Exquisite design of injectable Hydrogels in Cartilage Repair

Abstract

Cartilage damage is still a threat to human beings, yet there is currently no treatment available to fully restore the function of cartilage. Recently, due to their unique structures and properties, injectable hydrogels have been widely studied and have exhibited high potential for applications in therapeutic areas, especially in cartilage repair. In this review, we briefly introduce the properties of cartilage, some articular cartilage injuries, and now available treatment strategies. Afterwards, we propose the functional and fundamental requirements of injectable hydrogels in cartilage tissue engineering, as well as the main advantages of injectable hydrogels as a therapy for cartilage damage, including strong plasticity and excellent biocompatibility. Moreover, we comprehensively summarize the polymers, cells, and bioactive molecules regularly used in the fabrication of injectable hydrogels, with two kinds of gelation, i.e., physical and chemical crosslinking, which ensure the excellent design of injectable hydrogels for cartilage repair. We also include novel hybrid injectable hydrogels combined with nanoparticles. Finally, we conclude with the advances of this clinical application and the challenges of injectable hydrogels used in cartilage repair.

Synergistic enhancement of tendon-to-bone healing via anti-inflammatory and pro-differentiation effects caused by sustained release of Mg2+/curcumin from injectable self-healing hydrogels

“…Owing to its shear-thinning performance 41 , Cur&Mg-QCS/PF could be deposited with a syringe to form a gel with the shape of a sunflower, which retained this shape when stripped from the original interface (Figure 2 B). Injectability is crucial for biomedical applications of hydrogels, especially for easy application in the irregularly shaped supraspinatus insertion site 22 , 42 . Additionally, compared with traditional uninjectable scaffolds, injectable hydrogels can freely fill irregular lacuna between rotator cuff tendon and bone, thereby better promoting regeneration of the tendon-to-bone interface.…”

Biomimetic hydrogels designed for cartilage tissue engineering

“…In situ crosslinking of injectable hydrogels allow for a minimally invasive procedure, cell encapsulation and transplantation, and ability to match irregular defects 6 . Different methods can be applied to prepare injectable hydrogels, including physical and chemical crosslinking 63 ranging from photo crosslinking, enzymatically crosslinked hydrogels, ion or pH-sensitive hydrogels, click chemistry, etc. For instance, recent works in click-crosslinked modified HA hydrogels for cartilage tissue engineering have shown suitable mechanical properties and porous structures leading to high GAGs expression and chondrogenic differentiations of human periodontal ligament stem cells (hPLSCs) 64 .…”

Update on Novel Non-Operative Treatment for Osteoarthritis: Current Status and Future Trends

“…Various natural or synthetic materials have been explored as scaffolds in CTE to create three-dimensional (3D) tissue constructs that maintain and restore the function and structure of the cartilage. In the application of cartilage regeneration, injectable hydrogels over the solid scaffolds initiate the possibility of percutaneous injection, owing to their highly aqueous 3D cross-linked network structure ( Wu et al, 2020 ). Hydrogels are mainly composed of natural biomaterials (chitosan, fibrin, alginate, collagen, and silk), or synthetic materials (polyethylene glycol (PEG), polyvinyl alcohol (PVA), polylactic acid (PLA)) ( Liu M. et al, 2017 ; Li et al, 2019 ).…”