Aislamiento confiable de microvasculares del sistema nervioso central en cinco grupos de vertebrados
Summary
El objetivo de este protocolo es aislar los microvasculares de múltiples regiones del sistema nervioso central de vertebrados lisencéfalos y gyrencéfalos.
Abstract
El aislamiento de los microvasculares del sistema nervioso central (SNC) se realiza comúnmente mediante la combinación de tejido cortical de múltiples animales, la mayoría de las veces roedores. Este enfoque limita el interrogatorio de las propiedades de la barrera hematoencefálica (BBB) a la corteza y no permite la comparación individual. Este proyecto se centra en el desarrollo de un método de aislamiento que permite la comparación de la unidad neurovascular (NVU) de múltiples regiones del SNC: corteza, cerebelo, lóbulo óptico, hipotálamo, hipófisis, tronco encefálico y médula espinal. Además, este protocolo, desarrollado originalmente para muestras murinas, fue adaptado con éxito para su uso en tejidos del SNC de especies de vertebrados pequeños y grandes de los que también somos capaces de aislar microvas de la materia blanca del hemisferio cerebral. Este método, cuando se combina con inmunoetiquetado, permite la cuantificación de la expresión de proteínas y la comparación estadística entre individuos, tipo de tejido o tratamiento. Demostramos esta aplicabilidad evaluando los cambios en la expresión de proteínas durante la encefalomielitis autoinmune experimental (EAE), un modelo murino de una enfermedad neuroinflamatoria, esclerosis múltiple. Además, los microbuques aislados por este método podrían utilizarse para aplicaciones posteriores como qPCR, RNA-seq y Western blot, entre otros. Aunque este no es el primer intento de aislar los microrridos del SNC sin el uso de ultracentrifugación o disociación enzimática, es único en su adecuación para la comparación de individuos individuales y múltiples regiones del SNC. Por lo tanto, permite la investigación de una gama de diferencias que de otro modo pueden permanecer oscuras: porciones del SNC (córtex, cerebelo, lóbulo óptico, tronco encefálico, hipotálamo, hipófisis y médula espinal), tipo de tejido del SNC (materia gris o blanca), individuos, grupos de tratamiento experimental, y las especies.
Introduction
Nuestro cerebro es el órgano más importante de nuestro cuerpo. Por esta razón, mantener la homeostasis cerebral a pesar de factores externos que pueden desencadenar una desviación de la normalidad es una prioridad. Según algunos eruditos, hace unos 400-500 millones de años1, los animales vertebrados desarrollaron lo que ahora conocemos como la barrera hematoencefálica (BBB)2,3. Esta “cerca” protectora ejerce la mayor influencia sobre la homeostasis del sistema nervioso central (SNC) y funciona regulando estrechamente el transporte de iones, moléculas y células entre la sangre y el parénquima del SNC. Cuando el BBB se interrumpe, el cerebro se vuelve susceptible a la exposición tóxica, infección, y la inflamación. Por lo tanto, la disfunción BBB se asocia con muchos, si no todos, trastornos neurológicos y neurodesarrollo4,5,6.
La sofisticada función del BBB se atribuye a la microvasculatura única del SNC conformada por la unidad neurovascular (NVU)2,3. Células endoteliales altamente especializadas, pericitas y pies de punta astrocíticos son los componentes celulares de la NVU2,3. La matriz extracelular generada por estas células también es esencial para la fisiología NVU y BBB2,3. Aunque los componentes celulares y moleculares esenciales de la NVU se conservan entre los vertebrados, la heterogeneidad se reporta entre las órdenes y las especies7,8. Sin embargo, las limitaciones técnicas impiden nuestra capacidad de considerar plenamente estas diferencias en la neurobiología, la investigación biomédica o traslacional.
Debido a esto, ampliamos un método de aislamiento de microbuques específico de la región del SNC para hacerlo aplicable a numerosas especies de los cinco grupos de vertebrados: peces, anfibios, reptiles, aves y mamíferos. El protocolo se describe para su uso en vertebrados lisencéfalos y grandes, incluidas las especies con relevancia traslacional9. Además, incluimos otras regiones del SNC no investigadas antes en este contexto, pero relevantes para la neurofisiología y con tremendas implicaciones clínicas: el hipotálamo, la hipófisis y la materia blanca. Por último, probamos la capacidad de este método de aislamiento como una herramienta fiable para identificar cambios en la expresión proteica a lo largo de la NVU y/o BBB9,10,11. Como prueba de concepto, mostramos cómo determinar los cambios en la expresión VCAM-1 y JAM-B durante EAE utilizando el método de aislamiento seguido de inmunofluorescencia.
Protocol
Representative Results
Discussion
El BBB incluye las propiedades únicas de las células endoteliales de microvasculatura cerebral del cerebro acopladas por una sofisticada arquitectura de uniones estrechas, adheridas, “peg-socket”, y placas de adhesión críticas para la homeostasisdelSNC2,3,19. Las propiedades de las células endoteliales son inducidas y mantenidas por pericitos y los procesos de pie final de la astroglia circundante2<s…
Disclosures
The authors have nothing to disclose.
Acknowledgements
El Dr. Cruz-Orengo contó con el apoyo de la Universidad de California, Davis, School of Veterinary Medicine Start Up Funds.
Materials
| 10X PBS | ThermoFisher | BP39920 | Used for blocking and antibody diluent. |
| 20% PFA | Electron Microscopy Sciences | 15713-S | Used as fixative (4% PFA) |
| 70,000 MW Dextran | Millipore Sigma | 9004-54-0 | Used for MV-2 solution |
| Adson Forceps | Fine Science Tools (FST) | 11006-12 | Used for removal of muscle and skin |
| Adson Forceps, student quality | FST | 91106-12 | Same as above but cheaper |
| Bovine serum albumin (BSA) | Millipore Sigma | A7906-100G | Used for MV-3 solution, blocking and antibody diluent |
| Corning 100 μm Cell strainer | Millipore Sigma | CLS431752-50EA | |
| Corning 70 μm Cell strainer | Millipore Sigma | CLS431751-50EA | |
| Corning Deskwork low-binding tips | Millipore Sigma | CLS4151 | Same as below but cheaper. |
| Cultrex Poly-D-Lysine | R&D | 3439-100-01 | Used for slide coating |
| Donkey anti-Goat IgG-ALEXA 555 | Thermo | A21432 | Used as secondary antibody. Recommended dilution of 1:200. |
| Donkey anti-Mouse IgG-ALEXA 488 | Thermo | A21202 | Used as secondary antibody. Recommended dilution of 1:200. |
| Donkey anti-Rabbit IgG-ALEXA 488 | Thermo | A21206 | Used as secondary antibody. Recommended dilution of 1:200. |
| Donkey anti-Rabbit IgG-ALEXA 647 | Thermo | A31573 | Used as secondary antibody. Recommended dilution of 1:200. |
| Donkey anti-Rat IgG-DyLight 650 | Thermo | SA5-10029 | Used as secondary antibody. Recommended dilution of 1:200. |
| Double-Pronged Tissue Pick | FST | 18067-11 | Used for removal of meninges and choroid plexus |
| Dumont #3c Forceps | FST | 11231-20 | Used for more delicate and/or small CNS tissue handling (like pituitary) |
| Dumont #7 Forceps | FST | 11274-20 | Used for CNS tisssue dissection and handling |
| Dumont #7 Forceps, student | FST | 91197-00 | Same as above but cheaper |
| ep Dualfilter T.I.P.S. LoRetention Tips | Eppendorf | 22493008 | Better quality than the tips above (more expensive). |
| Extra Fine Graefe Forceps, serrated | FST | 11151-10 | Used for bone removal |
| Fine Scissors, sharp | FST | 14060-09 | Used for removal of pig and macaque dural sac |
| Glass Pestle 1.5 mL Microcentrifuge Tube Tissue Grinder Homogenizer, Pack of 10 | Chang Bioscience Inc. (eBay) | GP1.5_10 | Used for small vetebrate hypothalus and pituitary. |
| Goat anti-CXCL12, biotinylated | PeproTech | 500-P87BGBT | Used as primary antibody on CNS microvessels from all specimens. Recommended dilution: 1:20. |
| Goat anti-JAM-B | R&D | AF1074 | Used as primary antibody to assess neuroinflammation. Recommended concentration: 5 μg/mL. |
| Goat anti-Mouse IgG-ALEXA 488 | Thermo | A11001 | Used as secondary antibody. Recommended dilution of 1:200. |
| Goat anti-Mouse IgG-ALEXA 555 | Thermo | A21424 | Used as secondary antibody. Recommended dilution of 1:200. |
| Goat anti-PDGFRβ | R&D | AF1042 | Used as primary antibody on CNS microvessels from all specimens. Recommended concentration: 5 μg/mL. |
| Goat anti-Rabbit IgG-ALEXA 555 | Thermo | A21249 | Used as secondary antibody. Recommended dilution of 1:200. |
| Goat anti-Rabbit IgG-DyLight 488 | Thermo | 35552 | Used as secondary antibody. Recommended dilution of 1:200. |
| Goat anti-Rat IgG-DyLight 650 | Thermo | SA5-10021 | Used as secondary antibody. Recommended dilution of 1:200. |
| Graefe Forceps, curved tip, 1X2 teeth | FST | 11054-10 | Use for nylon filter net holding and shaking |
| HBSS, 1X buffer with calcium and magnesium | Corning | 21-022-CM | Used for MV-1 solution |
| HEPES, 1M liquid buffer | Corning | 25-060-CI | Used for MV-1 solution |
| Isolectin GS-IB4-Biotin-XX | ThermoFisher Scientific (Thermo) | I21414 | Glycoprotein isolated from legume Griffonia simplicifolia that binds D-galactosyl residues of endothelial cell glycocalysx. Used for avian and porcine CNS microvessels. Recommended concentration: 5 μg/mL. |
| LaGrange Scissors, serrated | FST | 14173-12 | Used for skull dissection and laminectomy (except pig and macaque) |
| Millicell EZ slide 8-well unit | Millipore Sigma | PEZGS0816 | |
| Mouse anti-CLDN5 | Thermo | 35-2500 | Used as primary antibody on CNS microvessels from all specimens. Recommended concentration: 5 μg/mL. |
| Mouse anti-GGT1 | Abcam | ab55138 | Used as primary antibody on CNS microvessels from all specimens. Recommended concentration: 5 μg/mL. |
| Mouse anti-Human CD31 | R&D | BBA7 | Used as primary antibody on primate CNS microvessels. Recommended concentration: 16.5 μg/mL. |
| Mouse anti-NFM | Thermo | RMO-270 | Used as primary antibody on CNS microvessels from all specimens. Recommended concentration: 5 μg/mL. |
| Mouse anti-αSMA | Thermo | MA5-11547 | Used as primary antibody on CNS microvessels from all specimens. Recommended dilution of 1:200. |
| Nylon Filter Net, roll | Millipore Sigma | NY6000010 | Laser-cut to 13 mm diameter filter net discs. Used for small vetebrate hypothalus and pituitary. |
| Nylon Filter Nets, 25 mm | Millipore Sigma | NY2002500 | Used on most small vertebrates CNS tissues, except hypothalamus and pituitary. Used for macaque and pig hypothalamus and pituitary. |
| Nylon Filter Nets, 47 mm | Millipore Sigma | NY2004700 | Used for macaque and pig CNS tissues, except hypothalamus and pituitary. |
| ProLong Gold antifade reagent with DAPI | ThermoFisher | P36935 | Used to coverslip slides. |
| Rabbit anti-AQP4 | Millipore Sigma | A5971 | Used as primary antibody on CNS microvessels from all specimens. Recommended dilution of 1:200. |
| Rabbit anti-LSR | Millipore Sigma | SAB2107967 | Used as primary antibody on CNS microvessels from all specimens. Recommended concentration: 5 μg/mL. |
| Rabbit anti-NG2 | Millipore Sigma | AB5320 | Used as primary antibody on CNS microvessels from all specimens. Recommended dilution of 1:200. |
| Rabbit anti-OSP | Abcam | ab53041 | Used as primary antibody on CNS microvessels from all specimens. Recommended concentration: 1 μg/mL. |
| Rabbit anti-VE-Cadherin | Abcam | ab33168 | Used as primary antibody on CNS microvessels from all specimens. Recommended concentration: 5 μg/mL. |
| Rabbit anti-ZO-1 | Thermo | 61-7300 | Used as primary antibody on CNS microvessels from all specimens. Recommended concentration: 5 μg/mL. |
| Rat anti-CD31 | Becton Dickinson | BD 550274 | Used as primary antibody for murine CNS microvessels. Recommended concentration: 5 μg/mL. |
| Rat anti-GFAP | Thermo | 13-0300 | Used as primary antibody on CNS microvessels from all specimens. Recommended dilution of 1:200. |
| Rat anti-VCAM-1 | Becton Dickinson | BD 553329 | Used as primary antibody to assess neuroinflammation. Recommended concentration: 5 μg/mL. |
| Sterile Ringer's Solution, Frog | Aldon Corporation | IS5066 | Used for amfibian anesthesia |
| Streptavidin-ALEXA 555 | Thermo | S32355 | Used as secondary antibody to label biotinylated primary antibodies. Recommended dilution of 1:500. |
| Streptavidin-ALEXA 647 | Thermo | S32357 | Used as secondary antibody to label biotinylated primary antibodies. Recommended dilution of 1:500. |
| Surgical Scissors, sharp | FST | 14002-12 | Used for removal of muscle and skin |
| Surgical Scissors, sharp-blunt | FST | 14001-16 | Used for decapitation (except pig and macaque) |
| Swinnex Filter Holder, 13 mm | Millipore Sigma | SX0001300 | Modified by laser-cut. Used for small vetebrate hypothalus and pituitary. |
| Swinnex Filter Holder, 25 mm | Millipore Sigma | SX0002500 | Modified by laser-cut. Used on most small vertebrates CNS tissues, except hypothalamus and pituitary. Used for macaque and pig hypothalamus and pituitary. |
| Swinnex Filter Holder, 47 mm | Millipore Sigma | SX0004700 | Modified by laser-cut. Used for macaque and pig CNS tissues, except hypothalamus and pituitary. |
| Triton X-100 | ThermoFisher | 50-165-7277 | Used for blocking and antibody diluent. |
| Wheaton 120 Vac Overhead Stirrer | VWR (Supplier DWK Life Sciences) | 62400-904 (DWK #903475) | Used for macaque and pig CNS tissues with 55 mL tissue grinder, except hypothalamus and pituitary. |
| Wheaton Potter-Elvehjem tissue grinder with PTFE pestle, 10 mL | VWR (Supplier DWK Life Sciences) | 14231-384 (DWK #357979) | Used on most small vertebrates CNS tissues, except hypothalamus and pituitary. Used for macaque and pig hypothalamus and pituitary. |
| Wheaton Potter-Elvehjem tissue grinder with PTFE pestle, 55 mL | VWR (Supplier DWK Life Sciences) | 14231-372 (DWK #357994) | Used for macaque and pig CNS tissues, except hypothalamus and pituitary. |
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