Purpose: The pluripotent embryonic stem cells can differentiate into various kinds of normal tissues. There is no previous report on the differentiation of embryonic stem cell in the intraocular environment. In this paper, the authors tried to investigate the intraocular growth character of mice embryonic stem cells in nude mice.
Methods: Murine embryonic stem cells were cultured and maintained in an undifferentiated state in vitro. They were transplanted into the right eyes of 20 nude mice by microinjection under operating microscope. Animal eye observation, light microscope and immunohistochemical examinations were implemented.
Results: Two to three days after transplantation, small pieces of gray-white material could be viewed in the vitreous cavity. Between the 15th and 20th day, the gray-white mass grew into the anterior chamber in 4 nude mice eyes. Then, the mass at the anterior chamber extended extraocularly. On the 30th day, a remarkable proptosis was observed in two of the four nude mice. In 6 to 45 days, the mice were executed for morphological examination which showed the following typical structures: (1) Undifferentiated cells with prominent nucleolius. (2) Flexner-Wintersteiner-like rosettes. (3) Medulloepithelioma-like structure: the cells were arranged in sheets, cords, tubes, and cysts. (4) Large, spindle-or astrocyte-like cells. (5) Cartilage-like structure. Immunohistochemically, most of the cells were highly positive in NSE staining and a few cells were moderately positive in GFAP staining.
Conclusions: Both animal eye findings and morphologic examinations certificated that the transplanted embryonic stem cells could grow in the eyes of nude mice and differentiate into intraocular medulloepithelioma.