Optical properties of mouse brain tissue after optical clearing with FocusClear™

Abstract. Fluorescence microscopy is commonly used to investigate disease progression in biological tissues. Biological tissues, however, are strongly scattering in the visible wavelengths, limiting the application of fluorescence microscopy to superficial (<200  μm) regions. Optical clearing, which involves incubation of the tissue in a chemical bath, reduces the optical scattering in tissue, resulting in increased tissue transparency and optical imaging depth. The goal of this study was to determine the time- and wavelength-resolved dynamics of the optical scattering properties of rodent brain after optical clearing with FocusClear™. Light transmittance and reflectance of 1-mm mouse brain sections were measured using an integrating sphere before and after optical clearing and the inverse adding doubling algorithm used to determine tissue optical scattering. The degree of optical clearing was quantified by calculating the optical clearing potential (OCP), and the effects of differing OCP were demonstrated using the optical histology method, which combines tissue optical clearing with optical imaging to visualize the microvasculature. We observed increased tissue transparency with longer optical clearing time and an analogous increase in OCP. Furthermore, OCP did not vary substantially between 400 and 1000 nm for increasing optical clearing durations, suggesting that optical histology can improve ex vivo visualization of several fluorescent probes.

[1]  Bernard Choi,et al.  Reversible dissociation of collagen in tissues. , 2003, The Journal of investigative dermatology.

[2]  Bernard Choi,et al.  Optical Histology: A Method to Visualize Microvasculature in Thick Tissue Sections of Mouse Brain , 2013, PloS one.

[3]  Bernard Choi,et al.  Revisiting optical clearing with dimethyl sulfoxide (DMSO) , 2009, Lasers in surgery and medicine.

[4]  Christopher G. Rylander,et al.  Dehydration mechanism of optical clearing in tissue. , 2006, Journal of biomedical optics.

[5]  Bernard Choi,et al.  Determination of chemical agent optical clearing potential using in vitro human skin , 2005, Lasers in surgery and medicine.

[6]  H. G. Rylander,et al.  Use of an agent to reduce scattering in skin , 1999, Lasers in surgery and medicine.

[7]  Atsushi Miyawaki,et al.  Scale: a chemical approach for fluorescence imaging and reconstruction of transparent mouse brain , 2011, Nature Neuroscience.

[8]  W. Star,et al.  The relationship between integrating sphere and diffusion theory calculations of fluence rate at the wall of a spherical cavity. , 1995, Physics in medicine and biology.

[9]  A. Welch,et al.  A review of the optical properties of biological tissues , 1990 .

[10]  Frank Bradke,et al.  Three-dimensional imaging of the unsectioned adult spinal cord to assess axon regeneration and glial responses after injury , 2011, Nature Medicine.

[11]  A J Welch,et al.  Use of osmotically active agents to alter optical properties of tissue: Effects on the detected fluorescence signal measured through skin , 2001, Lasers in surgery and medicine.

[12]  Katsunori Ishii,et al.  Determination of the tumor tissue optical properties during and after photodynamic therapy using inverse Monte Carlo method and double integrating sphere between 350 and 1000 nm. , 2011, Journal of biomedical optics.

[13]  Bernard Choi,et al.  High-resolution visualization of mouse cardiac microvasculature using optical histology. , 2013, Biomedical optics express.

[14]  M. Levene,et al.  Multiphoton microscopy of cleared mouse organs. , 2010, Journal of biomedical optics.

[15]  Huikai Xie,et al.  Refractive index measurement of acute rat brain tissue slices using optical coherence tomography , 2012, Optics express.

[16]  Aleksey V Yuzhakov,et al.  Optical characteristics of the cornea and sclera and their alterations under the effect of nondestructive 1.56-μm laser radiation , 2013, Journal of biomedical optics.

[17]  Valery V. Tuchin,et al.  Optical clearing of tissues and blood using the immersion method , 2005 .

[18]  J. Pickering,et al.  Double-integrating-sphere system for measuring the optical properties of tissue. , 1993, Applied optics.

[19]  Aaron S. Andalman,et al.  Structural and molecular interrogation of intact biological systems , 2013, Nature.

[20]  B. Wilson,et al.  Measurement of Ex Vivo and In Vivo Tissue Optical Properties: Methods and Theories , 2010 .

[21]  S. Jacques Optical properties of biological tissues: a review , 2013, Physics in medicine and biology.

[22]  Frank Bradke,et al.  Three-dimensional imaging of solvent-cleared organs using 3DISCO , 2012, Nature Protocols.

[23]  M. Kohl,et al.  Near-infrared optical properties of ex vivo human skin and subcutaneous tissues measured using the Monte Carlo inversion technique. , 1998, Physics in medicine and biology.

[24]  Xiangqun Xu,et al.  Synergistic effect of hyperosmotic agents of dimethyl sulfoxide and glycerol on optical clearing of gastric tissue studied with near infrared spectroscopy. , 2004, Physics in medicine and biology.

[25]  A. Welch,et al.  Determining the optical properties of turbid mediaby using the adding-doubling method. , 1993, Applied optics.

[26]  Shiue-Cheng Tang,et al.  Optical clearing facilitates integrated 3D visualization of mouse ileal microstructure and vascular network with high definition. , 2010, Microvascular research.