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Mellor NG, Chung SA, Graham ES, Day BW, Unsworth CP. Eliciting calcium transients with UV nanosecond laser stimulation in adult patient-derived glioblastoma brain cancer cells in vitro. J Neural Eng 2023; 20:066026. [PMID: 37988746 DOI: 10.1088/1741-2552/ad0e7d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 11/21/2023] [Indexed: 11/23/2023]
Abstract
Objective.Glioblastoma (GBM) is the most common and lethal type of high-grade adult brain cancer. The World Health Organization have classed GBM as an incurable disease because standard treatments have yielded little improvement with life-expectancy being 6-15 months after diagnosis. Different approaches are now crucial to discover new knowledge about GBM communication/function in order to establish alternative therapies for such an aggressive adult brain cancer. Calcium (Ca2+) is a fundamental cell molecular messenger employed in GBM being involved in a wide dynamic range of cellular processes. Understanding how the movement of Ca2+behaves and modulates activity in GBM at the single-cell level is relatively unexplored but holds the potential to yield opportunities for new therapeutic strategies and approaches for cancer treatment.Approach.In this article we establish a spatially and temporally precise method for stimulating Ca2+transients in three patient-derived GBM cell-lines (FPW1, RN1, and RKI1) such that Ca2+communication can be studied from single-cell to larger network scales. We demonstrate that this is possible by administering a single optimized ultra-violet (UV) nanosecond laser pulse to trigger GBM Ca2+transients.Main results.We determine that 1.58µJµm-2is the optimal UV nanosecond laser pulse energy density necessary to elicit a single Ca2+transient in the GBM cell-lines whilst maintaining viability, functionality, the ability to be stimulated many times in an experiment, and to trigger further Ca2+communication in a larger network of GBM cells.Significance.Using adult patient-derived mesenchymal GBM brain cancer cell-lines, the most aggressive form of GBM cancer, this work is the first of its kind as it provides a new effective modality of which to stimulate GBM cells at the single-cell level in an accurate, repeatable, and reliable manner; and is a first step toward Ca2+communication in GBM brain cancer cells and their networks being more effectively studied.
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Affiliation(s)
- Nicholas G Mellor
- Department of Engineering Science, The University of Auckland, Auckland, New Zealand
| | - Sylvia A Chung
- Adult Cancer Program, Lowy Cancer Research Centre, The University of New South Wales, Sydney, Australia
| | - E Scott Graham
- Department of Molecular Medicine and Pathology & The Centre for Brain Research, The University of Auckland, Auckland, New Zealand
| | - Bryan W Day
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Charles P Unsworth
- Department of Engineering Science, The University of Auckland, Auckland, New Zealand
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From Zygote to Blastocyst: Application of Ultrashort Lasers in the Field of Assisted Reproduction and Developmental Biology. Diagnostics (Basel) 2021; 11:diagnostics11101897. [PMID: 34679594 PMCID: PMC8534476 DOI: 10.3390/diagnostics11101897] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 10/08/2021] [Accepted: 10/11/2021] [Indexed: 11/17/2022] Open
Abstract
Although the use of lasers in medical diagnosis and therapies, as well as in fundamental biomedical research is now almost routine, advanced laser sources and new laser-based methods continue to emerge. Due to the unique ability of ultrashort laser pulses to deposit energy into a microscopic volume in the bulk of a transparent material without disrupting the surrounding tissues, the ultrashort laser-based microsurgery of cells and subcellular components within structurally complex and fragile specimens such as embryos is becoming an important tool in developmental biology and reproductive medicine. In this review, we discuss the mechanisms of ultrashort laser pulse interaction with the matter, advantages of their application for oocyte and preimplantation embryo microsurgery (e.g., for oocyte/blastomere enucleation and embryonic cell fusion), as well as for nonlinear optical microscopy for studying the dynamics of embryonic development and embryo quality assessment. Moreover, we focus on ultrashort laser-based approaches and techniques that are increasingly being applied in the fundamental research and have the potential for successful translation into the IVF (in vitro fertilization) clinics, such as laser-mediated individual embryo labelling and controlled laser-assisted hatching.
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Blázquez-Castro A, Fernández-Piqueras J, Santos J. Genetic Material Manipulation and Modification by Optical Trapping and Nanosurgery-A Perspective. Front Bioeng Biotechnol 2020; 8:580937. [PMID: 33072730 PMCID: PMC7530750 DOI: 10.3389/fbioe.2020.580937] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 09/01/2020] [Indexed: 11/13/2022] Open
Abstract
Light can be employed as a tool to alter and manipulate matter in many ways. An example has been the implementation of optical trapping, the so called optical tweezers, in which light can hold and move small objects with 3D control. Of interest for the Life Sciences and Biotechnology is the fact that biological objects in the size range from tens of nanometers to hundreds of microns can be precisely manipulated through this technology. In particular, it has been shown possible to optically trap and move genetic material (DNA and chromatin) using optical tweezers. Also, these biological entities can be severed, rearranged and reconstructed by the combined use of laser scissors and optical tweezers. In this review, the background, current state and future possibilities of optical tweezers and laser scissors to manipulate, rearrange and alter genetic material (DNA, chromatin and chromosomes) will be presented. Sources of undesirable effects by the optical procedure and measures to avoid them will be discussed. In addition, first tentative approaches at cellular-level genetic and organelle surgery, in which genetic material or DNA-carrying organelles are extracted out or introduced into cells, will be presented.
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Affiliation(s)
- Alfonso Blázquez-Castro
- Department of Biology, Faculty of Sciences, Autonomous University of Madrid, Madrid, Spain.,Genome Dynamics and Function Program, Genome Decoding Unit, Severo Ochoa Molecular Biology Center (CBMSO), CSIC-Autonomous University of Madrid, Madrid, Spain
| | - José Fernández-Piqueras
- Department of Biology, Faculty of Sciences, Autonomous University of Madrid, Madrid, Spain.,Genome Dynamics and Function Program, Genome Decoding Unit, Severo Ochoa Molecular Biology Center (CBMSO), CSIC-Autonomous University of Madrid, Madrid, Spain.,Institute of Health Research Jiménez Diaz Foundation, Madrid, Spain.,Consortium for Biomedical Research in Rare Diseases (CIBERER), Carlos III Institute of Health, Madrid, Spain
| | - Javier Santos
- Department of Biology, Faculty of Sciences, Autonomous University of Madrid, Madrid, Spain.,Genome Dynamics and Function Program, Genome Decoding Unit, Severo Ochoa Molecular Biology Center (CBMSO), CSIC-Autonomous University of Madrid, Madrid, Spain.,Institute of Health Research Jiménez Diaz Foundation, Madrid, Spain.,Consortium for Biomedical Research in Rare Diseases (CIBERER), Carlos III Institute of Health, Madrid, Spain
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Luo JC, Ching H, Wilson BG, Mohraz A, Botvinick EL, Venugopalan V. Laser cavitation rheology for measurement of elastic moduli and failure strain within hydrogels. Sci Rep 2020; 10:13144. [PMID: 32753667 PMCID: PMC7403306 DOI: 10.1038/s41598-020-68621-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 06/12/2020] [Indexed: 01/26/2023] Open
Abstract
We introduce laser cavitation rheology (LCR) as a minimally-invasive optical method to characterize mechanical properties within the interior of biological and synthetic aqueous soft materials at high strain-rates. We utilized time-resolved photography to measure cavitation bubble dynamics generated by the delivery of focused 500 ps duration laser radiation at λ = 532 nm within fibrin hydrogels at pulse energies of Ep = 12, 18 µJ and within polyethylene glycol (600) diacrylate (PEG (600) DA) hydrogels at Ep = 2, 5, 12 µJ. Elastic moduli and failure strains of fibrin and PEG (600) DA hydrogels were calculated from these measurements by determining parameter values which provide the best fit of the measured data to a theoretical model of cavitation bubble dynamics in a Neo-Hookean viscoelastic medium subject to material failure. We demonstrate the use of this method to retrieve the local, interior elastic modulus of these hydrogels and both the radial and circumferential failure strains.
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Affiliation(s)
- Justin C Luo
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, 92697-2715, USA
- Beckman Laser Institute & Medical Clinic, University of California, Irvine, CA, 92697-2575, USA
- Department of Biomedical Engineering, Cornell University, Ithaca, NY, USA
| | - Herman Ching
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, 916 Engineering Tower, Irvine, CA, 92697-2580, USA
| | - Bryce G Wilson
- Beckman Laser Institute & Medical Clinic, University of California, Irvine, CA, 92697-2575, USA
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, 916 Engineering Tower, Irvine, CA, 92697-2580, USA
| | - Ali Mohraz
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, 916 Engineering Tower, Irvine, CA, 92697-2580, USA
| | - Elliot L Botvinick
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, 92697-2715, USA
- Beckman Laser Institute & Medical Clinic, University of California, Irvine, CA, 92697-2575, USA
| | - Vasan Venugopalan
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, 92697-2715, USA.
- Beckman Laser Institute & Medical Clinic, University of California, Irvine, CA, 92697-2575, USA.
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, 916 Engineering Tower, Irvine, CA, 92697-2580, USA.
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Kolu E, Buyukavci R, Akturk S, Eren F, Ersoy Y. Comparison of high-intensity laser therapy and combination of transcutaneous nerve stimulation and ultrasound treatment in patients with chronic lumbar radiculopathy: A randomized single-blind study. Pak J Med Sci 2018; 34:530-534. [PMID: 30034410 PMCID: PMC6041553 DOI: 10.12669/pjms.343.14345] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Objective: To compare the effects of high-intensity laser therapy (HILT) and a combination of transcutaneous nerve stimulation (TENS) with ultrasound (US) therapy on pain and functionality in patients with chronic lumbar radiculopathy. Methods: This prospective randomized comparative study was conducted in Department of physical medicine and rehabilitation, Turgut Ozal Medicine Center, Malatya, Turkey from April 2016 to September 2016. A total of 54 patients with chronic lumbar radiculopathy were enrolled in this study. The patients were randomly divided into two groups: Group 1 (n:27) received 10 sessions of a combination of hot pack, TENS, US and exercise, and Group 2 (n:27) received hot pack, HILT and exercise. The outcomes measured were low back with unilateral leg pain level measured by visual analog scale (VAS) and functionality measured with the Oswestry Disability Index (ODI) at the end of the therapy and four weeks later. p-value less than 0.05 considered statistically significant. Results: In two groups, VAS (low back with unilateral leg pain) and ODI scores showed significant changes. At the end of the 2 weeks intervention, participants in Group-1 showed a significantly greater decrease in pain than participants in Group-2. Statistically significant differences in pain variation and functionality (VAS and ODI) were observed four weeks after treatment sessions for participants in the TENS+US therapy group compared with participants in the HILT group. Conclusion: HILT and TENS+US combined with exercise were effective treatment modalities in decreasing the VAS and ODI scores. TENS+US combined with exercises were more effective than HILT combined with exercise.
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Affiliation(s)
- Emine Kolu
- Emine Kolu, Inonu University, Faculty of Medicine, Department of Physical Medicine and Rehabilitation, Malatya, Turkey
| | - Raikan Buyukavci
- Raikan Buyukavci, Inonu University, Faculty of Medicine, Department of Physical Medicine and Rehabilitation, Malatya, Turkey
| | - Semra Akturk
- Semra Akturk, Inonu University, Faculty of Medicine, Department of Physical Medicine and Rehabilitation, Malatya, Turkey
| | - Fatma Eren
- Fatma Eren, Inonu University, Faculty of Medicine, Department of Physical Medicine and Rehabilitation, Malatya, Turkey
| | - Yuksel Ersoy
- Yuksel Ersoy, Inonu University, Faculty of Medicine, Department of Physical Medicine and Rehabilitation, Malatya, Turkey
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Raos BJ, Graham ES, Unsworth CP. Nanosecond UV lasers stimulate transient Ca2+elevations in human hNT astrocytes. J Neural Eng 2017; 14:035001. [DOI: 10.1088/1741-2552/aa5f27] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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7
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Hinaux H, Recher G, Alié A, Legendre L, Blin M, Rétaux S. Lens apoptosis in the Astyanax blind cavefish is not triggered by its small size or defects in morphogenesis. PLoS One 2017; 12:e0172302. [PMID: 28235048 PMCID: PMC5325263 DOI: 10.1371/journal.pone.0172302] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 02/02/2017] [Indexed: 01/08/2023] Open
Abstract
Blindness is a convergent trait in many cave animals of various phyla. Astyanax mexicanus cavefish is one of the best studied cave animals; however the mechanisms underlying eye degeneration in this species are not yet completely understood. The lens seems to play a central role, but only relatively late differentiation defects have been implicated in the cavefish lens apoptosis phenotype so far. Here, we used genetic crosses between Astyanax cavefish and surface fish to confirm that during development, lens size is independent of retina size. We then investigated whether the small size of the cavefish lens could directly cause cell death. Laser ablation experiments of lens placode cells in surface fish embryos showed that a small lens size is not sufficient to trigger lens apoptosis. We further examined potential lens morphogenesis defects through classical histology and live-imaging microscopy. From lens placode to lens ball, we found that lens invagination and formation of the lens epithelium and fiber cells occur normally in cavefish. We conclude that the main and deleterious defect in the Astyanax cavefish lens must concern the molecular control of lens cell function.
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Affiliation(s)
- Hélène Hinaux
- DECA group, Paris-Saclay Institute of Neuroscience, UMR9197, CNRS, Université Paris Sud, Université Paris-Saclay, Avenue de la terrasse, Gif-sur-Yvette, France
| | - Gaëlle Recher
- Plateforme BioEmergence, USR3695, CNRS, Université Paris-Saclay, Avenue de la terrasse, Gif-sur-Yvette, France
| | - Alexandre Alié
- DECA group, Paris-Saclay Institute of Neuroscience, UMR9197, CNRS, Université Paris Sud, Université Paris-Saclay, Avenue de la terrasse, Gif-sur-Yvette, France
| | - Laurent Legendre
- UMS AMAGEN (UMS 3504 CNRS / UMS 1374 INRA), CNRS, INRA, Université Paris-Saclay, Avenue de la terrasse, Gif-sur-Yvette, France
| | - Maryline Blin
- DECA group, Paris-Saclay Institute of Neuroscience, UMR9197, CNRS, Université Paris Sud, Université Paris-Saclay, Avenue de la terrasse, Gif-sur-Yvette, France
| | - Sylvie Rétaux
- DECA group, Paris-Saclay Institute of Neuroscience, UMR9197, CNRS, Université Paris Sud, Université Paris-Saclay, Avenue de la terrasse, Gif-sur-Yvette, France
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Hydrodynamic determinants of cell necrosis and molecular delivery produced by pulsed laser microbeam irradiation of adherent cells. Biophys J 2014; 105:2221-31. [PMID: 24209868 DOI: 10.1016/j.bpj.2013.09.027] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Revised: 08/28/2013] [Accepted: 09/12/2013] [Indexed: 12/11/2022] Open
Abstract
Time-resolved imaging, fluorescence microscopy, and hydrodynamic modeling were used to examine cell lysis and molecular delivery produced by picosecond and nanosecond pulsed laser microbeam irradiation in adherent cell cultures. Pulsed laser microbeam radiation at λ = 532 nm was delivered to confluent monolayers of PtK2 cells via a 40×, 0.8 NA microscope objective. Using laser microbeam pulse durations of 180-1100 ps and pulse energies of 0.5-10.5 μJ, we examined the resulting plasma formation and cavitation bubble dynamics that lead to laser-induced cell lysis, necrosis, and molecular delivery. The cavitation bubble dynamics are imaged at times of 0.5 ns to 50 μs after the pulsed laser microbeam irradiation, and fluorescence assays assess the resulting cell viability and molecular delivery of 3 kDa dextran molecules. Reductions in both the threshold laser microbeam pulse energy for plasma formation and the cavitation bubble energy are observed with decreasing pulse duration. These energy reductions provide for increased precision of laser-based cellular manipulation including cell lysis, cell necrosis, and molecular delivery. Hydrodynamic analysis reveals critical values for the shear-stress impulse generated by the cavitation bubble dynamics governs the location and spatial extent of cell necrosis and molecular delivery independent of pulse duration and pulse energy. Specifically, cellular exposure to a shear-stress impulse J≳0.1 Pa s ensures cell lysis or necrosis, whereas exposures in the range of 0.035≲J≲0.1 Pa s preserve cell viability while also enabling molecular delivery of 3 kDa dextran. Exposure to shear-stress impulses of J≲0.035 Pa s leaves the cells unaffected. Hydrodynamic analysis of these data, combined with data from studies of 6 ns microbeam irradiation, demonstrates the primacy of shear-stress impulse in determining cellular outcome resulting from pulsed laser microbeam irradiation spanning a nearly two-orders-of-magnitude range of pulse energy and pulse duration. These results provide a mechanistic foundation and design strategy applicable to a broad range of laser-based cellular manipulation procedures.
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Heinemann D, Schomaker M, Kalies S, Schieck M, Carlson R, Murua Escobar H, Ripken T, Meyer H, Heisterkamp A. Gold nanoparticle mediated laser transfection for efficient siRNA mediated gene knock down. PLoS One 2013; 8:e58604. [PMID: 23536802 PMCID: PMC3594183 DOI: 10.1371/journal.pone.0058604] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 02/05/2013] [Indexed: 11/19/2022] Open
Abstract
Laser based transfection methods have proven to be an efficient and gentle alternative to established molecule delivery methods like lipofection or electroporation. Among the laser based methods, gold nanoparticle mediated laser transfection bears the major advantage of high throughput and easy usability. This approach uses plasmon resonances on gold nanoparticles unspecifically attached to the cell membrane to evoke transient and spatially defined cell membrane permeabilization. In this study, we explore the parameter regime for gold nanoparticle mediated laser transfection for the delivery of molecules into cell lines and prove its suitability for siRNA mediated gene knock down. The developed setup allows easy usage and safe laser operation in a normal lab environment. We applied a 532 nm Nd:YAG microchip laser emitting 850 ps pulses at a repetition rate of 20.25 kHz. Scanning velocities of the laser spot over the sample of up to 200 mm/s were tested without a decline in perforation efficiency. This velocity leads to a process speed of ∼8 s per well of a 96 well plate. The optimal particle density was determined to be ∼6 particles per cell using environmental scanning electron microscopy. Applying the optimized parameters transfection efficiencies of 88% were achieved in canine pleomorphic adenoma ZMTH3 cells using a fluorescent labeled siRNA while maintaining a high cell viability of >90%. Gene knock down of d2-EGFP was demonstrated and validated by fluorescence repression and western blot analysis. On basis of our findings and established mathematical models we suppose a mixed transfection mechanism consisting of thermal and multiphoton near field effects. Our findings emphasize that gold nanoparticle mediated laser transfection provides an excellent tool for molecular delivery for both, high throughput purposes and the transfection of sensitive cells types.
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Affiliation(s)
- Dag Heinemann
- Biomedical Optics Department, Laser Zentrum Hannover e.V., Hannover, Germany.
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Chang WC, Hawkes E, Keller CG, Sretavan DW. Axon repair: surgical application at a subcellular scale. WILEY INTERDISCIPLINARY REVIEWS-NANOMEDICINE AND NANOBIOTECHNOLOGY 2010; 2:151-61. [PMID: 20101712 DOI: 10.1002/wnan.76] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Injury to the nervous system is a common occurrence after trauma. Severe cases of injury exact a tremendous personal cost and place a significant healthcare burden on society. Unlike some tissues in the body that exhibit self healing, nerve cells that are injured, particularly those in the brain and spinal cord, are incapable of regenerating circuits by themselves to restore neurological function. In recent years, researchers have begun to explore whether micro/nanoscale tools and materials can be used to address this major challenge in neuromedicine. Efforts in this area have proceeded along two lines. One is the development of new nanoscale tissue scaffold materials to act as conduits and stimulate axon regeneration. The other is the use of novel cellular-scale surgical micro/nanodevices designed to perform surgical microsplicing and the functional repair of severed axons. We discuss results generated by these two approaches and hurdles confronting both strategies.
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Affiliation(s)
- Wesley C Chang
- Neuroscience and Bioengineering Programs, Department of Ophthalmology, University of California, San Francisco, CA 94143, USA
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O'Brien GS, Rieger S, Martin SM, Cavanaugh AM, Portera-Cailliau C, Sagasti A. Two-photon axotomy and time-lapse confocal imaging in live zebrafish embryos. J Vis Exp 2009:1129. [PMID: 19229185 PMCID: PMC2726581 DOI: 10.3791/1129] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Zebrafish have long been utilized to study the cellular and molecular mechanisms of development by time-lapse imaging of the living transparent embryo. Here we describe a method to mount zebrafish embryos for long-term imaging and demonstrate how to automate the capture of time-lapse images using a confocal microscope. We also describe a method to create controlled, precise damage to individual branches of peripheral sensory axons in zebrafish using the focused power of a femtosecond laser mounted on a two-photon microscope. The parameters for successful two-photon axotomy must be optimized for each microscope. We will demonstrate two-photon axotomy on both a custom built two-photon microscope and a Zeiss 510 confocal/two-photon to provide two examples. Zebrafish trigeminal sensory neurons can be visualized in a transgenic line expressing GFP driven by a sensory neuron specific promoter (1). We have adapted this zebrafish trigeminal model to directly observe sensory axon regeneration in living zebrafish embryos. Embryos are anesthetized with tricaine and positioned within a drop of agarose as it solidifies. Immobilized embryos are sealed within an imaging chamber filled with phenylthiourea (PTU) Ringers. We have found that embryos can be continuously imaged in these chambers for 12-48 hours. A single confocal image is then captured to determine the desired site of axotomy. The region of interest is located on the two-photon microscope by imaging the sensory axons under low, non-damaging power. After zooming in on the desired site of axotomy, the power is increased and a single scan of that defined region is sufficient to sever the axon. Multiple location time-lapse imaging is then set up on a confocal microscope to directly observe axonal recovery from injury.
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Affiliation(s)
- Georgeann S O'Brien
- Department of Molecular Cell and Developmental Biology, University of California, Los Angeles, USA.
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Quinto-Su PA, To'a Salazar G, Sims CE, Allbritton NL, Venugopalan V. Mechanisms of pulsed laser microbeam release of SU-8 polymer "micropallets" for the collection and separation of adherent cells. Anal Chem 2008; 80:4675-9. [PMID: 18489124 DOI: 10.1021/ac800129a] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The release of individual polymer micropallets from glass substrates using highly focused laser pulses has been demonstrated for the efficient separation, collection, and expansion of single, adherent cells from a heterogeneous cell population. Here, we use fast-frame photography to examine the mechanism and dynamics of micropallet release produced by pulsed laser microbeam irradiation at lambda = 532 nm using pulse durations ranging between 240 ps and 6 ns. The time-resolved images show the laser microbeam irradiation to result in plasma formation at the interface between the glass coverslip and the polymer micropallet. The plasma formation results in the emission of a shock wave and the ablation of material within the focal volume. Ablation products are generated at high pressure due to the confinement offered by the polymer adhesion to the glass substrate. The ablation products expand underneath the micropallet on a time scale of several hundred nanoseconds. This expansion disrupts the polymer-glass interface and accomplishes the release of the pallet from its glass substrate on the microsecond time scale (approximately 1.5 micros). Our experimental investigation demonstrates that the threshold energy for pallet release is constant (approximately 2 microJ) over a 25-fold range of pulse duration spanning the picosecond to nanosecond domain. Taken together, these results implicate that pallet release accomplished via pulsed laser microbeam irradiation is an energy-driven plasma-mediated ablation process.
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Affiliation(s)
- Pedro A Quinto-Su
- Department of Chemical Engineering & Materials Science, University of California, Irvine, Irvine, California 92697-2575, USA
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