"The development of hydrogels for regenerative medicine has progressed to the point where they are now considered one of the best options for successfully regenerating injured tissues. Their structural similarities to the extracellular matrix (ECM) and their versatility make them excellent candidates to mimic a native environment. Indeed, they are easily chemically modified and can be tuned to exhibit adequate degradation profile and mechanical integrity, as well as to incorporate growth factors or cytokines, making them suitable microenvironments to guide cell infiltration, proliferation, migration and differentiation, as well as innovative delivery systems of cells, extracellular vesicles or nucleic acids. Injectable hydrogels are the most extensively studied as they offer unmatched advantages compared to other biomaterials. As fluid materials, they have the ability to set in situ by physical or chemical crosslinking to form 3D microenvironments, thus simplifying their injection during minimally invasive surgery. Moreover, the development of dynamic chemistries now allows the use of hydrogels as nearly-physiological matrices to recapitulate the dynamic interactions of native environments.
In this talk, we will first provide an overview of the polymers, chemistries and fabrication techniques that are used to develop injectable hydrogels. We will highlight promising strategies that are used for tissue regeneration, notably in the field of joint diseases. We will then look at cell microencapsulation approaches with natural polymers (hyaluronic acid, alginate). Recent advances in droplet-based microfluidics and micromolding technologies will be discussed. We will also highlight the requirements in terms of diffusion and size properties, outline the 3D microenvironments we have recently developed in our lab using soft lithography technique, and discuss their relevance in the context of osteoarthritis and intervertebral disc treatment. "