Introduction
Articular cartilage is a highly specialised tissue found covering the surfaces of the bony ends of all synovial joints in the human body. Its function is to lubricate joint movement and absorb small shock impacts within a joint. The structure and composition of articular cartilage is highly ordered into distinct but seamlessly integrated layers which vary in composition and structure according to the distance from the surface.
Cartilage has a poor ability to regenerate itself due to the sparse distribution and low mitotic activity of the articular chrondrocytes and the avascular nature of the tissue. Superficial damage to the articular cartilage almost inevitably leads to the development of osteoarthritis (OA) within a joint. Cartilage damage and osteoarthritis affect at least 40 million Americans alone per annum, with an associated cost of approximately $105 billion. OA is estimated to be the fourth leading cause of disability by 2020; affecting 10% of men and 18% of women aged over 60 years in Europe.
Technology
New technology developed at RCSI consists of a layered scaffold consisting of collagen and hydroxyapatite for osteochondral repair. This technology is a tissue‐engineered scaffold made up of three distinct layers, specifically designed to closely mimic both the morphology and composition of healthy anatomical osteochondral tissue. Specifically, the three layers serve to mimic the overlying cartilaginous layer, the underlying and intermediate articular calcified cartilage and the lower subchondral bone. This scaffold is produced using an “iterative freeze‐drying’’ technique, wherein a base layer is produced through a freeze‐drying process.
Applications
• Osteoarthritis (shoulder, knee)
• Rheumatoid arthritis
• Menisectomy
• Sports injuries that damage either the cartilage or its intimately associated subchondral bone
(rotator cuff reconstruction)
• Appendicular Degenerative Joint Diseases (Ankle joint repair, hand & foot arthritis repair)
• Reconstruction of fractures within the joint
• Chondromalacia
• Spinal repair (intervertebral disc repair)
• Osteochondritis Dissecans
There is a clear requirement for a scaffold that closely mimics the layered structure and gradient composition of articular cartilage. The use of a scaffold within the defect site has been shown to result in better quality repair tissue and to allow better retention of cells within the defect site.
The novel cartilage repair scaffold described here may be implanted into osteochondral defects for osteochondral tissue regeneration i.e. repair of bone, cartilage and calcified cartilage that line the surface of any moving joint throughout the body. The scaffold is specifically fabricated to closely match osteochondral defects in terms of both anatomical morphology and composition. The use of a scaffold within the defect site has been shown to result in better quality repair tissue and to allow better retention of cells within the defect site.
Advantages
Current surgical repair techniques include osteochondral grafting, bone marrow stimulation techniques and autologous chonrdocyte implantation, all of which have associated problems. Current scaffolds on the market do not adequately mimic cartilage and as a result repair tissue that is formed is of poor quality. This technology overcomes problems with existing technologies as the iterative layering process results in a good interfacial adhesion between the scaffold layers. The features and benefits of this technology are summarised in the table below.
Feature
Benefit
Scaffold structure and composition which mimics that of articular cartilage
Promotes rapid healing by facilitating cell migration and natural cartilage regrowth
Seamless layer integration
Negates requirement for additional material (eg glue) which can adversely affect cellular response
Homogenous pore structure
This allows optimal cellular attachment and proliferation
High porosity
This allows maximum cell infiltration
Controllable biodegradation
Facilitates degradation of material in line with natural healing
Individually controllable scaffold layer properties
Complicated composition of different anatomical osteochondral tissue can be replicated.
Contacts:
Dr Aoife Gallagher, RCSI Technology Transfer, 123 St Stephen’s Green, Dublin 2, Ireland.
Email: aoifegallagher1@rcsi.ie. Tel: +353 1 4022394
Dr. Gearóid Tuohy, RCSI Technology Transfer, 123 St Stephen’s Green, Dublin 2, Ireland.
Email: gearoidtuohy@rcsi.ie Tel: +353 1 4022362
Dr Liz Moran, Enterprise Ireland, East Point Business Park, Dublin 3.
Email: liz.moran@enterprise‐ireland.com. Tel: +353 1 7272696
Principle Investigator:
Dr. John Gleeson, Department of Anatomy, Royal College of Surgeons, 123 St Stephen’s Green, Dublin 2, Ireland. Email: johngleeson@rcsi.ie. Tel: +353 1 4028536