLGA in a ratio of 1:1. Samples with SIM received 1% (m/m) of this medication. Scaffolds were synthesized in a cylindric shape and sterilized by ethylene oxide. For degradation analysis, samples were immersed in phosphate-buffered saline at 37°C under constant stirring for 7, 14, 21, and 28 days. Nondegraded samples were taken as reference. Mass variation, scanning electron microscopy, porosity analysis, Fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetry were performed to evaluate physico-chemical properties. Wettability and cytotoxicity tests were conducted to evaluate the biocompatibility. Microscopic images revealed the presence of macro-, meso-, and micropores in the polymer structure with HA/βTCP particles homogeneously dispersed. Chemical and thermal analyses presented similar results for both PLGA+HA/βTCP and PLGA+HA/βTCP+SIM. The incorporation of simvastatin improved the hydrophilicity of scaffolds. Additionally, PLGA+HA/βTCP and PLGA+HA/βTCP+SIM scaffolds were biocompatible for osteoblasts and mesenchymal stem cells. In summary, PLGA+HA/βTCP scaffolds incorporating simvastatin presented adequate structural, chemical, thermal, and biological properties for bone tissue engineering.
(a) Mass variation of scaffolds (g) at different time points; error bars represent standard deviation. Results were compared among different experimental time evaluating each group separately. Different letters refer to statistical difference (ANOVA/Tukey, P < .05). (b) Porosity [cm2 (±standard deviation)] for scaffolds at days 0, 7, 14, 21, and 28. Results were compared between groups evaluating each experimental time separately. *Significant difference between groups (t test, P < .05). PLGA indicates poly(lactic-co-glycolic acid); HA, hydroxyapatite; βTCP, β-tricalcium phosphate; SIM, simvastatin.
Scanning electron microscopy for samples with no simvastatin (SIM) and with SIM in ×50 and ×1000 magnification at days 0, 7, and 28. Purple and green arrows indicate the polymer and the ceramic structures, respectively. Dashed lines differentiate the micro (yellow), meso (pink), and macro (blue) porous. PLGA indicates poly(lactic-co-glycolic acid); HA, hydroxyapatite; βTCP, β-tricalcium phosphate; SIM, simvastatin.
(a) Fourier transform infrared spectroscopy graphs for samples with no simvastatin (SIM) and with SIM at days 0, 7, 14, 21, and 28. (b) Chart shows absorption bands and their correspondences according to the existing literature. PLGA indicates poly(lactic-co-glycolic acid); HA, hydroxyapatite; βTCP, β-tricalcium phosphate.
(a) Differential scanning calorimetry (DSC) and (b) thermogravimetry graphs for samples with no simvastatin (SIM) and with SIM at 0, 7, 14, 21, and 28 experimental days. PLGA indicates poly(lactic-co-glycolic acid); HA, hydroxyapatite; βTCP, β-tricalcium phosphate; TGA, mass loss; DrTGA, derivative of the mass loss.
Wettability analysis showing the samples without simvastatin (a and b) and with simvastatin (c and d). (a and c) Images were taken immediately after positioning the drop, whereas (b and d) these images were taken 1 hour after drop deposition.
Cytotoxicity analyses on preosteoblasts MC3T3-E1 and stem cells from human exfoliated deciduous teeth at days 1, 3, and 7. The percentages of viable cells were calculated in relation to the positive control (100%). Error bars represent standard deviation. Results were compared among groups evaluating each experimental time separately. Different letters refer to statistical difference (ANOVA/Tukey, P < .05). PLGA indicates poly(lactic-co-glycolic acid); HA, hydroxyapatite; βTCP, β-tricalcium phosphate; SIM, simvastatin.
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