Name: rewiring neuronal circuits: a new method for fast neurite extension and functional neuronal connection
Uploaded: 2017-06-13T14:00:00
Description: Watch this Scientific Journal Video about Rewiring Neuronal Circuits: A New Method for Fast Neurite Extension and Functional Neuronal Connection at JoVE.com

We would like to thank Yoichi Miyahara for many helpful discussions and insights. MA and PG acknowledge funding from NSERC.

All procedures detailed below were approved by McGill University&#39;s Animal Care Committee and conformed to the guidelines of the Canadian Council of Animal Care.
1. Standardization of Neuronal Cultures Using Microfluidic Devices: Device Assembly
<ol>
	<li>Select a suitable microfluidic device for the desired experiment. To connect neurons within the same population, use the Neuro Devices (Figure 1) and to connect neurons in different populations use the Co-Cu...

<ol>
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Using standard micromanipulation and innovative microfluidic devices, a new technique was developed to rapidly initiate, elongate and precisely connect new functional neuronal circuits over large distances. Pipette micromanipulation is a common tool in most neuroscience labs4,13. The real challenge to achieving reproducible and reliable results was standardization of healthy, precisely positioned neuronal cultures for the duration of the experiment (which can be ...

Injuries to the adult central nervous system (CNS) may lead to permanent disability due to multiple mechanisms that limit axonal regrowth1. Following injury, many CNS axons do not form a new growth cone and fail to mount an effective regenerative response2. Furthermore, damage and scar tissue surrounding CNS lesions significantly inhibit axonal growth1,2,3. Current therapies to promote CNS regeneration after injury have focused on enhancing the intrinsic growth potential of the injured neuron and on masking the inhibitors of axonal extension associated with myelin debris and the glial scar1,3. Despite this, the capacity to regenerate long axons to distant targets and to form appropriate functional synapses remains severely limited4,5,6,7.
In the present work, microbeads, pipette micromanipulation, and microfluidic devices are used to rapidly initiate, elongate, and precisely connect new functional neuronal circuits over long distances. Previous work has shown that poly-D-lysine-coated beads (PDL-beads) induce membrane adhesion followed by the clustering of synaptic vesicle complexes and the formation of functional presynaptic boutons8. It was also shown that when the PDL-bead is mechanically pulled away after presynaptic differentiation, the synaptic protein cluster follows the bead, initiating a new neurite9. The following procedure exploits this fact along with the ability to culture embryonic hippocampal neurons of rats into organized regions on a coverslip using polydimethylsiloxane (PDMS) microfluidic devices to precisely rewire a neuronal circuit.
These PDMS microfluidic devices are non-toxic, optically transparent and consist of two chambers connected by a system of microchannels. Once assembled on a coverslip, each device serves as a mold to guide neuronal growth and maintain healthy neuronal cultures on precise patterns for longer than 4 weeks in vitro.
Here, a framework is presented in which to investigate the limits of extension and functionality of the new neurite. New, functional neurites are created and positioned to controllably (re)wire neuronal networks. The extension rates achieved are faster than 20 &#181;m/min over millimeter-scale distances and functional connections are established. These results show, unexpectedly, that the intrinsic capacity of these neurites for elongation is much faster than previously thought. This proposed mechanical approach bypasses slow chemical strategies and enables controlled connection to a specific target. This technique opens new avenues for the in vitro study of novel therapies to restore neuronal connectivity after injury. It also enables the manipulation and rewiring of neuronal networks to investigate fundamental aspects of neuronal signal processing and neuronal function in vitro.

<table border="0" cellpadding="0" cellspacing="0" width="836">
	<tbody>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">Co-culture devices</td>
			<td style="width:104px;">Ananda Devices</td>
			<td style="width:119px;"></td>
			<td style="width:397px;">Commercially available at http://www.anandadevices.com</td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">Neuro devices</td>
			<td style="width:104px;">Ananda Devices</td>
			<td style="width:119px;"></td>
			<td>Commercially available at http://www.anandadevices.com</td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">No. 1 Glass Coverslip 25 mm Round</td>
			<td style="width:104px;">Warner Instruments</td>
			<td style="width:119px;">64-0705</td>
			<td></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">35mm Glass Bottom Dishes #0, Uncoated, Gamma-Irradiated</td>
			<td style="width:104px;">MatTex Incorporation</td>
			<td style="width:119px;">P35G-0-20-C</td>
			<td></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">35mm cell culture dish, Non-Pyrogenic, Sterile</td>
			<td style="width:104px;">Corning Inc</td>
			<td style="width:119px;">430165</td>
			<td></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">95mmx15mm Petri Dish, Slippable Lid, Sterile Polystyrene</td>
			<td style="width:104px;">Fisherbrand</td>
			<td>FB0875714G</td>
			<td></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">50mL Centrifuge tubes with printed graduations and flat caps</td>
			<td style="width:104px;">VWR</td>
			<td style="width:119px;">89039-656</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">15mL Polypropylene Conical Tube, 17x120mm style, Non Pyrogenic, Sterile</td>
			<td>Falcon</td>
			<td>352097</td>
			<td></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">Neurobasal Medium</td>
			<td style="width:104px;">Life Technologies</td>
			<td style="width:119px;">21103-049</td>
			<td>Extracellular solution</td>
		</tr>
		<tr height="81">
			<td height="81" style="height:81px;width:216px;">B-27 Supplement (50X), serum free</td>
			<td style="width:104px;">B-27 Supplement (50X), serum free</td>
			<td style="width:119px;">17504044</td>
			<td>Extracellular solution</td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">Pennicilin, Streptomyocin, Glutamine</td>
			<td style="width:104px;">Thermo Fisher Scientific&#160;</td>
			<td>11995-065</td>
			<td>Extracellular solution</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:216px;">200uL Pipettors</td>
			<td style="width:104px;">VWR</td>
			<td>89079-458</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:216px;">2-20uL Pipettors</td>
			<td style="width:104px;">Aerosol Resistant Tips</td>
			<td style="width:119px;">2149P</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">BD Falcon 3mL Transfer Pipettes [Non-sterile]</td>
			<td>BD Falcon</td>
			<td>357524</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Glucose</td>
			<td style="width:104px;">Gibco</td>
			<td style="width:119px;">15023-021</td>
			<td>Extracellular solution</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">HEPES</td>
			<td style="width:104px;">Sigma</td>
			<td style="width:119px;">7365-45-9</td>
			<td>Extracellular solution/Beads</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">NaCl</td>
			<td style="width:104px;">Sigma-Aldrich</td>
			<td style="width:119px;">7647-14-5</td>
			<td>Extracellular solution</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">KCl</td>
			<td style="width:104px;">Sigma-Aldrich</td>
			<td style="width:119px;">7447-40-7</td>
			<td>Extracellular solution</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">CaCl2</td>
			<td style="width:104px;">Sigma-Aldrich</td>
			<td style="width:119px;">10043-52-4</td>
			<td>Extracellular solution</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">MgCl2</td>
			<td style="width:104px;">Sigma-Aldrich</td>
			<td style="width:119px;">7786-30-3</td>
			<td>Extracellular solution</td>
		</tr>
		<tr height="61">
			<td height="61" style="height:61px;width:216px;">#5 Dumont Dumostar Tweezers 11cm</td>
			<td style="width:104px;">World Precision Instruments</td>
			<td>500233</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Dissection tools</td>
			<td>Braun, Aesculap</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Poly-D-lysine Hydrobromide</td>
			<td>Sigma-Aldrich</td>
			<td>P6407</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:216px;">Micro particles based on polystyrene, 10 um</td>
			<td style="width:104px;">Sigma-Aldrich</td>
			<td style="width:119px;">72986</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:216px;">Borosilicate tubes</td>
			<td style="width:104px;">King Precision Glass, Inc.</td>
			<td style="width:119px;">14696-2</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:216px;">Horizontal Pipette Puller</td>
			<td style="width:104px;">Sutter Instruments</td>
			<td style="width:119px;">Brown-Flaming P-97</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:216px;">Micromanipulators, PCS-5000 Series</td>
			<td style="width:104px;">SD Instruments</td>
			<td style="width:119px;">MC7600R</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">1 ml Syringe</td>
			<td style="width:104px;">BD Luer-Lok</td>
			<td>309628</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Inverted Microscope</td>
			<td style="width:104px;">Olympus&#160;</td>
			<td style="width:119px;">IX71</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:216px;">Objective</td>
			<td style="width:104px;">Olympus</td>
			<td style="width:119px;">UIS2, LUCPLFLN 40X</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">CCD Camera</td>
			<td style="width:104px;">Photometrics</td>
			<td style="width:119px;">Cascade II: 512</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Leibovitz&#39;s (1x) L-15 Medium</td>
			<td>Life Technologies</td>
			<td>11415-064</td>
			<td>Rat Dissection</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Typsin-EDTA (0.05%), Phenol red</td>
			<td>Life Technologies</td>
			<td>25300054</td>
			<td>Rat Dissection</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">DMEM (1x) Dulbecco&#39;s Modified Eagle Medium [+4.5 g/L D-Glucose, + L-Glutamine, + 110 mg/L Sodium Pyruvate]</td>
			<td>Life Technologies</td>
			<td>11995-065</td>
			<td>Rat Dissection</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">HBSS (1x) Hank&#39;s Balanced Salt Solution [- Calcium Chloride, - Magnesium Chloride, - Magnesium Sulfate]</td>
			<td>Life Technologies</td>
			<td>14170-112</td>
			<td>Rat Dissection</td>
		</tr>
	</tbody>
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rewiring neuronal circuits: a new method for fast neurite extension and functional neuronal connection

Brain and spinal cord injury may lead to permanent disability and death because it is still not possible to regenerate neurons over long distances and accurately reconnect them with an appropriate target. Here a procedure is described to rapidly initiate, elongate, and precisely connect new functional neuronal circuits over long distances. The extension rates achieved reach over 1.2 mm/h, 30-60 times faster than the in vivo rates of the fastest growing axons from the peripheral nervous system (0.02 to 0.04 mm/h)28 and 10 times faster than previously reported for the same neuronal type at an earlier stage of development4. First, isolated populations of rat hippocampal neurons are grown for 2-3 weeks in microfluidic devices to precisely position the cells, enabling easy micromanipulation and experimental reproducibility. Next, beads coated with poly-D-lysine (PDL) are placed on neurites to form adhesive contacts and pipette micromanipulation is used to move the resulting bead-neurite complex. As the bead is moved, it pulls out a new neurite that can be extended over hundreds of micrometers and functionally connected to a target cell in less than 1 h. This process enables experimental reproducibility and ease of manipulation while bypassing slower chemical strategies to induce neurite growth. Preliminary measurements presented here demonstrate a neuronal growth rate far exceeding physiological ones. Combining these innovations allows for the precise establishment of neuronal networks in culture with an unprecedented degree of control. It is a novel method that opens the door to a plethora of information and insights into signal transmission and communication within the neuronal network as well as being a playground in which to explore the limits of neuronal growth. The potential applications and experiments are widespread with direct implications for therapies that aim to reconnect neuronal circuits after trauma or in neurodegenerative diseases.

Embryonic rat hippocampal neurons are cultured in microfluidic devices to enable precise positioning of cells, PDL-beads and micromanipulators. The first step is to properly assemble the microfluidic device on a glass coverslip or dish. It is essential that the microfluidic device be well attached to the substrate to avoid cells exiting the chambers and moving under the parts of the device that should be sealed (Figure 1a). To maintain healthy cultures for se...

Watch this Scientific Journal Video about Rewiring Neuronal Circuits: A New Method for Fast Neurite Extension and Functional Neuronal Connection at JoVE.com

Rewiring Neuronal Circuits: A New Method for Fast Neurite Extension and Functional Neuronal Connection

This procedure describes how to rapidly initiate, extend and connect neurites organized in microfluidic chambers using poly-D-lysine-coated beads fixed to micropipettes that guide neurite elongation.

Brain and spinal cord injury may lead to permanent disability and death because it is still not possible to regenerate neurons over long distances and ...

Research

JoVE Journal

Neuroscience

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