Name: assessment of endothelial cell migration after exposure to toxic chemicals
Uploaded: 2015-07-10T13:00:00
Description: Watch this Scientific Journal Video about Assessment of Endothelial Cell Migration After Exposure to Toxic Chemicals at JoVE.com

This work was funded by the German Ministry of Defense (Grant No. M-SAB1-6-A009).

The following protocol describes techniques for the investigation of early endothelial cell migration. The proper cultivation of vascular endothelial cells requires pre-coating of cell culture flasks with gelatin to ensure proper proliferation and maintenance of an endothelial phenotype.
1. Pre-coating of Cell Culture Flasks
<ol>
	<li>Dissolve gelatin in 0.1 M PBS to a final concentration of 0.1%.</li>
	<li>Autoclave the solution with parameters for liquid autoclaving (for details see instru...

<ol>
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Dermal exposure to toxic chemicals often results in severe wound healing disorder. The underlying mechanisms are largely unknown. Wound healing is a complex process that consists of different phases (hemostasis, inflammation, proliferation and remodeling). Cell migration is involved in every phase, however, it is of utmost importance for the formation of the granulation tissue. Here, new blood vessels are formed either by angio- or vasculogenesis.
Both processes require unaffected migration of...

Cell migration is important in many physiological and pathophysiological processes including development, various diseases, and wound healing after skin injury.
Following skin injury, inflammation removes damaged or necrotic tissue and granulation drives preliminary wound closure and allows formation of a network of new capillaries through vasculogenesis (novel formation) or angiogenesis (sprouting of existing vesicles)1-3. Both vasculo- and angiogenesis require migration of endothelial cells. The growing network of blood vessels is essential to transport oxygen and nutrients to proliferating keratinocytes which ultimately undergo keratinization, form a new epithelium and provide wound closure.
Impaired migration of endothelial cells is an underlying cause of wound healing disorder4,5. Thus, methods to assess migration of early endothelial cells are required to explore the pathophysiology of cell migration disorders and to identify novel strategies for therapeutic intervention.
Dermal exposure to alkylating agents (e.g., sulfur and nitrogen mustards) causes wound healing disorder6. Such compounds were used as chemical warfare agents in several conflicts in the 20th century and remain reason for strong concern due to existing stockpiles in politically unstable regions and the relatively simple synthesis. Although sulfur mustard was first synthesized in 1822, the molecular and clinical pathology of SM exposure is not understood in detail and no antidote for SM exposure has been identified.
Several studies have been conducted to understand and to model impaired wound healing after SM exposure and to test for potential candidate compounds capable of reserving that effect. Schmidt et al. (2009) tested the effect of chlorambucil, an alkylating compound with properties similar to SM in mouse embryoid body models and found a dramatic, sometimes more than 99% reduction in vessel formation7. This adverse effect was most pronounced at a stage of development which, under physiological conditions, is dominated by the proliferation and migration of vascular endothelial precursor cells. Thus, these cells were identified to be particularly sensitive to alkylating agents. Steinritz et al. (2010) tested scavengers of reactive oxygen species (ROS), in particular, N-acetylcysteine (NAC) and alpha linolenic acid (ALA) for their ability to reduce SM toxicity in mouse embryoid body models and in particular, to restore vessel formation8. Temporary protective effects were observed, indicating that excessive ROS formation was likely to contribute to the adverse effects of SM on wound healing. These effects were not permanent and the two candidate compounds may not be capable of restoring vessel formation and wound healing in the long term8. However, those experiments were conducted in a complex 3D model which did allow investigation of cell migration. Thus, we subsequently tested NAC and ALA for beneficial effects on cell migration of EEC that have a key role in the process of vessel formation9.
Moreover, there is evidence that cell polarity is required for cell migration. Mitochondrial dysfunction leading to ROS formation was shown to impair cell polarity and may thus adversely affect cell migration. Therefore, live cell imaging with regard to mitochondrial function was performed and the effects of ROS scavengers were examined. The following protocol describes general requirements for the cultivation of EEC, the Boyden chamber assay, the wound healing assay including cell tracking analysis and the use of TMRM for assessment of mitochondrial function in detail. Important aspects of experimental protocols for EEC cultivation and migration are highlighted.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>Boyden Chamber&#160;</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Corning FluoroBlok Tissue Culture (TC)-treated Inserts, 24 well - 3 &#181;m</td>
			<td>Corning Incorporated</td>
			<td>#351151</td>
			<td></td>
		</tr>
		<tr>
			<td>Corning FluoroBlok Tissue Culture (TC)-treated Inserts, 24 well - 8 &#181;m</td>
			<td>Life Sciences</td>
			<td>#351152</td>
			<td></td>
		</tr>
		<tr>
			<td>(for use with Falcon Insert 24 well Companion Plate (353504)</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Wound&#160; healing assay</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Glass bottom dishes</td>
			<td>Word Precision Instruments, Inc.</td>
			<td>#FD35-100</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Assessment of mitochondrial potential</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>TMRM (tetramethylrhodamine methyl ester)</td>
			<td>Life Technologies</td>
			<td>#T669</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Cell culture</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Accutase</td>
			<td>PAA, Pasching, Austria</td>
			<td># L11-007</td>
			<td></td>
		</tr>
		<tr>
			<td>&#945;-Linolenic acid</td>
			<td>Fluka (Sigma), Steinheim, Germany</td>
			<td>&#160;# L2376</td>
			<td></td>
		</tr>
		<tr>
			<td>Chlorambucil</td>
			<td>Fluka (Sigma), Steinheim, Germany</td>
			<td># 23125</td>
			<td></td>
		</tr>
		<tr>
			<td>Gelatin</td>
			<td>Sigma-Aldrich, Steinheim, Germany</td>
			<td># G2500-100G</td>
			<td></td>
		</tr>
	</tbody>
</table>

assessment of endothelial cell migration after exposure to toxic chemicals

Exposure to chemical substances (including alkylating chemical warfare agents like sulfur and nitrogen mustards) cause a plethora of clinical symptoms including wound healing disorder. The physiological process of wound healing is highly complex. The formation of granulation tissue is a key step in this process resulting in a preliminary wound closure and providing a network of new capillary blood vessels &#8211; either through vasculogenesis (novel formation) or angiogenesis (sprouting of existing vessels). Both vasculo- and angiogenesis require functional, directed migration of endothelial cells. Thus, investigation of early endothelial cell (EEC) migration is important to understand the pathophysiology of chemical induced wound healing disorders and to potentially identify novel strategies for therapeutic intervention.
We assessed impaired wound healing after alkylating agent exposure and tested potential candidate compounds for treatment. We used a set of techniques outlined in this protocol. A modified Boyden chamber to quantitatively investigate chemokinesis of EEC is described. Moreover, the use of the wound healing assay in combination with track analysis to qualitatively assess migration is illustrated. Finally, we demonstrate the use of the fluorescent dye TMRM for the investigation of mitochondrial membrane potential to identify underlying mechanisms of disturbed cell migration. The following protocol describes basic techniques that have been adapted for the investigation of EEC.

Dermal exposure to alkylating agents provokes erythema, blister formation and dermal ulceration that is associated with a wound healing disorder. Wound healing requires angio- and vasculogenesis which are based on migration of endothelial cells. Quantitative migration can be assessed by use of the Boyden chamber assay. As shown in Figure 1C exposure of EEC to the alkylating agent chlorambucil resulted in a significant decrease in cell migration9. Addition of the ROS-scavenger alpha linolenic a...

Watch this Scientific Journal Video about Assessment of Endothelial Cell Migration After Exposure to Toxic Chemicals at JoVE.com

Assessment of Endothelial Cell Migration After Exposure to Toxic Chemicals

Investigation of early endothelial cell (EEC) migration is important to understand the pathophysiology of certain illnesses and to potentially identify novel strategies for therapeutic intervention. The following protocol describes techniques to assess cell migration that have been adapted for the investigation of EEC.

Exposure to chemical substances (including alkylating chemical warfare agents like sulfur and nitrogen mustards) cause a plethora of clinical symptoms ...

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