A multicellular bioprinted cell construct for vascularized bone tissue regeneration

In the present study, a bioprinted cell-laden construct consisting of collagen, β-tricalcium phosphate, and two different cell types, human adipose stem cells (hASCs) and human umbilical vein endothelial cells (HUVECs), was prepared for bone tissue regeneration in spinal fusion. By using the appropriate printing parameters and bioceramic/cell compositions in the bioink, a 3D cell-laden construct consisting of microscale struts was successfully generated. To evaluate the contribution of the laden stem cells and endothelial cells in promoting angiogenic and osteogenic activities, differentiation of the cells within the bioink was analyzed by measuring gene expression profiles and immunofluorescence imaging. The hASC/HUVEC-laden structure exhibited a strong angiogenic phenotype and upregulated angiogenic factors, as well as enhanced expression of osteogenic gene markers due to the synergistic crosstalk of the two cell types. The construct laden with hASCs/HUVECs was implanted in a mouse model of posterolateral lumbar spinal fusion, and the structure provided significantly higher new bone formation and angiogenesis compared with constructs laden with only hASCs. The in vitro and in vivo findings suggest that biomimetic cell-laden constructs could perform as potential bone tissue regenerating structures to encourage effective spinal fusion.