3D Bioprinting a Cell-Laden Bone Matrix for Breast Cancer Metastasis Study.

Metastasis is one of the deadliest consequences of breast cancer, with bone being one of the primary sites of occurrence. Insufficient 3D biomimetic models currently exist to replicate this process in vitro. In this study, we developed a biomimetic bone matrix using 3D bioprinting technology to investigate the interaction between breast cancer (BrCa) cells and bone stromal cells (fetal osteoblasts and human bone marrow mesenchymal stem cells (MSCs)). A tabletop stereolithography 3D bioprinter was employed to fabricate a series of bone matrices consisting of osteoblasts or MSCs encapsulated in gelatin methacrylate (GelMA) hydrogel with nanocrystalline hydroxyapatite (nHA). When BrCa cells were introduced into the stromal cell-laden bioprinted matrices, we found that the growth of BrCa cells was enhanced by the presence of osteoblasts or MSCs, whereas the proliferation of the osteoblasts or MSCs was inhibited by the BrCa cells. The BrCa cells co-cultured with MSCs or osteoblasts presented increased vascular endothelial growth factor (VEGF) secretion in comparison to that of monocultured BrCa cells. Additionally, the alkaline phosphatase activity of MSCs or osteoblasts was reduced after BrCa cell co-culture. These results demonstrate that the 3D bioprinted matrix, with BrCa cells and bone stromal cells, provides a suitable model with which to study the interactive effects of cells in the context of an artificial bone microenvironment and thus may serve as a valuable tool for the investigation of postmetastatic breast cancer progression in bone.