Extracellular Matrix (ECM) are collection of extracellular molecules secreted by cells that provides structural and biochemical support to the surrounding cells. They are substances containing Collagen, Elastin, Proteoglycans, Glycosaminoglycans and fluid produced by the cells they are embedded. They fill the spaces between the cells in a tissue protecting them and holding them together. They are the natural support Structures of the cells.  The extracellular matrix may be semifluid or rigidly solid and hard as in bone. Each type of connective tissue in animals has a type of ECM: collagen fibers and bone mineral comprise the ECM of bone tissue; reticular fibers and ground substance comprise the ECM of loose connective tissue; and blood plasma is the ECM of blood. Some common function of the Extracellular Matrix includes cell adhesion; cell-to-cell communication and cell differentiation.

1. PHYSICAL PROPERTIES OF THE EXTRACELLULAR
MATRIX
PRESENTED BY FELIX CHIBUZO OBI (20144610)
BIOMEDICAL ENGINEERING, MSc
Email: felix4excel@yahoo.com
SUPERVISED BY ASSO. PROF. TERIN
ADALI
FACULTY OF ENGINEERING
DEPARTMENT OF BIOMEDICAL
ENGINEERING

2. Presentation Outline
• INTRODUCTION
• PHYSICAL STRUCTURES OF THE EXTRACELLULAR MATRIX
• COMPOSITION OF THE EXTRACELLULAR MATRIX.
• MACHANICAL PROPERTIES OF THE EXTRACELLULAR MATRIX
• CONCLUSION
• REFERENCES
PHYSICAL PROPERTIES OF THE EXTRACELLULAR MATRIX, FELIX C. O. 2016 2

3. INTRODUCTION
Extracellular Matrix (ECM) are collection of extracellular
molecules secreted by cells that provides structural and
biochemical support to the surrounding cells. They are
substances containing Collagen, Elastin, Proteoglycans,
Glycosaminoglycans and fluid produced by the cells they are
embedded. They fill the spaces between the cells in a tissue
protecting them and holding them together. They are the
natural support Structures of the
cells. The extracellular matrix may be semifluid or rigidly solid a
nd hard as in bone. Each type of connective tissue in animals
has a type of ECM: collagen fibers and bone mineral comprise
the ECM of bone tissue; reticular fibers and ground
substance comprise the ECM of loose connective tissue;
and blood plasma is the ECM of blood. Some common function
of the Extracellular Matrix includes cell adhesion; cell-to-cell
communication and cell differentiation.
PHYSICAL PROPERTIES OF THE EXTRACELLULAR MATRIX, FELIX C. O. 2016
3

4. PHYSICAL STRUCTURES OF THE EXTRACELLULAR MATRIX
• They may be semifluid or rigidly solid and hard a
s in bone.
• They are network of proteins and carbohydrates
that surrounds the cells and fill the intercellular
spaces.
• They are composed of an interlocking mesh of
Fibrous proteins and Glycosaminoglycans
(GAGs).
PHYSICAL PROPERTIES OF THE EXTRACELLULAR MATRIX, FELIX C. O. 2016
4

5. COMPOSITION OF THE EXTRACELLULAR MATRIX.
• Because multicellularity evolved independently in different
multicellular lineages, the composition of ECM varies between
multicellular structures. However, the two main Classes of
molecules that make up the Extracellular Matrix are Fibrous
Proteins and Proteoglycans, other molecules include Water,
Electrolytes and Minerals. These Components are produced
and organized by the Cells that are embedded within them.
They Fibroblast (Fiber making cells) are commonly charged
with this responsibility. There are four principles classes of
Fibrous Protein found in the Extracellular Matrix namely;
Collagen, Elastin, Fibronectin and Laminin. Proteoglycans are
composed of Protein core surrounded by long chains of
Starch-like molecules called Glycosaminoglycans (GAG).
Let’s take a look at these Molecules.
PHYSICAL PROPERTIES OF THE EXTRACELLULAR MATRIX, FELIX C. O. 2016
5

6. COLLAGEN
• Collagens are strong stretch-
resistant fibers that provide
tensile strength to the
tissues. They are the most
abundant proteins in the
human body and are the
principle constituent of the
tendons and ligament. They
are also known to provide
support to the skin and help
in wound healing.
PHYSICAL PROPERTIES OF THE EXTRACELLULAR MATRIX, FELIX C. O. 2016
6

7. ELASTINS
PHYSICAL PROPERTIES OF THE EXTRACELLULAR MATRIX, FELIX C. O. 2016
7
Elastin is a stretchy and resilient
protein that gives elasticity to the
tissues, allowing them to stretch
when needed and then return to
their original state. They are
useful in blood vessels,
the lungs, and skin and these
tissues contain high amounts of
Elastin. They are synthesized
by fibroblasts and smooth
muscle cells.

8. FIBRONECTIN
PHYSICAL PROPERTIES OF THE EXTRACELLULAR MATRIX, FELIX C. O. 2016
8
Fibronectins are glycoprotein that
connect cells with collagen fibers in
the Extracellular Matrix, allowing
cells to move through the Matrix.
Fibronectins bind collagen and cell-
surface integrins, causing a
reorganization of the
cell's cytoskeleton to facilitate cell
movement. Fibronectins are secreted
by cells in an unfolded, inactive form.
Binding to integrins unfolds
Fibronectin molecules, allowing them
to form dimers so that they can
function properly. Fibronectins also
help at the site of tissue injury by
binding to platelets during blood
clotting and facilitating cell
movement to the affected area
during wound healing.
The Human Fibronectin

9. LAMININ
PHYSICAL PROPERTIES OF THE EXTRACELLULAR MATRIX, FELIX C. O. 2016
9
Laminins are proteins found in
the basal laminae of virtually all
animals. They form sheet-like
network that serves as the “glue”
between dissimilar tissues. They
also assist in cell adhesion.
Laminins bind other ECM
components such as collagens,
nidogens, and entactins. Laminin
are the principle proteins in the
basement membrane. Basement
membranes are sheet-like
depositions of ECM on which
various epithelial cells rest.

10. PROTEOGLYCANS
PHYSICAL PROPERTIES OF THE EXTRACELLULAR MATRIX, FELIX C. O. 2016
10
Proteoglycans are a combination of
proteins and Glycosaminoglycans.
Glycosaminoglycans (GAGs)
are carbohydrate polymers and are
usually attached to extracellular matrix
proteins to form Proteoglycans.
Proteoglycans have a net negative
charge that attracts positively charged
sodium ions (Na+), which attracts water
molecules via osmosis, keeping the ECM
and resident cells hydrated.
Proteoglycans may also help to trap and
store growth factors within the ECM.
http://study.com/academy/lesson/extracellular-matrix-function-
components-definition.html
(The Video: Composition of the ECM)

11. MACHANICAL PROPERTIES OF THE EXTRACELLULAR MATRIX
The ECM can exist in varying degrees
of stiffness and elasticity, from soft brain tissues to hard
bone tissues, the elasticity of the ECM can differ by
several orders of magnitude. This property is primarily
dependent on collagen and elastin concentration, and it
has recently been shown to play an influential role in
regulating numerous cell functions.
Cells can sense the mechanical properties of their
environment by applying forces and measuring the
resulting backlash. This plays an important role because
it helps regulate many important cellular processes
including cellular contraction, cell migration, cell
proliferation, differentiation and cell death (apoptosis).
PHYSICAL PROPERTIES OF THE EXTRACELLULAR MATRIX, FELIX C. O. 2016
11

12. PHYSICAL PROPERTIES OF THE EXTRACELLULAR MATRIX, FELIX C. O. 2016 12
As said earlier, Collagen provides tissues with strength and
stiffness, which serve to protect them against fracture under
an applied force. Collagen in mammalian tendon has a
strength of ~0.12 GPa, just one order of magnitude lower
than high tensile steel [2,104], and an elastic modulus of ~1.2
GPa, demonstrating substantial material stiffness. The table
below summarizes the Mechanical properties of Collagen
and Elastin.

13. CONCLUSION
Extracellular Matrix are the natural support structures of the cell,
they are mainly made up of fibrous proteins and Proteoglycans. Of
all the molecules in the Extracellular Matrix, Collagen and Elastin
play major role in the mechanical properties of the ECM. They
assemble into fibrous extracellular networks that fulfill crucial
structural and mechanical roles supporting tissue function. These
two proteins form cross-linked fibers from monomeric units, but till
exhibit remarkably different mechanical properties and mechanisms
of mechanical response. The result is a resilient matrix that enables
tissues to cope with a range of forces spanning biological relevance.
Due to their impressive suite of mechanical properties, these
proteins present a tempting direction for biomedical applications,
including wound healing, tissue regeneration, and the rational
design of mimetic biomaterials. Such design requires recapitulation
of mechanical properties, which necessitates a thorough
understanding of the relationship between sequence, structure and
assembly as they apply to function.
PHYSICAL PROPERTIES OF THE EXTRACELLULAR MATRIX, FELIX C. O. 2016
13

14. REFERENCES
Extracellular Matrix: Function, Components & Definition
http://study.com/academy/lesson/extracellular-matrix-function-components-
definition.html
(Video: downloaded on the 25th January, 2016)
Lisa D. Muiznieks, Fred W. Keeley; Molecular assembly and mechanical properties of
the extracellular matrix: A fibrous protein perspective. journal homepage:
www.elsevier .com/locate/bbadis
Wikipedia, the free Encyclopedia; Extracellular matrix
https://en.wikipedia.org/wiki/Extracellular_matrix
A.W. Clarke, E.C. Arnspang, S.M. Mithieux, E. Korkmaz, F. Braet, A.S. Weiss,
Tropoelastin massively associates during coacervation to form quantized
protein spheres, Biochemistry 45 (2006) 9989–9996.
Y. Tu, A.S.Weiss, Transient tropoelastin nanoparticles are early-stage intermediates
in the coacervation of human tropoelastin whose aggregation is facilitated by
heparan sulfate and heparin decasaccharides, Matrix Biol. 29 (2010) 152–159.
PHYSICAL PROPERTIES OF THE EXTRACELLULAR MATRIX, FELIX C. O. 2016 14

15. PHYSICAL PROPERTIES OF THE EXTRACELLULAR MATRIX, FELIX C. O. 2016 15
T.J. Broekelmann, B.A. Kozel, H. Ishibashi, C.C. Werneck, F.W. Keeley, L.
Zhang,
R.P. Mecham, Tropoelastin interacts with cell-surface glycosaminoglycans via
its COOH-terminal domain, J. Biol. Chem. 280 (2005) 40939–40947.
N. Perrimon, M. Bernfield, Specificities of heparan sulphate proteoglycans in
developmental processes, Nature 404 (2000) 725–728.
D. Gheduzzi, D. Guerra, B. Bochicchio, A. Pepe, A.M. Tamburro, D. Quaglino, S.
Mithieux, A.S. Weiss, I. Pasquali Ronchetti, Heparan sulphate interacts with
tropoelastin, with some tropoelastin peptides and is present in human dermis
elastic fibers, Matrix Biol. 24 (2005) 15–25.
W.J. Wu, B. Vrhovski, A.S. Weiss, GlycosaT.J. Broekelmann, B.A. Kozel, H.
Ishibashi, C.C. Werneck, F.W. Keeley, L. Zhang,
R.P. Mecham, Tropoelastin interacts with cell-surface glycosaminoglycans via
its COOH-terminal domain, J. Biol. Chem. 280 (2005) 40939–40947.
N. Perrimon, M. Bernfield, Specificities of heparan sulphate proteoglycans in
developmental processes, Nature 404 (2000) 725–728.

16. PHYSICAL PROPERTIES OF THE EXTRACELLULAR MATRIX, FELIX C. O. 2016 16