Hello ! I'm trying to obtain M2 polarized macrophages from freshly isolated rat BM-MNC by initial treatment with M-CSF and then with IL-4. I believe freshly isolated BM-MNC are not able to attach to the flask (that's why I transferred them 1 day after isolation to a new flask) but I am wondering when during this process of differentiation these cells will become able to attach to the culture flask ?