Development of anti-GD2 Antibody-producing Mesenchymal Stem Cells as Cellular Immunotherapy.

BACKGROUND/AIM: Using the tyrosine hydroxylase (TH)-MYCN mouse neuroblastoma (NB) model, we have previously reported the accumulation of mouse mesenchymal stem cells (mMSCs) on tumors in vivo and the antitumor effect of mMSCs transfected with a small molecule (IFN-β) expression gene. In this study, we have developed novel MSCs secreting anti-disialoganglioside GD2 antibody (anti-GD2-MSCs) and evaluated their antitumor effects in vitro.

MATERIALS AND METHODS: We generated an anti-GD2 antibody construct (14.G2a-Fcx2-GFP) incorporating FLAG-tagged single-chain fragment variable against GD2 fused to a linker sequence, a fragment of the constant portion of human IgG1, and GFP protein. The construct was lentivirally transduced into mMSCs and the transduction efficiency was assessed by GFP expression. The secretion of FLAG-tagged anti-GD2 antibody was detected by Western blotting using anti-FLAG antibody. Antibody binding capacity was confirmed by flow cytometry. Antibody-dependent cellular cytotoxicity (ADCC) was evaluated using human NB cells and human natural killer (NK) cells to assess whether the antitumor activity was enhanced in the presence of the produced antibodies.

RESULTS: The transduction efficiency of anti-GD2-MSCs was more than 90%. anti-GD2-MSCs secreted antibodies extracellularly and these antibodies had high affinity to GD2-expressing human NB cells. ADCC assays showed that the addition of antibodies secreted from anti-GD2-MSCs significantly increased the cytotoxic activity of NK cells against NB cells.

CONCLUSION: Newly developed anti-GD2-MSCs produced functional antibodies that have affinity to the GD2 antigen on NB cells and can induce ADCC-mediated cytotoxicity. Anti-GD2-MSCs based cellular immunotherapy has the potential to be a novel therapeutic option for intractable NB.