The In Vitro Tumor Tropism Of IL-24Gene-modified Mesenchymal Stem Cells For Lung Cancer

Background and ObjectiveMesenchymal stem cells (MSCs) are a group of stem cells in post-natal tissues, and it has been assumed that MSCs resided in all organs with connective tissue. Owing to their easy access from various tissue sources (such as bone marrow, adipose tissue, umbilical cord), immune-privileged nature, robust ex vivo manipulation with minimal loss of stem cell characteristics, MSCs are recognized as the most attractive candidates for stem cell based therapies. Interleukin-24, also designated as melanoma differentiation associated gene-7(MDA-7), has been recognized as a novel tumor suppressor gene that selectively inhibits tumor growth by inducing apoptosis, anti-neoangiogenesis and stimulating immunological tumor eradication while avoiding injuring healthy tissues. Using lentivirus transductions, we confirmed the tumor tropisms of IL-24expressing MSCs towards lung cancer A549and H2228, and set foundations for future researches on the antitumor mechanisms in vitro and in vivo.Materials and Methods1. Umbilical cord mesenchymal stem cells(UCMSCs) were isolated from minced umbilical cord tissues; cell phenotype of CD105,CD73,CD44,CD29,CD34and CD45in passage4were identified by flow cytometry; multi-potentials of these cells were tested by osteogenic differentiation and adipogenic differentiation in vitro; 2. MSCs were transfected with enhanced green fluorescent protein(EGFP) gene labeled IL-24or control lentivirus vector in the construction of IL-24expressing MSCs(MSCs-IL-24)or control MSCs(MSCs-EGFP);tumor tropisms of MSCs-IL-24, MSCs-EGFP and MSCs towards A549or H2228were determined by Matrigel coated Transwell with8micron pores on bottom membranes;3. rIL-24levels in conditioned medium supernatants from three groups of MSCs were tested by ELISA kits and Western Blot. All data were analyzed at significance level of0.05by SPSS version16.Results1. Ten to14days post primary cultures, cells of spindle shape swam off the edge of tissue pieces; flow cytometry confirmed these cells a phenotype of CD105(96.76%), CD73(97.64%), CD44(96.07%), CD29(97.5%), CD34(0.77%) and CD45(0.82%); Osteogenic differentiations and adipogenic differentiations were observed;2. Green fluorescence were observed in MSCs(about55-60%)96h after initial transductions; ELISA noted37.07±2.66ng/mL of rIL-24in conditioned medium supernatants derived from MSCs-IL-24; Western blotting revealed rIL-24expression in MSCs-IL-24;3. In vitro tumor oriented migration towards A549or H2228revealed no difference (P>0.05) among MSCs-IL-24, MSCs-EGFP and MSCs.Conclusions1) MSCs could be isolated from minced human umbilical cord tissue;2) rIL-24expressing MSCs could be constructed by lentivirus transfections;3) Tumor tropisms of MSCs would not be affected after lentivirus transfections, providing tools for in vivo studies.