ID8 Syngeneic Model Overview

The ID8 syngeneic model is a murine ovarian carcinoma system derived from the C57BL/6 mouse strain and represents the most widely utilized preclinical platform for studying epithelial ovarian cancer in an immunocompetent setting. This model recapitulates the histopathological, molecular, and immunological characteristics of high-grade serous ovarian carcinoma (HGSOC) in humans. Its versatility, including both intraperitoneal and subcutaneous implantation routes, allows for evaluation of peritoneal dissemination, ascites formation, and immunotherapy response.

ID8 tumors develop gradually, forming ascitic fluid containing malignant epithelial cells and immune components. This model provides a clinically relevant system for investigating tumor–immune interactions, immune checkpoint blockade, adoptive cell therapies, and targeted therapeutics designed to treat ovarian cancer in a physiologically representative microenvironment.

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Biological and Molecular Characteristics

The ID8 cell line was established from spontaneously transformed ovarian surface epithelial cells of C57BL/6 mice. These cells exhibit epithelial morphology and express key ovarian carcinoma markers, including cytokeratin, E-cadherin, and Wilms’ tumor protein (WT1). Molecular profiling reveals activation of PI3K-AKT, STAT3, and TGF-beta signaling pathways, all of which are central to tumor proliferation, immune suppression, and metastatic progression.

Genetically modified ID8 derivatives (such as ID8-VEGF, ID8-p53−/−, and ID8-C3−/−) have expanded the model’s utility, enabling investigation of angiogenesis, immune evasion, and DNA repair mechanisms. The tumor microenvironment is immunosuppressive, enriched in tumor-associated macrophages (TAMs), myeloid-derived suppressor cells (MDSCs), and regulatory T cells (Tregs), which collectively mirror the immune landscape of advanced human ovarian carcinoma.

Parameter	Description
Host strain	C57BL/6 (female, 6–8 weeks)
Tumor origin	Spontaneously transformed ovarian surface epithelial cells (mouse)
Histological type	Epithelial ovarian carcinoma (high-grade serous–like)
Inoculation route	Intraperitoneal or subcutaneous
Tumor take rate	>90%
Doubling time	Approximately 5–7 days in vivo
Metastatic potential	High; peritoneal spread and ascites formation
Immunophenotype	E-cadherin⁺, WT1⁺, cytokeratin⁺, PD-L1⁺
Common applications	Immunotherapy, ovarian cancer research, cytokine studies, ascites modeling

In Vivo Model Development and Tumorigenicity

The ID8 model is typically established through intraperitoneal injection of tumor cells into immunocompetent C57BL/6 mice, leading to the development of peritoneal carcinomatosis and ascites accumulation over 6–10 weeks. Alternatively, subcutaneous implantation allows for easier tumor measurement and pharmacologic assessment while maintaining the model’s immunocompetence. Tumor growth is gradual yet highly consistent, producing reproducible disease kinetics suitable for long-term studies.

The model accurately simulates human ovarian cancer progression, including widespread peritoneal dissemination, omental nodules, and accumulation of malignant ascites containing tumor cells, macrophages, and T cells. Due to its robust immune microenvironment, ID8 is particularly suited for evaluating immune checkpoint inhibitors, adoptive T-cell therapies, and combinatorial regimens involving cytokines or anti-angiogenic agents. The model’s adaptability across implantation routes provides flexibility for efficacy testing, mechanistic research, and immune profiling.

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Histopathology and Immunohistochemical Profile

Histopathological analysis of ID8 tumors reveals papillary and glandular structures composed of epithelial cells with large nuclei, prominent nucleoli, and a high mitotic index. In the peritoneal form, tumors attach to mesothelial surfaces and invade the omentum and visceral organs, mimicking metastatic ovarian carcinoma. Ascitic fluid typically contains clusters of tumor cells, immune infiltrates, and inflammatory cytokines.

Immunohistochemical staining demonstrates strong expression of cytokeratin, E-cadherin, and WT1, confirming epithelial and ovarian origin. Ki-67 labeling indicates high proliferative activity, and CD31 highlights the dense vascular network supporting tumor growth. PD-L1 is moderately expressed and upregulated following cytokine stimulation or immunotherapy. Immune cell profiling identifies abundant F4/80-positive macrophages, Gr-1-positive myeloid cells, and CD3-positive T lymphocytes, consistent with an immunosuppressive but responsive tumor microenvironment.

Preclinical Applications and Drug Response

The ID8 syngeneic model has become the standard immunocompetent system for preclinical ovarian cancer studies. It has been extensively used to evaluate checkpoint inhibitors (anti-PD-1, anti-PD-L1, and anti-CTLA-4), cytokine therapies, and adoptive T-cell transfers. ID8 tumors respond to combinatorial regimens that integrate immune stimulation with chemotherapy or anti-angiogenic therapy.

The model’s well-defined immune environment makes it ideal for studying macrophage reprogramming, T-cell exhaustion, and mechanisms of immune evasion. It is also used for evaluating nanoparticle-based drug delivery systems, oncolytic viruses, and gene therapies targeting ovarian cancer. Because of its reproducibility, immunocompetent host background, and biological similarity to human disease, ID8 remains the benchmark syngeneic model for immuno-oncology and ovarian carcinoma research.

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To request the ID8 syngeneic model for your preclinical studies, please use the form below. A customized quote and additional model specifications will be provided upon inquiry.

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