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Yeon C, Im JM, Kim M, Kim YR, Chung E. Cranial and Spinal Window Preparation for in vivo Optical Neuroimaging in Rodents and Related Experimental Techniques. Exp Neurobiol 2022; 31:131-146. [PMID: 35786637 PMCID: PMC9272117 DOI: 10.5607/en22015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 06/03/2022] [Accepted: 06/15/2022] [Indexed: 11/19/2022] Open
Abstract
Optical neuroimaging provides an effective neuroscience tool for multi-scale investigation of the neural structures and functions, ranging from molecular, cellular activities to the inter-regional connectivity assessment. Amongst experimental preparations, the implementation of an artificial window to the central nervous system (CNS) is primarily required for optical visualization of the CNS and associated brain activities through the opaque skin and bone. Either thinning down or removing portions of the skull or spine is necessary for unobstructed long-term in vivo observations, for which types of the cranial and spinal window and applied materials vary depending on the study objectives. As diversely useful, a window can be designed to accommodate other experimental methods such as electrophysiology or optogenetics. Moreover, auxiliary apparatuses would allow the recording in synchrony with behavior of large-scale brain connectivity signals across the CNS, such as olfactory bulb, cerebral cortex, cerebellum, and spinal cord. Such advancements in the cranial and spinal window have resulted in a paradigm shift in neuroscience, enabling in vivo investigation of the brain function and dysfunction at the microscopic, cellular level. This Review addresses the types and classifications of windows used in optical neuroimaging while describing how to perform in vivo studies using rodent models in combination with other experimental modalities during behavioral tests. The cranial and spinal window has enabled longitudinal examination of evolving neural mechanisms via in situ visualization of the brain. We expect transformable and multi-functional cranial and spinal windows to become commonplace in neuroscience laboratories, further facilitating advances in optical neuroimaging systems.
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Affiliation(s)
- Chanmi Yeon
- Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 61005, Korea
| | - Jeong Myo Im
- Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 61005, Korea
| | - Minsung Kim
- Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 61005, Korea
| | - Young Ro Kim
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA 02129, USA.,Department of Radiology, Harvard Medical School, Boston, MA 02115, USA
| | - Euiheon Chung
- Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 61005, Korea.,AI Graduate School, Gwangju Institute of Science and Technology, Gwangju 61005, Korea.,Research Center for Photon Science Technology, Gwangju Institute of Science and Technology, Gwangju 61005, Korea
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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 APPLIED BIO MATERIALS 2022; 5:2664-2675. [PMID: 35671525 DOI: 10.1021/acsabm.2c00119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [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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Cano-Velázquez MS, Bon J, Llamazares M, Camacho-López S, Aguilar G, Hernández-Cordero J, Trujillo M. Experimental and computational model approach to assess the photothermal effects in transparent nanocrystalline yttria stabilized zirconia cranial implant. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2022; 221:106896. [PMID: 35617809 DOI: 10.1016/j.cmpb.2022.106896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 05/12/2022] [Accepted: 05/15/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND AND OBJECTIVE In the last few years, we have been exploring the use of transparent nanocrystalline yttria-stabilized zirconia (nc-YSZ) ceramics as a biomedical transparent cranial implant, referred as the "Window to the Brain" (WttB). The WttB aims at providing chronical optical access to the brain for diagnostics and therapeutic procedures and it has shown to provide an effective means to obtain enhanced results from optical imaging techniques. The objective of this work is to explore the photothermal effects of the Wttb produced when it is irradiated by a laser source. METHODS We make experimental and computer models. The thermal effects of laser irradiation on the nc-YSZ samples were evaluated upon registering the induced temperature changes by means of thermal imaging. The computer models try to mimic the experimental models using a similar geometry, reproducing the physical situation by a couple thermal-optical problem and adjusting the main parameters from the experimental results. RESULTS Experimental and computational coincides in results: Temperatures at the bottom surface of the implant does not exceed those which produce thermal damage. The quantitative comparison between experimental and computational models show that differences in results are under a reasonable value of 5% and qualitatively we observe a similar behavior. The results provide optimum values for the thermal-optical nc-YSZ parameters considering a linear and exponential relationship with temperature for the absorption coefficient: The thermal conductivity is k = 2.13 W/m·K and the absorption coefficient α varies from 426 to 526 m-1 with the linear relationship, and k = 2.04 W/m·K and α ∈ [433,502] m-1 with the exponential. The reflection coefficient is R = 19% in both cases. CONCLUSIONS The temperatures achieved in the nc-YSZ during the laser irradiation are suitable for biomedical applications. The combination of experimental and computational models contributes to build a clinically oriented model with the thermal-optical parameters values stablished and to determine their influence in results. Specifically, the absorption coefficient of the nc-YSZ samples is the most influent parameter in the obtained temperatures. Moreover, this combination provides a method to evaluate the relevant thermal-optical parameters of nc-YSZ samples obtained with different manufacturing processes.
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Affiliation(s)
- Mildred S Cano-Velázquez
- Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Ciudad de México, México
| | - Jose Bon
- Food Technology Department, Universitat Politècnica de València, Valencia, Spain
| | - M Llamazares
- Department of Applied Mathematics, BioMIT, Universitat Politècnica de València, Valencia, Spain
| | - Santiago Camacho-López
- Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Ensenada, B.C., México
| | - Guillermo Aguilar
- J. Mike Walker '66 Department of Mechanical Engineering, Texas A&M University, College Station, TX, USA
| | - Juan Hernández-Cordero
- Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Ciudad de México, México
| | - Macarena Trujillo
- Department of Applied Mathematics, BioMIT, Universitat Politècnica de València, Valencia, Spain.
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Halaney DL, Katta N, Fallah H, Aguilar G, Milner TE. Group Refractive Index of Nanocrystalline Yttria-Stabilized Zirconia Transparent Cranial Implants. Front Bioeng Biotechnol 2021; 9:619686. [PMID: 33869149 PMCID: PMC8044953 DOI: 10.3389/fbioe.2021.619686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 03/02/2021] [Indexed: 11/18/2022] Open
Abstract
Transparent “Window to the Brain” (WttB) cranial implants made from a biocompatible ceramic, nanocrystalline Yttria-Stabilized Zirconia (nc-YSZ), were recently reported. These reports demonstrated chronic brain imaging across the implants in mice using optical coherence tomography (OCT) and laser speckle imaging. However, optical properties of these transparent cranial implants are neither completely characterized nor completely understood. In this study, we measure optical properties of the implant using a swept source OCT system with a spectral range of 136 nm centered at 1,300 nm to characterize the group refractive index of the nc-YSZ window, over a narrow range of temperatures at which the implant may be used during imaging or therapy (20–43°C). Group refractive index was found to be 2.1–2.2 for OCT imaging over this temperature range. Chromatic dispersion for this spectral range was observed to vary over the sample, sometimes flipping signs between normal and anomalous dispersion. These properties of nc-YSZ should be considered when designing optical systems and procedures that propagate light through the window, and when interpreting OCT brain images acquired across the window.
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Affiliation(s)
- David L Halaney
- Laboratory of Guillermo Aguilar, Department of Mechanical Engineering, University of California, Riverside, Riverside, CA, United States
| | - Nitesh Katta
- Laboratory of Thomas Milner, Department of Biomedical Engineering, University of Texas, Austin, TX, United States
| | | | - Guillermo Aguilar
- Laboratory of Guillermo Aguilar, Department of Mechanical Engineering, University of California, Riverside, Riverside, CA, United States
| | - Thomas E Milner
- Laboratory of Thomas Milner, Department of Biomedical Engineering, University of Texas, Austin, TX, United States
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