Printing with Collagen
- Bioprinting Organotypic Hydrogels with Improved Mesenchymal Stem Cell Remodeling and Mineralization Properties for Bone Tissue Engineering,
Daniela Filipa Duarte Campos, Andreas Blaeser, Kate Buellesbach, Kshama Shree Sen, Weiwei Xun, Walter Tillmann, Horst Fischer,
Adv. Healthcare Mater. 2016.
Collagen injections can be used in cosmetic procedures to improve the contours of aging skin.
Types of collagen
- Fibrillar (Type I, II, III, V, XI)
- FACIT (Fibril Associated Collagens with Interrupted Triple Helices) (Type IX, XII, XIV, XVI, XIX)
- Short chain (Type VIII, X)
- Basement membrane (Type IV)
- Multiplexin (Multiple Triple Helix domains with Interruptions) (Type XV, XVIII)
- MACIT (Membrane Associated Collagens with Interrupted Triple Helices) (Type XIII, XVII)
- Other (Type VI, VII)
- Type I: skin, tendon, vascular ligature, organs, bone (main component of the organic part of bone)
- Type II: cartilage (main collagenous component of cartilage)
- Type III: reticulate (main component of reticular fibers), commonly found alongside type I.
- Type IV: forms basal lamina, the epithelium-secreted layer of the basement membrane.
- Type V: cell surfaces, hair and placenta
Tobacco contains chemicals that damage collagen
Hydrolyzed type II collagen and osteoarthritis
- Protein makes up around 20% of the body's mass, and collagen makes up around 30% of the protein in the human body.
- There are at least 16 types of collagen, but 80-90% of the collagen in the body consists of types I, II, and III.
- Type I collagen fibrils are stronger than steel (gram for gram).
- Collagen is most commonly found within the body in the skin, bones and connective tissues.
- The word "collagen" is derived from the Greek "kolla," meaning glue.
- Collagen gives the skin its strength and structure, and also plays a role in the replacement of dead skin cells.
- Collagen production declines with age (as part of intrinsic aging), and is reduced by exposure to ultraviolet light and other environmental factors (extrinsic aging).
- Collagen in medical products can be derived from human, bovine, porcine and ovine sources.
- Collagen dressings attract new skin cells to wound sites.
- Cosmetic products such as revitalizing lotions that claim to increase collagen levels are unlikely to do so, as collagen molecules are too large to be absorbed through the skin.
- Collagen production can be stimulated through the use of laser therapy and the use of all-trans retinoic acid (a form ofvitamin A).
- Controllable factors that damage the production of collagen include sunlight, smoking and high sugar consumption.
- 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.
- 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.
Reconstructive surgical uses
- 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.
|Amino acid||Abundance in mammal skin|
|Abundance in fish skin|
- Transcription of mRNA: About 34 genes are associated with collagen formation, each coding for a specific mRNA sequence, and typically have the "COL" prefix. The beginning of collagen synthesis begins with turning on genes which are associated with the formation of a particular alpha peptide (typically alpha 1, 2 or 3).
- Pre-pro-peptide formation: Once the final mRNA exits from the cell nucleus and enters into the cytoplasm, it links with the ribosomal subunits and the process of translation occurs. The early/first part of the new peptide is known as the signal sequence. The signal sequence on the N-terminal of the peptide is recognized by a signal recognition particle on the endoplasmic reticulum, which will be responsible for directing the pre-pro-peptide into the endoplasmic reticulum. Therefore, once the synthesis of new peptide is finished, it goes directly into the endoplasmic reticulum for post-translational processing. It is now known as pre-pro-collagen.
- Pre-pro-peptide to pro-collagen: Three modifications of the pre-pro-peptide occur leading to the formation of the alpha peptide:
- The signal peptide on the N-terminal is dissolved, and the molecule is now known as propeptide (not procollagen).
- Hydroxylation of lysines and prolines on propeptide by the enzymes 'prolyl hydroxylase' and 'lysyl hydroxylase' (to produce hydroxyproline and hydroxylysine) occurs to aid cross-linking of the alpha peptides. This enzymatic step requires vitamin C as a cofactor. In scurvy, the lack of hydroxylation of prolines and lysines causes a looser triple helix (which is formed by three alpha peptides).
- Glycosylation occurs by adding either glucose or galactose monomers onto the hydroxyl groups that were placed onto lysines, but not on prolines.
- Once these modifications have taken place, three of the hydroxylated and glycosylated propeptides twist into a triple helix forming procollagen. Procollagen still has unwound ends, which will be later trimmed. At this point, the procollagen is packaged into a transfer vesicle destined for the Golgi apparatus.
- Golgi apparatus modification: In the Golgi apparatus, the procollagen goes through one last post-translational modification before being secreted out of the cell. In this step, oligosaccharides (not monosaccharides as in step 3) are added, and then the procollagen is packaged into a secretory vesicle destined for the extracellular space.
- Formation of tropocollagen: Once outside the cell, membrane bound enzymes known as 'collagen peptidases', remove the "loose ends" of the procollagen molecule. What is left is known as tropocollagen. Defects in this step produce one of the many collagenopathies known as Ehlers-Danlos syndrome. This step is absent when synthesizing type III, a type of fibrilar collagen.
- Formation of the collagen fibril: 'Lysyl oxidase', an extracellular enzyme, produces the final step in the collagen synthesis pathway. This enzyme acts on lysines and hydroxylysines producing aldehyde groups, which will eventually undergo covalent bonding between tropocollagen molecules. This polymer of tropocollogen is known as a collagen fibril.
- Glycine is found at almost every third residue.
- Proline makes up about 17% of collagen.
- Collagen contains two uncommon derivative amino acids not directly inserted during translation. These amino acids are found at specific locations relative to glycine and are modified post-translationally by different enzymes, both of which require vitamin C as acofactor.
Collagen I formation
- Inside the cell
- Two types of alpha chains are formed during translation on ribosomes along the rough endoplasmic reticulum (RER): alpha-1 and alpha-2 chains. These peptide chains (known as preprocollagen) have registration peptides on each end and a signal peptide.
- Polypeptide chains are released into the lumen of the RER.
- Signal peptides are cleaved inside the RER and the chains are now known as pro-alpha chains.
- Hydroxylation of lysine and proline amino acids occurs inside the lumen. This process is dependent on ascorbic acid (vitamin C) as a cofactor.
- Glycosylation of specific hydroxylysine residues occurs.
- Triple alpha helical structure is formed inside the endoplasmic reticulum from two alpha-1 chains and one alpha-2 chain.
- Procollagen is shipped to the Golgi apparatus, where it is packaged and secreted by exocytosis.
- Outside the cell
- Registration peptides are cleaved and tropocollagen is formed by procollagen peptidase.
- Multiple tropocollagen molecules form collagen fibrils, via covalent cross-linking (aldol reaction) by lysyl oxidase which links hydroxylysine and lysine residues. Multiple collagen fibrils form into collagen fibers.
- Collagen may be attached to cell membranes via several types of protein, including fibronectin and integrin.
|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 endomysiumsurrounding muscle fibers, fibrocartilage, and the organic part of bones and teeth.||COL1A1, COL1A2||Osteogenesis imperfecta, Ehlers–Danlos syndrome, Infantile cortical hyperostosis a.k.a. Caffey's disease|
|II||Hyaline cartilage, makes up 50% of all cartilage protein. Vitreous humour of the eye.||COL2A1||Collagenopathy, types II and XI|
|III||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||COL3A1||Ehlers–Danlos syndrome, Dupuytren's contracture|
|IV||Basal lamina; eye lens. Also serves as part of the filtration system in capillaries and the glomeruli ofnephron in the kidney.||COL4A1, COL4A2,COL4A3,COL4A4,COL4A5,COL4A6||Alport syndrome, Goodpasture's syndrome|
|V||Most interstitial tissue, assoc. with type I, associated with placenta||COL5A1, COL5A2,COL5A3||Ehlers–Danlos syndrome (Classical)|
|VI||Most interstitial tissue, assoc. with type I||COL6A1, COL6A2,COL6A3,COL6A5||Ulrich myopathy, Bethlem myopathy,Atopic dermatitis|
|VII||Forms anchoring fibrils in dermoepidermal junctions||COL7A1||Epidermolysis bullosa dystrophica|
|VIII||Some endothelial cells||COL8A1, COL8A2||Posterior polymorphous corneal dystrophy 2|
|IX||FACIT collagen, cartilage, assoc. with type II and XI fibrils||COL9A1, COL9A2,COL9A3||EDM2 and EDM3|
|X||Hypertrophic and mineralizing cartilage||COL10A1||Schmid metaphyseal dysplasia|
|XI||Cartilage||COL11A1, COL11A2||Collagenopathy, types II and XI|
|XII||FACIT collagen, interacts with type I containing fibrils, decorin and glycosaminoglycans||COL12A1||–|
|XIII||Transmembrane collagen, interacts with integrin a1b1, fibronectin and components of basement membranes like nidogen and perlecan.||COL13A1||–|
|XIV||FACIT collagen, also known as undulin||COL14A1||–|
|XVII||Transmembrane collagen, also known as BP180, a 180 kDa protein||COL17A1||Bullous pemphigoid and certain forms of junctional epidermolysis bullosa|
|XVIII||Source of endostatin||COL18A1||–|
- Hydrolyzed collagen, a common form in which collagen is sold as a supplement.
- Animal glue
- Fibrous protein
- Osteoid, collagen containing component of bone
- Lysyl oxidase and LOXL1, LOXL2, LOXL3, LOXL4 in collagen formation
- Collagenase, the enzyme involved in collagen breakdown and remodelling. For more on other proteases that target collagen see The Proteolysis Map
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- Database of type I and type III collagen mutations
- Science.dirbix Collagen
- Collagen Stability Calculator
- Computer-generated animations of the assembly of Type I and Type IV Collagens
- Integrin-Collagen interface, PMAP (The Proteolysis Map)—animation
- Integrin-Collagen binding model, PMAP (The Proteolysis Map)—animation
- Collagen-Integrin atomic detail, PMAP (The Proteolysis Map)—animation
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