Human Fetal Astrocytes as anEx VivoGene Therapy Vehicle for Delivering Biologically Active Nerve Growth Factor

Abstract

The therapeutic use of neurotrophic factors for neurodegenerative diseases is promising, however, optimal methods for continuous delivery of these substances to the human central nervous system (CNS) remains problematic. One approach would be to graft genetically engineered human cells that continuously secrete high levels of a biologically produced and processed neurotrophic factor. This ex vivo gene therapy approach has worked well in animal models of neurodegenerative diseases using a variety of nonneuronal cell types to deliver the transgene. In our studies, we have been investigating the potential of astrocytes, a cell type normally present in the CNS, as a vehicle for ex vivo gene therapy. Here, we demonstrate that astrocytes in the human fetal cortex can be isolated and efficiently infected with an amphotropic retrovirus harboring mouse beta-nerve growth factor (NGF). These transduced astrocytes express high levels of NGF mRNA and secrete bioactive NGF protein as demonstrated by stimulation of neurite outgrowth from adrenal chromaffin cells. NGF ELISA showed that these astrocytes secrete NGF protein at a rate of 41 ng/day per 10(5) cells after 2 weeks in vitro, whereas NGF is undetectable in medium conditioned by normal astrocytes. These data suggest that human fetal astrocytes can be used for delivering biologically produced neurotrophic factors to the human CNS.

Primary astrocytes retrovirally transduced with a tyrosine hydroxylase transgene driven by a glial-specific promoter elicit behavioral recovery in experimental Parkinsonism

“…Recently, the preparation of both fetal and adult engineered human astrocytes has been reported (Lin et al, 1997;Ridet et al, 1999), as well as the grafting of adult rat astrocytes expressing a reporter gene (Ljumberg et al, 1999). These results, together with the use of glial-specific promoters, further advocate the use of astrocytes for the delivery of neuroactive substances into the CNS, and of its possible application in human gene therapy.…”

Syngeneic central nervous system transplantation of genetically transduced mature, adult astrocytes

“…Fetal tissue grafts and cells derived from fetal nervous tissue have been utilized for this purpose. 5,6 However, the widespread use of fetal-derived tissues in human studies is problematic due to ethical considerations and legislative regulations 7,8 and relative concerns regarding allogeneic transplantation and widespread dissemination throughout the CNS. Other cell sources have included CNS progenitor cells [9][10][11][12] and immortalized derived cell lines.…”

Transplantation of human adult astrocytes: Efficiency and safety requirements for an autologous gene therapy

“…Their characteristics as efficient cellular "minipumps" and neuronal supportive substrate (Ridet et al, 1997;Ridet and Privat, 1999) make them promising tools to deliver therapeutic molecules into the brain. Many studies have demonstrated that astrocytes from different sources can be transplanted successfully into the CNS after genetic modification (Cunningham et al, 1994;Yoshimoto et al, 1995;Lundberg et al, 1996;Keir et al, 1997;Lin et al, 1997;Ljungberg et al, 1999;Cortez et al, 2000;Ericson et al, 2002).…”