Three-dimensional (3D) bioprinting fabricates 3D functional tissues/organs by accurately depositing the bioink composed of the biological materials and living cells. Even though 3D bioprinting techniques have experienced significant advancement over the past decades, it remains challenging for 3D bioprinting to artificially fabricate functional tissues/organs with high post-printing cell viability and functionality since cells endure various types of stress during the bioprinting process. Generally, cell viability which is affected by several factors including the stress and the environmental factors, such as pH and temperature, is mainly determined by the magnitude and duration of the stress imposed on the cells with poorer cell viability under a higher stress and a longer duration condition. The maintenance of high cell viability especially for those vulnerable cells, such as stem cells which are more sensitive to multiple stresses, is a key initial step to ensure the functionality of the artificial tissues/organs. In addition, maintaining the pluripotency of the cells such as proliferation and differentiation abilities is also essential for the 3D-bioprinted tissues/organs to be similar to native tissues/organs. This review discusses various pathways triggering cell damage and the major factors affecting cell viability during different bioprinting processes, summarizes the studies on cell viabilities and functionalities in different bioprinting processes, and presents several potential approaches to protect cells from injuries to ensure high cell viability and functionality.

With the aim of further enhancing the bioactive performance of Ti–6Al–4V, ultrasonic‐assisted microarc oxidation (MAO) and hydrothermal (HT) treatments are combined to produce denser, more uniform hydroxyapatite (HA) crystals on the MAO coating herein. More Ca elements can be deposited on the coating and more TiO2 can be generated to form a thicker coating via ultrasonic assistance. Meanwhile, the MAO coating with ultrasonic assistance avoids the appearance of heterogeneous areas and homogenizes the distribution of elements. Those positive effects of ultrasonic‐assisted MAO coating provide favorable conditions for the subsequent HT treatment to form dense and uniform HA crystals. In vitro experiment shows that the ultrasonic‐assisted MAO coating has a higher number of MG63 cells compared with other samples. Moreover, the formation of HA crystals improves the biological activity of all samples. In the ultrasonic‐assisted sample after HT treatment, denser and more uniform HA crystals on the coating surface result in the higher alkaline phosphatase activity of the sample.