Assessment of the Chemosensitivity of Uveal Melanoma Cells Ex Vivo.

The study was designed to create a primary cell culture of uveal melanoma and to evaluate its resistance to chemotherapy. Of the obtained 20 samples of uveal melanoma, the primary cultures with proliferation sufficient for MTT test were derived in only 7 cases. However, even these cultures were unable to survive more than 4 passages; the cells accumulated melanin and underwent apoptosis. Retinol palmitate and nepafenac produced no cytotoxic effect on uveal melanoma cells. Of 5 cultures treated with sodium valproate (Convulex), no pronounced cytotoxic effect was observed in one culture (UM4); in 2 cultures, 50% cells died in the presence of the lowest drug concentration of 1.88 mg/ml; and in 2 cultures, the same effect was achieved at drug concentrations 7-10 mg/ml. The cytotoxic effect of treosulfan was evaluated in only 4 cultures of uveal melanoma: the drug exhibited pronounced antitumor activity on all cultures, in 2 cases, it was effective at a concentration of 0.16 mg/ml. Gemcitabine in a concentration of 2.5 mg/ml produced a pronounced cytotoxic effect in 4 out of 7 cultures (death of 70-80% cells) and induced death of ~45% cells in the remaining 3 cultures. Mitoxantrone had ambiguous effect: in 2 of 5 cultures, the drug in high concentrations stimulated the growth of tumor cells, but in 3 cultures, the drug even in minimum concentrations induced death of 70-80% cells.

Development of In Vivo Model of Intraocular Retinoblastoma.

Here we describe creation of a model of intraocular retinoblastoma on 4 mature immunodeficient BALB/c nude mice of both sexes. A suspension of the primary retinoblastoma culture was injected into each of the 8 eyes of the test animals. The injections were performed under the control of an operating microscope using insulin syringes with a diameter of 29G transsclerally into the subretinal space in a volume of 0.3 ml at a rate of 10,000 cells in 25 µl physiological saline. The culture of Rb10 cells derived from a patient with retinoblastoma passed 12 passages at the time of the experiments. After 9-week follow-up, a clinical (ophthalmoscopy) and instrumental (ultrasound) study was performed with visualization of the tumor mass on the fundus. After enucleation, a morphological study was performed. The retinoblastoma tumor nodes were identified in two eyes. The proposed model can be used for further research and for testing new chemotherapeutic drugs and treatment regimens for retinoblastoma.

Retinoblastoma Cell Culturing and Evaluation of Their Drug Resistance.

We obtained primary culture of retinoblastoma cells and evaluated the resistance of cultured ells to chemotherapy. The study included 19 patients aged 6-64 months (mean 27.9±17.4 months); of these, 6 (31.6%) patients with bilateral retinoblastoma and 13 (68.4%) patients with unilateral form. In 18 (94.7%) patients, group E retinoblastoma was diagnosed. Enucleation was performed in all patients; in 94.7% cases, low-differentiated retinoblastoma was identified. Samples of the tumor tissue were taken to derive a cell culture and to study drug resistance and metabolic activity of cells (MTT test). In 4 cases, adhesion primary cultures of retinoblastoma were derived. Cytological verification of the obtained cultures was performed. The primary cultures were derived from 4 of 6 bilateral tumors and from none of 13 unilateral tumors (p=0.003). There were no statistically significant correlations with patient age (p=0.33) and the presence of calcifications in the tumor (p=0.26). MTT test revealed no differences in the sensitivity of cell cultures to irinotecan and ifosfamide. Pronounced differences in the resistance of cell cultures were observed for oxaliplatin and ascorbic acid. MTT test with evaluation of drug resistance can be used both in clinical practice for adjusting chemotherapy regimen and in development of new approaches to the treatment of retinoblastoma with assessment of in vivo tumor cell resistance in animal models.

[Malignant medulloepithelioma mimicking retinoblastoma - clinical and morphological case analysis and cell culture experience]. / . Zlokachestvennaya medulloepitelioma, simuliruyushchaya retinoblastomu ­ kliniko-gistologicheskii analiz sluchaya i opyt polucheniya kletochnoi kul'tury.

The paper presents clinical and morphological case analysis of primary intraocular malignant medulloepitelioma (medulloblastoma) of rare localization (central part of the retina with optic nerve involvement) that simulated retinoblastoma in a 2-year-old child. Histological features of the tumor are given in details (tubular and mesh structures of the tumor, rosettes, ribbons, cells with hyperchromic nuclei, and cellular polymorphism). An experience of creating a primary intraocular malignant medulloepitelioma cell culture, as yet exclusive in the Russian Federation, is described. Culture sensitivity for particular drugs (oxaliplatin, irinotecan, ifosfamide, and ascorbic acid at different concentrations) was evaluated by MTT-assay. Of the four products, IC50 (3.3 mg/ml) was obtained only for ascorbic acid. Despite the relative rarity of primary intraocular malignant medulloepitelioma, its differential diagnosis should be carried out, with retinoblastoma in mind in the first place. The obtained data on the effectiveness of ascorbic acid against intraocular malignant medulloepitelioma cells can be used to supplement the existing chemotherapeutic protocols in pediatric ocular and neuro-oncology.