AUTHOR=Fan Xiaoyu , Yan Yuhan , Zhao Lianhui , Xu Xin , Dong Yiyang , Sun Wei 

TITLE=Establishment of the multi-component bone-on-a-chip: to explore therapeutic potential of DNA aptamers on endothelial cells

JOURNAL=Frontiers in Cell and Developmental Biology

VOLUME=11

YEAR=2023

URL=https://www.frontiersin.org/journals/cell-and-developmental-biology/articles/10.3389/fcell.2023.1183163

DOI=10.3389/fcell.2023.1183163

ISSN=2296-634X

ABSTRACT=<p><bold>Background:</bold> Despite great efforts to develop microvascular bone chips in previous studies, current bone chips still lacked multi-component of human-derived cells close to human bone tissue. Bone microvascular endothelial cells (BMECs) were demonstrated to be closely related to the glucocorticoid (GC)-induced osteonecrosis of the femoral head (ONFH). Tumor necrosis factor-alpha (TNF-α) aptamer has been proved to bind to its receptor and block cascade activities.</p><p><bold>Objective:</bold> There are two main objectives in this study: 1) to establish a multi-component bone-on-a-chip within the microfluidic system <italic>in vitro</italic>, 2) to explore the therapeutic potential of TNF-α aptamer on BMECs in the GC-induced ONFH model.</p><p><bold>Methods:</bold> Histological features of clinical samples were analyzed before BMECs isolation. The functional bone-on-a-chip consists of the vascular channel, stromal channel and structure channel. GC-induced ONFH model was established based on the multi-component of human-derived cells. Truncation and dimerization were performed on a previously reported DNA aptamer (VR11). BMECs apoptosis, cytoskeleton and angiogenesis status in the ONFH model were observed by the TUNEL staining and confocal microscope.</p><p><bold>Results:</bold> The multi-component of BMECs, human embryonic lung fibroblasts and hydroxyapatite were cultured within the microfluidic bone-on-a-chip. TNF-α was found up-regulated in the necrotic regions of femoral heads in clinical samples and similar results were re-confirmed in the ONFH model established in the microfluidic platform by detecting cell metabolites. Molecular docking simulations indicated that the truncated TNF-α aptamer could improve the aptamer-protein interactions. Further results from the TUNEL staining and confocal microscopy showed that the truncated aptamer could protect BMECs from apoptosis and alleviate GC-induced damages to cytoskeleton and vascularization.</p><p><bold>Conclusion:</bold> In summary, a microfluidic multi-component bone-on-a-chip was established with ‘off-chip’ analysis of cell metabolism. GC-induced ONFH model was achieved based on the platform. Our findings provided initial evidence on the possible potentials of TNF-α aptamer as a new type of TNF-α inhibitor for patients with ONFH.</p>