Biomechanical factors in three-dimensional tissue bioprinting

Abstract

3D bioprinting techniques have shown great promise in various fields of tissue engineering and regenerative medicine. Yet, creating a tissue construct that faithfully represents the tightly regulated composition, microenvironment, and function of native tissues is still challenging. Among various factors, biomechanics of bioprinting processes play fundamental roles in determining the ultimate outcome of manufactured constructs. This review provides a comprehensive and detailed overview on various biomechanical factors involved in tissue bioprinting, including those involved in pre, during, and post printing procedures. In preprinting processes, factors including viscosity, osmotic pressure, and injectability are reviewed and their influence on cell behavior during the bioink preparation is discussed, providing a basic guidance for the selection and optimization of bioinks. In during bioprinting processes, we review the key characteristics that determine the success of tissue manufacturing, including the rheological properties and surface tension of the bioink, printing flow rate control, process-induced mechanical forces, and the in situ cross-linking mechanisms. Advanced bioprinting techniques, including embedded and multi-material printing, are explored. For post printing steps, general techniques and equipment that are used for characterizing the biomechanical properties of printed tissue constructs are reviewed. Furthermore, the biomechanical interactions between printed constructs and various tissue/cell types are elaborated for both in vitro and in vivo applications. The review is concluded with an outlook regarding the significance of biomechanical processes in tissue bioprinting, presenting future directions to address some of the key challenges faced by the bioprinting community.

A 3D Bioprinted In Vitro Model of Pulmonary Artery Atresia to Evaluate Endothelial Cell Response to Microenvironment

“…This could be attributed to enhanced mass transport within printed constructs, due to the formation of micro porosities that are inherent to the layer‐by‐layer deposition of materials. [ 41,52 ] Further, the 3D printed perfused group showed a higher cell growth compared to the static prints (Figure 4B), which could mainly due to enhanced mass transport (diffusion and convection [ 53,54 ] ) and the removal of metabolic stresses on the cells as a result of flow, as confirmed by the bioprofiling analysis (Figure 4C,D).…”

“…The stress strain curves obtained from microindentation testes, conducted at different depth of bioprinted hydrogel constructs, demonstrated a height-dependent elastic modulus (Figure 1G). This could be attributed to the inherent nonuniformity associated with the DLP (stereolithography) bioprinting technique [39][40][41] that was employed to create these constructs. In such DLP/SLA methods, different layers of the solidified material are crosslinked for different durations, which could in turn result in varying stiffness/modulus along the printing axis.…”

Computer vision-aided bioprinting for bone research

“…The main factors affecting cell viability and differentiation can be mainly divided into three groups, i.e., cell variety, printing environment, 90 , 91 and external parameters, 92 – 94 as shown in Fig. 5a .…”

Guest-host supramolecular assembly of injectable hydrogel fibers for cell encapsulation

“…We chose hMSCs for these experiments due to their multipotential for differentiation toward cell types relevant for a broad range of fibrous tissues 67 such as muscle, tendon, and ligament 68 . Protecting cells during injection and preserving high viability is one of the fundamental requirements for subsequent therapeutic application, but many injectable delivery vehicles suffer from poor cell survival 69,70 . Previous studies have addressed this issue using materials that leverage physical crosslinking since their compliant mechanical properties support non-uniform network deformation 40,63,71 .…”

“…One possible explanation for the fibrous materials' successful protection of cells during injection, despite the more robust bulk mechanical stiffnesses compared to other successful cell carrier materials, is the stochastic nature of self-assembling fiber hierarchical structures allowing microstructural deformation mechanisms such as shear attenuation via fiber sliding [73][74][75] . Local shear attenuation is important for native tissue mechanical function and may be mimicked by the supramolecular interactions between complementary guest and host hydrogel fibers, leading to increased force dissipation and thereby protecting encapsulated cells from extensional flow at the entrance of the syringe needle and the subsequent disruption of the cellular membrane 8,69,70 .…”