Wound Healing Markers – Definition and Significance

What Are Wound Healing Markers?

Wound healing markers are biological parameters – including molecules, proteins, cells, and clinical signs – that provide information about the current status and progression of wound healing. They are used in modern wound care to objectively monitor the healing process, detect complications such as infections or chronic wound states early, and guide therapeutic decisions.

Phases of Wound Healing

Wound healing proceeds through four sequential, partially overlapping phases, each characterized by specific active markers:

• Hemostasis phase: Immediate cessation of bleeding through platelet activation and fibrin formation. Markers: platelets, fibrinogen, thrombin.
• Inflammatory phase: Infiltration of immune cells to combat pathogens. Markers: interleukins (IL-1, IL-6), tumor necrosis factor-alpha (TNF-α), C-reactive protein (CRP), leukocytes.
• Proliferation phase: New tissue and blood vessel formation. Markers: growth factors such as VEGF (Vascular Endothelial Growth Factor), PDGF (Platelet-Derived Growth Factor), EGF (Epidermal Growth Factor), type III collagen.
• Remodeling phase: Restructuring and maturation of scar tissue. Markers: type I collagen, matrix metalloproteinases (MMPs), TIMPs (Tissue Inhibitors of Metalloproteinases).

Key Wound Healing Markers at a Glance

Inflammatory Markers

Inflammatory markers indicate whether a wound is infected or whether the inflammatory response is abnormally prolonged. The most important include:

• CRP (C-reactive protein): Significantly elevated during inflammation and infection; a sensitive marker for wound infections.
• Leukocytes (white blood cells): Elevated levels indicate an active immune response.
• Procalcitonin: A specific marker for bacterial infections, relevant in severe wound infections.
• Interleukins (IL-1β, IL-6, IL-10): Cytokines that regulate the inflammatory process and can be both healing-promoting and healing-inhibiting.

Growth Factors

Growth factors control cell proliferation and tissue regeneration. They are considered central markers and mediators of wound healing:

• VEGF: Promotes the formation of new blood vessels (angiogenesis), essential for supplying wound tissue with nutrients and oxygen.
• PDGF: Stimulates fibroblasts and supports tissue repair.
• EGF: Promotes the proliferation and migration of epithelial cells, facilitating wound closure.
• TGF-β (Transforming Growth Factor-beta): Regulates collagen synthesis and scar formation.

Matrix Metalloproteinases (MMPs)

Matrix metalloproteinases are enzymes that break down and remodel the extracellular matrix. In chronic wounds, MMPs are often persistently elevated, inhibiting the healing process. The balance between MMPs and their inhibitors (TIMPs) is an important diagnostic indicator of wound status.

Collagen Markers

Collagen is the most important structural protein of the skin and connective tissue. The transition from type III collagen (dominant in early healing phases) to type I collagen (dominant in the remodeling phase) is a sign of advancing wound healing.

Clinical Markers

In addition to laboratory parameters, clinical observations also play an important role:

• Wound size and depth (planimetric measurement)
• Amount and characteristics of wound exudate
• Granulation tissue and degree of epithelialization
• Wound odor as an indicator of infection

Significance in Chronic Wounds

In chronic wounds – such as diabetic foot ulcers, pressure ulcers, or venous leg ulcers – the normal healing phases are disrupted. These wounds typically show chronically elevated inflammatory markers, an imbalance of MMPs, and reduced concentrations of growth factors. Assessing wound healing markers in this context enables targeted diagnosis and therapy management.

Diagnostic Methods

Wound healing markers can be determined through various approaches:

• Blood tests: CRP, leukocytes, procalcitonin, cytokines
• Wound exudate analysis: Measurement of MMPs, growth factors, and pH directly in the wound environment
• Tissue biopsy: Histological examination of cellular and molecular markers
• Point-of-care tests: Rapid tests at the bedside, e.g., MMP rapid tests integrated into wound dressings

Therapeutic Relevance

Knowledge of the wound healing marker profile enables individualized therapy. Growth factors can be applied specifically, inflammatory responses can be modulated, and MMP-inhibiting wound dressings can be used. Modern wound dressings increasingly incorporate integrated biosensors for continuous monitoring of wound healing markers.

References

1. Eming, S. A., Martin, P., Tomic-Canic, M. (2014). Wound repair and regeneration: mechanisms, signaling, and translation. Science Translational Medicine, 6(265), 265sr6.
2. Schultz, G. S. et al. (2003). Wound bed preparation: a systematic approach to wound management. Wound Repair and Regeneration, 11(s1), S1-S28.
3. World Health Organization (WHO): Chronic wound care and management guidelines. WHO Technical Reports. Geneva.