Bioprinting of Hydrogel-Based Drug Delivery Systems for Nerve Tissue Regeneration

Globally, thousands of people are affected by severe nerve injuries or neurodegenerative disorders. These conditions cannot always be cured because nerve tissue either does not regenerate or does so at a slow rate. Therefore, tissue engineering has emerged as a potential treatment approach. This review discusses 3D bioprinting for scaffold manufacturing, highlights the advantages and disadvantages of common bioprinting techniques, describes important considerations for bioinks, biomaterial inks, and scaffolds, and discusses some drug delivery systems. The primary goal of this review is to bring attention to recent advances in nerve tissue engineering and its possible clinical applications in peripheral nerve, spinal cord, and cerebral nerve regeneration. Only studies that use 3D bioprinting or 3D printing to manufacture hydrogel scaffolds and incorporate the sustained release of a drug or growth factor for nerve regeneration are included. This review indicates that 3D printing is a fast and precise scaffold manufacturing technique but requires printing materials with specific properties to be effective in nervous tissue applications. The results indicate that the sustained release of certain drugs and growth factors from scaffolds can significantly improve post-printing cell viability, cell proliferation, adhesion, and differentiation, as well as functional recovery compared with scaffolds alone. However, more in vivo research needs to be conducted before this approach can be used in clinical applications.