Hello,
I am testing the effect of pharmaceuticals against estrogen responsive breast cancer - using MCF7 cells in NOD SCID IL2RGnull mice.
I transplant usually an estrogen releasing pellet under the skin of the mice and 3 d later inject s.c. 5 million cells on the flank. After a week I have palpable masses, that initially grow fast, than much slower if not anymore..... could it be that the pellet doesn't work like it should ?
I heard about cachexia, but could I avoid that ?
Thanks for any suggestion
We do flank injections with 1 million cells into immunodeficient mice (http://altogenlabs.com/xenograft-models/breast-cancer-xenograft/mcf7-xenograft-model/). The estrogen pellet is helpful. You haven't given many details about the overall growth curve, so it's difficult to pinpoint possible sources of error. If you contact us directly with more details we'd be glad to help. MCF-7 xenografts are fairly common, but having experience with them is gonna be necessary for precise studies.
For MCF7 xenografts, the NSG mice you are using are the best model.
However, flank tumors are not preferred in the field.
Mamamary Fat Pad injections using the Brill method , or the MIND model are more useful.
Article A Preclinical Model for ERa-Positive Breast Cancer Points to...
We have used athymic nude mice 8 weeks old and 3-4 million cells which worked nicely.
Nudes can have serious toxicity issues with estrogen pellets, if i recall correctly.
Thanks to both,
@ JAmes: a collaborator of our group uses also nude mice and they are quite content. They inject 5 million cells. So do I in my NOD SCID mice.
I just put the pellet on the flank instead of the neck, but I got told it is not a problem as long as s.c.
Do you have any suggestion ?
And I was just worried, because the masses developed pretty fast in the first 10 days : they reached all between 4x4mm til 6.5x7mm and then they kinda stopped growing (in my CTR-group) ...
but now, after 24 days post injection, they seem to grow again
@Vanessa:
It depends on the question you are asking.
Subcutaneous mammary xenograft growth models are initially not restrained by extracelluar context and grow quite quickly. After a certain volume, non-invasive tumors will be contrained by space, blood supply, and ECM composition. When tumors reach this barrier their phenotype may change or not depending on cell type/aggressiveness.
-as a contrast to MCF-7, MDA-MB-231 will usually grow uncontrolled in subcutaneous models.
Mammary Fat Pad xenograft (orthotopic) models are thought to be more relevant for mammary cancer growth because of basement membrane constraints and the presence of most of the cell types a mammary tumor would encounter in a human. In these studies, tumors tend to grow more slowly and steadily. However, there are some important caveats:
1. Human mammary tissue is denser, more fibroblastic, and has much higher Col1 content than the mouse mammary gland. This is purportedly why many mammary PDX tumors grow better in subcutaneous models where the skin of the mouse has ample Col1 and fibroblastic contribution. @kuppusamy may be able to comment better on that.
2. Mammary tumors initially grow and fill in the ductal tree before becoming invasive and entering into the stromal compartment. In the fatpad model, cells are injected directly into the adipose tissue, which may not be appropriate for lower grade tumors. This is debatable.
I hope that information helps. In the end the choice of models is your decision, based on your expected outcomes and experimental design, which is the art of science !
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