Formation of myelin after transplantation of neural precursor cells into the retina of young postnatal mice

We have isolated neural precursors from the striata of embryonic wildtype a nd transgenic mice ubiquitously expressing enhanced green fluorescent prote in. Cells were expanded in vitro in the presence of epidermal growth factor and transplanted into the retina of young postnatal mice. One month after transplantation, cells showed widespread integration into the host tissue a nd differentiated into a variety of morphologically distinct cell types. A fraction of cells was identified as oligodendrocytes exclusively located in the immediate vicinity to the nerve fiber layer. Similar results were obta ined with neural precursors isolated from embryonic spinal cord. Differenti ated oligodendrocytes and myelin were still detectable in the host tissue 4 months after transplantation, the latest time point investigated. :Remarka bly, prolonged survival periods of experimental animals resulted in a signi ficant increase in the number of donor-derived oligodendrocytes and the are a of the nerve fiber layer being myelinated. The presence of high numbers o f oligodendrocytes and their location close to the retinal nerve fiber laye r suggest that the differentiation of transplanted neural precursors into d istinct neural cell types is influenced by host-derived environmental cues. (C) 2000 Wiley-Liss, Inc.