We thank Kristin Johnson for the graphic work.

All protocols involving animals are presented to and approved by the Institutional Animal Care and Use Committee at Children&#39;s Hospital Boston and are conducted in accordance with the recommendations of the Association for Assessment and Accreditation of Laboratory Animal Care (AAALAC). Be sure to use sterile instrumentation and aseptic techniqure while performing the procedure.&#160;
1. Preparation of Pellets
<ol>
	<li>Weigh out 10 mg of sucralfate and 60 mg of hydron with the sterile unbent spatula.&#160; Place in separate microcentrifuge tubes.</li>
	<li>Place a 1 cm square piece of mesh into a sterile 10 cm dish.&#160; Invert so mesh rests on shallow lid.&#160; Set aside.</li>
	<li>Add 500 &#956;l of ethanol to the hydron and vortex for at least 10 min.</li>
	<li>Add the appropriate amount of growth factor (standard: 20 &#956;g for bFGF, 50 &#956;g for VEGF) to the sucralfate and vortex briefly.&#160; Store growth factor in a -80 &#176;C freezer at a concentration of 1 mg/ml.&#160; Liquid volumes added should be a minimum of 20 &#956;l to ensure the sucralfate is completely moistened but should not exceed 50 &#956;l.&#160; Greater volume makes the evaporation of the liquid in the next step difficult.</li>
	<li>Place the sucralfate mixture into the centrifugal evaporator set on low until the mixture is completely dry, normally 30-50 min depending on the volume of liquid used.
	<ol>
		<li>Check the mixture for residual moisture with the tapered end of a sterile spatula.&#160; The mixture should feel &#34;crunchy&#34;.</li>
	</ol>
	</li>
	<li>Use the tapered end of the spatula to break up the sucralfate mixture within the tube.</li>
	<li>Add 10 &#956;l of the hydron to the sucralfate.
	<ol>
		<li>Due to the viscous nature of hydron, cut the end from a 200 &#956;l pipet tip and then draw and release the 10 &#956;l before pipetting up again and adding to sucralfate.</li>
	</ol>
	</li>
	<li>Quickly use bent spatula to mix the hydron and sucralfate and remove from tube.
	<ol>
		<li>Gather the mixture along the bottom side of the tip of the bent spatula and then rotate the tube while drawing the spatula out along the wall of the tube.&#160; The mixture will dry rapidly so this step must be done efficiently.</li>
	</ol>
	</li>
	<li>Spread the mixture onto the prepared mesh using forceps to hold it in place.&#160; The mixture should be an even layer and fill into the holes of the mesh.</li>
	<li>Immerse the bent spatula into the tube containing hydron and use it coat both sides of the mesh.</li>
	<li>Place the coated mesh leaning on side against edge of dish and allow drying at RT for 30-45 min.</li>
	<li>Place the mesh in -20 &#176;C freezer or proceed immediately to next step.&#160; Keep mesh inside dish.</li>
	<li>Place the 35 mm dish inside of the larger petri dish, lid off.&#160; Use the pair of forceps to carefully pull the fibers of the mesh apart over the 35 mm dish.&#160; Stray pellets can be collected from the larger dish at the end.
	<ol>
		<li>Check pellets for uniformity under scope.&#160; The process yields approximately 250 pellets thus the standard dose per pellet for bFGF and VEGF is 80 ng and 200 ng, respectively.</li>
	</ol>
	</li>
	<li>Store pellets in 35 mm dish in -20 &#176;C freezer for up to 3 months.</li>
</ol>
2. Surgical Implantation of Pellets
<ol>
	<li>Set up a surgical area under operating microscope.</li>
	<li>Anesthetize the mouse with avertin (400-500 mg/kg, intraperitoneal) and position the mouse under microscope so eye is visible.&#160; Perform toe pinch to ensure sufficient level of anesthesia.</li>
	<li>Anesthetize the mouse eye by placing 1 drop of proparacaine solution atop eyeball.&#160; Wait 20-30 sec and dab with a gauze pad.</li>
	<li>Proptose the mouse eye with the dulled #1 jewelers forceps being certain to leave skin between forceps and eye.&#160; It is important to judge the pressure applied correctly.&#160; Holding the eye too firmly will cause it to become red and irritated, while too loose a hold will allow eye to move during surgery.</li>
	<li>Use the 30&#176; microknife to make an incision into the cornea approximately 1 mm from the limbus.&#160; The incision should be 1-2 mm in length.&#160; Incision should be deep enough to penetrate beyond the epithelial layer into midstroma but not so deep to rupture the eye.</li>
	<li>Use the von Graef knife to make a pocket perpendicular to the incision.&#160;
	<ol>
		<li>Slide the knife under the corneal layer at the incision site and gently work knife in and move it along the incision to enlarge the space, thus forming the pocket.&#160; It helps to move the mouse as well to be able to work with the curvature of the eye.&#160; Be careful not to push downward with the tip to avoid rupturing the eye.</li>
	</ol>
	</li>
	<li>Wet the #5 jeweler&#39;s forceps with proparacaine and pick a pellet up out of dish.&#160; Place a pellet on the eye.</li>
	<li>Moisten the von Graef knife with proparacaine and transfer some of liquid onto pellet to make it rubbery and pliable.&#160; Remove excess moisture with gauze pad or cotton swab.</li>
	<li>Insert the pellet into the pocket using the von Graef knife to push it inside beneath the cornea layer.&#160; Once the whole pellet is inside, run the flat side of von Graef knife over site to check that the pellet is secure.</li>
	<li>Coat the eye with triple antibiotic ointment.</li>
	<li>Turn the mouse over and repeat surgery in the opposite eye.</li>
</ol>
3. Quantification of Corneal Neovascularization.
Leave animals to develop vessels over a set period of time.&#160; The day of vessel grading depends on growth factor used. Grade bFGF on day 5 and the weaker VEGF on day 6.&#160; The day of implantation is day 0.
<ol>
	<li>Anesthetize the mouse with avertin (400-500 mg/kg, intraperitoneal).</li>
	<li>Use the slit lamp microscope for grading.&#160; One ocular has a reticule, lines within the eyepiece used as a measuring aid to quantify vessel length and distance around the eye&#39;s circumference that the vessels have sprouted.
	<ol>
		<li>Hold the mouse in front of scope, positioning mouse so eye is seen in ocular with pellet directly ahead.&#160; Stabilize the head between thumb and forefinger so skin is tightened on face and eye is slightly proptosed.</li>
	</ol>
	</li>
	<li>Place the y-axis of the reticule along the limbal vessel directly beneath pellet.&#160; Measure the length of vessels branching upward toward pellets.&#160; Record this measurement in tenths of millimeters and designate vessel length (VL) (Figure 1A).</li>
	<li>Turn either the mouse or the reticule so that the distance around the eye that these vessels have sprouted becomes clear.&#160; It is easiest to think of the eye as a clock face with intervals of 1 through 12.&#160; Designate this number clock hour (CH) (Figure 1B).&#160; It can be a whole number or fractions of 0.25 (e.g., 2, 2.25, 2.5 or 2.75). Note: CH is subjective.&#160; For example, some may measure the distance around the eye to include all vessels sprouted from the limbus while others may stop measuring at the point where vessel length is half maximal.&#160; The important factor is to be consistent with how one chooses to grade.</li>
</ol>
<img alt="Figure 1" fo:content-width="5in" fo:src="/files/ftp_upload/51375/51375fig1highres.jpg" src="/files/ftp_upload/51375/51375fig1.jpg" /> 
Figure 1. Quantification of corneal neovascularization. &#160;(A) 80 ng bFGF pellet implanted in C57BL/6J mouse showing slit lamp reticule oriented to measure vessel length. VL = 0.9 mm. (B) Same eye showing slit lamp reticule rotated to measure clock hour.&#160; CH = 3.25.&#160; Calculated vessel area = 1.84 mm2.&#160; These images have been digitally enhanced to allow for the addition of reticule schematic. <a href="https://www.jove.com/files/ftp_upload/51375/51375fig1highres.jpg" target="_blank">Click here to view larger image.</a>
<ol start="5">
	<li>Calculate the vessel area (VA) using the formula below, which is based on the area of an oval (Note, it is helpful to keep this in mind when grading.)&#160; Express VA in millimeters squared.&#160; The formula is as follows: 
	Vessel length x Clock hour x 0.2 &#960; = Vessel area</li>
</ol>

<ol>
	<li>Gospodarowicz, D., Moran, J., Braun, D., Birdwell, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clonal+growth+of+bovine+vascular+endothelial+cells:+fibroblast+growth+factor+as+a+survival+agent.">Clonal growth of bovine vascular endothelial cells: fibroblast growth factor as a survival agent.</a> Proc. Natl. Acad. Sci. USA. 73, 4120-4124 (1976).</li><li>Glaser, B. M., D'Amore, P. A., Seppa, H., Seppa, S., Schiffmann, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adult+tissues+contain+chemoattractants+for+vascular+endothelial+cells.">Adult tissues contain chemoattractants for vascular endothelial cells.</a> Nature. 288, 483-484 (1980).</li><li>Kubota, Y., Kleinman, H. K., Martin, G. R., Lawley, T. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+laminin+and+basement+membrane+in+the+morphological+differentiation+of+human+endothelial+cells+into+capillary-like+structures.">Role of laminin and basement membrane in the morphological differentiation of human endothelial cells into capillary-like structures.</a> J. Cell Biol. 107, 1589-1598 (1988).</li><li>Montesano, R., Orci, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tumor-promoting+phorbol+esters+induce+angiogenesis+in+vitro.">Tumor-promoting phorbol esters induce angiogenesis in vitro.</a> Cell. 42, 469-477 (1985).</li><li>Korff, T., Augustin, H. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Integration+of+endothelial+cells+in+multicellular+spheroids+prevents+apoptosis+and+induces+differentiation.">Integration of endothelial cells in multicellular spheroids prevents apoptosis and induces differentiation.</a> J. Cell Biol. 143, 1341-1352 (1998).</li><li>Nicosia, R. F., Tchao, R., Leighton, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Histotypic+angiogenesis+in+vitro:+light+microscopic,+ultrastructural,+and+radioautographic+studies.">Histotypic angiogenesis in vitro: light microscopic, ultrastructural, and radioautographic studies.</a> In Vitro. 18, 538-549 (1982).</li><li>Wong, K. H., Chan, J. M., Kamm, R. D., Tien, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microfluidic+models+of+vascular+functions.">Microfluidic models of vascular functions.</a> Annu Rev Biomed Eng. 14, 205-230 (2012).</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> Anat. Rec. 28, 281-287 (1924).</li><li>Jain, R. K., Schlenger, K., Hockel, M., Yuan, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+angiogenesis+assays:+progress+and+problems.">Quantitative angiogenesis assays: progress and problems.</a> Nat. Med. 3, 1203-1208 (1997).</li><li>Rogers, M. S., Birsner, A. E., D'Amato, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+mouse+cornea+micropocket+angiogenesis+assay.">The mouse cornea micropocket angiogenesis assay.</a> Nat. Protoc. 2 (10), 2545-2550 (2007).</li><li>Gimbrone, M. A., Leapman, S. B., Cotran, R. S., Folkman, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tumor+dormancy+in+vivo+by+prevention+of+neovascularization.">Tumor dormancy in vivo by prevention of neovascularization.</a> J. Exp. Med. 136, 261-276 (1972).</li><li>Gimbrone, M. A., Cotran, R. S., Leapman, S. B., Folkman, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tumor+growth+and+neovascularization:+an+experimental+model+using+the+rabbit+cornea.">Tumor growth and neovascularization: an experimental model using the rabbit cornea.</a> J. Natl. Cancer Inst. 52, 413-427 (1974).</li><li>Rohan, R. M., Fernandez, A., Udagawa, T., Yuan, J., D'Amato, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetic+heterogeneity+of+angiogenesis+in+mice.">Genetic heterogeneity of angiogenesis in mice.</a> FASEB J. 14 (7), 871-876 (2000).</li><li>Chang, L. 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=Dose-dependent+response+of+FGF-2+for+lymphangiogenesis.">Dose-dependent response of FGF-2 for lymphangiogenesis.</a> Proc Natl Acad Sci U S A. 101 (32), 11658-11663 (2004).</li><li>Udagawa, T., Birsner, A. E., Wood, M., D'Amato, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chronic+suppression+of+angiogenesis+following+radiation+exposure+is+independent+of+hematopoietic+reconstitution.">Chronic suppression of angiogenesis following radiation exposure is independent of hematopoietic reconstitution.</a> Cancer Res. 67 (5), 2040-2045 (2007).</li><li>Turner, P. V., Albassam, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Susceptibility+of+rats+to+corneal+lesions+after+injectable+anesthesia.">Susceptibility of rats to corneal lesions after injectable anesthesia.</a> Med Comp. 55 (2), 175-182 (2005).</li><li>Calderone, L., Grimes, P., Shalev, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acute+reversible+cataract+induced+by+xylazine+and+by+ketamine-xylazine+anesthesia+in+rats+and+mice.">Acute reversible cataract induced by xylazine and by ketamine-xylazine anesthesia in rats and mice.</a> Exp. Eye Res. 42, 331-337 (1986).</li></ol>

The authors have nothing to disclose.

There are several critical steps in performing a successful corneal assay.&#160; The first is making uniform pellets capable of being implanted and stimulating vessels.&#160; The most important parts of pellet preparation are 1) using carrier-free growth factor; 2) ensuring a good mixture of growth factor with the sucralfate and hydron and 3) moving the final mixture swiftly but carefully from the eppendorf tube to the mesh where the pellets are cast.&#160; It is recommended that &#34;dummy&#34; pellets be made without g...

The process of angiogenesis, the formation of new blood vessels form preexisting ones, is highly complex and is regulated by several endogenous factors that control different steps of vessel sprouting and morphogenesis.&#160; Angiogenesis is triggered due to a shift in balance between pro- and anti-angiogenic factors, a balance that normally maintains the vasculature in a quiescent state.&#160; Angiogenesis in adults occurs in certain physiological conditions such as during the female ovarian cycle or in repair processes such as wound healing and tissue regeneration. &#160;However, it is also a hallmark of several pathologies including malignancies, autoimmune conditions and inflammatory diseases. &#160;The involvement of angiogenesis in these physiological and pathological conditions makes it an important subject for research and an attractive target for therapy.
Due to the complexity of angiogenesis and the involvement of several cells and factors in the process, including endothelial cells, pericytes, circulating cells and stromal cells, in vitro models remain limited and cannot recapitulate the unique in vivo microenvironment.&#160; &#160;The main in vitro assays of angiogenesis are largely focused on observing direct effects on endothelial cells and measuring certain steps in angiogenic process under controlled conditions. These assays include the quantification of endothelial cell proliferation1, migration2, network formation3, tube formation4 and sprouting from spheroids5. &#160;Ex vivo models, unlike the in vitro ones, are more complex and incorporate multiple tissue cell types, an example being the aortic ring assay6.&#160; Nevertheless, like other systems, it cannot capture the contribution of circulating cells and the natural stroma of endothelial cells as exists in vivo.&#160; Attempts to study angiogenesis under flow to mimic the in vivo setting are performed using microfluidic systems7, however even these assays, although much improved, are still unable to account for all the compartments existing in vivo.
Due to the limitations of the in vitro and ex vivo angiogenesis models, in vivo models remain the more reliable choices for angiogenesis studies.&#160; Examples of these models include the implantation of transparent chambers, &#34;windows&#34;, that allow the visualization of growing blood vessels under microscope8, injectable subcutaneous implants such as matrigel and vessel formation in normal tissues such as mouse ear and the chicken chorioallantoic membrane (CAM).&#160; However, one of the most acceptable and quantitative in vivo angiogenesis models is the corneal micropocket neovascularization assay described here, which exploits the naturally avascular cornea as a &#34;screen&#34; to visualize and assess new angiogenic growth9.
Here we describe the corneal micropocket assay as developed in mice.&#160; Initially the model was used to measure nonspecific angiogenic stimuli in rabbit corneas. This was done by introducing tumor pieces into the aqueous humor of the anterior chamber of the rabbit eye and measured tumor-induced neovascularization11.
&#160;However, the assay was later evolved to study effects of specific growth factors10 to better specify and standardize the angiogenic effect.&#160;&#160; In order to release the growth factor in the eye, slow-release pellets containing known quantities of angiogenic growth factors were used instead of tissues.&#160; The availability of purified recombinant angiogenic proteins such as bFGF or VEGF enabled their use as specific targets of angiogenesis modulaters12.&#160; Initially, the assay was largely used in rabbits, which are easier to work with due to their size but later the model was translated into mice; a smaller and less expensive animal model.&#160; Shifting from rabbit to mice provided an important advantage of being able to use genetically manipulated animals, thereby creating a new area of research into the genetic components impacting angiogenesis13.&#160; In addition to the more acceptable usage of cornea assay in studying angiogenesis, other biological processes can also being investigated using modified assays.&#160; For example, studies of lymphangiogenesis were made possible through the implantation of low dose bFGF pellets which allowed the visualization of lymphatic vessels through specific molecular markers14.&#160; In addition, this assay has provided a means to evaluate the effects of radiation on angiogenesis15.
In summation, the corneal micropocket angiogenesis assay is a quantitative, reproducible, flexible assessment of angiogenesis in vivo.&#160; A major advantage of this assay is that the measurement of background vessels is unnecessary because the vessels grow on a naturally avascular tissue.&#160; We describe here the protocol of this assay in details and discuss different scenarios which can occur. The assay consists of 3 discrete segments.&#160; Here we will describe the preparation of growth factor-inclusive pellets, the subsequent surgical implantation and finally the method used to quantify the resulting neovascular growth.

<table border="0" cellpadding="0" cellspacing="0" width="612">
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		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Section 1: Pellet preparation</td>
			<td style="width:111px;"></td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Sucralfate</td>
			<td style="width:111px;">Sigma</td>
			<td style="width:119px;">#S0652</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Hydron (aka Poly(2-Hema))</td>
			<td style="width:111px;">Sigma</td>
			<td style="width:119px;">#P3932-10G</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Ethanol</td>
			<td style="width:111px;">Pharmco Products Inc</td>
			<td style="width:119px;">#111000200CSGL</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Growth factors:</td>
			<td style="width:111px;"></td>
			<td style="width:119px;"></td>
			<td>Must be carrier-free (no bovine serum albumin(BSA))</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">&#160;Fibroblast growth factor (FGF)</td>
			<td style="width:111px;">PeproTech</td>
			<td style="width:119px;">#AF-100-18B</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Vascular endothelial growth factor (VEGF)</td>
			<td style="width:111px;">R &#38; D Systems</td>
			<td style="width:119px;">#293-VE-050/CF</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">35 mm dish</td>
			<td style="width:111px;">Becton-Dickson</td>
			<td style="width:119px;">#353001</td>
			<td>Used for storage of pellets</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">10 cm petri dish</td>
			<td style="width:111px;">VWR</td>
			<td style="width:119px;">#25384-342</td>
			<td>Used as work surface for preparing pellets</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Mesh</td>
			<td style="width:111px;">Sefar America</td>
			<td style="width:119px;">#03--300/51</td>
			<td>300 um nitex nylon, cut into cm square pieces and sterilzed in autoclave</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Spatulas</td>
			<td style="width:111px;">Fisher Scientific</td>
			<td style="width:119px;">#21-401-10</td>
			<td>Use tapered end of one to break up pellet mixture. Bend tapered end of other to help remove mixture from microcentrifuge tube.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Microcentrifuge tubes</td>
			<td style="width:111px;">Fisher Scientific</td>
			<td style="width:119px;">#05-408-146</td>
			<td>One for hydron, one for sucralfate</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Jewelers forceps, #5</td>
			<td style="width:111px;">Ambler Surgical</td>
			<td style="width:119px;">#2315E</td>
			<td>Need 2 for pulling mesh apart</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Centrifugal evaporator</td>
			<td style="width:111px;">ThermoSavant</td>
			<td style="width:119px;">DNA110 SpeedVac</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;"></td>
			<td style="width:111px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Section 2: Surgical implantation of pellets</td>
			<td style="width:111px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Operating microscope</td>
			<td style="width:111px;">Zeiss</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">2.5% Avertin</td>
			<td style="width:111px;"></td>
			<td style="width:119px;"></td>
			<td>General anesthetic</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Proparacaine hydrochloride ophthalmic solution 0.5%</td>
			<td style="width:111px;">Falcon</td>
			<td>NDC# 6131401601</td>
			<td>Eye anesthetic</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Triple Antibiotic Ophthalmic Ointment</td>
			<td style="width:111px;">Bausch &#38; Lomb</td>
			<td style="width:119px;">NDC# 2420878055</td>
			<td>Contains neomycin, polymixin and bacitracin</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Ophthalmic microknife, 5 mm</td>
			<td style="width:111px;">Surgistar</td>
			<td style="width:119px;">#924501</td>
			<td>30 degree angle</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">von Graef knife</td>
			<td style="width:111px;">Ambler Surgical</td>
			<td style="width:119px;">#3401E</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Jewelers forceps, #1</td>
			<td style="width:111px;">Ambler Surgical</td>
			<td style="width:119px;">#2301E</td>
			<td>Must be blunted with sharpening stone for proptosing eye</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Jewelers forceps, #5</td>
			<td style="width:111px;">Ambler Surgical</td>
			<td style="width:119px;">#2305E</td>
			<td>For picking up pellets and placing on eye</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Small curved scissors</td>
			<td style="width:111px;">Ambler Surgical</td>
			<td style="width:119px;">#5636E</td>
			<td>For trimming whiskers</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Gauze</td>
			<td style="width:111px;"></td>
			<td style="width:119px;"></td>
			<td>For blotting eye after proparacaine</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;"></td>
			<td style="width:111px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Section 3: Grading of Corneal Neovascularization</td>
			<td style="width:111px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">2.5% Avertin</td>
			<td style="width:111px;"></td>
			<td style="width:119px;"></td>
			<td>General anesthetic</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Slit lamp</td>
			<td style="width:111px;">Nikon</td>
			<td style="width:119px;">FS-2</td>
			<td>Needs an ocular with a reticule to assist in measuring</td>
		</tr>
	</tbody>
</table>

the corneal micropocket assay: a model of angiogenesis in the mouse eye

The mouse corneal micropocket assay is a robust and quantitative in vivo assay for evaluating angiogenesis. By using standardized slow-release pellets containing specific growth factors that trigger blood vessel growth throughout the naturally avascular cornea, angiogenesis can be measured and quantified. In this assay the angiogenic response is generated over the course of several days, depending on the type and dose of growth factor used. The induction of neovascularization is commonly triggered by either basic fibroblast growth factor (bFGF) or vascular endothelial growth factor (VEGF). By combining these growth factors with sucralfate and hydron (poly-HEMA (poly(2-hydroxyethyl methacrylate))) and casting the mixture into pellets, they can be surgically implanted in the mouse eye. These uniform pellets slowly-release the growth factors over five or six days (bFGF or VEGF respectively) enabling sufficient angiogenic response required for vessel area quantification using a slit lamp. This assay can be used for different applications, including the evaluation of angiogenic modulator drugs or treatments as well as comparison between different genetic backgrounds affecting angiogenesis. A skilled investigator after practicing this assay can implant a pellet in less than 5 min per eye.

Typical results for bFGF and VEGF pellets in the normal low angiogenic C57BL/6J mice are shown in Figure 2A and B, respectively.&#160; Figure 2E shows the normal distribution of vessel area (VA) in the C57BL/6J strain with varying doses of these growth factors.&#160; 80 ng bFGF pellets normally result in a VA of approximately 2.0 mm2, though values in a range of 1.8-2.4 mm2 are acceptable.&#160; 200 ng VEGF pellets typically cause a response of appr...

Watch this Scientific Journal Video about The Corneal Micropocket Assay: A Model of Angiogenesis in the Mouse Eye at JoVE.com

The Corneal Micropocket Assay: A Model of Angiogenesis in the Mouse Eye

The protocol describes the corneal micropocket assay as developed in mice.

The mouse corneal micropocket assay is a robust and quantitative in vivo assay for evaluating angiogenesis. By using standardized slow-release pellets ...

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16.6K Views.  Boston Children's Hospital. The protocol describes the corneal micropocket assay as developed in mice.

Video: The Corneal Micropocket Assay: A Model of Angiogenesis in the Mouse Eye

Trypsin Digest Protocol to Analyze the Retinal Vasculature of a Mouse Model

Trypsin digest is the gold standard method to analyze the retinal vasculature 1-5. It allows visualization of the entire network of complex three-dimensional retinal blood vessels and capillaries by creating a two-dimensional flat-mount of the interconnected vascular channels after digestion of the non-vascular components of the retina. This allows one to study various pathologic vascular changes, such as microaneurysms, capillary degeneration, and abnormal endothelial to pericyte ratios. However, the method is technically challenging, especially in mice, which have become the most widely available animal model to study the retina because of the ease of genetic manipulations 6,7. In the mouse eye, it is particularly difficult to completely remove the non-vascular components while maintaining the overall architecture of the retinal blood vessels. To date, there is a dearth of literature that describes the trypsin digest technique in detail in the mouse. This manuscript provides a detailed step-by-step methodology of the trypsin digest in mouse retina, while also providing tips on troubleshooting difficult steps.

Trypsin digest is one of the most commonly used methods to analyze retinal vasculature. This manuscript describes the method in detail, including key alterations to optimize the technique and remove the non-vascular tissue while preserving the overall architecture of the vessels.

Trypsin digest is the gold standard method to analyze the retinal vasculature 1-5. It allows visualization of the entire network of complex ...

Whole Mount Immunofluorescent Staining of the Neonatal Mouse Retina to Investigate Angiogenesis In vivo

Angiogenesis is the complex process of new blood vessel formation defined by the sprouting of new blood vessels from a pre-existing vessel network. Angiogenesis plays a key role not only in normal development of organs and tissues, but also in many diseases in which blood vessel formation is dysregulated, such as cancer, blindness and ischemic diseases. In adult life, blood vessels are generally quiescent so angiogenesis is an important target for novel drug development to try and regulate new vessel formation specifically in disease. In order to better understand angiogenesis and to develop appropriate strategies to regulate it, models are required that accurately reflect the different biological steps that are involved. The mouse neonatal retina provides an excellent model of angiogenesis because arteries, veins and capillaries develop to form a vascular plexus during the first week after birth. This model also has the advantage of having a two-dimensional (2D) structure making analysis straightforward compared with the complex 3D anatomy of other vascular networks. By analyzing the retinal vascular plexus at different times after birth, it is possible to observe the various stages of angiogenesis under the microscope. This article demonstrates a straightforward procedure for analyzing the vasculature of a mouse retina using fluorescent staining with isolectin and vascular specific antibodies.

Whole Mount Immunofluorescent Staining of the Neonatal Mouse Retina to Investigate Angiogenesis In vivo

The neonatal murine retina provides a well characterized physiological model of angiogenesis, which permits investigations of the roles of different genes or drugs that modulate angiogenesis in an in vivo context. Immunofluorescent staining to accurately visualize the vascular plexus is pivotal to the success of these types of studies.

Angiogenesis  is the complex process of new blood vessel formation defined by the sprouting  of new blood vessels from a pre-existing vessel network. ...

Isolation and Culture of Endothelial Cells from the Embryonic Forebrain

Embryonic brain endothelial cells can serve as an important tool in the study of angiogenesis and neurovascular development and interactions. The two vascular networks of the embryonic forebrain, pial and periventricular, are spatially distinctive and have different origins and growth patterns. Endothelial cells from the pial and periventricular vascular networks have unique gene expression profiles and functions. Here we present a step-by-step protocol for isolation, culture, and verification of pure populations of endothelial cells from the periventricular vascular network (PVECs) of the embryonic forebrain (telencephalon). In this approach, telencephalon devoid of pial membrane obtained from embryonic day 15 mice is minced, digested with collagenase/dispase, and dispersed mechanically into a single cell suspension. PVECs are purified from cell suspension using positive selection with anti-CD-31/PECAM-1 antibody conjugated to MicroBeads using a strong magnetic separation method. Purified cells are cultured on collagen 1&#160;coated culture dishes in endothelial cell culture medium until they become confluent and further subcultured. PVECs obtained with this protocol exhibit cobblestone and spindle shaped phenotypes, as visualized by phase-contrast light microscopy and fluorescence microscopy. Purity of PVEC cultures was established with endothelial cell markers. In our hands, this method reliably and consistently yields pure populations of PVECs. This protocol will benefit studies aimed at gaining mechanistic insights into forebrain angiogenesis, understanding PVEC interactions, and cross-talks with neuronal cell types and holds tremendous potential for therapeutic angiogenesis.

This video demonstrates an easy and reliable strategy for preparation of pure cultures of endothelial cells from the embryonic forebrain within 10-12 days and will be useful for research focused on many aspects of cerebral angiogenesis.

Embryonic brain endothelial cells can serve as an important tool in the study of angiogenesis and neurovascular development and interactions. The two ...

A Simple Behavioral Assay for Testing Visual Function in Xenopus laevis

Measurement of the visual function in the tadpoles of the frog, Xenopus laevis, allows screening for blindness in live animals. The optokinetic response is a vision-based, reflexive behavior that has been observed in all vertebrates tested. Tadpole eyes are small so the tail flip response was used as alternative measure, which requires a trained technician to record the subtle response. We developed an alternative behavior assay based on the fact that tadpoles prefer to swim on the white side of a tank when placed in a tank with both black and white sides. The assay presented here is an inexpensive, simple alternative that creates a response that is easily measured. The setup consists of a tripod, webcam and nested testing tanks, readily available in most Xenopus laboratories. This article includes a movie showing the behavior of tadpoles, before and after severing the optic nerve. In order to test the function of one eye, we also include representative results of a tadpole in which each eye underwent retinal axotomy on consecutive days. Future studies could develop an automated version of this assay for testing the vision of many tadpoles at once.

A Simple Behavioral Assay for Testing Visual Function in Xenopus laevis

Xenopus laevis tadpoles prefer swimming on the white side of a black/white tank. This behavior is guided by their vision. Based on this behavior, we present a simple assay to test the visual function of tadpoles.

Measurement of the visual function in the tadpoles of the frog, Xenopus laevis, allows screening for blindness in live animals. The optokinetic response ...

Telomerase Activity in the Various Regions of Mouse Brain: Non-Radioactive Telomerase Repeat Amplification Protocol (TRAP) Assay

Telomerase, a ribonucleoprotein, is responsible for maintaining the telomere length and therefore promoting genomic integrity, proliferation, and lifespan. In addition, telomerase protects the mitochondria from oxidative stress and confers resistance to apoptosis, suggesting its possible importance for the surviving of non-mitotic, highly active cells such as neurons. We previously demonstrated the ability of novel telomerase activators to increase telomerase activity and expression in the various mouse brain regions and to protect motor neurons cells from oxidative stress. These results strengthen the notion that telomerase is involved in the protection of neurons from various lesions. To underline the role of telomerase in the brain, we here compare the activity of telomerase in male and female mouse brain and its dependence on age. TRAP assay is a standard method for detecting telomerase activity in various tissues or cell lines. Here we demonstrate the analysis of telomerase activity in three regions of the mouse brain by non-denaturing protein extraction using CHAPS lysis buffer followed by modification of the standard TRAP assay.
In this 2-step assay, endogenous telomerase elongates a specific telomerase substrate (TS primer) by adding TTAGGG 6 bp repeats (telomerase reaction). The telomerase reaction products are amplified by PCR reaction creating a DNA ladder of 6 bp increments. The analysis of the DNA ladder is made by 4.5% high resolution agarose gel electrophoresis followed by staining with highly sensitive nucleic acid stain.
Compared to the traditional TRAP assay that utilize 32P labeled radioactive dCTP&#39;s for DNA detection and polyacrylamide gel electrophoresis for resolving the DNA ladder, this protocol offers a non-toxic time saving TRAP assay for evaluating telomerase activity in the mouse brain, demonstrating the ability to detect differences in telomerase activity in the various female and male mouse brain region.

Telomerase Activity in the Various Regions of Mouse Brain: Non-Radioactive Telomerase Repeat Amplification Protocol TRAP Assay

Telomerase is expressed in the neonatal brain and also in distinct regions of the adult brain. We present a non-toxic time saving TRAP assay for the analysis of telomerase activity in various regions of the mouse brain and detection of differences in telomerase activity between male and female mouse brains.

Telomerase, a ribonucleoprotein, is responsible for maintaining the telomere length and therefore promoting genomic integrity, proliferation, and ...

A Volumetric Method for Quantification of Cerebral Vasospasm in a Murine Model of Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a subtype of hemorrhagic stroke. Cerebral vasospasm that occurs in the aftermath of the bleeding is an important factor determining patient outcome and is therefore frequently taken as a study endpoint. However, in small animal studies on SAH, quantification of cerebral vasospasm is a major challenge. Here, an ex vivo method is presented that allows quantification of volumes of entire vessel segments, which can be used as an objective measure to quantify cerebral vasospasm. In a first step, endovascular casting of the cerebral vasculature is performed using a radiopaque casting agent. Then, cross-sectional imaging data are acquired by micro computed tomography. The final step involves 3-dimensional reconstruction of the virtual vascular tree, followed by an algorithm to calculate center lines and volumes of the selected vessel segments. The method resulted in a highly accurate virtual reconstruction of the cerebrovascular tree shown by a diameter-based comparison of anatomical samples with their virtual reconstructions. Compared with vessel diameters alone, the vessel volumes highlight the differences between vasospastic and non-vasospastic vessels shown in a series of SAH and sham-operated mice.

The goal of this article is to present a method that allows a 3-dimensional reconstruction of the cerebrovascular tree in mice after micro computed tomography and determination of volumes of entire vessel segments that can be used to quantify cerebral vasospasm in murine models of subarachnoid hemorrhage.

Subarachnoid hemorrhage (SAH) is a subtype of hemorrhagic stroke. Cerebral vasospasm that occurs in the aftermath of the bleeding is an important factor ...

Characterizing the Relationship Between Eye Movement Parameters and Cognitive Functions in Non-demented Parkinson's Disease Patients with Eye Tracking

Cognitive impairment is a common phenomenon in Parkinson&#8217;s disease that has implications on the prognosis. A simple, noninvasive and objective proxy measurement of cognitive function in Parkinson&#8217;s disease will be helpful in detecting early cognitive decline. As a physiological metric, eye movement parameter is not confounded by the subject&#39;s attributes and intelligence and can function as a proxy marker if it correlates with cognitive functions. To this end, this study explored the relationship between the eye movement parameters and performance in cognitive tests in multiple domains. In the experiment, a visual search task with eye tracking was set up, where subjects were asked to look for a number embedded in an array of alphabets scattered randomly on a computer screen. The differentiation between the number and the alphabet is an overlearned task such that the confounding effect of cognitive ability on the eye movement parameters is minimized. The average saccadic amplitude and fixation duration were captured and calculated during the visual search task. The cognitive assessment battery covered domains of frontal-executive functions, attention, verbal and visual memory. It was found that prolonged fixation duration was associated with poorer performance in verbal fluency, visual and verbal memory, allowing further exploration on the use of eye movement parameters as proxy markers for cognitive function in Parkinson&#8217;s disease patients. The experimental paradigm has been found to be highly tolerable in our group of Parkinson&#39;s disease patients and could be applied transdiagnostically to other disease entities for similar research questions.

Here, we present a protocol to study the relationship between the eye movement parameters and cognitive functions in non-demented Parkinson&#39;s disease patients. The experiment used an eye tracker to measure the saccadic amplitude and fixation duration in a visual search task. The correlation with performance in multi-domain cognitive tasks was subsequently measured.

Cognitive impairment is a common phenomenon in Parkinson&#8217;s disease that has implications on the prognosis. A simple, noninvasive and objective proxy ...

A Rapid Food-Preference Assay in Drosophila

To select food with nutritional value while avoiding the consumption of harmful agents, animals need a sophisticated and robust taste system to evaluate their food environment. The fruit fly, Drosophila melanogaster, is a genetically tractable model organism that is widely used to decipher the molecular, cellular, and neural underpinnings of food preference. To analyze fly food preference, a robust feeding method is needed. Described here is a two-choice feeding assay, which is rigorous, cost-saving, and fast. The assay is Petri-dish-based and involves the addition of two different foods supplemented with blue or red dye to the two halves of the dish. Then, ~70 prestarved, 2-4-day-old flies are placed in the dish and&#160;allowed to choose between blue and red foods in the dark for about 90 min. Examination of the abdomen of each fly is followed by the calculation of the preference index. In contrast to multiwell plates, each Petri dish takes only ~20 s to fill and saves time and effort. This feeding assay can be employed to quickly determine whether flies like or dislike a particular food.

A Rapid Food-Preference Assay in Drosophila

We present a protocol for a two-choice feeding assay for flies. This feeding assay is fast and easy to run and is suitable not only for small-scale laboratory research, but also for high-throughput behavioral screens in flies.

To select food with nutritional value while avoiding the consumption of harmful agents, animals need a sophisticated and robust taste system to evaluate ...

Optimizing the Setup and Conditions for Ex Vivo Electroretinogram to Study Retina Function in Small and Large Eyes

Measurements of retinal neuronal light responses are critical to investigating the physiology of the healthy retina, determining pathological changes in retinal diseases, and testing therapeutic interventions. The ex vivo electroretinogram (ERG) allows the quantification of contributions from individual cell types in the isolated retina by addition of specific pharmacological agents and evaluation of tissue-intrinsic changes independently of systemic influences. Retinal light responses can be measured using a specialized ex vivo ERG specimen holder and recording setup, modified from existing patch clamp or microelectrode array equipment. Particularly, the study of ON-bipolar cells, but also of photoreceptors, has been hampered by the slow but progressive decline of light responses in the ex vivo ERG over time. Increased perfusion speed and adjustment of the perfusate temperature improve ex vivo retinal function and maximize response amplitude and stability. The ex vivo ERG uniquely allows the study of individual retinal neuronal cell types. In addition, improvements to maximize response amplitudes and stability allow the investigation of light responses in retina samples from large animals, as well as human donor eyes, making the ex vivo ERG a valuable addition to the repertoire of techniques used to investigate retinal function.

Optimizing the Setup and Conditions for Ex Vivo Electroretinogram to Study Retina Function in Small and Large Eyes

Modification of existing multielectrode array or patch clamp equipment makes the ex vivo electroretinogram more widely accessible. Improved methods to record and maintain ex vivo light responses facilitate the study of photoreceptor and ON-bipolar cell function in the healthy retina, animal models of eye diseases, and human donor retinas.

Measurements of retinal neuronal light responses are critical to investigating the physiology of the healthy retina, determining pathological changes in ...

Evaluating Optokinetic Reflex Responses in Mice: A New High-Precision Protocol

Quantification of Visual Feature Selectivity of the Optokinetic Reflex in Mice

The optokinetic reflex (OKR) is an essential innate eye movement that is triggered by the global motion of the visual environment and serves to stabilize retinal images. Due to its importance and robustness, the OKR has been used to study visual-motor learning and to evaluate the visual functions of mice with different genetic backgrounds, ages, and drug treatments. Here, we introduce a procedure for evaluating OKR responses of head-fixed mice with high accuracy. Head fixation can rule out the contribution of vestibular stimulation on eye movements, making it possible to measure eye movements triggered only by visual motion. The OKR is elicited by a virtual drum system, in which a vertical grating presented on three computer monitors drifts horizontally in an oscillatory manner or unidirectionally at a constant velocity. With this virtual reality system, we can systematically change visual parameters like spatial frequency, temporal/oscillation frequency, contrast, luminance, and the direction of gratings, and quantify tuning curves of visual feature selectivity. High-speed infrared video-oculography ensures accurate measurement of the trajectory of eye movements. The eyes of individual mice are calibrated to provide opportunities to compare the OKRs between animals of different ages, genders, and genetic backgrounds. The quantitative power of this technique allows it to detect changes in the OKR when this behavior plastically adapts due to aging, sensory experience, or motor learning; thus, it makes this technique a valuable addition to the repertoire of tools used to investigate the plasticity of ocular behaviors.

Author Spotlight: An Accurate and Quantitative Approach to Study Visual Feature Selectivity of the Optokinetic Reflex in Mice 

Here, we describe a standard protocol for quantifying the optokinetic reflex. It combines virtual drum stimulation and video-oculography, and thus allows precise evaluation of the feature selectivity of the behavior and its adaptive plasticity.

The optokinetic reflex (OKR) is an essential innate eye movement that is triggered by the global motion of the visual environment and serves to stabilize ...