# Enhanced proliferation tracer reveals Dorsal-Ventral asymmetry in tracheal epithelial Renewal​

## TL;DR

This study introduces a new lineage tracing method to show that tracheal epithelial renewal is uneven, with dorsal and ventral regions relying on different cell types for regeneration.

## Contribution

The development of evProTracer, an enhanced lineage tracing system, enables precise tracking of epithelial renewal dynamics in vivo.

## Key findings

- Tracheal epithelium undergoes nearly complete homeostatic turnover over 25 weeks.
- Dorsal regions show a basal cell-driven renewal pattern with a bias toward club cell differentiation.
- Ventral renewal is primarily mediated by non-basal progenitors active during homeostasis.

## Abstract

To elucidate spatiotemporal dynamics of tissue renewal, we developed evProTracer, an enhanced dual-recombinase lineage tracing system for cumulative in vivo labeling of proliferating cells. Robust longitudinal tracing using evProTracer in murine tracheal epithelium revealed near-complete homeostatic turnover (91.6 ± 1.29% epithelial replacement over 25 weeks), while basal cell-specific ​Trp63-evProTracer​ uncovered a dorsally biased proliferation pattern​, contributing 33.88 ± 1.44% of total epithelial renewal over 6 months, with early differentiation bias toward club cells. These data demonstrate that ventral epithelial renewal is primarily mediated by non-basal facultative progenitors, revealing their constitutive activation during homeostasis. This study uncovers spatially stratified renewal hierarchies: dorsal basal stem cell reservoirs versus ventral facultative non-basal progenitors. evProTracer provides a versatile platform for investigating tissue plasticity hierarchies in regenerative organs.

The online version contains supplementary material available at 10.1186/s13287-025-04888-0.