TRANSGENIC NEURAL PLATE CONTRIBUTES NEURONAL CELLS THAT SURVIVE GREATER-THAN ONE-YEAR WHEN TRANSPLANTED INTO THE ADULT-MOUSE CENTRAL-NERVOUS-SYSTEM

Neural plate cells from the early embryo may have a number of importan t advantages as donor material for the delivery of foreign genes into the diseased adult central nervous system (CNS). Mesencephalic neural plate from transgenic GT4-2 mice was used as a source of marked donor cells to determine whether transgene expressing embryonic CNS progenit or cells can be used as donor material for implantation into the adult mouse brain. Transgenic mouse embryos from this line express the Esch erichia coil beta-galactosidase (beta-gal) gene throughout early CNS d evelopment. At the early somite stage (Embryonic Day 8.5), mesencephal ic neural plate tissue from heterozygous embryos was dissected out and either transferred into culture for characterization or immediately i mplanted into the striatum or lateral ventricle of adult wild-type CD- 1 mice. Explants of neural plate tissue possessed intense beta-gal act ivity and produced extensive outgrowth of neurofilament-positive proce sses after 6 days in vitro. Many beta-gal-positive cells migrated away from the explanted tissue mass. Grafts of transgenic neural plate tis sue in the normal adult mouse striatum, sampled 2 weeks to 1 year afte r implantation, possessed healthy beta-gal-positive cells. More detail ed analysis of grafts 3 months after implantation indicated that most beta-gal-positive cells were also immunoreactive for neurofilament and microtubule-associated proteins, two neuron-specific markers. In addi tion, extensive neurofilament-positive axonal tangles were evident wit hin the grafts among the beta-gal-positive cells. Electron microscopic (ERI) findings of implanted tissue stained with Blue-Gal revealed man y beta-gal-positive neurons received synaptic contacts from other cell s. A few donor-derived astrocytes were also found in the grafts by EM analysis. No obvious signs of immunological rejection, or of significa nt decrease in graft volume, were observed at any age. Some beta-gal-p ositive cells were observed to lie up to 230 mu m away from the main g raft mass in both striatal and intraventricular implantations. These d ata suggest that the neural plate can contribute a long-surviving popu lation of neuronal and astrocytic cells when transplanted into the adu lt CNS. (C) 1995 Academic Press, Inc.