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Evaluating the Translation Value of Two In Vivo Models for Breast Cancer Brain Metastases
by
,
Sigrid Cold
1,2,3, 
Maria Zeiler Alfsen
1,
Brandur Halgirsson
1,
Mads Neergaard Jorgensen
1,
Jacob Hald
1,
Carsten Haagen Nielsen
1,
Andreas Kjaer
2,3
,
Lotte Kellemann Kristensen
1 and
Trine Bjornbo Engel
1,* 1
Minerva Imaging ApS, 3650 Oelstykke, Denmark
2
Cluster for Molecular Imaging, Department of Biomedical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
3
Department of Clinical Physiology and Nuclear Medicine, Copenhagen University Hospital, Rigshospitalet, 2100 Copenhagen, Denmark
*
Author to whom correspondence should be addressed.
Cancers 2026, 18(7), 1095; https://doi.org/10.3390/cancers18071095
Submission received: 24 February 2026
/
Revised: 17 March 2026
/
Accepted: 21 March 2026
/
Published: 27 March 2026
(This article belongs to the Section Cancer Metastasis)
Simple Summary
Translational animal models of breast cancer brain metastasis (BCBM) support the development of urgently needed therapies. Today, the most commonly used murine model is generated by stereotactic implantation of breast cancer cells into the mouse brain. While the model is reproducible and reliable, it lacks several important aspects of BCBM, including extravasation of cancer cells from the blood into the brain and micro-seeding. In this study, we established a reproducible BCBM model by injecting breast cancer cells into the carotid artery of mice and evaluated the model in terms of operational success, animal welfare and tumour establishment against the stereotactic model. The intracarotid model was found to mimic BCBM to a greater extent than the stereotactic model, with the establishment of multiple metastasis in the brain. Furthermore, a difference in the blood–brain barrier permeability was observed between the two models, a critical factor for drug delivery to intracranial lesions.
Abstract
Background: Breast cancer brain metastases (BCBM) lack effective treatments, contributing to breast cancer-related morbidity and mortality. Integrating translational animal models and advanced non-invasive imaging can accelerate the development of urgently needed therapies. Method: In this study, we developed an intracarotid method mimicking BCBM and compared it to the stereotactic model in terms of animal welfare, tumour establishment, and blood–brain barrier (BBB) permeability. BCBM was established through intracarotid or stereotactic inoculation of BT474 and MDA-MB-231.Luc2 cells in NMRI nude mice. We utilised magnetic resonance imaging (MRI) and bioluminescence imaging (BLI) to monitor tumour growth and BBB permeability, supported by fluorescent immunohistochemistry for validation. Finally, light sheet microscopy (LSM) was employed to visualise tumour establishment in intact brains. Results: Both inoculation methods achieved a survival rate >70%, with animals recovering within a week post-surgery. MRI and BLI effectively visualised tumour growth with stereotactic implantation, resulting in single tumours, while intracarotid inoculation led to micro-seeding of up to seven tumours in one brain. Tumour growth was rapid and homogenous in the stereotactic model, whereas the intracarotid model exhibited slower, heterogenous growth. Notably, BBB permeability was significantly higher in small tumours in the stereotactic model when compared to the intracarotid model (p = 0.003). Ex vivo analyses validated these findings with the identification of multiple metastasis in the intracarotid model and single tumours in the stereotactic model. Conclusion: We developed an animal model that closely mimics BCBM, highlighting extravasation and micro-seeding while maintaining animal welfare. Our established imaging protocols enable longitudinal evaluations of BBB permeability and treatment response, creating a translational platform for testing novel anti-cancer therapies.
