Kinin and Purine Signaling Contributes to Neuroblastoma Metastasis.

Bone marrow metastasis occurs in approximately 350,000 patients that annually die in the U.S. alone. In view of the importance of tumor cell migration into the bone marrow, we have here investigated effects of various concentrations of stromal cell-derived factor-1 (SDF-1), bradykinin- and ATP on bone marrow metastasis. We show for first time that bradykinin augmented chemotactic responsiveness of neuroblastoma cells to SDF-1 and ATP concentrations, encountered under physiological conditions. Bradykinin upregulated VEGF expression, increased metalloproteinase activity and induced adhesion of neuroblastoma cells. Bradykinin augmented SDF-1-induced intracellular Ca2+ mobilization as well as resensitization and expression of ATP-sensing P2X7 receptors. Bradykinin treatment resulted in higher gene expression levels of the truncated P2X7B receptor compared to those of the P2X7A full-length isoform. Bradykinin as pro-metastatic factor induced tumor proliferation that was significantly decreased by P2X7 receptor antagonists; however, the peptide did not enhance cell death nor P2X7A receptor-related pore activity, promoting neuroblastoma growth. Furthermore, immunodeficient nude/nude mice transplanted with bradykinin-pretreated neuroblastoma cells revealed significantly higher metastasis rates compared to animals injected with untreated cells. In contrast, animals receiving Brilliant Blue G, a P2X7 receptor antagonist, did not show any specific dissemination of neuroblastoma cells to the bone marrow and liver, and metastasis rates were drastically reduced. Our data suggests correlated actions of kinins and purines in neuroblastoma dissemination, providing novel avenues for clinic research in preventing metastasis.

Modification of the natural progression of epileptogenesis by means of biperiden in the pilocarpine model of epilepsy.

Brain injuries are often associated with the later development of epilepsy. Evidence suggests that morphological and functional changes occur in the remaining neural tissue during a silent (or latent) period in which no seizures are expressed. It is believed that this silent (reorganization) period may provide a therapeutic window for modifying the natural history of disease progression. Here we provide evidence that biperiden, a muscarinic anticholinergic agent, is able to alter disease progression in an animal model of epilepsy. We observed that biperiden was capable of slowing the manifestation of the first spontaneous epileptic seizure and effectively reduced the severity and number of recurrent, spontaneous epileptic seizures during the animals' lifespan. Biomolecular (microdialysis) and electrophysiological (extracellular field recordings) studies determined that biperiden was capable of elevating the threshold of hippocampal excitability, thereby making the hippocampal glutamatergic pathways less responsive to stimuli when high concentrations of potassium were used in vivo or in vitro. Notably, there was no hindrance of long-term memory or learning (a potential problem given the amnestic nature of biperiden). We conclude that biperiden has antiepileptogenic potential and may represent an opportunity for the prevention of post-traumatic epilepsy.

Brilliant Blue G, But Not Fenofibrate, Treatment Reverts Hemiparkinsonian Behavior and Restores Dopamine Levels in an Animal Model of Parkinson's Disease.

Parkinson's disease (PD) is a neurodegenerative disorder, characterized by the loss of dopaminergic neurons in the substantia nigra and their projections to the striatum. Several processes have been described as potential inducers of the dopaminergic neuron death, such as inflammation, oxidative stress, and mitochondrial dysfunction. However, the death of dopaminergic neurons seems to be multifactorial, and its cause remains unclear. ATP-activating purinergic receptors influence various physiological functions in the CNS, including neurotransmission. Purinergic signaling is also involved in pathological scenarios, where ATP is extensively released and promotes sustained purinergic P2X7 receptor (P2X7R) activation and consequent induction of cell death. This effect occurs, among other factors, by oxidative stress and during the inflammatory response. On the other hand, peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) is involved in energy metabolism and mitochondrial biogenesis. Expression and activity upregulation of this protein has been related with reduction of oxidative stress and neuroprotection. Therefore, P2X7R and PGC-1α are potential targets in the treatment of PD. Here hemiparkinsonism was induced by unilateral stereotactic injection of 6-OHDA in a rat model. After 7 days, the establishment of PD was confirmed and followed by treatment with the P2X7R antagonist Brilliant Blue G (BBG) or PGC-1α agonist fenofibrate. BBG, but not fenofibrate, reverted hemiparkinsonian behavior accompanied by an increase in tyrosine hydroxylase immunoreactivity in the substantia nigra. Our results suggest that the P2X7R may be a therapeutic target in Parkinson's disease.

The Anti-Tumor Effects of Adipose Tissue Mesenchymal Stem Cell Transduced with HSV-Tk Gene on U-87-Driven Brain Tumor.

Glioblastoma (GBM) is an infiltrative tumor that is difficult to eradicate. Treating GBM with mesenchymal stem cells (MSCs) that have been modified with the HSV-Tk suicide gene has brought significant advances mainly because MSCs are chemoattracted to GBM and kill tumor cells via a bystander effect. To use this strategy, abundantly present adipose-tissue-derived mesenchymal stem cells (AT-MSCs) were evaluated for the treatment of GBM in mice. AT-MSCs were prepared using a mechanical protocol to avoid contamination with animal protein and transduced with HSV-Tk via a lentiviral vector. The U-87 glioblastoma cells cultured with AT-MSC-HSV-Tk died in the presence of 25 or 50 µM ganciclovir (GCV). U-87 glioblastoma cells injected into the brains of nude mice generated tumors larger than 3.5 mm2 after 4 weeks, but the injection of AT-MSC-HSV-Tk cells one week after the U-87 injection, combined with GCV treatment, drastically reduced tumors to smaller than 0.5 mm2. Immunohistochemical analysis of the tumors showed the presence of AT-MSC-HSV-Tk cells only within the tumor and its vicinity, but not in other areas of the brain, showing chemoattraction between them. The abundance of AT-MSCs and the easier to obtain them mechanically are strong advantages when compared to using MSCs from other tissues.

Anticonvulsant activity of bone marrow cells in electroconvulsive seizures in mice.

BACKGROUND: Bone marrow is an accessible source of progenitor cells, which have been investigated as treatment for neurological diseases in a number of clinical trials. Here we evaluated the potential benefit of bone marrow cells in protecting against convulsive seizures induced by maximum electroconvulsive shock (MES), a widely used model for screening of anti-epileptic drugs. Behavioral and inflammatory responses were measured after MES induction in order to verify the effects promoted by transplantation of bone marrow cells. To assess the anticonvulsant effects of bone marrow cell transplantation, we measured the frequency and duration of tonic seizure, the mortality rate, the microglial expression and the blood levels of cytokine IL-1, IL-6, IL-10 and TNF-α after MES induction. We hypothesized that these behavioral and inflammatory responses to a strong stimulus such as a convulsive seizure could be modified by the transplantation of bone marrow cells. RESULTS: Bone marrow transplanted cells altered the convulsive threshold and showed anticonvulsant effect by protecting from tonic seizures. Bone marrow cells modified the microglial expression in the analyzed brain areas, increased the IL-10 and attenuate IL-6 levels. CONCLUSIONS: Bone marrow cells exert protective effects by blocking the course of electroconvulsive seizures. Additionally, electroconvulsive seizures induced acute inflammatory responses by altering the pattern of microglia expression, as well as in IL-6 and IL-10 levels. Our findings also indicated that the anticonvulsant effects of these cells can be tested with the MES model following the same paradigm used for drug testing in pharmacological screening. Studies on the inflammatory reaction in response to acute seizures in the presence of transplanted bone marrow cells might open a wide range of discussions on the mechanisms relevant to the pathophysiology of epilepsies.

Effect of the bone marrow cell transplantation on elevated plus-maze performance in hippocampal-injured mice.

Several reports have shown that the hippocampus plays an important role in different aspects of the emotional control. There is evidence that lesions in this structure cause behavioral disinhibition, with reduction of reactions expressing fear and anxiety. Thus, to portray the aptitude of cell therapy to abrogate injuries of hippocampal tissue, we examined the behavioral effects of bone marrow mononuclear cells (BMMCs) transplantation on C57BL/6 mice that had the hippocampus damaged by electrolytic lesion. For this purpose, mice received, seven days after bilateral electrolytic lesion in the dorsal hippocampus, culture medium or BMMCs expressing the enhanced green fluorescent protein (EGFP) transgene. One week after transplantation, animals were tested in the elevated plus-maze (EPM). On the whole, three assessment sessions in the EPM were carried out, with seven days separating each trial. Thirty-five days after the induction of injury, mice were sacrificed and their brains removed for immunohistochemistry. The behavioral evaluation showed that the hippocampal lesion caused disinhibition, an effect which was slightly lessened, from the second EPM test, in transplanted subjects. On the other hand, immunohistochemical data revealed an insignificant presence of EGFP(+) cells inside the brains of injured mice. In view of such scenario, we hypothesized that the subtle rehabilitation of the altered behavior might be a result from a paracrine effect from the transplanted cells. This might have been caused by the release of bioactive factors capable of boosting endogenous recuperative mechanisms for a partial regaining of the hippocampal functions.