Predictive immunotherapy models

While activated human and mouse T cells are easily transduced with lentiviral vectors, transduction of naive and regulatory T cells is a technical challenge since these target cells are poorly permissive to transfection or viral transduction.

Overcoming the challenge of T cells gene transfer with lentiviral vectors

Vectalys extensive in vitro transduction data show that the use of highly concentrated (1E9 TU/mL) and pure (1E8 TU/mg of proteins) lentiviral vectors increases significantly the transduction level of naive and regulatory CD4+ T cells.

Naive and activated human total T lymphocytes

Lentiviral vectors human naïve T cells

Naive and activated murine CD4+ T lymphocytes

Lentiviral vectors murine naïve T cells

T cells keep their phenotype and specific markers expression

Furthermore, transduced T cells exhibit their original cell phenotype without any changes of T cells specific markers expression (CD44, CD69, CD25, Ly-6C) attesting that the composition of this pure batch of lentiviral vectors does not have any impact on T cells phenotype.

Naive phenotype of murine CD4+ T lymphocytes is maintained

Human T cells keep original phenotype

Naive CD4+ T lymphocyte are transduced by a ZsGreen-expressing lentiviral vector at MOI 10 in presence of polybrene 4µu/mL for 5h at 37°C, 5% CO2.

Four days later, the expression pattern of naive markers (CD44, CD25, CD69 and Ly-6C) and fluorescence intensity are analyzed by flow cytometry. Cell activation (anti-CD3/CD28 coupled beads) is performed on one sample 16h after transduction as a control. The naive phenotype of T cells is characterized by a low expression of CD44, which is an indicative marker for effector-memory T-cells, no expression of CD25 which is expressed specifically on stimulated T cells, nor CD69 which is an early marker of activation. Ly6 is down regulated on activated cells and it is thus found expressed on these naive T cells.

Regulatory murine CD4+ T lymphocytes

Murine T cells keep original phenotype

GFP-expressing CD4+ regulatory T lymphocyte (Tregs) are obtained from FoxP3-GFP mice. Tregs are FACS-sorted as GFP positive cells, then transduced by a tdTomato-expressing lentiviral vector at MOI 10 in presence of ploybrene 4µg/mL for 5h at 37°C, 5% CO2. Five days post-transduction, the % of tdTomato positive cells and Fluorescence Intensity are analyzed by cytometry.

Lentiviral vectors: a major technological leap

Our data bring out that the composition of lentiviral vectors in terms of titer, specific activities and purity are the success keys to ensure transduction of immune cells. This major technological leap will allow to tightly control expression of various modifiers of these cells and thus paves the way to design original tools and to develop cell-based cancer models.

Gene transfer using concentrated and highly purified lentiviral vectors is the best way to obtain a stable expression of the sequence of interest (cDNA, shRNA, miRNA, CRISPR/Cas9). Compared to transfection or standard lentiviral vectors, they allow time, money, and energy saving, providing a single tool from in vitro to in vivo applications.

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