Wound healing is an essential process that allows the skin and underlying tissue to recover after injury. In modern medicine, understanding this process is crucial to developing effective treatment strategies and avoiding complications such as infection or chronic wounds.
Overview of the role of collagen in the body
Collagen is the most abundant protein in the human body and forms the structural basis for skin, bones, tendons and ligaments. It gives tissue strength and elasticity and plays a central role in wound healing by serving as a scaffold for the formation of new tissue.
Basics of wound healing
Phases of wound healing
Wound healing takes place in several overlapping phases, each of which involves specific cellular and molecular processes:
Hemostasis phase
Haemostasis starts immediately after an injury to stop bleeding. Thrombocytes (blood platelets) aggregate at the site of the injury and form a temporary plug. At the same time, a cascade of coagulation factors is activated, which leads to the formation of a stable fibrin network that forms the basis for the subsequent healing processes. Collagen is involved here: when certain integrin receptors recognise exposed collagen, the thrombocytes are activated, and the activation and aggregation of the thrombocytes leads to the fibrin clot.¹
Inflammatory phase
During this phase, immune cells such as neutrophils and macrophages are recruited to the wound to eliminate pathogenic microorganisms and remove cell debris. Macrophages also release cytokines and growth factors that promote fibroblast proliferation and angiogenesis. Fragments of type I and IV collagen can act as chemoattractants for neutrophils, boosting phagocytosis and the immune response.²
Granulation phase
The granulation phase is characterized by the formation of new connective tissue and blood vessels. Fibroblasts proliferate and synthesize collagen, especially type III, which serves as a temporary scaffold. At the same time, new capillaries sprout into the wound bed to ensure the supply of nutrients and oxygen. In laboratory and in vivo models, type I collagen stimulated angiogenesis; binding to specific integrin receptors (α1β1/α2β1) on endothelial cells appears to be crucial.³
Epithelialization phase
During this phase, epithelial cells migrate from the wound edge over the granulation tissue to close the wound. The synthesis of type I collagen increases, which helps to strengthen the newly formed tissue. Collagen encourages the migration of keratinocytes here, through which the wound is re-covered with epithelium.¹
Maturation phase
In the final phase of wound healing, the collagen network is restructured. Type III collagen is replaced by the more stable type I, and the collagen fibers orient themselves along the tension lines in order to increase the mechanical resilience of the tissue. This process can take several months to years. Even a normally healed acute wound only reaches about 80 % of the mechanical properties the skin had before the injury.⁴
Factors influencing wound healing
Age and state of health
With increasing age, many regenerative processes in the body slow down, including wound healing. Among other things, this is due to reduced cell proliferation and collagen synthesis. In addition, age-related diseases such as diabetes mellitus or arterial occlusive diseases can further impair healing.
Diet and lifestyle
A balanced diet is crucial for effective wound healing. Proteins provide the necessary amino acids for the formation of new tissue, while vitamins and minerals such as vitamin C, zinc and iron act as cofactors in various phases of healing. A deficiency of these nutrients can significantly delay the healing process. Protein malnutrition is associated with delayed or failed wound healing; in a study in rats, wounds healed less well on a diet with gluten as the protein source than on casein.⁵
Presence of infections or chronic diseases
Infections can significantly disrupt the healing process by increasing inflammatory reactions and inhibiting tissue regeneration. Chronic diseases such as diabetes mellitus lead to reduced blood flow and nerve function, which makes wound healing even more difficult. Effective control of blood glucose levels and appropriate wound care are therefore essential for healing in diabetic patients.
Collagen: structure and function
Structure and types of collagen
Collagen is the most abundant protein in the human body and forms the structural basis for skin, bones, tendons and ligaments. There are at least 28 different types of collagen, with types I, II and III being the most common. Type I is mainly found in skin, tendons and bones, type II in cartilage and type III in the skin and blood vessels. The collagen molecules consist of three polypeptide chains that form a triple helix; properties such as mechanical strength derive from this basic structure.⁶
Five collagen types (I, II, III, V, X) in one product. Our multi collagen powder is a food supplement taken by mouth — it has nothing to do with the medical wound dressings described here. 100% pure, without additives and tasteless.
Role of collagen in tissue formation
Collagen not only provides structural integrity to tissue, but also plays an active role in cell migration, differentiation and the healing process. During wound healing, it serves as a scaffold for cell proliferation and the formation of new extracellular matrix. Collagen is therefore one of the structural components involved in tissue regeneration.
Types of collagen wound dressings
Collagen films
Collagen films are thin, flexible layers of collagen that are applied directly to the wound. They form a physical barrier over the wound and keep the wound area moist. Thanks to their transparency, they allow easy wound inspection without removing the film. Film dressings can stay on the wound for up to seven days, depending on its size, type and location.⁷
Collagen gels
Collagen gels are moist, viscous substances that are applied to the wound. They give the wound moisture.
Collagen pads
Collagen pads are thicker, absorbent dressings that absorb excess exudate and simultaneously supply the wound with collagen. They are particularly suitable for moderately to heavily exuding wounds and provide good padding. Collagen acts as a natural substrate for cell attachment and proliferation; in a limited study, a collagen sponge used as a cell-free matrix promoted new tissue formation.⁸
Collagen particles
Collagen particles are small, granulated forms of collagen that are introduced into deep or irregular wounds. They fill the wound cavity. Because they are ground, they have a larger contact area with the wound and cover it better.⁷
Mechanisms of collagen action in wound healing
Cell proliferation and migration
Collagen serves as a scaffold on which cells move and multiply. Collagen type I in particular attracts fibroblasts, which are responsible for the formation of new tissue. Reviews describe how a new, collagen-rich extracellular matrix is built during healing, into which fibroblasts migrate.⁹
Collagen peptides taken by mouth are a different thing: our marine collagen powder is a food supplement. It supplies amino acids; it is not a wound dressing, and the applications described above belong in a clinician's hands.
Collagen and angiogenesis
The formation of new blood vessels is crucial for supplying the healing tissue with nutrients and oxygen. Type I collagen is part of the matrix in which endothelial cells arrange themselves as new vessels form. Collagen and thrombocytes act together here: after platelet aggregation, the thrombocytes release growth factors such as vascular endothelial growth factor (VEGF) that stimulate endothelial cells to proliferate and migrate.⁷
Collagen and the inflammatory response
A balanced inflammatory process is essential for healing. Collagen interacts with matrix metalloproteinases (MMPs), the enzymes that break down tissue. Dressings made of collagen and oxidised regenerated cellulose are described as binding and inactivating matrix metalloproteinases in the wound environment, thereby protecting growth factors.¹⁰
Collagen dressings and the body's own collagen formation
Collagen wound dressings bring collagen directly into the wound. According to a systematic review, collagen-containing wound dressings form a biological scaffold matrix in the wound bed.¹¹
Clinical applications of collagen wound dressings
Treatment of chronic wounds
Diabetic foot ulcers
Diabetic foot ulcers are a common complication of diabetes mellitus. One study compared collagen wound dressings with a control group in diabetic foot ulcers. In a randomised study of 30 patients, 82.4 % of ulcers healed completely with a 100 % collagen dressing plus foam dressing (14 of 17), compared with 38.5 % with foam dressing alone (5 of 13).¹²
Decubitus ulcers (pressure sores)
Pressure ulcers are caused by prolonged pressure on certain areas of the body, especially in immobilized patients. Collagen wound dressings are used here to keep the wound environment moist.
Ulcus cruris (open leg)
Collagen wound dressings are also used for ulcus cruris, which is often caused by venous insufficiency.
Use for acute wounds
Surgical incisions
Collagen dressings are also used after surgical procedures. Commercially available collagen wound dressings are intended, among other uses, for the care of surgical wounds.¹
Traumatic injuries
For traumatic wounds such as cuts or lacerations, collagen wound dressings cover the wound. They act as a scaffold that cells can move into.
Second degree burns
Second-degree burns require careful wound care. Collagen wound dressings are used here to keep the wound environment moist. They are applied by medical staff as part of a treatment plan.
Use for skin grafts and donor sites
Collagen dressings are also used after skin grafts and at donor sites. Collagen sponges are described as suitable for, among other things, skin graft donor sites.¹
Properties of collagen wound dressings
Moist wound environment
A moist wound environment is crucial for optimal healing. Collagen wound dressings absorb exudate and keep the wound moist; this is the environment in which cells migrate.
Scarring
Reviews name the prevention of scarring as one of the reasons collagen-based hydrogels are being studied as wound dressings; part of the data on this comes from animal models.¹
Biocompatibility and resorbability
Collagen is a natural component of the human body. In addition, collagen wound dressings are absorbed by the body, which reduces the need for frequent dressing changes.
Covering the wound
Collagen wound dressings form a physical barrier over the wound. Some products also contain antimicrobial substances.
Contraindications and precautions
Unsuitable wound types for collagen dressings
Not every wound benefits from collagen dressings. Caution is required, particularly in the case of dry necrosis and third-degree burns. In such cases, the application of collagen may not only be ineffective but may even hinder the healing process. The use of collagen wound dressings should also be avoided in cases of active vasculitis. In addition, caution is advised in the case of known allergies to animal collagen, particularly from bovine or porcine sources. Although most products are well tolerated, allergic reactions can occur in rare cases.
Combination options with other therapies
Modern wound care increasingly relies on combined therapies to maximize the chances of healing.
Integration with antimicrobial substances
Collagen dressings are also available combined with antimicrobial substances. One example of this is the combination with silver, which has an antimicrobial effect. Such combination products are mainly used for infected wounds.
Use in combination with growth factors
Collagen is also used together with growth factors, for example platelet-rich plasma (PRP). These approaches are mainly being tried in chronic wounds that do not respond to conventional treatments.
Use together with modern technologies such as cold plasma
An innovative combination is the use of collagen wound dressings with cold plasma. Cold plasma is used as an antiseptic, while the collagen dressing keeps the wound moist.
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Conclusion
Collagen wound dressings are a wound-care tool that belongs in a clinician's hands. However, it is important to consider the specific characteristics of the wound and possible contraindications. They can be combined with other therapies, such as antimicrobial substances, growth factors or cold plasma. Talk to your doctor or wound expert to find the right therapy for you.