Cotton wool-like nanocomposite biomaterials prepared by electrospinning: in vitro bioactivity and osteogenic differentiation of human mesenchymal stem cells

The present study evaluates the in vitro biomedical performance of an electrospun, flexible, and cotton wool-like poly(lactide-co-glycolide) (PLGA)/amorphous tricalcium phosphate (ATCP) nanocomposite. Experiments on in vitro biomineralization, applicability in model defects and a cell culture study with human mesenchymal stem cells (hMSC) allowed assessing the application of the material for potential use as a bone graft. Scaffolds with different flame made ATCP nanoparticle loadings were prepared by electrospinning of a PLGA-based composite. Immersion in simulated body fluid showed significant deposition of a hydroxyapatite layer only on the surface of ATCP doped PLGA (up to 175% mass gain within 15 days for PLGA/ATCP 60:40). Proliferation and osteogenic differentiation of hMSC on different nanocomposites were assessed by incubating cells in osteogenic medium for 4 weeks. Proper adhesion and an unaffected morphology of the cells were observed by confocal laser scanning microscopy for all samples. Fluorometric quantification of dsDNA and analysis of ALP activity revealed no significant difference between the tested scaffolds and excluded any acute cytotoxic effects of the nanoparticles. The osteocalcin content for all scaffolds was 0.12-0.19 ng/ng DNA confirming osteogenic differentiation of human mesenchymal stem cells on these flexible bone implants.