||Yuji Nashimoto, Tomoya Hayashi, Itsuki Kunita, Akiko Nakamasu, Yu-Suke Torisawa, Masamune Nakayama, Hisako Takigawa-Imamura, Hidetoshi Kotera, Koichi Nishiyama, Takashi Miura, Ryuji Yokokawa, Integrating perfusable vascular networks with a three-dimensional tissue in a microfluidic device., Integrative biology : quantitative biosciences from nano to macro, 10.1039/c7ib00024c, 9, 6, 506-518, 2017.06, Creating vascular networks in tissues is crucial for tissue engineering. Although recent studies have demonstrated the formation of vessel-like structures in a tissue model, long-term culture is still challenging due to the lack of active perfusion in vascular networks. Here, we present a method to create a three-dimensional cellular spheroid with a perfusable vascular network in a microfluidic device. By the definition of the cellular interaction between human lung fibroblasts (hLFs) in a spheroid and human umbilical vein endothelial cells (HUVECs) in microchannels, angiogenic sprouts were induced from microchannels toward the spheroid; the sprouts reached the vessel-like structures in a spheroid to form a continuous lumen. We demonstrated that the vascular network could administer biological substances to the interior of the spheroid. As cell density in the spheroid is similar to that of a tissue, the perfusable vasculature model opens up new possibilities for a long-term tissue culture in vitro..
||Takumi Higaki, Natsumaro Kutsuna, Kae Akita, Hisako Takigawa-Imamura, Kenji Yoshimura, Takashi Miura, A Theoretical Model of Jigsaw-Puzzle Pattern Formation by Plant Leaf Epidermal Cells, PLOS COMPUTATIONAL BIOLOGY, 10.1371/journal.pcbi.1004833, 12, 4, e1004833, 2016.04, Plant leaf epidermal cells exhibit a jigsaw puzzle-like pattern that is generated by interdigitation of the cell wall during leaf development. The contribution of two ROP GTPases, ROP2 and ROP6, to the cytoskeletal dynamics that regulate epidermal cell wall interdigitation has already been examined; however, how interactions between these molecules result in pattern formation remains to be elucidated. Here, we propose a simple interface equation model that incorporates both the cell wall remodeling activity of ROP GTPases and the diffusible signaling molecules by which they are regulated. This model successfully reproduces pattern formation observed in vivo, and explains the counterintuitive experimental results of decreased cellulose production and increased thickness. Our model also reproduces the dynamics of three-way cell wall junctions. Therefore, this model provides a possible mechanism for cell wall interdigitation formation in vivo..
||Miura, T., Hartmann, D., Kinboshi, M., Komada, M., Ishibashi, M., Shiota, K., The cyst-branch difference in developing chick lung results from a different morphogen diffusion coefficient, Mechanisms of Development, 10.1016/j.mod.2008.11.006, 126, 3-4, 160-172, 2009.04, The developing avian lung is formed mainly by branching morphogenesis, but there is also a unique cystic structure, the air sac, in the ventral region. It has been shown that mesenchymal tissue is responsible for the differential development of a cystic or branched structure, and that the transcription factor Hoxb may be involved in determining this regional difference. We have previously developed two scenarios for branch-cyst transition, both experimentally and theoretically: increased production or increased diffusion of FGF. The aim of the present study was to discover whether one of these scenarios actually operates in the ventral region of the chick lung. We found that the FGF10 level was lower while the diffusion of FGF10 was more rapid in the ventral lung, indicating that the second scenario is more plausible. There are two possibilities as to why the diffusion of FGF10 differs between the two regions: (1) diffusion is facilitated by the looser tissue organisation of the ventral lung mesenchyme; (2) stronger expression of heparan sulphate proteoglycan ( HSPG) in the dorsal lung traps FGF and decreases the effective diffusion coefficient. Mathematical analysis showed that the dorsal-ventral difference in the amount of HSPG is not sufficient to generate the observed difference in pattern, indicating that both extracellular matrix and tissue architecture play a role in this system. These results suggest that the regional cystic-branched difference within the developing chick lung results from a difference in the rate of diffusion of morphogen between the ventral and dorsal regions due to differential levels of HSPG and a different mesenchymal structure. (C) 2008 Elsevier Ireland Ltd. All rights reserved..
||Takashi Miura, Kohei Shiota, TGFβ2 acts as an 'activator' molecule in reaction-diffusion model and is involved in cell sorting phenomenon in mouse limb micromass culture, Developmental Dynamics, 10.1002/(SICI)1097-0177(200003)217:3<241::AID-DVDY2>3.0.CO;2-K, 217, 3, 241-249, 2000.04, It was previously speculated that TGFβ acts as an 'activator'-molecule in chondrogenic pattern formation in the limb micromass culture system, but its precise role and relationship with the cell sorting phenomenon have not been properly studied. In the present study, we examined whether the TGFβ2 molecule satisfies the necessary conditions for an 'activator'-molecule in the reaction-diffusion model. Firstly, we showed that TGFβ2 became localized at chondrogenic sites during the establishment of a chondrogenic pattern, and exogenous TGFβ2 promoted chondrogenesis when added in the culture medium. Secondly, TGFβ2 protein was shown to promote the production of its own mRNA after 3 hr, indicating that a positive feedback mechanism exists which may be responsible for the emergence of the chondrogenic pattern. We then found that when locally applied with beads, TGFβ2 suppressed chondrogenesis around the beads, indicating it induces the lateral inhibitory mechanism, which is a key element for the formation of the periodic pattern. We also examined the possible effects of TGFβ2 on the cell sorting phenomenon and found that TGFβ2 exerts differential chemotactic activity on proximal and distal mesenchyme cells of the limb bud, and at very early phases of differentiation TGFβ2 promotes the expression of N-cadherin protein which is known to be involved in pattern formation in this culture system. These findings suggest that TGFβ2 acts as an 'activator'-like molecule in chondrogenic pattern formation in vitro, and is possibly responsible for the cell sorting phenomenon. (C) 2000 Wiley- Liss, Inc..