Neurobiology of Disease (Nov 1994)
Somatic gene transfer to the adult primate central nervous system:in vitroandin vivocharacterization of cells genetically modified to secrete nerve growth factor
Abstract
Somatic gene transfer offers a means of delivering substances to the central nervous system (CNS) in a regionally specific, high-dose, chronic and well-tolerated manner. Studies in rats have shown that genetically modified cell grafts can prevent neuronal degeneration and promote functional recovery after injury and can improve cognitive function in aged subjects. To assess the potential utility of somatic gene transfer techniques in primate models, retroviral vectors were used to modify genetically monkey and human primary skin fibroblasts to produce and secrete human nerve growth factor (NGF).In vitro,all cell types produced NGF and sustained this production through cell growth to confluency, as determined by both Northern blot analysis and ELISA. Adult human fibroblasts produced as much NGF as did young human fibroblasts. Monkey fibroblasts genetically modified to produce NGF were then grafted to intact adult rhesus and cynomolgous monkey brains. Among nine primates that received a total of 76 grafts, surviving cells were found in all subjects up to the maximal experimental timepoint of 6 months. Cholinergic fibres from the host brain penetrated NGF-secreting grafts up to 6 months after grafting, but showed little penetration in control grafts lacking the NGF gene. Autografts survived better than allografts. These findings indicate that both human and primate fibroblasts can be transduced to produce and secrete NGF, can maintain this production whether in a growing or quiescent state and can elicit robust sprouting responses when primate fibroblasts are grafted to the adult brain. Cells genetically modified to produce trophic factors are a useful model for studyingin vitroandin vivoCNS plasticity and for testing potential therapies for neurodegenerative conditions.
