title: Fabrication of viable centimeter-sized 3D tissue constructs with microchannel conduits for improved tissue properties through assembly of cell-laden microbeads.
abstract: Bottom-up approaches have emerged as a new philosophy in tissue engineering, enabling precise control over tissue morphogenesis at the cellular level. We previously prepared large bone-like tissues using cell-laden microbeads (microtissues) by following a modular approach to ensure cell viability. However, a long-term culture of such avascular macroscopic tissues (macrotissues) has not been evaluated. In the present study, microtissues were fabricated by cultivating human fibroblasts on Cytopore-2 microbeads in spinner flasks for 16 days. We then examined the long-term perfusion culture for macrotissues. Specifically, following assembly in a perfusion chamber for 15 days, cell death was found to be prominent at a depth of 500 µm from the surface of macrotissues towards the interior, suggesting that there was a new mass transfer limit leading to cell death instead of tissue maturation. Subsequently, we developed a strategy by incorporating microchannel structures in centimeter-sized tissue constructs to promote mass transport. By installing glass rods (1 mm diameter, 1 mm wall-to-wall spacing) in the perfusion chamber, stable microchannel architectures were introduced during the microtissue assembly process. Based on live/dead assay and scanning electron microscopy (SEM), these channelled macrotissues (length × diameter, 1.6 × 2.0 cm) demonstrated high cell viability and compact packing of microbeads. Comparative biochemical analysis further suggested a more homogeneous spatial distribution of cells and extracellular matrix (ECM) in the channelled macrotissues than in solid ones. Viable 3D large tissues can therefore be prepared by assembling cell-laden microbeads in conjunction with microchannel carving, meeting clinical needs in tissue repair.
authors: State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, People's Republic of China.
authors: Houyong
authors: H
authors: Luo
authors: Maiqin
authors: M
authors: Chen
authors: Xiu
authors: X
authors: Wang
authors: Yang
authors: Y
authors: Mei
authors: Zhaoyang
authors: Z
authors: Ye
authors: Yan
authors: Y
authors: Zhou
authors: Wen-Song
authors: WS
authors: Tan
mesh_terms: D005347:Fibroblasts / Q000166:cytology*; D006801:Humans; D008422:Materials Testing; D044085:Microfluidics / Q000379:methods*; D008863:Microspheres; D055616:Microtechnology; D010477:Perfusion; D046509:Tissue Culture Techniques; D023822:Tissue Engineering / Q000379:methods*; D054457:Tissue Scaffolds / Q000737:chemistry*; D014022:Tissue Survival