Name: a standardized method for measuring internal lung surface area via mouse pneumonectomy and prosthesis implantation
Uploaded: 2017-07-26T15:00:00
Description: Watch this Scientific Journal Video about A Standardized Method for Measuring Internal Lung Surface Area via Mouse Pneumonectomy and Prosthesis Implantation at JoVE.com

The authors would like to acknowledge the National Institute of Biological Sciences, Beijing for the assistance. This work was supported by Beijing Municipal Natural Science Foundation (No. Z17110200040000).

All procedures used in this protocol were carried out in accordance with the recommendations in the Guidelines for the Care and Use of Laboratory Animals of the National Institute of Biological Sciences, Beijing. 8 week-old CD-1 male mice were housed in a specific pathogen free (SPF) facility until the experiments were conducted. Surgeries were performed using completely anesthetized mice (i.e., without any toe pinch responses). After surgery, mice were kept in a warm, humid room with sufficient food and fresh w...

<ol>
	<li>Liu, Z., 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=MAPK-Mediated+YAP+Activation+Controls+Mechanical-Tension-Induced+Pulmonary+Alveolar+Regeneration.">MAPK-Mediated YAP Activation Controls Mechanical-Tension-Induced Pulmonary Alveolar Regeneration.</a> Cell Rep. 16 (7), 1810-1819 (2016).</li><li>Thurlbeck, W. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Internal+surface+area+and+other+measurements+in+emphysema.">Internal surface area and other measurements in emphysema.</a> Thorax. 22 (6), 483-496 (1967).</li><li>Knudsen, L., Weibel, E. R., Gundersen, H. J. G., Weinstein, F. V., Ochs, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assessment+of+air+space+size+characteristics+by+intercept+(chord)+measurement:+an+accurate+and+efficient+stereological+approach.">Assessment of air space size characteristics by intercept (chord) measurement: an accurate and efficient stereological approach.</a> J Appl Physiol. 108 (2), 412-421 (2010).</li><li>Weibel, E. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Morphometry of the Human Lung. , (1963).</li><li>Duguid, J. B., Young, A., Cauna, D., Lambert, M. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+internal+surface+area+of+the+lung+in+emphysema.">The internal surface area of the lung in emphysema.</a> J Pathol Bacteriol. 88, 405-421 (1964).</li><li>Branchfield, K., 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=Pulmonary+neuroendocrine+cells+function+as+airway+sensors+to+control+lung+immune+response.">Pulmonary neuroendocrine cells function as airway sensors to control lung immune response.</a> Science. 351 (6274), 707-710 (2016).</li><li>Ding, B. -. S., 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=Endothelial-derived+angiocrine+signals+induce+and+sustain+regenerative+lung+alveolarization.">Endothelial-derived angiocrine signals induce and sustain regenerative lung alveolarization.</a> Cell. 147 (3), 539-553 (2011).</li><li>Dunnill, M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+methods+in+the+study+of+pulmonary+pathology.">Quantitative methods in the study of pulmonary pathology.</a> Thorax. 17 (4), 320-328 (1962).</li><li>Weibel, E. R., Gomez, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Architecture+of+the+human+lung.+Use+of+quantitative+methods+establishes+fundamental+relations+between+size+and+number+of+lung+structures.">Architecture of the human lung. Use of quantitative methods establishes fundamental relations between size and number of lung structures.</a> Science. 137 (3530), 577-585 (1962).</li><li>Thurlbeck, W. 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+internal+surface+area+of+nonemphysematous+lungs.">The internal surface area of nonemphysematous lungs.</a> Am Rev Respir Dis. 95 (5), 765-773 (1967).</li><li>Butler, J. P., 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=Evidence+for+adult+lung+growth+in+humans.">Evidence for adult lung growth in humans.</a> N Engl J Med. 367 (16), 244-247 (2012).</li><li>Hsia, C. C. W., Herazo, L. F., Fryder-Doffey, F., Weibel, E. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Compensatory+lung+growth+occurs+in+adult+dogs+after+right+pneumonectomy.">Compensatory lung growth occurs in adult dogs after right pneumonectomy.</a> J Clin Invest. 94 (1), 405-412 (1994).</li><li>Thurlbeck, S. W. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pneumonectomy+in+Rats+at+Various+Ages.">Pneumonectomy in Rats at Various Ages.</a> Am Rev Respir Dis. 120 (5), 1125-1136 (1979).</li><li>Cagle, P. T., Langston, C., Thurlbeck, W. 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+Effect+of+Age+on+Postpneumonectomy+Growth+in+Rabbits.">The Effect of Age on Postpneumonectomy Growth in Rabbits.</a> Pediatr Pulmonol. 5 (2), 92-95 (1988).</li><li>Langston, C., 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=Alveolar+multiplication+in+the+contralateral+lung+after+unilateral+pneumonectomy+in+the+rabbit.">Alveolar multiplication in the contralateral lung after unilateral pneumonectomy in the rabbit.</a> Am Rev Respir Dis. 115 (1), 7-13 (1977).</li><li>Cohn, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Factors+Affecting+The+Postnatal+Growth+of+The+Lung.">Factors Affecting The Postnatal Growth of The Lung.</a> Anatomical Record. 75 (2), 195-205 (1939).</li><li>Hsia, C. C., Wu, E. Y., Wagner, E., Weibel, E. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preventing+mediastinal+shift+after+pneumonectomy+impairs+regenerative+alveolar+tissue+growth.">Preventing mediastinal shift after pneumonectomy impairs regenerative alveolar tissue growth.</a> Am J Physiol Lung Cell Mol Physiol. 281 (5), L1279-L1287 (2001).</li><li>Das, S., MacDonald, K., Chang, H. -. Y. S., Mitzner, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+simple+method+of+mouse+lung+intubation.">A simple method of mouse lung intubation.</a> J Vis Exp. (73), e50318 (2013).</li><li>Liu, S., Cimprich, J., Varisco, B. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mouse+pneumonectomy+model+of+compensatory+lung+growth.">Mouse pneumonectomy model of compensatory lung growth.</a> J Vis Exp. (94), (2014).</li><li>Silva, M. F. R., Zin, W. A., Saldiva, P. H. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Airspace+configuration+at+different+transpulmonary+pressures+in+normal+and+paraquat-induced+lung+injury+in+rats.">Airspace configuration at different transpulmonary pressures in normal and paraquat-induced lung injury in rats.</a> Am J Respir Crit Care Med. 158 (4), 1230-1234 (1998).</li><li>Yilmaz, C., 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=Noninvasive+quantification+of+heterogeneous+lung+growth+following+extensive+lung+resection+by+high-resolution+computed+tomography.">Noninvasive quantification of heterogeneous lung growth following extensive lung resection by high-resolution computed tomography.</a> J Appl Physiol. 107 (5), 1569-1578 (2009).</li><li>Voswinckel, R., 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=Characterisation+of+post-pneumonectomy+lung+growth+in+adult+mice.">Characterisation of post-pneumonectomy lung growth in adult mice.</a> Eur Respir J. 24 (4), 524-532 (2004).</li><li>Ravikumar, P., 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=Regional+Lung+Growth+and+Repair+Regional+lung+growth+following+pneumonectomy+assessed+by+computed+tomography.">Regional Lung Growth and Repair Regional lung growth following pneumonectomy assessed by computed tomography.</a> J Appl Physiol. 97, 1567-1574 (2004).</li><li>Gibney, B. C., 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=Detection+of+murine+post-pneumonectomy+lung+regeneration+by+18FDG+PET+imaging.">Detection of murine post-pneumonectomy lung regeneration by 18FDG PET imaging.</a> EJNMMI Res. 2 (1), (2012).</li><li>Mu&#241;oz-Barrutia, A., Ceresa, M., Artaechevarria, X., Montuenga, L. M., Ortiz-De-Solorzano, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantification+of+lung+damage+in+an+elastase-induced+mouse+model+of+emphysema.">Quantification of lung damage in an elastase-induced mouse model of emphysema.</a> Int J Biomed Imaging. 2012, (2012).</li></ol>

In this protocol, we provide detailed descriptions about the measurement of pulmonary parameters after mouse left lung PNX and prosthesis implantation. ISA is now considered to be a key metric for the assessment of respiratory function in many pulmonary diseases and in injury-induced alveolar regeneration. However, although the pulmonary research community is in agreement about the utility of ISA as a useful metric, to date, there has been little consideration of the standardization of the measurement of ILV and MLI, the...

The fundamental function of the lung is the exchange of oxygen and carbon dioxide between blood vessels and the atmosphere. Lung diseases such as bronchopulmonary dysplasia (BPD), chronic obstructive pulmonary disease (COPD), and acute respiratory infections, result in decreased ISA2. Researchers studying lung disease have developed several quantitative methods to evaluate morphological changes in lungs, including MLI, ILV, number of gas exchange units, ISA, and lung tissue compliance2,3. Pioneering studies by Weibel et al.4 and Duguid et al.5 together established that ISA can be used as a direct measure of lung gas-exchange capacity in human lungs and can be used as a criterion to determine emphysema severity. A number of studies published in the last five years have used lung morphological parameters (e.g., ISA and MLI) to assess morphological and functional changes in the lungs of mice during development6 and during recovery from injury PNX1,7. ISA is calculated using Equation 18,9:
<img alt="Equation" src="/files/ftp_upload/56114/56114eq1.jpg" />
, where ILV is the internal lung volume and MLI is an intermediary parameter that represents the pulmonary peripheral airspace size10.
PNX, the surgical removal of one or more lung lobes, has been widely reported to induce alveolar regeneration in many species, including humans11, mice1, dogs12, rats13, and rabbits14,15. A study of mice lungs at fourteen days post-PNX showed that both the expansion of pre-existing alveoli and the de novo formation of alveoli contribute to the restoration of ISA, ILV, and the number of alveoli in the remaining lung tissues1. We and others have shown that the insertion of materials such as sponge, wax, or a custom-shaped prosthesis into the empty thoracic cavity following PNX (i.e., prosthesis implantation) impairs alveolar regeneration. It is now firmly established that mechanical force functions as one of the most important factors for initiating alveolar regeneration1,16,17. Such studies have highlighted the effectiveness of using ISA values from PNX-treated and Prosthesis-implanted lungs as a criterion to quantitatively evaluate alveolar regeneration.
Observer bias is known to significantly influence measured values for lung morphological parameters (e.g., MIL and ILV). Standardized protocols can be used to obviate this bias in determining both ILV and MLI, which are the two parameters used in the calculation of ISA. Here, we provide highly-detailed, standardized protocols for measuring these lung parameters. Importantly, the ability to accurately quantify ISA promises to improve the reliability and reproducibility of studies of lung function in injury-induced alveolar regeneration models and should facilitate mechanistic discoveries in multiple pulmonary diseases.

<table width="881">
	<tbody>
		<tr height="21">
			<td height="21" style="width:411px;height:21px;">Low cost cautery kit</td>
			<td style="width:167px;">Fine Science Tools</td>
			<td style="width:136px;">18010-00</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Noyes scissors</td>
			<td>Fine Science Tools</td>
			<td>15012-12</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Standard pattern forceps</td>
			<td>Fine Science Tools</td>
			<td>11000-12</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Castroviejo Micro Needle Holders</td>
			<td>Fine Science Tools</td>
			<td>12060-01</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Vessel clips</td>
			<td>Fine Science Tools</td>
			<td>18374-44</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">I. V. Cannula-20 gauge</td>
			<td>Jinhuan Medical Product Co., LTD.</td>
			<td>29P0601</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Surgical suture</td>
			<td>Jinhuan Medical Product Co., LTD.</td>
			<td>F602</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Mouse intubation platform</td>
			<td>Penn-Century, Inc</td>
			<td>Model MIP</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Small Animal Laryngoscope</td>
			<td>Penn-Century, Inc</td>
			<td>Model LS-2-M</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">TOPO Small Animal Ventilator</td>
			<td>Kent Scientific</td>
			<td>RSP1006-05L</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Thermal pad</td>
			<td>Stuart equipment</td>
			<td>SBH130D</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Pentobarbital sodium salt</td>
			<td>Sigma</td>
			<td>P3761</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Heparin sodium salt</td>
			<td>Sigma</td>
			<td>H3393</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Hematoxylin Solution</td>
			<td>Sigma</td>
			<td>GHS132</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Eosin Y solution, alcoholic</td>
			<td>Sigma</td>
			<td>HT110116</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">10 ml Pipette</td>
			<td>Thermo Scientific</td>
			<td>170356</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Paraformaldehyde</td>
			<td>Sigma</td>
			<td>P6148</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">O.C.T Compound</td>
			<td>Tissue-Tek</td>
			<td>4583</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">cryosection machine</td>
			<td>Leica</td>
			<td>CM1950</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Disposable Base Molds</td>
			<td>Fisher HealthCare</td>
			<td>22-363-553</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">18 gauge needle</td>
			<td>Becton Dickinson</td>
			<td>305199</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Povidone iodine</td>
			<td>Fisher Scientific</td>
			<td>19-027132</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">70% ethanol</td>
			<td>Fisher Scientific</td>
			<td>BP82011</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Infusion sets for single use</td>
			<td>Weigao</td>
			<td>SFDA 2012 3661704</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Phosphate buffered saline</td>
			<td>Gibco</td>
			<td align="right">10010023</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Tapes</td>
			<td>3M Scotch</td>
			<td style="width:136px;">8915</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cotton pad</td>
			<td>Vinda</td>
			<td>Dr.P</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Silicone prosthesis</td>
			<td>Custom made</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Brightfield microscope</td>
			<td>Olympus</td>
			<td>VS120</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Ruler tool</td>
			<td>Adobe Photoshop</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

a standardized method for measuring internal lung surface area via mouse pneumonectomy and prosthesis implantation

Pulmonary morphology, physiology, and respiratory functions change in both physiological and pathological conditions. Internal lung surface area (ISA), representing the gas-exchange capacity of the lung, is a critical criterion to assess respiratory function. However, observer bias can significantly influence measured values for lung morphological parameters. The protocol that we describe here minimizes variations during measurements of two morphological parameters used for ISA calculation: internal lung volume (ILV) and mean linear intercept (MLI). Using ISA as a morphometric and functional parameter to determine the outcome of alveolar regeneration in both pneumonectomy (PNX) and prosthesis implantation mouse models, we found that the increased ISA following PNX treatment was significantly blocked by implantation of a prosthesis into the thoracic cavity1. The ability to accurately quantify ISA is not only expected to improve the reliability and reproducibility of lung function studies in injured-induced alveolar regeneration models, but also to promote mechanistic discoveries of multiple pulmonary diseases.

We performed here an experiment with a PNX-treated group and a prosthesis implantation (Prosthesis-implanted) group. These groupings are the same as the groupings used in a previously-published study from our research group14.
The mouse PNX and prosthesis implantation procedures are shown in Figure 2. 8 week-old CD-1 male mice are used for the surgeries and for the quantifica...

Watch this Scientific Journal Video about A Standardized Method for Measuring Internal Lung Surface Area via Mouse Pneumonectomy and Prosthesis Implantation at JoVE.com

A Standardized Method for Measuring Internal Lung Surface Area via Mouse Pneumonectomy and Prosthesis Implantation

Internal lung surface area (ISA) is a critical criterion for assessing lung morphology and physiology in lung diseases and injury-induced alveolar regeneration. We describe here a standardized method that can minimize the measurement bias for ISA in both lung pneumonectomy and prosthesis implantation mouse models.

Pulmonary morphology, physiology, and respiratory functions change in both physiological and pathological conditions. Internal lung surface area (ISA), ...

The overall goal of this procedure is to accurately measure the internal surface area of a mouse lung after pneumonectomy and prosthesis implantation. This method helps to analyze the morphological and the physiological functions of the lung in mechanical force-induced adult lung regeneration. The main advantage of this technique is to accurately quantify internal lung surface area, which promise to increase the reliability and the reproducibility of lung function status.Prepare the mouse for surgery on an intubation platform with its ventral side accessible. Then pull out the tongue and inspect the vocal chords with a small animal laryngoscope that is compatible with guiding catheters. Then gently insert a 20 gauge intravenous intubation canula into the trachea at an interior angle.Next, put the mouse in a right lateral recumbent position and connect the canula to a mechanical ventilator. Observe the chest to judge the insertion of the canula into the trachea. Set the inspiratory pressure to 12 centimeters of water and set the respiratory rate to 120 breaths per minute.Now, clean the exposed skin with at least three alternating scrubs of Betadine and 70%ethanol. Then begin the surgery with a two to three centimeter posterolateral thoracotomy incision into the fifth intercostal space. Penetrate the musculature using Noyes spring scissors.Next, make a 1.5 centimeter incision to expose the left lung. As needed throughout the surgery, use a high temperature cauterizer to stop bleeding. Then, lift 1/3 of the left lung lobe from the chest with blunt tip forceps, and use a cotton swab to pull out the entire left lung.Now, identify the pulmonary artery and bronchi of the left lung lobe, and tightly ligate the bronchi and vessels at the hilum with a soaked surgical suture. Next, cut out the left lung lobe three to four millimeters from the ligation, being careful not to cut off the suture, which could result in pneumothorax. Next, close the chest wall with one suture.Then, stitch the muscle layer and the skin layer sequentially, using five to six interrupted sutures with three to four millimeter gaps. Be sure to keep the surgical suture needle away from the heart. Cardiac puncture is lethal.Lastly, disinfect the surgical area with povidone-iodine. Then, place the mouse on a 38 degrees Celsius thermal pad. Keep using the ventilator until spontaneous breathing returns.Perform the previously described operation, but just after removing the lung, prepare to insert the prosthesis. Using blunted forceps, grip the center of the ellipsoid silicone prothesis. Next, while holding the rib with forceps to expose the thoracic cavity, very gently insert the prothesis.Enter at a 45 degree angle between the frontal plane of the prosthesis and the thoracic surface. Using blunt forceps, ensure that the prosthesis is fully within the left empty thoracic cavity. Now, close the chest and monitor the mouse as previously described.For this procedure, assemble a custom inflation tube that consists of a plunger removed from a 10 milliliter serological pipette, a 40 centimeter long flexible tube with a needle adapter, a flow rate control valve, and an 18 gauge needle. Once assembled, secure the pipette to a sideboard with tape. The distance between the top of the pipette and the bench must be at least 30 centimeters.After euthanizing the mouse by anesthetic injection, secure it to a sterilized board and carefully open the chest to cut out the sternum and expose the lung lobes. Then, expose the trachea. Next, fill the inflation tube with freshly made 4%PFA and remove all the bubbles from the tube.Then, insert the needle into the trachea. To avoid leakage, clip the trachea with vessel clips. Now, inflate the lung with fixative at a constant transpulmonary pressure of 25 centimeters of water.Incubate the lungs at room temperature for two hours for full expansion. After the inflation, take note of the volume displacement of fixative. Now, ligate the trachea and gently dissect out the lungs intact from the surrounding connective tissues.Use scissors and be very gentle. Next, incubate the lungs in a 50 milliliter conical tube filled with 4%PFA for 12 hours at four degrees Celsius with gentle shaking on a shaker. Then proceed with processing and staining as described in the text protocol.To quantify the MLI, use images of the agent used in sections collected under bright-field at 20x magnification. From three different lung sections, randomly select a total of 15 non-overlapping views, each about one square millimeter, and then vent them. Only use areas without arteries and veins, major airways, or alveolar ducts.For the analysis, draw a 10 by 10 grid over each selected area using a ruler tool. The grid lines are thus about 100 microns apart. Then, to find an intercept along the line as the length between two adjacent alveolar epithelia.For example, the double-headed arrows illustrate the lengths. Count all these lengths along each grid line, and the MLI is the average value of the intercept lengths. Using the described protocols, PNX-treated mice were compared with prosthetic implanted mice.The mice used were eight-week-old CD-1 males, and their left lung lobes were resected. The prosthesis mimics the size and shape of the left lung lobe and was inserted into the chest after the left lung lobe was removed. 14 days after the surgery, a custom made inflation tube was used to determine the internal volume of the remaining right lung.The average volume of the right lung in the five PNX-treated mice was approximately 1.4 milliliters, which was significantly greater, 1.05 milliliters for the five prosthesis-implanted mice. The MLI values in the remaining right lungs were significantly greater as well. Using these parameters, the internal lung surface area was calculated and was found to be significantly smaller in the prosthesis-implanted mice.After watching this video, you should have a good understanding of how to calculate the internal lung surface area for the mechanical force-induced alveolar regeneration mouse model.

a-standardized-method-for-measuring-internal-lung-surface-area-via

Research

JoVE Journal

Developmental Biology

Microbead Implantation in the Zebrafish Embryo

The zebrafish has emerged as a valuable genetic model system for the study of developmental biology and disease. Zebrafish share a high degree of genomic conservation, as well as similarities in cellular, molecular, and physiological processes, with other vertebrates including humans. During early ontogeny, zebrafish embryos are optically transparent, allowing researchers to visualize the dynamics of organogenesis using a simple stereomicroscope. Microbead implantation is a method that enables tissue manipulation through the alteration of factors in local environments. This allows researchers to assay the effects of any number of signaling molecules of interest, such as secreted peptides, at specific spatial and temporal points within the developing embryo. Here, we detail a protocol for how to manipulate and implant beads during early zebrafish development.

The zebrafish is an excellent model system for genetic and developmental studies. Bead implantation is a valuable tissue manipulation technique that can be used to interrogate developmental mechanisms by introducing alterations in local cellular environments. This protocol describes how to perform microbead implantation in the zebrafish embryo.

The zebrafish has emerged as a valuable genetic model system for the study of developmental biology and disease. Zebrafish share a high degree of genomic ...

Method of Studying Palatal Fusion using Static Organ Culture

Cleft lip and palate are among the most common of all birth defects. The secondary palate forms from mesenchymal shelves covered with epithelium that adheres to form the midline epithelial seam (MES). The theories suggest that MES cells follow an epithelial to mesenchymal transition (EMT), apoptosis and migration, making a fused palate 1. Complete disintegration of the MES is the final essential phase of palatal confluence with surrounding mesenchymal cells. We provide a method for palate organ culture. The developed in vitro protocol allows the study of the biological and molecular processes during fusion. The applications of this technique are numerous, including evaluating responses to exogenous chemical agents, effects of regulatory and growth factors and specific proteins. Palatal organ culture has a number of advantages including manipulation at different stages of development that is not possible using in vivo studies.

Studies of palate development are motivated by the incidence of cleft palate, a birth defect that imposes a tremendous health burden and can leave lasting disfigurement. We demonstrate here a technique to culture palatal shelves that can be used to study different signaling pathways involved in palatal development and fusion.

Cleft lip and palate are among the most common of all birth defects. The secondary palate forms from mesenchymal shelves covered with epithelium that ...

Production and Administration of Therapeutic Mesenchymal Stem/Stromal Cell (MSC) Spheroids Primed in 3-D Cultures Under Xeno-free Conditions

Mesenchymal stem/stromal cells (MSCs) hold great promise in bioengineering and regenerative medicine. MSCs can be isolated from multiple adult tissues via their strong adherence to tissue culture plastic and then further expanded in vitro, most commonly using fetal bovine serum (FBS). Since FBS can cause MSCs to become immunogenic, its presence in MSC cultures limits both clinical and experimental applications of the cells. Therefore, studies employing chemically defined xeno-free (XF) media for MSC cultures are extremely valuable. Many beneficial effects of MSCs have been attributed to their ability to regulate inflammation and immunity, mainly through secretion of immunomodulatory factors such as tumor necrosis factor-stimulated gene 6 (TSG6) and prostaglandin E2 (PGE2). However, MSCs require activation to produce these factors and since the effect of MSCs is often transient, great interest has emerged to discover ways of pre-activating the cells prior to their use, thus eliminating the lag time for activation in vivo. Here we present protocols to efficiently activate or prime MSCs in three-dimensional (3D) cultures under chemically defined XF conditions and to administer these pre-activated MSCs in vivo. Specifically, we first describe methods to generate spherical MSC micro-tissues or &#39;spheroids&#39; in hanging drops using XF medium and demonstrate how the spheres and conditioned medium (CM) can be harvested for various applications. Second, we describe gene expression screens and in vitro functional assays to rapidly assess the level of MSC activation in spheroids, emphasizing the anti-inflammatory and anti-cancer potential of the cells. Third, we describe a novel method to inject intact MSC spheroids into the mouse peritoneal cavity for in vivo efficacy testing. Overall, the protocols herein overcome major challenges of obtaining pre-activated MSCs under chemically defined XF conditions and provide a flexible system to administer MSC spheroids for therapies.

Production and Administration of Therapeutic Mesenchymal Stem/Stromal Cell MSC Spheroids Primed in 3-D Cultures Under Xeno-free Conditions

The therapeutic potential of mesenchymal stem/stromal cells (MSCs) is well-documented, however the best method of preparing the cells for patients remains controversial. Herein, we communicate protocols to efficiently generate and administer therapeutic spherical aggregates or 'spheroids' of MSCs primed under xeno-free conditions for experimental and clinical applications.

Mesenchymal stem/stromal cells (MSCs) hold great promise in bioengineering and regenerative medicine. MSCs can be isolated from multiple adult tissues via ...

Isolation and Enrichment of Liver Progenitor Subsets Identified by a Novel Surface Marker Combination

During chronic liver injuries, progenitor cells expand in a process called ductular reaction, which also entails the appearance of inflammatory cellular infiltrate and epithelial cell activation. The progenitor cell population during such inflammatory reactions has mostly been investigated using single surface markers, either by histological analysis or by flow cytometry-based techniques. However, novel surface markers identified various functionally distinct subsets within the liver progenitor/stem cell compartment. The method presented here describes the isolation and detailed flow cytometry analysis of progenitor subsets using novel surface marker combinations. Moreover, it demonstrates how the various progenitor cell subsets can be isolated with high purity using automated magnetic and FACS sorting-based methods. Importantly, novel and simplified enzymatic dissociation of the liver allows for the isolation of these rare cell populations with a high viability that is superior in comparison to other existing methods. This is especially relevant for further studying progenitor cells in vitro or for isolating high-quality RNA to analyze the gene expression profile.

Liver injuries are accompanied by progenitor cell expansion that represents a heterogeneous cell population. Novel classification of this cellular compartment allows for the distinguishing of multiple subsets. The method described here illustrates the flow cytometry analysis and high purity isolation of various subsets that can be used for further assays.

During chronic liver injuries, progenitor cells expand in a process called ductular reaction, which also entails the appearance of inflammatory cellular ...

Assessing Cardiomyocyte Subtypes Following Transcription Factor-mediated Reprogramming of Mouse Embryonic Fibroblasts

Direct reprogramming of one cell type into another has recently emerged as a powerful paradigm for regenerative medicine, disease modeling, and lineage specification. In particular, the conversion of fibroblasts into induced cardiomyocyte-like myocytes (iCLMs) by Gata4, Hand2, Mef2c, and Tbx5 (GHMT) represents an important avenue for generating de novo cardiac myocytes in vitro and in vivo. Recent evidence suggests that GHMT generates a greater diversity of cardiac subtypes than previously appreciated, thus underscoring the need for a systematic approach to conducting additional studies. Before direct reprogramming can be used as a therapeutic strategy, however, the mechanistic underpinnings of lineage conversion must be understood in detail to generate specific cardiac subtypes. Here we present a detailed protocol for generating iCLMs by GHMT-mediated reprogramming of mouse embryonic fibroblasts (MEFs). 
We outline methods for MEF isolation, retroviral production, and MEF infection to accomplish efficient reprogramming. To determine the subtype identity of reprogrammed cells, we detail a step-by-step approach for performing immunocytochemistry on iCLMs using a defined set of compatible antibodies. Methods for confocal microscopy, identification, and quantification of iCLMs and individual atrial (iAM), ventricular (iVM), and pacemaker (iPM) subtypes are also presented. Finally, we discuss representative results of prototypical direct reprogramming experiments and highlight important technical aspects of our protocol to ensure efficient lineage conversion. Taken together, our optimized protocol should provide a stepwise approach for investigators to conduct meaningful cardiac reprogramming experiments that require identification of individual CM subtypes.

This manuscript describes a step-by-step protocol for the generation and quantification of diverse reprogrammed cardiac subtypes using a retrovirus-mediated delivery of Gata4, Hand2, Mef2c, and Tbx5.

Direct reprogramming of one cell type into another has recently emerged as a powerful paradigm for regenerative medicine, disease modeling, and lineage ...

A Standardized Approach for Multispecies Purification of Mammalian Male Germ Cells by Mechanical Tissue Dissociation and Flow Cytometry

Fluorescence-activated cell sorting (FACS) has been one of the methods of choice to isolate enriched populations of mammalian testicular germ cells. Currently, it allows the discrimination of up to 9 murine germ cell populations with high yield and purity. This high-resolution in discrimination and purification is possible due to unique changes in chromatin structure and quantity throughout spermatogenesis. These patterns can be captured by flow cytometry of male germ cells stained with fluorescent DNA-binding dyes such as Hoechst-33342 (Hoechst). Herein is a detailed description of a recently developed protocol to isolate mammalian testicular germ cells. Briefly, single cell suspensions are generated from testicular tissue by mechanical dissociation, double stained with Hoechst and propidium iodide (PI) and processed by flow cytometry. A serial gating strategy, including the selection of live cells (PI negative) with different DNA content (Hoechst intensity), is used during FACS sorting to discriminate up to 5 germ cell types. These include, with corresponding average purities (determined by microscopy evaluation): spermatogonia (66%), primary (71%) and secondary (85%) spermatocytes, and spermatids (90%), further separated into round (93%) and elongating (87%) subpopulations. Execution of the entire workflow is straightforward, allows the isolation of 4 cell types simultaneously with the appropriate FACS machine, and can be performed in less than 2 h. As reduced processing time is crucial to preserve the physiology of ex vivo cells, this method is ideal for downstream high-throughput studies of male germ cell biology. Moreover, a standardized protocol for multispecies purification of mammalian germ cells eliminates methodological sources of variables and allows a single set of reagents to be used for different animal models.

This work describes the standardization of a method to obtain purified germ cell populations from testicular tissue of different mammalian species. It is a straightforward protocol that combines mechanical testis dissociation, staining with Hoechst-33342 and propidium iodide, and FACS sorting, with wide applications in comparative studies of male reproductive biology.

Fluorescence-activated cell sorting (FACS) has been one of the methods of choice to isolate enriched populations of mammalian testicular germ cells. ...

A Method for Characterizing Embryogenesis in Arabidopsis

Given the highly predictable nature of their development, Arabidopsis embryos have been used as a model for studies of morphogenesis in plants. However, early stage plant embryos are small and contain few cells, making them difficult to observe and analyze. A method is described here for characterizing pattern formation in plant embryos under a microscope using the model organism Arabidopsis. Following the clearance of fresh ovules using Hoyer's solution, the cell number in and morphology of embryos could be observed, and their developmental stage could be determined by differential interference contrast microscopy using a 100X oil immersion lens. In addition, the expression of specific marker proteins tagged with Green Fluorescent Protein (GFP) was monitored to annotate cell identity specification during embryo patterning by confocal laser scanning microscopy. Thus, this method can be used to observe pattern formation in wild-type plant embryos at the cellular and molecular levels, and to characterize the role of specific genes in embryo patterning by comparing pattern formation in embryos from wild-type plants and embryo-lethal mutants. Therefore, the method can be used to characterize embryogenesis in Arabidopsis.

A Method for Characterizing Embryogenesis in Arabidopsis

This protocol outlines a method for observing embryogenesis in Arabidopsis via ovule clearance followed by the inspection of embryo pattern formation under a microscope.

Given the highly predictable nature of their development, Arabidopsis embryos have been used as a model for studies of morphogenesis in plants. However, ...

A Novel Use of Three-dimensional High-frequency Ultrasonography for Early Pregnancy Characterization in the Mouse

High-frequency ultrasonography (HFUS) is a common method to non-invasively monitor the real-time development of the human fetus in utero. The mouse is routinely used as an in vivo model to study embryo implantation and pregnancy progression. Unfortunately, such murine studies require pregnancy interruption to enable follow-up phenotypic analysis. To address this issue, we used three-dimensional (3-D) reconstruction of HFUS imaging data for early detection and characterization of murine embryo implantation sites and their individual developmental progression in utero. Combining HFUS imaging with 3-D reconstruction and modeling, we were able to accurately quantify embryo implantation site number as well as monitor developmental progression in pregnant C57BL6J/129S mice from 5.5 days post coitus (d.p.c.) through to 9.5 d.p.c. with the use of a transducer. Measurements included: number, location, and volume of implantation sites as well as inter-implantation site spacing; embryo viability was assessed by cardiac activity monitoring. In the immediate post-implantation period (5.5 to 8.5 d.p.c.), 3-D reconstruction of the gravid uterus in both mesh and solid overlay format enabled visual representation of the developing pregnancies within each uterine horn. As genetically engineered mice continue to be used to characterize female reproductive phenotypes derived from uterine dysfunction, this method offers a new approach to detect, quantify, and characterize early implantation events in vivo. This novel use of 3-D HFUS imaging demonstrates the ability to successfully detect, visualize, and characterize embryo-implantation sites during early murine pregnancy in a non-invasive manner. The technology offers a significant improvement over current methods, which rely on the interruption of pregnancies for gross tissue and histopathologic characterization. Here we use a video and text format to describe how to successfully perform ultrasounds of early murine pregnancy to generate reliable and reproducible data with reconstruction of the uterine form in mesh and solid 3-D images.

Mice are widely used to study gestational biology. However, pregnancy termination is required for such studies which precludes longitudinal investigations and necessitates the use of large numbers of animals. Therefore, we describe a non-invasive technique of high-frequency ultrasonography for early detection and monitoring of post-implantation events in the pregnant mouse.

High-frequency ultrasonography (HFUS) is a common method to non-invasively monitor the real-time development of the human fetus in utero. The mouse is ...

Partial Lobular Hepatectomy: A Surgical Model for Morphologic Liver Regeneration

Morphological organ regeneration following acute tissue loss is common among lower vertebrates, but is rarely observed in mammalian postnatal life. Adult liver regeneration after 70% partial hepatectomy results in hepatocyte hypertrophy with some replication in remaining lobes with restoration of metabolic activity, but with permanent loss of the injured lobe&#39;s morphology and architecture. Here, we detail a new surgical method in the neonate that leaves a physiologic environment conducive to regeneration. This model involves amputation of the left lobe apex and a subsequent conservative management regimen, and lacks the necessity for ligation of major liver vessels or chemical injury, leaving a physiologic environment where regeneration may occur. We extend this protocol to amputations on juvenile (P7-14) mice, during which the injured liver transitions from organ regeneration to compensatory growth by hypertrophy. The presented, brief 30 min protocol provides a framework to study the mechanisms of regeneration, its age-associated decline in mammals, and the characterization of putative hepatic stem or progenitors.

Here, we present a new method for partial resection of the left hepatic lobe in neonatal (day 0) mice. This new protocol is suitable for studying acute liver injury and injury response in the neonatal setting.

Morphological organ regeneration following acute tissue loss is common among lower vertebrates, but is rarely observed in mammalian postnatal life. Adult ...

Whole-mount Confocal Microscopy for Adult Ear Skin: A Model System to Study Neuro-vascular Branching Morphogenesis and Immune Cell Distribution

Here, we present a protocol of a whole-mount adult ear skin imaging technique to study comprehensive three-dimensional neuro-vascular branching morphogenesis and patterning, as well as immune cell distribution at a cellular level. The analysis of peripheral nerve and blood vessel anatomical structures in adult tissues provides some insights into the understanding of functional neuro-vascular wiring and neuro-vascular degeneration in pathological conditions such as wound healing. As a highly informative model system, we have focused our studies on adult ear skin, which is readily accessible for dissection. Our simple and reproducible protocol provides an accurate depiction of the cellular components in the entire skin, such as peripheral nerves (sensory axons, sympathetic axons, and Schwann cells), blood vessels (endothelial cells and vascular smooth muscle cells), and inflammatory cells. We believe this protocol will pave the way to investigate morphological abnormalities in peripheral nerves and blood vessels as well as the inflammation in the adult ear skin under different pathological conditions.

Here, we describe a high resolution whole-mount imaging method in the entire adult mouse ear skin, which enables us to visualize branching morphogenesis and patterning of peripheral nerves and blood vessels, as well as immune cell distribution.