Cell aggregate including retinal tissue and production method therefor

#The present invention relates to a sphere-like cell aggregate containing neural retina and a method for producing the same. In particular, the present invention relates to a sphere-like cell aggregate comprising a core part containing neural retina and a covering part continuously or discontinuously covering at least a portion of the surface of the core part and containing retinal pigment epithelial cells, and a method for producing the same.

#In instances where photoreceptor cells and retinal pigment epithelial (RPE) cells are simultaneously impaired, such as advanced age-related macular degeneration, simultaneous transplantation of neural retina (NR) and retinal pigment epithelial (RPE) cells is considered desirable.

#In connection with retinal transplantation therapy for diseases based on retinal tissue disorders such as retinal pigment degeneration, researches on methods for producing neural retina and retinal pigment epithelial (RPE) cells from pluripotent stem cells have been actively conducted. As a method for producing neural retina from pluripotent stem cells, for example, a method for obtaining neural retina by subjecting an aggregate of pluripotent stem cells to suspension culture in a culture medium containing a BMP signaling pathway agonist is known (Patent Literatures 1 and 2 and Non Patent Literature 1). Furthermore, as a method for producing RPE cells from pluripotent stem cells, a method for obtaining RPE cells from retinal progenitor cells induced, for example, in a culture medium containing a retinoic acid receptor antagonist is known (Patent Literature 3). However, a method for producing a retinal tissue containing both NR and RPE cells in a state where both NR and RPE cells are correctly localized in a directional manner as in a retinal tissue in vivo is not known.

#FIG. 1 is diagrams showing microscopic observation results (A, B, C, D) and fluorescence microscopic observation results (A′, B′, C′, D′) of separately prepared retinal pigment epithelial (RPE) cells and neural retina (NR) which were differentiated from human ES cells.

#FIG. 2 is diagrams showing the method of adhering NR and RPE cells of Example 2 (A), and microscopic observation results (B, C, D) and fluorescence microscopic observation results (B′, C′, D′) at 1 hour after adhesion and next day of adhesion.

#FIG. 3 is diagrams showing the results of observing changes over time at days 1, 6, and 45 after adhesion of NR and RPE cells in Example 2 with a microscope (E, F, G), and the results of observing morphology of RPE cells adhering to the NR surface at day 45 with a microscope (H) and with a fluorescence microscope (H′).

#[Sphere-Like Cell Aggregate]

#A sphere-like cell aggregate according to one embodiment of the present invention comprises a core part containing neural retina and a covering part continuously or discontinuously covering at least a portion of the surface of the core part, and has the following features (1) to (4):

#(1) in the neural retina, a neural retinal layer including at least a photoreceptor layer is formed, wherein the photoreceptor layer contains one or more types of cells selected from the group consisting of at least a photoreceptor cell, a photoreceptor progenitor cell, and a retinal progenitor cell, and the cells contained in the photoreceptor layer are continuously present in a tangential direction to the surface of the core part; (2) the covering part includes retinal pigment epithelial cells in contact with each other; (3) the cell aggregate is free of a crystalline lens, a vitreous, a cornea, and a blood vessel; and (4) the retinal pigment epithelial cells do not constitute an epithelial structure continued with the neural retinal layer.