Transplantation of embryonic neuroectodermal progenitor cells into the site of a photochemical lesion: immunohistochemical and electrophysiological analysis
Abstract
GFP labeled/NE-4C neural progenitor cells cloned from primary neuroectodermal cultures of p53- mouse embryos give rise to neurons when exposed to retinoic acid in vitro. To study their survival and differentiation in vivo, cells were transplanted into the cortex of 6-week-old rats, 1 week after the induction of a photochemical lesion or into noninjured cortex.
The electro-physiological properties of GFP/NE-4C cells were studied in vitro (8-10 days after differentiation induction) and 4 weeks after transplantation using the whole-cell patch-clamp technique, and inummohistochemical analyses were carried out. After transplantation into a photochemical lesion, a large number of cells survived, some of which expressed the astrocytic marker GFAP.
GFP/GFAP-posi-tive cells, with an average resting membrane potential (V-rest) of -71.9 mV, displayed passive time- and voltage-independent K currents and, additionally, voltage-dependent A-type K+ currents (K-A) and/or delayed outwardly rectifying K+ currents (K-DR). Numerous GFP-positive cells expressed NeuN, beta III-tubulin, or 68 kD neurofilaments.
GFP/beta III-tubulin-positive cells, with an average V-rest of -61.6 mV, were characterized by the expression of K-A and K-DR currents and tetrodotoxin-sensitive Na+ currents. GFP/NE-4C cells also gave rise to oligodendrocytes, based on the detection of oligodendrocyte-specific markers.
Our results indicate that GFP/NE-4C neural progenitors transplanted into the site of a photochemical lesion give rise to neurons and astrocytes with membrane properties comparable to those transplanted into noninjured cortex. Therefore, GFP/NE-4C cells provide a suitable model for studying neuro- and gliogenesis in vivo.
Further, our results suggest that embryonic neuroectodermal progenitor cells may hold considerable promise for the repair of ischemic brain lesions.