The authors have no acknowledgements.

An exempt approval (3002-13) to carry out research using de-identified tissue samples pursuant to the Department of Health and Human Services regulations, 45 CFR 46.101(b)(4) was granted. Full thickness skin is received from elective surgery. In this article, the tissue source is 66-year-old Caucasian female breast.
1. Preparation of Elastomer Coated Coverslips
<ol>
	<li>In a 20 mL glass vial, mix 0.107 g of Sylgard 184 curing agent with 5.893 g base. The total mixture mass is 6 g with a bas...

<ol>
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K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effects+of+barrier+disruption+and+moisturization+on+the+dynamic+drying+mechanics+of+human+stratum+corneum.">The effects of barrier disruption and moisturization on the dynamic drying mechanics of human stratum corneum.</a> J. Mech. Behav. Biomed. Mater. 49 (13), 80-89 (2015).</li><li>Levi, K., Weber, R. J., Do, J. Q., Dauskardt, R. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Drying+stress+and+damage+processes+in+human+stratum+corneum.">Drying stress and damage processes in human stratum corneum.</a> Int. J. Cosmet. Sci. 32 (4), 276-293 (2010).</li><li>Levi, 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=Effect+of+glycerin+on+drying+stresses+in+human+stratum+corneum.">Effect of glycerin on drying stresses in human stratum corneum.</a> J. Dermatol. Sci. 61, 129-131 (2011).</li><li>Fluhr, J. W., Darlenski, R., Surber, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glycerol+and+the+skin:+holistic+approach+to+its+origin+and+functions.">Glycerol and the skin: holistic approach to its origin and functions.</a> Br. J. Dermatol. 159 (1), 23-34 (2008).</li><li>German, G. 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=Heterogeneous+drying+stresses+in+stratum+corneum.">Heterogeneous drying stresses in stratum corneum.</a> Biophys. J. 102 (11), 2424-2432 (2012).</li><li>Willert, C. E., Gharib, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Digital+particle+image+velocimetry.">Digital particle image velocimetry.</a> Exp. Fluids. 10 (4), 181-193 (1991).</li><li>Mertz, A. 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=Scaling+of+traction+forces+with+the+size+of+cohesive+cell+colonies.">Scaling of traction forces with the size of cohesive cell colonies.</a> Phys. Rev. Lett. 108 (19), 1-5 (2012).</li><li>Banerjee, S., Marchetti, M. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Substrate+rigidity+deforms+and+polarizes+active+gels.">Substrate rigidity deforms and polarizes active gels.</a> Euro Phys. Lett. 96 (2), 28003 (2011).</li><li>Edwards, C. M., Schwarz, U. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Force+localization+in+contracting+cell+layers.">Force localization in contracting cell layers.</a> Phys. Rev. Lett. 107 (12), 128101 (2011).</li><li>Cesa, 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=Micropatterned+silicone+elastomer+substrates+for+high+resolution+analysis+of+cellular+force+patterns.">Micropatterned silicone elastomer substrates for high resolution analysis of cellular force patterns.</a> Rev. Sci. Instrum. 78 (3), 34301 (2007).</li><li>Wu, K. S., Van Osdol, W. W., Dauskardt, R. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanical+And+Microstructural+Properties+Of+Stratum+Corneum.">Mechanical And Microstructural Properties Of Stratum Corneum.</a> Mater. Res. Soc. 724, 27-33 (2002).</li><li>Yuan, Y., Verma, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measuring+microelastic+properties+of+stratum+corneum.">Measuring microelastic properties of stratum corneum.</a> Colloids Surf. B. 48 (1), 6-12 (2006).</li><li>Christensen, M. S., Hargens, C. W., Nacht, S., Gans, E. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Viscoelastic+properties+of+intact+human+skin:+instrumentation,+hydration+effects,+and+the+contribution+of+the+stratum+corneum.">Viscoelastic properties of intact human skin: instrumentation, hydration effects, and the contribution of the stratum corneum.</a> J Invest. Dermatol. 69 (3), (1977).</li><li>Pailler-Mattei, C., Bec, S., Zahouani, H. <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+measurements+of+the+elastic+mechanical+properties+of+human+skin+by+indentation+tests.">In vivo measurements of the elastic mechanical properties of human skin by indentation tests.</a> Med. Eng.Phys. 30 (5), 599-606 (2008).</li></ol>

In this article, we describe a technique that can be used to measure the dynamic drying behavior and mechanical properties of human SC. Previous studies have demonstrated that this technique can be used to quantify the effects of environmental conditions and chemical products commonly used in cosmetic cleansers and moisturizers on the dynamic drying behavior of SC7,8. There are a number of key steps in the protocol. Firstly, SC swells notably with water content; ...

The outer most layer of the epidermis, or stratum corneum (SC) consists of cohesive corneocyte cells surrounded by a lipid rich matrix1,2. The composition and structural integrity of SC is essential for maintaining correct barrier functionality3, which prevents invasion from microorganisms and resists both mechanical forces and excessive water loss4. The capacity of personal care products to maintain or degrade skin barrier function is of great interest to skin healthcare and the cosmetic industry5. The daily application of personal care products is known to alter the mechanical properties of the SC6,7,8. For example, surfactants contained in cosmetic cleansers can cause significant increases in the elastic modulus and a build-up of drying stresses in SC, increasing the tissue&#39;s propensity to crack7,9. Glycerol contained in nearly all cosmetic moisturizers can soften SC and decrease the build-up of drying stresses8,10,11, reducing the likelihood of tissue rupture.
The method detailed in this article is capable of quantifying the dynamic drying behavior and mechanical properties of SC drying in controlled environments7,8. Previously, this technique has been demonstrated to be capable of elucidating the effect of different cosmetic products on changes in the dynamic drying behavior and mechanical properties of SC tissue. This is achieved by quantifying drying-induced shrinkage of human SC tissue adhered to a soft elastomer substrate, fitting drying displacements with a simple contractility model, and then extracting the elastic modulus and drying stress from the fitted profile. When testing of multiple SC samples is required, this method offers a more rapid alternative to uniaxial tensometry, utilizes significantly less tissue and provides more physiologically relevant drying by preventing evaporation from the sample underside.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Silicone elastomer base</td>
			<td>Dow-Corning</td>
			<td>1064291</td>
		</tr>
		<tr>
			<td>Silicone elastomer Curing Agent</td>
			<td>Dow-Corning</td>
			<td>1015311</td>
		</tr>
		<tr>
			<td>FluoSpheres Carboxylate 0.1 &#181;m yellow green fluorescent 505/515&#160;</td>
			<td>Thermo Fisher</td>
			<td>F8803</td>
		</tr>
		<tr>
			<td>FluoSpheres Carboxylate 1 &#181;m yellow green fluorescent 505/515&#160;</td>
			<td>Thermo Fisher</td>
			<td>F8823</td>
		</tr>
		<tr>
			<td>FluoSpheres Carboxylate 1 &#181;m nile red fluorescent 535/575&#160;</td>
			<td>Thermo Fisher</td>
			<td>F8819</td>
		</tr>
		<tr>
			<td>Trypsin from porcine pancreas</td>
			<td>Sigma-Aldrich</td>
			<td>T6567</td>
		</tr>
		<tr>
			<td>Trypsin inhibitor type II-s</td>
			<td>Sigma-Aldrich</td>
			<td>T9128</td>
		</tr>
		<tr>
			<td>(3-aminopropyl)triethoxysilane</td>
			<td>Sigma-Aldrich</td>
			<td>440140</td>
		</tr>
		<tr>
			<td>Sodium tetraborate</td>
			<td>Sigma-Aldrich</td>
			<td>221732</td>
		</tr>
		<tr>
			<td>Boric acid</td>
			<td>Sigma-Aldrich</td>
			<td>B0294</td>
		</tr>
		<tr>
			<td>Phosphate buffered saline</td>
			<td>Sigma-Aldrich</td>
			<td>P7059</td>
		</tr>
		<tr>
			<td>N-(3-Dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride&#160;</td>
			<td>Sigma-Aldrich</td>
			<td>E7750</td>
		</tr>
		<tr>
			<td>Vortexer mixer</td>
			<td>VWR</td>
			<td>58816-123</td>
		</tr>
		<tr>
			<td>6mm diameter hole punch</td>
			<td>Sigma-Aldrich</td>
			<td>Z708860</td>
		</tr>
		<tr>
			<td>SOLA 6-LCR-SB&#160;</td>
			<td>Lummencor light engine</td>
			<td>No.3526</td>
		</tr>
		<tr>
			<td>Cfi Plan Achro Uw 1x Objective</td>
			<td>Nikon Plan UW</td>
			<td>MRL00012</td>
		</tr>
		<tr>
			<td>CFI Plan Fluor 40x Oil Objective 1.3 na - 0.20mm wd</td>
			<td>Nikon Plan Fluor</td>
			<td>MRH01401</td>
		</tr>
		<tr>
			<td>Nikon Eclipse Ti-U inverted microscope&#160;</td>
			<td>Nikon</td>
			<td>MEA53200</td>
		</tr>
		<tr>
			<td>Clara-E Camera</td>
			<td>Andor</td>
			<td>DR-328G-C02-SIL</td>
		</tr>
		<tr>
			<td>Remote Focus Attachment E-RFA Ergo Design</td>
			<td>Nikon</td>
			<td>99888</td>
		</tr>
		<tr>
			<td>Ti-S-E Motorized Stage</td>
			<td>Nikon</td>
			<td>MEC56110</td>
		</tr>
	</tbody>
</table>

measuring and modeling contractile drying in human stratum corneum

Stratum corneum (SC) is the most superficial skin layer. Its contact with the external environment means that this tissue layer is subjected to both cleansing agents and daily variations in ambient moisture; both of which can alter the water content of the tissue. Reductions in water content from severe barrier dysfunction or low humidity environments can alter SC stiffness and cause a build-up of drying stresses. In extreme conditions, these factors can cause mechanical rupture of the tissue. We have established a high throughput method of quantifying dynamic changes in the mechanical properties of SC upon drying. This technique can be employed to quantify changes in the drying behavior and mechanical properties of SC with cosmetic cleanser and moisturizer treatments. This is achieved by measuring dynamic variations in spatially resolved in-plane drying displacements of circular tissue samples adhered to an elastomer substrate. In-plane radial displacements acquired during drying are azimuthally averaged and fitted with a profile based on a linear elastic contractility model. Dynamic changes in drying stress and SC elastic modulus can then be extracted from the fitted model profiles.

Figure 1(a) shows a representative fluorescent image of an SC sample coated with fluorescent beads (section 3). The corresponding transmitted light image of the sample is shown in Figure 1(b) overlaid with a quiver plot of spatially resolved drying displacements that form after 16 h drying at 25% R.H. Due to the circular symmetry of the samples, these displacements can be azimuthally averaged. Figure 1(c) shows radial (ur, soli...

Watch this Scientific Journal Video about Measuring and Modeling Contractile Drying in Human Stratum Corneum at JoVE.com

Measuring and Modeling Contractile Drying in Human Stratum Corneum

This article describes a method of quantifying the dynamic drying behavior and mechanical properties of stratum corneum by measuring spatially resolved in-plane drying displacements of circular tissue samples adhered to an elastomer substrate. This technique can be used to measure how different chemical treatments alter drying and tissue mechanical properties.

Stratum corneum (SC) is the most superficial skin layer. Its contact with the external environment means that this tissue layer is subjected to both ...

The overall goal of this method is to quantify the dynamic mechanical stiffness and build up of drying stresses in ex vivo samples of human stratum corneum, after different chemical treatments. This method can help answer key questions in the biomechanics and cosmetic science fields, such as how the composition of of the stratum corneum or treatment of the skin tissue with a personal care products can influence, it's mechanical properties and dynamic drying behavior. The main advantage of this technique is that it offers a more rapid alternative to other mechanical assessment methods, requires significantly less skin tissue and provides more physiologically relevant drying by preventing evaporation from the sample underside.To prepare elastomer coated coverslips, first make Sylgard 184 curing agent with base solids at a base to curing agent ratio of 55 to one, until it is homogenous. Six grams in total are needed. Next, de-gas the solution.Then use the solution to coat the coverslips on a spin coater. Using a wide bore pipette, drop one milliliter of the mixture centrally on a coverslip. Then spin coat the coverslip at 2, 000 rpm for 60 seconds.Make five or six coated coverslips in this manner. To cure the coverslips, keep them in a 60 degree Celsius oven for 12 hours. The next day, measure the elastomer films thicknesess.Use a razor blade to lift one edge of the elastomer film off the coverslip. Then use an indelible marker to mark the top side of the elastomer film and to mark the treated coverslip beneath. Now, using an inverted microscope, measure the Z height between the focal planes of the marks to measure the films thicknesses.Follow standard procedures to prepare the SC tissue. To make samples, take six millimeter diameter punches from the SC.On the samples, place a mark at the center of the outmost face using an indelible marker. Next, deposit fluorescent marker beads onto the SC surface by floating the samples in 15 milliliters of water, containing about 90 microliters of bead concentrate.Use gentle agitation for 30 minutes and adjust the bead concentration as needed. After the treatment, immerse each sample in water to mount it onto the elastomer. Position a coated coverslip at a shallow angle, 15 to 30 degrees under the SC with the elastomer towards the bottom side of the SC.Then lift the coverslip from the water with the SC attached above, thus smoothly laminating the SC sample without wrinkles or trapped air.Next, dry the mounted samples at ambient conditions for about an hour. Once dried, transfer the samples to a hermetically sealed chamber containing a dish of water. Allow the samples to equilibrate to the humidity for 24 hours.The next day, mount a sample to a perfusion chamber for a prolonged imaging session. Place the perfusion chamber over the substrate and seal the edges of the perfusion chamber to the elastomer using vacuum grease. Then record fluorescent and transmitted light images with a field of view large enough to capture the full SC sample.Over the next 16 hours, take an image every 10 minutes. In a chemical fume hood, load a small plastic cap with one milliliter of silane. Transfer the cap into a sealed container with one elastomer lined coverslip, not in direct contact.Allow them to incubate at room temperature for five hours. While waiting, prepare 20 milliliters of bead solution according to the text protocol and then pour it into a 10 centimeter dish. After five hours, slowly place the silanated substrates elastomer side down, into the bead solution.Load two substrates into each dish and let the substrates react with the beads for 45 minutes. Later, using tweezers, remove the substrates and rinse them in distilled water to remove the unbound beads. Then dry them under a gentle stream of compressed air and store them in a sealed, opaque box.Using the previously described technique, transfer the SC samples onto a treated substrate in a water bath. Immediately after mounting the SC, apply a five microliter drop of un-diluted fluorescent marker bead solution onto it. Then allow the SC to dry for 60 minutes.Now, measure the SC thickness using the microscope with a 40x subjective lens in a perfusion chamber. Measure the thickness of SC over time, using a remote focus accessory to record the difference in Z height between the two bead layers. One layer is at the SC substrate interface and the other is on top of the SC.Using the described techniques, an SC sample was prepared and coated with fluorescent beads.After 16 hours of drying, at 25%relative humidity, displacements were measured. Due to the circular symmetry of the samples, these displacements were azimuthally averaged. Throughout drying, azimuthal displacements remain small.Radial displacement profiles however, increased monotonically from the center to the edge and grew in magnitude until an equilibrium was reached. Profiles recorded at 30 minute intervals show the time evolution of in-plane displacements. The average SC thickness decreased during drying, primarily over the first two hours.The drying dynamic was then analyzed by fitting the displacement profiles to a linear, elastic contractility model using a minimum least squares approach. From the model, the contractual drying stress was extracted, as well as the elastic modulus. Both parameters increased rapidly over the first two hours of drying.While attempting this procedure, it is important to remember to adhere the samples onto the substrate completely. Following this procedure, other methods like lipid staining can be performed in order to answer additional questions such as how particular cosmetic treatments alter tissue lipid composition.

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6.5K ビュー.  Binghamton University. The overall goal of this method is to quantify the dynamic mechanical stiffness and build up of drying stresses in ex vivo samples of human stratum corneum, after different chemical treatments. This method can help answer key questions in the biomechanics and cosmetic science fields, such as how the composition of of the stratum corneum or treatment of the skin tissue with a personal care products can influence, it's mechanical properties and dynamic drying behavior. The main advantage of thi...

ビデオ: Measuring and Modeling Contractile Drying in Human Stratum Corneum

This article describes a method of quantifying the dynamic drying behavior and mechanical properties of stratum corneum by measuring spatially resolved in-plane drying displacements of circular tissue samples adhered to an elastomer substrate. This technique can be used to measure how different chemical treatments alter drying and tissue mechanical...

resolving water, proteins, and lipids from in vivo confocal raman spectra of stratum corneum through a chemometric approach

Resolving Water, Proteins, and Lipids from In Vivo Confocal Raman Spectra of Stratum Corneum through a Chemometric Approach

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utilization of microscale silicon cantilevers to assess cellular contractile function in vitro

Utilization of Microscale Silicon Cantilevers to Assess Cellular Contractile Function In Vitro

This protocol describes the use of microscale silicon cantilevers as pliable culture surfaces for measuring the contractility of muscle cells in vitro. Cellular contraction causes cantilever bending, which can be measured, recorded, and converted into readouts of force, providing a non-invasive and scalable system for measuring contractile function in...

Utilization of Microscale Silicon Cantilevers to Assess Cellular Contractile Function In Vitro

formulations for freeze-drying of bacteria and their influence on cell survival

Formulations for Freeze-drying of Bacteria and Their Influence on Cell Survival

Freeze-drying is often an easy and convenient way to obtain dry products of viable bacterial cells. An issue of the process is cell survival. We detail here a procedure to investigate how cell survival during freeze-drying is influenced by the properties of the formulation...

intrauterine telemetry to measure mouse contractile pressure in vivo

Intrauterine Telemetry to Measure Mouse Contractile Pressure In Vivo

This manuscript provides a protocol for implanting telemeters in the mouse for the purpose of measuring intrauterine pressures during pregnancy.

Intrauterine Telemetry to Measure Mouse Contractile Pressure In Vivo

Measuring Left Ventricular Pressure in Late Embryonic and Neonatal Mice

Blood pressure increases significantly during embryonic and postnatal development in vertebrate animals. In the mouse, blood flow is first detectable around embryonic day (E) 8.51. Systolic left ventricular (LV) pressure is 2 mmHg at E9.5 and 11 mmHg at E14.52. At these mid-embryonic stages, the LV is clearly visible through the chest wall for invasive pressure measurements because the ribs and skin are not fully developed. Between E14.5 and birth (approximately E21) imaging methods must be used to view the LV. After birth, mean arterial pressure increases from 30 - 70 mmHg from postnatal day (P) 2 - 353. Beyond P20, arterial pressure can be measured with solid-state catheters (i.e. Millar or Scisense). Before P20, these catheters are too big for developing mouse arteries and arterial pressure must be measured with custom pulled plastic catheters attached to fluid-filled pressure transducers3 or glass micropipettes attached to servo null pressure transducers4.
Our recent work has shown that the greatest increase in blood pressure occurs during the late embryonic to early postnatal period in mice5-7. This large increase in blood pressure may influence smooth muscle cell (SMC) phenotype in developing arteries and trigger important mechanotransduction events. In human disease, where the mechanical properties of developing arteries are compromised by defects in extracellular matrix proteins (i.e. Marfan's Syndrome8 and Supravalvular Aortic Stenosis9) the rapid changes in blood pressure during this period may contribute to disease phenotype and severity through alterations in mechanotransduction signals. Therefore, it is important to be able to measure blood pressure changes during late embryonic and neonatal periods in mouse models of human disease.
We describe a method for measuring LV pressure in late embryonic (E18) and early postnatal (P1 - 20) mice. A needle attached to a fluid-filled pressure transducer is inserted into the LV under ultrasound guidance. Care is taken to maintain normal cardiac function during the experimental protocol, especially for the embryonic mice. Representative data are presented and limitations of the protocol are discussed.

Measuring left ventricular pressure (LV) in embryonic and neonatal mice is described. Pressure is measured by inserting a needle connected to a fluid-filled transducer into the LV under ultrasound guidance. Care must be taken to maintain normal cardiac function during the experimental protocol.

Blood pressure increases significantly during embryonic and postnatal development in vertebrate animals. In the mouse, blood flow is first detectable ...

CometChip: A High-throughput 96-Well Platform for Measuring DNA Damage in Microarrayed Human Cells

DNA damaging agents can promote aging, disease and cancer and they are ubiquitous in the environment and produced within human cells as normal cellular metabolites. Ironically, at high doses DNA damaging agents are also used to treat cancer. The ability to quantify DNA damage responses is thus critical in the public health, pharmaceutical and clinical domains. Here, we describe a novel platform that exploits microfabrication techniques to pattern cells in a fixed microarray. The &#8216;CometChip&#8217; is based upon the well-established single cell gel electrophoresis assay (a.k.a. the comet assay), which estimates the level of DNA damage by evaluating the extent of DNA migration through a matrix in an electrical field. The type of damage measured by this assay includes abasic sites, crosslinks, and strand breaks. Instead of being randomly dispersed in agarose in the traditional assay, cells are captured into an agarose microwell array by gravity. The platform also expands from the size of a standard microscope slide to a 96-well format, enabling parallel processing. Here we describe the protocols of using the chip to evaluate DNA damage caused by known genotoxic agents and the cellular repair response followed after exposure. Through the integration of biological and engineering principles, this method potentiates robust and sensitive measurements of DNA damage in human cells and provides the necessary throughput for genotoxicity testing, drug development, epidemiological studies and clinical assays.

We describe here a platform that allows comet assay detection of DNA damage with unprecedented throughput. The device patterns mammalian cells into a microarray and enables parallel processing of 96 samples. The approach facilitates analysis of base level DNA damage, exposure-induced DNA damage and DNA repair kinetics.

DNA damaging agents can promote aging, disease and cancer and they are ubiquitous in the environment and produced within human cells as normal cellular ...

Quantification of Global Diastolic Function by Kinematic Modeling-based Analysis of Transmitral Flow via the Parametrized Diastolic Filling Formalism

Quantitative cardiac function assessment remains a challenge for physiologists and clinicians.&#160;Although historically invasive methods have comprised the only means available, the development of noninvasive imaging modalities (echocardiography, MRI, CT) having high temporal and spatial resolution provide a new window for quantitative diastolic function assessment. Echocardiography is the agreed upon standard for diastolic function assessment, but indexes in current clinical use merely utilize selected features of chamber dimension (M-mode) or blood/tissue motion (Doppler) waveforms without incorporating the physiologic causal determinants of the motion itself.&#160;The recognition that all left ventricles (LV) initiate filling by serving as mechanical suction pumps allows global diastolic function to be assessed based on laws of motion that apply to all chambers. What differentiates one heart from another are the parameters of the equation of motion that governs filling. Accordingly, development of the Parametrized Diastolic Filling (PDF) formalism&#160;has shown that the entire range of clinically observed early transmitral flow (Doppler E-wave) patterns are extremely well fit by the laws of damped oscillatory motion.&#160;This permits analysis of individual E-waves in accordance with a causal mechanism (recoil-initiated suction) that yields three (numerically) unique lumped parameters whose physiologic analogues are chamber stiffness (k), viscoelasticity/relaxation (c), and load (xo).&#160;The recording of transmitral flow (Doppler E-waves) is standard practice in clinical cardiology and, therefore, the echocardiographic recording method is only briefly reviewed. Our focus is on determination of the PDF parameters from routinely recorded E-wave data.&#160;As the highlighted results indicate, once the PDF parameters have been obtained from a suitable number of load varying E-waves, the investigator is free to use the parameters or construct indexes from the parameters (such as stored energy 1/2kxo2, maximum A-V pressure gradient kxo, load independent index of diastolic function, etc.) and select the aspect of physiology or pathophysiology to be quantified.

Accurate, causality-based quantification of global diastolic function has been achieved by kinematic modeling-based analysis of transmitral flow via the Parametrized Diastolic Filling (PDF) formalism. PDF generates unique stiffness, relaxation,&#160;and load parameters and elucidates &#39;new&#39; physiology while providing sensitive and specific indexes of dysfunction.

Quantitative cardiac function assessment remains a challenge for physiologists and clinicians.&#160;Although historically invasive methods have comprised ...

The development of more predictive and biologically relevant in vitro assays is predicated on the advancement of versatile cell culture systems which facilitate the functional assessment of the seeded cells. To that end, microscale cantilever technology offers a platform with which to measure the contractile functionality of a range of cell types, including skeletal, cardiac, and smooth muscle cells, through assessment of contraction induced substrate bending. Application of multiplexed cantilever arrays provides the means to develop moderate to high-throughput protocols for assessing drug efficacy and toxicity, disease phenotype and progression, as well as neuromuscular and other cell-cell interactions. This manuscript provides the details for fabricating reliable cantilever arrays for this purpose, and the methods required to successfully culture cells on these surfaces. Further description is provided on the steps necessary to perform functional analysis of contractile cell types maintained on such arrays using a novel laser and photo-detector system. The representative data provided highlights the precision and reproducible nature of the analysis of contractile function possible using this system, as well as the wide range of studies to which such technology can be applied. Successful widespread adoption of this system could provide investigators with the means to perform rapid, low cost functional studies in vitro, leading to more accurate predictions of tissue performance, disease development and response to novel therapeutic treatment.

This protocol describes the use of microscale silicon cantilevers as pliable culture surfaces for measuring the contractility of muscle cells in vitro. Cellular contraction causes cantilever bending, which can be measured, recorded, and converted into readouts of force, providing a non-invasive and scalable system for measuring contractile function in vitro.

The development of more predictive and biologically relevant in vitro assays is predicated on the advancement of versatile cell culture systems which ...

Production, Characterization and Potential Uses of a 3D Tissue-engineered Human Esophageal Mucosal Model

The incidence of both esophageal adenocarcinoma and its precursor, Barrett&#8217;s Metaplasia, are rising rapidly in the western world. Furthermore esophageal adenocarcinoma generally has a poor prognosis, with little improvement in survival rates in recent years. These are difficult conditions to study and there has been a lack of suitable experimental platforms to investigate disorders of the esophageal mucosa.
A model of the human esophageal mucosa has been developed in the MacNeil laboratory which, unlike conventional 2D cell culture systems, recapitulates the cell-cell and cell-matrix interactions present in vivo and produces a mature, stratified epithelium similar to that of the normal human esophagus. Briefly, the model utilizes non-transformed normal primary human esophageal fibroblasts and epithelial cells grown within a porcine-derived acellular esophageal scaffold. Immunohistochemical characterization of this model by CK4, CK14, Ki67 and involucrin staining demonstrates appropriate recapitulation of the histology of the normal human esophageal mucosa.
This model provides a robust, biologically relevant experimental model of the human esophageal mucosa. It can easily be manipulated to investigate a number of research questions including the effectiveness of pharmacological agents and the impact of exposure to environmental factors such as alcohol, toxins, high temperature or gastro-esophageal refluxate components. The model also facilitates extended culture periods not achievable with conventional 2D cell culture, enabling, inter alia, the study of the impact of repeated exposure of a mature epithelium to the agent of interest for up to 20 days. Furthermore, a variety of cell lines, such as those derived from esophageal tumors or Barrett&#8217;s Metaplasia, can be incorporated into the model to investigate processes such as tumor invasion and drug responsiveness in a more biologically relevant environment.

This manuscript describes the production, characterization and potential uses of a tissue engineered 3D esophageal construct prepared from normal primary human esophageal fibroblast and squamous epithelial cells seeded within a de-cellularized porcine scaffold. The results demonstrate the formation of a mature stratified epithelium similar to the normal human esophagus.

The incidence of both esophageal adenocarcinoma and its precursor, Barrett&#8217;s Metaplasia, are rising rapidly in the western world. Furthermore ...

Methods for the Self-integration of Megamolecular Biopolymers on the Drying Air-LC Interface

Living organisms that use water are always prone to drying in the environment. Their activities are driven by biopolymer-based micro- and macro-structures, as seen in the cases of moving water in vascular bundles and moisturizing water in skin layers. In this study, we developed a method for assessing the effect of aqueous liquid crystalline (LC) solutions composed of biopolymers on drying. As LC biopolymers have megamolecular weight, we chose to study polysaccharides, cytoskeletal proteins, and DNA. The observation of biopolymer solutions during drying under polarized light reveals milliscale self-integration starting from the unstable air-LC interface. The dynamics of the aqueous LC biopolymer solutions can be monitored by evaporating water from a one-side-open cell. By analyzing the images taken using cross-polarized light, it is possible to recognize the spatio-temporal changes in the orientational order parameter. This method can be useful for the characterization of not only artificial materials in various fields, but also natural living tissues. We believe that it will provide an evaluation method for soft materials in the biomedical and environmental fields.

A method for the drying-induced self-integration of megamolecular biopolymers on the air-liquid crystalline interface is provided here. This methodology will be useful not only for understanding the macroscopic potentials of biopolymers, but also as an evaluation method for soft materials in biomedical and environmental fields.

Living organisms that use water are always prone to drying in the environment. Their activities are driven by biopolymer-based micro- and ...

Microhoneycomb Monoliths Prepared by the Unidirectional Freeze-drying of Cellulose Nanofiber Based Sols: Method and Extensions

Monolithic honeycomb structures have been attractive to multidisciplinary fields due to their high strength-to-weight ratio. Particularly, microhoneycomb monoliths (MHMs) with micrometer-scale channels are expected as efficient platforms for reactions and separations because of their large surface areas. Up to now, MHMs have been prepared by a unidirectional freeze-drying (UDF) method only from very limited precursors. Herein, we report a protocol from which a series of MHMs consisting of different components can be obtained. Recently, we found that cellulose nanofibers function as a distinct structure-directing agent towards the formation of MHMs through the UDF process. By mixing the cellulose nanofibers with water soluble substances which do not yield MHMs, a variety of composite MHMs can be prepared. This significantly enriches the chemical constitution of MHMs towards versatile applications.

Here, we present a general protocol to prepare a variety of microhoneycomb monoliths (MHMs) in which fluid can pass through with an extremely low pressure drop. MHMs obtained are expected to be used as filters, catalyst supports, flow-type electrodes, sensors and scaffolds for biomaterials.

Monolithic honeycomb structures have been attractive to multidisciplinary fields due to their high strength-to-weight ratio. Particularly, microhoneycomb ...

Measuring Global Cellular Matrix Metalloproteinase and Metabolic Activity in 3D Hydrogels

Three-dimensional (3D) cell culture systems often more closely recapitulate in vivo cellular responses and functions than traditional two-dimensional (2D) culture systems. However, measurement of cell function in 3D culture is often more challenging. Many biological assays require retrieval of cellular material which can be difficult in 3D cultures. One way to address this challenge is to develop new materials that enable measurement of cell function within the material. Here, a method is presented for measurement of cellular matrix metalloproteinase (MMP) activity in 3D hydrogels in a 96-well format. In this system, a poly(ethylene glycol) (PEG) hydrogel is functionalized with a fluorogenic MMP cleavable sensor. Cellular MMP activity is proportional to fluorescence intensity and can be measured with a standard microplate reader. Miniaturization of this assay to a 96-well format reduced the time required for experimental set up by 50% and reagent usage by 80% per condition as compared to the previous 24-well version of the assay. This assay is also compatible with other measurements of cellular function. For example, a metabolic activity assay is demonstrated here, which can be conducted simultaneously with MMP activity measurements within the same hydrogel. The assay is demonstrated with human melanoma cells encapsulated across a range of cell seeding densities to determine the appropriate encapsulation density for the working range of the assay. After 24 h of cell encapsulation, MMP and metabolic activity readouts were proportional to cell seeding density. While the assay is demonstrated here with one fluorogenic degradable substrate, the assay and methodology could be adapted for a wide variety of hydrogel systems and other fluorescent sensors. Such an assay provides a practical, efficient and easily accessible 3D culturing platform for a wide variety of applications.

Here, a protocol is presented for encapsulating and culturing cells in poly(ethylene glycol) (PEG) hydrogels functionalized with a fluorogenic matrix metalloproteinase (MMP)-degradable peptide. Cellular MMP and metabolic activity are measured directly from the hydrogel cultures using a standard microplate reader.

Three-dimensional (3D) cell culture systems often more closely recapitulate in vivo cellular responses and functions than traditional two-dimensional (2D) ...

Electric and Magnetic Field Devices for Stimulation of Biological Tissues

Electric fields (EFs) and magnetic fields (MFs) have been widely used by tissue engineering to improve cell dynamics such as proliferation, migration, differentiation, morphology, and molecular synthesis. However, variables such stimuli strength and stimulation times need to be considered when stimulating either cells, tissues or scaffolds. Given that EFs and MFs vary according to cellular response, it remains unclear how to build devices that generate adequate biophysical stimuli to stimulate biological samples. In fact, there is a lack of evidence regarding the calculation and distribution when biophysical stimuli are applied. This protocol is focused on the design and manufacture of devices to generate EFs and MFs and implementation of a computational methodology to predict biophysical stimuli distribution inside and outside of biological samples. The EF device was composed of two parallel stainless-steel electrodes located at the top and bottom of biological cultures. Electrodes were connected to an oscillator to generate voltages (50, 100, 150 and 200 Vp-p) at 60 kHz. The MF device was composed of a coil, which was energized with a transformer to generate a current (1 A) and voltage (6 V) at 60 Hz. A polymethyl methacrylate support was built to locate the biological cultures in the middle of the coil. The computational simulation elucidated the homogeneous distribution of EFs and MFs inside and outside of biological tissues. This computational model is a promising tool that can modify parameters such as voltages, frequencies, tissue morphologies, well plate types, electrodes and coil size to estimate the EFs and MFs to achieve a cellular response.

This protocol describes the step-by-step process to build both electrical and magnetic stimulators used to stimulate biological tissues. The protocol includes a guideline to simulate computationally electric and magnetic fields and manufacture of stimulator devices.

Electric fields (EFs) and magnetic fields (MFs) have been widely used by tissue engineering to improve cell dynamics such as proliferation, migration, ...

Measuring 3D In-vivo Shoulder Kinematics using Biplanar Videoradiography

The shoulder is one of the human body's most complex joint systems, with motion occurring through the coordinated actions of four individual joints, multiple ligaments, and approximately 20 muscles. Unfortunately, shoulder pathologies (e.g., rotator cuff tears, joint dislocations, arthritis) are common, resulting in substantial pain, disability, and decreased quality of life. The specific etiology for many of these pathologic conditions is not fully understood, but it is generally accepted that shoulder pathology is often associated with altered joint motion. Unfortunately, measuring shoulder motion with the necessary level of accuracy to investigate motion-based hypotheses is not trivial. However, radiographic-based motion measurement techniques have provided the advancement necessary to investigate motion-based hypotheses and provide a mechanistic understanding of shoulder function. Thus, the purpose of this article is to describe the approaches for measuring shoulder motion using a custom biplanar videoradiography system. The specific objectives of this article are to describe the protocols to acquire biplanar videoradiographic images of the shoulder complex, acquire CT scans, develop 3D bone models, locate anatomical landmarks, track the position and orientation of the humerus, scapula, and torso from the biplanar radiographic images, and calculate the kinematic outcome measures. In addition, the article will describe special considerations unique to the shoulder when measuring joint kinematics using this approach.

Biplane videoradiography can quantify shoulder kinematics with a high degree of accuracy. The protocol described herein was specifically designed to track the scapula, humerus, and the ribs during planar humeral elevation, and outlines the procedures for data collection, processing, and analysis. Unique considerations for data collection are also described.

The shoulder is one of the human body's most complex joint systems, with motion occurring through the coordinated actions of four individual joints, ...