What Is Wound Healing?
Wound healing is the biological process by which the organism repairs injured tissues, restoring the structural and functional integrity of the skin and underlying tissues. It is a complex and highly coordinated physiologic cascade involving immune cells, fibroblasts, endothelial cells, and growth factors.
When this process proceeds normally, the wound moves in an orderly manner through well-defined phases until a mature scar forms. Several factors, however, can disrupt this progression, resulting in chronic non-healing wounds or pathologic scars such as keloids and hypertrophic scars.
Understanding healing physiology is essential for identifying the points where therapeutic interventions — including medical acupuncture — can optimize tissue repair. Preclinical and clinical studies suggest that acupuncture can act on fibroblasts, microcirculation, and inflammatory mediators, with potential to favor the healing process and the quality of the scar.
Multiphasic Process
Healing involves four overlapping phases: hemostasis, inflammation, proliferation, and remodeling — each with critical functions.
Risk Factors
Diabetes, poor circulation, malnutrition, infection, and use of certain medications can significantly delay healing.
Action of Acupuncture
Experimental studies (Langevin and colleagues) suggest that acupuncture may activate fibroblasts and modulate microcirculation and the inflammatory response; extrapolation to clinical improvement of healing requires confirmation.
Pathophysiology: The Phases of Healing
Wound healing is classically divided into four phases that overlap in time. A detailed understanding of each phase helps identify where the process can fail and where therapeutic interventions can be most effective.
1. Hemostasis (0-24 hours)
The hemostasis phase begins immediately after injury. Damaged blood vessels undergo reflex vasoconstriction, reducing blood flow to the injured area. Platelets adhere to exposed collagen and aggregate, forming a platelet plug stabilized by the coagulation cascade.
The resulting fibrin clot not only stops bleeding but also serves as a provisional matrix on which repair cells will migrate in subsequent phases. Platelets release growth factors such as PDGF (platelet-derived growth factor) and TGF-beta, which signal to inflammatory cells and fibroblasts.
2. Inflammation (1-7 days)
Neutrophils are the first leukocytes to arrive at the wound, performing initial cleanup of bacteria and cellular debris. After 48-72 hours, macrophages become the dominant cells and play a central role: they phagocytose pathogens, remove necrotic tissue, and release cytokines that orchestrate the subsequent phases.
Macrophages are the "conductors" of healing. They shift from a pro-inflammatory phenotype (M1) to an anti-inflammatory one (M2), signaling the move from the inflammatory to the proliferative phase. When this shift fails — as occurs in diabetic wounds — inflammation becomes chronic and healing stalls.
3. Proliferation (4-21 days)
In the proliferative phase, three processes occur simultaneously: granulation tissue formation, angiogenesis, and reepithelialization. Fibroblasts migrate to the wound and synthesize type III collagen, hyaluronic acid, and other components of the new extracellular matrix.
Angiogenesis — the formation of new blood vessels — is driven by VEGF (vascular endothelial growth factor) and ensures oxygen and nutrients reach the forming tissue. At the same time, keratinocytes at the wound edges proliferate and migrate across the new matrix, restoring the epidermal barrier.
Myofibroblasts — differentiated fibroblasts with contractile capacity — drive wound contraction, gradually shrinking the area that must be filled with new tissue.
4. Remodeling (21 days to 2 years)
The longest phase of healing, remodeling involves the gradual replacement of type III collagen with type I collagen, more resistant and organized. Collagen fibers align along the lines of tension, increasing the mechanical resistance of the scar.
By the end of remodeling, the mature scar reaches at most 80% of the tensile strength of the original skin — it never fully recovers. Myofibroblasts undergo apoptosis, and excess vascularization regresses. Imbalances in this phase produce hypertrophic scars (excess collagen within the wound's limits) or keloids (extending beyond the original margins).
Phases of Wound Healing
Phase 1
0-24 hoursHemostasis
Vasoconstriction, platelet aggregation, fibrin clot formation, and release of growth factors.
Phase 2
1-7 daysInflammation
Neutrophils and macrophages clean the wound. Transition of macrophages from M1 (pro-inflammatory) to M2 (anti-inflammatory).
Phase 3
4-21 daysProliferation
Granulation tissue formation, angiogenesis, fibroblast collagen synthesis, and reepithelialization.
Phase 4
21 days to 2 yearsRemodeling
Replacement of type III collagen with type I, fiber alignment, scar maturation (maximum 80% of original strength).
Types of Wounds and Clinical Signs
Wound classification is essential for guiding therapeutic management. Acute wounds follow the expected physiologic progression, while chronic wounds remain stuck in one or more phases of healing.
CLASSIFICATION OF WOUND TYPES
| WOUND TYPE | FEATURES | EXPECTED COURSE |
|---|---|---|
| Surgical wound | Regular edges, clean, primary closure | Healing by first intention (7-14 days) |
| Traumatic wound | Irregular edges, possible contamination | Variable according to extent and depth |
| Burn | Thermal, chemical, or electrical injury with varying degrees | Depends on degree (superficial to deep) |
| Diabetic ulcer | Neuropathic or ischemic, in the lower extremities | Chronic — requires prolonged treatment |
| Venous ulcer | Medial malleolar region, lipodermatosclerosis | Chronic — compression is essential |
| Pressure ulcer | Bony prominences, bedridden patients | Chronic — pressure relief and nutrition |
Signs of Compromised Healing
- 01
Absence of progress after 2-4 weeks
A wound that does not shrink or that shows pale granulation tissue suggests the proliferative phase has stalled.
- 02
Excessive or purulent exudate
Heavy drainage — especially if turbid, greenish, or foul-smelling — points to possible infection.
- 03
Wound edges "rolled" or erythematous
Epibole (edges that curl in on themselves) blocks keratinocyte migration.
- 04
Necrotic (eschar) or devitalized tissue
Yellowish (slough) or darkened (eschar) tissue blocks healing and invites infection.
- 05
Disproportionate or increasing pain
Worsening pain may signal deep infection, ischemia, or compression of adjacent structures.
- 06
Persistent unpleasant odor
A foul odor that persists after thorough cleaning suggests significant bacterial colonization or necrosis.
Wound Healing Assessment
A systematic wound evaluation guides etiologic diagnosis and therapeutic planning. Validated instruments such as the PUSH scale (Pressure Ulcer Scale for Healing) and the Vancouver scale for scars allow progress to be documented objectively.
🏥Clinical Wound Assessment
Fonte: Wound Healing Society Guidelines
Assessment Parameters
- 1.Dimensions: length, width, and depth (serial measurement)
- 2.Wound bed: granulation tissue (red), slough (yellow), necrosis (black)
- 3.Edges: adherent, undermined, epibole, maceration
- 4.Periwound skin: erythema, edema, maceration, warmth, fluctuation
- 5.Exudate: volume, color, consistency, and odor
Complementary Tests
- 1.Glucose and glycated hemoglobin (rule out uncontrolled diabetes)
- 2.Serum albumin and prealbumin (assess nutritional status)
- 3.Complete blood count (leukocytosis, anemia)
- 4.Tissue culture with antibiogram (if infection is suspected)
- 5.Arterial and venous Doppler (to assess lower-limb perfusion)
Factors That Compromise Healing
Several systemic and local factors can delay or prevent adequate healing. Identifying and correcting them is the first step in managing chronic wounds.
FACTORS THAT COMPROMISE HEALING
| FACTOR | MECHANISM OF IMPAIRMENT | MANAGEMENT |
|---|---|---|
| Diabetes mellitus | Hyperglycemia impairs neutrophil and macrophage function, reduces angiogenesis and collagen synthesis | Strict glycemic control (HbA1c < 7%) |
| Local infection | Bacterial biofilm sustains chronic inflammation and degrades growth factors and the extracellular matrix | Debridement, cultures, targeted antibiotic therapy |
| Vascular insufficiency | Ischemia limits the supply of oxygen, nutrients, and repair cells | Vascular evaluation, revascularization if indicated |
| Malnutrition | Protein, vitamin C, zinc, and iron deficiencies compromise collagen synthesis and immunity | Protein and micronutrient supplementation |
| Corticosteroids | Inhibit inflammation, macrophage migration, fibroblast proliferation, and angiogenesis | Reduce dose when possible, topical vitamin A |
| Smoking | Nicotine causes vasoconstriction, carbon monoxide reduces tissue oxygenation | Smoking cessation — improves circulation within 48h |
| Advanced age | Reduced cell proliferation, blunted inflammatory response, and more fragile collagen | Optimize nutrition, hydration, and mobility |
Conventional Treatment
Wound treatment rests on a few core principles: controlling systemic factors, preparing the wound bed, choosing an appropriate dressing, and regular follow-up. The TIME approach (Tissue, Infection/Inflammation, Moisture, Edge) is widely used as a management framework.
Wound Bed Preparation
Debridement removes necrotic tissue and bacterial biofilm, allowing viable tissue to be exposed and healing to progress. Options include surgical debridement (scalpel), autolytic (occlusive dressings), enzymatic (collagenase), and mechanical.
A controlled moist environment is essential for healing — studies show that wounds kept moist heal up to 50% faster than wounds exposed to air. Excess moisture, however, macerates the periwound skin. Dressing selection should balance absorption and hydration based on the characteristics of the exudate.
DRESSINGS AND INDICATIONS
| DRESSING | INDICATION | MECHANISM |
|---|---|---|
| Hydrogel | Dry wound, necrosis | Hydration of the bed, autolytic debridement |
| Calcium alginate | Highly exudative wound | High absorption, hemostasis, calcium ion exchange |
| Polyurethane foam | Moderate to abundant exudate | Absorbs exudate while keeping the wound moist, plus mechanical protection |
| Hydrocolloid | Wound with little exudate | Occlusive moist environment, autolytic debridement |
| Nanocrystalline silver | Infection or high risk of infection | Broad-spectrum antimicrobial action |
| Negative pressure wound therapy | Complex wounds, post-surgical | Removes exudate, stimulates granulation, reduces edema |
Advanced Therapies
For chronic wounds that do not respond to conventional treatment, advanced therapies can be considered. Hyperbaric oxygen therapy increases the partial pressure of oxygen in tissues, stimulating angiogenesis and leukocyte function. Recombinant growth factors (such as becaplermin) and biological dermal substitutes are options in selected cases.
In this context, medical acupuncture emerges as a complementary therapy under investigation — its proposed mechanisms on healing are still being validated — and can be integrated into the multidisciplinary therapeutic plan coordinated by the physician.
Acupuncture as Treatment
Medical acupuncture has proposed mechanisms — supported mostly by preclinical studies — that are potentially relevant to healing. Clinical trials in open wounds remain limited, and most clinical evidence is restricted to scar management (hypertrophic/keloid) rather than to the healing of open wounds.
Three main mechanisms support the use of acupuncture in healing: fibroblast activation, improvement of microcirculation, and modulation of the inflammatory response. Each of these mechanisms acts on distinct phases of the repair process, making acupuncture an intervention that can benefit patients at different stages.
Fibroblast Activation and Mechanical Signaling
The pioneering work of Langevin et al. showed that rotating the acupuncture needle generates a mechanical deformation in connective tissue that propagates several centimeters around the insertion point. This mechanotransduction activates fibroblasts resident in the tissue, which respond by altering their morphology (cell spreading), increasing collagen synthesis, and releasing growth factors.
A review published in 2026 by Tu et al. in Frontiers in Immunology confirmed that fibroblasts are key effectors of acupuncture. Mechanical needle stimulation activates intracellular pathways such as Rho/ROCK and mechanosensitive ion channels, resulting in increased extracellular ATP production, extracellular matrix remodeling, and cytokine modulation. These effects are particularly relevant for wounds stagnated in the inflammatory phase.
Improvement of Microcirculation
Acupuncture consistently improves local and regional microcirculation. Studies with laser Doppler and flowmetry show a significant increase in cutaneous blood flow after needle insertion, mediated by the release of calcitonin gene-related peptide (CGRP) and nitric oxide (NO) by sensory nerve terminals.
This improvement in blood flow is particularly relevant in wounds with an ischemic component — such as diabetic ulcers and wounds in poorly perfused areas. Better tissue oxygenation supports neutrophil function (which depends on oxygen to produce reactive antimicrobial species), fibroblast proliferation, and angiogenesis.
Anti-inflammatory Modulation
In chronic wounds, persistent inflammation is the main obstacle to healing. Preclinical studies and investigations in humans suggest that acupuncture can modulate the inflammatory response through multiple pathways — described in the literature as activation of the cholinergic anti-inflammatory reflex via the vagus nerve, reduction of pro-inflammatory cytokines (TNF-alpha, IL-1beta, IL-6), and promotion of the macrophage shift from the M1 (pro-inflammatory) to M2 (pro-reparative) phenotype.
This modulation allows wounds "stuck" in the inflammatory phase to progress to the proliferative phase. Low-frequency electroacupuncture (2-4 Hz) shows a more robust anti-inflammatory effect and is preferred for managing chronic inflamed wounds.
Acupuncture for Scars
Recent systematic reviews by Trybulski et al. (2024) and Chmielewska et al. (2024) evaluated dry needling and acupuncture for scar treatment. The results indicate improvement in elasticity, reduction in thickness, and decrease in pain and pruritus in hypertrophic scars and keloids. The mechanism involves collagen remodeling, breakdown of fascial adhesions, and normalization of scar vascularization.
The intrascar needling technique — inserting needles directly into the scar — shows promising results in reducing excessive fibrosis. Mechanical stimulation reorganizes misaligned collagen fibers and activates matrix metalloproteinases (MMPs), driving controlled remodeling of the scar tissue.
Prognosis
Healing prognosis depends fundamentally on the type of wound, the presence of confounding factors, and the adequacy of treatment. Acute wounds in healthy patients have an excellent prognosis, while chronic wounds require a prolonged, multidisciplinary approach.
The healing rate can be estimated from the percentage of wound area reduction at 4 weeks: a 40-50% reduction in this period predicts a good outcome. Wounds that do not reach this threshold likely require diagnostic and therapeutic reassessment.
Healing Expectations by Wound Type
Acute
1-2 weeksClean Surgical Wound
Healing by first intention in 7-14 days. Sutures removed in 7-10 days, depending on location.
Acute
2-3 weeksSuperficial Second-Degree Burn
Reepithelialization in 10-21 days from preserved dermal appendages. Low risk of pathologic scar.
Chronic
3-6 monthsVenous Ulcer
With adequate compression therapy, healing in 3-6 months. Recurrence in 30-70% of cases without prevention.
Chronic
3-12 monthsDiabetic Ulcer
Healing in 3-12 months with glycemic control and adequate offloading. Amputation risk rises when critical ischemia is present.
Myths and Facts
Myth vs. Fact
Letting the wound "breathe" in the open air accelerates healing.
Wounds kept in a controlled moist environment heal up to 50% faster. Air exposure dries the wound bed and slows cell migration.
Hydrogen peroxide and alcohol are the best products to clean wounds.
Hydrogen peroxide and alcohol are cytotoxic to fibroblasts and keratinocytes. Cleaning with normal saline is safer and more effective.
Chronic wounds are impossible to heal.
Most chronic wounds can heal once the underlying obstacles are corrected: glycemic control, nutrition, perfusion, and infection management.
Acupuncture in wounds can cause infection.
Medical acupuncture uses sterile, disposable needles. Periwound needling (around the wound, not over it) is generally safe — though infected wounds or compromised skin call for extra caution, and the decision to needle the area around a wound requires case-by-case evaluation by the physician.
When to Seek Medical Help
Frequently Asked Questions about Wound Healing
Healing occurs in four overlapping phases: hemostasis (0-24 hours, clot formation), inflammation (1-7 days, cleanup by neutrophils and macrophages), proliferation (4-21 days, granulation tissue formation, angiogenesis, and reepithelialization), and remodeling (21 days to 2 years, collagen and scar maturation). Each phase is essential, and interrupting any one of them compromises healing.
Chronic hyperglycemia compromises virtually every phase of healing. It weakens neutrophils' ability to fight infection, prevents macrophages from switching from the pro-inflammatory to the reparative phenotype, slows fibroblast proliferation and collagen synthesis, and impairs new blood vessel formation. Diabetic neuropathy also dulls pain perception, allowing injuries to go unnoticed until they become serious. Strict glycemic control is essential for any treatment to be effective.
Acupuncture works through three main mechanisms: it activates fibroblasts via mechanotransduction (the mechanical deformation caused by the needle stimulates collagen synthesis and growth factor release), improves local microcirculation (boosting oxygen and nutrient supply through CGRP and nitric oxide release), and modulates the inflammatory response (reducing pro-inflammatory cytokines and shifting macrophages from M1 to M2). These effects are especially relevant in stalled chronic wounds.
Needling is not done directly over an open wound. The technique used is periwound needling — sterile needles inserted around the wound, into intact tissue — which stimulates microcirculation and cellular activity at the lesion's edge. For closed scars (hypertrophic or keloid), direct intrascar needling can be indicated to remodel the fibrotic tissue. Both techniques are safe when performed by a medical acupuncturist.
The number of sessions depends on the type and severity of the wound. For acute wounds healing normally, 4-6 sessions can be enough to optimize repair. For chronic wounds, the recommendation is to start with biweekly sessions for 3-4 weeks and reassess progress. The medical acupuncturist tracks objective indicators such as wound area reduction and granulation tissue quality to adjust the protocol.
Yes — recent systematic reviews show that intrascar needling improves elasticity, reduces thickness, and eases symptoms such as pain and itching in hypertrophic scars and keloids. The mechanism involves reorganizing misaligned collagen fibers, activating matrix metalloproteinases that drive controlled remodeling, and normalizing vascularization. Results are most striking when treatment begins in the first months after scar maturation.
The main factors are: uncontrolled diabetes (compromises every phase of healing), local infection with biofilm formation, arterial or venous insufficiency, malnutrition (especially protein, vitamin C, and zinc deficiency), chronic corticosteroid use, smoking (causes vasoconstriction and reduces tissue oxygenation), and advanced age. Correcting these factors is the first and most important step in managing any chronic wound.
A controlled moist environment is essential because it helps keratinocytes and fibroblasts migrate across the wound bed (cells don't move well on dry surfaces), prevents crusts that act as a mechanical barrier to reepithelialization, preserves the activity of growth factors and enzymes in the exudate, and reduces pain by protecting exposed nerve endings. Studies show that wounds in a moist environment heal up to 50% faster than wounds exposed to air.
Local signs of infection include: increased pain, redness that spreads beyond the wound edges, local warmth, progressive swelling, and changes in the exudate (which becomes turbid, greenish, or foul-smelling). Systemic signs include fever, chills, and malaise. A wound that was improving and suddenly worsens is highly suspicious. Seek medical evaluation so a culture can be collected and targeted antibiotic therapy started if needed.
Yes — acupuncture works best as part of an integrated protocol coordinated by the physician. It can be combined with advanced dressings, compression therapy (in venous ulcers), glycemic control, nutritional supplementation, and hyperbaric oxygen therapy. Acupuncture does not replace proper local wound care but enhances the body's response to conventional treatment, especially in refractory cases.
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