Nude mice, also known as athymic mice, are a unique strain of laboratory mice characterized by a genetic mutation that results in the absence of a functional thymus, leading to a severely compromised immune system. This makes them invaluable in biomedical research, particularly in studies involving xenografts, cancer research, and immunology. Below is a detailed explanation of how nude mice are produced and their applications in bioresearch.

1. Production of Nude Mice

Nude mice are produced through selective breeding and genetic manipulation. The key genetic mutation responsible for their phenotype is in the FOXN1 gene, which is critical for thymus development and hair growth. Here’s how they are produced: 

Genetic Basis: The mutation in the FOXN1 gene (denoted as nu/nu) leads to the absence of a thymus, resulting in a lack of mature T cells and a compromised adaptive immune system. This mutation also causes the characteristic hairless phenotype. Breeding Strategy: Nude mice are typically bred by crossing homozygous nude males (nu/nu) with heterozygous females (nu/+). This breeding strategy ensures that approximately 50% of the offspring will be nude mice (nu/nu), while the other half will be heterozygous (nu/+) with normal thymus function. Housing and Care: Due to their immunodeficient nature, nude mice require specific pathogen-free (SPF) environments to prevent infections. They are housed in sterile conditions with strict biosecurity measures, including the use of personal protective equipment (PPE) and regular sanitization of cages and facilities.

2. Applications in Bioresearch

Nude mice are widely used in biomedical research due to their unique immunological characteristics. Below are their primary applications:

A. Cancer Research Xenograft Models: Nude mice are extensively used for transplanting human tumor cells or tissues (xenografts) to study tumor growth, metastasis, and the efficacy of anticancer therapies. Their lack of T cells prevents graft rejection, making them ideal for such studies. Drug Testing: They serve as a model for evaluating the safety and efficacy of new cancer drugs, including chemotherapy and immunotherapy agents. Tumor growth rates and responses to treatment can be monitored in vivo.

B. Immunology Studies Immune System Research: Nude mice are used to study the role of T cells in immune responses, as they lack mature T cells but retain other immune components like B cells, natural killer (NK) cells, and macrophages. Humanized Mouse Models: By transplanting human immune cells or tissues into nude mice, researchers can create "humanized" models to study human immune responses, autoimmune diseases, and infectious diseases like HIV C. Transplantation Studies

Tissue and Organ Grafts: Nude mice can accept grafts from other species, including human tissues, making them useful for studying tissue compatibility, graft survival, and regenerative medicine.

Stem Cell Research: They are used to study the differentiation and function of human stem cells in vivo, providing insights into stem cell therapy and tissue engineering.

D. Infectious Disease Research Pathogen Studies: Due to their immunodeficient state, nude mice are used to study the pathogenesis of infectious diseases and the efficacy of vaccines or antiviral drugs. In Vivo Imaging Fluorescence and Bioluminescence Imaging: Nude mice are often used in imaging studies to track tumor growth or the distribution of therapeutic agents in real-time, thanks to their hairless phenotype, which facilitates clear imaging.

3. Challenges and Considerations

While nude mice are highly valuable in research, there are some challenges: Fragile Health: Their immunodeficient nature makes them susceptible to infections, requiring stringent SPF conditions. Limited Lifespan: Nude mice typically have a shorter lifespan (6–12 months) compared to normal mice, which can limit long-term studies. Variability in Tumor Take Rates: Not all human tumors successfully grow in nude mice, and tumor take rates can vary depending on the tumor type and inoculation site.

4. Conclusion

Nude mice are a cornerstone of biomedical research, particularly in cancer, immunology, and transplantation studies. Their unique genetic makeup and immunodeficient phenotype enable researchers to conduct experiments that would be impossible in immunocompetent models. However, their care requires meticulous attention to hygiene and experimental controls to ensure reliable and reproducible results.

For further details, you can refer to the sources cited above, such as Zistbalin technical group , which provide comprehensive information on nude mice and their applications.