Name: ischemic tissue injury in the dorsal skinfold chamber of the mouse: a skin flap model to investigate acute persistent ischemia
Uploaded: 2014-11-17T14:00:00
Description: Watch this Scientific Journal Video about Ischemic Tissue Injury in the Dorsal Skinfold Chamber of the Mouse: A Skin Flap Model to Investigate Acute Persistent Ischemia at JoVE.com

We thank Katharina Haberland for image editing. &#160;Funding: The senior author received a KKF Grant from the Technische Universit&#228;t M&#252;nchen to set up a new research laboratory.

NOTE: Prior to implementation of the presented model, the corresponding animal protection laws must be consulted and permission must be obtained from the local authorities. In this work, all experiments were performed in conformity with the guiding principles for research involving animals and the German legislation on protection of animals. The experiments were approved by the local animal care committee.
1. Animal Preparation and Surgical Elevation of the Flap
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<ol>
	<li>McFarlane, R., De Young, G., Henry, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+design+of+a+pedicle+flap+in+the+rat+to+study+necrosis+and+its+prevention.">The design of a pedicle flap in the rat to study necrosis and its prevention.</a> Plast Reconstr Surg. 35, 177-182 (1965).</li><li>Finseth, F., Cutting, 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+experimental+neurovascular+island+skin+flap+for+the+study+of+the+delay+phenomenon.">An experimental neurovascular island skin flap for the study of the delay phenomenon.</a> Plast Reconstr Surg. 61, 412-420 (1978).</li><li>Petry, J. J., Wortham, K. 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D. <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+microvascular+oxygen+supply+and+tissue+oxygenation+in+hepatic+ischemia/reperfusion.">Assessment of microvascular oxygen supply and tissue oxygenation in hepatic ischemia/reperfusion.</a> Adv. Exp. Med. Biol. 428, 403-408 (1997).</li><li>Menger, M. D., Barker, J. H., Messmer, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Capillary+blood+perfusion+during+postischemic+reperfusion+in+striated+muscle.">Capillary blood perfusion during postischemic reperfusion in striated muscle.</a> Plast Reconstr Surg. 89, 1104-1114 (1992).</li><li>Uhl, E., R&#246;sken, F., Curri, S. B., Menger, M. D., Messmer, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reduction+of+skin+flap+necrosis+by+transdermal+application+of+buflomedil+bound+to+liposomes.">Reduction of skin flap necrosis by transdermal application of buflomedil bound to liposomes.</a> Plast Reconstr Surg. 102, 1598-1604 (1998).</li><li>Pang, C. Y., Neligan, P., Nakatsuka, T., Sasaki, G. H. <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+the+fluorescein+dye+test+for+prediction+of+skin+flap+viability+in+pigs.">Assessment of the fluorescein dye test for prediction of skin flap viability in pigs.</a> J Surg Res. 41, 173-181 (1986).</li><li>Hjortdal, V. E., Hansen, E. S., Henriksen, T. B., Kjolseth, D., Soballe, K., Djurhuus, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+microcirculation+of+myocutaneous+island+flaps+in+pigs+studied+with+radioactive+blood+volume+tracers+and+microspheres+of+different+sizes.">The microcirculation of myocutaneous island flaps in pigs studied with radioactive blood volume tracers and microspheres of different sizes.</a> Plast Reconstr Surg. 89, 116-122 (1992).</li><li>Pang, C. Y., Neligan, P., Nakatsuka, T. <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+microsphere+technique+for+measurement+of+capillary+blood+flow+in+random+skin+flaps+in+pigs.">Assessment of microsphere technique for measurement of capillary blood flow in random skin flaps in pigs.</a> Plast Reconstr Surg. 74, 513-521 (1984).</li><li>Sandison, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+method+for+the+microscopic+study+of+living+growing+tissues+by+the+introduction+of+a+transparent+chamber+in+the+rabbit's+ear.">A new method for the microscopic study of living growing tissues by the introduction of a transparent chamber in the rabbit's ear.</a> The Anatomical Record. 28, 281-287 (1924).</li><li>Algire, G. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+Adaptation+of+the+Transparent-Chamber+Technique+to+the+Mouse.">An Adaptation of the Transparent-Chamber Technique to the Mouse.</a> Journal of the National Cancer Institute. 4, 1-11 (1943).</li><li>Lehr, H. A., Leunig, M., Menger, M. D., Nolte, D., Messmer, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dorsal+skinfold+chamber+technique+for+intravital+microscopy+in+nude+mice.">Dorsal skinfold chamber technique for intravital microscopy in nude mice.</a> Am J Pathol. 4, 1055-1062 (1993).</li><li>Barker, J. 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=An+animal+model+to+study+microcirculatory+changes+associated+with+vascular+delay.">An animal model to study microcirculatory changes associated with vascular delay.</a> Br J Plast Surg. 52, 133-142 (1999).</li><li>Erni, D., Sakai, H., Banic, A., Tschopp, H. M., Intaglietta, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+assessment+of+microhemodynamics+in+ischemic+skin+flap+tissue+by+intravital+microscopy.">Quantitative assessment of microhemodynamics in ischemic skin flap tissue by intravital microscopy.</a> Ann Plast Surg. 43, 405-414 (1999).</li><li>Roesken, F., Sch&#228;fer, T., Spitzer, W. J., Vollmar, B., Menger, M. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vivo+analysis+of+the+microcirculation+of+osteomyocutaneous+flaps+using+fluorescence+microscopy.">In vivo analysis of the microcirculation of osteomyocutaneous flaps using fluorescence microscopy.</a> Br J Plast Surg. 52, 644-652 (1999).</li><li>Harder, Y., Amon, M., Erni, D., Menger, M. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evolution+of+ischemic+tissue+injury+in+a+random+pattern+flap:+a+new+mouse+model+using+intravital+microscopy.">Evolution of ischemic tissue injury in a random pattern flap: a new mouse model using intravital microscopy.</a> J Surg Res. 121, 197-205 (2004).</li><li>Harder, Y., Contaldo, C., Klenk, J., Banic, A., Jakob, S. M., Erni, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preconditioning+with+monophosphoryl+lipid+A+improves+survival+of+critically+ischemic+tissue.">Preconditioning with monophosphoryl lipid A improves survival of critically ischemic tissue.</a> Anesth Analg. 100, 1786-1792 (2005).</li><li>Rezaeian, F., 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=Erythropoieton+protects+critically+perfused+flap+tissue.">Erythropoieton protects critically perfused flap tissue.</a> Ann Surg. 248, 919-929 (2008).</li><li>Harder, 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=Erythropoietin+reduces+necrosis+in+critically+ischemic+myocutaneous+tissue+by+protecting+nutritive+perfusion+in+a+dose-dependent+manner.">Erythropoietin reduces necrosis in critically ischemic myocutaneous tissue by protecting nutritive perfusion in a dose-dependent manner.</a> Surgery. 145, 10-1016 (2009).</li><li>Rezaeian, F., 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=Erythropoietin-induced+upregulation+of+endothelial+nitric+oxide+synthase+but+not+vascular+endothelial+growth+factor+prevents+musculocutaneous+tissue+from+ischemic+damage.">Erythropoietin-induced upregulation of endothelial nitric oxide synthase but not vascular endothelial growth factor prevents musculocutaneous tissue from ischemic damage.</a> Lab Invest. 90, 40-51 (2010).</li><li>Rezaeian, F., Ong, M. 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D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=N-acetylcysteine+attenuates+leukocytic+inflammation+and+microvascular+perfusion+failure+in+critically+ischemic+random+pattern+flaps.">N-acetylcysteine attenuates leukocytic inflammation and microvascular perfusion failure in critically ischemic random pattern flaps.</a> Microvasc Res. 82, 28-34 (2011).</li><li>Rezaeian, F., 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=Ghrelin+protects+musculocutaneous+tissue+from+ischemic+necrosis+by+improving+microvascular+perfusion.">Ghrelin protects musculocutaneous tissue from ischemic necrosis by improving microvascular perfusion.</a> Am J Physiol Heart Circ Physiol. 302, 603-610 (2012).</li><li>Rezaeian, F., 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=Long-term+preconditioning+with+Erythropoietin+reduces+ischemia-induced+skin+necrosis.">Long-term preconditioning with Erythropoietin reduces ischemia-induced skin necrosis.</a> Microcirculation. , (2013).</li><li>Harder, 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=Heat+shock+preconditioning+reduces+ischemic+tissue+necrosis+by+heat+shock+protein+(HSP)-32-mediated+improvement+of+the+microcirculation+rather+than+induction+of+ischemic+tolerance.">Heat shock preconditioning reduces ischemic tissue necrosis by heat shock protein (HSP)-32-mediated improvement of the microcirculation rather than induction of ischemic tolerance.</a> Ann Surg. 242, 869-878 (2005).</li><li>Tobalem, M., 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=Local+shockwave-induced+capillary+recruitment+improves+survival+of+musculocutaneous+flaps.">Local shockwave-induced capillary recruitment improves survival of musculocutaneous flaps.</a> J Surg Res. 184, 1196-1204 (2013).</li><li>Lindenblatt, N., Calcagni, M., Contaldo, C., Menger, M. 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In order to decrease ischemic complications and thereby improve the clinical outcome, more detailed knowledge of pathophysiologic processes in critically perfused flap tissue is required. The development of new animal models that mimic acute persistent ischemia is therefore mandatory. Accordingly, we were able to develop an easily reproducible and reliable model allowing for repetitive morphological, dynamic and functional real-time evaluation of various parameters of muscle and skin vasculature that can be correlated wi...

Coverage of exposed tendon, bone and implant material in reconstructive surgery relies on the use of flaps. A flap is a block of tissue that is transferred on its vascular pedicle that guarantees arterial inflow and venous outflow. Despite broad expertise and the availability of a variety of flaps to be transferred, ischemia-induced complications ranging from wound breakdown to total tissue loss are still encountered. Whereas conservative treatment and healing by secondary intention can be expected after minor tissue necrosis, significant flap necrosis usually requires surgical revision, including debridement, wound conditioning and secondary reconstruction. This increases morbidity, prolongs hospital stay and consequently leads to increased health care costs.
Flaps with an undefined pattern of vasculature or randomly perfused areas in the distal zone most remote from the arterial inflow are particularly prone to ischemic damage. Accordingly, numerous experimental and clinical studies have evaluated the development of necrosis in both, axial pattern flaps (defined blood supply) and random pattern flaps (undefined blood supply)1-3. The main findings are commonly based on macroscopic evaluation of the size of the necrotic area. In order to assess the causes and mechanisms of tissue necrosis more in detail, several studies focused on the analysis of microcirculation. Different techniques have been used to measure tissue perfusion, including the analysis of tissue oxygen tension using polarographic electrodes4-5, as well as the measurement of blood flow using laser Doppler flowmetry6-7, dye diffusion8, and microspheres9-10. These techniques, however, only allow for measuring indirect parameters of tissue perfusion and do not enable any morphological analysis of the microhemodynamic processes within an individual area of interest of a flap.
Sandison is known to be the first who has used a transparent chamber for prolonged in vivo studies, which he performed in rabbits11. In 1943 &#8212; approximately 20 years later &#8212; Algire was the first to adapt such a transparent chamber to be applicable in mice in order to study the behavior of micro-implants of tumor cells12. Due to the fact that mice are so-called loose skin animals and after some technical refinements over the following years, Lehr and co-workers were able to adapt such a dorsal skinfold chamber developing a smaller and lighter titanium chamber. This chamber enabled evaluation using intravital fluorescence microscopy, a technique that allows direct and repetitive visualization of a number of morphologic and microcirculatory features and their changes over time under different physiological and pathophysiological conditions, such as ischemia-reperfusion injury13.
In the investigation of perfusion of skin, muscle and bone flaps under normal and pathological conditions two trends occurred: First, the &#8220;acute&#8221; flap models that do not use the dorsal skinfold chamber such as the pedicled ear flap in the mouse14, the laterally based island skin flap in the hamster15 and the pedicled composite flap in the rat16. Second, the &#8220;chronic&#8221; flap model where the combination of a flap with a dorsal skinfold chamber permits repetitive microcirculatory analyses over several days with intravital fluorescence microscopy. It consists of a randomly perfused musculocutaneous flap that is integrated in the skinfold chamber of the mouse 17. Its width-to-length ratio was chosen that a situation of acute persistent ischemia consistently results in ~50% flap tissue necrosis 10 to 14 days after flap elevation. This reproducible extent of tissue necrosis allows further evaluation of both, protective (i.e., development of less necrosis) and detrimental factors (i.e., development of more necrosis) on flap pathophysiology. During the last years, several experimental publications demonstrating the effect of different pre-, peri- and post-conditioning procedures, including the administration of tissue-protective substances18-24 and the local application of physiologic stressors such as heat25 and shockwaves26, have emerged.
The quantitative analyses of necrosis, microvascular morphology and microcirculatory parameters can further be correlated to immunohistochemical analyses and protein assays. Different proteins and molecules including vascular endothelial growth factor (VEGF), nitric oxide synthases (NOS), nuclear factor kappa B (NF-&#954;B) and heat shock proteins (HSP-32: heme-oxygenase 1 (HO-1) and HSP-70) have been shown to play a role in tissue protection. Based on this chamber flap model, two modifications have been developed in order to analyze neovascularization and microcirculation during skin graft healing27 and angiogenic developments in a pedicled flap with axial pattern perfusion28. We present a reproducible and reliable model that includes an ischemically challenged musculocutaneous flap in the mouse skinfold chamber. This model allows visualization and quantification of the microcirculation and hemodynamics by intravital epi-fluorescence microscopy.

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			<td height="21" style="height:21px;width:319px;"><a name="RANGE!A1:D55">Name of Reagent/ Equipment</a></td>
			<td style="width:244px;">Company</td>
			<td style="width:119px;">Catalog Number</td>
			<td style="width:931px;">Comments/Description</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;">C57Bl/6 mice 6-8w 20-22g</td>
			<td style="width:244px;">Charles River</td>
			<td style="width:119px;"></td>
			<td></td>
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		<tr height="21">
			<td height="21" style="height:21px;width:319px;">depilation cream</td>
			<td style="width:244px;">Veet</td>
			<td style="width:119px;"></td>
			<td>any depilation cream</td>
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			<td height="21" style="height:21px;width:319px;">titanium chamber</td>
			<td style="width:244px;">Irola</td>
			<td align="right" style="width:119px;">160001</td>
			<td>Halteblech M</td>
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			<td height="21" style="height:21px;width:319px;">slotted cheese head screw</td>
			<td style="width:244px;">Screws and More</td>
			<td align="right">842210</td>
			<td>DIN84 M2x10</td>
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			<td height="21" style="height:21px;width:319px;">hexagon full nut</td>
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			<td align="right">93422</td>
			<td>DIN934 M2</td>
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			<td height="21" style="height:21px;width:319px;">snap ring</td>
			<td style="width:244px;">Schaefer-Peters</td>
			<td align="right">472212</td>
			<td>DIN472 J12x1,0</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:319px;">cover glass</td>
			<td style="width:244px;">Volab</td>
			<td style="width:119px;"></td>
			<td>custom-made cover glass 11,8mm in diameter</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;">fixing foam</td>
			<td style="width:244px;">tesamoll</td>
			<td>05559-100</td>
			<td>tesamoll Standard I-Profile</td>
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			<td height="21" style="height:21px;width:319px;">ketamine hydrochloride</td>
			<td style="width:244px;">Parke Davis</td>
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			<td>Ketavet&#174;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;">dihydroxylidinothiazine hydrochloride</td>
			<td style="width:244px;">Bayer</td>
			<td style="width:119px;"></td>
			<td>Rompun&#174;</td>
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			<td height="21" style="height:21px;width:319px;">Buprenorphin</td>
			<td style="width:244px;">Essex Pharma</td>
			<td style="width:119px;"></td>
			<td>Temgesic&#174;</td>
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			<td height="21" style="height:21px;width:319px;">Saline 0,9%</td>
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			<td height="21" style="height:21px;width:319px;">desinfection alcohol</td>
			<td style="width:244px;"></td>
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			<td></td>
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			<td height="21" style="height:21px;width:319px;">Vicryl 5-0</td>
			<td style="width:244px;">Ethicon</td>
			<td style="width:119px;">V 490 H</td>
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			<td height="21" style="height:21px;width:319px;">Ethilon 5-0</td>
			<td style="width:244px;">Ethicon</td>
			<td style="width:119px;">EH 7823 H</td>
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			<td height="21" style="height:21px;width:319px;">1ml syringes</td>
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			<td height="21" style="height:21px;width:319px;">surgical skin marker with flexible ruler</td>
			<td style="width:244px;">Purple surgical</td>
			<td>PS3151</td>
			<td>any surgical skin marker and flexible ruler</td>
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			<td height="21" style="height:21px;width:319px;">pointed scissors</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:319px;">Micro-Scissors</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:319px;">normal scissors</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:319px;">2 clamps</td>
			<td style="width:244px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;">fine anatomic forceps</td>
			<td style="width:244px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;">micro-forceps</td>
			<td style="width:244px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;"></td>
			<td style="width:244px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;">hex nuter driver</td>
			<td style="width:244px;">wiha</td>
			<td>1018</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;">screwdriver</td>
			<td style="width:244px;">wiha</td>
			<td style="width:119px;">685</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;">snap ring plier</td>
			<td style="width:244px;">Knipex</td>
			<td style="width:119px;">4411J1</td>
			<td>12-25mm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;">wire cutter</td>
			<td style="width:244px;">Knipex</td>
			<td style="width:119px;">70 02 160</td>
			<td>Wire cutter is used to cut screws short; 160mm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;"></td>
			<td style="width:244px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;">trans-illumination light</td>
			<td style="width:244px;">IKEA</td>
			<td>501.632.02</td>
			<td>LED light Jansj&#246;; any light&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;">magnification glasses</td>
			<td style="width:244px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;"></td>
			<td style="width:244px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;">intravital microscope</td>
			<td style="width:244px;">Zeiss</td>
			<td>490035-0001-000</td>
			<td>Scope.A1.Axiotech</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;">LED system</td>
			<td style="width:244px;">Zeiss</td>
			<td>423052-9501-000</td>
			<td>Colibri.2</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;">LED module 365nm</td>
			<td style="width:244px;">Zeiss</td>
			<td>423052-9011-000</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;">LED module 470nm</td>
			<td style="width:244px;">Zeiss</td>
			<td>423052-9052-000</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;">LED module 540-580nm</td>
			<td style="width:244px;">Zeiss</td>
			<td>423052-9121-000</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;">Filter set 62 62 HE BFP + GFP + HcRed</td>
			<td style="width:244px;">Zeiss</td>
			<td>489062-9901-000</td>
			<td>range 1: 350-390nm excitation wavelength split 395 / 402-448nm; range 2: 460-488nm, split 495nm / 500-557nm; range 3: 567-602nm, split 610nm / 615-infinite</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;">Filter set 20 Rhodamine</td>
			<td style="width:244px;">Zeiss</td>
			<td>485020-0000-000</td>
			<td>540-552nm, split 560, emission 575-640nm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;">2,5x objective NA=0,06</td>
			<td style="width:244px;">Zeiss</td>
			<td>421020-9900-000</td>
			<td>A-Plan 2,5x/0.06</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;">5x objective NA=0,16</td>
			<td style="width:244px;">Zeiss</td>
			<td>420330-9901-000</td>
			<td>EC Plan-Neofluar 5x/0.16 M27</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;">10x objetive NA=0,30</td>
			<td style="width:244px;">Zeiss</td>
			<td>420340-9901-000</td>
			<td>EC Plan-Neofluar 10x/0.30 M27</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;">20x objective NA=0.50</td>
			<td style="width:244px;">Zeiss</td>
			<td>420350-9900-000</td>
			<td>EC Plan-Neofluar 20x/0.50 M27</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;">50x objective NA=0,55</td>
			<td style="width:244px;">Zeiss</td>
			<td>422472-9960-000</td>
			<td>LD Epiplan-Neofluar 50x/0.55 DIC 27</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;"></td>
			<td style="width:244px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;">ZEN imaging software</td>
			<td style="width:244px;">Zeiss</td>
			<td style="width:119px;"></td>
			<td>ZenPro 2012</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;">CapImage</td>
			<td style="width:244px;">Dr. Zeintl</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;"></td>
			<td style="width:244px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;">Fluorescein isothiocyanate-dextran</td>
			<td style="width:244px;">Sigma-Aldrich</td>
			<td style="width:119px;">45946</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;">bisBenzimide H 33342 trihydrochloride</td>
			<td style="width:244px;">Sigma-Aldrich</td>
			<td style="width:119px;">B2261</td>
			<td>harmful if swallowed; causes severe skin burns and eye damage, may cause repiratory irritat</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;">Rhodamine 6G chloride</td>
			<td style="width:244px;">Invitrogen</td>
			<td style="width:119px;">R634</td>
			<td>harmful if swallowed; may cause genetic defects; may cause cancer; may damage fertility or the unborn child</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:319px;"></td>
			<td style="width:244px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:319px;">Pentobarbital</td>
			<td style="width:244px;">Merial</td>
			<td style="width:119px;"></td>
			<td>Narcoren&#174;</td>
		</tr>
	</tbody>
</table>

ischemic tissue injury in the dorsal skinfold chamber of the mouse: a skin flap model to investigate acute persistent ischemia

Despite profound expertise and advanced surgical techniques, ischemia-induced complications ranging from wound breakdown to extensive tissue necrosis are still occurring, particularly in reconstructive flap surgery. Multiple experimental flap models have been developed to analyze underlying causes and mechanisms and to investigate treatment strategies to prevent ischemic complications. The limiting factor of most models is the lacking possibility to directly and repetitively visualize microvascular architecture and hemodynamics. The goal of the protocol was to present a well-established mouse model affiliating these before mentioned lacking elements. Harder et al. have developed a model of a musculocutaneous flap with a random perfusion pattern that undergoes acute persistent ischemia and results in ~50% necrosis after 10 days if kept untreated. With the aid of intravital epi-fluorescence microscopy, this chamber model allows repetitive visualization of morphology and hemodynamics in different regions of interest over time. Associated processes such as apoptosis, inflammation, microvascular leakage and angiogenesis can be investigated and correlated to immunohistochemical and molecular protein assays. To date, the model has proven feasibility and reproducibility in several published experimental studies investigating the effect of pre-, peri- and postconditioning of ischemically challenged tissue.

Necrosis
The main endpoint of this model&#160;&#8212; tissue necrosis following flap elevation (i.e., induction of acute persistent ischemia) &#8212; is repeatedly measured and illustrated macroscopically as shown in Figure 3 over a period of 10 days. Final demarcation of flap necrosis usually occurs between day 5 and 7 after surgery and is characterized by a red fringe, i.e., zone of vasodilation and microvascular remodeling, developing betw...

Watch this Scientific Journal Video about Ischemic Tissue Injury in the Dorsal Skinfold Chamber of the Mouse: A Skin Flap Model to Investigate Acute Persistent Ischemia at JoVE.com

Ischemic Tissue Injury in the Dorsal Skinfold Chamber of the Mouse: A Skin Flap Model to Investigate Acute Persistent Ischemia

The window of the murine dorsal skinfold chamber presented visualizes a zone of acute persistent ischemia of a musculocutaneous flap. Intravital epi-fluorescence microscopy permits for direct and repetitive assessment of the microvasculature and quantification of hemodynamics. Morphologic and hemodynamic results can further be correlated with histological and molecular analyses.

Despite profound expertise and advanced surgical techniques, ischemia-induced complications ranging from wound breakdown to extensive tissue necrosis are ...

ischemic-tissue-injury-dorsal-skinfold-chamber-mouse-skin-flap-model

Research

JoVE Journal

Medicine

In situ Transverse Rectus Abdominis Myocutaneous Flap: A Rat Model of Myocutaneous Ischemia Reperfusion Injury

Free tissue transfer is the gold standard of reconstructive surgery to repair complex defects not amenable to local options or those requiring composite tissue. Ischemia reperfusion injury (IRI) is a known cause of partial free flap failure and has no effective treatment. Establishing a laboratory model of this injury can prove costly both financially as larger mammals are conventionally used and in the expertise required by the technical difficulty of these procedures typically requires employing an experienced microsurgeon. This publication and video demonstrate the effective use of a model of IRI in rats which does not require microsurgical expertise. This procedure is an in situ model of a transverse abdominis myocutaneous (TRAM) flap where atraumatic clamps are utilized to reproduce the ischemia-reperfusion injury associated with this surgery. A laser Doppler Imaging (LDI) scanner is employed to assess flap perfusion and the image processing software, Image J to assess percentage area skin survival as a primary outcome measure of injury.

In situ Transverse Rectus Abdominis Myocutaneous Flap: A Rat Model of Myocutaneous Ischemia Reperfusion Injury

Free tissue transfer is widely employed in reconstructive surgery to restore form and function following oncological resection and trauma. Preconditioning this tissue prior to surgery may improve outcome. This article describes an in situ transverse rectus abdominis myocutaneous flap (TRAM) in rats as a means for testing preconditioning strategies.

Free tissue transfer is the gold standard of reconstructive surgery to repair complex defects not amenable to local options or those requiring composite ...

Ischemia-reperfusion Model of Acute Kidney Injury and Post Injury Fibrosis in Mice

Ischemia-reperfusion induced acute kidney injury (IR-AKI) is widely used as a model of AKI in mice, but results are often quite variable with high, often unreported mortality rates that may confound analyses. Bilateral renal pedicle clamping is commonly used to induce IR-AKI, but differences between effective clamp pressures and/or renal responses to ischemia between kidneys often lead to more variable results. In addition, shorter clamp times are known to induce more variable tubular injury, and while mice undergoing bilateral injury with longer clamp times develop more consistent tubular injury, they often die within the first 3 days after injury due to severe renal insufficiency. To improve post-injury survival and obtain more consistent and predictable results, we have developed two models of unilateral ischemia-reperfusion injury followed by contralateral nephrectomy. Both surgeries are performed using a dorsal approach, reducing surgical stress resulting from ventral laparotomy, commonly used for mouse IR-AKI surgeries. For induction of moderate injury BALB/c mice undergo unilateral clamping of the renal pedicle for 26 min and also undergo simultaneous contralateral nephrectomy. Using this approach, 50-60% of mice develop moderate AKI 24 hr after injury but 90-100% of mice survive. To induce more severe AKI, BALB/c mice undergo renal pedicle clamping for 30 min followed by contralateral nephrectomy 8 days after injury. This allows functional assessment of renal recovery after injury with 90-100% survival. Early post-injury tubular damage as well as post injury fibrosis are highly consistent using this model.

We describe models of moderate and severe ischemia-reperfusion-induced kidney injury in which the mice undergo unilateral renal pedicle clamping followed by simultaneous or delayed contralateral nephrectomy, respectively. These models consistently give rise to renal dysfunction and post-injury fibrosis, but injury severity and survival are dependent on mouse background, age and surgical equipment.

Ischemia-reperfusion induced acute kidney injury (IR-AKI) is widely used as a model of AKI in mice, but results are often quite variable with high, often ...

A Murine Model of Myocardial Ischemia-reperfusion Injury through Ligation of the Left Anterior Descending Artery

Acute or chronic myocardial infarction (MI) are cardiovascular events resulting in high morbidity and mortality. Establishing the pathological mechanisms at work during MI and developing effective therapeutic approaches requires methodology to reproducibly simulate the clinical incidence and reflect the pathophysiological changes associated with MI. Here, we describe a surgical method to induce MI in mouse models that can be used for short-term ischemia-reperfusion (I/R) injury as well as permanent ligation. The major advantage of this method is to facilitate location of the left anterior descending artery (LAD) to allow for accurate ligation of this artery to induce ischemia in the left ventricle of the mouse heart. Accurate positioning of the ligature on the LAD increases reproducibility of infarct size and thus produces more reliable results. Greater precision in placement of the ligature will improve the standard surgical approaches to simulate MI in mice, thus reducing the number of experimental animals necessary for statistically relevant studies and improving our understanding of the mechanisms producing cardiac dysfunction following MI. This mouse model of MI is also useful for the preclinical testing of treatments targeting myocardial damage following MI.

We introduce a surgical method to induce experimental ischemia/reperfusion (I/R) injury to simulate myocardial infarction (MI) in mouse models that allows for more clarity in positioning of the ligation on the left anterior descending artery (LAD) to increase the reproducibility of MI experiments in mice.

Acute or chronic myocardial infarction (MI) are cardiovascular events resulting in high morbidity and mortality. Establishing the pathological mechanisms ...

Demonstration of the Rat Ischemic Skin Wound Model

The propensity for chronic wounds in humans increases with ageing, disease conditions such as diabetes and impaired cardiovascular function, and unrelieved pressure due to immobility. Animal models have been developed that attempt to mimic these conditions for the purpose of furthering our understanding of the complexity of chronic wounds. The model described herein is a rat ischemic skin flap model that permits a prolonged reduction of blood flow resulting in wounds that become ischemic and resemble a chronic wound phenotype (reduced vascularization, increased inflammation and delayed wound closure). It consists of a bipedicled dorsal flap with 2 ischemic wounds placed centrally and 2 non-ischemic wounds lateral to the flap as controls. A novel addition to this ischemic skin flap model is the placement of a silicone sheet beneath the flap that functions as a barrier and a splint to prevent revascularization and reduce contraction as the wounds heal. Despite the debate of using rats for wound healing studies due to their quite distinct anatomic and physiologic differences compared to humans (i.e., the presence of a panniculus carnosus muscle, short life-span, increased number of hair follicles, and their ability to heal infected wounds) the modifications employed in this model make it a valuable alternative to previously developed ischemic skin flap models.

The rat, due to its size, availability, and rather docile behavior, has been utilized as a research model for many years. The goal of this protocol is to utilize the rat as an ischemic skin wound healing model to provide valuable insight into the pathophysiology of chronic wounds.

The propensity for chronic wounds in humans increases with ageing, disease conditions such as diabetes and impaired cardiovascular function, and ...

Diffuse Optical Spectroscopy for the Quantitative Assessment of Acute Ionizing Radiation Induced Skin Toxicity Using a Mouse Model

Acute skin toxicities from ionizing radiation (IR) are a common side effect from therapeutic courses of external beam radiation therapy (RT) and negatively impact patient quality of life and long term survival. Advances in the understanding of the biological pathways associated with normal tissue toxicities have allowed for the development of interventional drugs, however, current response studies are limited by a lack of quantitative metrics for assessing the severity of skin reactions. Here we present a diffuse optical spectroscopic (DOS) approach that provides quantitative optical biomarkers of skin response to radiation. We describe the instrumentation design of the DOS system as well as the inversion algorithm for extracting the optical parameters. Finally, to demonstrate clinical utility, we present representative data from a pre-clinical mouse model of radiation induced erythema and compare the results with a commonly employed visual scoring. The described DOS method offers an objective, high through-put evaluation of skin toxicity via functional response that is translatable to the clinical setting.

We present a diffuse optical spectroscopic (DOS) approach that provides quantitative optical biomarkers of skin response to radiation. We describe DOS instrumentation design, optical parameters extraction algorithms and the animal handling procedures required to yield representative data from a pre-clinical mouse model of radiation induced erythema.

Acute skin toxicities from ionizing radiation (IR) are a common side effect from therapeutic courses of external beam radiation therapy (RT) and ...

Open Tracheostomy Gastric Acid Aspiration Murine Model of Acute Lung Injury Results in Maximal Acute Nonlethal Lung Injury

Acid pneumonitis is a major cause of sterile acute lung injury (ALI) in humans. Acid pneumonitis spans the clinical spectrum from asymptomatic to acute respiratory distress syndrome (ARDS), characterized by neutrophilic alveolitis, and injury to both alveolar epithelium and vascular endothelium. Clinically, ARDS is defined by acute onset of hypoxemia, bilateral patchy pulmonary infiltrates and non-cardiogenic pulmonary edema. Human studies have provided us with valuable information about the physiological and inflammatory changes in the lung caused by ARDS, which has led to various hypotheses about the underling mechanisms. Unfortunately, difficulties determining the etiology of ARDS, as well as a wide range of pathophysiology have resulted in a lack of critical information that could be useful in developing therapeutic strategies.
Translational animal models are valuable when their pathogenesis and pathophysiology accurately reproduce a concept proven in both in vitro and clinical settings. Although large animal models (e.g., sheep) share characteristics of the anatomy of human trachea-bronchial tree, murine models provide a host of other advantages including: low cost; short reproductive cycle lending itself to greater data acquisition; a well understood immunologic system; and a well characterized genome leading to the availability of a variety of gene deletion and transgenic strains. A robust model of low pH induced ARDS requires a murine ALI that targets mainly the alveolar epithelium, secondarily the vascular endothelium, as well as the small airways leading to the alveoli. Furthermore, a reproducible injury with wide differences between different injurious and non-injurious insults is important.
The murine gastric acid aspiration model presented here using hydrochloric acid employs an open tracheostomy and recreates a pathogenic scenario that reproduces the low pH pneumonitis injury in humans. Additionally, this model can be used to examine interaction of a low pH insult with other pulmonary injurious entities (e.g., food particles, pathogenic bacteria).

This protocol induces acute lung injury in a mouse that has close fidelity to the pathogenesis of acid pneumonitis observed in humans. We generate a maximal acute nonlethal low pH lung injury and account for differences in rodent-human anatomic respiratory structure using an open tracheostomy coupled with circumferential pressure release.

Acid pneumonitis is a major cause of sterile acute lung injury (ALI) in humans. Acid pneumonitis spans the clinical spectrum from asymptomatic to acute ...

Inducing Ischemia-reperfusion Injury in the Mouse Ear Skin for Intravital Multiphoton Imaging of Immune Responses

Ischemia-reperfusion injury (IRI) occurs when there is transient hypoxia due to the obstruction of blood flow (ischemia) followed by a subsequent re-oxygenation of the tissues (reperfusion). In the skin, ischemia-reperfusion (IR) is the main contributing factor to the pathophysiology of pressure ulcers. While the cascade of events leading up to the inflammatory response has been well studied, the spatial and temporal responses of the different subsets of immune cells to an IR injury are not well understood. Existing models of IR using the clamping technique on the skin flank are highly invasive and unsuitable for studying immune responses to injury, while similar non-invasive magnet clamping studies in the skin flank are less-than-ideal for intravital imaging studies. In this protocol, we describe a robust model of non-invasive IR developed on mouse ear skin, where we aim to visualize in real-time the cellular response of immune cells after reperfusion via multiphoton intravital imaging (MP-IVM).

This protocol describes the induction of an ischemia-reperfusion (IR) model on mouse ear skin using magnet clamping. Using a custom-built intravital imaging model, we study in vivo inflammatory responses post-reperfusion. The rationale behind the development of this technique is to extend the understanding of how leukocytes respond to skin IR injury.

Ischemia-reperfusion injury (IRI) occurs when there is transient hypoxia due to the obstruction of blood flow (ischemia) followed by a subsequent ...

A Model of Free Tissue Transfer: The Rat Epigastric Free Flap

Free tissue transfer has been increasingly used in clinical practice since the 1970s, allowing reconstruction of complex and otherwise untreatable defects resulting from tumor extirpation, trauma, infections, malformations or burns. Free flaps are particularly useful for reconstructing highly complex anatomical regions, like those of the head and neck, the hand, the foot and the perineum. Moreover, basic and translational research in the area of free tissue transfer is of great clinical potential. Notwithstanding, surgical trainees and researchers are frequently deterred from using microsurgical models of tissue transfer, due to lack of information regarding the technical aspects involved in the operative procedures. The aim of this paper is to present the steps required to transfer a fasciocutaneous epigastric free flap to the neck in the rat.
This flap is based on the superficial epigastric artery and vein, which originates from and drain into the femoral artery and vein, respectively. On average the caliber of the superficial epigastric vein is 0.6 to 0.8 mm, contrasting with the 0.3 to 0.5 mm of the superficial epigastric artery. Histologically, the flap is a composite block of tissues, containing skin (epidermis and dermis), a layer of fat tissue (panniculus adiposus), a layer of striated muscle (panniculus carnosus), and a layer of loose areolar tissue.
Succinctly, the epigastric flap is raised on its pedicle vessels that are then anastomosed to the external jugular vein and to the carotid artery on the ventral surface of the rat's neck. According to our experience, this model guarantees the complete survival of approximately 70 to 80% of epigastric flaps transferred to the neck region. The flap can be evaluated whenever needed by visual inspection. Hence, the authors believe this is a good experimental model for microsurgical research and training.

This paper describes the steps required to raise a fasciocutaneous epigastric free flap and transfer it to the neck in the rat.

Free tissue transfer has been increasingly used in clinical practice since the 1970s, allowing reconstruction of complex and otherwise untreatable defects ...

Modified Heterotopic Hindlimb Osteomyocutaneous Flap Model in the Rat for Translational Vascularized Composite Allotransplantation Research

Vascularized composite allotransplantation (VCA) is a relatively new field in the reconstructive surgery. Clinical achievements in human VCA include hand and face transplants and, more recently, abdominal wall, uterus, and urogenital transplants. Functional outcomes have exceeded initial expectations, and most recipients enjoy an improved quality of life. However, as clinical experience accumulates, chronic rejection and complications from the immunosuppression must be addressed. In many cases where grafts have failed, the causative pathology has been ischemic vasculopathy. <span style="font-size: 11pt; line-height: 115%; font-family: Arial, sans-serif; color: rgb(41, 43, 49); background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">The biological mechanisms of the acute and chronic rejection associated with VCA, especially ischemic vasculopathy, are important areas of research. However, due to the very small number of VCA patients, the evaluation of proposed mechanisms is better addressed in an experimental model. Multiple groups have used animal models to address some of the relevant unsolved questions in VCA rejection and vasculopathy. Several model designs involving a variety of species are described in the literature. Here we present a reproducible model of VCA heterotopic hindlimb osteomyocutaneous flap in the rat that can be utilized for translational VCA research. This model allows for the serial evaluation of the graft, including biopsies and different imaging modalities, while maintaining a low level of morbidity.

Vascularized composite allograft offers life-altering benefits to transplant recipients, but the biological causes of graft rejection and vasculopathy remain poorly understood. The rodent surgical model presented here offers a reproducible, clinically relevant model of transplantation, allowing researchers to evaluate rejection events and potential therapeutic strategies to prevent their occurrence.

Vascularized composite allotransplantation (VCA) is a relatively new field in the reconstructive surgery. Clinical achievements in human VCA include hand ...

Scratch Migration Assay and Dorsal Skinfold Chamber for In Vitro and In Vivo Analysis of Wound Healing

Impaired cutaneous wound healing is a major concern for patients suffering from diabetes and for elderly people, and there is a need for an effective treatment. Appropriate in vitro and in vivo approaches are essential for the identification of new target molecules for drug treatments to improve the skin wound healing process. We identified the &#946;3 subunit of voltage-gated calcium channels (Cav&#946;3) as a potential target molecule to influence the wound healing in two independent assays, i.e., the in vitro scratch migration assay and the in vivo dorsal skinfold chamber model. Primary mouse embryonic fibroblasts (MEFs) acutely isolated from wild-type (WT) and Cav&#946;3-deficient mice (Cav&#946;3 KO) or fibroblasts acutely isolated from WT mice treated with siRNA to down-regulate the expression of the Cacnb3 gene, encoding Cav&#946;3, were used. A scratch was applied on a confluent cell monolayer and the gap closure was followed by taking microscopic images at defined time points until complete repopulation of the gap by the migrating cells. These images were analyzed, and the cell migration rate was determined for each condition. In an in vivo assay, we implanted a dorsal skinfold chamber on WT and Cav&#946;3 KO mice, applied a defined circular wound of 2 mm diameter, covered the wound with a glass coverslip to protect it from infections and desiccation, and monitored the macroscopic wound closure over time. Wound closure was significantly faster in Cacnb3-gene-deficient mice. Because the results of the in vivo and the in vitro assays correlate well, the in vitro assay may be useful for the high-throughput screening before validating the in vitro hits by the in vivo wound healing model. What we have shown here for wild-type and Cav&#946;3-deficient mice or cells might also be applicable for specific molecules other than Cav&#946;3.

Here, we present a protocol for an in vitro scratch assay using primary fibroblasts and for an in vivo skin wound healing assay in mice. Both assays are straightforward methods to assess in vitro and in vivo wound healing.

Impaired cutaneous wound healing is a major concern for patients suffering from diabetes and for elderly people, and there is a need for an effective ...