European Journal of Cardiovascular Medicine

Wound healing is a complex tissue restoration process, proceeding through phases of hemostasis, inflammation, proliferation, and remodeling^1-3

1. Hemostasis (seconds to minutes): Immediately after injury, platelets aggregate to form a clot that stops bleeding and provides a scaffold for healing, while releasing growth factors to initiate repair. Hemostasis is marked by rapid platelet aggregation and clot formation that not only prevents blood loss but starts the healing cascade⁴⁻⁵
2. Inflammation (first 3–5 days): Immune cells such as neutrophils and macrophages migrate to the wound to clear debris and pathogens. Macrophages also secrete cytokines and growth factors like VEGF and TGF-β to promote tissue repair.^6-7
3. Proliferation (days 3 to weeks): New tissue forms through angiogenesis (new blood vessels), fibroblast proliferation and collagen production (fibroplasia), re-epithelialization, are essential for rebuilding tissue integrity^{¹˒⁸⁻¹⁰} which together rebuild the extracellular matrix and skin barrier.
4. Maturation/Remodeling (weeks to months or years): Involves the reorganization of collagen and strengthening the wound, though full tissue strength is rarely restored in adults¹¹⁻¹².

 Key mediators including cytokines and growth factors tightly regulate these phases, while the extracellular matrix provides the structural scaffold necessary for cell migration and regeneration.

Wound type significantly influences healing mode and duration. Surgical incisions usually heal rapidly by primary intention with minimal scarring. Traumatic wounds heal by secondary intention, often taking longer with more scarring. Chronic wounds like diabetic or pressure ulcers often face healing delays due to underlying health issues.

Effective wound management depends on proper dressing selection. Ideal dressings should be easy to apply, economical, protective, maintain moisture, minimize pain, and promote healing without provoking immune reactions.

Biological dressings, especially collagen-based ones, best meet these criteria. Collagen plays a crucial role in wound repair by promoting extracellular matrix reconstruction and reducing inflammation. Collagen granule dressings improve healing outcomes by enhancing collagen deposition, reducing inflammation, and offering biocompatibility and ease of use, making them superior to conventional dressings.

Normal Versus Chronic Wound Healing:

The microenvironment of a normal wound bed (left) is characterized by the presence of various growth factors, a well-organized extracellular matrix (ECM), and responsive cell populations. In a healthy wound, matrix synthesis occurs at a greater rate than its degradation, with matrix metalloproteinase (MMP) activity carefully regulated by MMP inhibitors (TIMPs). Angiogenesis and neovascularization in normal wounds progress in a timely and organized manner, with blood vessel sprouting and the recruitment of endothelial progenitor .the healing process.

In contrast, chronic wounds (right) often exhibit a high incidence of bacterial biofilms, which contribute to persistent inflammation, excessive proteolysis, and the degradation of critical growth factors, receptors, and ECM. The cells within chronic wounds struggle to proliferate and migrate effectively, potentially due to the lack of functional receptors or appropriate matrix substrates that support cell movement. Impaired angiogenesis and neovascularization, key features of chronic wounds, result in insufficient oxygen and nutrient supply, which further exacerbates wound bed damage and impairs the healing process.

In chronic wounds, inflammation, MMP production, matrix degradation, and cell senescence/apoptosis are all elevated. These processes cannot be resolved due to insufficient cell proliferation, inadequate ECM synthesis, reduced production of TIMPs, and impaired angiogenesis/neovascularization. This imbalance ultimately prevents chronic wounds from healing.

CELLULAR PHENOTYPIC ABNORMALITIES IN CHRONIC WOUNDS

 Low Density Growth Factor Receptors and Reduced Mitogenic Potential
The phenotypic abnormalities observed in epidermis- and dermis-derived cells in chronic wounds include a lower density of growth factor receptors and diminished mitogenic potential, which hinder their ability to respond effectively to environmental signals. For example, fibroblasts isolated from patients with chronic diabetic wounds, non-diabetic chronic wounds, or venous insufficiency show a reduced mitogenic response to various growth factors such as PDGF-AB, IGF, bFGF, and epidermal growth factor, whether applied alone or in combination. This reduction is likely due to a decrease in receptor density. Furthermore, fibroblasts from leptin receptor-deficient diabetic mice and patients with chronic venous insufficiency display reduced motility compared to normal fibroblasts. These cellular abnormalities impede the formation of granulation tissue and ECM deposition, resulting in nonhealing wounds.

Impaired Keratinocytes
Keratinocytes derived from chronic ulcers exhibit a "chronic wound-associated" phenotype. While these cells overexpress the proliferation marker Ki67 and show upregulation of genes related to the cell cycle, such as CDC2 and cyclin B1, indicating a hyperproliferative state, they display impaired migratory potential. The mechanisms behind this impairment are not fully understood, but have been linked to decreased production of laminin 332 (previously known as laminin 5), which is essential for keratinocyte migration during wound healing. Additionally, these keratinocytes show increased activation of the A-catenin/c-myc pathway and lack expression of differentiation markers, such as keratin 10 and keratin 2.

Growth Factor Dysregulation
In chronic wounds, several genes encoding growth factors are either up- or down-regulated. For example, the expression of VEGF, epiregulin, and TGF-A2 is decreased, while PDGF and platelet-derived endothelial growth factor genes are up-regulated. The reduced production of certain growth factors confirms the impaired state of keratinocytes in chronic wounds and their inability to fully engage in the repair process. Conversely, the up-regulation of certain growth factors promotes sustained proliferative capacity, suggesting that targeting these factors could be a potential therapeutic intervention.

Mitogenic stimuli, combined with activators of keratinocyte differentiation (such as hyperforin), may induce phenotypic changes in chronic wound keratinocytes, transforming them into competent cells necessary for epithelialization. Additionally, modern gene transduction techniques could be used to enhance the responsiveness of cells in chronic wounds by increasing the density of growth factor receptors, thus improving their healing potential.

FACTORS IN THE EXTRA CELLULAR MATRIX MICROENVIRONMENT THAT CONTRIBUTE TO THE PERSISTENCE OF WOUND CHRONICITY

The chronic wound bed microenvironment is marked by changes in the matrix composition. Unlike acute wounds, the deposition of several matrix components in chronic wounds is altered:

• Chronic wounds exhibit prolonged or insufficient expression of fibronectin, chondroitin sulfate, and tenascin, leading to impaired cellular proliferation and migration.
• A reduced production of laminin 332, a key basement membrane component that acts as a chemotactic substrate for keratinocyte motility after injury, has been identified as a contributing factor to impaired reepithelialization and poor wound healing.
• Modifications to the ECM, including post-translational alterations to essential structural components, can negatively impact cellular responses to injury.
• Matrix glycation, commonly observed in diabetic patients, is linked to premature cell senescence, apoptosis, and inhibition of cell proliferation, migration, and angiogenesis, further impeding wound healing.
• Glycation also contributes to matrix instability and disrupts the interaction between collagen and its binding partners, such as heparan sulfate proteoglycans.
• Elevated glucose levels have been shown to stimulate MMP production in fibroblasts, macrophages, and endothelial cells, creating a "vicious cycle" of matrix degradation that negatively impacts cell survival and inhibits wound healing.
• The instability of the matrix due to glycation, insufficient intermolecular cross-linking under hypoxic conditions, and excessive MMP-mediated degradation further complicates the healing process.
• Matrix instability prevents normal cell-matrix interactions necessary for cell survival and function and, ultimately, injury repair. Therefore, inhibition of matrix degradation, addition of exogenous matrices, and induction of matrix synthesis by resident cells all provide therapeutic opportunities.
• Matrix instability impedes normal cell-matrix interactions, which are essential for cell survival, function, and ultimately, injury repair. Therefore, strategies to inhibit matrix degradation, introduce exogenous matrices, and stimulate matrix synthesis by resident cells represent promising therapeutic approaches.

BIOFILMS :-

Infection is an extrinsic factor that significantly delays wound healing, contributing to chronicity, increased morbidity, and mortality. Bacterial counts exceeding 105 viable bacteria or the presence of A-haemolytic streptococci are considered harmful to the healing process. Bacterial toxins, along with live bacteria, induce excessive inflammation and tissue damage, leading to complications such as abscess formation, cellulitis, osteomyelitis, or even limb loss in diabetic patients.

Additionally, inflammatory cells and bacteria within the wound produce proteases, including matrix metalloproteinases (MMPs), that degrade the extracellular matrix (ECM) and growth factors necessary for healing. Chronic wounds often harbor bacterial colonies that form biofilms—polymicrobial communities embedded in a self-produced polymeric matrix. These biofilms provide an ideal environment for bacterial survival, enabling the bacteria to evade immune defense mechanisms and resist antibiotic treatments. Although biofilms are common in chronic wounds and have been shown to delay re-epithelialization in animal models, the exact mechanisms by which they hinder healing are still not fully understood.

It is hypothesized that the increased survival of bacteria and enhanced production of virulence factors contribute to healing delays. Moreover, the extracellular components of biofilms may have a toxic effect on host cell function, further impeding the healing process. Recent studies have shown that disrupting biofilm formation with RNAIII inhibiting peptide can reverse healing delays caused by biofilms. A better understanding of how biofilms interfere with wound repair, coupled with improved methods for detecting and preventing biofilm formation, may provide valuable opportunities for promoting active healing in chronic wound beds.

Cytokines and growth factors such as VEGF and PDGF coordinate transitions between phases¹³. Chronic wounds arise when this sequence is disrupted due to excess matrix metalloproteinases, ischemia, necrosis, or infection¹⁴⁻¹⁶. Effective wound dressings protect, maintain moisture, minimize pain, and promote epithelialization¹⁷⁻¹⁸. Collagen dressings, especially in granule form, have gained importance for their scaffolding, angiogenic, and MMP-modulating properties¹⁹⁻²². In diabetic foot ulcers, these dressings help preserve extracellular matrix and reduce inflammation or infection risk²³⁻²⁵.

OBJECTIVES

1)To study the effect of antibiotic coated collagen granules and conventional 5% povidine iodine dressing on chronic wounds.

2)To compare the efficacy of antibiotic coated collagen granules and conventional 5% povidine iodine dressing in reduction of wound size and time taken for wound to             contract.

3)To compare the outcome of antibiotic coated collagen granules and conventional 5%         povidine iodine dressing in management of chronic wounds.

Conclusion:

Collagen dressings are valuable tools in wound management due to their ability to create an optimal healing environment by supporting granulation tissue formation, enhancing cellular migration, and promoting wound closure. The different forms of collagen, combined with additional materials like gels, alginates, and antimicrobial agents, allow these dressings to be tailored for specific wound care needs. Their moisture-retaining properties, flexibility, and ability to promote granulation and epithelialization make them particularly effective for chronic, acute, and traumatic wounds.

RESULTS

This interventional study compared the efficacy and clinical outcomes of conventional 5% povidine-iodine dressing (Group A) against antibiotic-coated collagen granules dressing (Group B), each with 88 patients. Non-parametric tests were used due to non-normal distributions.

Demographics and Baseline Characteristics

Table 1: Patient Demographics by Treatment Group

Interpretation: Both groups were predominately male. Group A had a higher percentage of older patients (51-60 years), while Group B had more young adults (21-30 years). Both groups (n=88 each) were predominantly male; Group A (povidone-iodine) skewed slightly older than Group B (collagen granules), consistent with typical chronic wound populations²⁶.

Wound Surface Area Reduction

Table 2: Wound Surface Area Before and After Treatment

Interpretation: Both groups demonstrated significant wound surface area reduction (Wilcoxon p<0.001 each), but collagen granule treatment produced a larger decrease (Z = -8.143 for Group B vs Z = -4.099 for Group A)²⁷. Direct comparison (Mann-Whitney U = 730.0, p<0.001) confirmed the superior wound reduction with collagen granules²⁸.

Between-Group Comparison of Wound Surface Area Change

Table 3: Comparison of Wound Surface Area Change

Interpretation: Group B had a significantly greater reduction in wound area compared to Group A.

Clinical Progression and Treatment Efficiency

Table 4: Key Clinical Outcome Measures

Interpretation: Group B patients reached readiness for split-thickness skin grafting (SSG) in fewer days (U = 548.5, p<0.001), required fewer dressing changes (U = 704.0, p<0.001), and had shorter hospital stays (U = 983.5, p<0.001), aligning with other reports on biologic dressings¹³˒²⁹⁻³⁰.

Overall Comparative Outcomes

Table 5: Summary of Outcomes Comparing Conventional vs. Collagen Granule Dressings

Both dressings effectively reduced wound size, but antibiotic-coated collagen granules showed superior wound healing outcomes.

Collagen granules allowed faster readiness for grafting and required fewer dressings, indicating more efficient wound care.

Patients with collagen dressing spent fewer days in hospital, reducing healthcare burden.

over the traditional povidine-iodine approach for chronic wounds.

This study affirms that both povidone-iodine and antibiotic-coated collagen granule dressings significantly improve chronic wound outcomes, but collagen granules offer greater clinical benefits. Wound area reduction was greater, dressing frequency was lower, readiness for grafting was sooner, and hospital stays were shorter with

collagen granules—findings that echo prior randomized and clinical reports¹⁹˒²².

These outcomes highlight the benefits of collagen dressings, which support extracellular matrix formation, modulate inflammation, and reduce infection risk through antibiotic coating. The findings support collagen granules as a superior wound care option, potentially improving patient outcomes and reducing healthcare resources.

Further large-scale studies are recommended to confirm these results and evaluate cost-effectiveness across diverse wound types.

Role of Collagen in Wound Healing and the Use of Collagen Granules in Diabetic Foot Ulcers

Collagen’s advantage is rooted in its ability to modulate MMP activity, stimulate granulation, foster angiogenesis, maintain moisture, and protect against infection—especially when combined with antimicrobials²³˒²⁴. This supports the use of collagen granules in diabetic ulcers and other chronic wounds, as reflected in several clinical guidelines and meta-analyses.

How Collagen Granules Address Wound Healing Challenges:

• MMP Modulation: Collagen granules act as sacrificial substrates, diverting MMP activity from viable tissue.
• Cell Recruitment: Degradation products of collagen stimulate chemotaxis and cellular infiltration, aiding granulation.
• Moisture Regulation: Collagen dressings help maintain a moist wound environment, favorable for cell proliferation and migration.
• Antimicrobial Support: Some formulations incorporate antimicrobial agents, helping control wound bioburden.
• Structural Matrix: Collagen acts as a matrix for angiogenesis and tissue regeneration.
• Microenvironment Support: These dressings support a physiological wound environment, aiding in overall healingy.

Despite these benefits, collagen granules are not a substitute for the gold standard in diabetic wound care, which includes etiology identification, infection management, ensuring adequate vascular supply, regular debridement, and offloading. Advanced therapies, such as growth factors and living-skin equivalents, are under clinical investigation and are typically used alongside dressings, not as replacements. The combination of newer therapies with collagen dressings may enhance healing potential, though further research is needed.

Moreover, the inclusion of antibiotics within the collagen matrix appears to have enhanced the therapeutic benefits by reducing local microbial load—a key factor in chronic wound persistence. Chronic wounds are frequently colonized by biofilm-producing bacteria, which impair healing by disrupting host immune responses and degrading growth factors and ECM components. Studies have shown that topical antimicrobials, when delivered through sustained-release carriers such as collagen, reduce bacterial burden while maintaining a moist wound environment conducive to healing.

Our study corroborates findings by Mulder et al. and Chattopadhyay et al., who reported significantly improved wound healing rates in chronic ulcers treated with collagen-based dressings, particularly when used in conjunction with antimicrobials or growth factors. Additionally, collagen has been shown to downregulate proteolytic activity (e.g., matrix metalloproteinases), which is often elevated in non-healing ulcers, thereby preserving essential ECM elements and supporting tissue regeneration.

Although current studies suggest benefit, the evidence base is limited and lacks sufficient randomized controlled trials. Moreover, no particular biological collagen source has proven superior. Future investigations should consider biofilm activity and matrix-targeting strategies, with an emphasis on vulnerable patient populations to ensure clinical relevance.

However, further large-scale trials are warranted to confirm these benefits across diverse populations and to assess cost-effectiveness.

Based on the statistical analysis and clinical outcomes observed in this study, it is evident that antibiotic-coated collagen granule dressings offer significant advantages over conventional 5% povidone-iodine dressings in the management of chronic wounds. These include:

• Significant reduction in wound surface area
• Shorter time interval before split skin grafting (SSG)
• Fewer dressing changes required
• Reduced duration of hospital stay

These findings are consistent with prior studies indicating that collagen-based dressings enhance wound healing by providing a scaffold for cellular migration and supporting the action of growth factors critical for granulation and re-epithelialization processes.

Collagen dressings have also been shown to reduce matrix metalloproteinase (MMP) activity and modulate the wound microenvironment to support angiogenesis and epithelial proliferation. The incorporation of antibiotics into collagen granules further improves their efficacy by minimizing local infection, a common cause of delayed healing in chronic wounds.

Antibiotic-coated collagen granule dressings outperform traditional 5% povidone-iodine dressings for chronic wounds, delivering larger wound reductions, faster healing, fewer dressings, and shorter hospitalizations. Collagen granules' structural and bioactive properties justify their adoption in advanced wound care, especially for patients with diabetic foot ulcers or hard-to-heal wounds. Ongoing research will clarify their optimal use in combination therapies and broader clinical settings.

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