This paper describes
a biohybrid actuator consisting of a microgrooved
thin film, powered by contractile, aligned skeletal muscle cells.
The system was made of a thermoplastic elastomer [SBS, poly(styrene-block-butadiene-block-styrene)]. We prepared
SBS thin films with different thicknesses (0.5–11.7 μm)
and Young’s moduli (46.7–68.6 MPa) to vary their flexural
rigidity. The microgrooves on the SBS thin film resembled the microstructure
of the extracellular matrix of muscle and facilitated the alignment
and differentiation of skeletal muscle cells. Electrical stimulation
was applied to self-standing biohybrid thin films to trigger their
contraction, enabled by the low flexural rigidity of the SBS thin
film. Finite element model simulations were also examined to predict
their contractile behavior. We achieved the prediction of displacements,
which were rather close to the actual values of the SBS thin film:
the discrepancy was <5% on the X axis. These results
pave the way for in silico prediction of the contractile
capabilities of elastomeric thin films. This study highlights the
potential of microgrooved SBS thin films as ultraflexible platforms
for biohybrid machines.
We investigated a porous nanosheet to induce the formation of spheroids consisting of adipose-tissue derived stem cells, which is useful not only for engineering 3D cellular organization, but also for imaging the detailed structure of the spheroid.
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The short survival time of transplanted adipose-derived mesenchymal stem cells (ASCs) is a problem for skin wound healing. Transplantation after the formation of cellular spheroids has been investigated as a promising method for prolonging cellular survival. However, there have been technical restrictions for transplantation of spheroids in clinical practice. Here, we show an effective method for transplantation of ASC spheroids onto skin wounds in order to efficiently cure refractory ulcers. To assist anchoring of spheroids onto skin wounds, we used a 120-nm-thick free-standing film (nanosheet) that has a highly adhesive property. Bioluminescence imaging showed that ASC spheroids carried by the nanosheet survived for 14 days, which is about two-times longer than that previously reported. Wounds treated with a nanosheet carrying ASC spheroids were 4-times smaller than untreated wounds on day 14. This method for transplantation of spheroids could be applied to cell therapy for various refractory skin wounds.
Synthetic biodegradable polymers including poly(lactic acid) (PLA) are attractive cell culture substrates because their surfaces can be micropatterned to support cell adhesion. The cell adhesion properties of a scaffold mainly depend on its surface chemical and structural features; however, it remains unclear how these characteristics affect the growth and differentiation of cultured cells or their gene expression. In this study, we fabricated two differently structured PLA nanosheets: flat and microgrooved. We assessed the growth and differentiation of mouse primary cultured cortical neurons on these two types of nanosheets after pre-coating with poly-D-lysine and vitronectin. Interestingly, prominent neurite bundles were formed along the grooves on the microgrooved nanosheets, whereas thin and randomly extended neurites were only observed on the flat nanosheets. Comparative RNA sequencing analyses revealed that the expression of genes related to postsynaptic density, dendritic shafts, and asymmetric synapses was significantly and consistently up-regulated in cells cultured on the microgrooved nanosheets when compared with those cultured on the flat nanosheets. These results indicate that microgrooved PLA nanosheets can provide a powerful means of establishing a culture system for the efficient and reproducible differentiation of neurons, which will facilitate future investigations of the molecular mechanisms underlying the pathogenesis of neurological disorders. Dissociated primary neuronal cultures are widely used not only for basic neuroscience research but also for drug discovery for neurological disorders 1-3. In such culture systems, scaffolds are one of the key factors providing the cells with structural support for attachment and subsequent growth and differentiation. Thus far, numerous synthetic polymers including polystyrene, poly(lactic acid) (PLA), poly(glycolic acid), and poly(lactic-co-glycolic acid) 4-6 have been developed to serve as scaffolds. Among these, PLA, a biodegradable and resorbable polyester, has recently come into the limelight for its utility in medical applications such as tissue regeneration 7. Polymeric ultrathin film consisting of PLA, hereinafter called "PLA nanosheet," is a thin, soft, and flexible material, with properties that allow it to adhere anywhere without any adhesive materials 8. Many studies have demonstrated that nanosheets can be used to dress wounds to avoid suture, prevent infection, promote bone regeneration, etc. for biomedical applications 8-13. Nanosheets are also suitable for use as a sheet substrate in cell
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