title: Multiphoton microscopy guides neurotrophin modification with poly(ethylene glycol) to enhance interstitial diffusion.
abstract: Brain-derived neurotrophic factor (BDNF) is a promising therapeutic agent for the treatment of neurodegenerative diseases. However, the limited distribution of this molecule after administration into the brain tissue considerably hampers its efficacy. Here, we show how multiphoton microscopy of fluorescently tagged BDNF in brain-tissue slices provides a useful and rapid screening method for examining the diffusion of large molecules in tissues, and for studying the effects of chemical modifications-for example, conjugating with polyethylene glycol (PEG)-on the diffusion constant. This single variable, obtained by monitoring short-term diffusion in real time, can be effectively used for rational drug design. In this study on fluorescently tagged BDNF and BDNF-PEG, we identify slow diffusion as a major contributing factor to the limited penetration of BDNF, and demonstrate how chemical modification can be used to overcome this barrier.
authors.affiliation: Department of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Stroh
authors.forename: Warren R
authors.initials: WR
authors.lastname: Zipfel
authors.forename: Rebecca M
authors.initials: RM
authors.lastname: Williams
authors.forename: Shu Chin
authors.initials: SC
authors.lastname: Ma
authors.forename: Watt W
authors.initials: WW
authors.lastname: Webb
authors.forename: W Mark
authors.initials: WM
authors.lastname: Saltzman
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D019208:Brain-Derived Neurotrophic Factor / Q000737:chemistry / Q000493:pharmacokinetics*; D003198:Computer Simulation; D004058:Diffusion; D005110:Extracellular Space / Q000378:metabolism*; D036641:Microscopy, Fluorescence, Multiphoton / Q000379:methods*; D016011:Normal Distribution; D011092:Polyethylene Glycols / Q000737:chemistry*; D051381:Rats; D012235:Rhodamines / Q000737:chemistry; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D012235:Rhodamines; D011092:Polyethylene Glycols