Delivery Platforms for CRISPR/Cas9 Genome Editing of Glial Cells in the Central Nervous System.

Vasco Meneghini,Angela Gritti,Marco Peviani,Marco Luciani,Giada Zambonini

doi:10.3389/fgeed.2021.644319

Abstract

Glial cells (astrocytes, oligodendrocytes, and microglia) are emerging as key players in several physiological and pathological processes of the central nervous system (CNS). Astrocytes and oligodendrocytes are not only supportive cells that release trophic factors or regulate energy metabolism, but they also actively modulate critical neuronal processes and functions in the tripartite synapse. Microglia are defined as CNS-resident cells that provide immune surveillance; however, they also actively contribute to shaping the neuronal microenvironment by scavenging cell debris or regulating synaptogenesis and pruning. Given the many interconnected processes coordinated by glial cells, it is not surprising that both acute and chronic CNS insults not only cause neuronal damage but also trigger complex multifaceted responses, including neuroinflammation, which can critically contribute to the disease progression and worsening of symptoms in several neurodegenerative diseases. Overall, this makes glial cells excellent candidates for targeted therapies to treat CNS disorders. In recent years, the application of gene editing technologies has redefined therapeutic strategies to treat genetic and age-related neurological diseases. In this review, we discuss the advantages and limitations of clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9-based gene editing in the treatment of neurodegenerative disorders, focusing on the development of viral- and nanoparticle-based delivery methods for in vivo glial cell targeting.

Highlights

In the past, there was a “neuron-centric” point of view of neuroscience in which glial cells were mainly relegated to a structural/metabolic supportive role and rarely they were described as key players in the onset of neurodegenerative disorders
clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 Editing in Glia Cells (Kuhn et al, 2019), and metabolically support neurons and regulate the action potential firing by secreting ions (e.g., Ca2+ and K+) (Battefeld et al, 2016), catabolites, neurotrophic factors [e.g., glial cell-derived neurotrophic factor (GDNF), brain-derived neurotrophic factor (BDNF), and insulin-like growth factor 1 (IGF-1)] (Takasaki et al, 2010) and anti-apoptotic agents (Taniike et al, 2002)
While associated virus (AAV) biodistribution was limited in animals injected beyond neonatal day P1, administration in the later periods of post-natal development resulted in an increased non-neuronal transduction with an enhanced rate of astrocyte infection in mice injected at P2 and P3 post-natal days (Chakrabarty et al, 2013)

Summary

Introduction

There was a “neuron-centric” point of view of neuroscience in which glial cells were mainly relegated to a structural/metabolic supportive role and rarely they were described as key players in the onset of neurodegenerative disorders. In the table are reported the more relevant in vitro and in vivo studies evaluating the editing efficiency upon delivery of Cas9 nucleases (NHEJ, HDR, and HMEJ pathways), base editors (CBEs and ABEs) and epigenome editors in neurons and/or glia cells (Astro, astrocytes; OLs, oligodendrocytes; Müller, müller glia cells; Microglia).

Results

Conclusion