Cartilage is highly important to joint function. In healthy joints, cartilage tissue provides a gliding surface that prevents friction during movement.
Additionally, cartilage acts as a shock absorber to prevent damage to underlying bone. Damage to cartilage leads to many different healthcare issues, the most commonly known being osteoarthritis.
As a result, there is a great demand for scientists to develop ways of helping the body to naturally repair and regenerate damaged cartilage. One popular method involves designing a cell ‘scaffold’ which can be implanted into damaged tissue, promoting regeneration.
A recent advancement in this type of research has come from a collaborative effort between research groups in China, Hong Kong and Singapore with the development of an implantable scaffold that actively enhances cartilage regeneration in animal tissue.
Design of the Scaffold
The scientists involved in this study designed a scaffold made of chitosan, a naturally available polysaccharide that is often utilised in this field.
However, the team of researchers modified the scaffold to include transforming growth factor beta (TGF-β1), which plays an important role in cartilage formation.
In order to test the potential of their scaffold, the research group designed two different types of experiment.
The first experiment involved incorporation of stem cells into their scaffold and implantation into mice. After 4 weeks, the tissue area surrounding the implant was analysed, revealing evidence of new cartilage forming from the implant.
Building on this, the team then implanted their scaffold into rabbits with knee defects.
This time, however, no stem cells were incorporated into the scaffold before implantation. After 6 months, the condition of the damaged tissue was assessed and the results were extremely promising.
The researchers observed significant healing in rabbits treated with their scaffold implants. This was due to the way in which the scaffold interacts with surrounding tissue.
TGF-β1 within the scaffold causes stem cells to be recruited from within the rabbit’s bone marrow, kick-starting repair of damaged tissue.
Data from the rabbit study is particularly promising when it comes to applying this system to healthcare issues.
Currently, treatments for conditions such as osteoarthritis are limited to managing symptoms. This is because we still don’t have a clinically approved way of regenerating cartilage tissues in affected patients.
Treatments still rely heavily on full joint replacements, many of which never truly integrate into a patient’s body. They provide pain relief and some improvement but full joint function never returns.
However, a system such as this approaches the problem from a different perspective. Instead of using an implant to replace damaged tissue, the specially designed scaffold simply provides a platform on which a patient’s body can repair itself.
By implanting this simple, economical and highly effective material, the body’s natural process of tissue regeneration can be initiated. Hopefully, further testing of systems like this will lead to development of a safe and successful strategy for cartilage regeneration.
Chen, J., Li, Y., Wang, B., Yang, J., Heng, B. C., Yang, Z., Ge, Z. & Lin, J. 2018
TGF-[small beta]1 affinity peptides incorporated within a chitosan sponge scaffold can significantly enhance cartilage regeneration
Journal of Materials Chemistry B., January 2018, DOI 10.1039/C7TB02132A
Image: Growing bone by Karin Hing. Credit: Wellcome Collection. CC BY