Why Cartilage tissue engineering??

1. Cartilage Tissue Engineering
Presented by :- Khushbu Kumari
Department of Biotechnology
Semester II
Roll no. 201631

2. Content
● Introduction about Cartilage
● Structure of Cartilage
● Why Cartilage tissue engineering
● Treatments
● Cell source
● Cell signalling molecules
● Biomaterials used in CTE

3. Introduction
What is Cartilage?
○ Cartilage is a flexible connective tissue that
is stiffer and less flexible than muscle, but
not as rigid or hard as bone.
○ Cartilages do not have blood vessels, nerves
or lymphatic ducts; instead, nutrients diffuse
through the layer of dense connective tissue
(perichondrium) surrounding the cartilage.
● Function of Cartilage
Cartilage provides shape to some parts of the
body, and acts as cushion between bones in
joints,allows gliding movement, and reduces
friction between bones.
Types of Cartilage
● Hyaline cartilage
● Elastic cartilage
● Fibrocartilage
Composition of Cartilage
Cartilage is composed of specialized cells
called chondrocytes that produce a large
amount of collagenous extracellular matrix,
abundant ground substance that is rich in
proteoglycan and collagen.
The matrix of cartilage is made up of
glycosaminoglycans, proteoglycans, collagen
fibers and, sometimes elastin.

4. Structure of Cartilage
Superficial zone
● Constitute 10-20% of total cartilage
thickness
● Chondrocytes -flat and elongated, type II
collagen fibres, densely packed, highly
cross linked and horizontally aligned.
● Highest amount of collagen and lowest
proteoglycans
Middle zone
● Constitute 40-60% of total Cartilage
volume
● Higher proteoglycan content and thicker
collagen fibrils
● Chondrocytes- spherical and in lower
content
Deep zone
● Constitute 30-40% total Cartilage thickness
● Chondrocytes- spherical and arranged in column
● Highest level of proteoglycan , collagen fibrils-
larger and perpendicular to surface
Calcified zone
● Provide barrier to diffusion from blood
vessels to bone
● Contains small number of cells embedded
in calcified matrix

5. Why Cartilage tissue engineering??
There are various several reasons by which cartilage gets damaged:-
● Injury to the joint
● Degeneration with age (osteoarthritis)
● Excessive weight
● Overuse and/or excessive activity
● Inflammation and infection
Treatments
● Bone Marrow stimulation technique
● Direct Chondral Replacement (Mosaicplasty)
● Cell based treatment (ACI and MACI)

6. Bone Marrow stimulation technique
Two small incisions on the damged
portion (one incision for arthroscope
& another for awl)
Defect is cleaned
from the remnants
Abrasion is performed by removing
about 1mm of subchondral region of
bone
Bleeding occurs and this
results into formation of super
clot
Super clot contains growth factor that
develop new cartilage

7. Direct Chondral Replacement
(Mosaicplasty) A large or small incision is made over
affected joint so that it can receive the graft
by drilling
Graft is taken from the healthy
Osteochondral tissue(non- weight bearing
portion of the knee) in the form of cylindrical
plugs of similar size
Graft is inserted into the
drilled portion and the
incision is closed
Mosaicplasty of knee

8. Cell based treatment
Autologous Chondrocyte
Implantation
Matrix-Induced Autologous
Chondrocyte Implantation

9. Cell source
Numerous cell types have been proposed for cartilage tissue applications
such as chondrocytes, bone-marrow derived
mesenchymal stem cells (MSCs), stem cells isolated from bone marrow or
embryonic stem cells because these cells exhibit a chondrogenic potential
under appropriate culture conditions.
Chondrocytes
Chondrocytes are the major cell type
present in cartilage that synthesizes and
turnover a large volume of ECM
components like collagen, hyaluronan,
glycoproteins and proteoglycans. These
cells are derived from MSCs and occupy
1–5% of the total cartilage tissue.
Mesenchymal stem cells
MSCs are multipotent progenitor cells which are able to differentiate
into a variety of connective tissues cells like cartilage, bone,
ligament fat, and tendon both in vitro and in vivo.
Currently, MSCs can be isolated from Bone Marrow, but also from
other sources like adipose tissue, articular cartilage, umbilical cord
blood, dermis, synovial membrane, synovial fluLd, muscle, etc.,
with similar phenotypic characteristics but different proliferation and
differentiation potentials.

10. Signaling molecules
Several cytokines, hormones and growth factors are known to
influence the anabolic and catabolic processes by chondrocytes.
Therefore, a number of growth factors, including transforming
growth factor (TGF-β), insulin-like growth factor (IGF-1), bone
morphogenetic proteins (BMPs), and to a lesser extent fibroblast
growth factors (FGFs) and epidermal growth factor (EGF), have been
used in cartilage tissue engineering studies in vitro to promote the
chondrogenic phenotype, to stimulate ECM production and to
promote chondrogenesis of MSCs.

11. Biomaterials
● Biomaterials mimics like ECM and provide cells with an environmental structure able to
support cell viability, proliferation and secretory activities.
● Many ECM-like scaffolds are available and have been considered for cartilage tissue
engineering.
● These biomaterials can be classified as synthetic or natural matrices, in which we can
distinguish those based on proteins or polysaccharides .
● The ideal biomaterial should be biocompatible to prevent inflammatory and immunological
reactions. It must provide a favorable environment for the 3D maintenance of chondrocyte
phenotype and be adhesive to enable attachment of the cells within the lesion. It must be
permeable to allow the diffusion of molecules, nutrients and growth factors. Finally, it should
be biodegradable enough to be integrated in the physiological processes of tissue
remodeling and ideally, should be injectable, thereby allowing for implantation by minimally
invasive surgery.

12. Biomaterials
Natural biomaterials Synthetic biomaterials
Example:-
collagen
chitosan
alginate
fibrin
cellulose, etc.
Example:-
Poly (lactic-co-glycolic acid) (PLGA)
Polymer of lactic acid (PLA)
Polycaprolactone (PCL), etc.

13. Collagen:-
Collagen represents the principal component of ECM. It’s natural protein with a triple-helix structure, which can
form a reversible gel.This protein presents excellent tissue compatibility, easily biodegradation and its degradation
products are absorbed easily without Inflammation.
In several studies have been demonstrated that a combination of collagen with chondrocytes and stem cells facilitated
cartilage tissue growth in vitro and in vivo.
For example,
● Chen et al. used bone marrow mesenchymal stem cell–seeded type II collagen scaffolds to repair cartilage defect of
the rabbits. It was observed after 8 weeks that chondrocyte-like cells with lacuna structure were found in the newly
formed tissue with no signs of Inflammation and after24 weeks it was observed that the affected tissue was almost
completely repaired .
● In another study, isolated bovine chondrocytes seeded into rhCII gels were injected subcutaneously into the back of
nude mouse model. It was observed that this complex offered the ability to promote cell proliferation and mechanical
strength for the formation of cartilage.
● In a recent study, Wang et al. used core-shell nanofibrous scaffold fabricated by collagen and poly(L-lactic
acid-co-epsilon-caprolactone) to encapsulate rhTGF-β3 and bovine serum albumin into the core of the nanofibers for
tracheal cartilage regeneration. It was reported that the proliferation and morphology analyses have indicated the
good biocompatibility of the fabricated nanofibrous scaffold and it was concluded that this scaffold could be an
effective delivery and serve as a promising tissue engineered scaffold for cartilage regeneration.
Natural scaffolds

14. Synthetic scaffolds
Due to the main disadvantage of natural materials (low mechanical properties) the researchers have tried to use
synthetic materials.
Poly (ethylene glycol) (PEG) is a polyether extensively used as material support in cartilage tissue engineering.
In several studies it was reported that when PEG is used in combination with other natural or synthetic materials
was observed an improvement strength and compression modulus .
For example, in a study it was reported that human chondrocytes encapsulated into the PEG-albumin hydroge
and subcutaneously implanted in Immunodeficient mice resulted to be a beneficial implant support for
chondrocytes because the cells maintained their characteristic genotype expressing type I and II collagen and
aggrecan. Neumann et al. obtained PEG hydrogels by reactions and encapsulated juvenile bovine chondrocytes
in the hydrogels. It was observed that chondrocytes deposited increasing amounts of sulfated glycosaminoglycan
and collagens (especially collagen type II) in the hydrogels and it was confirmed the degradation of the hydrogels

15. Reference
https://www.sciencedirect.com/topics/medicine-and-dentistry/cartilage-engineering
https://hartfordsportsorthopedics.com/autologous-chondrocyte-implantation-aci-carticel-south-wi
ndsor-enfield-glastonbury-ct/
https://biologydictionary.net/cartilage/
https://www.researchgate.net/figure/Principle-of-marrowstimulating-techniques-Marrow-stimulatin
g-techniques-rely-on-creating_fig4_41425521
https://www.hss.edu/conditions_matrix-induced-autologous-chondrocyte-implantation-MACI.asp
https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.hilarispublisher.com/open-
access/biomaterials-for-cartilage-tissue-engineering-2157-7552-1000192.pdf&ved=2ahUKEwjEu9H
1tvnwAhWmxzgGHQdUDDUQFjABegQIBBAG&usg=AOvVaw1Gke6HZuV4iMlBt7HktFqm