Ординатура / Офтальмология / Английские материалы / Ocular Oncology_Albert, Polans_2003

and coworkers in 1984 [71]. Several cell lines from primary uveal melanoma [77–81] and metastatic uveal melanoma [81] have been described. Some of these cell lines have been growing for several years without morphological change [81]. It has become apparent that there is no single universal grwoth medium for human uveal melanoma and that a particular cell type may grow well in one medium but not another.

Human uveal melanomas transferred to the eyes of animals are termed orthotopic transplantations, whereas cutaneous melanomas like the Greene or the B16 melanoma transferred to the eye are termed heterotopic transplantations. It is becoming evident that tumors transplanted to heterotopic sites often do not display metastatic behavior consistent with the original tumor. Many tumors do not metastasize from heterotopic sites in nude mice but will form metastases after orthotopic transplantation [82]. For these reasons, orthotopic transplantations of human uveal melanoma constitute an important model. The effect of orthotopic transplantation may be due at least in part to the influence of local organ-specific factors [83].

C.Hamster Model

In 1961, Burns and Fraunfelder described establishment of an ocular melanoma model using suspensions of Greene melanoma cells [84]. Those investigators injected tumor cell suspensions into the AC of Syrian golden hamsters. Tumors grew and extended into the eyelids, orbit, and cranial cavity. Posterior auricular, cervical, and thoracic cage lymph nodes were involved by lymphatic spread. Metastases to lungs, liver, thoracic wall, and diaphragm were observed [84]. Fournier and associates inserted pieces of melanotic Greene melanoma onto the surface of the iris in Syrian golden hamsters [85]. In 1974, Albert and collaborators injected Greene melanoma cells into the choroid of the Syrian hamster [86]. Those investigators found histological evidence of development of choroidal melanomas in most injected eyes. Two weeks after injection, the eyes showed tumor growth and extension through Bruch’s membrane in most instances. Some 3–4 weeks after injection, the tumor within the globe was often necrotic, and perforation of the sclera had occurred, resulting in extensive orbital invasion. Necropsy revealed evidence of extensive metastases by the sixth week [32].

D.Murine Model

1.Murine Model Using Greene Melanoma Cells

In 1966, Greene and Harvey transferred amelanotic Greene melanoma into the AC and brain of a few mice of the DBA or BDF strain and found that the tumor survived the transfer to both transplantation sites [57].

2.Murine Model Using B16 Melanoma Cells

B16 melanoma cell lines have been successfully inoculated into the AC of syngeneic murine eyes (Figs. 6 to 8), resulting in tumor growth and pulmonary metastases [6,50,68,87–89]. Different AC inoculation techniques have been described, including

Figure 8 The AC melanoma shown in Fig. 2 is present in the iris. (H&E, 663.)

Enucleation performed 8 to 12 days after AC inoculation of B16-F10 melanoma cell suspensions and necropsies approximately 4 weeks after inoculation have shown a pulmonary metastatic rate of 0–33% [68,87,88]. B16-F10 cells derived in vivo differ from cultured B16-F10 cells with regard to the metastatic rate to the lung. When B16-F10 cells are passaged five times in culture and inoculated into the AC, a marked decrease in the frequency and extent of metastases, and an increase in survival are observed as compared to inoculation of B16-F10 tumors cells maintained in vivo [64].

Successful inoculation of tissue culture B16 melanoma cells into the posterior compartment (PC) of murine eyes has been described by Grossniklaus and coworkers [87,88,90]. The PC includes the ciliary body, choroid, subretinal space and vitreous. There is evidence that the PC provides a unique immune-privileged environment. The PC model is analogous to human intraocular melanoma, which arises in the choroid and metastasizes hematogenously. B16-F10 melanoma cells inoculated into the PC of C57BL/6 mice were found to metastasize to the lung in 89% of the mice [88]. This higher metastatic rate in the PC compared to the AC model is comparable to the higher metastatic rate of choroidal melanoma compared to iris melanoma. The metastatic rate correlated with tumor vascular pattern and vascular density [90]. One difficulty with the inoculation of melanoma cells into the murine PC was that tumor cells frequently reflux into the subconjunctival space, resulting in subconjunctival melanoma. The primary extraocular tumor growth does not reflect the human situation, in which uveal melanoma is confined to the inside of the eye. A transcorneal inoculation technique that results in intraocular confinement of the inoculated melanoma cells has recently been developed (Figs. 9 and 10) [91]. Hematogenous metastases develop from intraocular melanoma. It appears that extraocular extension of tumor and invasion of conjunctival lymphatics in either the

Figure 9 Continued.

AC or PC model results in lymph node metastasis (Fig. 11). A subculture of the B16 melanoma cell line, the B16-LS9 line, has been developed after repetitive intrasplenic inoculation of B16 melanoma cells and recovery of the cells from the liver [66]. In subsequent experiments, these cells metastasized from the eye to the liver of immune competent mice and there was a positive correlation between the number of pulmonary and liver metastases [65]. B16-LS9 melanoma cells show low MHC class I expression, suggesting that they are susceptible to NK cell-mediated lysis [92]. B16LS9 cells inoculated into the PC of C57BL6 mice, which have been rendered NK celldeficient by treatment with antiasialo GM1, results in a significant increase in hepatic micrometastases and growth of the hepatic micrometastases compared with controls (Fig. 12) [92,93].

3.Murine Model Using Human Uveal Melanoma Cells

Human uveal melanoma cells have been successfully transplanted into the AC of athymic ‘‘nude’’ mice [94]. Albert and coworkers were able to culture human uveal melanoma experimentally in nude mice by transplanting fresh human uveal melanoma into the AC and vitreous [32]. Niederkorn and collaborators inoculated human uveal melanoma cells into the AC of nude Balb/c mice and found tumor growth and liver lesions characterized by necrosis, mild neutrophilic infiltration, and karyorrhexis. Tumor cells in these lesions diffusely stained with a monoclonal antibody that specifically reacted to human nuclear membrane antigens. The authors concluded that human ocular melanoma cells may metastasize to the liver in nude mice but fail to grow progressively [94]. Ma and collaborators found the human

Figure 10 Transcorneal inoculation of B16 melanoma cells shows intrachoroidal melanoma

(*) infiltrating the sclera.

uveal cell line OCM3 to be susceptible to NK cell-mediated cytolysis [95]. These investigators inoculated the OCM3 cell line into the AC of athymic nude mice and in vivo disruption of NK function resulted in the increased severity of metastatic hepatic foci [95]. Injection of human uveal melanoma cells into the PC of beige nude x-linked immune deficient (BNX) mice has been performed (Figs. 13 to 16) [96]. Tumor growth and liver micrometastases were found when different primary and metastatic uveal melanomas were inoculated into the PC of BNX mice [96].

E.Rabbit Model

The rabbit eye is suitable because of its relatively large size, permitting funduscopy and fundus photography, the relatively low cost of procuring and maintaining rabbits compared with other animals with comparably sized eyes, the relatively long life span of the rabbit, and the well-known anatomy and physiology of the rabbit eye [97].