Collagen composition in equine exuberant granulation tissue reflects tissue immaturity.
Authors: Partusch Lena, Rutland Catrin Sian, Martens Ann, Du Cheyne Charis, De Spiegelaere Ward, Michler Jule Kristin
Journal: PloS one
Summary
Exuberant granulation tissue (EGT) remains a significant clinical challenge in equine wound management, particularly in distal limb injuries, yet the underlying mechanisms driving its excessive fibroproliferation have not been well characterised. Partusch and colleagues examined collagen composition in naturally occurring EGT from 19 horses compared to six control wounds using histological analysis and immunofluorescence to assess collagen types, myofibroblast distribution, and vascular architecture. The researchers found that EGT contained substantially elevated proportions of immature type III collagen in both superficial and deep wound layers relative to controls, despite total collagen volumes remaining similar between groups; additionally, EGT samples demonstrated occluded microvessels with endothelial hypertrophy, widespread myofibroblast infiltration, and reduced intermediate filament markers in superficial regions. These findings indicate that EGT represents a tissue maturation disorder rather than a simple overproduction problem, with the persistent dominance of immature collagen suggesting the wound remains "stuck" in an early proliferative phase. For practitioners, this mechanistic insight points toward therapeutic strategies aimed at promoting extracellular matrix maturation—potentially through targeted modulation of myofibroblast function or vascular remodelling—rather than simply attempting to reduce overall tissue volume, offering a new direction for improving outcomes in this costly and frustrating condition.
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Practical Takeaways
- •EGT development involves abnormal wound maturation with excessive immature collagen accumulation—future treatments should target collagen remodelling and tissue maturation rather than just removing granulation tissue
- •The persistent presence of myofibroblasts and poor vascular organisation in EGT explains why these wounds remain problematic; therapeutic strategies should address both cellular and vascular dysfunction
- •Understanding that EGT represents tissue immaturity rather than simply excessive growth opens new treatment possibilities that could reduce treatment duration and cost for distal limb wounds
Key Findings
- •EGT wounds contain significantly higher amounts of immature collagen (type III) in both superficial and deep regions compared to control wounds, despite similar total collagen amounts
- •Myofibroblasts are ubiquitously distributed throughout EGT wound beds, with occluded microvessels and endothelial cell hypertrophy present in deep layers
- •Markers for intermediate filaments are reduced in the superficial region of EGT, indicating abnormal cellular organization
- •Collagen composition patterns in EGT reflect tissue immaturity, suggesting that promoting ECM maturation could be a therapeutic target