4D bioprinting of tissues and organs

Abstract

Progress in materials science has developed the boundaries of additive manufacturing (AM) technology by offering a breathtaking forum for interdisciplinary research in medical science. Recently, with a growing interest in stimuli-responsive materials, a new concept called four-dimensional (4D) bioprinting, which has determined time as the 4th dimension, has been introduced. This technique proceeds on the assumption that after three-dimensional (3D) bioprinting, tissues need to remodel and mature. 4D bioprinting aims to fabricate complex constructs that have the inherent ability to transform their properties upon response to internal or external stimuli so as to repair, regrow, or replace diseased or damaged cells, tissues, and ultimately organs. Accordingly, autografts, which trigger donor site morbidity and need invasive surgeries, might be replaced by 4D bioprinted scaffolds, leading to numerous applications in the biomedical field. However, 4D bioprinting is still in its early stages, and further research should focus on this state-of-the-art technology. Herein, the fundamental approaches and mechanisms of 4D bioprinting are presented. The recent advances and the potential future applications of 4D bioprinting are also reviewed.