New Mouse Model Enables Precise Endothelial Cell Ablation

Researchers have developed a novel genetic tool that allows for the highly specific tracing and ablation of endothelial cells in mice. The study, published in Cell Regeneration, introduces the Cdh5-RL-DTRGFP mouse model, which utilizes a dual-recombinase system to overcome the limitations of conventional single-recombinase approaches. By requiring both Dre and Cre recombinases to activate transgene expression, the new model ensures tight control over genetic manipulation in vascular tissues. This advancement provides a robust platform for dissecting the function of endothelial cells in both physiological and pathological contexts.

Endothelial cells line the interior surface of blood vessels and play critical roles in maintaining vascular integrity and regulating disease processes. These cells exhibit significant functional and phenotypic specialization depending on the host tissue. To study their specific contributions, scientists often need to genetically target and remove these cells in vivo. Previous methods, such as the Cre-dependent iDTR system, have been widely used but are constrained by off-target effects and variable efficiency. The new Cdh5-RL-DTRGFP model addresses these issues by employing a logic gate that requires two distinct recombinases for activation.

The core of this new tool is a mouse line engineered to co-express green fluorescent protein (GFP) and the diphtheria toxin receptor (DTR). The DTR confers sensitivity to diphtheria toxin (DT), which, when administered, leads to cell death. In the Cdh5-RL-DTRGFP model, the DTR-GFP fusion protein is placed under the control of the Cdh5 promoter, which is active in endothelial cells. However, expression is silenced by dual transcriptional stop cassettes. One cassette is flanked by rox sites, and the other by loxP sites. Only when both Dre and Cre recombinases are present are these stop cassettes excised, allowing for the expression of DTR and GFP.

To validate the specificity of the model, the researchers first examined the Cdh5-RL-DTRGFP mice in the absence of recombinases. They performed whole-mount fluorescence screening and histological validation using immunofluorescence staining. The results showed no detectable GFP emission across multiple organs, indicating the absence of significant leaky expression. Quantitative analysis confirmed that GFP remained entirely undetectable in VE-cadherin-positive endothelial cells. This complete absence of expression validates the robust functional efficacy of the dual stop cassettes in preventing transcriptional leakage without the required recombinases.

To demonstrate the functionality of the system, the researchers generated a recombinant line by crossing the Cdh5-RL-DTRGFP mice with ACTB-Cre and CAG-Dre drivers. These drivers express Cre and Dre recombinases in all cells, leading to pan-tissue excision of the stop cassettes. In the resulting Cdh5-DTRGFP mice, the dual recombination drove high-level expression of DTR and GFP specifically in endothelial cells. Immunofluorescence staining of tissue sections from these mice demonstrated strong co-localization of GFP and VE-cadherin, confirming endothelial-specific expression. Quantitative evaluation across multiple organs, including the brain, heart, lung, liver, and kidney, revealed that GFP labeling efficiency exceeded 95% in endothelial compartments.

The study further investigated the utility of the model for targeting specific endothelial subpopulations. The researchers incorporated Npr3 as a selective genetic marker to enhance the resolution of endothelial subpopulations. By crossing Npr3-CreER mice with CAG-Dre; Cdh5-L-DTRGFP animals, they generated triple-positive embryos. Tamoxifen induction was performed at embryonic days 13.5 and 14.5, followed by tissue collection 72 hours later. Histological analysis of embryonic heart sections showed specific GFP localization within the endothelial layer. All GFP-positive cells co-expressed VE-cadherin, validating the targeted labeling of the Npr3-positive endothelial cell subset. This demonstrates the model’s capacity for precise spatiotemporal control over specific vascular populations.

To test the ablation capability, the researchers administered a single dose of diphtheria toxin to adult Cdh5-DTRGFP mice. The DT was injected intraperitoneally at a dose of 10 ng/g. This treatment induced severe morbidity, with all treated mice succumbing within two days. In contrast, mice treated with phosphate-buffered saline (PBS) as a control remained healthy. Necropsy revealed striking abnormalities in the liver of the DT-treated mice, which appeared intensely red compared to the controls. The GFP signal was nearly absent in the treated livers, indicating the loss of the targeted cells.

Immunofluorescence staining for GFP, VE-cadherin, and Ter119, an erythrocyte marker, provided further evidence of efficient ablation. The staining showed a near-complete loss of GFP and a substantial reduction in VE-cadherin in the liver, heart, and lungs of DT-treated mice. This was accompanied by a significant accumulation of Ter119-positive erythrocytes in these organs, indicating severe vascular leakage. Higher magnification imaging confirmed the presence of erythrocytes outside the vascular lumen. These phenotypes were absent in DT-administered wild-type mice, confirming that the effects were specific to the DTR-expressing endothelial cells.

The mechanism of cell death involves the binding of diphtheria toxin to the DTR on the cell surface, followed by internalization via endocytosis. This process irreversibly inhibits protein synthesis, leading to cell death. The loss of endothelial cells disrupts the integrity of the vascular wall, leading to vessel rupture and the extravasation of blood cells. The study demonstrates that the Cdh5-RL-DTRGFP system enables specific endothelial ablation, resulting in a rapid and fatal breakdown of vascular integrity. This provides a direct link between endothelial cell loss and the observed physiological consequences.

The dual-recombinase approach offers significant advantages over existing methods. The widely used Rosa26-iDTR model suffers from variable recombination efficiency across different alleles, which can lead to incomplete or unpredictable ablation. By synchronizing the expression of GFP and DTR, the new model ensures that GFP acts as a faithful surrogate marker for DT-sensitive cells. This synchronization addresses the issue of off-target effects and inconsistent efficiency associated with single-recombinase systems. The model thus provides a more reliable tool for genetic dissection of endothelial function.

The versatility of the Cdh5-RL-DTRGFP line extends beyond the constitutive models used in this study. The researchers have also generated Cdh5-L-DTRGFP and Cdh5-R-DTRGFP alleles, which are designed for compatibility with inducible Cre and Dre lines, respectively. This strategic development paves the way for sophisticated future studies, enabling temporal control over the ablation of spatially defined endothelial subpopulations. The tool could be used to investigate the role of specific vascular beds in organogenesis, tumor angiogenesis, or tissue regeneration.

The study highlights the importance of precise genetic tools in understanding the functional heterogeneity of endothelial cells. By allowing researchers to ablate cells with high spatiotemporal precision, the Cdh5-RL-DTRGFP system opens a broader pathway for dissecting the critical roles of endothelial cells in health and disease. The findings establish the model as a robust and definitive platform for vascular, developmental, and disease biology research. This work provides a significant advancement in the toolkit available for studying vascular biology in vivo.

Subject of Research: Dual recombinase-mediated endothelial cell-specific lineage tracing and ablation

Article Title: Dual recombinase-mediated endothelial cell-specific lineage tracing and ablation

Article References: Li, J., Zhang, M., Liu, X., Zhang, Z., Shi, M., Pu, W., & Zhou, B. (2026). Dual recombinase-mediated endothelial cell-specific lineage tracing and ablation. Cell Regeneration, 15(1), Article 7. https://doi.org/10.1186/s13619-026-00280-2

Image Credits: AI Generated

DOI: 10.1186/s13619-026-00280-2

Keywords: Dual, recombinase-mediated, endothelial, cell-specific, lineage, tracing, ablation, scientific research