Conditionally immortalized cell lines, engineered to produce and release GABA, modulate the development of behavioral seizures

Transplantation of genetically engineered cells can provide sustained focal delivery of naturally occurring molecules, including neurotransmitters and growth factors. We have engineered immortalized mouse cortical neurons and glia to deliver GABA by driving GAD(65) expression. Engineered cell lines showed GAD(65) mRNA expression, enzymatic activity and GABA release. In vit ro, basal flux of GABA was approximately 20% of total cellular GABA. We tra nsplanted these GABA-producing cells bilaterally into either the anterior o r the posterior substantia nigra of 43 rats. The rats were subsequently kin dled through an electrode placed in the entorhinal cortex. GABA-producing c ells, but not beta-galactosidase-producing cells, affected kindling rates. The number of stimulations needed to reach the first stage-5 seizure and to achieve full kindling differed significantly between the anterior and post erior transplantation sites when GAD(65)-producing cells were transplanted but not when beta-galactosidase-producing cells were transplanted. Our data show that transplanted engineered cells can make and release GABA at physi ologically meaningful concentrations. (C) 2000 Academic Press.