This work was supported by a grant RF-2011-02352331 from Ministero Italiano della Salute (to Armando Gabrielli).

All animal care and experimental procedures were approved by the Italian Ministry of Health (authorization n. 456/2016-PR) and performed according to the Declaration of Helsinki conventions.
1. Mice
<ol>
	<li>After purchasing them, allow the mice to acclimate for at least 7 days before the injection. 
	NOTE: Mice were housed in the animal facility under pathogen-free conditions, were maintained under constant temperature and humidity on a 12 h light/dark cycle, and were given free acces...

<ol>
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A., Aidinis, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modeling+pulmonary+fibrosis+with+bleomycin.">Modeling pulmonary fibrosis with bleomycin.</a> Current Opinion in Pulmonary Medicine. 17 (5), 355-361 (2011).</li><li>Moeller, A., Ask, K., Warburton, D., Gauldie, J., Kolb, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+bleomycin+animal+model:+a+useful+tool+to+investigate+treatment+options+for+idiopathic+pulmonary+fibrosis?.">The bleomycin animal model: a useful tool to investigate treatment options for idiopathic pulmonary fibrosis?.</a> International Journal of Biochemistry and Cell Biology. 40 (3), 362-382 (2008).</li><li>Moore, B. 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(122), e55224 (2017).</li><li>Moroncini, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mesenchymal+stromal+cells+from+human+umbilical+cord+prevent+the+development+of+lung+fibrosis+in+immunocompetent+mice.">Mesenchymal stromal cells from human umbilical cord prevent the development of lung fibrosis in immunocompetent mice.</a> PLoS One. 13 (6), e0196048 (2018).</li><li>Shahzeidi, S., Jeffery, P. K., Laurent, G. J., McAnulty, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Increased+type+I+procollagen+mRNA+transcripts+in+the+lungs+of+mice+during+the+development+of+bleomycin-induced+fibrosis.">Increased type I procollagen mRNA transcripts in the lungs of mice during the development of bleomycin-induced fibrosis.</a> European Respiratory Journal. 7 (11), 1938-1943 (1994).</li><li>Lee, R. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intravenous+hMSCs+improve+myocardial+infarction+in+mice+because+cells+embolized+in+lung+are+activated+to+secrete+the+anti-inflammatory+protein+TSG-6.">Intravenous hMSCs improve myocardial infarction in mice because cells embolized in lung are activated to secrete the anti-inflammatory protein TSG-6.</a> Cell Stem Cell. 5 (1), 54-63 (2009).</li><li>Scotton, C. J., Chambers, R. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bleomycin+revisited:+towards+a+more+representative+model+of+IPF?.">Bleomycin revisited: towards a more representative model of IPF?.</a> American Journal of Physiology-Lung Cellular and Molecular Physiology. 299 (4), L439-L441 (2010).</li><li>Cai, Y., Kimura, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Noninvasive+intratracheal+intubation+to+study+the+pathology+and+physiology+of+mouse+lung.">Noninvasive intratracheal intubation to study the pathology and physiology of mouse lung.</a> Journal of Visualized Experiments. (81), e50601 (2013).</li><li>Thomas, J. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endotracheal+intubation+in+mice+via+direct+laryngoscopy+using+an+otoscope.">Endotracheal intubation in mice via direct laryngoscopy using an otoscope.</a> Journal of Visualized Experiments. (86), e50269 (2014).</li><li>Vandivort, T. C., An, D., Parks, W. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+Improved+Method+for+Rapid+Intubation+of+the+Trachea+in+Mice.">An Improved Method for Rapid Intubation of the Trachea in Mice.</a> Journal of Visualized Experiments. (108), e53771 (2016).</li><li>Dutta, S., Sengupta, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Men+and+mice:+Relating+their+ages.">Men and mice: Relating their ages.</a> Life Sciences. 152, 244-248 (2016).</li><li>Sueblinvong, V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Predisposition+for+disrepair+in+the+aged+lung.">Predisposition for disrepair in the aged lung.</a> American Journal of Medical Sciences. 344 (1), 41-51 (2012).</li><li>Moodley, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+umbilical+cord+mesenchymal+stem+cells+reduce+fibrosis+of+bleomycin-induced+lung+injury.">Human umbilical cord mesenchymal stem cells reduce fibrosis of bleomycin-induced lung injury.</a> American Journal of Pathology. 175 (1), 303-313 (2009).</li><li>How, C. 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The authors have nothing to disclose.

Endotracheal administration is the preferential route for delivering exogenous agents into the lungs. Since several years, the direct injection of bleomycin into the trachea has been widely used to induce pulmonary fibrosis13 and, recently, more advanced, noninvasive techniques have been developed to accomplish this14,15,16.
The method described here provides several meaningful...

Pulmonary fibrosis is a progressive pathological process characterized by the excessive deposition of extracellular matrix components, mainly type I collagen, in the lung interstitium, leading to impaired lung function. It is the hallmark of several human lung diseases with a different etiology and represents a poor clinical prognostic factor. Since current therapies are rather limited1, mouse models continue to be an essential tool both for the further investigation of the pathogenic mechanisms influencing the onset and the progression of the disease and for developing new antifibrotic strategies2,3.
To date, the administration of bleomycin has been the most commonly applied model of experimentally induced pulmonary fibrosis4. Beside multiple delivering methods (including intravenous, intraperitoneal, subcutaneous, and inhalational), intratracheal or endotracheal injections of bleomycin have emerged as the most frequently used routes4,5. The method that we describe herein has been developed to avoid the scalding effect of bleomycin on the tracheal mucosa. In fact, by exteriorizing the trachea and visualizing it through an operating microscope, it is possible to achieve the instillation of the entire volume of bleomycin solution directly into the lower airway without any spills in the upper airway. When the required surgical expertise and instrumentation are available, this method allows for the safe, robust, and reproducible induction of lung inflammation and fibrosis, as reported below.

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	<tbody>
		<tr height="26">
			<td height="26" style="height:27px;width:369px;">C57BL/6 mice</td>
			<td style="width:236px;">Charles River</td>
			<td style="width:239px;">Jax Mice Stock n. 000664</td>
			<td style="width:180px;"></td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;">2,2,2-Tribromoethanol (Avertin)&#160;</td>
			<td style="width:236px;">Sigma-Aldrich</td>
			<td style="width:239px;">T48402</td>
			<td></td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;width:369px;">Barraquer Micro Needle Holder</td>
			<td style="width:236px;">Lawton</td>
			<td style="width:239px;">62-3755</td>
			<td></td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;width:369px;">Bleomycin sulfate</td>
			<td style="width:236px;">Sigma-Aldrich</td>
			<td>B1141000</td>
			<td></td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;">B&#252;rker chamber</td>
			<td style="width:236px;">Brand&#160;</td>
			<td style="width:239px;">718905</td>
			<td></td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;">Culture Flasks&#160;</td>
			<td style="width:236px;">EuroClone</td>
			<td style="width:239px;">ET7076</td>
			<td></td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;width:369px;">Disposable razors</td>
			<td style="width:236px;">Unigloves</td>
			<td style="width:239px;">4080</td>
			<td></td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;width:369px;">Dissecting Forceps</td>
			<td style="width:236px;">Aesculap Surgical Instruments</td>
			<td style="width:239px;">BD311R</td>
			<td></td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;width:369px;">DPBS</td>
			<td style="width:236px;">Gibco</td>
			<td style="width:239px;">14190-144</td>
			<td></td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;width:369px;">Heating pad</td>
			<td style="width:236px;">2Biological Instruments</td>
			<td style="width:239px;">557023</td>
			<td></td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;width:369px;">Isoflurane Vet</td>
			<td style="width:236px;">Merial Italia</td>
			<td>N01AB06</td>
			<td></td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;width:369px;">Operating Microscope</td>
			<td style="width:236px;">Carl Zeiss</td>
			<td style="width:239px;">Model OPM 16</td>
			<td></td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;">TrypLE Select Enzyme</td>
			<td style="width:236px;">Gibco</td>
			<td style="width:239px;">12563-029</td>
			<td></td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;width:369px;">Vannas Micro Scissors</td>
			<td style="width:236px;">Aesculap Surgical Instruments</td>
			<td style="width:239px;">OC498R</td>
			<td></td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;width:369px;">Vicryl Plus 4/0 Absorbable Suture, FS-2 needle 19 mm</td>
			<td style="width:236px;">Ethicon</td>
			<td style="width:239px;">VCP392ZH</td>
			<td></td>
		</tr>
	</tbody>
</table>

induction of mouse lung injury by endotracheal injection of bleomycin

Pulmonary fibrosis is a hallmark of several human lung diseases with a different etiology. Since current therapies are rather limited, mouse models continue to be an essential tool for developing new antifibrotic strategies. Here we provide an effective method to investigate in vivo antifibrotic activity of human mesenchymal stromal cells obtained from whole umbilical cord (hUC-MSC) in attenuating bleomycin-induced lung injury. C57BL/6 mice receive a single endotracheal injection of bleomycin (1.5 U/kg body weight) followed by a double infusion of hUC-MSC (2.5 x 105) into the tail vein, 24 h and 7 days after the bleomycin administration. Upon sacrifice at days 8, 14, or 21, inflammatory and fibrotic changes, collagen content, and hUC-MSC presence in explanted lung tissue are analyzed. The injection of bleomycin into the mouse&#160;trachea allows the direct targeting of the lungs, leading to extensive pulmonary inflammation and fibrosis. The systemic administration of a double dose of hUC-MSC results in the early blunting of the bleomycin-induced lung injury. Intravenously infused hUC-MSC are transiently engrafted into the mouse lungs, where they exert their anti-inflammatory and antifibrotic activity. In conclusion, this protocol has been successfully applied for the preclinical testing of hUC-MSC in an experimental mouse model of human pulmonary fibrosis. However, this technique can be easily extended both to study the effect of different endotracheally administered substances on the pathophysiology of the lungs and to validate new anti-inflammatory and antifibrotic systemic therapies.

Lung injury was induced by a single endotracheal injection of 1.5 U/kg body weight of bleomycin sulfate in 100 &#181;L of sterile saline. Control animals received an endotracheal injection of an equal volume of saline. Two shots of hUC-MSC (2.5 x 105 in 200 &#181;L of sterile saline) were infused into the mouse tail vein, 24 h and 7 days after the bleomycin administration. Control animals received an intravenous infusion of an equal volume of sterile saline. Mice were sacrifice...

Watch this Scientific Journal Video about Induction of Mouse Lung Injury by Endotracheal Injection of Bleomycin at JoVE.com

Induction of Mouse Lung Injury by Endotracheal Injection of Bleomycin

Here we present an effective method to investigate the antifibrotic activity of intravenously infused human mesenchymal stromal cells obtained from the whole umbilical cord following the induction of lung injury by an endotracheal injection of bleomycin in C57BL/6 mice. This protocol can be easily extended to the preclinical testing of other therapeutics.

Pulmonary fibrosis is a hallmark of several human lung diseases with a different etiology. Since current therapies are rather limited, mouse models ...

This protocol can be successfully applied both to induce important inflammatory and fibrotic response in both lungs by endotracheal injection of Bleomycin and to validate new anti-inflammatory and anti-fibrotic systemic therapies by tail vein infusion. The main advantage of this technique is that direct injection of Bleomycin into the mouse trachea ensures rapid targeting of the lungs without any spills in the upper airway allowing safe, robust and reproducible induction of lung inflammatory and fibrosis. Demonstrating the procedure will be Dr.Fiorenza Orlando, a veterinary doctor from our collaborating laboratory.To begin, position the anesthetized mouse lying on its back on a surgical platform. Delicately fix its legs with surgical tape strips to hold it in place. To hyper extend the neck of the mouse, place a support such as dental cotton roll under its cervical region.Then use a razor blade to gently shave the throat. Use a pair of anatomical forceps to pinch the skin. Use a pair of ring handled curved blunt scissors to make a short incision about half a centimeter in length in correspondence to the mouse sternohyoid muscle.Use cotton wool sticks to stop any bleeding. Then exteriorize the trachea by blunt dissection and gently clean it from fat and other tissues. Rotate the surgical platform to orient the mouse with its head towards the operator which allows the operator during the injection to angle the syringe properly.To visualize the trachea, place the mouse under an operating microscope. Adjust illumination and set magnification between 1 and 1.2 then adjust the focus and sharpness. The trachea can be easily distinguished as a white translucent tube with clearly visible tracheal rings.Gently pipette to mix the Bleomycin solution and aspirate 100 microliters into a 0.5 milliliter syringe with a 25 gauge needle avoiding bubble formation. Once the trachea is clearly visualized, carefully puncture it with the needle tip at a 30 degree angle. Slowly inject 100 microliters of Bleomycin directly into the lumen of the trachea.After waiting a few seconds for the entire volume to travel down the needle, remove it from the trachea. Observe a few seconds of apnea occurring when the needle is correctly inserted into the trachea indicating that the entire volume of liquid has been inhaled. Safely discard the syringe and needle.Close the subcutaneous fascia and the skin wound with a 5-0 absorbable suture and allow the animal to recover. After anesthetizing the mouse again and once unconsciousness has been confirmed, place the mouse under a sterile hood. Use a facial mask with a continuous flow of 1.5%isoflurane to maintain gentle anesthesia throughout the experiment.To promote vasodilation and allow for easier injection, soak the tail in warm water for two minutes. Mix a suspension of human umbilical cord mesenchymal stromal cells by gently pipetting to avoid cell clump formation. Aspirate 200 microliters into a one milliliter syringe with a 26 gauge needle avoiding bubble formation.Hold the tail by the tip and gently straighten it. Then locate the lateral vein of the tail. Gently scrape the tail with a scalpel and wipe it with 70%ethanol.Starting from the distal portion of the tail, insert the needle into the vein at a 15 degree angle. Slowly infuse 200 microliters of human umbilical cord mesenchymal stromal cells. To monitor successful intravenous infusion, observe the liquid entering the vein without resistance and a lack of extravasation.After waiting a few seconds until the entire volume travels down the needle, remove it from the vein. Then briefly apply pressure to the entry wound with a sterile gauze to prevent bleeding and allow the animal to recover. Safely discard the syringe and the needle after the infusion.After Bleomycin injection, lung histopathological changes were assessed by Hematoxylin and Eosin and Picrosirius Red staining confirming extensive inflammatory infiltration and fibrosis compared to normal lung architecture after saline injection. Bleomycin-induced lung inflammation and fibrosis were largely attenuated by human umbilical cord mesenchymal stromal cell infusion but not by saline. Collagen deposition was measured by hydroxyproline assay.Following Bleomycin injection, hydroxyproline levels progressively increased from day eight to day 14 and 21. Whereas the addition of human umbilical cord mesenchymal stromal cells significantly reduced the effects of Bleomycin. Expression levels of Col1A1 type one collagen gene in whole lung mRNA also showed a progressive increase at days eight, 14 and 21 which was partially reduced by human umbilical cord mesenchymal stromal cell treatment.Immunostaining with specific antibodies showed that infused human umbilical cord mesenchymal stromal cells rapidly and effectively reached mouse lungs, although only a few cells were detected. These data suggest a rapid dislocation of the cells from the site injury despite the prolonged protective effect. The use of an operating microscope ensures high confidence of success by allowing the operator to accurately monitor correct placement of the needle into the mouse trachea prior to installation, thus minimizing the risk of damaging it.

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Immunology and Infection

16.7K Views.  Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS)-Istituto Nazionale Ricovero e Cura Anziani (INRCA). This protocol can be successfully applied both to induce important inflammatory and fibrotic response in both lungs by endotracheal injection of Bleomycin and to validate new anti-inflammatory and anti-fibrotic systemic therapies by tail vein infusion. The main advantage of this technique is that direct injection of Bleomycin into the mouse trachea ensures rapid targeting of the lungs without any spills in the upper airway allowing safe, robust and reproducible induction of lung inflammatory ...