Lentiviral Vectors: A Powerful Tool to Target Astrocytes In Vivo

Abstract

The morphological and functional diversity of astrocytes, and their essential contribution in physiological and pathological conditions, are starting to emerge. However, experimental systems to investigate neuron-glia interactions and develop innovative approaches for the treatment of central nervous system (CNS) disorders are still very limited. Fluorescent reporter genes have been used to visualize populations of astrocytes and produce an atlas of gene expression in the brain. Knock-down or knock-out of astrocytic proteins using transgenesis have also been developed, but these techniques remain complex and time-consuming. Viral vectors have been developed to overexpress or silence genes of interest as they can be used for both in vitro and in vivo studies in adult mammalian species. In most cases, high transduction efficiency and long-term transgene expression are observed in neurons but there is limited expression in astrocytes. Several strategies have been developed to shift the tropism of lentiviral vectors (LV) and allow local and controlled gene expression in glial cells. In this review, we describe how modifications of the interaction between the LV envelope glycoprotein and the surface receptor molecules on target cells, or the integration of cell-specific promoters and miRNA post-transcriptional regulatory elements have been used to selectively express transgenes in astrocytes.

Targeting specific cells in the brain with nanomedicines for CNS therapies

“…Lentiviral vectors (LV) were found to have pseudotype-dependent neuron and glia tropism. Based on such vectors, it is possible to target astrocytes in vivo through modifying LV pseudotype, integrating cell-specific promoters, and using miRNA post-transcriptional regulatory elements [135-137]. However, more studies are needed to take the heterogeneity of astrocytes into consideration, especially when astrocytes are in pathological conditions.…”

Tropism, intracerebral distribution, and transduction efficiency of HIV- and SIV-based lentiviral vectors after injection into the mouse brain: a qualitative and quantitative in vivo study

“…This is in contrast to a number of other studies using VSV-G-pseudotyped HIV-based lentiviral vectors in murine or rat brain, in which a clear prevalence for transduced neurons was observed (e.g., Naldini et al 1996a ; Blömer et al 1997 ; Bensadoun et al 2000 ). However, it has been demonstrated that beside the observed transduction specificity, the choice of the promotor sequence can invoke exclusive expression of the gene of interest in either glial cells or (specific) neurons (Jakobsson et al 2003 ; Delzor et al 2013 ; Schulze et al 2015 ). To avoid this promoter-driven restriction of EGFP expression, we used the strong, ubiquitous SFFV promoter with described activity in neuronal cells (Bender et al 2007 ).…”

“…2 ), which would be in agreement with the EGFP expression data of HIV-1 vectors published previously (Baekelandt et al 2002 ). Diversity in the expression levels might be accounted to differences in promoter activity between these two cell types and/or to disparity in transcription and translation rate among these cells (Stoykova et al 1985 ; Delzor et al 2013 ).…”

“…Tropism of lentiviral vectors to neurons vs. glial cells has been described to depend on their pseudotyping, their transcriptional and post-transcriptional elements used to control transgene expression, the animal species used as a model organism and their developmental stage, the timepoint of observation, the brain areas targeted, and the intracerebral delivery protocol (reviewed by Delzor et al 2013 ). In our experiment, most of these parameters were kept constant including the internal organization of the transfer vectors.…”

Pygmy MicroRNA: Surveillance Cops in Therapy Kingdom

“…As an example, delivered transgene with the binding site for miR-122 can be easily silenced in hepatocytes because it has specificity for liver tissues (133). This strategy has been widely used to restrict transgene expression through a lentiviral vector in astroglial cells (134,135) (134,136).…”