dr3amxstar

My lab purchased Human cardiac myocytes cryopreserved cells and the order arrived a few months back. Since then, I have been trying to grow and passage it to no avail. At the start, it took only 3 days for the T25 to reach 80% confluency. Subsequently, the flasks is very prone to contamination and i have to regrow it from vials that i freeze down whenever it got contaminated. whenever i tried to passage it from one T25 flask out to 2 T25 flask, either both flask got contaminated or one of the flask(Flask A) got contaminated while the other flask (Flask B) remains fine. For flask B, it have been 10 days but yet the flask is not even 70% confluence. While culturing HCM, protocol given by the supplier were strictly followed. Everything is being done in the hood. I did culture different cell lines before and did not encounter such problem before. I am quite stuck not being unable to proceed with my experiments and i have a very tight timeline. Do advise if anyone have any idea what is contributing to this problem. Thank you very much!