This work was supported in part by the Army, Navy, NIH, Air Force, VA and Health Affairs to support the AFIRM II effort, under Award No. W81XWH-13-2-0054. The U.S. Army Medical Research Acquisition Activity, 820 Chandler Street, Fort Detrick, MD 21702-5014 is the awarding and administering acquisition office. Opinions, interpretations, conclusions, and recommendations are those of the author and are not necessarily endorsed by the Department of Defense.

All work involving live animals and animal tissue samples have been approved by the Massachusetts General Hospital Institutional Animal Care and Use Committee (IACUC).
1. Production of Harvesting Needles
<ol>
	<li>Setup of the production stage
	<ol>
		<li>Secure a female luer lock connector onto a post, and mount the post onto a rotation stage so that the luer lock is at the center of the stage (Figure 1A).</li>
		<li>Position this first rotation stage vertically, and mount it perpendicularly onto a second, horizontal rotation stage (Figure 1B).</li>
		<li>Mount the horizontal rotation stage onto a two-axis translation stage (Figure 1B).</li>
		<li>Fasten the combination onto a stable surface, such as an optical breadboard.</li>
		<li>Separately mount a rotary tool onto the same breadboard, with the tool positioned in parallel with the breadboard and at approximately the same height as the luer lock connector on the rotation/translation combination stage (Figure 1C).</li>
		<li>Install two cut-off wheels concentrically onto the rotary tool (a smaller, lower grit diamond cut-off wheel over a larger, higher grit stone cut-off wheel) (Figure 1D). 
		NOTE: About a 9 mm difference between the diameters of the two wheels is generally sufficient.</li>
		<li>Position an overhead light source with an adjustable arm over the rotary tool, with the light aimed at the cutting wheels.</li>
		<li>To enhance visualization, position a dissecting microscope over the production setup so that the eyepiece is focused on the cutting discs (Figure 1C). 
		&#8203;NOTE: Alternatively, users can wear magnifying eyewear.</li>
	</ol>
	</li>
	<li>Reshaping the needle tip
	<ol>
		<li>Wear protective eyewear and a surgical mask to prevent fine metal particles from entering the eyes or airways.</li>
		<li>Choose hypodermic needles of the appropriate gauge size, based on experimental requirements.</li>
		<li>Mark off the intended length on each harvesting needle. 
		NOTE: For harvesting from swine skin, 8 mm needles are typically sufficient; although, the length may vary based on experimental needs (e.g., thickness of target skin tissue, needle gauge size). Generally, a 19-gauge needle works well for swine skin.</li>
		<li>Lower the needle perpendicularly to the rotary tool with the power on, using the edge of the outer cutting disc to cut off the excess length of the needle, at the point marked in step 1.2.3.</li>
		<li>Connect the shortened, blunt needle to the female luer lock connector on the production stage.</li>
		<li>Adjust the horizontal rotation stage so that the needle is at a 12&#176; angle parallel to the cutting discs on the rotary tool (changing the angle will impact the force required for needle insertion).</li>
		<li>Turn on the overhead light and adjust its position while observing the needle under magnification, until the light is reflected off the midline (lengthwise) of the needle.</li>
		<li>Power on the rotary tool, then use the translation stage to advance the needle towards the inner (diamond) cutting disc (Figure 2A).</li>
		<li>Keep advancing the needle slowly against the cutting disc until the cutting disc reaches approximately the midline of the needle (as visualized by the overhead light&#39;s reflection along the midline).</li>
		<li>Slowly move the cut needle surface from the inner diamond wheel onto the outer stone wheel to finish the cut needle surface with a finer polish (Figure 2B).</li>
		<li>Retract the needle away from the cutting disc.</li>
		<li>Using the vertical rotation stage, rotate the needle 180&#176;.</li>
		<li>Repeat steps 1.2.9-1.2.10 to reshape the other side of the needle. 
		NOTE: The needle should now have two cutting tips of approximately equal length (Figure&#160;2C and 2D).</li>
		<li>Remove the needle from the production stage.</li>
		<li>Clean the inside bore with a metal wire that is slightly smaller than the needle&#39;s inner diameter.</li>
		<li>Using a sharp wooden stick (e.g., by snapping off the end of the small wooden stick on a cotton tip applicator), remove any burrs that may be still attached to the edges of the newly-formed needle. 
		NOTE: Harvesting needles can be electropolished and sterilized by autoclave if necessary.</li>
	</ol>
	</li>
</ol>
2. Skin Tissue Harvesting
<ol>
	<li>Use the harvesting needles to collect skin microcolumns from ex vivo tissue or live animals.</li>
	<li>For ex vivo skin tissue that is thin (especially from samples where the subcutaneous fat is missing or was trimmed away), hold the target tissue over the opening of a 50 mL centrifuge tube, or stack two pieces of tissue on top of each other, to avoid damaging the needle tips by hitting them against hard surfaces. 
	&#8203;NOTE: For in vivo harvesting from live animals, it is recommended that local lidocaine and epinephrine be administered by intradermal injection for analgesia and to reduce bleeding.</li>
	<li>Assemble the harvesting apparatus according to the amount of microcolumns needed, as described below.</li>
	<li>Low-medium volume option:
	<ol>
		<li>To harvest small to medium amounts of microcolumns, simply fill a standard syringe (10-20 mL syringes usually work well) with normal saline and connect it to a harvesting needle.</li>
		<li>Completely insert the harvesting needle into the donor skin, then retract it.</li>
		<li>Push on the piston of the syringe to flush saline through the harvesting needle and expel the microcolumn that is lodged in the needle bore.</li>
		<li>To speed up the harvesting process, repeat step 2.4.2 3 to 5 times before expelling the microcolumns in step 2.4.3. 
		NOTE: It is usually convenient to expel the microcolumns into a standard cell strainer to ease the subsequent collection of microcolumns.</li>
		<li>If needles become clogged, increase the pressure on the piston to expel the stuck tissue and remove the clog. If simply increasing pressure is insufficient, insert a metal wire through the needle tip opening to clear the clog in the needle bore.</li>
		<li>Keep the microcolumns submerged in saline or medium until use to prevent desiccation . 
		&#8203;NOTE: With an experienced operator, the method described above can be used to harvest microcolumns at a rate of approximately 1 microcolumn per second.</li>
	</ol>
	</li>
	<li>High volume option:
	<ol>
		<li>Create a simple suction-assisted device that can be constructed to facilitate collection of large amounts of microcolumns. 
		NOTE: The device consists of a harvesting needle, 20 mL syringe with luer lock nozzle, suction adapter typically used for liposuction (Figure 3A), and sterile suction canister.</li>
		<li>Remove the plunger from the 20 mL syringe.</li>
		<li>Attach the syringe to a suction adapter.</li>
		<li>Complete the assembly by attaching a harvesting needle to the syringe (Figure 3B).</li>
		<li>Use a piece of sterile suction tubing to connect the suction adapter to a sterile suction canister. Make sure the harvesting apparatus is connected to a canister input that allows fluid to flow into the canister unimpeded (which may require connection to a canister port that is marked for outflow rather than inflow).</li>
		<li>Connect the apparatus to a negative pressure source. 
		NOTE: The pressure required depends on needle diameter and length, as previously described8. For the apparatus described in this manuscript, the suction system found in typical operating rooms is generally sufficient.</li>
		<li>Connect a harvesting needle to the syringe.</li>
		<li>Harvest the microcolumns by inserting the harvesting needle into the skin. 
		NOTE: The microcolumns will be drawn into the syringe by suction, then flushed into the suction canister.</li>
		<li>Intermittently dip the harvesting needle into a container of sterile saline during the harvesting procedure to flush the system. 
		NOTE: This saline flush facilitates transport of the microcolumn and ensures they stay hydrated. Alternatively, an MFF luer adaptor can be connected to the luer lock of the syringe, and through a connection tubing, also to a hanging saline drip bag.</li>
		<li>Keep on hand a metal wire, or smaller gauge needle, that is slightly smaller than the harvesting needle&#39;s inner diameter. If the needle becomes clogged, it can be cleared by inserting the metal wire into the needle bore.</li>
		<li>When the desired amount of microcolumns have accumulated in the canister, disconnect the device from suction, then pour the contents of the suction canister out through a filter to collect the microcolumns.</li>
	</ol>
	</li>
	<li>After harvesting, apply a topical antibiotic ointment over the donor sites. 
	NOTE: Additional dressings are generally not required for donor sites.</li>
</ol>

<ol>
	<li>Sun, B. K., Siprashvili, Z., Khavari, P. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Advances+in+skin+grafting+and+treatment+of+cutaneous+wounds.">Advances in skin grafting and treatment of cutaneous wounds.</a> Science. 346 (6212), 941-945 (2014).</li><li>Singh, 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=Challenging+the+Conventional+Therapy:+Emerging+Skin+Graft+Techniques+for+Wound+Healing.">Challenging the Conventional Therapy: Emerging Skin Graft Techniques for Wound Healing.</a> Plastic and Reconstructive Surgery. 136 (4), 524-530 (2015).</li><li>Tam, J., 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=Fractional+Skin+Harvesting:+Autologous+Skin+Grafting+without+Donor-site+Morbidity.">Fractional Skin Harvesting: Autologous Skin Grafting without Donor-site Morbidity.</a> Plastic and Reconstructive Surgery. Global Open. 1 (6), 47 (2013).</li><li>Tam, J., 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=Reconstitution+of+full-thickness+skin+by+microcolumn+grafting.">Reconstitution of full-thickness skin by microcolumn grafting.</a> Journal of Tissue Engineering and Regenerative Medicine. 11 (10), 2796-2805 (2017).</li><li>Huang, 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=Regeneration+of+hair+and+other+skin+appendages:+A+microenvironment-centric+view.">Regeneration of hair and other skin appendages: A microenvironment-centric view.</a> Wound Repair and Regeneration. 24 (5), 759-766 (2016).</li><li>Fernandes, J. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Micro-mechanical+fractional+skin+rejuvenation.">Micro-mechanical fractional skin rejuvenation.</a> Plastic and Reconstructive Surgery. 131 (2), 216-223 (2013).</li><li>Rettinger, C. L., Fletcher, J. L., Carlsson, A. H., Chan, R. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Accelerated+epithelialization+and+improved+wound+healing+metrics+in+porcine+full-thickness+wounds+transplanted+with+full-thickness+skin+micrografts.">Accelerated epithelialization and improved wound healing metrics in porcine full-thickness wounds transplanted with full-thickness skin micrografts.</a> Wound Repair and Regeneration. 25 (5), 816-827 (2017).</li><li>Franco, W., 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=Fractional+skin+harvesting:+device+operational+principles+and+deployment+evaluation.">Fractional skin harvesting: device operational principles and deployment evaluation.</a> Journal of Medical Devices. 8 (4), 041005 (2014).</li><li>Rasmussen, C. A., 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=Chimeric+autologous/allogeneic+constructs+for+skin+regeneration.">Chimeric autologous/allogeneic constructs for skin regeneration.</a> Military Medicine. 179, 71-78 (2014).</li><li>Ter Horst, B., Chouhan, G., Moiemen, N. S., Grover, L. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Advances+in+keratinocyte+delivery+in+burn+wound+care.">Advances in keratinocyte delivery in burn wound care.</a> Advanced Drug Delivery Reviews. 123, 18-32 (2018).</li><li>Wong, V. W., Levi, B., Rajadas, J., Longaker, M. T., Gurtner, G. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stem+cell+niches+for+skin+regeneration.">Stem cell niches for skin regeneration.</a> International Journal of Biomaterials. 2012, 926059 (2012).</li><li>Manstein, D., Herron, G. S., Sink, R. K., Tanner, H., Anderson, R. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fractional+photothermolysis:+a+new+concept+for+cutaneous+remodeling+using+microscopic+patterns+of+thermal+injury.">Fractional photothermolysis: a new concept for cutaneous remodeling using microscopic patterns of thermal injury.</a> Lasers in Surgery and Medicine. 34 (5), 426-438 (2004).</li><li>Iriarte, C., Awosika, O., Rengifo-Pardo, M., Ehrlich, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Review+of+applications+of+microneedling+in+dermatology.">Review of applications of microneedling in dermatology.</a> Clinical, Cosmetic and Investigational Dermatology. 10, 289-298 (2017).</li><li>Anderson, R. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laser+treatment+of+traumatic+scars+with+an+emphasis+on+ablative+fractional+laser+resurfacing:+consensus+report.">Laser treatment of traumatic scars with an emphasis on ablative fractional laser resurfacing: consensus report.</a> Journal of the American Medical Association Dermatology. 150 (2), 187-193 (2014).</li><li>Hogan, S., Velez, M. W., Ibrahim, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microneedling:+a+new+approach+for+treating+textural+abnormalities+and+scars.">Microneedling: a new approach for treating textural abnormalities and scars.</a> Seminars in Cutaneous Medicine and Surgery. 36 (4), 155-163 (2017).</li><li>Manuskiatti, W., Fitzpatrick, R. E., Goldman, M. P. <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+effectiveness+and+side+effects+of+carbon+dioxide+laser+resurfacing+for+photoaged+facial+skin.">Long-term effectiveness and side effects of carbon dioxide laser resurfacing for photoaged facial skin.</a> Journal of the American Academy of Dermatology. 40 (3), 401-411 (1999).</li></ol>

The authors are co-inventors on patents relating to the technology described in this article, from which they have received licensing and royalty revenues through their institution, the Massachusetts General Hospital. J. Tam also consults for Medline Industries, Inc., which holds the commercial license for this technology.

The methods described here are intended to enable the collection of tissue microcolumns in sufficient quantities for in vivo large animal studies, using tools made from commercially available laboratory supplies. This apparatus has been used previously in harvesting tissue from excised human skin4,9 as well as live swine skin3. The specific parameters described are those that were found to be most suited for use in swine. It is ex...

Autologous skin grafting is the mainstay of wound repair, but it is limited by donor site scarcity and morbidity, leading to concerted efforts in recent decades to develop new therapeutic options to replace conventional skin grafting1,2. We recently developed an alternative method of harvesting skin to harness the benefits of full-thickness skin grafting while minimizing donor site morbidity. By collecting full-thickness skin in the form of small (~0.5 mm diameter) &#34;microcolumns&#34;, donor sites are able to heal rapidly and without scarring under normal circumstances (for potential exceptions, see the discussion section below)3. Microcolumns can be applied directly into wound beds to accelerate wound closure, reduce contraction3, and restore a diverse range of epidermal and dermal cell types and functional adnexal structures4, many of which are lacking in conventional split-thickness skin grafting or current bioengineered skin substitutes5. The ability of microcolumns to augment healing and of their donor sites to heal without scarring have both been independently validated by other research groups6,7.
We have previously developed a laboratory harvesting system to enable the collection of microcolumns at scale8; however, this system is composed of many customized components that are not widely available. Here, we describe in detail the process for producing harvesting needles, as well as simple collection systems, made from mostly off-the-shelf components, that can be used to achieve high-volume harvesting. The apparatus described in this manuscript is suitable for in vitro and animal work, but not for use in humans. A clinical device with FDA clearance for applying this technique in humans is commercially available but will not be discussed in detail here.

<table border="0" cellpadding="0" cellspacing="0" style="width:688px;" width="687">
	<tbody>
		<tr height="40">
			<td height="40" style="height:40px;width:216px;">Diamond wheel</td>
			<td style="width:135px;">Dremel</td>
			<td style="width:119px;">545</td>
			<td style="width:219px;"></td>
		</tr>
		<tr height="62">
			<td height="62" style="height:63px;width:216px;">Hypodermic needle (19G)</td>
			<td style="width:135px;">Fisher Scientific</td>
			<td style="width:119px;">14-840-98</td>
			<td style="width:219px;">Other needle sizes could be used, depending on experimental needs</td>
		</tr>
		<tr height="44">
			<td height="44" style="height:44px;width:216px;">Stome wheel</td>
			<td style="width:135px;">Dremel</td>
			<td style="width:119px;">540</td>
			<td style="width:219px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">Syringe (20mL with luer lock)</td>
			<td style="width:135px;">Fisher Scientific</td>
			<td style="width:119px;">22-124-967</td>
			<td style="width:219px;"></td>
		</tr>
		<tr height="52">
			<td height="52" style="height:52px;width:216px;">Suction adapter</td>
			<td style="width:135px;">Tulip Medical</td>
			<td style="width:119px;">PA20BD</td>
			<td style="width:219px;">Optional, for high volume harvesting</td>
		</tr>
		<tr height="70">
			<td height="70" style="height:71px;width:216px;">Suction canister</td>
			<td style="width:135px;">Fisher Scientific</td>
			<td style="width:119px;">19-898-212</td>
			<td style="width:219px;">Optional, for high volume harvesting. Sterilize before use.</td>
		</tr>
		<tr height="58">
			<td height="58" style="height:59px;width:216px;">Suction tubing</td>
			<td style="width:135px;">Medline</td>
			<td style="width:119px;">DYND50216H</td>
			<td style="width:219px;">Optional, for high volume harvesting</td>
		</tr>
	</tbody>
</table>

apparatus for harvesting tissue microcolumns

This manuscript describes the production process for a laboratory apparatus, made from off-the-shelf components, that can be used to collect microcolumns of full-thickness skin tissue. The small size of the microcolumns allows donor sites to heal quickly without causing donor site scarring, while harvesting full-thickness tissue enables the incorporation of all cellular and extracellular components of skin tissue, including those associated with deeper dermal regions and the adnexal skin structures, which have yet to be successfully reproduced using conventional tissue engineering techniques. The microcolumns can be applied directly into skin wounds to augment healing, or they can be used as the autologous cell/tissue source for other tissue engineering approaches. The harvesting needles are made by modifying standard hypodermic needles, and they can be used alone for harvesting small amounts of tissue or coupled with a simple suction-based collection system (also made from commonly available laboratory supplies) for high-volume harvesting to facilitate studies in large animal models.

The harvesting needles should be able to collect microcolumns of full-thickness skin tissue with approximately a 80-90% success rate, and each microcolumn should contain epidermis, dermis, and some subcutaneous fat (Figure 4). If the success rate of harvesting is low, or if it becomes difficult to insert a needle into tissue, then a new needle is likely needed. If the success rate for harvesting is consistently low, even with new needles, then the needles are...

Watch this Scientific Journal Video about Apparatus for Harvesting Tissue Microcolumns at JoVE.com

Apparatus for Harvesting Tissue Microcolumns

Here we describe a protocol for producing harvesting needles that can be used to collect full-thickness skin tissue without causing donor site scarring. The needles can be combined with a simple collection system to achieve high-volume harvesting.

This manuscript describes the production process for a laboratory apparatus, made from off-the-shelf components, that can be used to collect microcolumns ...

apparatus-for-harvesting-tissue-microcolumns

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5.9K Views.  Massachusetts General Hospital. Here we describe a protocol for producing harvesting needles that can be used to collect full-thickness skin tissue without causing donor site scarring. The needles can be combined with a simple collection system to achieve high-volume harvesting.

Video: Apparatus for Harvesting Tissue Microcolumns

Electrospinning Fundamentals: Optimizing Solution and Apparatus Parameters

Electrospun nanofiber scaffolds have been shown to accelerate the maturation, improve the growth, and direct the migration of cells in vitro. Electrospinning is a process in which a charged polymer jet is collected on a grounded collector; a rapidly rotating collector results in aligned nanofibers while stationary collectors result in randomly oriented fiber mats. The polymer jet is formed when an applied electrostatic charge overcomes the surface tension of the solution. There is a minimum concentration for a given polymer, termed the critical entanglement concentration, below which a stable jet cannot be achieved and no nanofibers will form - although nanoparticles may be achieved (electrospray). A stable jet has two domains, a streaming segment and a whipping segment. While the whipping jet is usually invisible to the naked eye, the streaming segment is often visible under appropriate lighting conditions. Observing the length, thickness, consistency and movement of the stream is useful to predict the alignment and morphology of the nanofibers being formed. A short, non-uniform, inconsistent, and/or oscillating stream is indicative of a variety of problems, including poor fiber alignment, beading, splattering, and curlicue or wavy patterns. The stream can be optimized by adjusting the composition of the solution and the configuration of the electrospinning apparatus, thus optimizing the alignment and morphology of the fibers being produced. In this protocol, we present a procedure for setting up a basic electrospinning apparatus, empirically approximating the critical entanglement concentration of a polymer solution and optimizing the electrospinning process. In addition, we discuss some common problems and troubleshooting techniques.

Electrospinning techniques can create a variety of nanofibrous scaffolds for tissue engineering or other applications. We describe here a procedure to optimize the parameters of the electrospinning solution and apparatus to obtain fibers with the desired morphology and alignment. Common problems and troubleshooting techniques are also presented.

Electrospun nanofiber scaffolds have been shown to accelerate the maturation, improve the growth, and direct the migration of cells in vitro. ...

Quantitatively Measuring In situ Flows using a Self-Contained Underwater Velocimetry Apparatus (SCUVA)

The ability to directly measure velocity fields in a fluid environment is necessary to provide empirical data for studies in fields as diverse as oceanography, ecology, biology, and fluid mechanics. Field measurements introduce practical challenges such as environmental conditions, animal availability, and the need for field-compatible measurement techniques. To avoid these challenges, scientists typically use controlled laboratory environments to study animal-fluid interactions. However, it is reasonable to question whether one can extrapolate natural behavior (i.e., that which occurs in the field) from laboratory measurements. Therefore, in situ quantitative flow measurements are needed to accurately describe animal swimming in their natural environment.
We designed a self-contained, portable device that operates independent of any connection to the surface, and can provide quantitative measurements of the flow field surrounding an animal. This apparatus, a self-contained underwater velocimetry apparatus (SCUVA), can be operated by a single scuba diver in depths up to 40 m. Due to the added complexity inherent of field conditions, additional considerations and preparation are required when compared to laboratory measurements. These considerations include, but are not limited to, operator motion, predicting position of swimming targets, available natural suspended particulate, and orientation of SCUVA relative to the flow of interest. The following protocol is intended to address these common field challenges and to maximize measurement success.

Quantitatively Measuring In situ Flows using a Self-Contained Underwater Velocimetry Apparatus SCUVA

This protocol provides instructions on how to use a self-contained underwater velocimetry apparatus (SCUVA), which is designed for quantification of in situ animal-generated flows. In addition, this protocol addresses challenges posed by field conditions, and includes operator motion, predicting position of animals, and orientation of SCUVA.

The ability to directly measure velocity fields in a fluid environment is necessary to provide empirical data for studies in fields as diverse as ...

Harvesting Murine Alveolar Macrophages and Evaluating Cellular Activation Induced by Polyanhydride Nanoparticles

Biodegradable nanoparticles have emerged as a versatile platform for the design and implementation of new intranasal vaccines against respiratory infectious diseases. Specifically, polyanhydride nanoparticles composed of the aliphatic sebacic acid (SA), the aromatic 1,6-bis(p-carboxyphenoxy)hexane (CPH), or the amphiphilic 1,8-bis(p-carboxyphenoxy)-3,6-dioxaoctane (CPTEG) display unique bulk and surface erosion kinetics1,2 and can be exploited to slowly release functional biomolecules (e.g., protein antigens, immunoglobulins, etc.) in vivo3,4,5. These nanoparticles also possess intrinsic adjuvant activity, making them an excellent choice for a vaccine delivery platform6,7,8.
	In order to elucidate the mechanisms governing the activation of innate immunity following intranasal mucosal vaccination, one must evaluate the molecular and cellular responses of the antigen presenting cells (APCs) responsible for initiating immune responses. Dendritic cells are the principal APCs found in conducting airways, while alveolar macrophages (AM&#632;) predominate in the lung parenchyma9,10,11. AM&#632; are highly efficient in clearing the lungs of microbial pathogens and cell debris12,13. In addition, this cell type plays a valuable role in the transport of microbial antigens to the draining lymph nodes, which is an important first step in the initiation of an adaptive immune response9. AM&#632; also express elevated levels of innate pattern recognition and scavenger receptors, secrete pro-inflammatory mediators, and prime na&iuml;ve T cells12,14. A relatively pure population of AM&#632; (e.g., greater than 80%) can easily be obtained via lung lavage for study in the laboratory. Resident AM&#632; harvested from immune competent animals provide a representative phenotype of the macrophages that will encounter the particle-based vaccine in vivo. Herein, we describe the protocols used to harvest and culture AM&#632; from mice and examine the activation phenotype of the macrophages following treatment with polyanhydride nanoparticles in vitro.

Herein, we describe protocols for harvesting murine alveolar macrophages, which are resident innate immune cells in the lung, and examining their activation in response to co-culture with polyanhydride nanoparticles.

Biodegradable nanoparticles have emerged as a  versatile platform for the design and implementation of new intranasal vaccines  against respiratory ...

Non-contact, Label-free Monitoring of Cells and Extracellular Matrix using Raman Spectroscopy

Non-destructive, non-contact and label-free technologies to monitor cell and tissue cultures are needed in the field of biomedical research.1-5 However, currently available routine methods require processing steps and alter sample integrity. Raman spectroscopy is a fast method that enables the measurement of biological samples without the need for further processing steps. This laser-based technology detects the inelastic scattering of monochromatic light.6 As every chemical vibration is assigned to a specific Raman band (wavenumber in cm-1), each biological sample features a typical spectral pattern due to their inherent biochemical composition.7-9 Within Raman spectra, the peak intensities correlate with the amount of the present molecular bonds.1 Similarities and differences of the spectral data sets can be detected by employing a multivariate analysis (e.g. principal component analysis (PCA)).10
Here, we perform Raman spectroscopy of living cells and native tissues. Cells are either seeded on glass bottom dishes or kept in suspension under normal cell culture conditions (37 &deg;C, 5% CO2) before measurement. Native tissues are dissected and stored in phosphate buffered saline (PBS) at 4 &deg;C prior measurements. Depending on our experimental set up, we then either focused on the cell nucleus or extracellular matrix (ECM) proteins such as elastin and collagen. For all studies, a minimum of 30 cells or 30 random points of interest within the ECM are measured. Data processing steps included background subtraction and normalization.

Raman spectroscopy is a suitable technique for the non-contact, label-free analysis of living cells, tissue-engineered constructs and native tissues. Source-specific spectral fingerprints can be generated and analyzed using multivariate analysis.

Non-destructive, non-contact and label-free technologies to monitor cell and tissue cultures are needed in the field of biomedical research.1-5 However, ...

Capillary Force Lithography for Cardiac Tissue Engineering

Cardiovascular disease remains the leading cause of death worldwide1. Cardiac tissue engineering holds much promise to deliver groundbreaking medical discoveries with the aims of developing functional tissues for cardiac regeneration as well as in vitro screening assays. However, the ability to create high-fidelity models of heart tissue has proven difficult. The heart&#8217;s extracellular matrix (ECM) is a complex structure consisting of both biochemical and biomechanical signals ranging from the micro- to the nanometer scale2. Local mechanical loading conditions and cell-ECM interactions have recently been recognized as vital components in cardiac tissue engineering3-5.
A large portion of the cardiac ECM is composed of aligned collagen fibers with nano-scale diameters that significantly influences tissue architecture and electromechanical coupling2. Unfortunately, few methods have been able to mimic the organization of ECM fibers down to the nanometer scale. Recent advancements in nanofabrication techniques, however, have enabled the design and fabrication of scalable scaffolds that mimic the in vivo structural and substrate stiffness cues of the ECM in the heart6-9.
Here we present the development of two reproducible, cost-effective, and scalable nanopatterning processes for the functional alignment of cardiac cells using the biocompatible polymer poly(lactide-co-glycolide) (PLGA)8 and a polyurethane (PU) based polymer. These anisotropically nanofabricated substrata (ANFS) mimic the underlying ECM of well-organized, aligned tissues and can be used to investigate the role of nanotopography on cell morphology and function10-14.
Using a nanopatterned (NP) silicon master as a template, a polyurethane acrylate (PUA) mold is fabricated. This PUA mold is then used to pattern the PU or PLGA hydrogel via UV-assisted or solvent-mediated capillary force lithography (CFL), respectively15,16. Briefly, PU or PLGA pre-polymer is drop dispensed onto a glass coverslip and the PUA mold is placed on top. For UV-assisted CFL, the PU is then exposed to UV radiation (&#955; = 250-400 nm) for curing. For solvent-mediated CFL, the PLGA is embossed using heat (120 &#176;C) and pressure (100 kPa). After curing, the PUA mold is peeled off, leaving behind an ANFS for cell culture. Primary cells, such as neonatal rat ventricular myocytes, as well as human pluripotent stem cell-derived cardiomyocytes, can be maintained on the ANFS2.

In this protocol, we demonstrate the fabrication of biomimetic cardiac cell culture substrata made from two distinct polymeric materials using capillary force lithography. The described methods provide a scalable, cost-effective technique to engineer the structure and function of macroscopic cardiac tissues for in vitro and in vivo applications.

Cardiovascular disease remains the leading cause of death worldwide1. Cardiac tissue engineering holds much promise to deliver groundbreaking medical ...

Self-reporting Scaffolds for 3-Dimensional Cell Culture

Culturing cells in 3D on appropriate scaffolds is thought to better mimic the in vivo microenvironment and increase cell-cell interactions. The resulting 3D cellular construct can often be more relevant to studying the molecular events and cell-cell interactions than similar experiments studied in 2D. To create effective 3D cultures with high cell viability throughout the scaffold the culture conditions such as oxygen and pH need to be carefully controlled as gradients in analyte concentration can exist throughout the 3D construct. Here we describe the methods of preparing biocompatible pH responsive sol-gel nanosensors and their incorporation into poly(lactic-co-glycolic acid) (PLGA) electrospun scaffolds along with their subsequent preparation for the culture of mammalian cells. The pH responsive scaffolds can be used as tools to determine microenvironmental pH within a 3D cellular construct. Furthermore, we detail the delivery of pH responsive nanosensors to the intracellular environment of mammalian cells whose growth was supported by electrospun PLGA scaffolds. The cytoplasmic location of the pH responsive nanosensors can be utilized to monitor intracellular pH (pHi) during ongoing experimentation.

Biocompatible pH responsive sol-gel nanosensors can be incorporated into poly(lactic-co-glycolic acid) (PLGA) electrospun scaffolds. The produced self-reporting scaffolds can be used for in&#160;situ monitoring of microenvironmental conditions whilst culturing cells upon the scaffold. This is beneficial as the 3D cellular construct can be monitored in real-time without disturbing the experiment.

Culturing cells in 3D on appropriate scaffolds is thought to better mimic the in vivo microenvironment and increase cell-cell interactions. The resulting ...

Hydrogel Nanoparticle Harvesting of Plasma or Urine for Detecting Low Abundance Proteins

Novel biomarker discovery plays a crucial role in providing more sensitive and specific disease detection. Unfortunately many low-abundance biomarkers that exist in biological fluids cannot be easily detected with mass spectrometry or immunoassays because they are present in very low concentration, are labile, and are often masked by high-abundance proteins such as albumin or immunoglobulin. Bait containing poly(N-isopropylacrylamide) (NIPAm) based nanoparticles are able to overcome these physiological barriers. In one step they are able to capture, concentrate and preserve biomarkers from body fluids. Low-molecular weight analytes enter the core of the nanoparticle and are captured by different organic chemical dyes, which act as high affinity protein baits. The nanoparticles are able to concentrate the proteins of interest by several orders of magnitude. This concentration factor is sufficient to increase the protein level such that the proteins are within the detection limit of current mass spectrometers, western blotting, and immunoassays. Nanoparticles can be incubated with a plethora of biological fluids and they are able to greatly enrich the concentration of low-molecular weight proteins and peptides while excluding albumin and other high-molecular weight proteins. Our data show that a 10,000 fold amplification in the concentration of a particular analyte can be achieved, enabling mass spectrometry and immunoassays to detect previously undetectable biomarkers.

Several pathological biomarkers cannot be easily detected by current techniques because of their low concentration in biological fluids, the presence of degrading enzymes, and large amounts of high molecular weight proteins. Chemically functionalized hydrogel nanoparticles can harvest, preserve and concentrate low abundance proteins enabling the detection of previously undetectable biomarkers.

Novel biomarker discovery plays a crucial role in providing more sensitive and specific disease detection. Unfortunately many low-abundance biomarkers ...

Custom-designed Laser-based Heating Apparatus for Triggered Release of Cisplatin from Thermosensitive Liposomes with Magnetic Resonance Image Guidance

Liposomes have been employed as drug delivery systems to target solid tumors through exploitation of the enhanced permeability and retention (EPR) effect resulting in significant reductions in systemic toxicity. Nonetheless, insufficient release of encapsulated drug from liposomes has limited their clinical efficacy. Temperature-sensitive liposomes have been engineered to provide site-specific release of drug in order to overcome the problem of limited tumor drug bioavailability. Our lab has designed and developed a heat-activated thermosensitive liposome formulation of cisplatin (CDDP), known as HTLC, to provide triggered release of CDDP at solid tumors. Heat-activated delivery in vivo was achieved in murine models using a custom-built laser-based heating apparatus that provides a conformal heating pattern at the tumor site as confirmed by MR thermometry (MRT). A fiber optic temperature monitoring device was used to measure the temperature in real-time during the entire heating period with online adjustment of heat delivery by alternating the laser power. Drug delivery was optimized under magnetic resonance (MR) image guidance by co-encapsulation of an MR contrast agent (i.e.,&#160;gadoteridol) along with CDDP into the thermosensitive liposomes as a means to validate the heating protocol and to assess tumor accumulation. The heating protocol consisted of a preheating period of 5 min prior to administration of HTLC and 20 min heating post-injection. This heating protocol resulted in effective release of the encapsulated agents with the highest MR signal change observed in the heated tumor in comparison to the unheated tumor and muscle. This study demonstrated the successful application of the laser-based heating apparatus for preclinical thermosensitive liposome development and the importance of MR-guided validation of the heating protocol for optimization of drug delivery.

AN MRI-compatible&#160;custom-designed laser-based heating apparatus has been developed to provide local heating of subcutaneous tumors in order to activate release of agents from thermosensitive liposomes specifically at the tumor region.

Liposomes have been employed as drug delivery systems to target solid tumors through exploitation of the enhanced permeability and retention (EPR) effect ...

Sandwich-like Microenvironments to Harness Cell/Material Interactions

Cell culture has been traditionally carried out on bi-dimensional (2D) substrates where cells adhere using ventral receptors to the biomaterial surface. However in vivo, most of the cells are completely surrounded by the extracellular matrix (ECM), resulting in a three-dimensional (3D) distribution of receptors. This may trigger differences in the outside-in signaling pathways and thus in cell behavior.
This article shows that stimulating the dorsal receptors of cells already adhered to a 2D substrate by overlaying a film of a new material (a sandwich-like culture) triggers important changes with respect to standard 2D cultures. Furthermore, the simultaneous excitation of ventral and dorsal receptors shifts cell behavior closer to that found in 3D environments. Additionally, due to the nature of the system, a sandwich-like culture is a versatile tool that allows the study of different parameters in cell/material interactions, e.g., topography, stiffness and different protein coatings at both the ventral and dorsal sides. Finally, since sandwich-like cultures are based on 2D substrates, several analysis procedures already developed for standard 2D cultures can be used normally, overcoming more complex procedures needed for 3D systems.

The following protocol describes the procedure to assemble sandwich-like cultures to be used as an intermediate stage between bi-dimensional (2D) and three-dimensional (3D) cellular environments. The engineered systems can have applications in microscopy, biomechanics, biochemistry and cell biology assays.

Cell culture has been traditionally carried out on bi-dimensional (2D) substrates where cells adhere using ventral receptors to the biomaterial surface. ...

A Microfluidic Platform for High-throughput Single-cell Isolation and Culture

Studying the heterogeneity of single cells is crucial for many biological questions, but is technically difficult. Thus, there is a need for a simple, yet high-throughput, method to perform single-cell culture experiments. Here, we report a microfluidic chip-based strategy for high-efficiency single-cell isolation (~77%) and demonstrate its capability of performing long-term single-cell culture (up to 7 d) and cellular heterogeneity analysis using clonogenic assay. These applications were demonstrated with KT98 mouse neural stem cells, and A549 and MDA-MB-435 human cancer cells. High single-cell isolation efficiency and long-term culture capability are achieved by using different sizes of microwells on the top and bottom of the microfluidic channel. The small microwell array is designed for precisely isolating single-cells, and the large microwell array is used for single-cell clonal culture in the microfluidic chip. This microfluidic platform constitutes an attractive approach for single-cell culture applications, due to its flexibility of adjustable cell culture spaces for different culture strategies, without decreasing isolation efficiency.

Here, we present a protocol for isolating and culturing single cells with a microfluidic platform, which utilizes a new microwell design concept to allow for high-efficiency single cell isolation and long-term clonal culture.

Studying the heterogeneity of single cells is crucial for many biological questions, but is technically difficult. Thus, there is a need for a simple, yet ...