Hello Federica Prosperi

If you are planning to store the bone marrow cells after femoral flushing with PBS, then I would recommend the use of cryoprotectant like DMSO to freeze the bone marrow cells. You may flush the marrow, spin and resuspend them in 95% FBS + 5 % DMSO. You may store these cells in cryovials and place them in liquid nitrogen (typically -196°C). Storing in liquid nitrogen will significantly extend storage duration and preserve cell integrity better than -80°C.

Do not freeze the femur at -80°C because bone marrow cells are indeed sensitive and cannot be effectively flushed out of a femur after it has been frozen at -80°C. Freezing disrupts the delicate cellular structure of the bone marrow, making it difficult to isolate viable cells later.

Best,