Development of Surgical and Visualization Procedures to Analyze Vasculatures by Mouse Tail Edema Model.

BACKGROUND: Because of the high frequency of chronic edema formation in the current "aged" society, analyses and detailed observation of post-surgical edema are getting more required. Post-surgical examination of the dynamic vasculature including L.V. (Lymphatic Vasculature) to monitor edema formation has not been efficiently performed. Hence, procedures for investigating such vasculature are essential. By inserting transparent sheet into the cutaneous layer of mouse tails as a novel surgery model (the Tail Edema by Silicone sheet mediated Transparency protocol; TEST), the novel procedures are introduced and analyzed by series of histological analyses including video-based L.V. observation and 3D histological reconstruction of vasculatures in mouse tails. RESULTS: The dynamic generation of post-surgical main and fine (neo) L.V. connective structure during the edematous recovery process was visualized by series of studies with a novel surgery model. Snapshot images taken from live binocular image recording for TEST samples suggested the presence of main and elongating fine (neo) L.V. structure. After the ligation of L.V., the enlargement of main L.V. was confirmed. In the case of light sheet fluorescence microscopy (LSFM) observation, such L.V. connections were also suggested by using transparent 3D samples. Finally, the generation of neo blood vessels particularly in the region adjacent to the silicone sheet and the operated boundary region was suggested in 3D reconstruction images. However, direct detection of elongating fine (neo) L.V. was not suitable for analysis by such LSFM and 3D reconstruction procedures. Thus, such methods utilizing fixed tissues are appropriate for general observation for the operated region including of L.V. CONCLUSIONS: The current surgical procedures and analysis on the post-surgical status are the first case to observe vasculatures in vivo with a transparent sheet. Systematic analyses including the FITC-dextran mediated snap shot images observation suggest the elongation of fine (neo) lymphatic vasculature. Post-surgical analyses including LSFM and 3D histological structural reconstruction, are suitable to reveal the fixed structures of blood and lymphatic vessels formation.

In vivo feasibility test using transparent carbon nanotube-coated polydimethylsiloxane sheet at brain tissue and sciatic nerve.

Carbon nanotubes, with their unique and outstanding properties, such as strong mechanical strength and high electrical conductivity, have become very popular for the repair of tissues, particularly for those requiring electrical stimuli. Polydimethylsiloxane (PDMS)-based elastomers have been used in a wide range of biomedical applications because of their optical transparency, physiological inertness, blood compatibility, non-toxicity, and gas permeability. In present study, most of artificial nerve guidance conduits (ANGCs) are not transparent. It is hard to confirm the position of two stumps of damaged nerve during nerve surgery and the conduits must be cut open again to observe regenerative nerves after surgery. Thus, a novel preparation method was utilized to produce a transparent sheet using PDMS and multiwalled carbon nanotubes (MWNTs) via printing transfer method. Characterization of the PDMS/MWNT (PM) sheets revealed their unique physicochemical properties, such as superior mechanical strength, a certain degree of electrical conductivity, and high transparency. Characterization of the in vitro and in vivo usability was evaluated. PM sheets showed high biocompatibility and adhesive ability. In vivo feasibility tests of rat brain tissue and sciatic nerve revealed the high transparency of PM sheets, suggesting that it can be used in the further development of ANGCs. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1736-1745, 2017.

A transparent silica colloidal crystal/PDMS composite and its application for crack suppression of metallic coatings.

A silica colloidal crystal (SCC)-polydimethylsiloxane (PDMS) composite with a heterogeneous surface of silica and PDMS was prepared by spreading a premixed PDMS solution on the 3D structured SCCs and curing the solution in-situ. Although the SCCs had a light blue color, the obtained composite of SCC and PDMS, due to the close effective refractive indexes of the materials, was colorless and transparent; the UV-vis spectra indicated a negligible effect of the added SCC on the transmittance of the PDMS sheet (1% reduction). Interestingly, the transparent composite sheet became translucent under stress and became clear again when relaxed. It was found that the wrinkles formed on the surface under stress were responsible for the optical change; and, the formation of the wrinkles was ascribed to the rigid nature of the SCC layer embedded in PDMS. We had applied this SCC/PDMS composite as a substrate to support a thin gold film of nanoscale thickness and found that the embedded SCC layer worked well as a transitional interface for bonding materials of mismatched mechanical properties. The incorporation of SCC layer significantly suppressed the crack generation and propagation of the gold film. The results demonstrated a potential approach for fabricating compliant and crackfree metallic films on polymeric substrates.