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Collagen: A Brief Analysis
Oral and Maxillofacial Pathology Journal, January-June 2019;10(1):11-17 11
OMPJ
Collagen: A Brief Analysis
1Supriya Sharma, 2Sanjay Dwivedi, 3Shaleen Chandra, 4Akansha Srivastava, 5Pradkshana Vijay
OMPJ
REVIEW ARTICLE
10.5005/jp-journals-10037-1143
ABSTRACT
Collagen is the most abounding structural protein in a human
body representing 30% of its dry weight and is significant to
health because it designates the structure of skin, connective
tissues, bones, tendons, and cartilage. Much advancement
has been made in demonstrating the structure of collagen triple
helices and the physicochemical premise for their stability.
Collagen is the protein molecule which produces the major part
of the extracellular matrix. Artificial collagen fibrils that exhibit
some characteristics of natural collagen fibrils are now con-
gregated using chemical synthesis and self-aggregation. The
indigenous collagen fibrils lead further development of artificial
collagenous materials for nanotechnology and biomedicine.
Keywords: Collagen, Structure of Collagen, Diagnostic Impor-
tance, Collagen Disorders.
How to cite this article: Sharma S, Dwivedi S, Chandra S,
Srivastava A, Vijay P. Collagen: A Brief Analysis. Oral Maxillofac
Pathol J 2019;10(1):11-17.
Source of support: Nil
Conflict of interest: None
INTRODUCTION
Collagen is the unique, triple helical protein molecule
which organizes the major part of the extracellular matrix.1
The word collagen was procured from the Greek word
“kolla” which estates “glue producer”. Previously the col-
lagen of tendons and bones was accustomed in the industry
to manufacture glue. Also in organism collagen is a kind
of glue.2 Collagen is a kind of biological macromolecule
which constructs a greatly organized, three-dimensional
architecture and can transfer any component due to its
network-like organizational nature. It is used as a biomate-
rial because of its extensive applicability in diverse fields.
Its adaptable role is due to its immense properties such as
biocompatibility, biodegradability and easy availability.1
They are centrally involved in the constructions of
basement membranes along with diverse structures of the
extracellular matrix, fibrillar and microfibrillar networks
of the extracellular matrix. It establishes their fundamental
fractional monetary unit and identifies crucial steps in
the biosynthesis and supramolecular preparing of fibril-
lar collagens.3 They are the most abundant structural
component of the connective tissue and are present in all
multicellular organisms. In the light microscope, collagen
fibers typically appear as the wavy structure of variable
width and intermediate length.
They stain readily with eosin and other acidic dyes.
When examined with a transmission electron micro-
scope (TEM), collagen fibers appear as bundles of
fine thread-like subunits. These subunits are collagen
fibrils. Within individual fibers, the collagen fibrils are
relatively uniform in diameter. In different locations
and at different stages of development, however, the
fibrils differ in size. In developing or immature tissues,
the fibrils may be as small as 15 or 20 nm in diameter.
In dense regular connective tissue of tendons or other
tissues that are subject to considerable stress, they may
measure up to 300 nm in diameter. Collagens are also
known to form highly ordered aggregates. The perio-
dicity in these macromolecular structures makes them
suitable for investigation by means of X-ray diffraction.4-6
However, collagen attracts attention not only for com-
mercial motives. Also from a clinical perspective, there
is much mesmerized in collagens because many diverse
diseases are concomitant to disarray in collagen. Genetic
disorders of collagen metabolism customarily influence
tissues in which the proper advancement and integrity of
connective tissue are of preponderant importance. Thus,
a better understanding of the spatial structure will give
us more insight into collagen-related disorder diseases.1,7
Structure and Types of Collagen
It consists of 3 helically coiled linear chains, each of about
1,000 amino acids. Two of these chains (α1) are identical
while the third (α2) has a different amino acid composi-
tion. The amino acid composition of collagen is:
25% Glycine
25% Proline
Hydroxyproline
1,5Senior Resident, 2Research Scientist, 3Professor and Head,
4Senior Dentist
1,3,5Department of Oral Pathology and Microbiology, Faculty of
Dental Sciences, King George’s Medical University, Lucknow,
Uttar Pradesh, India
2Department of Plant Ecology and Climate Division CSIR-
National Botanical Research Institute, Lucknow, Uttar Pradesh,
India
4JRMA Health Care, Navi Mumbai, India
Corresponding Author: Dr. Supriya Sharma, Department of
Oral Pathology and Microbiology, Faculty of Dental Sciences,
King George’s Medical University, Lucknow, Uttar Pradesh, India.
Phone: +919452274428, e-mail: supriyasharma0709@gmail.com
Supriya Sharma et al.
12
In α chain glycine is repeated every fourth residue.
The triplets gly-pro-pro and gly-pro-hpro occur frequently.
A protein consists of one or more polypeptide chains.
Collagen consists of 3 polypeptide chains, each in the form
of a left-handed helix. The explaining feature of collagen is
a distinguished constructional motif in which three parallel
polypeptide strands in a left-handed, polyproline type II
helical conformation coil about each other with a one-residue
stagger to organize a right-handed triple helix (Fig. 1).3,4,6,8
Until now, the molecule has been classified in 28 dif-
ferent types that are grouped into eight families depend-
ing on its structure, chain bonding, and position in the
human body (Table 1).4 Among the classifications, it can
be found the fibril-forming, microfibrillar, anchoring
fibrils, hexagonal network-forming, basement membrane,
fibril-associated collagens with interrupted triple helix
(FACIT), transmembrane, and multiplexins.
Microscopic Appearance
Collagen fibers of connective tissue are generally less than
10 μm in diameter and are colorless, when unstained. They
appear as long, wavy, pink fibers bundles after staining
with Hematoxylin and Eosin. These fibers are constructed
from parallel aggregates of thinner fibrils 10 to 300 nm in
diameter and numerous micrometers in length.4
In electron micrographs of negatively stained prepa-
rations, densely stained molecule fills the gap region, or
holes between the ends of the adjacent collagen molecules
and heavy metals display cross banding at regular inter-
vals of 67 nm, a characteristic property of these fibers
is seen. In hard tissues (bone, dentin, cementum), these
holes are filled with mineral crystals. The banding pattern
of the fibrils seen in thinly sectioned electron micrograph
results from the differing amount of stain bound by a
charged amino acid that is aligned in adjacent collagen
molecules.9,10
Fig. 1: Collagen Triple-helix Structure3
Mechanism of collagen Formation and
Degradation
Collagen Formation
The cells of the mesenchyme and their derivatives
(fibroblasts, odontoblast, osteoblast, cementoblasts, and
chondroblasts) are the active producers of collagen. Alterna-
tive cell types forming collagen are epithelial, endothelial,
Schwann and muscle cells. As an excretory protein, fibrous
collagen is manufactured as a proprotein (procollagen).
Messenger RNA controls the assembly of distinct amino
acids into polypeptide chains on ribosome related with the
rough endoplasmic reticulum (RER). The primary poly-
peptide chains are around one and a half times lengthened
than those in the consequent collagen molecule because they
have N- and C-terminal distensions that are imperative for
the aggregation of the triple helical molecule. As the chains
are incorporated, they are transferred into the lumen of the
rough endoplasmic reticulum, where considerable post-
translational modification takes place.
The first conversion is innumerable hydroxylation of
many of the lysine and proline by-products in the chain,
which allows hydrogen bonding with the alongside
chains as the triple helix is manufactured. The vitamin C
reliant enzymes lysyl hydroxylase and prolyl hydroxylase
are essential for this step. Through the effect of galactos-
yltransferase in the rough endoplasmic reticulum, some
of the hydroxylysine remnants are glycosylated by the
inclusion of galactose.
The three polypeptide chains are assembled into
the triple helix. Proper alignment of the chains then is
achieved by disulfide bonding at the C-terminal extension
and then the three chains twist around themselves to “zip
up” the helix. The assembled helix then is transported to
the Golgi complex, where glycosylation is completed by
the addition of glucose to the O-linked galactose residues.
Secretary granules containing the procollagen molecule
are formed at the Trans face of the Golgi complex and
are released subsequently by the exocytosis by the cell
surface. The formation and secretion of the collagen mol-
ecule take approximately 35 to 60 minutes.4,9,10
Fibroblast
It is the most common cell of connective tissue that
forms and retains the extracellular matrix. They give a
structural framework for numerous tissues and play an
imperative role in wound healing. The essential func-
tion of fibroblasts is to preserve the structural integrity
of connective tissues by repeatedly secreting precursors
of the extracellular matrix, primarily the ground sub-
stance and diversity of fibers. They are identified by their
interrelation with collagen fibers bundles. The quiescent
Collagen: A Brief Analysis
Oral and Maxillofacial Pathology Journal, January-June 2019;10(1):11-17 13
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Table 1: Types of collagen4
Molecule type Synthesizing cell Function Location in body
1. Fibril-forming: most common of all
collagens
Fibroblasts, Osteoblasts,
Odontoblasts, Cemento blasts
Resists tension Dermis, tendon,
Ligaments, capsules of
organs, bone, dentin,
Cementum
2. Fibril-forming Chondroblasts Resists pressure Hyaline and elastic
cartilage
3. Fibril-forming; also known as
reticular bers. Highly glycosylated
Fibroblasts, reticular cells,
smooth muscle cells, hepato-
cytes
Forms structural
framework of spleen, Liver,
lymph nodes. smooth
muscle, adipose tissue
The lymphatic
system, spleen, liver,
cardiovascular system,
Lung. skin
4. Network-forming: do not display
67 nm periodicity and a -chains
retain propeptides
Epithelial cells, muscle
Cells, Schwann cells
Forms meshwork of the
lamina densa of the basal
lamina to provide support
and ltration
Basal lamina
5. Fibril-forming Fibroblasts, mesenchyme
cells
Associated with type
I collagen, also with
placental ground
substance
Dermis, tendon,
ligaments, capsules of
organs, bone, Cementum,
placenta
6. Microbre forming collagen _ Bridging between cells
and matrix (has binding
properties for cells,
proteoglycan, a type I
collagen)
Ligaments, skin, cartilage
7. Network-forming: form dimers that
assemble into anchoring brils
Epidermal cells Forms anchoring brils
that fasten lamina densa
to underlying lamina
reticularis
Junction of epidermis and
dermis
8. Meshwork _ Tissue support. porous
meshwork, provide
compressive strength
Basal laminae of
endothelial cells and
smooth muscle cells and
Descemet’s membrane of
the cornea
9. Fibril-associated: decorate the
surface of type II collagen bers
Epithelial cells Associates with type II
Collagen bers
Cartilage
10. Meshwork _ Calcium binding Hypertrophic zone of
cartilage growth plate
11. Fibril collagen bers _Forms core of type II bers
provides tensile strength
Cartilage and vitreous
humor
12. Fibril-associated; decorate the
surface of type I collagen bers
Fibroblasts Associated with type I
collagen
bers
Tendons. ligaments and
aponeuroses
13. Transmembrane protein Cell-matrix and cell,
adhesion
Cell surfaces, focal
adhesion, and
intercalated disks
14. FACIT _ Modulates bril
interactions
15. Endostatin forming collagen Endothelial cells Proteolytic release of
antiangiogenic factor
Endothelial basement
membrane
16. Cartilage and placenta _ Unknown Endothelial, perineural
muscle and some
epithelial basement
membrane, cartilage, and
placenta
17. Collagen-like protein: a
transmembrane protein, formerly
known as bullouspemphigoid
antigen
Epithelial cells Cell to matrix attachment Hemidesmosomes
18. Collagen-like protein; cleavage of
its C – terminal forms endostatin
and
Endothelial cells Proteolytic release of
antiangiogenic factor
Endothelial basement
membrane
Contd...
Supriya Sharma et al.
14
Molecule type Synthesizing cell Function Location in body
19. FACIT _ Unknown Endothelial, perineural
muscle and some
epithelial basement
membrane, cartilage, and
placenta
20. FACIT Cornea (chick)
21. FACIT - - Stomach, kidney
22. FACIT - - Tissue junctions
23. Membrane-associated collagen
with interrupted triple helix
- - Heart, retina
24. Fibrillar - - Bones, cornea
25. Membrane-associated collagen
with interrupted triple helix
- - Brain, heart, testis
26. FACIT - - Testis, ovary
27. Fibrillar - - Cartilage
28. Microber forming collagen - - Dermis, sciatic nerve
fibroblast or fibrocyte is minor than the active fibroblast
and is commonly spindle-shaped. It has a minor, darker,
elongated nucleus; fewer processes and higher acido-
philic cytoplasm with the much less rough endoplasmic
reticulum. They have a branched cytoplasm surrounding
an elliptical, speckled nucleus having one or two nucleoli.
Active fibroblasts can be identified by their oval, pale-
staining nucleus and higher amount of cytoplasm, Golgi
apparatus, abundant rough endoplasmic reticulum,
secretory vesicles and mitochondria (Fig. 2). They exhibit
motility and contractility which are crucial during connec-
tive tissue remodeling and generation and wound repair.
In certain tissues, fibroblasts have significant contractile
properties and are called as Myofibroblasts.4
Degradation of Collagen
The C-terminal extensions and at least part of the N-ter-
minal extensions are removed by the action of procol-
lagen peptidases. These condensed molecules range as
a 5 unit, quarter-overwhelmed microfibrils, which then
aggregate in a collateral function, giving advancement
to a well-organized series of holes or gaps inside the
fibrils. These gaps are the regions of the primary depos-
its of mineral-related with the collagen fibrils in dentin,
bones, and cementum. After the fibrils are assembled, the
remaining portion of the N-terminal extension is removed
by procollagen peptidase. The oxidization of some lysine
and hydroxylysine residues by the extracellular enzyme
lysyl oxidase, forming reactive aldehydes, results in inter-
molecular cross-links that further stabilize the fibrils. 4,9,10
Factors involved in collagen degradation are:
Highly strong to Proteolytic attack
Collagenase 1, 2 and 3 degenerate types I, II, III, V collagen
Collagenase 3 can degenerate type I, II, III, IV, IX,
Fig. 2: Shape of fibroblast: A: Nucleus; B: Nucleolus; C: Golgi appara-
tus; D: Cytoplasm; E: Intermediate/transfer vesicles; F: Ribosomes; G:
Mitochondria; H: Polyribosome; I: Rough endoplasmic reticulum; J: Col-
lagen fibrils; K: Cell processes; L: Microtubules; M: Secretory granules.4
X, XI, fibronectin and another extracellular matrix
component.11
Matrix metalloproteinases (MMP) is a great family of
proteolytic enzymes that involves:
Collagenases (MMP-1, 8, 13)
Metalloelastases (MMP-12)
Stromelysins (MMP-3, 10, 11)
Matrilysin (MMP-7)
Gelatinases (MMP-2, 9) 4
Diagnostic Importance of Collagen in Various
Conditions
Many histochemical stains have been accustomed to
determine Collagen fibers which involve Weigert’s
Resorcin Fuchsin, Modified Movat’s Stain, Goldner’s
Trichrome method, Van Gieson, Masson’s Trichrome, etc,
but the picrosirius red stain underneath the polarizing
microscope is the most extensively used because of the
inherent character of birefringence of collagen.11
Cysts
Collagen was considered playing an active role in the patho-
logic process and expansion of odontogenic cyst. Junqueira
Contd...
Collagen: A Brief Analysis
Oral and Maxillofacial Pathology Journal, January-June 2019;10(1):11-17 15
OMPJ
et al. reported that under pathological conditions birefrin-
gence represents various patterns in contrast with collagen
in general tissue and demonstrated that type I collagen
was massive, greatly birefringent red fibers while type III
collagen exposed as fine weakly birefringent green fibers.12
Tumor
In a tumor, there is an enhanced density of collagen in
the initial phase, which stimulates tumor initiation and
metastasis.13
Odontogenic Fibroma
In odontogenic fibromas, mature type I collagen fibers
are present. These fibers ran roughly parallel to the inac-
tive epithelial strands and foci of mineralization were
surrounded by concentric thick type I collagen bundles.12
Ameloblastoma
The collagen fibers in the basement membranes of amelo-
blasts in ameloblastomas are found to be spatially orga-
nized with thick type I collagen passing perpendicularly
through the basement membrane zone and merging with
the collagen in the capsule and fibrous septa between the
epithelial follicles.12
Oral Submucous Fibrosis
One of the most customary precancerous conditions
which are broadly pervasive in the Indian subcontinent is
oral submucous fibrosis (OSMF). In a very early stage, fine
fibrillar collagen distributed with pronounced edema and
sturdy fibroblastic response demonstrating plump young
fibroblasts including profuse cytoplasm will be observed.
In early and moderately advanced stage collagen is seen
as thickened separate bundles and moderately hyalinised
respectively.14 Studies done in OSMF using picrosirius red
stain and polarizing microscopy revealed that there was a
gradual decrease in the greenish-yellow color of the fibers
and a shift to orange-red color with increase in severity
of the disease which appeared that the tight packing of
collagen fibers in OSMF progressively increased as the
disease progressed from early to advanced stages.11
In Drug Delivery Systems and Tissue Engineering
Collagen is a predominant biomaterial in medical uti-
lization due to its particular characteristics, like weak
antigenicity and biodegradability. In the biomedical
application, the chief reason for the usefulness of collagen
is the fabrication of fibers with supplemental vitality and
stability through its self-assembly and cross-linking and
the in vivo metabolism of collagen is supervised by the
application of cross-linking agents, such as glutaralde-
hyde, formaldehyde, polyepoxy compounds, chromium
tanning, acrylamide, and carbodiimides.15
A generalized view of collagen in the body
Collagens are a great family of triple helical proteins that
are extensive throughout the body. They are crucial for a
wide range of functions, involving cell migration, cancer,
angiogenesis, tissue morphogenesis, tissue scaffolding,
cell adhesion, and tissue repair. It is the main component
of tissues such as fibrous tissue, bone, cartilage, valves of
heart, cornea, and basement membrane etc.1,4,6,16
Collagen in Health
Collagen is seldom referred to as the body’s cement that
keeps everything in place. It is crucial to health because
it dictates the designs of skin, connective tissues, tendon,
bone, and cartilage.16
Skin Health
Collagen plays an important role in skin health. Dermis
layer of the skin is a connective tissue layer made up of
dense and stout collagen fibers, fibroblast, and histio-
cytes. Collagen type I constitute 70% of the collagen in
the skin, with type III being 10% and a trace amount of
collagen types IV, V, VI and VIII. Collagen conserves the
toughness and elasticity of the skin. Collagen in the form
of collagen hydrolysate keep skin hydrated. During the
aging process, a lack of collagen becomes obvious as skin
begins to sag and lines and wrinkles begin to form. In the
development of scar tissue as a result of age or injury,
there is variation in the abundance of types I and III col-
lagen as well as their proportion to one another. Type III
collagen synthesis reduces with age resulting in changes
in skin tension, elasticity, and healing.4
Muscles
In muscle tissue, it serves as an utmost component of
endomysium. In Smooth Muscle Cells (SMCs) collagen
exist as a meshwork surrounding individual SMCs (type
IV or basement membrane collagen) or as interstitial
dense fibers that occupy a substantial volume of the tissue
(type I and III fibrillar collagens).17,18,19
Wound Healing
Collagen plays an important role in wound healing by
repair and formation of a scar. The tensile strength of the
wound increases by its deposition and remodeling, which
is nearly 20% of normal by 3 weeks after injury and gradu-
ally reaches an extreme of 70% of that of normal skin. Col-
Supriya Sharma et al.
16
lagen overproduction can produce an abnormal scar, which
delays wound healing. A chronic wound burden between
the elderly has been recorded and much of this age-related
delayed wound healing is caused by diminished collagen
synthesis and an advanced degradation. Increase in col-
lagen and fibroblasts during healing proposed that a cor-
relation might exist among a quantity of collagen, number
of fibroblasts and tensile strength of a scar.4,16
Bone
Bone is a complex and dynamic tissue that renders
structural support for the body, preservation of internal
organs and acts as levers to which muscles are attached,
allowing movement. In total, out of 22 to 25% of the
organic component, the principal collagen type I is 94
to 98% along with other noncollagenous proteins and
2 to 5% are cells present in the bone tissue. The mixture
of flexible collagen and hard mineral makes bone dense
than cartilage without being brittle. A mixture of water
and collagen mesh constructs a strong and slippery pad
in the joint that shields the ends of the bones in the joint
during muscle movement.
Cartilage, Tendon, Ligaments
In fibrous tissue, such as tendon and ligament, collagen
in the form of elongated fibrils is predominantly present.
It is a stretchy and flexible protein that is used by the
body to support tissues and thus it plays an important
role in the preservation of the cartilage, tendons, and
ligaments. Normal tendon consists of soft and fibrous
connective tissue that is consisted of densely packed col-
lagen fibers bundles and surrounded by a tendon sheath
also consisting of components of the extracellular matrix.
Collagen comprises 75% of the dry tendon weight and
functions principally to withstand and transfer large
forces among muscle and bone. Collagen also constructs
a great constituent of cartilages. Cartilage collagen
fibrils composed of collagen II, the quantitatively few
collagens IX and XI.
Dental Tissues
Dentin
The mature dentin is made up of nearly 20% organic
material, 70% inorganic material and 10% water by
weight. The organic phase is about 30% collagen (prin-
cipally type I with few amounts of types III and V)
with fractional inclusions of non-collagenous matrix
proteins and lipids. Collagen type I serve as a scaffold
that contains a great proportion (estimated at 56%) of
the mineral in the pores and holes of fibrils.
Pulp
The extracellular compartment of the matrix or pulp made
up of collagen fibers and ground substance. The fibers
are mainly types I and III collagen. The general collagen
content of the pulp advances with age, the ratio among
types I and III remain steady and the increased amount
of extracellular collagen constructs into fiber bundles.
Cementum
Type I collagen (forms 90% of the organic matrix) is
predominant collagen present in cementum. Collagens
found in trace amount in cementum are types V, VI,
and XIV. Different collagens related with cementum
include type III, less cross-linked collagen found in high
concentrations during advancement and reconstruction
and repair of mineralized tissues and type XII that binds
to type I collagen and also to non-collagenous matrix
proteins.
Periodontal ligament
The periodontal ligament is made up of collagen fibers
bundles connecting cementum and alveolar bone proper.
The chief collagens are types I, III and XII, with individual
fibrils having an approximately minor average diameter
than tendon collagen fibrils.
Principal fibers are the vast majority of collagen fibrils
found in the periodontal ligament and are arranged in
definite and distinct fiber bundles. The periodontal liga-
ment has also the capability to adapt to functional changes.
When the functional demand advances, the thickness of
the periodontal ligament can advance by as much as 50 %
and the fiber bundles also increase noticeably in thickness.
Basement membrane:
The epithelial basement membrane and neighboring area
are termed the epithelial basement membrane zone. The
lamina densa comprising of type IV collagen that is covered
by heparin sulfate, a glycosaminoglycan and anchoring
fibrils, that are made up of type VII collagen and widen
from the lamina densa to the connective tissue.4
Collagen Disorders
These collagen disorders are classified as 20
Heritable/Genetic Collagen Disorders:
Ehlers-Danlos syndrome
Osteogenesis Imperfecta
Stickler Syndrome
Alport Syndrome
Collagen: A Brief Analysis
Oral and Maxillofacial Pathology Journal, January-June 2019;10(1):11-17 17
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Epidermolysis Bullosa
Marfan Syndrome
Collagen Vascular Disorders/Autoimmune Collagen
Disorders:
Systemic Lupus Erythematous
Systemic Sclerosis
Oral submucous fibrosis
Sjogren’s syndrome
Scleroderma
Rheumatoid Arthritis
Ankylosis Spondylitis
Miscellaneous:
Human Atherosclerotic Plaques
Osteoporosis
Scurvy
CONCLUSION
Collagen is the predominant structural material of the
body and is the most bountiful mammalian protein
accounting for about 20 to 30% of total body proteins.
They are principal constituent of the extracellular matrix
(ECM) that encourages the tissues. The ECM is defined
as the diverse collection of proteins and sugars that sur-
rounds cells in all solid tissues.
They have been classified by types that describe spe-
cific sets of polypeptide chains that can form homo- and
heterotrimeric assemblies. Collagen plays an impera-
tive role in the development of tissues and organs and
is involved in diverse functional expressions of cells. It
is a good surface-active agent and has the capability to
penetrate a lipid-free interface.4,5,6,21
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... Collagen is a structural protein, which is of upmost importance to vertebrates, as it contributes to one-third of their body mass [1,2]. It is responsible for mechanical stability and structural integrity of living organisms, and is prevalent in both mineralised (bone, teeth, fish scales) and nonmineralised (skin, tendon, ligament, cornea) tissues. ...
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Collagen is the basic protein of animal tissues and has a complex hierarchical structure. It plays a crucial role in maintaining the mechanical and structural stability of biological tissues. Over the years, it has become a material of interest in the biomedical industries thanks to its excellent biocompatibility and biodegradability and low antigenicity. Despite its significance, the mechanical properties and performance of pure collagen have been never reviewed. In this work, the emphasis is on the mechanics of collagen at different hierarchical levels and its long-term mechanical performance. In addition, the effect of hydration, important for various applications, was considered throughout the study because of its dramatic influence on the mechanics of collagen. Furthermore, the discrepancies in reports of the mechanical properties of collagenous tissues (basically composed of 20–30% collagen fibres) and those of pure collagen are discussed.
... Collagen is an essential component of the dermis and plays an essential role in wrinkling [145]. Type I and type III collagen are the most common types of collagen found in the extracellular matrix (ECM) and connective tissue [146]. Type IV collagen is found only in the basement membrane and, together with type VII collagen, plays a vital role in the adhesion of the skin epidermis [147]. ...
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Bouea macrophylla Griffith (B. macrophylla) is one of the many herbal plants found in Asia, and its fruit is plum mango. This plant is rich in secondary metabolites, including flavonoids, tannins, polyphenolic compounds, and many others. Due to its bioactive components, plum mango has powerful antioxidants that have therapeutic benefits for many common ailments, including cardiovascular disease, diabetes, and cancer. This review describes the evolution of plum mango’s phytochemical properties and pharmacological activities including in vitro and in vivo studies. The pharmacological activities of B. macrophylla Griffith reviewed in this article are antioxidant, anticancer, antihyperglycemic, antimicrobial, and antiphotoaging. Each of these pharmacological activities described and studied the possible cellular and molecular mechanisms of action. Interestingly, plum mango seeds show good pharmacological activity where the seed is the part of the plant that is a waste product. This can be an advantage because of its economic value as a herbal medicine. Overall, the findings described in this review aim to allow this plant to be explored and utilized more widely, especially as a new drug discovery.
... Collagen is the main structural protein in the muscle wall layer, accounting for 30% of the dry tissue weight [1]. Defects in collagenases will result in abnormal collagen synthesis or increased protease activity leading to pathological collagen degradation [2]. ...
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Introduction: A hernia is a protrusion of an organ or tissue through an abnormal anatomical channel or opening. Epidemiological data indicated an increased prevalence of inguinal hernias in patients with connective tissue diseases. The biomechanical strength of connective tissue is highly dependent on the constituent of the matrix, including collagen. Fibroblasts produce and secrete procollagen containing high concentrations of proline and lysine. Collagen integrity plays an essential role in preventing hernia formation in the abdominal wall. To investigate the relationship between collagen proline levels of the anterior rectus sheath tissue in patients with lateral inguinal hernias (indirect inguinal hernia). Methods: The study participants consisted of 67 inguinal hernia patients. A sample of anterior rectus tissue was obtained at the time of surgery, then being washed in a PBS buffer (pH 7.4). The measurement of collagen proline levels was subsequently carried out with enzyme linked immunosorbent assay (ELISA). Results: All study participants were male with mean age of 44 years, mean body mass index of 22.6 kg / m2 and mean onset of events of 27 months. Study subjects with reducible, irreducible, and incarcerated hernias were 45.7% (44/67 cases), 14.9% (10 / 67) and 19.4% (13/67), respectively. The mean proline level of the study subjects was 9.20. Correlation tests showed a correlation of proline levels and age (p = 0.001), body mass index (p = 0.006), and the onset of events (p = 0.023). Meanwhile, correlation of proline levels and occupation (p = 0.235) and clinical degree (p = 0.164) were not statistically significant. Conclusion: Presence if relationship between proline levels with age, and onset of incidence among indirect inguinal hernia patients.
... Collagen is the body's cement that keeps everything in place [1]. With its 28-members family it is the most important protein of vertebrates' connective tissues that accounts for the 30% of the total body protein content [2]. ...
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Type I collagen has always aroused great interest in the field of life-science and bioengineering, thanks to its favorable structural properties and bioactivity. For this reason, in the last five decades it has been widely studied and employed as biomaterial for the manufacture of implantable medical devices. Commonly used sources of collagen are represented by bovine and swine but their applications are limited because of the zoonosis transmission risks, the immune response and the religious constrains. Thus, type-I collagen isolated from horse tendon has recently gained increasing interest as an attractive alternative, so that, although bovine and porcine derived collagens still remain the most common ones, more and more companies started to bring to market a various range of equine collagen-based products. In this context, this work aims to overview the properties of equine collagen making it particularly appealing in medicine, cosmetics and pharmaceuticals, as well as its main biomedical applications and the currently approved equine collagen-based medical devices, focusing on experimental studies and clinical trials of the last 15 years. To the best of our knowledge, this is the first review focusing on the use of equine collagen, as well as on equine collagen-based marketed products for healthcare.
... Theses cellular changes result in signs inherent to both the intrinsic and extrinsic skin aging processes [4]. Collagen, a major extracellular matrix component in the dermis providing tensile strength, substantially changes with age [5]. Increased collagen fragmentation is thought to occur due to increasing matrix metalloproteinases (MMPs) expression in older skin [1]. ...
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This study aimed to investigate the potential usage of Thunbergia laurifolia Lindl. leaf extracts in the cosmetic industry. Matrix metalloproteinases (MMPs) and hyaluronidase inhibition of T. laurifolia leaf extracts, prepared using reflux extraction with deionized water (RE) and 80% v/v ethanol using Soxhlet’s apparatus (SE), were determined. Rosmarinic acid, phenolics, and flavonoids contents were determined using high-performance liquid chromatography, Folin–Ciocalteu, and aluminum chloride colorimetric assays, respectively. Antioxidant activities were determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH) and linoleic acid-thiocyanate assays. MMP-1 inhibition was investigated using enzymatic and fluorescent reactions, whereas MMP-2, MMP-9, and hyaluronidase inhibition were investigated using gel electrophoresis. Cytotoxicity on human fibroblast cell line was also investigated. The results demonstrated that SE contained significantly higher content of rosmarinic acid (5.62% ± 0.01%) and flavonoids (417 ± 25 mg of quercetin/g of extract) but RE contained a significantly higher phenolics content (181 ± 1 mg of gallic acid/g of extract; p < 0.001). SE possessed higher lipid peroxidation inhibition but less DPPH• scavenging activity than RE. Both extracts possessed comparable hyaluronidase inhibition. SE was as potent an MMP-1 inhibitor as gallic acid (half maximal inhibitory concentration values were 12.0 ± 0.3 and 8.9 ± 0.4 mg/cm3, respectively). SE showed significantly higher MMP-2 and MMP-9 inhibition than RE (p < 0.05). Therefore, SE is a promising natural anti-ageing ingredient rich in rosmarinic acid and flavonoids with antioxidant, anti-hyaluronidase, and potent MMPs inhibitory effects that could be applied in the cosmetic industry.
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Linking basic science to clinical application throughout, Histology and Cell Biology: An Introduction to Pathology, 5th Edition, helps students build a stronger clinical knowledge base in the challenging area of pathologic abnormalities. This award-winning text presents key concepts in an understandable, easy-to-understand manner, with full-color illustrations, diagrams, photomicrographs, and pathology photos fully integrated on every page. Student-friendly features such as highlighted clinical terms, Clinical Conditions boxes, Essential Concepts boxes, concept mapping animations, and more help readers quickly grasp complex information. Features new content on cancer immunotherapy, satellite cells and muscle repair, vasculogenesis and angiogenesis in relation to cancer treatment, and mitochondria replacement therapies. Presents new material on ciliogenesis, microtubule assembly and disassembly, chromatin structure and condensation, and X chromosome inactivation, which directly impact therapy for ciliopathies, infertility, cancer, and Alzheimer’s disease. Provides thoroughly updated information on gestational trophoblastic diseases, molecular aspects of breast cancer, and basic immunology, including new illustrations on the structure of the T-cell receptor, CD4+ cells subtypes and functions, and the structure of the human spleen. Uses a new, light green background throughout the text to identify essential concepts of histology – a feature requested by both students and instructors to quickly locate which concepts are most important for beginning learners or when time is limited. These essential concepts are followed by more detailed information on cell biology and pathology. Contains new Primers in most chapters that provide a practical, self-contained integration of histology, cell biology, and pathology – perfect for clarifying the relationship between basic and clinical sciences. Identifies clinical terms throughout the text and lists all clinical boxes in the table of contents for quick reference. Helps students understand the links between chapter concepts with concept mapping animations on Student Consult™ – an outstanding supplement to in-class instruction. Student Consult™ eBook version included with purchase. This enhanced eBook experience allows you to search all of the text, figures, and references from the book on a variety of devices.
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Collagen, a biopolymer finds its application in the preparation of pharmaceutical products that are used in wound management, ophthalmic, orthopaedic and oral surgeries. This wide applicability is due its special properties such as biodegradability, biocompatibility, easy availability and high versatility. Collagen is isolated from various sources such as bovine skin, fish skin, chicken skin, skin waste of marine organisms, solid wastes of leather industry, short tendons of slaughtered cattle and bone. The isolated collagen from biological wastes is found to be cost effective due to the adaptation of simple methods for its isolation when compared with other commercially available biological macromolecules. The functional groups such as amino and carboxylic acid present in collagen helps in its modification that suits for various end uses which include wound healing, ophthalmic defects, drug delivery and tissue engineering applications. These beneficial properties impart uniqueness to collagen molecule among the available bio molecules.
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Collagen is the unique, triple helical protein molecule which forms the major part of the extracellular matrix. It is the most abundant protein in the human body, representing 30% of its dry weight and is important to health because it characterizes the structure of skin, connective tissues, tendons, bones and cartilage. As collagen forms building block of body structures, any defect in collagen results in disorders, such as osteogenesis imperfecta, Ehlers-Dalnos syndrome, scurvy, systemic lupus erythematosus, systemic sclerosis, Stickler syndrome, oral submucous fibrosis, Marfan syndrome, epidermolysis bullosa, Alport syndrome. This review discusses the role of collagen in health as well as disease.
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Dynamic remodeling of the extracellular matrix (ECM) is essential for development, wound healing and normal organ homeostasis. Life-threatening pathological conditions arise when ECM remodeling becomes excessive or uncontrolled. In this Perspective, we focus on how ECM remodeling contributes to fibrotic diseases and cancer, which both present challenging obstacles with respect to clinical treatment, to illustrate the importance and complexity of cell-ECM interactions in the pathogenesis of these conditions. Fibrotic diseases, which include pulmonary fibrosis, systemic sclerosis, liver cirrhosis and cardiovascular disease, account for over 45% of deaths in the developed world. ECM remodeling is also crucial for tumor malignancy and metastatic progression, which ultimately cause over 90% of deaths from cancer. Here, we discuss current methodologies and models for understanding and quantifying the impact of environmental cues provided by the ECM on disease progression, and how improving our understanding of ECM remodeling in these pathological conditions is crucial for uncovering novel therapeutic targets and treatment strategies. This can only be achieved through the use of appropriate in vitro and in vivo models to mimic disease, and with technologies that enable accurate monitoring, imaging and quantification of the ECM.
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Collagen is a fibrillar protein that conforms the conjunctive and connective tissues in the human body, essentially skin, joints, and bones. This molecule is one of the most abundant in many of the living organisms due to its connective role in biological structures. Due to its abundance, strength and its directly proportional relation with skin aging, collagen has gained great interest in the cosmetic industry. It has been established that the collagen fibers are damaged with the pass of time, losing thickness and strength which has been strongly related with skin aging phenomena [Colágeno para todo. 60 y más. 2016. http://www.revista60ymas.es/InterPresent1/groups/revistas/documents/binario/ses330informe.pdf.]. As a solution, the cosmetic industry incorporated collagen as an ingredient of different treatments to enhance the user youth and well-being, and some common presentations are creams, nutritional supplement for bone and cartilage regeneration, vascular and cardiac reconstruction, skin replacement, and augmentation of soft skin among others [J App Pharm Sci. 2015;5:123-127]. Nowadays, the biomolecule can be obtained by extraction from natural sources such as plants and animals or by recombinant protein production systems including yeast, bacteria, mammalian cells, insects or plants, or artificial fibrils that mimic collagen characteristics like the artificial polymer commercially named as KOD. Because of its increased use, its market size is valued over USD 6.63 billion by 2025 [Collagen Market By Source (Bovine, Porcine, Poultry, Marine), Product (Gelatin, Hydrolyzed Collagen), Application (Food & Beverages, Healthcare, Cosmetics), By Region, And Segment Forecasts, 2014 – 2025. Grand View Research. http://www.grandviewresearch.com/industry-analysis/collagen-market. Published 2017.]. Nevertheless, there has been little effort on identifying which collagen types are the most suitable for cosmetic purposes, for which the present review will try to enlighten in a general scope this unattended matter.
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Collagen has been studied extensively by a large number of research laboratories since the beginning of the 20th century. Collagens are the major fibrous glycoproteins present in the extracellular matrix and in connective tissue such as tendons, cartilage, the organic matrix of bone, and the cornea, and they maintain the strength of these tissues. Collagen has a triplehelical structure. This molecule consists of repeating unusual amino acids 35% glycine, 11% alanine, 21% proline, and hydroxyproline. The importance of collagens was clearly defined after the inherited collagen disorder studies. Mutations that alter folding of the triple helix result in identifiable genetic disorders, such as: osteogenesis imperfecta, Ehlers-Danlos syndromes, Alport syndrome, Bethlem myopathy, some subtypes of epidermolysis bullosa, Knobloch syndrome, some osteoporoses, arterial aneurysms, osteoarthrosis, and intervertebral disc diseases. The collagen family will be one of the most important research topics in future years because of its many important functions.