You protocol is fine. That's exactly what we use all the time. It might be the strain background you are using. Not sure if BT549 grow in NOD-SCID. Have you tried athymic or NSG?

Hi Richard

Thank you for your answer. Athymic nude mice are less immunocompromised than SCIDs, so I would as a baseline assume that if it could grow in nude mice, it could grow in SCID. But have you experienced otherwise? Which mice do you use?

Hi,

We have the same issue with the injection of BT549 cell line orthotopically into NOD/Scid mice. We didn't succeed to induce a tumour growth  while MDA-MB231 works perfectly well.

Eventually, did you succeed to obtain a primary tumour using this cell line? Thank you for your help. Did you try with another mouse strain?

Sabrina

Hi Sabrina

No, I did not succeed with obtaining tumors with BT549 cells, and as we breed our own NOD/SCIDs, I did not get to try with another strain. 

MDA-MB-231 and MCF7 (with estradiol supplements) works like a charm. Also H1299 and A549 orthotopic implantation works fine with NOD/SCID. 

But thank you for your answer. It is nice to know that others has experienced the same. 

Best wishes

Pernille

The expected take rate of BT549 cells in vivo can vary based on several factors, including the specific experimental conditions, the method of cell administration, the characteristics of the host animal, and the biological behavior of the BT549 cell line. Here’s a general overview of what to consider:

**1. About BT549 Cells

**1.1 Characteristics:

Origin: BT549 cells are a human breast cancer cell line derived from a metastatic breast tumor.

Properties: They are known for their aggressive growth and ability to form tumors in vivo.

**2. Factors Affecting Take Rate

**2.1 Cell Injection Method:

Orthotopic Injection: Implanting cells directly into the mammary fat pad of the animal, which is the most relevant model for breast cancer.

Subcutaneous Injection: Injecting cells into the flank of the animal, which is a more convenient method but less representative of natural tumor growth.

**2.2 Animal Model:

Immunocompromised Mice: Using strains like nude or SCID mice that lack functional immune systems, which improves the likelihood of successful tumor take.

Genetic Background: Different strains of mice may have varying levels of susceptibility to tumor growth.

**2.3 Cell Number and Viability:

Injection Dose: The number of cells injected can influence the take rate. Typically, a higher number of cells increases the likelihood of successful tumor establishment.

Cell Viability: Ensuring that the cells are in good condition before injection is crucial for a successful take rate.

**2.4 Tumor Microenvironment:

Supportive Environment: Factors such as the presence of growth factors, extracellular matrix components, and blood supply can affect tumor establishment.

**3. Expected Take Rate

**3.1 General Take Rates:

Orthotopic Injection: For BT549 cells injected orthotopically, the take rate can vary but often ranges from 60% to 90%, depending on the experimental conditions.

Subcutaneous Injection: The take rate for subcutaneous injections is usually high, often approaching 80% to 100%, due to the less complex environment compared to orthotopic models.

**3.2 Variability:

Experimental Conditions: Variations in experimental protocols, cell preparation, and animal health can lead to differences in take rates.

**4. Optimizing Take Rate

**4.1 Cell Preparation:

Use Fresh Cells: Use freshly prepared, high-quality cells to improve the likelihood of successful tumor take.

Proper Storage: Avoid multiple freeze-thaw cycles as they can reduce cell viability.

**4.2 Injection Technique:

Accuracy: Ensure precise and sterile injection techniques to minimize cell loss and contamination.

**4.3 Monitoring and Support:

Regular Monitoring: Monitor the animals for tumor growth and health to assess take rates and overall experimental success.

Summary

The take rate of BT549 cells in vivo can be high, especially when using immunocompromised mice and optimizing experimental conditions. Orthotopic injections typically have a slightly lower take rate compared to subcutaneous injections, but provide a more physiologically relevant model. Ensuring high cell viability and proper injection techniques can help achieve optimal take rates.

l Reviewing the protocols listed here may offer further guidance in addressing this issue.