Metre-long cell-laden microfibres exhibit tissue morphologies and functions.

Artificial reconstruction of fibre-shaped cellular constructs could greatly contribute to tissue assembly in vitro. Here we show that, by using a microfluidic device with double-coaxial laminar flow, metre-long core-shell hydrogel microfibres encapsulating ECM proteins and differentiated cells or somatic stem cells can be fabricated, and that the microfibres reconstitute intrinsic morphologies and functions of living tissues. We also show that these functional fibres can be assembled, by weaving and reeling, into macroscopic cellular structures with various spatial patterns. Moreover, fibres encapsulating primary pancreatic islet cells and transplanted through a microcatheter into the subrenal capsular space of diabetic mice normalized blood glucose concentrations for about two weeks. These microfibres may find use as templates for the reconstruction of fibre-shaped functional tissues that mimic muscle fibres, blood vessels or nerve networks in vivo.

Optimizing the diameter of holes for flexible regeneration microelectrode.

In this study, we suggest a new guideline for regeneration microelectrode to be implanted between the severed stumps of peripheral nerves, the microelectrode designed particularly for connecting the signal line of an artificial hand directly to the nerve system. The nerve regeneration microelectrode is an interface device expected to realize a BMI (brain-machine interface).

Biomolecular-motor-based autonomous delivery of lipid vesicles as nano- or microscale reactors on a chip.

We aimed to create an autonomous on-chip system that performs targeted delivery of lipid vesicles (liposomes) as nano- or microscale reactors using machinery from biological systems. Reactor-liposomes would be ideal model cargoes to realize biomolecular-motor-based biochemical analysis chips; however, there are no existing systems that enable targeted delivery of cargo-liposomes in an autonomous manner. By exploiting biomolecular-motor-based motility and DNA hybridization, we demonstrate that single-stranded DNA (ssDNA)-labeled microtubules (MTs), gliding on kinesin-coated surfaces, acted as cargo transporters and that ssDNA-labeled cargo-liposomes were loaded/unloaded onto/from gliding MTs without bursting at loading reservoirs/micropatterned unloading sites specified by DNA base sequences. Our results contribute to the development of an alternative strategy to pressure-driven or electrokinetic flow-based microfluidic devices.

Biomolecular-motor-based nano- or microscale particle translocations on DNA microarrays.

We aimed to create autonomous on-chip systems that perform targeted translocations of nano- or microscale particles in parallel using machinery that mimics biological systems. By exploiting biomolecular-motor-based motility and DNA hybridization, we demonstrate that single-stranded DNA-labeled microtubules gliding on kinesin-coated surfaces acted as cargo translocators and that single-stranded DNA-labeled cargoes were loaded/unloaded onto/from gliding microtubules at micropatterned loading/unloading sites specified by DNA base sequences. Our results will help to create autonomous molecular sorters and sensors.

Near-UV radiation promotes growth of Chlorella.

The wavelength of natural sunlight reaching the Earth's surface was detected to be above 300 nm using a multichannel spectrodetector and the ratio of UV to photosynthetically active radiation (PAR) of sunlight in Japan (137 degrees E/35 degrees 11' N, altitude; 50 m) in early summer was estimated to be 0.07:1 (i.e., 7%). On the basis of this UV/PAR ratio, Chlorella ellipsoidea (IAM-27) cells were cultured in flasks under various conditions of UV irradiation in growth chambers. The growth (cell division) of these cells without near-UV radiation was inferior to that with near-UV radiation. Growth at a UV/PAR ratio of 7% (natural conditions), determined tentatively using our detector in the present study, was maximal similar to those at 14% and 28%; whereas that at 0.7% was somewhat less and that at 70% was considerably less. Growth was linked with the activities of stress enzymes. NAD(P)H-dependent oxidase [NAD(P)-DH] and xanthine oxidase (XOD), extracted from Chlorella exposed to near-UV radiation demonstrated lower activities than those from Chlorella not exposed to near-UV radiation. On the other hand, superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APOD) extracted from Chlorella exposed to near-UV radiation have higher activities than those from unexposed Chlorella. Near-UV radiation clearly acted as an important factor for growth (cell division), at least at UV/PAR ratios of up to 0.28:1.

Regulation of ethylene-forming system in Chlorella by near-UV radiation.

The growth (cell division) of Chlorella cells cultured under photosynthetically active radiation (PAR) without near-UV radiation was inferior to that under PAR with near-UV radiation. To elucidate this phenomenon, the relationship between near-UV radiation and ethylene production in Chlorella cells was examined. The suppression of ethylene production by UV radiation suggests that this phenomenon is associated with the production of ethylene. Chlorella (a eukaryotic protista) was found to produce ethylene from methionine via S-adenosyl-methionine (SAM) and 1-aminocyclo-propane-1-carboxylate (ACC) as in higher plants, and the activity of ACC oxidase, a limiting factor of ethylene production, appears to be associated with the growth of Chlorella. A possible mechanism for the action of near-UV radiation on ethylene biosynthesis and growth suppression by ethylene is discussed.