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Abstract
Introduction: Alcohol (ethanol) and cannabis are among the most widely used recreational drugs in the world. With increased efforts toward legalization of cannabis, there is an alarming trend toward the concomitant (including simultaneous) use of cannabis products with alcohol for recreational purpose. While each drug possesses a distinct effect on cerebral circulation, the consequences of their simultaneous use on cerebral artery diameter have never been studied. Thus, we set to address the effect of simultaneous application of alcohol and (-)-trans-Δ-9-tetrahydrocannabinol (THC) on cerebral artery diameter. Materials and Methods: We used Sprague-Dawley rats because rat cerebral circulation closely mimics morphology, ultrastructure, and function of cerebral circulation of humans. We focused on the middle cerebral artery (MCA) because it supplies blood to the largest brain territory when compared to any other cerebral artery stemming from the circle of Willis. Experiments were performed on pressurized MCA ex vivo, and in cranial windows in vivo. Ethanol and THC were probed at physiologically relevant concentrations. Researchers were "blind" to experimental group identity during data analysis to avoid bias. Results: In males, ethanol mixed with THC resulted in greater constriction of ex vivo pressurized MCA when compared to the effects exerted by separate application of each drug. In females, THC, ethanol, or their mixture failed to elicit measurable effect. Vasoconstriction by ethanol/THC mixture was ablated by either endothelium removal or pharmacological block of calcium- and voltage-gated potassium channels of large conductance (BK type) and cannabinoid receptors. Block of prostaglandin production and of endothelin receptors also blunted constriction by ethanol/THC. In males, the in vivo constriction of MCA by ethanol/THC did not differ from ethanol alone. In females, the in vivo constriction of this artery by ethanol was significantly smaller than in males. However, artery constriction by ethanol/THC did not differ from the constriction in males. Conclusions: Our data point at the complex nature of the cerebrovascular effects elicited by simultaneous use of ethanol and THC. These effects include both local and systemic components.
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Affiliation(s)
- Alexandria Slayden
- Department of Pharmacology, Addiction Science and Toxicology, College of Medicine, The University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Steven Mysiewicz
- Department of Pharmacology, Addiction Science and Toxicology, College of Medicine, The University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Kelsey North
- Department of Pharmacology, Addiction Science and Toxicology, College of Medicine, The University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Alex Dopico
- Department of Pharmacology, Addiction Science and Toxicology, College of Medicine, The University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Anna Bukiya
- Department of Pharmacology, Addiction Science and Toxicology, College of Medicine, The University of Tennessee Health Science Center, Memphis, Tennessee, USA
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2
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Luo Z, Xu H, Samanta S, Zhang R, Luo G, Wang Y, Liu L, Weng X, He J, Liao C, Wang Y, Guo B, Qu J. Long-Term Repeatable In Vivo Monitoring of Amyloid-β Plaques and Vessels in Alzheimer's Disease Mouse Model with Combined TPEF/CARS Microscopy. Biomedicines 2022; 10. [PMID: 36428517 DOI: 10.3390/biomedicines10112949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 10/27/2022] [Accepted: 11/08/2022] [Indexed: 11/18/2022] Open
Abstract
Long-term, repeatable monitoring of the appearance and progress of Alzheimer's disease (AD) in real time can be extremely beneficial to acquire highly reliable diagnostic insights, which is crucial for devising apt strategies towards effective AD treatment. Herein, we present an optimized innovative cranial window imaging method for the long-term repeatable imaging of amyloid-β (Aβ) plaques and vessels in an AD mouse model. Basically, two-photon excitation fluorescence (TPEF) microscopy was used to monitor the fluorescently labeled Aβ plaques, whereas the label-free blood vessels were studied using coherent anti-Stokes Raman scattering (CARS) microscopy in the live in vivo AD mouse model. It was possible to clearly observe the Aβ deposition and vascular structure in the target cortex localization for 31 weeks in the AD mouse model using this method. The combined TPEF/CARS imaging studies were also instrumental in realizing the relationship between the tendency of Aβ deposition and ageing. Essentially, the progression of cerebral amyloid angiopathy (CAA) in the AD mouse model was quantitatively characterized, which revealed that the proportion Aβ deposition in the unit vessel can increase from 13.63% to 28.80% upon increasing the age of mice from 8 months old to 14 months old. The proposed imaging method provided an efficient, safe, repeatable platform with simple target localization aptitude towards monitoring the brain tissues, which is an integral part of studying any brain-related physiological or disease conditions to extract crucial structural and functional information.
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3
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Yin R, Noble BC, He F, Zolotavin P, Rathore H, Jin Y, Sevilla N, Xie C, Luan L. Chronic co-implantation of ultraflexible neural electrodes and a cranial window. Neurophotonics 2022; 9:032204. [PMID: 35036472 PMCID: PMC8756486 DOI: 10.1117/1.nph.9.3.032204] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Accepted: 11/04/2021] [Indexed: 06/01/2023]
Abstract
Significance: Electrophysiological recording and optical imaging are two prevalent neurotechnologies with complementary strengths, the combined application of which can significantly improve our capacity in deciphering neural circuits. Flexible electrode arrays can support longitudinal optical imaging in the same brain region, but their mechanical flexibility makes surgical preparation challenging. Here, we provide a step-by-step protocol by which an ultraflexible nanoelectronic thread is co-implanted with a cranial window in a single surgery to enable chronic, dual-modal measurements. Aim: The method uses 1 - μ m -thick polymer neural electrodes which conform to the site of implantation. The mechanical flexibility of the probe allows bending without breaking and enables long-lasting electrophysiological recordings of single-unit activities and concurrent, high-resolution optical imaging through the cranial window. Approach: The protocol describes methods and procedures to co-implant an ultraflexible electrode array and a glass cranial window in the mouse neocortex. The implantation strategy includes temporary attachment of flexible electrodes to a retractable tungsten-microwire insertion shuttle, craniotomy, stereotaxic insertion of the electrode array, skull fixation of the cranial window and electrode, and installation of a head plate. Results: The resultant implant allows simultaneous interrogation of brain activity both electrophysiologically and optically for several months. Importantly, a variety of optical imaging modalities, including wide-field fluorescent imaging, two-photon microscopy, and functional optical imaging, can be readily applied to the specific brain region where ultraflexible electrodes record from. Conclusions: The protocol describes a method for co-implantation of ultraflexible neural electrodes and a cranial window for chronic, multimodal measurements of brain activity in mice. Device preparation and surgical implantation are described in detail to guide the adaptation of these methods for other flexible neural implants and cranial windows.
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Affiliation(s)
- Rongkang Yin
- Rice University, Department of Electrical and Computer Engineering, Houston, Texas, United States
- Rice University, Rice Neuroengineering Initiative, Houston, Texas, United States
| | - Brian C. Noble
- Rice University, Rice Neuroengineering Initiative, Houston, Texas, United States
- Rice University, Applied Physics Graduate Program, Houston, Texas, United States
| | - Fei He
- Rice University, Department of Electrical and Computer Engineering, Houston, Texas, United States
- Rice University, Rice Neuroengineering Initiative, Houston, Texas, United States
| | - Pavlo Zolotavin
- Rice University, Department of Electrical and Computer Engineering, Houston, Texas, United States
- Rice University, Rice Neuroengineering Initiative, Houston, Texas, United States
| | - Haad Rathore
- Rice University, Rice Neuroengineering Initiative, Houston, Texas, United States
- Rice University, Applied Physics Graduate Program, Houston, Texas, United States
| | - Yifu Jin
- Rice University, Department of Electrical and Computer Engineering, Houston, Texas, United States
- Rice University, Rice Neuroengineering Initiative, Houston, Texas, United States
| | - Nicole Sevilla
- Rice University, Rice Neuroengineering Initiative, Houston, Texas, United States
- Rice University, Department of Bioengineering, Houston, Texas, United States
| | - Chong Xie
- Rice University, Department of Electrical and Computer Engineering, Houston, Texas, United States
- Rice University, Rice Neuroengineering Initiative, Houston, Texas, United States
- Rice University, Department of Bioengineering, Houston, Texas, United States
| | - Lan Luan
- Rice University, Department of Electrical and Computer Engineering, Houston, Texas, United States
- Rice University, Rice Neuroengineering Initiative, Houston, Texas, United States
- Rice University, Department of Bioengineering, Houston, Texas, United States
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4
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Coelho-Santos V, Tieu T, Shih AY. Reinforced thinned-skull window for repeated imaging of the neonatal mouse brain. Neurophotonics 2022; 9:031918. [PMID: 35673538 PMCID: PMC9163199 DOI: 10.1117/1.nph.9.3.031918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 05/03/2022] [Indexed: 06/15/2023]
Abstract
Significance: Two-photon microscopy is a powerful tool for in vivo imaging of the mammalian brain at cellular to subcellular resolution. However, resources that describe methods for imaging live newborn mice have remained sparse. Aim: We describe a non-invasive cranial window procedure for longitudinal imaging of neonatal mice. Approach: We demonstrate construction of the cranial window by iterative shaving of the calvarium of P0 to P12 mouse pups. We use the edge of a syringe needle and scalpel blades to thin the bone to ∼ 15 - μ m thickness. The window is then reinforced with cyanoacrylate glue and a coverslip to promote stability and optical access for at least a week. The head cap also includes a light-weight aluminum flange for head-fixation during imaging. Results: The resulting chronic thinned-skull window enables in vivo imaging to a typical cortical depth of ∼ 200 μ m without disruption of the intracranial environment. We highlight techniques to measure vascular structure and blood flow during development, including use of intravenous tracers and transgenic mice to label the blood plasma and vascular cell types, respectively. Conclusions: This protocol enables direct visualization of the developing neurogliovascular unit in the live neonatal brain during both normal and pathological states.
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Affiliation(s)
- Vanessa Coelho-Santos
- Seattle Children’s Research Institute, Center for Developmental Biology and Regenerative Medicine, Seattle, Washington, United States
- University of Washington, Department of Pediatrics, Seattle, Washington, United States
| | - Taryn Tieu
- Seattle Children’s Research Institute, Center for Developmental Biology and Regenerative Medicine, Seattle, Washington, United States
| | - Andy Y. Shih
- Seattle Children’s Research Institute, Center for Developmental Biology and Regenerative Medicine, Seattle, Washington, United States
- University of Washington, Department of Pediatrics, Seattle, Washington, United States
- University of Washington, Department of Bioengineering, Seattle, Washington, United States
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5
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Xu C, Uahengo G, Rudnicki C, Hung C, Huang A, Xu Q, Chen Y, Halaney DL, Garay JE, Mangolini L, Aguilar G, Liu HH. Nanocrystalline Yttria-Stabilized Zirconia Ceramics for Cranial Window Applications. ACS Appl Bio Mater 2022; 5:2664-2675. [PMID: 35671525 DOI: 10.1021/acsabm.2c00119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Transparent yttria-stabilized zirconia (YSZ) ceramics are promising for cranial window applications because of their good mechanical and optical properties as well as biocompatibility. YSZ discs with different yttria concentrations were either processed via current-activated pressure-assisted densification (CAPAD) using commercial nanoparticles or densified via spark plasma sintering (SPS) using pyrolysis-synthesized nanoparticles in-house. This study provided critical results to screen composition, processing, microstructure, and cytocompatibility of transparent YSZ discs for cranial window applications. CAPAD-processed YSZ discs with 6 or 8 mol % yttria (6YSZ and 8YSZ) and SPS-densified YSZ discs with 4 mol % yttria (4YSZ_P) showed 200-350 nm polycrystalline grains containing 20-30 nm crystallite domains. SPS-densified YSZ discs with 8 mol % yttria (8YSZ_P) showed larger polycrystalline grains of 819 ± 155 nm with 29 ± 5 nm crystallite domains. CAPAD-processed YSZ discs with 3 mol % yttria (3YSZ) showed 39 ± 9 nm grains. Bone-marrow-derived stem cells (BMSCs) on the polished YSZ discs showed statistically higher spreading areas than those on the unpolished YSZ discs of the same compositions. Generally, polished 8YSZ, 4YSZ_P, and 8YSZ_P discs and unpolished 8YSZ_R, 4YSZ_PR, and 8YSZ_PR discs had lower average cell adhesion densities than other YSZ discs under direct contact conditions. Under indirect contact conditions, all the YSZ disc groups showed similar average cell adhesion densities to the Cell-only control. The groups of polished 4YSZ_P and 8YSZ_P discs, unpolished 4YSZ_PR and 8YSZ_PR discs, and particle control of 8YSZ_Pnp showed higher Y3+ ion concentrations than other groups. No mineral deposition was detected on the polished YSZ discs after cell culture. Considering multiple factors such as cytocompatibility, cell adhesion density, Y3+ ion release, mineral deposition, and optical transparency collectively, 8YSZ may be the best candidate for the cranial window applications. Further studies are needed to evaluate the long-term transparency and biocompatibility of YSZ discs.
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Affiliation(s)
- Changlu Xu
- Materials Science and Engineering Program, University of California, Riverside, Riverside, California 92521, United States
| | - Gottlieb Uahengo
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, California 92093, United States
| | - Christopher Rudnicki
- Department of Mechanical Engineering, University of California, Riverside, Riverside, California 92521, United States
| | - Chengi Hung
- Department of Bioengineering, University of California, Riverside, Riverside, California 92521, United States
| | - Aaron Huang
- Department of Bioengineering, University of California, Riverside, Riverside, California 92521, United States
| | - Queenie Xu
- Department of Bioengineering, University of California, Riverside, Riverside, California 92521, United States
| | - Yiqing Chen
- Materials Science and Engineering Program, University of California, Riverside, Riverside, California 92521, United States
| | - David L Halaney
- Department of Mechanical Engineering, University of California, Riverside, Riverside, California 92521, United States
| | - Javier E Garay
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, California 92093, United States
| | - Lorenzo Mangolini
- Materials Science and Engineering Program, University of California, Riverside, Riverside, California 92521, United States.,Department of Mechanical Engineering, University of California, Riverside, Riverside, California 92521, United States
| | - Guillermo Aguilar
- Department of Mechanical Engineering, University of California, Riverside, Riverside, California 92521, United States
| | - Huinan Hannah Liu
- Materials Science and Engineering Program, University of California, Riverside, Riverside, California 92521, United States.,Department of Bioengineering, University of California, Riverside, Riverside, California 92521, United States.,Stem Cell Center, University of California, Riverside, Riverside, California 92521, United States
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6
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Sciortino VM, Tran A, Sun N, Cao R, Sun T, Sun YY, Yan P, Zhong F, Zhou Y, Kuan CY, Lee JM, Hu S. Longitudinal cortex-wide monitoring of cerebral hemodynamics and oxygen metabolism in awake mice using multi-parametric photoacoustic microscopy. J Cereb Blood Flow Metab 2021; 41:3187-3199. [PMID: 34304622 PMCID: PMC8669277 DOI: 10.1177/0271678x211034096] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Multi-parametric photoacoustic microscopy (PAM) has emerged as a promising new technique for high-resolution quantification of hemodynamics and oxygen metabolism in the mouse brain. In this work, we have extended the scope of multi-parametric PAM to longitudinal, cortex-wide, awake-brain imaging with the use of a long-lifetime (24 weeks), wide-field (5 × 7 mm2), light-weight (2 g), dual-transparency (i.e., light and ultrasound) cranial window. Cerebrovascular responses to the window installation were examined in vivo, showing a complete recovery in 18 days. In the 22-week monitoring after the recovery, no dura thickening, skull regrowth, or changes in cerebrovascular structure and function were observed. The promise of this technique was demonstrated by monitoring vascular and metabolic responses of the awake mouse brain to ischemic stroke throughout the acute, subacute, and chronic stages. Side-by-side comparison of the responses in the ipsilateral (injury) and contralateral (control) cortices shows that despite an early recovery of cerebral blood flow and an increase in microvessel density, a long-lasting deficit in cerebral oxygen metabolism was observed throughout the chronic stage in the injured cortex, part of which proceeded to infarction. This longitudinal, functional-metabolic imaging technique opens new opportunities to study the chronic progression and therapeutic responses of neurovascular diseases.
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Affiliation(s)
- Vincent M Sciortino
- Department of Biomedical Engineering, 2358University of Virginia, University of Virginia, Charlottesville, VA, USA
| | - Angela Tran
- Department of Biology, 2358University of Virginia, University of Virginia, Charlottesville, VA, USA
| | - Naidi Sun
- Department of Biomedical Engineering, 2358University of Virginia, University of Virginia, Charlottesville, VA, USA.,Department of Neurology, Washington University in St. Louis, St. Louis, MO, USA
| | - Rui Cao
- Department of Biomedical Engineering, 2358University of Virginia, University of Virginia, Charlottesville, VA, USA
| | - Tao Sun
- Department of Biomedical Engineering, 2358University of Virginia, University of Virginia, Charlottesville, VA, USA.,Department of Neurology, Washington University in St. Louis, St. Louis, MO, USA
| | - Yu-Yo Sun
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Ping Yan
- Department of Neuroscience, 2358University of Virginia, University of Virginia, Charlottesville, VA, USA
| | - Fenghe Zhong
- Department of Biomedical Engineering, 2358University of Virginia, University of Virginia, Charlottesville, VA, USA.,Department of Neurology, Washington University in St. Louis, St. Louis, MO, USA
| | - Yifeng Zhou
- Department of Biomedical Engineering, 2358University of Virginia, University of Virginia, Charlottesville, VA, USA.,Department of Neurology, Washington University in St. Louis, St. Louis, MO, USA
| | - Chia-Yi Kuan
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Jin-Moo Lee
- Department of Neuroscience, 2358University of Virginia, University of Virginia, Charlottesville, VA, USA.,Department of Neurology, Washington University in St. Louis, St. Louis, MO, USA
| | - Song Hu
- Department of Biomedical Engineering, 2358University of Virginia, University of Virginia, Charlottesville, VA, USA.,Department of Neurology, Washington University in St. Louis, St. Louis, MO, USA
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7
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Mitsuda S, Uzawa K, Sawa M, Ando T, Yoshikawa T, Miyao H, Yorozu T, Ushiyama A. Vascular Endothelial Glycocalyx Plays a Role in the Obesity Paradox According to Intravital Observation. Front Cardiovasc Med 2021; 8:727888. [PMID: 34796208 PMCID: PMC8593246 DOI: 10.3389/fcvm.2021.727888] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Accepted: 10/12/2021] [Indexed: 11/13/2022] Open
Abstract
According to the “obesity paradox,” for severe conditions, individuals with obesity may be associated with a higher survival rate than those who are lean. However, the physiological basis underlying the mechanism of the obesity paradox remains unknown. We hypothesize that the glycocalyx in obese mice is thicker and more resistant to inflammatory stress than that in non-obese mice. In this study, we employed intravital microscopy to elucidate the differences in the vascular endothelial glycocalyx among three groups of mice fed diets with different fat concentrations. Male C57BL/6N mice were divided into three diet groups: low-fat (fat: 10% kcal), medium-fat (fat: 45% kcal), and high-fat (fat: 60% kcal) diet groups. Mice were fed the respective diet from 3 weeks of age, and a chronic cranial window was installed at 8 weeks of age. At 9 weeks of age, fluorescein isothiocyanate-labeled wheat germ agglutinin was injected to identify the glycocalyx layer, and brain pial microcirculation was observed within the cranial windows. We randomly selected arterioles of diameter 15–45 μm and captured images. The mean index of the endothelial glycocalyx was calculated using image analysis and defined as the glycocalyx index. The glycocalyx indexes of the high-fat and medium-fat diet groups were significantly higher than those of the low-fat diet group (p < 0.05). There was a stronger positive correlation between vessel diameter and glycocalyx indexes in the high-fat and medium-fat diet groups than in the low-fat diet group. The glycocalyx indexes of the non-sepsis model in the obese groups were higher than those in the control group for all vessel diameters, and the positive correlation was also stronger. These findings indicate that the index of the original glycocalyx may play an important role in the obesity paradox.
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Affiliation(s)
- Shingo Mitsuda
- Department of Anesthesiology, National Disaster Medical Center, Tokyo, Japan
| | - Kohji Uzawa
- Department of Anesthesiology, Kyorin University School of Medicine, Tokyo, Japan
| | - Marie Sawa
- Meiji Pharmaceutical University Graduate School of Pharmaceutical Sciences, Tokyo, Japan
| | - Tadao Ando
- Department of Anesthesiology, Kyorin University School of Medicine, Tokyo, Japan
| | - Takahiro Yoshikawa
- Department of Anesthesiology, Kyorin University School of Medicine, Tokyo, Japan
| | - Hideki Miyao
- Department of Anesthesiology, Saitama Medical Center, Saitama Medical University, Saitama-Ken, Japan
| | - Tomoko Yorozu
- Department of Anesthesiology, Kyorin University School of Medicine, Tokyo, Japan
| | - Akira Ushiyama
- Department of Environmental Health, National Institute of Public Health, Saitama, Japan
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8
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Fedinec AL, Liu J, Zhang R, Harsono M, Pourcyrous M, Parfenova H. The cold receptor TRPM8 activation leads to attenuation of endothelium-dependent cerebral vascular functions during head cooling. J Cereb Blood Flow Metab 2021; 41:2897-2906. [PMID: 34013806 PMCID: PMC8756482 DOI: 10.1177/0271678x211018035] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Using the cranial window technique, we investigated acute effects of head cooling on cerebral vascular functions in newborn pigs. Head cooling lowered the rectal and extradural brain temperatures to 34.3 ± 0.6°C and 26.1 ± 0.6°C, respectively. During the 3-h hypothermia period, responses of pial arterioles to endothelium-dependent dilators bradykinin and glutamate were reduced, whereas the responses to hypercapnia and an endothelium-independent dilator sodium nitroprusside (SNP) remained intact. All vasodilator responses were restored after rewarming, suggesting that head cooling did not produce endothelial injury. We tested the hypothesis that the cold-sensitive TRPM8 channel is involved in attenuation of cerebrovascular functions. TRPM8 is immunodetected in cerebral vessels and in the brain parenchyma. During normothermia, the TRPM8 agonist icilin produced constriction of pial arterioles that was antagonized by the channel blocker AMTB. Icilin reduced dilation of pial arterioles to bradykinin and glutamate but not to hypercapnia and SNP, thus mimicking the effects of head cooling on vascular functions. AMTB counteracted the impairment of endothelium-dependent vasodilation caused by hypothermia or icilin. Overall, mild hypothermia produced by head cooling leads to acute reversible reduction of selected endothelium-dependent cerebral vasodilator functions via TRPM8 activation, whereas cerebral arteriolar smooth muscle functions are largely preserved.
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Affiliation(s)
| | | | | | | | | | - Helena Parfenova
- Helena Parfenova, Department of Physiology, University of Tennessee Health Science Center, 956 Court Avenue, Suite E332, Memphis, TN 38163, USA.
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9
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Wang HL, Chen JW, Yang SH, Lo YC, Pan HC, Liang YW, Wang CF, Yang Y, Kuo YT, Lin YC, Chou CY, Lin SH, Chen YY. Multimodal Optical Imaging to Investigate Spatiotemporal Changes in Cerebrovascular Function in AUDA Treatment of Acute Ischemic Stroke. Front Cell Neurosci 2021; 15:655305. [PMID: 34149359 PMCID: PMC8209306 DOI: 10.3389/fncel.2021.655305] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 05/10/2021] [Indexed: 01/03/2023] Open
Abstract
Administration of 12-(3-adamantan-1-yl-ureido)-dodecanoic acid (AUDA) has been demonstrated to alleviate infarction following ischemic stroke. Reportedly, the main effect of AUDA is exerting anti-inflammation and neovascularization via the inhibition of soluble epoxide hydrolase. However, the major contribution of this anti-inflammation and neovascularization effect in the acute phase of stroke is not completely elucidated. To investigate the neuroprotective effects of AUDA in acute ischemic stroke, we combined laser speckle contrast imaging and optical intrinsic signal imaging techniques with the implantation of a lab-designed cranial window. Forepaw stimulation was applied to assess the functional changes via measuring cerebral metabolic rate of oxygen (CMRO2) that accompany neural activity. The rats that received AUDA in the acute phase of photothrombotic ischemia stroke showed a 30.5 ± 8.1% reduction in the ischemic core, 42.3 ± 15.1% reduction in the ischemic penumbra (p < 0.05), and 42.1 ± 4.6% increase of CMRO2 in response to forepaw stimulation at post-stroke day 1 (p < 0.05) compared with the control group (N = 10 for each group). Moreover, at post-stroke day 3, increased functional vascular density was observed in AUDA-treated rats (35.9 ± 1.9% higher than that in the control group, p < 0.05). At post-stroke day 7, a 105.4% ± 16.4% increase of astrocytes (p < 0.01), 30.0 ± 10.9% increase of neurons (p < 0.01), and 65.5 ± 15.0% decrease of microglia (p < 0.01) were observed in the penumbra region in AUDA-treated rats (N = 5 for each group). These results suggested that AUDA affects the anti-inflammation at the beginning of ischemic injury and restores neuronal metabolic rate of O2 and tissue viability. The neovascularization triggered by AUDA restored CBF and may contribute to ischemic infarction reduction at post-stroke day 3. Moreover, for long-term neuroprotection, astrocytes in the penumbra region may play an important role in protecting neurons from apoptotic injury.
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Affiliation(s)
- Han-Lin Wang
- Department of Biomedical Engineering, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Jia-Wei Chen
- Department of Biomedical Engineering, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Shih-Hung Yang
- Department of Mechanical Engineering, National Cheng Kung University, Tainan, Taiwan
| | - Yu-Chun Lo
- The Ph.D. Program for Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan
| | - Han-Chi Pan
- National Laboratory Animal Center, Taipei, Taiwan
| | - Yao-Wen Liang
- Department of Biomedical Engineering, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Ching-Fu Wang
- Department of Biomedical Engineering, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Yi Yang
- Department of Biomedical Engineering, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Yun-Ting Kuo
- Department of Biomedical Engineering, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Yi-Chen Lin
- Department of Biomedical Engineering, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Chin-Yu Chou
- Department of Biomedical Engineering, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Sheng-Huang Lin
- Department of Neurology, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan.,Department of Neurology, School of Medicine, Tzu Chi University, Hualien, Taiwan
| | - You-Yin Chen
- Department of Biomedical Engineering, National Yang Ming Chiao Tung University, Taipei, Taiwan.,The Ph.D. Program for Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan
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10
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Wang X, Luo Y, Chen Y, Chen C, Yin L, Yu T, He W, Ma C. A Skull-Removed Chronic Cranial Window for Ultrasound and Photoacoustic Imaging of the Rodent Brain. Front Neurosci 2021; 15:673740. [PMID: 34135729 PMCID: PMC8200560 DOI: 10.3389/fnins.2021.673740] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 05/06/2021] [Indexed: 11/13/2022] Open
Abstract
Ultrasound and photoacoustic imaging are emerging as powerful tools to study brain structures and functions. The skull introduces significant distortion and attenuation of the ultrasound signals deteriorating image quality. For biological studies employing rodents, craniotomy is often times performed to enhance image qualities. However, craniotomy is unsuitable for longitudinal studies, where a long-term cranial window is needed to prevent repeated surgeries. Here, we propose a mouse model to eliminate sound blockage by the top portion of the skull, while minimum physiological perturbation to the imaged object is incurred. With the new mouse model, no craniotomy is needed before each imaging experiment. The effectiveness of our method was confirmed by three imaging systems: photoacoustic computed tomography, ultrasound imaging, and photoacoustic mesoscopy. Functional photoacoustic imaging of the mouse brain hemodynamics was also conducted. We expect new applications to be enabled by the new mouse model for photoacoustic and ultrasound imaging.
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Affiliation(s)
- Xuanhao Wang
- Department of Electronic Engineering, Tsinghua University, Beijing, China
| | - Yan Luo
- Department of Electronic Engineering, Tsinghua University, Beijing, China
| | - Yuwen Chen
- Department of Electronic Engineering, Tsinghua University, Beijing, China
| | - Chaoyi Chen
- Department of Electronic Engineering, Tsinghua University, Beijing, China
| | - Lu Yin
- Department of Ultrasound, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Tengfei Yu
- Department of Ultrasound, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Wen He
- Department of Ultrasound, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Cheng Ma
- Department of Electronic Engineering, Tsinghua University, Beijing, China.,Beijing National Research Center for Information Science and Technology, Beijing, China.,Beijing Innovation Center for Future Chip, Beijing, China
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11
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Li DY, Zheng Z, Yu TT, Tang BZ, Fei P, Qian J, Zhu D. Visible-near infrared-II skull optical clearing window for in vivo cortical vasculature imaging and targeted manipulation. J Biophotonics 2020; 13:e202000142. [PMID: 32589789 DOI: 10.1002/jbio.202000142] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 05/27/2020] [Accepted: 06/16/2020] [Indexed: 06/11/2023]
Abstract
Skull optical clearing window permits us to perform in vivo cortical imaging without craniotomy, but mainly limits to visible (vis)-near infrared (NIR)-I light imaging. If the skull optical clearing window is available for NIR-II, the imaging depth will be further enhanced. Herein, we developed a vis-NIR-II skull optical clearing agents with deuterium oxide instead of water, which could make the skull transparent in the range of visible to NIR-II. Using a NIR-II excited third harmonic generation microscope, the cortical vasculature of mice could be clearly distinguished even at the depth of 650 μm through the vis-NIR-II skull clearing window. The imaging depth after clearing is close to that without skull, and increases by three times through turbid skull. Furthermore, the new skull optical clearing window promises to realize NIR-II laser-induced targeted injury of cortical single vessel. This work enhances the ability of NIR-II excited nonlinear imaging techniques for accessing to cortical neurovasculature in deep tissue.
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Affiliation(s)
- Dong-Yu Li
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei, China
- State Key Laboratory of Modern Optical Instrumentations, Centre for Optical and Electromagnetic Research, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou, China
- MoE Key Laboratory for Biomedical Photonics, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Zheng Zheng
- Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction Division of Life Science, State Key Laboratory of Molecular Neuroscience, Institute for Advanced Study, Institute of Molecular Functional Materials, Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Kowloon, Hong Kong
| | - Ting-Ting Yu
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei, China
- MoE Key Laboratory for Biomedical Photonics, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Ben-Zhong Tang
- Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction Division of Life Science, State Key Laboratory of Molecular Neuroscience, Institute for Advanced Study, Institute of Molecular Functional Materials, Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Kowloon, Hong Kong
| | - Peng Fei
- School of Optical and Electronic Information-Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, China
| | - Jun Qian
- State Key Laboratory of Modern Optical Instrumentations, Centre for Optical and Electromagnetic Research, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou, China
| | - Dan Zhu
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei, China
- MoE Key Laboratory for Biomedical Photonics, Huazhong University of Science and Technology, Wuhan, Hubei, China
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12
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Parfenova H, Liu J, Hoover DT, Fedinec AL. Vasodilator effects of sulforaphane in cerebral circulation: A critical role of endogenously produced hydrogen sulfide and arteriolar smooth muscle K ATP and BK channels in the brain. J Cereb Blood Flow Metab 2020; 40:1987-1996. [PMID: 31594422 PMCID: PMC7786849 DOI: 10.1177/0271678x19878284] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
We investigated the effects of sulforaphane (SFN), an isothiocyanate from cruciferous vegetables, in the regulation of cerebral blood flow using cranial windows in newborn pigs. SFN administered topically (10 µM-1 mM) or systemically (0.4 mg/kg ip) caused immediate and sustained dilation of pial arterioles concomitantly with elevated H2S in periarachnoid cortical cerebrospinal fluid. H2S is a potent vasodilator of cerebral arterioles. SFN is not a H2S donor but it acts via stimulating H2S generation in the brain catalyzed by cystathionine γ-lyase (CSE) and cystathionine β-synthase (CBS). CSE/CBS inhibitors propargylglycine, β-cyano-L-alanine, and aminooxyacetic acid blocked brain H2S generation and cerebral vasodilation caused by SFN. The SFN-elicited vasodilation requires activation of potassium channels in cerebral arterioles. The inhibitors of KATP and BK channels glibenclamide, paxilline, and iberiotoxin blocked the vasodilator effects of topical and systemic SFN, supporting the concept that H2S is the mediator of the vasodilator properties of SFN in cerebral circulation. Overall, we provide first evidence that SFN is a brain permeable compound that increases cerebral blood flow via a non-genomic mechanism that is mediated via activation of CSE/CBS-catalyzed H2S formation in neurovascular cells followed by H2S-induced activation of KATP and BK channels in arteriolar smooth muscle.
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Affiliation(s)
- Helena Parfenova
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Jianxiong Liu
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Daniel T Hoover
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Alex L Fedinec
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN, USA
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13
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Bayerl SH, Ghori A, Nieminen-Kelhä M, Adage T, Breitenbach J, Vajkoczy P, Prinz V. In vitro and in vivo testing of a novel local nicardipine delivery system to the brain: a preclinical study. J Neurosurg 2020; 132:465-472. [PMID: 30684943 DOI: 10.3171/2018.9.jns173085] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 09/20/2018] [Indexed: 11/06/2022]
Abstract
OBJECTIVE The management of patients with aneurysmal subarachnoid hemorrhage (aSAH) remains a highly demanding challenge in critical care medicine. Despite all efforts, the calcium channel antagonist nimodipine remains the only drug approved for improving outcomes after aSAH. However, in its current form of application, it provides less than optimal efficacy and causes dose-limiting hypotension in a substantial number of patients. Here, the authors tested in vitro the release dynamics of a novel formulation of the calcium channel blocker nicardipine and in vivo local tolerance and tissue reaction using a chronic cranial window model in mice. METHODS To characterize the release kinetics in vitro, dissolution experiments were performed using artificial cerebrospinal fluid over a time period of 21 days. The excipients used in this formulation (NicaPlant) for sustained nicardipine release are a mixture of two completely degradable polymers. A chronic cranial window in C57BL/6 mice was prepared, and NicaPlant slices were placed in proximity to the exposed cerebral vasculature. Epifluorescence video microscopy was performed right after implantation and on days 3 and 7 after surgery. Vessel diameter of the arteries and veins, vessel permeability, vessel configuration, and leukocyte-endothelial cell interaction were quantified by computer-assisted analysis. Immunofluorescence staining was performed to analyze inflammatory reactions and neuronal alterations. RESULTS In vitro the nicardipine release profile showed an almost linear curve with about 80% release at day 15 and full release at day 21. In vivo epifluorescence video microscopy showed a significantly higher arterial vessel diameter in the NicaPlant group due to vessel dilatation (21.6 ± 2.6 µm vs 17.8 ± 1.5 µm in controls, p < 0.01) confirming vasoactivity of the implant, whereas the venous diameter was not affected. Vessel dilatation did not have any influence on the vessel permeability measured by contrast extravasation of the fluorescent dye in epifluorescence microscopy. Further, an increased leukocyte-endothelial cell interaction due to the implant could not be detected. Histological analysis did not show any microglial activation or accumulation. No structural neuronal changes were observed. CONCLUSIONS NicaPlant provides continuous in vitro release of nicardipine over a 3-week observation period. In vivo testing confirmed vasoactivity and lack of toxicity. The local application of this novel nicardipine delivery system to the subarachnoid space is a promising tool to improve patient outcomes while avoiding systemic side effects.
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Affiliation(s)
- Simon H Bayerl
- 1Department of Neurosurgery and Center for Stroke-research Berlin (CSB), Charité-Universitätsmedizin Berlin, Germany; and
| | - Adnan Ghori
- 1Department of Neurosurgery and Center for Stroke-research Berlin (CSB), Charité-Universitätsmedizin Berlin, Germany; and
| | - Melina Nieminen-Kelhä
- 1Department of Neurosurgery and Center for Stroke-research Berlin (CSB), Charité-Universitätsmedizin Berlin, Germany; and
| | - Tiziana Adage
- 2Brain Implant Therapeutic (BIT) Pharma, Graz, Austria
| | | | - Peter Vajkoczy
- 1Department of Neurosurgery and Center for Stroke-research Berlin (CSB), Charité-Universitätsmedizin Berlin, Germany; and
| | - Vincent Prinz
- 1Department of Neurosurgery and Center for Stroke-research Berlin (CSB), Charité-Universitätsmedizin Berlin, Germany; and
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14
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Prada F, Franzini A, Moosa S, Padilla F, Moore D, Solbiati L, DiMeco F, Legon W. In vitro and in vivo characterization of a cranial window prosthesis for diagnostic and therapeutic cerebral ultrasound. J Neurosurg 2020; 134:646-658. [PMID: 31899872 DOI: 10.3171/2019.10.jns191674] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2019] [Accepted: 10/28/2019] [Indexed: 11/06/2022]
Abstract
OBJECTIVE The authors evaluated the acoustic properties of an implantable, biocompatible, polyolefin-based cranial prosthesis as a medium to transmit ultrasound energy into the intracranial space with minimal distortion for imaging and therapeutic purposes. METHODS The authors performed in vitro and in vivo studies of ultrasound transmission through a cranial prosthesis. In the in vitro phase, they analyzed the transmission of ultrasound energy through the prosthesis in a water tank using various transducers with resonance frequencies corresponding to those of devices used for neurosurgical imaging and therapeutic purposes. Four distinct, single-element, focused transducers were tested at fundamental frequencies of 500 kHz, 1 MHz, 2.5 MHz, and 5 MHz. In addition, the authors tested ultrasound transmission through the prosthesis using a linear diagnostic probe (center frequency 5.3 MHz) with a calibrated needle hydrophone in free water. Each transducer was assessed across a range of input voltages that encompassed their full minimum to maximum range without waveform distortion. They also tested the effect of the prosthesis on beam pressure and geometry. In the in vivo phase, the authors performed ultrasound imaging through the prosthesis implanted in a swine model. RESULTS Acoustic power attenuation through the prosthesis was considerably lower than that reported to occur through the native cranial bone. Increasing the frequency of the transducer augmented the degree of acoustic power loss. The degradation/distortion of the ultrasound beams passing through the prosthesis was minimal in all 3 spatial planes (XY, XZ, and YZ) that were examined. The images acquired in vivo demonstrated no spatial distortion from the prosthesis, with spatial relationships that were superimposable to those acquired through the dura. CONCLUSIONS The results of the tests performed on the polyolefin-based cranial prosthesis indicated that this is a valid medium for delivering both focused and unfocused ultrasound and obtaining ultrasound images of the intracranial space. The prosthesis may serve for several diagnostic and therapeutic ultrasound-based applications, including bedside imaging of the brain and ultrasound-guided focused ultrasound cerebral procedures.
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Affiliation(s)
- Francesco Prada
- 1Department of Neurosurgery, Fondazione IRCCS Istituto Neurologico C. Besta, Milano, Italy
- 2Department of Neurosurgery, University of Virginia Health System
- 3Focused Ultrasound Foundation, Charlottesville, Virginia
| | - Andrea Franzini
- 1Department of Neurosurgery, Fondazione IRCCS Istituto Neurologico C. Besta, Milano, Italy
- 2Department of Neurosurgery, University of Virginia Health System
| | - Shayan Moosa
- 2Department of Neurosurgery, University of Virginia Health System
| | | | - David Moore
- 3Focused Ultrasound Foundation, Charlottesville, Virginia
| | - Luigi Solbiati
- 4Department of Radiology, Humanitas Research Hospital, Rozzano, Italy
| | - Francesco DiMeco
- 1Department of Neurosurgery, Fondazione IRCCS Istituto Neurologico C. Besta, Milano, Italy
- 5Department of Neurosurgery, Johns Hopkins University, Baltimore, Maryland; and
- 6Department of Pathophysiology and Transplantation, Università degli studi di Milano, Italy
| | - Wynn Legon
- 2Department of Neurosurgery, University of Virginia Health System
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15
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Solarana K, Ye M, Gao YR, Rafi H, Hammer DX. Longitudinal multimodal assessment of neurodegeneration and vascular remodeling correlated with signal degradation in chronic cortical silicon microelectrodes. Neurophotonics 2020; 7:015004. [PMID: 32042853 PMCID: PMC6991888 DOI: 10.1117/1.nph.7.1.015004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 01/14/2020] [Indexed: 05/19/2023]
Abstract
Significance: Cortically implanted microelectrode arrays provide a direct interface with neuronal populations and are used to restore movement capabilities and provide sensory feedback to patients with paralysis or amputation. Penetrating electrodes experience high rates of signal degradation within the first year that limit effectiveness and lead to eventual device failure. Aim: To assess vascular and neuronal changes over time in mice with implanted electrodes and examine the contribution of the brain tissue response to electrode performance. Approach: We used a multimodal approach combining in vivo electrophysiology and subcellular-level optical imaging. Results: At acute timescales, we observed structural damage from the mechanical trauma of electrode insertion, evidenced by severed dendrites in the electrode path and local hypofluorescence. Superficial vessel growth and remodeling occurred within the first few weeks in both electrode-implanted and window-only animals, but the deeper capillary growth evident in window-only animals was suppressed in electrode-implanted animals. After longer implantation periods, there was evidence of degeneration of transected dendrites superficial to the electrode path and localized neuronal cell body loss, along with deep vascular velocity changes near the electrode. Total spike rate (SR) across all animals reached a peak between 3 and 9 months postimplantation, then decreased. The local field potential signal remained relatively constant for up to 6 months, particularly in the high-gamma band, indicating long-term electrode viability and neuronal functioning at further distances from the electrode, but it showed a reduction in some animals at later time points. Most importantly, we found that progressive high-gamma and SR reductions both correlate positively with localized cell loss and decreasing capillary density within 100 μ m of the electrode. Conclusions: This multifaceted approach provided a more comprehensive picture of the ongoing biological response at the brain-electrode interface than can be achieved with postmortem histology alone and established a real-time relationship between electrophysiology and tissue damage.
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Affiliation(s)
- Krystyna Solarana
- Food and Drug Administration, Center for Radiological Devices, Office of Science and Engineering Laboratories, Division of Biomedical Physics, Silver Spring, Maryland, United States
| | - Meijun Ye
- Food and Drug Administration, Center for Radiological Devices, Office of Science and Engineering Laboratories, Division of Biomedical Physics, Silver Spring, Maryland, United States
| | - Yu-Rong Gao
- Food and Drug Administration, Center for Radiological Devices, Office of Science and Engineering Laboratories, Division of Biomedical Physics, Silver Spring, Maryland, United States
| | - Harmain Rafi
- Food and Drug Administration, Center for Radiological Devices, Office of Science and Engineering Laboratories, Division of Biomedical Physics, Silver Spring, Maryland, United States
| | - Daniel X. Hammer
- Food and Drug Administration, Center for Radiological Devices, Office of Science and Engineering Laboratories, Division of Biomedical Physics, Silver Spring, Maryland, United States
- Address all correspondence to Daniel X. Hammer, E-mail:
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Dolezyczek H, Tamborski S, Majka P, Sampson D, Wojtkowski M, Wilczyński G, Szkulmowski M, Malinowska M. In vivo brain imaging with multimodal optical coherence microscopy in a mouse model of thromboembolic photochemical stroke. Neurophotonics 2020; 7:015002. [PMID: 32016131 PMCID: PMC6977401 DOI: 10.1117/1.nph.7.1.015002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 12/19/2019] [Indexed: 06/10/2023]
Abstract
We used a new multimodal imaging system that combines optical coherence microscopy and brightfield microscopy. Using this in vivo brain monitoring approach and cranial window implantation, we three-dimensionally visualized the vascular network during thrombosis, with high temporal (18 s) and spatial (axial, 2.5 μ m ; lateral, 2.2 μ m ) resolution. We used a modified mouse model of photochemical thromboembolic stroke in order to more accurately parallel human stroke. Specifically, we applied green laser illumination to focally occlude a branch of the middle cerebral artery. Despite the recanalization of the superficial arteries at 24 h after stroke, no blood flow was detected in the small vessels within deeper regions. Moreover, after 24 h of stroke progression, scattering signal enhancement was observed within the stroke region. We also evaluated the infarct extent and shape histologically. In summary, we present a novel approach for real-time mouse brain monitoring and ischemic variability analysis. This multimodal imaging method permits the analysis of thrombosis progression and reperfusion. Additionally and importantly, the system could be used to study the effect of poststroke drug treatments on blood flow in small arteries and capillaries of the brain.
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Affiliation(s)
- Hubert Dolezyczek
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Szymon Tamborski
- Nicolaus Copernicus University, Institute of Physics, Faculty of Physics, Astronomy and Informatics, Torun, Poland
| | - Piotr Majka
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Danuta Sampson
- University of Surrey, Surrey Biophotonics, Centre for Vision, Speech and Signal Processing, School of Biosciences and Medicine, Guildford, United Kingdom
| | - Maciej Wojtkowski
- Institute of Physical Chemistry of the Polish Academy of Sciences, Warsaw, Poland
| | - Grzegorz Wilczyński
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Maciej Szkulmowski
- Nicolaus Copernicus University, Institute of Physics, Faculty of Physics, Astronomy and Informatics, Torun, Poland
| | - Monika Malinowska
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
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Park H, You N, Lee J, Suh M. Longitudinal study of hemodynamics and dendritic membrane potential changes in the mouse cortex following a soft cranial window installation. Neurophotonics 2019; 6:015006. [PMID: 30820438 PMCID: PMC6387987 DOI: 10.1117/1.nph.6.1.015006] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 01/25/2019] [Indexed: 05/21/2023]
Abstract
The soft cranial window using polydimethylsiloxane allows direct multiple access to neural tissue during long-term monitoring. However, the chronic effects of soft window installation on the brain have not been fully studied. Here, we investigate the long-term effects of soft window installation on sensory-evoked cerebral hemodynamics and neuronal activity. We monitored the brain tissue immunocytohistology for 6 weeks postinstallation. Heightened reactive astrocytic and microglia levels were found at 2 weeks postinstallation. By 6 weeks postinstallation, mice had expression levels similar to those of normal animals. We recorded sensory-evoked hemodynamics of the barrel cortex and LFP during whisker stimulation at these time points. Animals at 6 weeks postinstallation showed stronger hemodynamic responses and focalized barrel mapping than 2-week postoperative mice. LFP recordings of 6-week postoperative mice also showed higher neural activity at the barrel column corresponding to the stimulated whisker. Furthermore, the expression level of interleukin- 1 β was highly upregulated at 2 weeks postinstallation. When we treated animals postoperatively with minocycline plus N-acetylcystein, a drug-suppressing inflammatory cytokine, these animals did not show declined hemodynamic responses and neuronal activities. This result suggests that neuroinflammation following soft window installation may alter hemodynamic and neuronal responses upon sensory stimulation.
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Affiliation(s)
- Hyejin Park
- Institute for Basic Science, Center for Neuroscience Imaging Research, Suwon, Republic of Korea
- Sungkyunkwan University, Department of Biological Sciences, Suwon, Republic of Korea
- Sungkyunkwan University, Biomedical Institute for Convergence, Suwon, Republic of Korea
| | - Nayeon You
- Institute for Basic Science, Center for Neuroscience Imaging Research, Suwon, Republic of Korea
- Sungkyunkwan University, Department of Biomedical Engineering, Suwon, Republic of Korea
| | - Juheon Lee
- Institute for Basic Science, Center for Neuroscience Imaging Research, Suwon, Republic of Korea
- Sungkyunkwan University, Department of Biomedical Engineering, Suwon, Republic of Korea
| | - Minah Suh
- Institute for Basic Science, Center for Neuroscience Imaging Research, Suwon, Republic of Korea
- Sungkyunkwan University, Biomedical Institute for Convergence, Suwon, Republic of Korea
- Sungkyunkwan University, Department of Biomedical Engineering, Suwon, Republic of Korea
- Sungkyunkwan University, SAHIST, Suwon, Republic of Korea
- Address all correspondence to Minah Suh, E-mail:
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18
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Patel S, Fedinec AL, Liu J, Weiss MA, Pourcyrous M, Harsono M, Parfenova H, Leffler CW. H 2S mediates the vasodilator effect of endothelin-1 in the cerebral circulation. Am J Physiol Heart Circ Physiol 2018; 315:H1759-H1764. [PMID: 30265150 DOI: 10.1152/ajpheart.00451.2018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
H2S is an endogenous gasotransmitter that increases cerebral blood flow. In the cerebral vascular endothelium, H2S is produced by cystathionine δ-lyase (CSE). Endothelin-1 (ET-1) has constrictor and dilator influences on the cerebral circulation. The mechanism of the vasodilation caused by ET-1 may involve endothelium-derived factors. We hypothesize that ET-1-elicited dilation of pial arterioles requires an elevation of H2S production in the cerebral vascular endothelium. We investigated the effects of ET-1 on CSE-catalyzed brain H2S production and pial arteriolar diameter using cranial windows in newborn pigs in vivo. H2S was measured in periarachnoid cerebrospinal fluid. ET-1 (10-12-10-8 M) caused an elevation of H2S that was reduced by the CSE inhibitors propargylglycine (PPG) and β-cyano-l-alanine (BCA). Low doses of ET-1 (10-12-10-11 M) produced vasodilation of pial arterioles that was blocked PPG and BCA, suggesting the importance of H2S influences. The vasodilator effects of H2S may require activation of smooth muscle cell membrane ATP-sensitive K+ (KATP) channels and large-conductance Ca2+-activated K+ (BK) channels. The KATP inhibitor glibenclamide and the BK inhibitor paxilline blocked CSE/H2S-dependent dilation of pial arterioles to ET-1. In contrast, the vasoconstrictor response of pial arterioles to 10-8 M ET-1 was not modulated by PPG, BCA, glibenclamide, or paxilline and, therefore, was independent of CSE/H2S influences. Pial arteriolar constriction response to higher levels of ET-1 was independent of CSE/H2S and KATP/BKCa channel activation. These data suggest that H2S is an endothelium-derived factor that mediates the vasodilator effects of ET-1 in the cerebral circulation via a mechanism that involves activation of KATP and BK channels in vascular smooth muscle. NEW & NOTEWORTHY Disorders of the cerebral circulation in newborn infants may lead to lifelong neurological disabilities. We report that vasoactive peptide endothelin-1 exhibits vasodilator properties in the neonatal cerebral circulation by stimulating production of H2S, an endothelium-derived messenger with vasodilator properties. The ability of endothelin-1 to stimulate brain production of H2S may counteract the reduction in cerebral blood flow and prevent the cerebral vascular dysfunction caused by stroke, asphyxia, cerebral hypoxia, ischemia, and vasospasm.
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Affiliation(s)
- Shalinkumar Patel
- Division of Neonatology, Department of Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Alexander L Fedinec
- Laboratory for Research in Neonatal Physiology, Departments of Physiology and Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Jiangxiong Liu
- Laboratory for Research in Neonatal Physiology, Departments of Physiology and Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Max A Weiss
- Laboratory for Research in Neonatal Physiology, Departments of Physiology and Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Massroor Pourcyrous
- Division of Neonatology, Department of Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee.,Laboratory for Research in Neonatal Physiology, Departments of Physiology and Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Mimily Harsono
- Division of Neonatology, Department of Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Helena Parfenova
- Laboratory for Research in Neonatal Physiology, Departments of Physiology and Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Charles W Leffler
- Division of Neonatology, Department of Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee.,Laboratory for Research in Neonatal Physiology, Departments of Physiology and Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee
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19
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Abstract
Multiphoton intravital calcium imaging is a powerful technique that enables high-resolution longitudinal monitoring of cellular and subcellular activity hundreds of microns deep in the living organism. This unit addresses the application of 2-photon microscopy to imaging of genetically encoded calcium indicators (GECIs) in the mouse brain. The protocols in this unit enable real-time intravital imaging of intracellular calcium concentration simultaneously in hundreds of neurons, or at the resolution of single synapses, as mice respond to sensory stimuli or perform behavioral tasks. Protocols are presented for implantation of a cranial imaging window to provide optical access to the brain and for 2-photon image acquisition. Protocols for implantation of both open skull and thinned skull windows for single or multi-session imaging are described. © 2018 by John Wiley & Sons, Inc.
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Affiliation(s)
- Claire E J Cheetham
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania
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20
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Song J, Yang L, Nan D, He Q, Wan Y, Guo H. Histidine Alleviates Impairments Induced by Chronic Cerebral Hypoperfusion in Mice. Front Physiol 2018; 9:662. [PMID: 29930513 PMCID: PMC5999792 DOI: 10.3389/fphys.2018.00662] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Accepted: 05/14/2018] [Indexed: 12/16/2022] Open
Abstract
Chronic cerebral hypoperfusion is one of the fundamental pathological causes of brain disease such as vascular dementia. Exploration of effective treatments for this is of great interest. Histidine has been reported to be effective in anti-apoptosis, antioxidant, and against excitotoxicity. In the present study, we aim to investigate whether histidine could have a therapeutic effect on the impairments induced by chronic cerebral hypoperfusion. Cerebral hypoperfusion model was established through bilateral common carotid arteries stenosis (BCAS) operation in Tie2-GFP mice. Radial arm maze and Morris water maze revealed that histidine showed potential improvement of the tendency of cognitive impairments induced by hypoperfusion. The possible mechanisms were further investigated. After administration of histidine in hypoperfusion mice, immunofluorescent BrdU staining revealed more new-born nerve cells. In vivo observation through a cranial window under two-photon laser-scanning microscopy demonstrated that the blood flow velocity in capillary was improved, the distance between the astrocytes and the penetrating artery was shortened. Histidine administration also significantly increased the protein expression level of zonula occludens protein 1, an indicator of the integrity of blood–brain barrier (BBB). These results suggest that histidine could alleviate the impairments induced by chronic cerebral hypoperfusion in mice, and this effect may be related to the neurogenesis, astrocytes, and the integrity of the BBB.
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Affiliation(s)
- Jiangman Song
- Department of Neurology, People's Hospital, Peking University, Beijing, China
| | - Lu Yang
- Department of Neurology, People's Hospital, Peking University, Beijing, China
| | - Di Nan
- Department of Neurology, People's Hospital, Peking University, Beijing, China
| | - Qihua He
- Center of Medical and Health Analysis, Peking University, Beijing, China
| | - You Wan
- Key Laboratory for Neuroscience, Ministry of Education, National Health and Family Planning Commission, Peking University, Beijing, China
| | - Huailian Guo
- Department of Neurology, People's Hospital, Peking University, Beijing, China.,Key Laboratory for Neuroscience, Ministry of Education, National Health and Family Planning Commission, Peking University, Beijing, China
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21
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Zhao YJ, Yu TT, Zhang C, Li Z, Luo QM, Xu TH, Zhu D. Skull optical clearing window for in vivo imaging of the mouse cortex at synaptic resolution. Light Sci Appl 2018; 7:17153. [PMID: 30839532 PMCID: PMC6060065 DOI: 10.1038/lsa.2017.153] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 10/27/2017] [Accepted: 10/27/2017] [Indexed: 05/05/2023]
Abstract
Imaging cells and microvasculature in the living brain is crucial to understanding an array of neurobiological phenomena. Here, we introduce a skull optical clearing window for imaging cortical structures at synaptic resolution. Combined with two-photon microscopy, this technique allowed us to repeatedly image neurons, microglia and microvasculature of mice. We applied it to study the plasticity of dendritic spines in critical periods and to visualize dendrites and microglia after laser ablation. Given its easy handling and safety, this method holds great promise for application in neuroscience research.
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Affiliation(s)
- Yan-Jie Zhao
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan 430074, China
- MoE Key Laboratory for Biomedical Photonics, Collaborative Innovation Center for Biomedical Engineering, School of Engineering Sciences, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Ting-Ting Yu
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan 430074, China
- MoE Key Laboratory for Biomedical Photonics, Collaborative Innovation Center for Biomedical Engineering, School of Engineering Sciences, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Chao Zhang
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan 430074, China
- MoE Key Laboratory for Biomedical Photonics, Collaborative Innovation Center for Biomedical Engineering, School of Engineering Sciences, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Zhao Li
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan 430074, China
- MoE Key Laboratory for Biomedical Photonics, Collaborative Innovation Center for Biomedical Engineering, School of Engineering Sciences, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Qing-Ming Luo
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan 430074, China
- MoE Key Laboratory for Biomedical Photonics, Collaborative Innovation Center for Biomedical Engineering, School of Engineering Sciences, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Tong-Hui Xu
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan 430074, China
- MoE Key Laboratory for Biomedical Photonics, Collaborative Innovation Center for Biomedical Engineering, School of Engineering Sciences, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Dan Zhu
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan 430074, China
- MoE Key Laboratory for Biomedical Photonics, Collaborative Innovation Center for Biomedical Engineering, School of Engineering Sciences, Huazhong University of Science and Technology, Wuhan 430074, China
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22
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Voziyanov V, Kemp BS, Dressel CA, Ponder K, Murray TA. TRIO Platform: A Novel Low Profile In vivo Imaging Support and Restraint System for Mice. Front Neurosci 2016; 10:169. [PMID: 27199633 PMCID: PMC4842766 DOI: 10.3389/fnins.2016.00169] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 04/04/2016] [Indexed: 11/17/2022] Open
Abstract
High resolution, in vivo optical imaging of the mouse brain over time often requires anesthesia, which necessitates maintaining the animal's body temperature and level of anesthesia, as well as securing the head in an optimal, stable position. Controlling each parameter usually requires using multiple systems. Assembling multiple components into the small space on a standard microscope stage can be difficult and some commercially available parts simply do not fit. Furthermore, it is time-consuming to position an animal in the identical position over multiple imaging sessions for longitudinal studies. This is especially true when using an implanted gradient index (GRIN) lens for deep brain imaging. The multiphoton laser beam must be parallel with the shaft of the lens because even a slight tilt of the lens can degrade image quality. In response to these challenges, we have designed a compact, integrated in vivo imaging support system to overcome the problems created by using separate systems during optical imaging in mice. It is a single platform that provides (1) sturdy head fixation, (2) an integrated gas anesthesia mask, and (3) safe warm water heating. This THREE-IN-ONE (TRIO) Platform has a small footprint and a low profile that positions a mouse's head only 20 mm above the microscope stage. This height is about one half to one third the height of most commercially available immobilization devices. We have successfully employed this system, using isoflurane in over 40 imaging sessions with an average of 2 h per session with no leaks or other malfunctions. Due to its smaller size, the TRIO Platform can be used with a wider range of upright microscopes and stages. Most of the components were designed in SOLIDWORKS® and fabricated using a 3D printer. This additive manufacturing approach also readily permits size modifications for creating systems for other small animals.
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Affiliation(s)
- Vladislav Voziyanov
- Integrated Neuroscience and Imaging Lab, Center for Biomedical Engineering and Rehabilitation Sciences, Louisiana Tech UniversityRuston, LA, USA; School of Biological and Health Systems Engineering, Ira A. Fulton School of Engineering, Arizona State UniversityTempe, AZ, USA
| | - Benjamin S Kemp
- Integrated Neuroscience and Imaging Lab, Center for Biomedical Engineering and Rehabilitation Sciences, Louisiana Tech University Ruston, LA, USA
| | - Chelsea A Dressel
- Integrated Neuroscience and Imaging Lab, Center for Biomedical Engineering and Rehabilitation Sciences, Louisiana Tech University Ruston, LA, USA
| | - Kayla Ponder
- Integrated Neuroscience and Imaging Lab, Center for Biomedical Engineering and Rehabilitation Sciences, Louisiana Tech University Ruston, LA, USA
| | - Teresa A Murray
- Integrated Neuroscience and Imaging Lab, Center for Biomedical Engineering and Rehabilitation Sciences, Louisiana Tech University Ruston, LA, USA
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23
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Hammer DX, Lozzi A, Boretsky A, Welle CG. Acute insertion effects of penetrating cortical microelectrodes imaged with quantitative optical coherence angiography. Neurophotonics 2016; 3:025002. [PMID: 32064297 PMCID: PMC7011942 DOI: 10.1117/1.nph.3.2.025002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 03/16/2016] [Indexed: 05/16/2023]
Abstract
The vascular response during cortical microelectrode insertion was measured with amplitude decorrelation-based quantitative optical coherence angiography (OCA). Four different shank-style microelectrode configurations were inserted in murine motor cortex beneath a surgically implanted window in discrete steps while OCA images were collected and processed for angiography and flowmetry. Quantitative measurements included tissue displacement (measured by optical flow), perfused capillary density, and capillary flow velocity. The primary effect of insertion was mechanical perturbation, the effects of which included tissue displacement, arteriolar rupture, and compression of a branch of the anterior cerebral artery causing a global decrease in flow. Other effects observed included local flow drop-out in the region immediately surrounding the microelectrode. The mean basal capillary network velocity for all animals was 0.23 ( ± 0.05 SD ) and 0.18 ( ± 0.07 SD ) mm / s for capillaries from 100 to 300 μ m and 300 to 500 μ m , respectively. Upon insertion, the 2-shank electrode arrays caused a decrease in capillary flow density and velocity, while the results from other configurations were not different from controls. The proximity to large vessels appears to play a larger role than the array configuration. These results can guide neurosurgeons and electrode designers to minimize trauma and ischemia during microelectrode insertion.
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Affiliation(s)
- Daniel X. Hammer
- Center for Devices and Radiological Health, Food and Drug Administration, Division of Biomedical Physics, Office of Science and Engineering Laboratories, 20903 New Hampshire Avenue, Silver Spring, Maryland 20993, United States
- Address all correspondence to: Daniel X. Hammer, E-mail:
| | - Andrea Lozzi
- Center for Devices and Radiological Health, Food and Drug Administration, Division of Biomedical Physics, Office of Science and Engineering Laboratories, 20903 New Hampshire Avenue, Silver Spring, Maryland 20993, United States
| | - Adam Boretsky
- Center for Devices and Radiological Health, Food and Drug Administration, Division of Biomedical Physics, Office of Science and Engineering Laboratories, 20903 New Hampshire Avenue, Silver Spring, Maryland 20993, United States
| | - Cristin G. Welle
- Center for Devices and Radiological Health, Food and Drug Administration, Division of Biomedical Physics, Office of Science and Engineering Laboratories, 20903 New Hampshire Avenue, Silver Spring, Maryland 20993, United States
- University of Colorado Denver, Departments of Neurosurgery and Bioengineering, 12700 East 19th Avenue, Aurora, Colorado 80045, United States
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24
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Sharim J, Pezeshkian P, DeSalles A, Pouratian N. Effect of Cranial Window Diameter During Deep Brain Stimulation Surgery on Volume of Pneumocephalus. Neuromodulation 2015. [PMID: 26222380 DOI: 10.1111/ner.12328] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Successful deep brain stimulation (DBS) surgery necessitates high accuracy in targeting specific intracranial nuclei. Brain shift due to pneumocephalus can contribute to decreased accuracy. Larger burr holes and dural openings may increase pneumocephalus volume due to a greater degree of communication between the subdural space and extracranial air. The aim of this study is to determine if there is a statistically and clinically significant difference in postoperative pneumocephalus volume related to burr hole and durotomy size. MATERIALS AND METHODS DBS electrodes were surgically implanted through either large (14 mm) burr holes or small (4 mm) twist drill holes. Immediate postoperative computerized tomography (CT) scans of 165 electrode implantations in 85 patients from 2010 to 2013 were retrospectively analyzed. Student's t-test and Mann-Whitney U-test were employed with a threshold of significance set at p ≤ 0.05. RESULTS No significant difference in pneumocephalus was identified between patients who had implantation of DBS electrodes through 4 mm twist drill holes (N = 71 hemispheres, 12.84 ± 9.79 cm(3) ) and those with large 14 mm burr holes (N = 87, 11.70 ± 7.46 cm(3) , p = 0.42). Volume of pneumocephalus did not correlate with duration of surgery or patient age. The groups did not differ significantly with respect to other aspects of surgical implantation technique or surgical duration. CONCLUSION While identifying factors that may reduce pneumocephalus volume may be critical to improving stereotactic accuracy and targeting, the current results suggest that burr hole size may not alter the degree of brain shift.
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Affiliation(s)
- Justin Sharim
- Department of Neurosurgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Patrick Pezeshkian
- Department of Neurosurgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Antonio DeSalles
- Department of Neurosurgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Nader Pouratian
- Department of Neurosurgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
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25
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Reichenbach ZW, Li H, Gaughan JP, Elliott M, Tuma R. IV and IP administration of rhodamine in visualization of WBC-BBB interactions in cerebral vessels. Microsc Res Tech 2015. [PMID: 26207355 DOI: 10.1002/jemt.22552] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Epi-illuminescence intravital fluorescence microscopy has been employed to study leukocyte-endothelial interactions in a number of brain pathologies. Historically, dyes such as Rhodamine 6G have been injected intravenously. However, intravenous injections can predispose experimental animals to a multitude of complications and requires a high degree of technical skill. Here, we study the efficacy of injecting Rhodamine 6G into the peritoneum (IP) for the purpose of analyzing leukocyte-endothelial interactions through a cranial window during real time intravital microscopy. After examining the number of rolling and adherent leukocytes through a cranial window, we found no advantage to the intravenous injection (IV). Additionally, we tested blood from both routes of injection by flow cytometry to gain a very precise picture of the two methods. The two routes of administration failed to show any difference in the ability to detect cells. The study supports the notion that IP Rhodamine 6G works as efficaciously as IV and should be considered a viable alternative in experimental design for investigations employing intravital microscopy. Facilitated intravital studies will allow for more exploration into cerebral pathologies and allow for more rapid translation from the laboratory to the patient with less chance of experimental error from failed IV access.
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Affiliation(s)
- Zachary Wilmer Reichenbach
- Temple University School of Medicine, Center for Sustance Abuse Research, Philadelphia, Pennsylvania, 19140.,Department of Cellular and Molecular Physiology, Temple University School of Medicine, Philadelphia, Pennsylvania, 19140
| | - Hongbo Li
- Temple University School of Medicine, Center for Sustance Abuse Research, Philadelphia, Pennsylvania, 19140.,Department of Cellular and Molecular Physiology, Temple University School of Medicine, Philadelphia, Pennsylvania, 19140
| | - John P Gaughan
- Temple University School of Medicine, Biostatistics Consulting Center, Philadelphia, Pennsylvania, 19140
| | - Melanie Elliott
- Department Neurosurgery, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania, 19107
| | - Ronald Tuma
- Temple University School of Medicine, Center for Sustance Abuse Research, Philadelphia, Pennsylvania, 19140.,Department of Cellular and Molecular Physiology, Temple University School of Medicine, Philadelphia, Pennsylvania, 19140
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26
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Abstract
In vivo two-photon scanning fluorescence imaging is a powerful technique to observe physiological processes from the millimeter to the micron scale in the intact animal. In neuroscience research, a common approach is to install an acute cranial window and head bar to explore neocortical function under anesthesia before inflammation peaks from the surgery. However, there are few detailed acute protocols for head-restrained and fully awake animal imaging of the neurovascular unit during activity. This is because acutely performed awake experiments are typically untenable when the animal is naïve to the imaging apparatus. Here we detail a method that achieves acute, deep-tissue two-photon imaging of neocortical astrocytes and microvasculature in behaving mice. A week prior to experimentation, implantation of the head bar alone allows mice to train for head-immobilization on an easy-to-learn air-supported ball treadmill. Following just two brief familiarization sessions to the treadmill on separate days, an acute cranial window can subsequently be installed for immediate imaging. We demonstrate how running and whisking data can be captured simultaneously with two-photon fluorescence signals with acceptable movement artifacts during active motion. We also show possible applications of this technique by (1) monitoring dynamic changes to microvascular diameter and red blood cells in response to vibrissa sensory stimulation, (2) examining responses of the cerebral microcirculation to the systemic delivery of pharmacological agents using a tail artery cannula during awake imaging, and (3) measuring Ca(2+) signals from synthetic and genetically encoded Ca(2+) indicators in astrocytes. This method will facilitate acute two-photon fluorescence imaging in awake, active mice and help link cellular events within the neurovascular unit to behavior.
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Affiliation(s)
- Cam Ha T Tran
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary Calgary, AB, Canada
| | - Grant R Gordon
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary Calgary, AB, Canada
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27
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Crowe SE, Ellis-Davies GCR. Longitudinal in vivo two-photon fluorescence imaging. J Comp Neurol 2014; 522:1708-27. [PMID: 24214350 DOI: 10.1002/cne.23502] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Revised: 10/15/2013] [Accepted: 10/15/2013] [Indexed: 12/29/2022]
Abstract
Fluorescence microscopy is an essential technique for the basic sciences, especially biomedical research. Since the invention of laser scanning confocal microscopy in the 1980s, which enabled imaging both fixed and living biological tissue with 3D precision, high-resolution fluorescence imaging has revolutionized biological research. Confocal microscopy, by its very nature, has one fundamental limitation. Due to the confocal pinhole, deep tissue fluorescence imaging is not practical. In contrast (no pun intended), two-photon fluorescence microscopy allows, in principle, the collection of all emitted photons from fluorophores in the imaged voxel, dramatically extending our ability to see deep into living tissue. Since the development of transgenic mice with genetically encoded fluorescent protein in neocortical cells in 2000, two-photon imaging has enabled the dynamics of individual synapses to be followed for up to 2 years. Since the initial landmark contributions to this field in 2002, the technique has been used to understand how neuronal structure are changed by experience, learning, and memory and various diseases. Here we provide a basic summary of the crucial elements that are required for such studies, and discuss many applications of longitudinal two-photon fluorescence microscopy that have appeared since 2002.
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Affiliation(s)
- Sarah E Crowe
- Department of Neuroscience, Mount Sinai School of Medicine, New York, NY, 10029
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28
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Dorand RD, Barkauskas DS, Evans TA, Petrosiute A, Huang AY. Comparison of intravital thinned skull and cranial window approaches to study CNS immunobiology in the mouse cortex. Intravital 2014; 3:e29728. [PMID: 25568834 PMCID: PMC4283137 DOI: 10.4161/intv.29728] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2014] [Revised: 06/06/2014] [Accepted: 06/25/2014] [Indexed: 01/11/2023]
Abstract
Fluorescent imaging coupled with high-resolution femto-second pulsed infrared lasers allows for interrogation of cellular interactions deeper in living tissues than ever imagined. Intra-vital imaging of the central nervous system (CNS) has provided insights into neuronal development, synaptic transmission, and even immune interactions. In this review we will discuss the two most common intravital approaches for studying the cerebral cortex in the live mouse brain for pre-clinical studies, the thinned skull and cranial window techniques, and focus on the advantages and drawbacks of each approach. In addition, we will discuss the use of neuronal physiologic parameters as determinants of successful surgical and imaging preparation.
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Affiliation(s)
- R Dixon Dorand
- Department of Pathology; Case Western Reserve University School of Medicine; Cleveland, Ohio USA
| | - Deborah S Barkauskas
- Department of Biomedical Engineering; Case Western Reserve University School of Medicine; Cleveland, Ohio USA
| | - Teresa A Evans
- Department of Neurosciences; Case Western Reserve University School of Medicine; Cleveland, Ohio USA
| | - Agne Petrosiute
- Department of Pediatrics; Case Western Reserve University School of Medicine; Cleveland, Ohio USA
| | - Alex Y Huang
- Department of Pathology; Case Western Reserve University School of Medicine; Cleveland, Ohio USA
- Department of Biomedical Engineering; Case Western Reserve University School of Medicine; Cleveland, Ohio USA
- Department of Pediatrics; Case Western Reserve University School of Medicine; Cleveland, Ohio USA
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29
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Ricard C, Debarbieux FC. Six-color intravital two-photon imaging of brain tumors and their dynamic microenvironment. Front Cell Neurosci 2014; 8:57. [PMID: 24605087 PMCID: PMC3932518 DOI: 10.3389/fncel.2014.00057] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Accepted: 02/06/2014] [Indexed: 11/13/2022] Open
Abstract
The majority of intravital studies on brain tumor in living animal so far rely on dual color imaging. We describe here a multiphoton imaging protocol to dynamically characterize the interactions between six cellular components in a living mouse. We applied this methodology to a clinically relevant glioblastoma multiforme (GBM) model designed in reporter mice with targeted cell populations labeled by fluorescent proteins of different colors. This model permitted us to make non-invasive longitudinal and multi-scale observations of cell-to-cell interactions. We provide examples of such 5D (x,y,z,t,color) images acquired on a daily basis from volumes of interest, covering most of the mouse parietal cortex at subcellular resolution. Spectral deconvolution allowed us to accurately separate each cell population as well as some components of the extracellular matrix. The technique represents a powerful tool for investigating how tumor progression is influenced by the interactions of tumor cells with host cells and the extracellular matrix micro-environment. It will be especially valuable for evaluating neuro-oncological drug efficacy and target specificity. The imaging protocol provided here can be easily translated to other mouse models of neuropathologies, and should also be of fundamental interest for investigations in other areas of systems biology.
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Affiliation(s)
- Clément Ricard
- Institut de Biologie du Développement de Marseille-Luminy, CNRS UMR7288 and Aix-Marseille Université Marseille, France ; Centre Européen de Recherche en Imagerie Médicale, Aix-Marseille Université Marseille, France ; Institut des Neurosciences de la Timone, CNRS UMR7289 and Aix-Marseille Université Marseille, France
| | - Franck Christian Debarbieux
- Institut de Biologie du Développement de Marseille-Luminy, CNRS UMR7288 and Aix-Marseille Université Marseille, France ; Centre Européen de Recherche en Imagerie Médicale, Aix-Marseille Université Marseille, France ; Institut des Neurosciences de la Timone, CNRS UMR7289 and Aix-Marseille Université Marseille, France
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30
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Masamoto K, Takuwa H, Seki C, Taniguchi J, Itoh Y, Tomita Y, Toriumi H, Unekawa M, Kawaguchi H, Ito H, Suzuki N, Kanno I. Microvascular sprouting, extension, and creation of new capillary connections with adaptation of the neighboring astrocytes in adult mouse cortex under chronic hypoxia. J Cereb Blood Flow Metab 2014; 34:325-31. [PMID: 24252848 PMCID: PMC3915210 DOI: 10.1038/jcbfm.2013.201] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 10/16/2013] [Accepted: 10/23/2013] [Indexed: 11/09/2022]
Abstract
The present study aimed to determine the spatiotemporal dynamics of microvascular and astrocytic adaptation during hypoxia-induced cerebral angiogenesis. Adult C57BL/6J and Tie2-green fluorescent protein (GFP) mice with vascular endothelial cells expressing GFP were exposed to normobaric hypoxia for 3 weeks, whereas the three-dimensional microvessels and astrocytes were imaged repeatedly using two-photon microscopy. After 7 to 14 days of hypoxia, a vessel sprout appeared from the capillaries with a bump-like head shape (mean diameter 14 μm), and stagnant blood cells were seen inside the sprout. However, no detectable changes in the astrocyte morphology were observed for this early phase of the hypoxia adaptation. More than 50% of the sprouts emerged from capillaries 60 μm away from the center penetrating arteries, which indicates that the capillary distant from the penetrating arteries is a favored site for sprouting. After 14 to 21 days of hypoxia, the sprouting vessels created a new connection with an existing capillary. In this phase, the shape of the new vessel and its blood flow were normalized, and the outside of the vessels were wrapped with numerous processes from the neighboring astrocytes. The findings indicate that hypoxia-induced cerebral angiogenesis provokes the adaptation of neighboring astrocytes, which may stabilize the blood-brain barrier in immature vessels.
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Affiliation(s)
- Kazuto Masamoto
- 1] Brain Science Inspired Life Support Research Center, University of Electro-Communications, Chofu, Tokyo, Japan [2] Molecular Imaging Center, National Institute of Radiological Sciences, Inage, Chiba, Japan
| | - Hiroyuki Takuwa
- Molecular Imaging Center, National Institute of Radiological Sciences, Inage, Chiba, Japan
| | - Chie Seki
- Molecular Imaging Center, National Institute of Radiological Sciences, Inage, Chiba, Japan
| | - Junko Taniguchi
- Molecular Imaging Center, National Institute of Radiological Sciences, Inage, Chiba, Japan
| | - Yoshiaki Itoh
- Department of Neurology, School of Medicine Keio University, Shinjuku, Tokyo, Japan
| | - Yutaka Tomita
- Department of Neurology, School of Medicine Keio University, Shinjuku, Tokyo, Japan
| | - Haruki Toriumi
- Department of Neurology, School of Medicine Keio University, Shinjuku, Tokyo, Japan
| | - Miyuki Unekawa
- Department of Neurology, School of Medicine Keio University, Shinjuku, Tokyo, Japan
| | - Hiroshi Kawaguchi
- Molecular Imaging Center, National Institute of Radiological Sciences, Inage, Chiba, Japan
| | - Hiroshi Ito
- Molecular Imaging Center, National Institute of Radiological Sciences, Inage, Chiba, Japan
| | - Norihiro Suzuki
- Department of Neurology, School of Medicine Keio University, Shinjuku, Tokyo, Japan
| | - Iwao Kanno
- Molecular Imaging Center, National Institute of Radiological Sciences, Inage, Chiba, Japan
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31
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Stetter C, Hirschberg M, Nieswandt B, Ernestus RI, Heckmann M, Sirén AL. An experimental protocol for in vivo imaging of neuronal structural plasticity with 2-photon microscopy in mice. Exp Transl Stroke Med 2013; 5:9. [PMID: 23842538 PMCID: PMC3716956 DOI: 10.1186/2040-7378-5-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 07/09/2013] [Indexed: 06/02/2023]
Abstract
INTRODUCTION Structural plasticity with synapse formation and elimination is a key component of memory capacity and may be critical for functional recovery after brain injury. Here we describe in detail two surgical techniques to create a cranial window in mice and show crucial points in the procedure for long-term repeated in vivo imaging of synaptic structural plasticity in the mouse neocortex. METHODS Transgenic Thy1-YFP(H) mice expressing yellow-fluorescent protein (YFP) in layer-5 pyramidal neurons were prepared under anesthesia for in vivo imaging of dendritic spines in the parietal cortex either with an open-skull glass or thinned skull window. After a recovery period of 14 days, imaging sessions of 45-60 min in duration were started under fluothane anesthesia. To reduce respiration-induced movement artifacts, the skull was glued to a stainless steel plate fixed to metal base. The animals were set under a two-photon microscope with multifocal scanhead splitter (TriMScope, LaVision BioTec) and the Ti-sapphire laser was tuned to the optimal excitation wavelength for YFP (890 nm). Images were acquired by using a 20×, 0.95 NA, water-immersion objective (Olympus) in imaging depth of 100-200 μm from the pial surface. Two-dimensional projections of three-dimensional image stacks containing dendritic segments of interest were saved for further analysis. At the end of the last imaging session, the mice were decapitated and the brains removed for histological analysis. RESULTS Repeated in vivo imaging of dendritic spines of the layer-5 pyramidal neurons was successful using both open-skull glass and thinned skull windows. Both window techniques were associated with low phototoxicity after repeated sessions of imaging. CONCLUSIONS Repeated imaging of dendritic spines in vivo allows monitoring of long-term structural dynamics of synapses. When carefully controlled for influence of repeated anesthesia and phototoxicity, the method will be suitable to study changes in synaptic structural plasticity after brain injury.
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Affiliation(s)
- Christian Stetter
- Department of Neurosurgery, University of Würzburg, Josef-Schneider-Str. 11, 97080 Würzburg, Germany
| | | | | | - Ralf-Ingo Ernestus
- Department of Neurosurgery, University of Würzburg, Josef-Schneider-Str. 11, 97080 Würzburg, Germany
| | - Manfred Heckmann
- Institute for Neurophysiology, University of Würzburg, Würzburg, Germany
| | - Anna-Leena Sirén
- Department of Neurosurgery, University of Würzburg, Josef-Schneider-Str. 11, 97080 Würzburg, Germany
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Pérez-Alvarez A, Araque A, Martín ED. Confocal microscopy for astrocyte in vivo imaging: Recycle and reuse in microscopy. Front Cell Neurosci 2013; 7:51. [PMID: 23658537 PMCID: PMC3647290 DOI: 10.3389/fncel.2013.00051] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Accepted: 04/07/2013] [Indexed: 02/01/2023] Open
Abstract
In vivo imaging is one of the ultimate and fundamental approaches for the study of the brain. Two-photon laser scanning microscopy (2PLSM) constitutes the state-of-the-art technique in current neuroscience to address questions regarding brain cell structure, development and function, blood flow regulation and metabolism. This technique evolved from laser scanning confocal microscopy (LSCM), which impacted the field with a major improvement in image resolution of live tissues in the 1980s compared to widefield microscopy. While nowadays some of the unparalleled features of 2PLSM make it the tool of choice for brain studies in vivo, such as the possibility to image deep within a tissue, LSCM can still be useful in this matter. Here we discuss the validity and limitations of LSCM and provide a guide to perform high-resolution in vivo imaging of the brain of live rodents with minimal mechanical disruption employing LSCM. We describe the surgical procedure and experimental setup that allowed us to record intracellular calcium variations in astrocytes evoked by sensory stimulation, and to monitor intact neuronal dendritic spines and astrocytic processes as well as blood vessel dynamics. Therefore, in spite of certain limitations that need to be carefully considered, LSCM constitutes a useful, convenient, and affordable tool for brain studies in vivo.
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Shih AY, Driscoll JD, Drew PJ, Nishimura N, Schaffer CB, Kleinfeld D. Two-photon microscopy as a tool to study blood flow and neurovascular coupling in the rodent brain. J Cereb Blood Flow Metab 2012; 32:1277-309. [PMID: 22293983 PMCID: PMC3390800 DOI: 10.1038/jcbfm.2011.196] [Citation(s) in RCA: 295] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2011] [Revised: 10/18/2011] [Accepted: 11/13/2011] [Indexed: 01/09/2023]
Abstract
The cerebral vascular system services the constant demand for energy during neuronal activity in the brain. Attempts to delineate the logic of neurovascular coupling have been greatly aided by the advent of two-photon laser scanning microscopy to image both blood flow and the activity of individual cells below the surface of the brain. Here we provide a technical guide to imaging cerebral blood flow in rodents. We describe in detail the surgical procedures required to generate cranial windows for optical access to the cortex of both rats and mice and the use of two-photon microscopy to accurately measure blood flow in individual cortical vessels concurrent with local cellular activity. We further provide examples on how these techniques can be applied to the study of local blood flow regulation and vascular pathologies such as small-scale stroke.
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Affiliation(s)
- Andy Y Shih
- Department of Physics, University of California at San Diego, La Jolla, California, USA
| | - Jonathan D Driscoll
- Department of Physics, University of California at San Diego, La Jolla, California, USA
| | - Patrick J Drew
- Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, Pennsylvania, USA
- Department of Neurosurgery, Pennsylvania State University, University Park, Pennsylvania, USA
| | - Nozomi Nishimura
- Department of Biomedical Engineering, Cornell University, Ithaca, New York, USA
| | - Chris B Schaffer
- Department of Biomedical Engineering, Cornell University, Ithaca, New York, USA
| | - David Kleinfeld
- Department of Physics, University of California at San Diego, La Jolla, California, USA
- Section of Neurobiology, University of California at San Diego, La Jolla, California, USA
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Abstract
Angiogenesis and microcirculation play a central role in growth and metastasis of human neoplasms, and, thus, represent a major target for novel treatment strategies. Mechanistic analysis of processes involved in tumor vascularization, however, requires sophisticated in vivo experimental models and techniques. Intravital microscopy allows direct assessment of tumor angiogenesis, microcirculation and overall perfusion. Its application to the study of tumor-induced neovascularization further provides information on molecular transport and delivery, intra- and extravascular cell-to-cell and cell-to-matrix interaction, as well as tumor oxygenation and metabolism. With the recent advances in the field of bioluminescence and fluorescent reporter genes, appropriate for in vivo imaging, the intravital fluorescent microscopic approach has to be considered a powerful tool to study microvascular, cellular and molecular mechanisms of tumor growth.
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Affiliation(s)
- P Vajkoczy
- Department of Neurosurgery, Klinikum Mannheim, University of Heidelberg, Mannheim, Germany.
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