In-vitro dissolution characteristics and human adipose stem cell response to novel borophosphate glasses

The main drawbacks of traditional silicate bioactive glasses are their narrow hot forming domain and noncongruent dissolution. In this article, we report on new borophosphate glasses [xM_nO_m + (100 − x) (47.5P₂O₅ + 2.5B₂O₃ + 10Na₂O + 20CaO + 20SrO)], M_nO_m being CuO, Ag₂O, and CeO₂, having high thermal processability, hence suitable for fiber drawing and sintering into scaffolds. Furthermore, the glasses dissolve congruently in simulated body fluid (SBF) and TRIS buffer solution, eventually leading to the precipitation of a reactive layer. Human adipose stem cells (hASC) were cultured in media enriched with glass extract at different dilutions, to investigate the optimal ion concentration for cell survival. Cells grew in all the extracts, except in the undiluted Cu-doped glass extract. At dilution 1:10, the lactate dehydrogenase (LDH) activity and cell proliferation were comparable to the control, while at 1:100, the cells proliferated faster than the control. Thus, the reference (undoped), Ag and Ce-doped glasses were found to be suitable for cell viability and proliferation. Cytotoxicity assessments using the LDH assay indeed revealed the high cytotoxicity of the Cu extract. This raises questions about the use of Cu in bioactive glasses and its optimal concentration as a dopant.