we usually use 8 weeks old so 10 weeks isn't totally out of the ball park. If you have no other choice Id say It would be fine. They wont be too old to form tumours, remember the older you get the more likely you are to get a tumour :)

I have worked with 8-10 weeks old mice and had no problem with the cell growth. Had no problem.

It depends on the strain of the mice you use for the transplantation experiments. In the case of the xenograft model with nude mice, for example, there is no problem in using 8-10 weeks of age. I would like to know whether you would perform the subcutaneous injection of the tumor cells or the orthotopic  transplantation experiment (e.g. to inject PANC1 cells to the pancreas). Orthotopic transplantation requires some of the aged mice the organs and tissues of which are well-sized enough.

I worked with Balb-C and C3H HeN , and tumor cells are CT 26 and CL-62-K1735 all mice grow subcutaneous cells when 10 years old

You should not have a problem with athymic nude mice for xenografts at 8 - 10 weeks of age. However, as these mice get older they become less tolerant of xeno-transplants. Typically, orthotopic implants will provide a better take than heterotopic (typically subcutaneous) injections. Also, if you use SCID or NOD-SCID mice, you will improve the take. NOD-SCID have dysfunctional T & B cell and NK cell function.

The websites of the Jackson Laboratories ( https://www.jax.org/strain/001303 ) or Charles River (  http://www.criver.com/products-services/basic-research/find-a-model/nod-scid-mouse ) provide detailled background information and references.

Anton Wellstein -Georgetown University, Lombardi Cancer Center

[email protected]

if your old mice more easier to form tumor, you will find something big, because it is human did.