Engineering Anisotropic Biomimetic FibrocartilageMicroenvironment by Bioprinting Mesenchymal Stem Cells in NanoliterGel Droplets

摘要

Over the past decade, bioprinting has emerged as a promising patterning strategy to organize cells and extracellular components both in two and three dimensions (2D and 3D) to engineer functional tissue mimicking constructs. So far, tissue printing has neither been used for 3D patterning of mesenchymal stem cells (MSCs) in multiphase growth factor embedded 3D hydrogels nor been investigated phenotypically in terms of simultaneous differentiation into different cell types within the same micropatterned 3D tissue constructs. Accordingly, we demonstrated a biochemical gradient by bioprinting nanoliter droplets encapsulating human MSCs, bone morphogenetic protein 2 (BMP-2), and transforming growth factor β1 (TGF- β1), engineering an anisotropic biomimetic fibrocartilage microenvironment. Assessment of the model tissue construct displayed multiphasic anisotropy of the incorporated biochemical factors after patterning. Quantitative real time polymerase chain reaction (qRT-PCR) results suggested genomic expression patterns leading to simultaneous differentiation of MSC populations into osteogenic and chondrogenic phenotype within themultiphasic construct, evidenced by upregulation of osteogenesis andcondrogenesis related genes during in vitro culture.Comprehensive phenotypic network and pathway analysis results, whichwere based on genomic expression data, indicated activation of differentiationrelated mechanisms, via signaling pathways, including TGF, BMP, andvascular endothelial growth factor.