Impact of mesenchymal stem cells and tumor infiltrating lymphocytes to cancer stem cells in neuroblastoma

Neuroblastoma (NB) is the most common extra-cranial solid tumor in childhood. Cancer stem cells(CSCs) are thought to play a central role in tumor initiation, progression and recurrence. Increased levels of CSCs are associated with poor prognosis. The aim of this study is to investigate the interaction between neuroblastoma cells, CSCs and the elements of tumor microenvironment which is tumor infiltrating lymphocytes(TILs) and mesenchymal stem cells(MSC) ex vivo for the first time. Isolated fresh tissues of neuroblastoma surgical material were perfomed single-cell suspension and cultured. CD133+ stem cells were isolated using magnetic isolation from cultured neuroblastoma cancer cells. TILs were isolated by AIMV medium migration method MSC were isolated with CD54+, CD90+ magnetic isolation. The isolated cells, tumor infiltrating lymphocytes and cisplatin were seeded in multi-well Plates Then the viability of cells measured at 24 and 48 hours. Also phenotype of TILs were identified by flow cytometry and immunohistochemistry. Result were analysed by nonparametric tests at p<0.05 level. A total of 20 neuroblastoma samples from patients who are 2 to 168 (mean 39) months old, were evaluated with cell culture 8 of them were at low risk group and 12 were at high-risk group. Ten females and ten males were included in the study. We found that MSCs reduce the killing effect of CDDP on CSC reducing apoptotic effect. We have also found that TILs increase the killing effect of CDDP on NB and CSC. Proving this interaction offers useful information to consider microenvironment in planning neuroblastoma and CSC-targeted therapies. Keywords: Neuroblastoma Cancer Stem Cell, Mesenchymal Stem Cells, Microenvironment, Tumor Infiltrating Lymphocytes