Subcutaneous solid tumor model

Subcutaneous Xenograft Tumor Model

Introduction
The subcutaneous tumor model is one of the most widely used in vivo models in tumor research. It simulates the growth process of solid tumors by inoculating tumor cells (or tissue blocks) from human or animal sources into the subcutaneous tissue of immunodeficient mice. This model is simple to operate and has a high tumor formation rate. It is often used in anti-tumor drug screening, tumor biological mechanism research, and tumor imaging evaluation.

1. Selection of experimental animals

Common animals :

Nude mice (BALB/c nude) : T cell defective, suitable for human tumor cell transplantation.

NOD/SCID or NSG mice : Combined deficiency of B, T, and NK cells leads to a higher tumor formation rate (especially for low-invasive tumor cells).

Strain requirements :

4-6 weeks old, weighing 18-22g (mice), must be raised in an SPF (specific pathogen-free) environment.

2. Tumor Cell Line Selection

Commonly used human tumor cell lines :

Cell Requirements :

Cell viability>90% (trypan blue assay);

Conduct mycoplasma testing in advance;

It is recommended to use low passage number (passage number < 20).

3. Model building steps

Cell suspension preparation :

Tumor cells in the logarithmic growth phase were collected and resuspended in PBS or serum-free medium;

Adjust the cell density to 1×10⁶ ~ 1×10⁷ cells/mL （ Adjust according to cell type).

Vaccination method :

Single cell suspension injection :

Injection site: subcutaneous in the back or armpit of mice (avoid blood vessels and nerves);

Injection volume: 100-200 μL/mouse (containing 1×10⁶ ~ 5 × 10⁶ cells);

Using 25G ~ Inject slowly with a 27G needle to avoid leakage.

Tissue block transplantation (Applicable to primary tumors):

Cut fresh tumor tissue into 1-2 mm³ pieces;

The mouse was implanted subcutaneously using a trocar.

Tumor formation cycle monitoring :

After vaccination 3-7 days Palpable nodules began to appear; the long diameter (L) and short diameter (W) of the tumor were measured with a vernier caliper every 2-3 days, and the volume was calculated: tumor volume (mm ³ ) = L × W ² /2

General tumor formation standard: When the tumor volume reaches 100-200 mm³, it enters the experimental treatment stage.

Experimental endpoint processing :

When the tumor volume is greater than 2000 mm³ or the animal is in obvious pain, it should be humanely killed;

After autopsy, the tumor was weighed and the tumor inhibition rate was calculated: tumor inhibition rate (%) = (1-average tumor weight of the control group average tumor weight of the treatment group) × 100%

4. Advantages and disadvantages of the model

5. Notes

Cell state : Avoid using over-passaged or contaminated cells.

Inoculation site : Prioritize the subcutaneous area of ​​the back with rich blood supply.

Animal strains : For cells with low tumorigenicity (such as MCF-7), it is recommended to use NSG mice or mix with Matrigel (ratio 1:1) during inoculation.

Code of Ethics : The tumor volume does not exceed 10% of the animal's body weight (e.g., for a 20 g mouse, the tumor is ≤2000 mm³);

Approval from the Experimental Animal Ethics Committee is required.

6. Application Scenarios

Anti-tumor drug screening : Evaluate the efficacy of chemotherapy drugs, targeted drugs, and immune checkpoint inhibitors.

Study on the mechanism of tumor growth : Such as angiogenesis and metabolic reprogramming.

Radiographic evaluation : Dynamically monitor tumor progression through in vivo fluorescence (such as GFP/RFP labeling) or bioluminescence imaging.

Combination therapy strategies : In vivo validation of radiosensitizers and nanodrug delivery systems.

Sample Data