Collagen

Collagen is a protein with unique chemistry and a specific function. In the proper form, collagen has many responsibilities in the body, including aiding cellular activity and providing an organized matrix in skin. An understanding of collagen's chemical, physical, and biological properties will help clinicians utilize collagen technology effectively in their wound care practice and protocols.

Collagen's Role in Healing

Collagen molecule chemistry

Collagen in the Body

  • A structural protein with unique chemistry.
  • Provides structure and integrity to most body tissues.
  • Distribution and orientation reflect tissue function.
  • Must be in the proper form to elicit biological functions.

Molecules self assemble into fibers

Collagen in the Proper Form

  • Chemistry consists of helical and nonhelical domains.
  • Molecules must be complete to provide an appropriate biological response.
  • Self-assembled molecules form fibers and aggregates.
  • Intact fibers cause cell growth, activity, and migration.
  • Aggregates have specific binding sites for cells and cell­ binding proteins in the body, resulting in strong, healthy tissues.

Aggregates become skin tissue

Human and Bovine Collagen

  • Collagen is a natural biomaterial present in all animals.
  • Human collagen varies because producing exact duplicates may be biologically uneconomical.
  • The composition of collagen in bovine is within the range of variance of collagen duplicated in human tissues.
  • Amino acid chain sequences are similar.

Human and Bovine Collagen

Transmission electron microscopy illustrates that the structure of bovine collagen fibers presented in textbooks, (left) closely resembles the structure of fibers found in dressings containing collagen in its proper form. (right)

Bovine Collagen

These fibrils are 0.5 µm in diameter with repeat structural units that result in periodic striations

Collagen in Proper Form

These fibrils are 0.5 µm in diameter. Fibrils self assemble to form fibers and aggregates.

Collagen vs. Non-Collagen

Collagen has specific chemistry, fibrillar structure, and aggregate structure. In the proper form, collagen has functional and biological properties which are lacking in improper collagen and other materials.

Collagen: 20 weeks ar 20x magnification

When in the proper form, collagen is replaced by newly deposited collagen (blue) in the body

Collagen in the Proper Form

  • Contains complete molecules.
  • Contains fibrils with banding pattern.
  • Forms aggregates 9 with rope-like structure.
  • Has structural and biological properties of native collagen

Collagen composite: 20 weeks at 20x magnification

Produces a response that is similar to non­ collagen materials. There is a lack of newly deposited collagen (blue) and a presence of foreign body giant cells (purple).

Collagen in Improper form

  • Fails to meet scientifically accepted definition of collagen.
  • Has irregular structure, resembling that of n on-collagen materials.
  • Exhibits biological responses that are analogous to non -collagen materials.
  • Lacks functional properties of collagen

Alginate: 20 weeks at 20x magnification

Other materials can cause foreign body responses

Other Materials

  • Lack biological form and function.
  • Provides an artificial environment .
  • These non -collagen mate rials are not natural to the human body.

Collagen Aggregates & Structure

Collagen in the proper form has an ordered structure

Proper Form

Fibers self assemble into aggregates which resemble rope-like structures


Improper Form

Soluble collagen: Lacks nonhelical domains, forms disorganized fibrils

Insoluble Collagen: No ordered structural matrix.


Other materials

Simple hydrogel: Lacks any organized structure


Glossary

  • Apoptosis: Death of cells as a normal controlled part of organism growth and development.
  • Amino Acid: Any organic compound containing an amino and a carboxyl group.
  • Alginate: Alginates consist of the soft, non-woven fibers of a cellulose-like polysaccharide derived from the seaweed's calcium salts. They are biodegradable, hydrophilic, non-adherent, and highly absorbent.
  • Collagen: The most prevalent protein in the animal kingdom responsible for the structure and integrity of most tissues. A protein containing domains of triple-helical conformation. Characterized by repetitive Gly­-X-Y sequences where glycine is in every third residue and stabilized by proline and hydroxyproline residues. A protein that participates in the formation of extra­cellular aggregates, which are primarily supporting elements.
  • Collagen Fibers/Fibrils: Delicate fibers or fibrils of collagen in connective tissue, usually cemented together in wavy bundles.
  • Hydrogel: A gel that has water as its dispersion medium. Hydrogel is used to donate moisture to wounds and provide an optimal moist environment enhancing healing progress.
  • Protein: Any group of complex organic compounds containing carbon, hydrogen, oxygen, nitrogen, usually sulfur, is widely distributed in plants and animals. Twenty different amino acids are commonly found in proteins. Each protein has a unique, genetically defined amino acid sequence which determines its specific shape and function.