Response to the letter age and site should be considered when investigating the effect of growth factors on human bone-derived cells

摘要

Thank you Dr. Chen and colleagues for your interesting letter discussing age and bone site-specific osteoblast responses to growth factors, and for citing previous literature that deals with the same topic. We are pleased that you read our article and were inspired to write to the editor. In your letter, you have stated that "it is inappropriate to choose neonatal mice to decide the concentration of growth factors applied to young and older human bone cells" and suggest "it would be more persuasive and compatible to change the neonatal mice into young and old mice to testify the best concentration." In fact, we agree with you, and therefore we did test various doses in cells from bones of young (2 months old) and old (19-22 months old) mice and reported that data in figure 1 of our manuscript (1). Furthermore, since we are aware of some differences between human and mouse cell response to fibroblast growth factor-2 (FGF-2) (2), we utilized the results from those human cell studies to determine the best dose of FGF-2 for the human cell studies in this manuscript rather than using the mouse data. We apologize if the wording was not clear and caused confusion.