Injectable biomaterials for translational medicine

Injectable therapeutics enabled by engineered biomaterials are becoming increasingly popular, transforming traditional clinical practice to become a minimally invasive and regenerative regime. Compared to preformed biomaterials, injectable biomaterials allow for more precise implantation into deeply enclosed anatomical locations and for the repair of irregularly shaped lesions, demonstrating great translational potential. Continuously emerging clinical needs and advances in materials science have driven an evolution in injectable biomaterials from structural fillers to multifunctional platforms. Integrating disparate functions to design injectable biomaterials for clinical translation remains a considerable challenge, as does the selection of the appropriate design considerations for specific applications. This article aims to review the design and fabrication considerations of injectable biomaterials in the context of medical translation, the engineering strategies used for new materials to meet the growing demands in regenerative and intelligent medicine, and the progress in their development for selected clinical applications. Specifically, three exemplary areas, injectable bone cements, hydrogels, and electronics, all of which demonstrate significant promise in terms of translation and commercialization, are reviewed in detail. In addition, their translational status and future challenges are discussed. It is also envisioned that the mutual collaboration between researchers, clinicians, entrepreneurs, engineers, and patients will inspire and catalyze the innovation and translation of injectable biomaterials.