A Review of Collagen and Collagen-based Wound Dressings

David Brett, BS, BS, MS

Disclosures

Wounds. 2008;20(12) 

In This Article

Collagen-based Wound Dressings

There are a number of different collagen dressings available, which employ a variety of carriers/combining agents such as gels, pastes, polymers, oxidized regenerated cellulose (ORC), and ethylene diamine tetraacetic acid (EDTA). The collagen within these products tends to be derived from bovine, porcine, equine, or avian sources, which is purified in order to render it nonantigenic. The collagen in a given collagen dressing can vary in concentration and type. Certain collagen dressings are comprised of Type I (native) collagen; whereas, other collagen dressings contain denatured collagen as well. A given collagen dressing may contain ingredients, such as alginates and cellulose derivatives that can enhance absorbency, flexibility, and comfort, and help maintain a moist wound environment. Collagen dressings have a variety of pore sizes and surface areas, as well. All of these attributes are meant to enhance the wound management aspects of the dressings. Many collagen dressings contain an antimicrobial agent to control pathogens within the wound. Collagen dressings typically require a secondary dressing (see Appendix I for a summary of currently available collagen-based wound dressings).

Mode of action (MoA). Research has shown that some collagen-based dressings produce a significant increase in the fibroblast production; have a hydrophilic property that may be important in encouraging fibroblast permeation; enhance the deposition of oriented, organized collagen fibers by attracting fibroblasts and causing a directed migration of cells; aid in the uptake and bioavailability of fibronectin; help preserve leukocytes, macrophages, fibroblasts, and epithelial cells; and assist in the maintenance of the chemical and thermostatic microenvironment of the wound.[16,17,18,19,20] The MoA of several collagen dressings includes the inhibition or deactivation excess MMPs. As mentioned, excess MMPs are a key contributor to wound chronicity. The MoA of collagen dressings is described in Figures 6-13.

The role of collagen dressings in chronic wound care. Here, a traditional collagen based wound dressing has been placed into the chronic wound. Being a chronic wound, there is an overabundance of MMPs and a decrease in the number of TIMPs. There senescence of the wound cells adds to the chronicity allowing the wound to increase in size.

The effects of collagen-based wound dressing MMP activity. Since MMPs attack and break down collagen, a portion of them migrate toward the collagen based dressing and start to degrade it. The degradation products cal lin other cells such as fibroblasts and endothelial cells necessary fot the formation of granulation tissue.

MMPs degrade collagen-based wound dressings. However, as the collagen dressing is degraded by the MMPs, it is broken down and releases active MMPs back into the wound.

The role of collagen and EDTA in chronic wound care. Here, a collagen based wound dressing containing EDTA has been placed into the chronic wound. Being a chronic wound, there is an overabundance of MMPs and a decrease in the number of TIMPs. The sensecence of the wound cells adds to the chonicity allowing the wound to increase in size.

The effects of collagen and EDTA on MMP activity. EDTA (a chelating agent depicted here in blue) permanently deactivates a portion of the MMPs preventing them from degrading collagen, and since MMPs attack and break down collagen, a portion of them migrate toward the collagen based dressing and start to degrade it. As the collagen dressing is degraded, MMPs are released back into the wound, a portion of which has been deactivated by EDTA.

MMPs degrade collagen-based wound dressings. The degradation products call in other cells, such as fibroblasts and endothelials, necessary for the formation of granulation tissue.

An overview of the role of fibroblasts and endothelial cells during granulation. As a result, the level of active MMPs is reduced to a level that allows fibroblasts to proliferate, lay down new collagen (and other fibrous proteins), and to secrete glycosaminoglycans (GAGs), resulting in a functional ECM. The collagen fragments have also activated endothelial cells to propogate and create new blood vessels. With a functional ECM and a blood supply, granulation is achieved.

Overview fo the role of keratinocytes in wound closure. Keratinocytes (red colored cells) from the wound margin migrate across the functional granulation tissue initiating the process of re-epithelialization. Re-epithelialization will continue until the epidermis is full. The next phase of healing is the remodeling phase; wherein, fibroblasts will remodel and cross-link the collagen fibers to make a stronger scar.

Comments

3090D553-9492-4563-8681-AD288FA52ACE
Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.
Post as:

processing....