Differentiation and maturation of rabbit retinal oligodendrocyte precursor cells in vitro

The differentiation of oligodendrocytes from undifferentiated progenitor cells was studied in cultures obtained from the postnatal rabbit retina. 'Sandwich' cultures were established by turning the coverslips with adhering cells up-side down about 24 h after seeding. As a result O4-positive oligodendrocyte progenitors stop dividing and differentiate. Within 6 days in vitro they form extensive membranous sheets and acquire myelin associated glycoprotein (MAG), proteolipid protein (PLP), and myelin basic protein (MBP). O4-/MBP-positive oligodendrocytes and vimentin-positive/GFAP-negative Müller cells (a kind of modified astrocyte type in the retina), which are also present in these cultures, occupy distinct territories in vitro. When oligodendrocyte precursors were seeded onto a preformed Müller cell feeder layer they prefer to settle on the Müller cell free substrate poly-L-lysine, develop numerous processes but no membranous sheets and fail to acquire detectable amounts of MBP. In addition, culturing Müller cells and oligodendrocytes within the same medium, but without direct contact to each other, oligodendrocyte precursor cells fail to express MBP. The Müller cell factor(s) responsible for this interaction remains to be determined.