Name: scleral cross-linking using riboflavin and ultraviolet-a radiation for prevention of axial myopia in a rabbit model
Uploaded: 2016-04-03T14:00:00
Description: Watch this Scientific Journal Video about Scleral Cross-linking Using Riboflavin and Ultraviolet-A Radiation for Prevention of Axial Myopia in a Rabbit Model at JoVE.com

The authors are thankful to Ms. Dalia Sela and Mr. Emi Sharon for their professional and excellent technical work in the laboratory.

Animals were treated in accordance with the ARVO resolution on the use of animals in research. The study protocol was approved by the institutional Committee for Laboratory Animal Research (approval no. 022-4598-2; 021211).
1. Preparation for Surgery #1
<ol>
	<li>Weigh and anesthetize a 13 day-old New Zealand white rabbit with an intramuscular injection of ketamine hydrochloride 100 mg/ml (100 mg/kg) and xylazine hydrochloride 25 mg/ml (12.5 mg/kg). Those doses are used due to the length of the surgical procedur...

<ol>
	<li>McBrien, N. A., Gentle, A. <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+the+sclera+in+the+development+and+pathological+complications+of+myopia.">Role of the sclera in the development and pathological complications of myopia.</a> Prog. Retin. Eye Res. 22, 307-338 (2003).</li><li>Saw, S. M., Gazzard, G., Au Eong, K. -. G., Tan, D. T. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Myopia:+attempts+to+arrest+progression.">Myopia: attempts to arrest progression.</a> Br. J. Ophthalmol. 86, 1306-1311 (2002).</li><li>Bullimore, M. A., Jones, L. A., Moeschberger, M. L., Zadnik, K., Payor, R. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+retrospective+study+of+myopia+progression+in+adult+contact+lens+wearers.">A retrospective study of myopia progression in adult contact lens wearers.</a> Invest Ophthalmol Vis Sci. 43, 2110-2113 (2002).</li><li>Rose, K., Smith, W. E., Morgan, I., Mitchell, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+increasing+prevalence+of+myopia:+implications+for+Australia.">The increasing prevalence of myopia: implications for Australia.</a> Clin. Exp. Ophthalmol. 29, 116-120 (2001).</li><li>Saw, S. M., Gazzard, G., Shih-Yen, E. C., Chua, W. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Myopia+and+associated+pathological+complications.">Myopia and associated pathological complications.</a> Ophthal. Physiol. Opt. 25, 381-391 (2005).</li><li>Tano, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pathologic+myopia+-+where+are+we+now.">Pathologic myopia - where are we now.</a> Am. J. Ophthalmol. 134, 645-660 (2002).</li><li>Greene, P. R., Guyton, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Time+course+of+rhesus+lid-suture+myopia.">Time course of rhesus lid-suture myopia.</a> Exp. Eye Res. 42, 529-534 (1986).</li><li>McBrien, N. A., Norton, T. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+development+of+experimental+myopia+and+ocular+component+dimensions+in+monocularly+lid-sutured+tree+shrews+(Tupaia+belangeri).">The development of experimental myopia and ocular component dimensions in monocularly lid-sutured tree shrews (Tupaia belangeri).</a> Vision Res. 32, 843-852 (1992).</li><li>McKanna, J. A., Casagrande, V. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reduced+lens+development+in+lid-suture+myopia.">Reduced lens development in lid-suture myopia.</a> Exp. Eye Res. 26, 715-723 (1978).</li><li>Shapiro, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+visual+deprivation+and+myopia.">Experimental visual deprivation and myopia.</a> Doc. Ophthalmol. Proc. Ser. 28, 193-195 (1981).</li><li>Wiesel, T. N., Raviola, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Increase+in+axial+length+of+the+macaque+monkey+eye+after+corneal+opacification.">Increase in axial length of the macaque monkey eye after corneal opacification.</a> Invest. Ophthalmol. Vis. Sci. 18, 1232-1236 (1979).</li><li>Weiss, A. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Unilateral+high+myopia:+optical+components,+associated+factors+and+visual+outcomes.">Unilateral high myopia: optical components, associated factors and visual outcomes.</a> Br J Ophthalmol. 87, 1025-1031 (2003).</li><li>Mechanic, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Crosslinking+of+collagen+in+a+heritable+disorder+of+connective+tissue:+Ehlers-Danlos+syndrome.">Crosslinking of collagen in a heritable disorder of connective tissue: Ehlers-Danlos syndrome.</a> Biochem. Biophys. Res. Com. 47, 267-272 (1972).</li><li>Curtin, B. J., Iwamoto, T., Renaldo, D. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Normal+and+staphylomatous+sclera+of+high+myopia.+An+electron+microscopic+study.">Normal and staphylomatous sclera of high myopia. An electron microscopic study.</a> Arch. Ophthalmol. 97, 912-915 (1979).</li><li>Liu, K. R., Chen, M. S., Ko, L. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electron+microscopic+studies+of+the+scleral+collagen+fibre+in+excessively+high+myopia.">Electron microscopic studies of the scleral collagen fibre in excessively high myopia.</a> J. Formosan Med. Assoc. 85, 1032-1038 (1986).</li><li>Funata, M., Tokoro, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Scleral+change+in+experimentally+myopic+monkeys.">Scleral change in experimentally myopic monkeys.</a> Graefes Arch. Clin. Exp. Ophthalmol. 228, 174-179 (1990).</li><li>McBrien, N. A., Norton, T. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prevention+of+collagen+cross-linking+increases+form+deprivation+myopia+in+tree+shrew.">Prevention of collagen cross-linking increases form deprivation myopia in tree shrew.</a> Exp. Eye Res. 59, 475-486 (1994).</li><li>Iomdina, E. N., Daragan, V. A., Ilyina, E. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Certain+biomechanical+properties+and+cross+linking+of+the+scleral+shell+of+the+eye+in+progressive+myopia.">Certain biomechanical properties and cross linking of the scleral shell of the eye in progressive myopia.</a> Proceedings of XIVth Congress on Biomechanics. Paris: International Society of Biomechanics. , 616-617 (1993).</li><li>Wollensak, G., Sp&#246;rl, E., Seiler, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Riboflavin+/+ultraviolet-A-induced+collagen+crosslinking+for+the+treatment+of+keratoconus.">Riboflavin / ultraviolet-A-induced collagen crosslinking for the treatment of keratoconus.</a> Am. J. Ophthalmol. 135, 620-627 (2003).</li><li>Wollensak, G., Sp&#246;rl, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Collagencrosslinking+of+human+and+porcine+sclera.">Collagencrosslinking of human and porcine sclera.</a> J. Cataract Refract. Surg. 30, 689-695 (2004).</li><li>Wollensak, G., Iomdina, E., Dittert, D. -. D., Salamatina, O., Stoltenburg, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cross-linking+of+scleral+collagen+in+the+rabbit+using+riboflavin+and+UVA.">Cross-linking of scleral collagen in the rabbit using riboflavin and UVA.</a> Acta Ophthalmol. Scand. 83, 477-482 (2005).</li><li>Wollensak, G., Iomdina, E. <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+biomechanical+properties+of+rabbit+sclera+after+collagen+crosslinking+using+riboflavin+and+ultraviolet+(UVA).">Long-term biomechanical properties of rabbit sclera after collagen crosslinking using riboflavin and ultraviolet (UVA).</a> Acta Ophthalmol. 87, 193-198 (2009).</li><li>Wildsoet, C. F., Norton, T. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Toward+controlling+myopia+progression.">Toward controlling myopia progression.</a> Optom. Vis. Sci. 76, 341-342 (1999).</li><li>Avetisov, E. S., Tarutta, E. P., Iomdina, E. N., Vinetskaya, M. I., Andreyeva, M. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nonsurgical+and+surgical+methods+of+sclera+reinforcement+in+progressive+myopia.">Nonsurgical and surgical methods of sclera reinforcement in progressive myopia.</a> Acta Ophthalmol. Scand. 75, 618-623 (1997).</li><li>Thompson, F. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+simplified+sclera+reinforcement+technique.">A simplified sclera reinforcement technique.</a> Am. J. Ophthalmol. 86, 782-790 (1978).</li><li>Whitmore, W. G., Curtin, B. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Scleral+reinforcement:+two+case+reports.">Scleral reinforcement: two case reports.</a> Ophthalmic Surg. 18, 503-505 (1987).</li><li>Dotan, A., Kremer, I., Livnat, T., Zigler, A., Weinberger, D., Bourla, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Scleral+cross-linking+using+riboflavin+and+ultraviolet-A+radiation+for+prevention+of+progressive+myopia+in+a+rabbit+model.">Scleral cross-linking using riboflavin and ultraviolet-A radiation for prevention of progressive myopia in a rabbit model.</a> Exp Eye Res. 127, 190-195 (2014).</li></ol>

We present the first in vivo study of the prevention of axial myopia in a rabbit model using cross-linking technology with riboflavin and UVA irradiation. Although different laboratory animals can be used in this type of study, we chose rabbits mostly due to the size of the eyes and the need to perform crosslinking on the scleral surface.
We found that exposing the rabbit sclera and suturing the upper and lower eyelids to be challenging procedures. We recommend trimming the lid margin...

Myopia is the most common of the refractive disorders. The prevalence of myopia in the USA and Europe is reported to be around 30%, and in Asian countries it affects up to 60% of the general population1,2. Myopic progression occurs in up to 50% of myopes, usually at a rate of around -0.5 dioptres over a two-year interval3. The health costs imposed by myopia are considerable, including expenses for spectacles, contact lenses and refractive surgery and costs related to the increased health risks of glaucoma, cataract, retinal detachment and visual impairment4-6.
In animal studies of myopia, sight reduction is induced by eyelid suturing7-10, placement of an occluder at a short distance from the eye and corneal tattooing11. However, for artificial myopia to occur in these studies, the occlusion process has to be performed on very young animals, as no sight deprivation experiments carried out on adult specimens have proved successful.
One of the important features of severe myopia is a pathological change of the sclera with progressive thinning of the sclera, probably due to a disturbed feedback mechanism of emmetropization after visual deprivation12 or due to some metabolic disorder of the sclera, such as in Ehlers-Danlos syndrome13. Ultimately, both mechanisms lead to stretching and thinning of the sclera, retina and choroid due to structural abnormalities of the myopic sclera such as a decreased collagen fiber diameter14,15 and disturbances in fibrillogenesis16.
Several studies have shown that impaired collagen crosslinking is an important factor in the weakening process of the myopic sclera17-18. Wollensak et al.19-21 induced collagen crosslinking by applying the photosensitizer riboflavin and ultraviolet-A (UVA) irradiation (370 nm) and noted a significant, 157% increase in the rigidity of porcine and human sclera in vitro19 and a 465% increase in rabbit scleral rigidity in vivo (Young&#39;s modulus)20. Crosslinking also had a long-term effect on rabbit sclera in vivo: rigidity increased by 320.4% after 3 days, 277.6% after 4 months, and 502% after 8 months (Young&#39;s modulus)22.
Therapeutic attempts to arrest myopic progression have been published23-26 but the success of these methods is controversial. No efficient means of preventing progressive myopia has been found to date.
The etiology of myopia is still controversial, and its treatment poses a challenge. On the basis of these findings, it is hypothesized that scleral crosslinking can serve as a means for sclera-based treatment of myopic progression. The purpose of this study is to examine the scleral collagen crosslinking effect on the development of axial myopia induced by visual axis occlusion.

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			<td height="42" style="height:42px;width:244px;">0.1% dextran-free riboflavin-5-phosphate 1mg:1ml</td>
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			<td style="width:119px;">D2-5025</td>
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scleral cross-linking using riboflavin and ultraviolet-a radiation for prevention of axial myopia in a rabbit model

Myopic individuals, especially those with severe myopia, are at higher-than-normal risk of cataract, glaucoma, retinal detachment and chorioretinal abnormalities. In addition, pathological myopia is a common irreversible cause of visual impairment and blindness1-3. Our study demonstrates the effect of scleral crosslinking using riboflavin and ultraviolet-A radiation on the development of axial myopia in a rabbit model. The axial length of the eyeball was measured by A-scan ultrasound in New Zealand white rabbits aged 13 days (male and female). The eye then underwent 360&#176; conjunctival peritomy with scleral crosslinking, followed by tarsorrhaphy. Axial elongation was induced in 13 day-old New Zealand rabbits by suturing their right eye eyelids (tarsorrhaphy). The eyes were divided into quadrants, and every quadrant had two scleral irradiation zones, each with an area of 0.2 cm&#178; and a radius of 4 mm. Crosslinking was performed by dropping 0.1% dextran-free riboflavin-5-phosphate onto the irradiation zones 20 sec before ultraviolet-A irradiation and every 20 sec during the 200 sec irradiation time. UVA radiation (370 nm) was applied perpendicular to the sclera at 57 mW/cm&#178; (total UVA light dose, 57 J/cm&#178;). Tarsorrhaphies were removed on day 55, followed by repeated axial length measurements. This study demonstrates that scleral crosslinking with riboflavin and ultraviolet-A radiation effectively prevents occlusion-induced axial elongation in a rabbit model.

Figures 1 and 2 graphically demonstrate the axial length measurements of two groups. Group 1 rabbits underwent scleral crosslinking and tarsorrhaphy on the right eye while the left eye was not operated on (Figure 1). Group 2 rabbits underwent only peritomy and tarsorrhaphy on the right eye while the left eye was not operated on (Figure 2).
In group 1, which unde...

Watch this Scientific Journal Video about Scleral Cross-linking Using Riboflavin and Ultraviolet-A Radiation for Prevention of Axial Myopia in a Rabbit Model at JoVE.com

Scleral Cross-linking Using Riboflavin and Ultraviolet-A Radiation for Prevention of Axial Myopia in a Rabbit Model

We demonstrate the effect of scleral crosslinking with riboflavin and UVA on an axial elongation rabbit eye. Axial elongation was induced in 13 day-old New Zealand rabbits (male and female) by suturing their right eye eyelids (tarsorrhaphy).

Myopic individuals, especially those with severe myopia, are at higher-than-normal risk of cataract, glaucoma, retinal detachment and chorioretinal ...

The overall goal of this procedure is to observe the effects of scleral cross-linking using riboflavin and ultraviolet-A radiation to induce axial myopia in a rabbit model. This method can help answer key questions in the scleral cross-linking field, such as, how can UVA radiation be directed to specific scleral areas. The main advantage of this technique is that it uses UVA radiation, fiber optics, and surgery to reach sceral areas of interest.Assisting the surgical procedure will be Orly Gal-Or, a resident in Rabin Medical Center Ophthalmology Department. Before beginning the procedure, confirm a lack of response to pain reflex and use a sterile cotton swab to apply a small amount of ophthalmic ointment to the non-operated eye. Then, apply topical anesthesia to each eye.And placing the probe perpendicular to the central cornea, use an Ultrasound A scanner to perform three axial length measurements of the eyes. Next, under an ophthalmic operating microscope, use surgical ophthalmic forceps and scissors to make a 360-degree conjunctival peritomy. Use a muscle hook to locate the four extraocular rectus muscles.Then, isolate the muscles with two zero braided silk non-needle sutures to create four quadrants. Using a skin marker, designate one irradiation zone at the equatorial sclera, and one irradiation zone at the posterior sclera in each quadrant. Then, load a three-to five-milliliter syringe with 0.1 percent dextran-free riboflavin 5 phosphate photo-sensitizer solution and attach a 26 gauge lacrimal cannula.Now, turn on an irradiation device with a 370 nanometer UVA light source connected to a beveled down custom made fiber optic, and set the device to 57 milliwatts per square centimeter. Twenty seconds before beginning the irradiation, move the eyeball by pulling the silk sutures in the opposite direction of the quadrant to be treated, and apply photo-sensitizer solution onto the irradiation zone. Then, use the custom made fiber optic to irradiate the selected zone for 200 seconds, applying photo-sensitizer solution to the zone every 20 seconds.After all four quadrants have been irradiated, trim the lid margins with scissors. Then, use four zero ivory colored braided silk to gently suture the upper and lower eyelids. Apply a small amount of ophthalmic ointment onto the lid margin, and place the rabbit under a heat lamp.When the animal is fully recovered, place it into a clean cage with new bedding. Fifty-five days after the cross-linking, use surgical ophthalmic scissors to remove the tarsorrhaphy. Then, perform three axial length measurements on each eye as just demonstrated.In animals that underwent scleral cross-linking and tarsorrhaphy, the mean axial length decreased after eyelid suture, compared to the unoperated eye. In animals that underwent only peritomy and tarsorrhaphy, however, the mean axial length increased in the experimental eye. Indeed, eyes that underwent scleral cross-linking exhibited a lower axial length increase overall, compared to eyes that were peritomized only.While the between-group difference in the mean axial length of the eyes that did not undergo surgery was not statistically significant. While attempting this procedure, it's important to remember to prepare all the necessary equipment in advance. After its development, this technique paved the way for researchers in the field of myopia, who explored the effects of riboflavin and UVA radiation on the retina, choroid, and sclera.After watching this video, you should have a good understanding of how to visualize specific scleral areas of interest, and to apply focused UVA radiation treatments. Don't forget that performing surgeries on such small eyes with delicate rectus muscles can be extremely challenging and that the learning curve for perfecting the technique should be accepted. The implications of this technique extend towards the prevention of pathological myopic complications.Though this method can provide insight into the prevention of axial myopia, it can also be applied to other conditions such as thin scleral areas.

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In vivo Bioluminescence Imaging of Tumor Hypoxia Dynamics of Breast Cancer Brain Metastasis in a Mouse Model

It is well recognized that tumor hypoxia plays an important role in promoting malignant progression and affecting therapeutic response negatively. There is little knowledge about in situ, in vivo, tumor hypoxia during intracranial development of malignant brain tumors because of lack of efficient means to monitor it in these deep-seated orthotopic tumors. Bioluminescence imaging (BLI), based on the detection of light emitted by living cells expressing a luciferase gene, has been rapidly adopted for cancer research, in particular, to evaluate tumor growth or tumor size changes in response to treatment in preclinical animal studies. Moreover, by expressing a reporter gene under the control of a promoter sequence, the specific gene expression can be monitored non-invasively by BLI. Under hypoxic stress, signaling responses are mediated mainly via the hypoxia inducible factor-1&alpha; (HIF-1&alpha;) to drive transcription of various genes. Therefore, we have used a HIF-1&alpha; reporter construct, 5HRE-ODD-luc, stably transfected into human breast cancer MDA-MB231 cells (MDA-MB231/5HRE-ODD-luc). In vitro HIF-1&alpha; bioluminescence assay is performed by incubating the transfected cells in a hypoxic chamber (0.1% O2) for 24 hr before BLI, while the cells in normoxia (21% O2) serve as a control. Significantly higher photon flux observed for the cells under hypoxia suggests an increased HIF-1&alpha; binding to its promoter (HRE elements), as compared to those in normoxia. Cells are injected directly into the mouse brain to establish a breast cancer brain metastasis model. In vivo bioluminescence imaging of tumor hypoxia dynamics is initiated 2 wks after implantation and repeated once a week. BLI reveals increasing light signals from the brain as the tumor progresses, indicating increased intracranial tumor hypoxia. Histological and immunohistochemical studies are used to confirm the in vivo imaging results. Here, we will introduce approaches of in vitro HIF-1&alpha; bioluminescence assay, surgical establishment of a breast cancer brain metastasis in a nude mouse and application of in vivo bioluminescence imaging to monitor intracranial tumor hypoxia.

In vivo Bioluminescence Imaging of Tumor Hypoxia Dynamics of Breast Cancer Brain Metastasis in a Mouse Model

Bioluminescence imaging of hypoxia inducible factor-1&alpha; activity is applied to monitor intracranial tumor hypoxia development in a breast cancer brain metastasis mouse model.

It is well recognized that tumor hypoxia plays an important role in promoting malignant progression and affecting therapeutic response negatively. There ...

Stereotactic Intracranial Implantation and In vivo Bioluminescent Imaging of Tumor Xenografts in a Mouse Model System of Glioblastoma Multiforme

Glioblastoma multiforme (GBM) is a high-grade primary brain cancer with a median survival of only 14.6 months in humans despite standard tri-modality treatment consisting of surgical resection, post-operative radiation therapy and temozolomide chemotherapy 1. New therapeutic approaches are clearly needed to improve patient survival and quality of life. The development of more effective treatment strategies would be aided by animal models of GBM that recapitulate human disease yet allow serial imaging to monitor tumor growth and treatment response. In this paper, we describe our technique for the precise stereotactic implantation of bio-imageable GBM cancer cells into the brains of nude mice resulting in tumor xenografts that recapitulate key clinical features of GBM 2. This method yields tumors that are reproducible and are located in precise anatomic locations while allowing in vivo bioluminescent imaging to serially monitor intracranial xenograft growth and response to treatments 3-5. This method is also well-tolerated by the animals with low perioperative morbidity and mortality.

Stereotactic Intracranial Implantation and In vivo Bioluminescent Imaging of Tumor Xenografts in a Mouse Model System of Glioblastoma Multiforme

We describe an integrated method for the precise, stereotactic implantation of human glioblastoma multiforme cells into the brains of nude mice and subsequent serial in vivo imaging to monitor growth and response to treatment of the resultant xenografts.

Glioblastoma multiforme (GBM) is a high-grade primary brain cancer with a median survival of only 14.6 months in humans despite standard tri-modality ...

Matrix-assisted Autologous Chondrocyte Transplantation for Remodeling and Repair of Chondral Defects in a Rabbit Model

Articular cartilage defects are considered a major health problem because articular cartilage has a limited capacity for self-regeneration 1. Untreated cartilage lesions lead to ongoing pain, negatively affect the quality of life and predispose for osteoarthritis. During the last decades, several surgical techniques have been developed to treat such lesions. However, until now it was not possible to achieve a full repair in terms of covering the defect with hyaline articular cartilage or of providing satisfactory long-term recovery 2-4. Therefore, articular cartilage injuries remain a prime target for regenerative techniques such as Tissue Engineering. In contrast to other surgical techniques, which often lead to the formation of fibrous or fibrocartilaginous tissue, Tissue Engineering aims at fully restoring the complex structure and properties of the original articular cartilage by using the chondrogenic potential of transplanted cells. Recent developments opened up promising possibilities for regenerative cartilage therapies.
The first cell based approach for the treatment of full-thickness cartilage or osteochondral lesions was performed in 1994 by Lars Peterson and Mats Brittberg who pioneered clinical autologous chondrocyte implantation (ACI) 5. Today, the technique is clinically well-established for the treatment of large hyaline cartilage defects of the knee, maintaining good clinical results even 10 to 20 years after implantation 6. In recent years, the implantation of autologous chondrocytes underwent a rapid progression. The use of an artificial three-dimensional collagen-matrix on which cells are subsequently replanted became more and more popular 7-9.
MACT comprises of two surgical procedures: First, in order to collect chondrocytes, a cartilage biopsy needs to be performed from a non weight-bearing cartilage area of the knee joint. Then, chondrocytes are being extracted, purified and expanded to a sufficient cell number in vitro. Chondrocytes are then seeded onto a three-dimensional matrix and can subsequently be re-implanted. When preparing a tissue-engineered implant, proliferation rate and differentiation capacity are crucial for a successful tissue regeneration 10. The use of a three-dimensional matrix as a cell carrier is thought to support these cellular characteristics 11.
The following protocol will summarize and demonstrate a technique for the isolation of chondrocytes from cartilage biopsies, their proliferation in vitro and their seeding onto a 3D-matrix (Chondro-Gide, Geistlich Biomaterials, Wollhusen, Switzerland). Finally, the implantation of the cell-matrix-constructs into artificially created chondral defects of a rabbit's knee joint will be described. This technique can be used as an experimental setting for further experiments of cartilage repair.

An experimental technique for the treatment of chondral defects in the rabbit's knee joint is described. The implantation of autologous chondrocytes seeded on a matrix is a well-accepted method for the remodeling and repair of articular cartilage lesions providing satisfying long-term results. Matrix-assisted autologous chondrocyte transplantation (MACT) offers a standardized and clinically established implantation method.

Articular cartilage defects are considered a major health problem because articular cartilage has a limited capacity for self-regeneration 1. Untreated ...

Screening for Melanoma Modifiers using a Zebrafish Autochthonous Tumor Model

Genomic studies of human cancers have yielded a wealth of information about genes that are altered in tumors1,2,3. A challenge arising from these studies is that many genes are altered, and it can be difficult to distinguish genetic alterations that drove tumorigenesis from that those arose incidentally during transformation. To draw this distinction it is beneficial to have an assay that can quantitatively measure the effect of an altered gene on tumor initiation and other processes that enable tumors to persist and disseminate. Here we present a rapid means to screen large numbers of candidate melanoma modifiers in zebrafish using an autochthonous tumor model4 that encompasses steps required for melanoma initiation and maintenance. A key reagent in this assay is the miniCoopR vector, which couples a wild-type copy of the mitfa melanocyte specification factor to a Gateway recombination cassette into which candidate melanoma genes can be recombined5. The miniCoopR vector has a mitfa rescuing minigene which contains the promoter, open reading frame and 3'-untranslated region of the wild-type mitfa gene. It allows us to make constructs using full-length open reading frames of candidate melanoma modifiers. These individual clones can then be injected into single cell Tg(mitfa:BRAFV600E);p53(lf);mitfa(lf)zebrafish embryos. The miniCoopR vector gets integrated by Tol2-mediated transgenesis6 and rescues melanocytes. Because they are physically coupled to the mitfa rescuing minigene, candidate genes are expressed in rescued melanocytes, some of which will transform and develop into tumors. The effect of a candidate gene on melanoma initiation and melanoma cell properties can be measured using melanoma-free survival curves, invasion assays, antibody staining and transplantation assays.

A rapid way to screen for melanoma modifiers using a zebrafish autochthonous tumor model is presented. It takes advantage of the miniCoopR vector which allows for expression of candidate melanoma genes in melanocytes. A method to obtain melanoma-free survival curves, an invasion assay, a protocol for antibody staining of scale melanocytes and a melanoma transplantation assay are described.

Genomic studies of  human cancers have yielded a wealth of information about genes that are altered  in tumors1,2,3. A challenge arising from these ...

The In ovo CAM-assay as a Xenograft Model for Sarcoma

Sarcoma is a very rare disease that is heterogeneous in nature, all hampering the development of new therapies. Sarcoma patients are ideal candidates for personalized medicine after stratification, explaining the current interest in developing a reproducible and low-cost xenotransplant model for this disease. The chick chorioallantoic membrane is a natural immunodeficient host capable of sustaining grafted tissues and cells without species-specific restrictions. In addition, it is easily accessed, manipulated and imaged using optical and fluorescence stereomicroscopy. Histology further allows detailed analysis of heterotypic cellular interactions.
This protocol describes in detail the in ovo grafting of the chorioallantoic membrane with fresh sarcoma-derived tumor tissues, their single cell suspensions, and permanent and transient fluorescently labeled established sarcoma cell lines (Saos-2 and SW1353). The chick survival rates are up to 75%. The model is used to study graft- (viability, Ki67 proliferation index, necrosis, infiltration) and host (fibroblast infiltration, vascular ingrowth) behavior. For localized grafting of single cell suspensions, ECM gel provides significant advantages over inert containment materials. The Ki67 proliferation index is related to the distance of the cells from the surface of the CAM and the duration of application on the CAM, the latter determining a time frame for the addition of therapeutic products.

The In ovo CAM-assay as a Xenograft Model for Sarcoma

The in ovo chorioallantoic membrane (CAM) is grafted with fresh sarcoma-derived tumor tissues, their single cell suspensions, and permanent and transient fluorescently labeled established sarcoma cell lines. The model is used to study graft- (viability, Ki67 proliferation index, necrosis, infiltration) and host (fibroblast infiltration, vascular ingrowth) behavior.

Sarcoma is a very rare disease that is heterogeneous in nature, all hampering the development of new therapies. Sarcoma patients are ideal candidates for ...

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

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

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

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

Second Harmonic Generation Signals in Rabbit Sclera As a Tool for Evaluation of Therapeutic Tissue Cross-linking (TXL) for Myopia

Methods to strengthen tissue by introducing chemical bonds (non-enzymatic cross-linking) into structural proteins (fibrillar collagens) for therapy include photochemical cross-linking and tissue cross-linking (TXL) methods. Such methods for inducing mechanical tissue property changes are being employed to the cornea in corneal thinning (mechanically weakened) disorders such as keratoconus as well as the sclera in progressive myopia, where thinning and weakening of the posterior sclera occurs and likely contributes to axial elongation. The primary target proteins for such tissue strengthening are fibrillar collagens which constitute the great majority of dry weight proteins in the cornea and sclera. Fortuitously, fibrillar collagens are the main source of second harmonic generation signals in the tissue extracellular space. Therefore, modifications of the collagen proteins, such as those induced through cross-linking therapies, could potentially be detected and quantitated through the use of second harmonic generation microscopy (SHGM). Monitoring SHGM signals through the use of a laser scanning microscopy system coupled with an infrared excitation light source is an exciting modern imaging method that is enjoying widespread usage in the biomedical sciences. Thus, the present study was undertaken in order to evaluate the use of SHGM microscopy as a means to measure induced cross-linking effects in ex vivo rabbit sclera, following an injection of a chemical cross-linking agent into the sub-Tenon&#39;s space (sT), an injection approach that is standard practice for causing ocular anesthesia during ophthalmologic clinical procedures. The chemical cross-linking agent, sodium hydroxymethylglycinate (SMG), is from a class of cosmetic preservatives known as formaldehyde releasing agents (FARs). Scleral changes following reaction with SMG resulted in increases in SHG signals and correlated with shifts in thermal denaturation temperature, a standard method for evaluating induced tissue cross-linking effects.

Second Harmonic Generation Signals in Rabbit Sclera As a Tool for Evaluation of Therapeutic Tissue Cross-linking TXL for Myopia

This protocol describes techniques for evaluating chemical cross-linking of the rabbit sclera using&#160;second harmonic generation imaging and differential scanning calorimetry.

Methods to strengthen tissue by introducing chemical bonds (non-enzymatic cross-linking) into structural proteins (fibrillar collagens) for therapy ...

Isometric Contractility Measurement of the Mouse Mesenteric Artery Using Wire Myography

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and drugs. It is widely used in many studies on the physiological functions of vascular smooth muscle, the pathogenesis of vascular diseases such as hypertension, and the development of smooth muscle relaxant drugs. The mouse is a widely used model animal with a large pool of disease models and genetically modified strains. We introduced this method to measure the isometric contraction of mouse mesenteric artery in detail. A 1.4-mm segment of mouse mesenteric resistance artery was isolated and mounted on a myograph chamber by passing two steel wires through its lumen. After equilibration and normalization steps, the vessel segment was potentiated by a high-K+ solution twice prior to the contraction assay. As an example of the application of this method in drug development, we measured the relaxant effect of a novel natural substance, neoliensinine, isolated from a Chinese herb, embryos of the lotus seed (Nelumbo nucifera Gaertn.) on mouse mesenteric arteries. The vessel segments mounted on the myograph chamber were stimulated with a high-K+ solution. When the force tension reached a stable sustained phase, cumulative doses of neoliensinine were added to the chamber. We found that neoliensinine had a dose-dependent relaxant effect on smooth muscle contraction, thus suggesting that it bears potential activity against hypertension. In addition, as the vessel segment can survive at least 4 hours after mounting and maintain contractility induced by the high-K+ solution for many times, we suggest that the wire myograph system may be used for the time-consuming process of drug screening.

The wire myograph technique is used to investigate vascular smooth muscle functions and screen new drugs. We report a detailed protocol for measuring the isometric contractility of the mouse mesenteric artery and for screening new relaxants of vascular smooth muscle.

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and ...

Targeted and Selective Treatment of Pluripotent Stem Cell-derived Teratomas Using External Beam Radiation in a Small-animal Model

The growing number of victims of &#34;stem cell tourism,&#34; the unregulated transplantation of stem cells worldwide, has raised concerns about the safety of stem cell transplantation. Although the transplantation of differentiated rather than undifferentiated cells is common practice, teratomas can still arise from the presence of residual undifferentiated stem cells at the time of transplant or from spontaneous mutations in differentiated cells. Because stem cell therapies are often delivered into anatomically sensitive sites, even small tumors can be clinically devastating, resulting in blindness, paralysis, cognitive abnormalities, and cardiovascular dysfunction. Surgical access to these sites may also be limited, leaving patients with few therapeutic options. Controlling stem cell misbehavior is, therefore, critical for the clinical translation of stem cell therapy.
External beam radiation offers an effective means of delivering targeted therapy to decrease the teratoma burden while minimizing injury to surrounding organs. Additionally, this method avoids genetic manipulation or viral transduction of stem cells-which are associated with additional clinical safety and efficacy concerns. Here, we describe a protocol to create pluripotent stem cell-derived teratomas in mice and to apply external beam radiation therapy to selectively ablate these tumors in vivo.

Research on treatment strategies for pluripotent stem cell-derived teratomas is important for the clinical translation of stem cell therapy. Here, we describe a protocol to, first, generate stem cell-derived teratomas in mice and, then, to selectively target and treat these tumors in vivo using a small-animal irradiator.

The growing number of victims of &#34;stem cell tourism,&#34; the unregulated transplantation of stem cells worldwide, has raised concerns about the ...

Transthoracic Echocardiographic Examination in the Rabbit Model

Large animal models such as the rabbit are valuable for translational preclinical research. Rabbits have a similar cardiac electrophysiology compared to that of humans and that of other large animal models such as dogs and pigs. However, the rabbit model has the additional advantage of lower maintenance costs compared to other large animal models. The longitudinal evaluation of cardiac function using echocardiography, when appropriately implemented, is a useful methodology for preclinical assessment of novel therapies for heart failure with reduced ejection fraction (e.g. cardiac regeneration). The correct use of this non-invasive tool requires the implementation of a standardized examination protocol following international guidelines. Here we describe, step by step, a detailed protocol supervised by veterinary cardiologists for performing echocardiography in the rabbit model, and demonstrate how to correctly obtain the different echocardiographic views and imaging planes, as well as the different imaging modes available in a clinical echocardiography system routinely used in human and veterinary patients.

Here we describe, step by step, a detailed protocol for performing echocardiography in the rabbit model. We show how to correctly obtain the different echocardiographic views and imaging planes, as well as the different imaging modes available in a clinical echocardiography system routinely used in human and veterinary patients.

Large animal models such as the rabbit are valuable for translational preclinical research. Rabbits have a similar cardiac electrophysiology compared to ...