Hi everyone, I'm currently working on bone-targeting polymeric nanoparticles for treatment of osteoporosis. Just wondering what kind of human osteoblast (or other bone cells) are best suitable for the cytotoxicity test. I've bought primary human osteoblast from sigma but found it growing extremely slowly. I've also tried MG-63 cells but it was criticised as a cancer cell (not suitable for examination of nanoparticles cytotoxicity). Is there a human osteoblast cell line that is not cancer cells and growing fast? Could anyone give me a clue? Thank you very much!