Observação do movimento ciliar de células epiteliais do plexo coróide<em> Ex Vivo</em
Summary
In this study, a detailed light microscopic technique was optimized for real-time observation and analysis of the motion of CPEC cilia ex vivo together with an electron microscopic method for ultrastructural analysis.
Abstract
The choroid plexus is located in the ventricular wall of the brain, the main function of which is believed to be production of cerebrospinal fluid. Choroid plexus epithelial cells (CPECs) covering the surface of choroid plexus tissue harbor multiple unique cilia, but most of the functions of these cilia remain to be investigated. To uncover the function of CPEC cilia with particular reference to their motility, an ex vivo observation system was developed to monitor ciliary motility during embryonic, perinatal and postnatal periods. The choroid plexus was dissected out of the brain ventricle and observed under a video-enhanced contrast microscope equipped with differential interference contrast optics. Under this condition, a simple and quantitative method was developed to analyze the motile profiles of CPEC cilia for several hours ex vivo. Next, the morphological changes of cilia during development were observed by scanning electron microscopy to elucidate the relationship between the morphological maturity of cilia and motility. Interestingly, this method could delineate changes in the number and length of cilia, which peaked at postnatal day (P) 2, while the beating frequency reached a maximum at P10, followed by abrupt cessation at P14. These techniques will enable elucidation of the functions of cilia in various tissues. While related techniques have been published in a previous report1, the current study focuses on detailed techniques to observe the motility and morphology of CPEC cilia ex vivo.
Introduction
Cilia are hair-like projections on the surface of most vertebrate cells, which have attracted attention by medical researchers because of a class of diseases termed ciliopathies2–4. Despite the ubiquitous expression of the organelle, a wide variety of ciliary functions have been reported, including motility and biosensing. For example, motile cilia on the mucoepithelial surface transport mucus5 and epithelial debris to the outlet of tracts, thereby preventing disease by clearing the surface of epithelia. Moreover, during early developmental periods and embryonic stages, cilia regulate the proliferation of stem cells6, and are involved in the determination of left–right asymmetry of the vertebrate body7.
Choroid plexus epithelial cells (CPECs) are derivatives of neuroepithelial cells that cover the surface of the choroid plexus tissue in the brain, which play important roles in maintaining homeostasis of the intracranial environment by production of cerebrospinal fluid (CSF). It has been previously demonstrated that CPECs have multiple non-motile cilia that regulate the production of CSF through G-protein-coupled receptors that are specifically concentrated on the cilia8. Although these cilia had been regarded as quiescent non-motile cilia, it was discovered that some CPEC cilia exhibit transient motility during the neonatal period1. This finding was quite important because it revealed that so-called non-motile cilia are not necessarily immotile from the beginning of development and might display transient motility during specific time windows, possibly in response to specific physiological demands and functions9. To precisely describe the motile nature of CPEC cilia, it is necessary to develop an ex vivo observation system that encompasses analysis of the kinetic profiles unique to CPEC cilia.
With respect to motility, although several technical reports have described observations of the motile cilia of the tracheal epithelium5,10, motile single-cell flagella11, so-called conventional motile cilia12, and nodal cilia13, detailed analytical methods applicable to relatively undulated structures such as the choroid plexus have not been well documented so far. Moreover, a high time resolution is required to analyze the ciliary movement of CPECs, in which expensive high-speed cameras are indispensable. To circumvent this necessity and simplify monitoring the ciliary motility of various cell types, a low cost, high-speed camera has been introduced, and an easily accessible and convenient method to record the motility of motile cilia, especially to describe the speed and pattern of motion of each cilium, has been developed1. Moreover, original image analysis software “TI Workbench” has been used here to facilitate detailed analysis of motility. Collectively, this method provides a new concise strategy to analyze ciliary motion together with correlative scanning electron microscopy (SEM), which can be adopted in a wide range of cilium research.
Protocol
Representative Results
Discussion
Perspectivas deste método
Embora a técnica aqui descrita não proporciona uma análise mais detalhada dos cílios do que os métodos previamente publicados, o significado desta técnica reside na simplicidade do sistema e relação custo-eficácia, que pode ser facilmente aplicado a qualquer tipo de rastreio de motilidade ciliar ex vivo. Em particular, TI Workbench fornece uma interface simples e fácil de usar que permite aos pesquisadores observar e analisar a motilidade ciliar …
Divulgations
The authors have nothing to disclose.
Acknowledgements
This work was supported by a Project for Private Universities: matching fund subsidy from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan (T.I.) and Grants-in-Aid for Scientific Research (C) from MEXT (S.T. and K.N).
Materials
| for both live imaging and SEM preparation | |||
| stereo microscope | Olympus | SZX7 | |
| flat paper towel | |||
| Φ10-cm plastic dish | |||
| 100-mL beaker | |||
| straight operating scissors | Sansyo | S-2B | |
| watchmaker forceps | Dumont | No.DU-3 or -4, INOX | |
| for live cell imaging | |||
| glass bottom dish | Matsunami Glass | D110300 | |
| for SEM preparation | |||
| alminum foil | |||
| 5-mL glass vial with a polyethylene cap | Nichiden Rika-Glass | PS-5A | |
| transfer pipette | Samco Scientific | SM251-1S | for specimen tranfer |
| toothpick | for specimen transfer | ||
| ion sputter with gold-palladium | Hitachi | E-1030 | |
| critical point dryer | Hitachi | HCP-2 | |
| for live cell imaging | |||
| inverted microscope | Olympus | IX81 | |
| 100 W mercury lump housing and power supply | Olympus | U-ULH and BH2-RFL-T3 | |
| 100 W mercury lamp | Ushio | USH103D | |
| DIC condenser, n.a. 0.55 | Olympus | IX-LWUCD | |
| electrrical shutter | Vincent Associates | VS35S22M1R3-24 and VMM-D1 | manual shutter can be used. |
| band-pass filter (400-700 nm, Φ45 mm) | Koshin Kagaku | C10-110621-1 | |
| ND filter (Φ45 mm) | Olympus | 45ND6, 45ND25 | combination of 25% and 6% ND filters are used |
| objective lens (water immersion) with DIC element | Olympus | UApo 40XW/340, n.a., 1.15 with IX-DPAO40 | |
| high-speed video camera | Allied Vision Technologies | GE680 | >= 200 Hz frame rate and 1 msec expose time |
| image acquisition / analysis software | in-hous software | TI Workbench | capable of acquisition at high frame rates. |
| PC for camera control / analysis | Apple | Mac Pro | |
| vibration isolation table | Meiritsu Seiki | AD0806 | |
| weight for tissue | Warner Instruments | slice anchor kits | It can be made with nylon mesh glued to a U-shape squashed Φ0.5mm platinum wire. |
| for SEM | |||
| inverted microscope | Olympus | IX81 | |
| scanning electron microscope | JEOL | JSM-6510 | |
| for live cell imaging | |||
| ethanol | Wako Chemicals | 057-00456 | |
| Leibovitz L-15 medium | Life Technologies | 11415-064 | |
| for SEM preparation | |||
| ethanol | Wako Chemicals | 057-00456 | |
| Hank's balanced salt solution | Life Technologies | 14170112 | |
| paraformaldehyde | Merck | 1040051000 | |
| glutaraldehyde | Nacalai tesque | 17003-05 | |
| isoamyl acetate | Nacalai tesque | 02710-95 | |
| Molecular Sieves 4A 1/8 | Wako Chemicals | 130-08655 | for preparation of anhydrous ethanol |
| phosphate buffer saline (PBS) | Sigma-Aldrich | D1408 | |
| phosphate buffer, 0.1 M | To make 100 ml, mix 19.0 ml of 0.1 M NaH2PO4 and 81.0 ml of 0.1 M Na2HPO4 | ||
| monosodium phosphate (dihydrate) | Nacalai tesque | 31718-15 | |
| disodium phosphate (anhydrous) | Nacalai tesque | 31801-05 | |
| suclose | Nacalai tesque | 30406-25 | |
| osmium tetroxide | Nisshin EM | 300 | |
| dry ice |
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