Lentivirus- or AAV-mediated gene therapy interventions in ischemic stroke: A systematic review of preclinical in vivo studies

Abstract

Due to the limited therapeutic options after ischemic stroke, gene therapy has emerged as a promising choice, especially with recent advances in viral vector delivery systems. Therefore, we aimed to provide the current state of the art of lentivirus (LV) and adeno-associated virus (AAV) mediated gene interventions in preclinical ischemic stroke models. A systematic analysis including qualitative and quantitative syntheses of studies published until December 2020 was performed. Most of the 87 selected publications used adult male rodents and the preferred stroke model was transient middle cerebral artery occlusion. LV and AAV vectors were equally used for transgene delivery, however loads of AAVs were higher than LVs. Serotypes having broad cell tropism, the use of constitutive promoters, and virus delivery before the stroke induction via stereotaxic injection in the cortex and striatum were preferred in the analyzed studies. The meta-analysis based on infarct volume as the primary outcome confirmed the efficacy of the preclinical interventions. The quality assessment exposed publication bias and setbacks in regard to risks of bias and study relevance. The translational potential could increase by using specific cell targeting, post-stroke interventions, non-invasive systematic delivery, and use of large animals.

Keywords: Adeno-associated virus; gene therapy; infarct; ischemic stroke; lentivirus.

Figure 1.

Flow chart of selection process of the analyzed articles. A systematic search in online databases yielded 440 publications. After duplicates removal and application of inclusion criteria total of 87 publication was used for qualitative and 55 for quantitative synthesis.

Figure 2.

Data related to the viral vector construction and administration. (a) Virus type used in selected studies; total number was 89 as some studies used more than one virus type, (b) virus delivery route; total number was 94 as some studies used several routes of administration, (c) timepoint of virus administration, (d) brain location to which virus was stereotaxically injected. LV: lentivirus; AAV: adeno-associated virus.

Figure 3.

Data related to the viral vector construction and administration. (a) Total amount of viral vector injected per animal, (b) total volume of viral vector injected in brain parenchymal tissue or ventricular system, (c) volume of AAV or LV injected per animal, (d) timepoint and methods used for evaluation of virus transduction efficacy. LV: Lentivirus; AAV: Adeno-associated virus; Luciferase AA: luciferase activity assay; IHC: Immunohistochemical staining; WB: Western blot; qPCR: Quantitative polymerase chain reaction; ELISA: The enzyme-linked immunosorbent assay; RNAseq: RNA sequencing; T7: T7E1 mutation detection assay.

Figure 4.

Overall effect of viral vector mediated gene therapy on infarct volume. Forest plot of standardized mean differences (SMD) with 95% confidence intervals (CI).

Figure 5.

Risk of bias assessed by modified SYRCLE criteria. The category “Other sources of bias” includes conflict of interest, funding sources and compliance to animal welfare regulations.

Figure 6.

Study relevance assessment.

Figure 7.

Subgroup comparisons on the effect of the viral vector mediated gene therapy on infarct volume. Forest plot of standardized mean differences (SMD) with 95% confidence intervals (CI) for virus types, timepoints of virus administration, animal species use and relative vs. absolute measures of the infarct volumes. Dashed line represents overall effect size (-1.82) of all studies included in meta-analysis.

Figure 8.

Funnel plot of the infarct volumes. The blue shaded area represents 95% confidence interval.