Cartilage tissue engineering: current scenario and challenges

Review Article Adv. Mat. Lett. 2011, 2(2), 90-99 ADVANCED MATERIALS Letters
more proteins that can stick to cells to enhance cellscaffold
interaction.
8. Obstacles and future perspectives in cartilage
regeneration
A number of obstacles in the way of optimal cartilage
repair remain to be surmounted. These hurdles are
associated with the three cornerstones of cartilage tissue
engineering: cells, scaffold and growth factors. The major
challenging issues associated with cartilage tissue
engineering are summarised in Fig. 11. The key cell related
issue is how to enhance chondrogenesis, and how
biophysical, chemical and mechanical stimuli can be
introduced within the cells to promote chondrogenesis.
Major scaffold related issue includes the fabrication of
scaffold in such a way that can exactly mimic the natural
environment of the tissue. As far as growth factors are
concerned, very little is known about the sequences and
concentrations of growth factors for which cartilage
regeneration is optimized.
Although cartilage regeneration is complex and affected
by multiple growth factors which are released in a wellorchestrated
manner, but most of the studies involved use
of single growth factor. A little number of systems have
been developed been developed that allow the biphasic
release of dual growth factors. An example is the
encapsulation of IGF-1 in gelatin spheres that are then
suspended in oligo[poly(ethylene glycol) fumarate]
scaffolds containing TGF-1.This system provides a fast
release of TGF-1 and a more sustained delivery of IGF-1
to promote cartilage repair [56]. Dual growth factor
releasing alginate based nanoparticle/hydrogel system was
recently used to deliver BMP-7 and TGFβ-2 to promote
Fig. 11. Major challenging issues in cartilage tissue engineering.
chondrogenesis in MSCs [57]. Thus, there is a need to
focus on the study of releasing multiple growth factors at a
time, to favour the production of more natural cartilage
tissue.
Furthermore, it should be kept in mind that most of the
studies in cartilage tissue engineering were performed using
mostly young adult and even fetal animal cells, and not with
cells from elderly osteoarthritis patients. Therefore,
extensive research on using the cells from elderly
osteoarthritis patients will be needed to extend the results
for treating human cartilage defects.
The final and probably most difficult problem is how to
translate the results of in vitro and animal studies into
clinical application and thereby introduction to market. To
date, a large number of new cartilage products and growth
factor carrier materials have been developed, but only few
of them are approved for use in patients. Some of the major
reasons for the small numbers of approved products
include, hurdles posed by the cost of development, cost of
goods, manufacturing scale-up, sterility and patent issues.
In addition, there are many regulatory hurdles, including
quality control and quality assurance for consistent
manufacturing, comparability studies required for
component and process changes, establishment of shipping
and storage conditions, and appropriate shelf life [58].
Already existing as well as new cartilage engineering
products should be approved by the government
organizations so that they can be easily available for
clinical applications. Most importantly, major efforts are
needed to move the obtained results in laboratory towards
the application for treating human cartilage defects [58].
This can be solved, to certain extent, by making the cost
effective tissue engineered products. Moreover, the tissue
engineered solution for cartilage repair must involve
minimal donor site morbidity and should be free of any
Adv. Mat. Lett. 2011, 2(2), 90-99 Copyright © 2011 VBRI press. 97