By Dr Ananya Mandal, MD
Collagens are the most abundant tissues in nature and due to several properties they are considered for various applications in biomedical sciences.
Some of the medical uses include cosmetic surgery, reconstructive surgery and so forth.
Use of collagen in cosmetic surgery
Collagen is used widely in cosmetic surgery and as wound healing aids in burn patients. These are used widely for reconstruction of bone and a wide variety of dental, orthopedic and surgical purposes.
Most of the medical collagen used is young beef cattle (bovine) from certified BSE (Bovine spongiform encephalopathy) free animals. Donor animals are from "closed herds", or from countries which have never had a reported case of BSE such as Australia, Brazil and New Zealand.
Another commonly used tissue is porcine (pig) tissue. This is used for producing collagen sheet for a variety of surgical purposes. In some patients, the patient's own fat, hyaluronic acid or polyacrylamide gel are also used.
Collagen is used as sheets, dermal filler etc. in cosmetic procedures. Although it cannot be absorbed through the skin, collagen is now being used as a main ingredient for some cosmetic makeup.
Collagen in reconstructive surgeries
Collagen can be used in the construction of artificial skin substitutes used in the management of severe burns. This may be derived from bovine (cows), procine (pigs), equine (horses) or even human sources and are sometimes used in combination with silicones, glycosaminoglycans, fibroblasts, growth factors and other substances.
Human collagen is derived from donor cadavers, placentas and aborted foetuses and has a low possibility of immune reactions.
Collagen is sold as a pill as a supplement to help with joint mobility. However, since proteins are broken down into amino acids before absorption, an orally taken pill may not really affect connective tissue in the body, except through the effect of individual amino acid supplementation.
Collagen in scientific research
Collagen is also frequently used in scientific research applications for cell culture, studying cell behavior and cellular interactions with the extracellular environment.
Collagen in cardiology
The heart valves are made up of collagen tissue. Individual valvular leaflets are held in shape by collagen under variable pressure. In addition, with aging there is calcium deposit on the collagen leading to hardening of the valves.
Collagen as barrier films and sheets/discs
The main application of collagen ﬁlms is as barrier membrane. Films with the thickness of 0.01 – 0.5 mm and made of biodegradable materials. The drugs can be loaded into collagen membranes by hydrogen bonding, covalent bonding or simple entrapment. They can be sterilized and become made flexible. This are used in ophthalmology in delivering drugs to the yes and also used over wounds to make healing rapid and uniform.
These are used as bandage contact lenses that gradually dissolve in cornea. This idea has led to the development of more drug delivery systems for ophthalmic applications. One of the advantages is ease of application and self administration.
These are very useful in the treatment of severe burns and as a dressing for many types of wounds, such as pressure sores or bed sores, donor sites from where skin grafts have been taken, surgical sites, leg ulcers etc.
These have the capacity to absorb large amounts of tissue secretions, lead to smooth adherence to the wet wound and maintain a low-moisture climate in the wound and shield against mechanical harm and secondary bacterial infection.
Gel, hydrogel, liposomes-collagen
These are used as vehicles for drug delivery. They are often combined with synthetic polymers for drug delivery. The combination of natural and synthetic polymers may provide mechanical stability and biological acceptability, acquiring from synergistic properties of both materials.
Collagen pellets or tablets
Minipellets made of collagen have been developed. These are used in drug delivery systems. The minipellet is small enough to be injected into the subcutaneous space through a syringe needle and large enough to contain large molecular weight protein drugs, such as interferon.
These microscopic molecules also act as drug delivery systems as colloidal drug delivery carriers.
Collagen as bone substitutes
Collagen has been used as implantable carriers for bone inducing proteins and has been used as bone substitutes due to its osteo-inductive activity. Collagen ﬁlm may be used as gene delivery carriers for osteoinduction and collagen sponge may be used for bone related protein carriers.
Reviewed by April Cashin-Garbutt, BA Hons (Cantab)