Injectable hydrogel microspheres in cartilage repair

The key to regenerative medicine is in situ regeneration of lesion cells, so as to achieve lesion repair and regeneration. However, the complex environment of the joint cavity where cartilage is located leads to poor efficacy of traditional therapies to promote cartilage repair and regeneration. Development of hydrogel microspheres offers an attractive solution for regenerative medicine aimed at cartilage repair to address these limitations. Hydrogel microspheres have the potential of injectable and multi-functional transformation, which can effectively regulate the pathophysiological changes of cells and extracellular matrix at the site of cartilage injury. This review summarizes the application of various functional modified hydrogel microspheres in cartilage repair and regeneration. The common techniques and biomaterials used to prepare hydrogel microspheres are first briefly introduced. In particular, the microfluidic technology is highlighted in detail. Besides, the construction strategies of hydrogel microspheres with different functions and their mechanisms to promote cartilage repair and regeneration are further presented. Finally, the problems and challenges of hydrogel microspheres for cartilage repair are summarized.