Enhancing Immunogenicity of Embryonic Stem Cells by Expression of Granulocyte Macrophage-Colony Stimulating Factor

Overview

Antigenic similarity between tumor cells and embryonic stem cells has been recognized for many years. However, treatments harnessing this similarity have achieved little success, largely due to the development of tumor-induced immune tolerance. An alternative to this strategy is prophylactic vaccination against shared antigens, inducing immunity before cancer begins to develop. Prior research has shown that a two-part vaccine consisting of allogeneic murine embryonic stem cells (ES-D3) and STO fibroblasts expressing the adjuvant granulocyte macrophage-colony stimulating factor (GM-CSF) significantly reduces outgrowth of implanted and induced lung carcinomas in mice. However, because this vaccine contained whole cells, it could not be tested in humans due to the risk of teratoma development. The objective of this research was to eliminate these whole cells to work towards a final version of the vaccine. To this purpose, GM-CSF was expressed in ES-D3 cells by two different approaches, transfection (selected by GFP) and lentiviral infection (selected by puromycin), eliminating the need for GM-CSF-expressing STO fibroblasts. After expression, GM-CSF concentrations were evaluated by ELISA—STO fibroblasts, GFP GM-CSF, and Puro GM-CSF cells displayed concentrations of 50.304 ng/mL, 48.870 mg/mL, and 57.043 ng/mL, respectively. Then, it was verified that these cells maintained their pluripotency—and therefore their shared tumor antigens—through immunofluorescence and flow cytometry. GM-­CSF expression did not modulate pluripotency of ES­-D3 cells; both lines of GM-­CSF-­expressing ES­-D3 cells showed high-level expression of SSEA­1, a marker for pluripotency, and Oct­-3/4, a transcription factor, as well as low-level expression of SSEA­4, a marker for differentiation. This research represents a significant step forward in the development of a new generation of safe and effective vaccines for prophylactic cancer prevention.

Competition history

• AJAS 2018 Category not listed

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