Bilayered Scaffolds for Osteochondral Tissue Engineering

Abstract

Osteoarthritis (OA) is a prevalent degenerative joint disease that places a significant burden on the socioeconomic efficacy of communities around the world. Tissue engineering repair of articular cartilage in synovial joints represents a potential OA treatment strategy superior to current surgical techniques. In particular, osteochondral tissue engineering, which promotes the simultaneous regeneration of articular cartilage and underlining subchondral bone, may be a clinically relevant approach toward impeding OA progression. The unique and complex functional demands of the two contrasting tissues that comprise osteochondral tissue require the use of bilayered scaffolds to promote individual growth of both on a single integrated implant. This paper reviews the three current bilayered scaffold strategies applied to solve this challenging problem, with a focus on the need for an innovative approach to design and fabrication of new optimized scaffold combinations to reinforce materials science as an important element of osteochondral tissue engineering.

Bioengineering of Articular Cartilage: Past, Present and Future

“…However PGA also exhibits a high degradation rate and low solubility in most organic compounds due to its highly crystalline structure. This can result in the accumulation of degradation products which can cause inflammatory reactions [97,98].…”

“…Degradation by-products has been shown to elicit inflammatory response and decreased pH level [98] Mechanical stiffness can sometimes be undesirable [196] Hydrophobicity [196] [197]; [198]; [199]; [197]; [200]; [201]; [202]; [203]; [204]; [205];;…”

Composite Scaffolds for Orthopaedic Regenerative Medicine

“…This has been recognised within the field and more and more we are seeing the emergence of multi-layered scaffolds, attempting to regenerate multiple tissue types in vivo. The use of bi-layered scaffolds allows the development of optimised, tissuespecific biological environments within each respective layer via variations in mechanical, structural, and chemical properties (O'Shea et al, 2008). These scaffolds can be designed to better mimic the native ECM for each tissue type independently rather than trying to fabricate a construct that attempts to compensate for the functional requirements of both cartilage and bone in a single structure but fail to address the mechanical and biological need for an intermediate calcified cartilage phase to comprehensively integrate these distinct tissue types in vivo.…”

“…Although multi-layered scaffolds can be fabricated by the combination of individually fabricated layers, standard techniques for combining these layers (such as suturing and gluing) are problematic from both a mechanical and a biological point of view. Currently, bi-layered scaffolds with a seamlessly integrated structure are only available composed of synthetic materials (Ghosh et al, 2008) with one exception (Chondromimetic, Tigenix) and although these multi-layered constructs have shown promise in vitro, a significant amount of in vivo data needs to be gathered regarding their clinical efficacy (O'Shea et al, 2008). Consequently, the ability to fabricate multi-layer natural scaffolds exhibiting layerspecific composition, porosity, pore size, mechanical properties, degradation rate and permeability as part of a seamlessly integrated construct is of significant interest.…”

Tissue engineering: use of scaffolds for ligament and tendon healing and regeneration

“…I would like to further encourage the readers to examine a recent review paper on bilayer scaffolds designed for osteochondral tissue engineering [8]. There, the current status of synthetic polymers [such as poly (lactic acid) (PLA) and poly (glycolic acid) (PGA)], and bioceramics [hydroxyl carbonate apatite (HCA)], were beautifully reviewed.…”