Bioprinted integrated gradient biomechanical signal-tailored osteosarcoma model: advancing insights into tumor development and drug screening

In the current settings of osteosarcoma research and drug screening, in vitro three-dimensional (3D) models, which overcome the limitations of traditional models, are favored. In in vitro 3D models, tumor microenvironment simulation, particularly of the mechanical microenvironment, is crucial for estimating the biological effects of a tumor. However, current in vitro osteosarcoma model construction is often limited to a single mechanical signal, which fails to simulate the diversity of osteosarcoma mechanical stimuli. In this study, we utilized embedded bioprinting technology and the multiple response properties of calcium ions in soft and hard stiffness systems with osteosarcoma cell biological functions to construct an integrated gradient biomechanical signal-tailored osteosarcoma model (IGBSTOM). We achieved this by printing a fibrinogen bioink containing calcium ions and osteosarcoma tumor spheroids within an extracellular matrix composed of methacryloylated alginate, methacryloylated gelatin, thrombin, and transglutaminase, which is rich in polysaccharides and proteins and exhibits self-healing properties. Our in vitro and in vivo studies showed that the IGBSTOM enhanced tumor stemness, proliferation, and migration, and successfully reproduced the nest-like structure of tumors, providing an in vitro research platform that is more similar to the natural tumor than the existing models. This study proposes a novel IGBSTOM construction and provides a new strategy for the clinical understanding of tumor development, drug screening, and exploration of drug resistance and metastasis mechanisms.