Evaluation Of The Effect Of Mesenchymal Stem Cells On Chemotherapy Response For Neuroblastoma Treatment In An Experimental Animal Model

High-dose cisplatin (CDDP) causes dose-limiting side effects in neuroblastoma (NB) treatment. Mesenchymal stem cells (MSC) are a current research area in cellular treatments due to multipotential characteristics. The aim of this study is to assess the interaction of MSC with CDDP in an athymic nude mouse NB model. Athymic male nude mice (n=28) were injected subcutaneously with C1300 NB cell line. After tumor growth to 1 cm diameter in 7-10 days, mice were randomly assigned to one of 4 experimental groups of control, CDDP treatment, MSC treatment and CDDP+MSC treatment with 7 mice in each group. Animals had basal auditory tests performed and had physiological serum or CDDP (20 mg/kg) injected into the peritoneum and were intravenously injected with 1x105 MSC once. Seven days later, hearing tests were performed again and the animals were sacrificed. Tumor tissue was assessed in terms of necrosis, apoptosis and viability. Apoptosis was evaluated with annexin V+PI flow cytometry analysis and TUNEL. Additionally, the MSC rate within the tumor was assessed with flow cytometry for triple CD34+ CD44+ and CD117-expression. Additionally, liver, kidney, brain and cochlear tissue were analyzed with light microscopy in terms of systemic side effect profile. Expression of the cochlear cell proteins of calretinin, math-1 and myosin2A were immunohistochemically assessed in ear sections. Statistical analysis used the nonparametric Kruskal Wallis and Mann Whitney U tests with p<0.05 significance. Tumor tissues were found to have statistically significantly higher levels of necrosis in the CDDP group and CDDP+MSC group compared to the control and MSC groups (p=0.001, p=0.006). The CDDP+MSC group had lower tumor necrosis rates than the CDDP group but this was not observed to have statistical significance (p=0.05). MSC did not change the tumor dimensions in the CDDP group (p=0.557). The groups administered MSC had higher triple CD34+ CD44+ and CD117- expression within tumor tissue compared to the control and CDDP groups. In the inner ear, the expression of cochlear cell proteins calretinin, math-1 and myosin2A were identified to be highest in the groups administered MSC. Auditory tests observed that the 15-decibel loss at 12, 16, 20 and 32 kHz frequencies in both ears with CDDP was resolved with MSC administration. With this study, IV administration of MSC treatment was observed to prevent the hearing loss caused by CDDP without disrupting the antitumor effect of CDDP. Systemic MSC may be assessed for clinical use to reduce the side effects of CDDP.