Fibroblast distribution and localization in male reproductive organs: a mouse model study via lineage tracing

Distribución y localización de fibroblastos en los órganos reproductores masculinos: un estudio en modelo murino mediante trazado de linaje

Background: Fibroblasts are vital for tissue structure, repair, and fibrosis in male reproductive organs, but tools for investigating their localization and distribution are limited. This study employed the collagen type I alpha 2 Cre recombinase estrogen receptor tandem dimer Tomato (Col1a2CreERtdT omato (T om)) lineage tracing mouse model, enabling tamoxifen-inducible, fibroblast-specific labeling through Cre recom-bination under the Col1a2 promoter. This system labels collagen-producing fibroblasts with tdTomato, enabling lineage tracing and visualization of their organization in the penis, prostate, and testis. The study aimed to investigate fibroblast distribution and localization in these organs using this model. Methods: Male Col1a2CreERT om mice (n = 5–6) received tamoxifen (1 mg/day/mouse, intraperitoneal, for 5 consecutive days) to induce Cre recombination and label collagen-producing fibroblasts with tdTomato. Wild type (WT) control mice (n = 3) also received tamoxifen. Two days after the last injection, penis, prostate, and testis tissues were harvested, sectioned, and examined through microscopy on tdTomato epifluorescence. Fibroblasts were quantified as the percentage of tdTomato+ cells relative to total cells. Results: Quantification revealed distinct fibroblast distribution patterns among the organs. In the Col1a2CreERT om mouse, tdTomato+ fibroblasts were most abundant in the penis (75.24 ± 1.6%), followed by the prostate (26.02 ± 1.4%) and testis (13.97 ± 0.9%). Within the penis, the subtunical region had the highest density (93.42 ± 0.5%). In the prostate, fibroblasts were mainly within the fibromuscular stroma; in the testis, they were in the tunica albuginea and interstitial compartments. No tdTomato+ cells were observed in WT controls. Conclusions: The number and location of collagen-producing fibroblasts differ among the penis, prostate, and testis, and vary within penile compartments. These findings reflect the organ- and region-specific distribution of Col1a2-lineage fibroblasts, as revealed by tamoxifen-induced tdTomato lineage tracing. This study provides a useful tool for further investigation of fibroblast function in male reproductive health.

Resumen

Antecedentes: Los fibroblastos son esenciales para la estructura tisular, la reparación y la fibrosis en los órganos reproductivos masculinos, pero existen herramientas limitadas para investigar su localización y distribución. Este estudio empleó el modelo de ratón de trazado de linaje colágeno tipo I alfa 2 Cre recombinasa receptor de estrógeno; tandem dimer Tomato (Col1a2CreERtdT omato (T om)), que permite el marcaje específico de fibroblastos inducible por tamoxifeno mediante recombinación Cre bajo el promotor Col1a2. Este sistema marca fibroblastos productores de colágeno con tdTomato, permitiendo el trazado de linaje y la visualización de su organización en pene, próstata y testículo. El objetivo fue investigar la distribución y localización de fibroblastos en estos órganos utilizando este modelo. Métodos: Ratones machos Col1a2CreERT om (n = 5–6) recibieron tamoxifeno (1 mg/día/ratón, intraperitoneal, durante 5 días consecutivos) para inducir la recombinación Cre y marcar fibroblastos productores de colágeno con tdTomato. Los ratones control de tipo silvestre (WT, n = 3) también recibieron tamoxifeno. Dos días después de la última inyección, se recolectaron pene, próstata y testículo, seccionaron y examinaron mediante microscopía de epifluorescencia para tdTomato. Los fibroblastos se cuantificaron como el porcentaje de células tdTomato+ respecto al total de células. Resultados: La cuantificación reveló patrones distintos de distribución fibroblástica entre órganos. En los ratones Col1a2CreERT om, los fibroblastos tdTomato+ fueron más abundantes en el pene (75.24 ± 1.6%), seguidos por la próstata (26.02 ± 1.4%) y el testículo (13.97 ± 0.9%). En el pene, la región subtunical presentó la mayor densidad (93.42 ± 0.5%). En la próstata, los fibroblastos se localizaron principalmente en el estroma fibromuscular; en el testículo, en la túnica albugínea y los compartimentos intersticiales. No se observaron células tdTomato+ en los controles WT. Conclusiones: El número y la localización de fibroblastos productores de colágeno difieren entre pene, próstata y testículo, y varían dentro de los compartimentos penianos. Estos hallazgos reflejan la distribución órgano- y región-específica de los fibroblastos de linaje Col1a2, revelada mediante trazado de linaje inducido por tamoxifeno con tdTomato. Este estudio proporciona una herramienta útil para futuras investigaciones sobre la función de los fibroblastos en la salud reproductiva masculina.

Collagen-expressing fibroblasts; Penis; Prostate; Testis; Lineage tracing

Palabras Clave

Fibroblastos que expresan colágeno; Pene; Próstata; Testículo; Trazado de linaje

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