Tuesday, May 7, 2013

Collagen, What It Is and What It Does for Us



Collagen
From Wikipedia, the free encyclopedia
Collagen is a group of naturally occurring proteins is the main component of connective tissue, and is the most abundant protein making up about 25% to 35% of the whole-body protein content. Collagen, in the form of elongated fibrils, is mostly found in fibrous tissues such as tendon, ligament and skin, and is also abundant in cornea, cartilage, bone, blood vessels, the gut, and intervertebral disc. The fibroblast is the most common cell which creates collagen. In muscle tissue, it serves as a major component of the endomysium. Collagen constitutes one to two percent of muscle tissue, and accounts for 6% of the weight of strong, tendinous muscles.[3] Gelatin, which is used in food and industry, is collagen that has been irreversibly hydrolyzed.

Types and associated disorders

Collagen occurs in many places throughout the body. Over 90% of the collagen in the body, however, is of type I.[37]

So far, 28 types of collagen have been identified and described. The five most common types are:

Collagen I: skin, tendon, vascular ligature, organs, bone (main component of the organic part of bone)
Collagen II: cartilage (main component of cartilage)
Collagen III: reticulate (main component of reticular fibers), commonly found alongside type I.
Collagen IV: forms bases of cell basement membrane
Collagen V: cell surfaces, hair and placenta
Collagen-related diseases most commonly arise from genetic defects or nutritional deficiencies that affect the biosynthesis, assembly, postranslational modification, secretion, or other processes involved in normal collagen production.

Genetic Defects of Collagen Genes
Type
Notes
Gene(s)
I
This is the most abundant collagen of the human body. It is present in scar tissue, the end product when tissue heals by repair. It is found in tendons, skin, artery walls, cornea, the endomysium of myofibrils, fibrocartilage, and the organic part of bones and teeth.
Hyaline cartilage, makes up 50% of all cartilage protein. Vitreous humour of the eye.
This is the collagen of granulation tissue, and is produced quickly by young fibroblasts before the tougher type I collagen is synthesized.Reticular fiber. Also found in artery walls, skin, intestines and the uterus
Basal laminaeye lens. Also serves as part of the filtration system incapillaries and the glomeruli of nephron in the kidney.
V
Most interstitial tissue, assoc. with type I, associated with placenta
VI
Most interstitial tissue, assoc. with type I
VII
VIII
Some endothelial cells
IX
FACIT collagen, cartilage, assoc. with type II and XI fibrils
X
Hypertrophic and mineralizing cartilage
XI
Cartilage
XII
FACIT collagen, interacts with type I containing fibrils, decorin and glycosaminoglycans
XIII
Transmembrane collagen, interacts with integrin a1b1, fibronectinand components of basement membranes like nidogen and perlecan.
XIV
XV
XVI
Transmembrane collagen, also known as BP180, a 180 kDa protein
Source of endostatin
XIX
XX
XXI
XXII
XXIII
MACIT collagen
XXIV
XXV
XXVI
XXVII
XXVIII





In addition to the above mentioned disorders, excessive deposition of collagen occurs in scleroderma.
Diseases [edit]
One thousand mutations have been identified in twelve out of more than twenty types of collagen. These mutations can lead to various diseases at the tissue level.[39]
Osteogenesis imperfecta – Caused by a mutation in type 1 collagen, dominant autosomal disorder, results in weak bones and irregular connective tissue, some cases can be mild while others can be lethal, mild cases have lowered levels of collagen type 1 while severe cases have structural defects in collagen.[40]
Chondrodysplasias – Skeletal disorder believed to be caused by a mutation in type 2 collagen, further research is being conducted to confirm this.[41]
Ehler-Danlos Syndrome – Ten different types of this disorder which lead to deformities in connective tissue, some types can be lethal that lead to the rupture of arteries, each syndrome is caused by a different mutation, for example type four of this disorder is caused by a mutation in collagen type 3.[42]
Alport syndrome – Can be passed on genetically, both an autosomal dominant and autosomal recessive disorder, sufferers have problems with their kidneys and eyes, loss of hearing can also develop in during the childhood or adolescent years.[43]
Osteoporosis – Not inherited genetically, brought on with age, associated with reduced levels of collagen in the skin and bones, growth hormone injections are being researched as a possible treatment to counteract any loss of collagen.[44]
Knobloch syndrome – Caused by a mutation in the collagen XVIII gene, patients present with protrusion of the brain tissue and degeneration of the retina, an individual who has family members suffering from the disorder are at an increased risk of developing it themselves as there is a hereditary link.[39]
Characteristics [edit]
Collagen is one of the long, fibrous structural proteins whose functions are quite different from those of globular proteinssuch as enzymes. Tough bundles of collagen called collagen fibers are a major component of the extracellular matrix that supports most tissues and gives cells structure from the outside, but collagen is also found inside certain cells. Collagen has great tensile strength, and is the main component of fasciacartilageligamentstendonsbone and skin.[45][46] Along with soft keratin, it is responsible for skin strength and elasticity, and its degradation leads to wrinkles that accompanyaging.[47][48] It strengthens blood vessels and plays a role in tissue development. It is present in the cornea and lens of the eye in crystalline form.


Some Uses of Collagen in our World

Collagen has a wide variety of applications, from food to medical. For instance, it is used in cosmetic surgery and burns surgery. It is widely used in the form of collagen casings for sausages.

If collagen is sufficiently denatured, e.g. by heating, the three tropocollagen strands separate partially or completely into globular domains, containing a different secondary structure to the normal collagen polyproline II (PPII), e.g. random coils. This process describes the formation of gelatin, which is used in many foods, including flavored gelatin desserts. Besides food, gelatin has been used in pharmaceutical, cosmetic, and photography industries.[49] From a nutritional point of view, collagen and gelatin are a poor-quality sole source of protein since they do not contain all the essential amino acids in the proportions that the human body requires—they are not 'complete proteins' (as defined by food science, not that they are partially structured). Manufacturers of collagen-based dietary supplements claim that their products can improve skin and fingernail quality as well as joint health. However, mainstream scientific research has not shown strong evidence to support these claims.[citation needed] Individuals with problems in these areas are more likely to be suffering from some other underlying condition (such as normal aging, dry skin, arthritis etc.) rather than just a protein deficiency.

From the Greek for glue, kolla, the word collagen means "glue producer" and refers to the early process of boiling the skin and sinews of horses and other animals to obtain glue. Collagen adhesive was used by Egyptians about 4,000 years ago, and Native Americans used it in bows about 1,500 years ago. The oldest glue in the world, carbon-dated as more than 8,000 years old, was found to be collagen—used as a protective lining on rope baskets and embroidered fabrics, and to hold utensils together; also in crisscross decorations on human skulls.[50] Collagen normally converts to gelatin, but survived due to the dry conditions. Animal glues are thermoplastic, softening again upon reheating, and so they are still used in making musical instruments such as fine violins and guitars, which may have to be reopened for repairs—an application incompatible with tough, synthetic plastic adhesives, which are permanent. Animal sinews and skins, including leather, have been used to make useful articles for millennia.

Cardiac applications

The four dense collagen valve rings, the central body of the heart and the extended cardiac skeleton of the heart are histologically bound to the muscular myocardium. Collagen contribution to heart performance summarily represents an essential, unique and moving solid anchor opposed to the fluid mechanics of blood movement within the heart. The collagenous structure is an impermeable firewall that excludes both blood and electrical influence (through customary anatomical channels) from the upper {atrial} to the lower [ventricular] chambers of the heart. As proof, one could posit thatatrial fibrillation almost never deteriorates to ventricular fibrillation. Individual valvular leaflets are held in sail shape by collagen under variable pressureCalcium deposition within collagen occurs as a natural consequence of aging. Calcium rich fixed points in an otherwise moving display of blood and muscle enable current cardiac imaging technology to arrive at ratios essentially stating blood in cardiac input and blood out cardiac output. Specified imaging such as calcium scoringillustrates the utility of this methodology, especially in an aging patient subject to pathology of the collagen underpinning.
Type II collagen and rheumatoid arthritis 
According to a study[52] published in the journal Science, oral administration of type II collagen improves symptoms ofrheumatoid arthritis. The authors conducted a randomized, double-blind trial involving 60 patients with severe, active rheumatoid arthritis. A decrease in the number of swollen joints and tender joints occurred in subjects fed with chicken type II collagen for 3 months, but not in those that received a placebo. Four patients in the collagen group had complete remission of the disease. No side effects were evident.
Hydrolyzed type II collagen and osteoarthritis 
A published study[53] reports that ingestion of a novel low molecular weight hydrolyzed chicken sternal cartilage extract, containing a matrix of hydrolyzed type II collagenchondroitin sulfate, and hyaluronic acid, marketed under the brand nameBioCell Collagen, relieves joint discomfort associated with osteoarthritis. A randomized controlled trial (RCT) enrolling 80 subjects demonstrated that BioCell Collagen was well tolerated with no serious adverse event and led to a significant improvement in joint mobility compared to the placebo group on days 35 (p = 0.007) and 70 (p < 0.001).
Cosmetic surgery 
Collagen has been widely used in cosmetic surgery, as a healing aid for burn patients for reconstruction of bone and a wide variety of dental, orthopedic and surgical purposes. Both human and bovine collagen is widely used as dermal fillers for treatment of wrinkles and skin aging.[48] Some points of interest are:
1.  when used cosmetically, there is a chance of allergic reactions causing prolonged redness; however, this can be virtually eliminated by simple and inconspicuous patch testing prior to cosmetic use, and
2.  most medical collagen is derived from young beef cattle (bovine) from certified BSE-free animals. Most manufacturers use donor animals from either "closed herds", or from countries which have never had a reported case of BSE such as Australia, Brazil and New Zealand.
3.  porcine (pig) tissue is also widely used for producing collagen sheet for a variety of surgical purposes.
4.  alternatives using the patient's own fathyaluronic acid or polyacrylamide gels which are readily available.
Bone grafts 
As the skeleton forms the structure of the body, it is vital that it maintains its strength, even after breaks and injuries. Collagen is used in bone grafting as it has a triple helical structure, making it a very strong molecule. It is ideal for use in bones, as it does not compromise the structural integrity of the skeleton. The triple helical structure of collagen prevents it from being broken down by enzymes, it enables adhesiveness of cells and it is important for the proper assembly of the extracellular matrix.[54]
Tissue regeneration 
Collagen scaffolds are used in tissue regeneration, either in sponges, thin sheets or gels. Collagen has the correct properties for tissue regeneration such as pore structure, permeability, hydrophilicity and it is stable in vivo. Collagen scaffolds are also ideal for the deposition of cells, such as osteoblasts and fibroblasts and once inserted, growth is able to continue as normal in the tissue.[55]
Reconstructive surgical uses 
Collagens are widely employed in the construction of artificial skin substitutes used in the management of severe burns. These collagens may be derived from bovine, equine or porcine, and even human sources and are sometimes used in combination with siliconesglycosaminoglycansfibroblastsgrowth factors and other substances.
Collagen is also sold as a pill commercially as a joint mobility supplement with poor references. Because proteins are broken down into amino acids before absorption, there is no reason for orally ingested collagen to affect connective tissue in the body, except through the effect of individual amino acid supplementation.
Collagen is also frequently used in scientific research applications for cell culture, studying cell behavior and cellular interactions with the extracellular environment.[56]
Wound care management uses
Collagen is one of the body’s key natural resources and a component of skin tissue that can benefit all stages of the wound healing process. When collagen is made available to the wound bed, closure can occur. Wound deterioration, followed sometimes by procedures such as amputation, can thus be avoided.
Collagen is a natural product, therefore it is used as a natural wound dressing and has properties that artificial wound dressings do not have. It is resistant against bacteria, which is of vital importance in a wound dressing. It helps to keep the wound sterile, because of its natural ability to fight infection. When collagen is used as a burn dressing, healthygranulation tissue is able to form very quickly over the burn, helping it to heal rapidly.[57]
Throughout the 4 phases of wound healing, collagen performs the following functions in wound healing:
·        Guiding function: Collagen fibers serve to guide fibroblasts. Fibroblasts migrate along a connective tissue matrix.
·        Chemotactic properties: The large surface area available on collagen fibers can attract fibrogenic cells which help in healing.
·        Nucleation: Collagen, in the presence of certain neutral salt molecules can act as a nucleating agent causing formation of fibrillar structures. A collagen wound dressing might serve as a guide for orienting new collagen deposition and capillary growth.
·        Hemostatic properties: Blood platelets interact with the collagen to make a hemostatic plug.


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2 comments:

  1. This article is fabulous.. Your way presenting the article is completely differ from others, Information about the types collagen and the use of that collagen products is nice.

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  2. Thanks so much. You have encouraged me to get busy and post more things!

    ReplyDelete