The Science of Collagen

Collagen is a protein with unique chemistry and specific functions. In its native form, collagen has many responsibilities in the body – such as aiding cellular activity and providing an organized matrix in the skin. An understanding of collagen’s chemical, physical, and biological properties will help clinicians utilize collagen technology effectively in their wound care protocols.
Collagen is a natural biomaterial present in all animals. In its native form, collagen has biological properties which provide functional integrity to body tissues.

Properties of Collagen

Collagen Molecule Chemistry

Collagen in the Body:

  • A structural protein with unique chemistry
  • Provides structure and integrity to most body tissues.[1]
  • Distribution and orientation reflects tissue function.[2]
  • Must be in native form to elicit biological functions.

Molecules Self-Assemble into Fibers

Collagen in the Proper Form:

  • Chemistry consists of helical and non-helical domains.[4]
  • Molecules must be complete to provide an appropriate biological response.
  • Self-assembled molecules form fibers and aggregates.[5]
  • Intact fibers promote cell growth, activity, and migration.[3]

Fibers form Aggregates

  • Chemistry consists of helical and non-helical domains.[4]
  • Molecules must be complete to provide an appropriate biological response.
  • Self-assembled molecules form fibers and aggregates.[5]
  • Intact fibers promote cell growth, activity, and migration.[3]

Aggregates Become Skin Tissue

Human & Bovine Collagen:

  • Human collagen varies because producing exact duplicates may be biologically uneconomical.[8]
  • The composition of bovine collagen is within the range of variance of collagen duplicated in human tissues.[8]
  • Amino acid chain sequences are similar.[8]

Collagen Fibril Structure

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

Bovine Collagen

Collagen in Proper Form

Collagen vs Non-Collagen

(Histology photos taken from adult miniswine) Collagen 20 weeks at 20 x magnification When improper form, collagen is replaced by newly deposited collagen (blue) in the body.
Collagen has specific chemistry, structure, and aggregate structure. In its native form, collagen has functional and biological properties which are lacking in proper collagen and other materials.

Collagen in the Proper Form

  • Contains complete molecules.[4]
  • Contains fibril with a banding pattern.[5]
  • Forms aggregates[9] with rope-like structure.
  • Has structural and biological properties of native collagen.[3.5]
Collagen Composite 20 weeks at 20 x magnification Produces a response that is similar to new non-collagen materials. There’s a lack of newly deposited collagen (blue) and a presence of foreign body giant cells (purple).

Collagen in Improper Form

  • Fails to meet the scientifically accepted definition of collagen.
  • Has a regular structure, resembling that of non-collagen materials.
  • Exhibits biological responses that are analogous to non-collagen materials.
  • Lacks functional properties of collagen.[2]
Alginate 20 weeks at 20 x magnification Other materials can cause foreign body responses (purple).

Other Materials

  • Lacks biological form and function.
  • Provides an artificial environment.
  • These non-collagen materials are not natural to the human body.[10]

References:

  1. Kucharz E, The Collagens: Biochem. & Pathophys. Berlin: Springer-Verlag, 1992.
  2. Miller A. in Viidik, A. & Vuust, J. (eds.), Biology of Collagen. London: Academic Press; 1980.
  3. Reddi AH in Ramachandran, GN & Reddi AH (eds.), Biochemistry of Collagen. New York: Plenum Press;1976.
  4. Hannig K, et al., in Ramachandran, GN (ed.) Treatise on Collagen (Vol 1). London: Academic Press; 1967.
  5. Kuhn K, et al., in Viidik A. & Vuust J. (eds.), Biology of Collagen. London: Academic Press; 1980.
  6. Chiang TM, et al., J Clin. Invest. 1977;59:405 411.
  7. Kleinman HK, et al., BioChem. 1981;20:2325-2330.
  8. Eastoe JE, in Ramachandran GN (ed.) Treatise on Collagen (Vol 1). London: Academic Press; 1967.
  9. Jackson SF, in Gould BS (ed.) Treatise on Collagen (Vol 2). London: Academic Press, 1968.
  10. Chvapil M, J Biomed. Mat. Res. 1982;16:245-263.