Using Laser Tweezers For Manipulating Isolated Neurons In Vitro
Summary
This video describes the manipulation of cultured neurons using laser tweezers in vitro.
Abstract
In this paper and video, we describe the protocols used in our laboratory to study the targeting preferences of regenerating cell processes of adult retinal neurons in vitro. Procedures for preparing retinal cell cultures start with the dissection, digestion and trituration of the retina, and end with the plating of isolated retinal cells on dishes made especially for use with laser tweezers. These dishes are divided into a cell adhesive half and a cell repellant half. The cell adhesive side is coated with a layer of Sal-1 antibodies, which provide a substrate upon which our cells grow. Other adhesive substrates could be used for other cell types. The cell repellant side is coated with a thin layer of poly-HEMA. The cells plated on the poly-HEMA side of the dish are trapped with the laser tweezers, transported and then placed adjacent to a cell on the Sal-1 side to create a pair. Formation of cell groups of any size should be possible with this technique. “Laser-tweezers-controlled micromanipulation” means that the investigator can choose which cells to move, and the desired distance between the cells can be standardized. Because the laser beam goes through transparent surfaces of the culture dish, cell selection and placement are done in an enclosed, sterile environment. Cells can be monitored by video time-lapse and used with any cell biological technique required. This technique may help investigations of cell-cell interactions.
Protocol
Discussion
Light has momentum, and when a light ray is refracted as it passes through a cell, a force is required to change the direction of the momentum. Because of the law of conservation of momentum, a force in the opposite direction must, in turn, react back on a cell. Ashkin (1991) showed that the force generated by a laser beam focused by a microscope objective lens will move a cell toward the center of focus. Even though a laser beam generates only a few piconewtons of force, this force is sufficient to pull a cell through m…
Acknowledgements
Research was supported by NIH Grants EY012031 and EY0182175 and the F.M. Kirby Foundation.
Materials
| Material Name | Type | Company | Catalogue Number | Comment |
|---|---|---|---|---|
| 25mm circle No.1 coverglass | VWR Scientific Inc., Westchester, PA | 48380 080 | ||
| poly-2-hydroxyethylmethacrylate (poly-HEMA) | Sigma Chemical Co., St Louis, MO | P-3932 | Dissolve in 95% ethanol | |
| Goat anti-mouse IgG antibody | Chemicon International, Temecula CA | AP181 | 1mg in 1ml, dilute 10x for use | |
| Sal-1 supernatant containing mouse anti-salamander antibody | generously provided by Dr. Peter MacLeish | Dr. Peter MacLeish, Morehouse School of Medicine, Atlanta, GA | ||
| 3 mm bore 5ml pyrex disposable pipets | Corning Inc., Corning NY | 7078A-5 | ||
| Cell culture dishes 35mm x 10mm | Corning inc., Corning NY | 430165 | ||
| Sylgard 184 silicone elastomer kit | Dow Corning Corp., Midland MI | |||
| Optical tweezers-microtool or laser tweezers | Cell Robotics Inc., Albuquerque NM | |||
| 1 W continuous wave diode laser of 980nm wavelength | Cell Robotics Inc., Albuquerque NM | |||
| Axiovert 100 inverted light microscope | Carl Zeiss Inc., Thornwood, NY | |||
| 40x oil immersion plan neofluor objective lens | Carl Zeiss Inc., Thornwood, NY | Numerical aperture (N.A. 1.3) | ||
| Black and white CCD camera | Sony Corporation, Tokyo, Japan | |||
| Computer and joystick with software | Cell Robotics Inc. | for controlling a motorized stage |
References
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