Adeno-associated viral vector-mediated gene transduction in mesencephalic slice culture

New uses for an old technique: live imaging on the slice organ culture to study reproductive processes†

Reproductive processes are dynamic and involve extensive morphological remodeling and cell-cell interactions. Live imaging of organs enhances our understanding of how biological processes occur in real time. Slice culture is a type of organ culture where thick slices are collected from an organ and cultured for several days. Slice culture is a useful and easy-to-implement technique for live imaging of reproductive events at cellular resolution. Here we describe a pipeline of live imaging on slice culture to visualize the process of urethra closure in mouse embryonic penis as a proof of principle. In combination with genetic reporter mice, nuclear stains, and exposure experiments, we demonstrate the feasibility of slice culture on a reproductive organ. We also provide a step-by-step protocol and troubleshooting guide to facilitate the adoption of slice culture with live imaging in other reproductive organs. Lastly, we discuss potential utilities and experiments that could be implemented with slice culture in reproductive sciences.

Synthetic Monopartite Peptide That Enables the Nuclear Import of Genes Delivered by the Neurotensin-Polyplex Vector

Neurotensin (NTS)-polyplex is a multicomponent nonviral vector that enables gene delivery via internalization of the neurotensin type 1 receptor (NTSR1) to dopaminergic neurons and cancer cells. An approach to improving its therapeutic safety is replacing the viral karyophilic component (peptide KPSV40; MAPTKRKGSCPGAAPNKPK), which performs the nuclear import activity, by a shorter synthetic peptide (KPRa; KMAPKKRK). We explored this issue and the mechanism of plasmid DNA translocation through the expression of the green fluorescent protein or red fluorescent protein fused with KPRa and internalization assays and whole-cell patch-clamp configuration experiments in a single cell together with importin α/β pathway blockers. We showed that KPRa electrostatically bound to plasmid DNA increased the transgene expression compared with KPSV40 and enabled nuclear translocation of KPRa-fused red fluorescent proteins and plasmid DNA. Such translocation was blocked with ivermectin or mifepristone, suggesting importin α/β pathway mediation. KPRa also enabled NTS-polyplex-mediated expression of reporter or physiological genes such as human mesencephalic-derived neurotrophic factor (hMANF) in dopaminergic neurons in vivo. KPRa is a synthetic monopartite peptide that showed nuclear import activity in NTS-polyplex vector-mediated gene delivery. KPRa could also improve the transfection of other nonviral vectors used in gene therapy.

Construction of AAV-rat-IL4 and Evaluation of its Modulating Effect on Aβ (1-42)-Induced Proinflammatory Cytokines in Primary Microglia and the B92 Cell Line by Quantitative PCR Assay

BACKGROUND

Interleukin-4 (IL-4), as the most prominent anti-inflammatory cytokine, plays an important role in modulating microglial activation and inflammatory responses in Alzheimer's disease (AD), a chronic inflammatory disorder.

OBJECTIVES

The current study aimed to develop a new recombinant Adeno-associated viral (rAAV) vector that delivers IL-4 and then assess the counterbalancing effect of the new construct along with recombinant IL-4 (rIL-4) protein in in-vitro models of AD.

MATERIALS AND METHODS

The rAAV-IL4 was originally prepared and then employed along with rIL-4 protein to counter Amyloid β (1-42)-induced proinflammatory cytokines in a primary microglia cell culture and the B92 rat microglia continuous cell line, using relative Real-Time PCR assay.

RESULTS

Aβ (1-42) stimulated the production of the proinflammatory cytokines IL6, IL1β, TNFα, and IL18 in both the primary microglia cell culture and the B92 cell line. Both the rAAV-IL4 construct and the rIL-4 protein were found to inhibit production of the most important Aβ (1-42)-induced proinflammatory cytokine mRNAs in the two types of cells with different patterns.

CONCLUSIONS

It seems that the new construct can serve as an appropriate option in the modulation of Aβ-induced proinflammatory cytokine gene expression and microglia activation in patients affected by AD.

An ex-vivo multiple sclerosis model of inflammatory demyelination using hyperbranched polymer

Multiple sclerosis (MS) is characterized by the presence of inflammatory demyelinating foci throughout the brain and spinal cord, accompanied by axonal and neuronal damage. Although inflammatory processes are thought to underlie the pathological changes, the individual mediators of this damage are unclear. In order to study the role of pro-inflammatory cytokines in demyelination in the central nervous system, we have utilized a hyperbranched poly(2-dimethyl-aminoethylmethacrylate) based non-viral gene transfection system to establish an inflammatory demyelinating model of MS in an ex-vivo environment. The synthesized non-viral gene transfection system was optimized for efficient transfection with minimal cytotoxicity. Organotypic brain slices were then successfully transfected with the TNF or IFNγ genes. TNF and IFNγ expression and release in cerebellar slices via non-viral gene delivery approach resulted in inflammation mediated myelin loss, thus making it a promising ex-vivo approach for studying the underlying mechanisms of demyelination in myelin-related diseases such as MS.

Optimizing NTS-polyplex as a tool for gene transfer to cultured dopamine neurons

The study of signal transduction in dopamine (DA)-containing neurons as well as the development of new therapeutic approaches for Parkinson's disease requires the selective expression of transgenes in such neurons. Here we describe optimization of the use of the NTS-polyplex, a gene carrier system taking advantage of neurotensin receptor internalization, to transfect mouse DA neurons in primary culture. The plasmids DsRed2 (4.7 kbp) and VGLUT2-Venus (11 kbp) were used to compare the ability of this carrier system to transfect plasmids of different sizes. We examined the impact of age of the neurons (1, 3, 5 and 8 days after seeding), of culture media used during the transfection (Neurobasal with B27 vs. conditioned medium) and of three molar ratios of plasmid DNA to carrier. While the NTS-polyplex successfully transfected both plasmids in a control N1E-115 cell line, only the pDsRed2 plasmid could be transfected in primary cultured DA neurons. We achieved 20% transfection efficiency of pDsRed2 in DA neurons, with 80% cell viability. The transfection was demonstrated pharmacologically to be dependent on activation of neurotensin receptors and to be selective for DA neurons. The presence of conditioned medium for transfection was found to be required to insure cell viability. Highest transfection efficiency was achieved in the most mature neurons. In contrast, transfection with the VGLUT2-Venus plasmid produced cell damage, most likely due to the high molar ratios required, as evidenced by a 15% cell viability of DA neurons at the three molar ratios tested (1:36, 1:39 and 1:42). We conclude that, when used at molar ratios lower than 1:33, the NTS-polyplex can selectively transfect mature cultured DA neurons with only low levels of toxicity. Our results provide evidence that the NTS-polyplex has good potential for targeted gene delivery in cultured DA neurons, an in vitro system of great use for the screening of new therapeutic approaches for Parkinson's disease.