Methodological Framework for a Multimodal Rat Model of Bleomycin-Induced Fibrosis and Autologous Tissue Grafting

Reproducible experimental models of localized dermal-hypodermal fibrosis are essential for standardized investigation of regenerative interventions. Variability in bleomycin dosing, anatomical targeting, and assessment strategies limits cross-study comparability. This study describes a methodological framework for standardized induction of early dermal-hypodermal remodeling in a rat model followed by autologous subcutaneous tissue grafting and multimodal longitudinal evaluation. Female Wistar rats underwent subcutaneous bleomycin administration at 1 mg/kg/day for three consecutive days. Clinical documentation, high-frequency ultrasonography with fixed imaging parameters, and sequential biopsies from a predefined thoracic anatomical site were performed at baseline, intermediate reassessment, and final evaluation. Autologous subcutaneous tissue grafting was conducted at Day 17 after study initiation. The protocol enabled controlled induction of early structural remodeling and consistent longitudinal documentation of dermal-hypodermal thickness, echogenicity changes, and histological architecture within a standardized anatomical region. This protocol development study establishes a reproducible and spatially consistent experimental platform integrating imaging and histological assessment, facilitating future hypothesis-driven investigations of fibrotic remodeling and regenerative strategies.