Injectable and 3D Bioprinted Polysaccharide Hydrogels: From Cartilage to Osteochondral Tissue Engineering

Abstract

Biomechanical performance of functional cartilage is executed by the exclusive anisotropic composition and spatially varying intricate architecture in articulating ends of diarthrodial joint. Osteochondral tissue constituting the articulating ends comprise superfical soft cartilage over hard subchondral bone sandwiching interfacial soft-hard tissue. The shock-absorbent, lubricating property of cartilage and mechanical stability of subchondral bone regions are rendered by extended chemical structure of glycosaminoglycans and mineral deposition, respectively. Extracellular matrix glycosaminoglycans analogous polysaccharides are major class of hydrogels investigated for restoration of functional cartilage. Recently, injectable hydrogels have gained momentum as it offers patient compliance, tunable mechanical properties, cell deliverability, and facile administration at physiological condition with long-term functionality and hyaline cartilage construction. Interestingly, facile modifiable functional groups in carbohydrate polymers impart tailorability of desired physicochemical properties and versatile injectable chemistry for the development of highly potent biomimetic in situ forming scaffold. The scaffold design strategies have also evolved from single component to bi- or multilayered and graded constructs with osteogenic properties for deep subchondral regeneration. This review highlights the significance of polysaccharide structure-based functions in engineering cartilage tissue, injectable chemistries, strategies for combining analogous matrices with cells/stem cells and biomolecules and multicomponent approaches for osteochondral mimetic constructs. Further, the rheology and precise spatiotemporal positioning of cells in hydrogel bioink for rapid prototyping of complex three-dimensional anisotropic cartilage have also been discussed.

Injectable hydrogels and nanocomposite hydrogels for cartilage regeneration

“…Considering milder conditions of physical cross‐linking, in this review we put more attention to physically cross‐linked hydrogels. Mechanisms of different types of crosslinking is reviewed in …”

“…Nowadays, in situ forming hydrogels are materials of increasing interest because of their unique ability to be injected into the body. The attractiveness of this approach lies in the fact of minimally invasive surgery as well as possibility to perfectly fill the defect and simple cell encapsulation . To obtain an ideal injectable hydrogel several requirements must be met, such as solubility in aqueous media with gelation under physiological conditions, gelation occurring at suitable rate for clinical procedure and lack of toxic by‐products upon gelation …”

“…Temperature‐sensitive hydrogels are one of the most frequently studied stimuli‐responsive hydrogels. The sol–gel transition occurs either above or below critical solution temperature (CST), termed as lower (LCST) and upper critical solution temperature (UCST) . Hydrophobic interactions and hydrogen bonding play an essential role in the cross‐linking mechanism of these hydrogels.…”

Bioprinting of osteochondral tissues: A perspective on current gaps and future trends

“…Solving this challenge plays a crucial role in improving the osteochondral tissue regeneration process and graft integration with host tissue [77] . Many of the limitations for traditional osteochondral tissue engineering approaches can be attributed to the inability of precise spatiotemporal and temporal control of biomechanical and biochemical cues for direct cell migration, differentiation and cell-cell interaction.…”

Use of Polysaccharide Hydrogels in Drug Delivery and Tissue Engineering

“…These are used for the development of highly potent biomimetic in situ forming scaffolds. 3 Chitosan based thermosensitive hydrogels are also prepared which show high mechanical strength. cHA-Dex gel has better chondroprotective and anti-inflammatory effects in rat surgery-induced osteoarthritis than cHA alone.…”