New therapeutic target for pediatric anaplastic ependymoma control: study of anti-tumor activity by a Kunitz-type molecule, Amblyomin-X.

EPNs comprise a heterogeneous group of neuroepithelial tumors, accounting for about 10% of all intracranial tumors in children and up to 30% of brain tumors in those younger than 3 years. Actually, the pattern therapy for low-grade EPNs includes complete surgical resection followed by radiation therapy. Total surgical excision is often not possible due to tumor location. The aim of this study was to evaluate, for the first time, the anti-tumor activity of Amblyomin-X in 4 primary cultures derived from pediatric anaplastic posterior fossa EPN, Group A (anaplastic, WHO grade III) and one primary culture of a high grade neuroepithelial tumor with MN1 alteration, which was initially misdiagnosed as EPN: i) by in vitro assays: comparisons of temozolomide and cisplatin; ii) by intracranial xenograft model. Amblyomin-X was able to induce cell death in EPN cells in a more significant percentage compared to cisplatin. The cytotoxic effects of Amblyomin-X were not detected on hFSCs used as control, as opposed to cisplatin-treatment, which promoted a substantial effect in the hAFSCs viability. TEM analysis showed ultrastructural alterations related to the process of cell death: mitochondrial degeneration, autophagosomes and aggregate-like structures. MRI and histopathological analyzes demonstrated significant tumor mass regression. Our results suggest that Amblyomin-X has a selective effect on tumor cells by inducing apoptotic cell death and may be a therapeutic option for Group AEPNs.

Intravenous Grafts of Human Amniotic Fluid-Derived Stem Cells Reduce Behavioral Deficits in Experimental Ischemic Stroke.

Amniotic fluid has been investigated as new cell source for stem cells in the development of future cell-based transplantation. This study reports isolation of viable human amniotic fluid-derived stem cells, labeled with multimodal iron oxide nanoparticles, and its effect on focal cerebral ischemia-reperfusion injury in Wistar rats. Middle cerebral artery occlusion of 60 min followed by reperfusion for 1 h, 6 h, and 24 h was employed in the present study to produce ischemia and reperfusion-induced cerebral injury in rats. Tests were employed to assess the functional outcome of the sensorimotor center activity in the brain, through a set of modified neurological severity scores used to assess motor and exploratory capacity 24 h, 14, and 28 days after receiving cellular therapy via tail vein. In our animal model of stroke, transplanted cells migrated to the ischemic focus, infarct volume decreased, and motor deficits improved. Therefore, we concluded that these cells appear to have beneficial effects on the ischemic brain, possibly based on their ability to enhance endogenous repair mechanisms.

Tropism of mesenchymal stem cell toward CD133+ stem cell of glioblastoma in vitro and promote tumor proliferation in vivo.

BACKGROUND: Previous studies have demonstrated remarkable tropism of mesenchymal stem cells (MSCs) toward malignant gliomas, making these cells a potential vehicle for delivery of therapeutic agents to disseminated glioblastoma (GBM) cells. However, the potential contribution of MSCs to tumor progression is a matter of concern. It has been suggested that CD133+ GBM stem cells secrete a variety of chemokines, including monocytes chemoattractant protein-1 (MCP-1/CCL2) and stromal cell-derived factor-1(SDF-1/CXCL12), which could act in this tropism. However, the role in the modulation of this tropism of the subpopulation of CD133+ cells, which initiate GBM and the mechanisms underlying the tropism of MSCs to CD133+ GBM cells and their effects on tumor development, remains poorly defined. METHODS/RESULTS: We found that isolated and cultured MSCs (human umbilical cord blood MSCs) express CCR2 and CXCR4, the respective receptors for MCP-1/CCL2 and SDF-1/CXCL12, and demonstrated, in vitro, that MCP-1/CCL2 and SDF-1/CXC12, secreted by CD133+ GBM cells from primary cell cultures, induce the migration of MSCs. In addition, we confirmed that after in vivo GBM tumor establishment, by stereotaxic implantation of the CD133+ GBM cells labeled with Qdots (705 nm), MSCs labeled with multimodal iron oxide nanoparticles (MION) conjugated to rhodamine-B (Rh-B) (MION-Rh), infused by caudal vein, were able to cross the blood-brain barrier of the animal and migrate to the tumor region. Evaluation GBM tumors histology showed that groups that received MSC demonstrated tumor development, glial invasiveness, and detection of a high number of cycling cells. CONCLUSIONS: Therefore, in this study, we validated the chemotactic effect of MCP-1/CCL2 and SDF-1/CXCL12 in mediating the migration of MSCs toward CD133+ GBM cells. However, we observed that, after infiltrating the tumor, MSCs promote tumor growth in vivo probably by release of exosomes. Thus, the use of these cells as a therapeutic carrier strategy to target GBM cells must be approached with caution.