This study was supported in part by grant 1304/20 from the Israel Science Foundation (ISF), Israel, for Arie Marcovich. We thank Shahar Ish-Shalom&#160;and Ady Yosipovich, from the Department of Pathology, Kaplan Medical Center, Rehovot, Israel, for histology analysis.

The experiments in the protocol were approved by the Israeli National Council on Animal Experimentation and comply with the ARVO Statement for using Animals in Ophthalmic and Vision Research. Female C57BL/6 mice, aged 8-10 weeks, were used for the present study and were exposed to 12/12 h light-dark cycles. The animals were obtained from a commercial source (see Table of Materials).
1. Cell culture
<ol>
	<li>Culture B16LS9 cells in RPMI 1640 medium, suppleme...

<ol>
	<li>Jager, M. 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=Uveal+melanoma.">Uveal melanoma.</a> Nature Reviews Disease Primers. 6 (1), 1-25 (2020).</li><li>Bustamante, P., Piquet, L., Landreville, S., Burnier, J. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Uveal+melanoma+pathobiology:+Metastasis+to+the+liver.">Uveal melanoma pathobiology: Metastasis to the liver.</a> Seminars in Cancer Biology. 71, 65-85 (2021).</li><li>Damato, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ocular+treatment+of+choroidal+melanoma+in+relation+to+the+prevention+of+metastatic+death-A+personal+view.">Ocular treatment of choroidal melanoma in relation to the prevention of metastatic death-A personal view.</a> Progress in Retinal and Eye Research. 66, 187-199 (2018).</li><li>Jouhi, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+small+fatal+choroidal+melanoma+study.+A+survey+by+the+European+Ophthalmic+Oncology+Group.">The small fatal choroidal melanoma study. A survey by the European Ophthalmic Oncology Group.</a> American Journal of Ophthalmology. 202, 100-108 (2019).</li><li>Cao, J., Jager, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+eye+models+for+uveal+melanoma.">Animal eye models for uveal melanoma.</a> Ocular Oncology and Pathology. 1 (3), 141-150 (2015).</li><li>Uner, O. E., Gandrakota, N., Azarcon, C. P., Grossniklaus, H. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+models+of+uveal+melanoma.">Animal models of uveal melanoma.</a> Annals of Eye Science. 7, 21-30 (2022).</li><li>Yang, H., Dithmar, S., Grossniklaus, H. 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M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Murine+models+of+liver+metastasis.">Murine models of liver metastasis.</a> Invasion &amp; Metastasis. 14 (1-6), 349-361 (1994).</li><li>Ashur-Fabian, O., 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=Tetrac+delayed+the+onset+of+ocular+melanoma+in+an+orthotopic+mouse+model.">Tetrac delayed the onset of ocular melanoma in an orthotopic mouse model.</a> Frontiers in Endocrinology. 12, 632335 (2019).</li><li>Elia, G., 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=Mechanisms+regulating+c-met+overexpression+in+liver-metastatic+B16-LS9+melanoma+cells.">Mechanisms regulating c-met overexpression in liver-metastatic B16-LS9 melanoma cells.</a> Journal of Cellular Biochemistry. 81 (3), 477-487 (2001).</li><li>Harning, R., Szalay, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ocular+metastasis+of+in+vivo+and+in+vitro+derived+syngeneic+murine+melanoma.">Ocular metastasis of in vivo and in vitro derived syngeneic murine melanoma.</a> Investigative Ophthalmology &amp; Visual Science. 28 (9), 1599-1604 (1987).</li><li>Ezra-Elia, 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=Can+an+in+vivo+imaging+system+be+used+to+determine+localization+and+biodistribution+of+AAV5-mediated+gene+expression+following+subretinal+and+intravitreal+delivery+in+mice.">Can an in vivo imaging system be used to determine localization and biodistribution of AAV5-mediated gene expression following subretinal and intravitreal delivery in mice.</a> Experimental Eye Research. 176, 227-234 (2018).</li><li>Notting, I. 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=Whole-body+bioluminescent+imaging+of+human+uveal+melanoma+in+a+new+mouse+model+of+local+tumor+growth+and+metastasis.">Whole-body bioluminescent imaging of human uveal melanoma in a new mouse model of local tumor growth and metastasis.</a> Investigative Ophthalmology &amp; Visual Science. 46 (5), 1581-1587 (2005).</li><li>Yang, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In-vivo+xenograft+murine+human+uveal+melanoma+model+develops+hepatic+micrometastases.">In-vivo xenograft murine human uveal melanoma model develops hepatic micrometastases.</a> Melanoma Research. 18 (2), 95-103 (2008).</li><li>Murthy, R. K., Haji, S., Sambhav, K., Grover, S., Chalam, K. 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S., Waheed, N. K., Goldman, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Handbook of Retinal OCT: Optical Coherence Tomography, 2nd Edition. , (2021).</li><li>Tomayko, M. M., Reynolds, C. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Determination+of+subcutaneous+tumor+size+in+athymic+(nude)+mice.">Determination of subcutaneous tumor size in athymic (nude) mice.</a> Cancer Chemotherapy and Pharmacology. 24 (3), 148-154 (1989).</li><li>Richards, J. R., Yoo, J. H., Shin, D., Odelberg, S. 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Marcovich A.L.: Steba Biotech (P), Yeda Weizmann (P), EyeYon Medical (C, P), Mor Isum (P). (C) = Consultant; (P) = Patent. All other authors have no competing interests.

Uveal melanoma is a devastating disease for which novel therapeutic approaches are greatly needed. However, research on uveal melanoma and potential treatments is limited by the technical challenges of uveal melanoma animal models1,25. Ocular tumors, which are induced by intraocular injection of cancer cells, are highly variable in both localization and size, likely due to the small dimensions of the mouse eye. Such variability is an obstacle to the comprehensive...

Uveal melanoma (UM) is the most frequent intraocular primary malignancy in adults. Approximately 90% of ocular melanomas originate from melanocytes in the choroid region of the uveal tract1. UM is a major cause of morbidity and mortality, as it is estimated that close to 50% of patients develop metastatic disease, with the liver being the major site of metastasis2. Early treatment of primary lesions may reduce the chance of metastases, yet no effective treatment prevents metastases formation3.
The standard treatment of uveal melanoma includes irradiation therapy, which is associated with loss of vision due to optic neuropathy, retinopathy, dry eye syndrome, and cataract. Surgical resection is typically delayed until the growth of the lesion is recognized and characterized. However, such a delay may allow metastatic disease development4. In some cases, futile enucleation is required. Of course, this radical procedure compromises vision and results in dramatic aesthetic deterioration.
There have been many efforts dedicated to developing experimental models to study uveal melanoma. Preclinical animal models that allow accurate assessment of this malignancy are key for investigating novel diagnostic and therapeutic strategies for uveal melanoma. Experimental animal models of ocular melanoma are mainly based on the inoculation of tumor cells in mice, rats, and rabbits5,6. Mouse models are cost-effective and widely used for melanoma studies due to their rapid reproduction rate and high genome similarity to humans. The murine cutaneous melanoma cell line B16 is commonly utilized to inoculate C57BL6 mice and induce syngeneic tumors. When using this model to induce uveal melanoma, tumor-bearing eyes typically need to be enucleated 7-14 days after inoculation. Further, B16 is a highly invasive model. The immune-privileged nature of the eye supports metastasis, and metastases may typically be detected 3-4 weeks after tumor cell inoculation. Subcultures of the original B16 line display distinct metastatic properties6. For example, the Queens melanoma line has a high metastatic rate7,8. The B16LS9 cell line has dendritic cell morphology and was derived from liver metastases of C57BL/6 mice injected with the parental cutaneous melanoma line B16F19. When injected into the posterior compartment of the eye, these cells were shown to form intraocular tumors, which histologically resemble human uveal melanoma and form liver-specific metastases in C57BL/6, but not Balb/C, mice10,11,12. Genetically, the cells are characterized by higher expression of the c-met proto-oncogene, which acts as a cellular receptor for hepatocyte growth factor13. In contrast, B16F10, the 10th passage of the parental B16, primarily metastasizes to the lungs when inoculated intraocularly14.&#160;Both B16F10 and B16LS9 are pigmented12.
Several key challenges limit the success of murine uveal melanoma models. First, tumor cell reflux may lead to extraocular or subconjunctival melanoma. Second, tumor growth after intraocular inoculation of melanoma cells is often highly variable, posing difficulties in evaluating treatment and progress. Another major difficulty is the limited ability to follow tumor growth in vivo. While bioluminescent imaging, such as of luciferase expressing tumors, is commonly used to monitor ocular tumor growth15,16, it cannot provide information on the intraocular location of the tumor. Therefore, evaluation of the tumor is typically performed following enucleation of the eye10,17. This greatly limits the ability to characterize tumor progression and response to treatments extensively. Another major hurdle in studying uveal melanoma is the difficulty in monitoring lesions in pigmented mice. New approaches, which overcome these difficulties, are required to promote the research of uveal melanoma in animal models.
Optical coherence tomography (OCT) provides distinctive capabilities to image deep into the different sections of the eye in high resolution, which is unparalleled by other methodologies, including&#160;ultrasound18,19. OCT imaging has been used in animal models to study various ocular diseases20. Recently, OCT imaging was demonstrated as noninvasive means to evaluate intraocular tumor growth21. The protocol described here depicts the implantation of melanoma cells in the murine choroid and the utilization of OCT to predict intraocular tumor localization and size at the time of cell inoculation.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>10 &#956;L glass syringe (Hamilton Co., Bonaduz, Switzerland)</td>
			<td>Hamilton</td>
			<td>721711</td>
			<td></td>
		</tr>
		<tr>
			<td>30 G needles</td>
			<td>BD Microbalance</td>
			<td>2025-01</td>
			<td></td>
		</tr>
		<tr>
			<td>Atipamezole hydrochloride</td>
			<td>Orion Phrma</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>B16LS9 cells</td>
			<td>from Hans Grossniklaus USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Buprenorphine&#160;</td>
			<td>richter pharma</td>
			<td>102047</td>
			<td></td>
		</tr>
		<tr>
			<td>C57BL/6 female mice</td>
			<td>Envigo</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Essential vitamin mixture</td>
			<td>satorius</td>
			<td>01-025-1A</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal bovine serum</td>
			<td>rhenium</td>
			<td>10270106</td>
			<td></td>
		</tr>
		<tr>
			<td>HEPES</td>
			<td>satorius</td>
			<td>03-025-1B</td>
			<td></td>
		</tr>
		<tr>
			<td>Hydroxyethylcellulose 1.4% eye drops</td>
			<td>Fisher Pharmaceutical</td>
			<td>390862</td>
			<td></td>
		</tr>
		<tr>
			<td>InSight OCT segmentation software&#160;</td>
			<td>Phoenix Micron, Inc&#160;</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ketamine</td>
			<td>bremer pharma GMBH (medimarket)</td>
			<td>17889</td>
			<td></td>
		</tr>
		<tr>
			<td>L-glutamine</td>
			<td>satorius</td>
			<td>03-020-1B</td>
			<td></td>
		</tr>
		<tr>
			<td>Medetomidine&#160;</td>
			<td>zoetis (vetmarket)</td>
			<td>102532</td>
			<td></td>
		</tr>
		<tr>
			<td>Ofloxacin 0.3% eye drops</td>
			<td>allergan</td>
			<td>E92170</td>
			<td></td>
		</tr>
		<tr>
			<td>Optical coherence tomography&#160;</td>
			<td>Phoenix Micron, Inc&#160;</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Oxybuprocaine 0.4%</td>
			<td>Fisher Pharmaceutical</td>
			<td>393050</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin-streptomycin-amphoteracin</td>
			<td>satorius</td>
			<td>03-033-1B</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate buffered saline (PBS)&#160;</td>
			<td>satorius</td>
			<td>02-023-1a</td>
			<td></td>
		</tr>
		<tr>
			<td>RPMI cell media</td>
			<td>satorius</td>
			<td>01-104-1A</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium pyruvate</td>
			<td>satorius</td>
			<td>03-042-1B</td>
			<td></td>
		</tr>
		<tr>
			<td>Surgical microscope</td>
			<td>Zeiss</td>
			<td>OPMI-6 CFC</td>
			<td></td>
		</tr>
		<tr>
			<td>Tropicamide 0.5%</td>
			<td>Fisher Pharmaceutical</td>
			<td>390723</td>
			<td></td>
		</tr>
	</tbody>
</table>

implantation and evaluation of melanoma in the murine choroid via optical coherence tomography

Establishing experimental choroidal melanoma models is challenging in terms of the ability to induce tumors at the correct localization. In addition, difficulties in observing posterior choroidal melanoma in vivo limit tumor location and growth evaluation in real-time. The approach described here optimizes techniques for establishing choroidal melanoma in mice via a multi-step sub-choroidal B16LS9 cell injection procedure. To enable precision in injecting into the small dimensions of the mouse uvea, the complete procedure is performed under a microscope. First, a conjunctival peritomy is formed in the dorsal-temporal area of the eye. Then, a tract into the sub-choroidal space is created by inserting a needle through the exposed sclera. This is followed by the insertion of a blunt needle into the tract and the injection of melanoma cells into the choroid. Immediately after injection, noninvasive optical coherence tomography (OCT) imaging is utilized to determine tumor location and progress. Retinal detachment is evaluated as a predictor of tumor site and size. The presented method enables the reproducible induction of choroid-localized melanoma in mice and the live imaging of tumor growth evaluation. As such, it provides a valuable tool for studying intraocular tumors.

Eyes were examined via OCT immediately after injection of the B16LS9 cells. Local retinal detachment was observed after injection. The mice exhibited three patterns of RD: focal (Figure 2, upper panel), leakage to the vitreous (Figure 2, middle panel), and extended RD (Figure 2, bottom panel). Extended RD is likely caused by damage from the injection. There was an association between the pattern of RD immediately after inje...

Watch this Scientific Journal Video about Implantation and Evaluation of Melanoma in the Murine Choroid via Optical Coherence Tomography at JoVE.com

Implantation and Evaluation of Melanoma in the Murine Choroid via Optical Coherence Tomography

The present protocol describes the implantation and evaluation of melanoma in the murine choroid utilizing optical coherence tomography.

Implantation and Evaluation of Melanoma in the Murine Choroid via Optical Coherence Tomography

Establishing experimental choroidal melanoma models is challenging in terms of the ability to induce tumors at the correct localization. In addition, ...

Establishing tumors as the posterior part of the eye is challenging. This method enables the induction of reproducible choroidal melanoma tumors in mice, and live imaging of tumor growth for evaluation. This protocol utilizes OCT live imaging to assess the location of the tumors already at the time of tumor cell inoculation, and to follow tumor growth in live animals.Uveal melanoma is a devastating disease with close to a 50%rate of metastasis. Developing experimental models is key to advancing research aimed at new therapeutic possibilities. An advantage of this method is that the immediate assessment of the success of injection allows to reach study groups with homogenous tumors and continuously follow them by live imaging.To examine tumor progression. Injecting into the small mouse's eyes requires practice. The ability to visualize the injected cells allows you to assess your success immediately and repeat with more mice as necessary.Demonstrating the procedure will be Dr.Dimitri Gaber from the Ophthalmology Research Laboratory at the Kaplan Medical Center. To begin, apply 0.4%topical ophthalmic anesthetic, Oxybuprocaine to both eyes of the anesthetized mouse. Then topically apply 0.5%Tropicamide to both eyes for dilating the pupils, followed by 1.4%hydroxyethyl cellulose as a lubricant to avoid drying of the eyes.Observe one eye of the mouse under an operating microscope. Hold the eyelids open with sterile intraocular forceps. Then hold the superior temporal limbo-conjunctiva and pull toward an infra nasal position.Secure this position by holding the limbo-conjunctiva throughout the procedure. Using a 30 gauge needle tip make a small conjunctival peritomy in the dorsal temporal area approximately one to two millimeters posterior to the limbus. Remove the excess tendons capsule from the opening of the peritomy.Insert the needle tip to penetrate the sclera creating a track into the subchoroidal space until the brown color of the choroid appears through the exposed white matter of the sclera. Load the cells into a sterile 10 microliter glass Hamilton syringe mounted with a 32 gauge blunt needle twisted at a 45 degree angle. Insert the needle of the loaded syringe approximately two millimeters into the created tract, and inject two microliters of the cell suspension.Hold the needle in place after injection for two to three seconds until all fluid has cleared. Remove the needle by pulling it out gently to avoid leakage from the tract. Immediately after the melanoma cell inoculation, observe the injected eye of the animal by OCT scans.Based on the scans, classify the retinal detachment or RD patterns according to three categories local RD, Leakage Into The Vitreous, or Extended RD.Open an OCT segmentation analysis software to predict the tumor size based on RD height. Measure the height of Local RD in the OCT scans, and classify them into three groups. In the postoperative phase, apply 0.3%of Ofloxacin topically.The OCT-based prediction of tumor growth following subchoroidal cell injection is depicted in this figure. The mice exhibited three patterns of RD, Focal, Leakage To The Vitreous, and Extended RD.There was an association between the pattern of RD immediately after injection, and the localization of the tumors five days after injection. Focal RD was associated with the tumor cell growth that was limited to the choroid.However, observation of cells in the vitreous after injection in animals displaying Focal RD indicated tumor growth in the vitreal cavity and the choroid. when Extended RD was observed after injection, tumors were dispersed throughout the choroid and vitreous after five days. The range of tumor sizes induced in this model can be divided into small, medium, and large.Shown here are representative images of the OCT measurement of RD height after injection, and the corresponding fundus image, a horizontal OCT scan of the tumor height and width on day five after injection, and its corresponding fundus image, and the corresponding H&E stained eye section demonstrating comparable tumor measurements. Tumor volume measurements of mice that presented small, medium or large RD immediately after cell injection are presented here. Adjusting the force of injection can affect tumor size and location.It is important to calibrate this and to evaluate the pattern of induced retinal detachment by OCT after injection. Live imaging of choroidal tumors is an important experimental tool that allows to examine the effect of different factors or potential therapies on tumor progression.

implantation-evaluation-melanoma-murine-choroid-via-optical-coherence

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Cancer Research

1.5K vues.  Kaplan Medical Center. Établir des tumeurs comme la partie postérieure de l’œil est difficile. Cette méthode permet l’induction de tumeurs reproductibles du mélanome choroïdien chez la souris et l’imagerie en direct de la croissance tumorale pour évaluation. Ce protocole utilise l’imagerie en direct OCT pour évaluer l’emplacement des tumeurs déjà au moment de l’inoculation des cellules tumorales et pour suivre la croissance tumorale chez les animaux vivants.Le mélanome uvéal est une m...