Cartilage Tissue Engineering

[Dinesh]

Hello fellow biomaterial workers,

I am current carrying out some preliminary work on the development of <b>cartilage replacements</b>.

Many people will be aware that the cartilage tissues have very limited self-regeneration capacity.
Also, the scar tissue is usually formed of a fibrous material with poor mechanical properties.

For this reason, the main treatment at the moment is surgical prosthesis. However, that may well change if tissue engineering allows cartilage to repair itself.

Tissue engineering is one new and exciting approach to achieving cartilage regeneration.
The approach involves the use of biodegradable polymeric matrixes and isolated chondrocytes from tissue biopsies. Cells are seeded inside the biocompatible matrix and then they are implanted into the damaged joint. A large number of non-degradable and degradable polymer materials have been tested for this tissue engineering application.

There was a review paper done that might interest a few of you:

<!--quoteo-->QUOTE<!--quotec-->B.L. Seal, T.C. Otero, A. Panitch, <b>Polymeric biomaterials for tissue and
organ regeneration</b>, Materials Science Reports R34 (2001) 147–230.<!--QuoteEnd--><!--QuoteEEnd-->

Several studies have been done with synthetic degradable polymers, such as polyesters
(polylactic acid (PLA), polyglycolic acid (PGA), and their copolymers), polyethylene oxide or injectable polymers like poly(ethylene glycol). Natural polymers have also been used with some success to design tissue matrixes (e.g. collagen, fibrin, gelatine, hyaluronic acid, agarose, alginate, or chitosan).

Yours,

Dinesh

[blake]

Hi Dinesh,

This article might interest you:

<!--quoteo-->QUOTE<!--quotec-->
<b>Advancing cartilage tissue engineering: the application of
stem cell technology</b>
by Joanne Raghunath, Henryk J Salacinski, Kevin M Sales,
Peter E Butler and Alexander M Seifalian

ABSTRACT: The treatment of cartilage pathology and trauma face the
challenges of poor regenerative potential and inferior repair.
Nevertheless, recent advances in tissue engineering indicate
that adult stem cells could provide a source of chondrocytes for
tissue engineering that the isolation of mature chondrocytes
has failed to achieve. Various adjuncts to their propagation and
differentiation have been explored, such as biomaterials,
bioreactors and growth hormones. To date, all tissue
engineered cartilage has been significantly mechanically
inferior to its natural counterparts and further problems in vivo
relate to poor integration and deterioration of tissue quality over
time. However, adult stem cells — with their high rate of
proliferation and ease of isolation — are expected to greatly
further the development and usefulness of tissue engineered
cartilage.

INTRO: Introduction
Cartilage is important in joints (hyaline or articular
cartilage) and for structural features (elastic cartilage),
such as the nasal septum. It has a poor regenerative
capacity and its replacement tissue, fibrocartilage, is
mechanically inferior. Chondrocytes are highly specialized
cells that secrete the extracellular matrix proteins.
The extracellular matrix of healthy hyaline cartilage
consists of collagen II (
90–95%) with lesser amounts
of collagen types VI, IX, X and XI and proteoglycans.
Fibrocartilage possesses higher amounts of collagen
type I. The mainstay treatment for articular cartilage reconstruction
is arthrodesis (joint fusion) and arthroplasty (joint
replacement), although various approaches to encourage
cartilage regeneration have been attempted [1,2]. Current
synthetic implants have a number of drawbacks,
principally infection, rejection, longevity and unsatisfactory
scarring. Despite recent advances in tissue engineering
the vascularisation of tissue remains problematic [3].
The low degree of vascularisation in cartilage, however,
makes it an ideal target for tissue engineering. Chondrocytes
are difficult to isolate in humans, replicate slowly
and are prone to phenotypic dedifferentiation in culture
[4,5]. This can be further affected by donor age and health
status [6,7]. In view of this, tissue engineering based on
these cells is unlikely to prove successful and instead
studies have focused on the use of stem cells for tissue
engineering cartilage (Figure 1). In this review, we highlight
the potential of adult stem cells (ASCs) for tissue
engineering cartilage and go on to discuss the most
successful biomaterials to exploit these cells.

<!--QuoteEnd--><!--QuoteEEnd-->

(Current Opinion in Biotechnology 2005, 16:503–509)
http://www.current-opinion.com

[blake]

Here is another related article that I came across today:

<!--quoteo-->QUOTE<!--quotec-->
<b>Same scaffold, different cells</b>

BIOMATERIALS
Researchers at the US National Institutes of
Health and Thomas Jefferson University have
generated adipose, cartilage, and bone cells
in vitro on a polymer nanofiber scaffold
seeded with stem cells [Li et al.,
Biomaterials (2005) 26 (25), 5158].

Cells grown on a biodegradable scaffold can
be used to help repair damaged tissues in
the body. Stem cells could prove useful
because they can differentiate into a variety
of specialized cell types. Ideally, a single
biomaterial scaffold should support multiple
cell types, so mimicking natural tissues.

The team immersed human mesenchymal stem
cells in an electrospun poly(ε-caprolactone),
or PCL, scaffold and induced the cells to
differentiate into different cell lineages. “The
electrospun nanofiberous scaffold… can be
considered as a candidate biomaterial
scaffold for the fabrication of a single-unitbased,
multicomponent tissue construct,”
says Wan-Ju Li.

The scaffold is effective because its 700 nm
diameter fibers imitate the collagen fibrils
that support cells in the body. The fine fibers
also provide a desirable degradation rate.
“Unlike many other biomaterials that have
been tested as scaffolds, PCL dissolves
slowly,” explains lead author Rocky S. Tuan.

“Some materials, like poly-D,L-lacic-co-glycolic
acid, will disappear after only a few days.”
“We have begun testing [the tissueengineered
constructs] in vivo and have had
preliminary success,” he adds. <b>“The goal is
to create cartilage, but that is still about
five years down the road.”</b> Tissue patches
like these could alleviate pain, while more
applications will be seen in the coming years,
he believes.

Patrick Cain
<!--QuoteEnd--><!--QuoteEEnd-->

Source: Materials Today - May 2005 page 13

They are hoping to create cartilage too (see highlighted text above).

regards, blake