P11.12 Periostin is expressed by pericytes and is crucial for angiogenesis in glioma

BACKGROUND

The expression of the matricellular protein periostin has recently been associated with glioma progression and angiogenesis. The aim of the present study was to identify the cellular source of periostin expression in human gliomas and to study the role of periostin in an in vitro model for angiogenesis.

MATERIAL AND METHODS

The expression of periostin in various types and grades of brain tumors was investigated at the genetics level by RT-PCR and at the protein level by immunohistochemistry. In addition, the expression of periostin in glioma samples was studied by double labeling and in situ RNA techniques. Subsequently, by silencing periostin in a 3D in vitro angiogenesis model, its effects on angiogenesis were studied.

RESULTS

Periostin RNA and protein expression was found to be elevated in pilocytic astrocytoma and glioblastoma, but not in grade II/III astrocytomas. The expression of periostin co-localized with PDGFRβ + cells, but not with Olig2+ / Sox2+ glioma stem cells. Silencing of periostin in pericytes resulted in the attenuation of the number and the length of the vessels, and in decrease in the number of vessel junctions formed.

CONCLUSION

The results prove that pericytes are the main source of periostin in human gliomas. We demonstrate that periostin plays an essential role in the growth and branching of blood vessels. Therefore, periostin and / or its molecular interactions should be explored as a novel target for developing a new anti-angiogenic therapy for glioma.

P11.11 Circulating Pro-Angiogenic Cells and Proteins in Patients with Glioma and Acute Myocardial Infarction: Differences in Neovascularization between Neoplasia and Tissue Regeneration

BACKGROUND

Although extensive angiogenesis takes place in glial tumors, anti-angiogenic therapies have remained without the expected success. In the peripheral circulation of glioma patients increased numbers of endothelial precursor cells (EPCs) are present, potentially offering targets for anti-angiogenic therapy (Zheng et al., Ann Neurol, 2007). However, for an anti-angiogenic therapy to be successful, the therapy should specifically target glioma-related EPC subsets and secreted factors. Here we compared the EPC subsets and plasma factors in the peripheral circulation of patients with gliomas to acute myocardial infarctions (representing fysiologic regeneration).

MATERIAL AND METHODS

We investigated the five most important EPC subsets and 21 angiogenesis-related plasma factors in peripheral blood samples of 29 patients with glioma, 14 patients with myocardial infarction and 20 healthy people as controls, by an advanced FACS protocol (Huizer et al., PlosOne 2018) and Luminex assay.

RESULTS

In GBM patients all EPC subsets were elevated as compared to healthy subjects. In addition, HPC and KDR+ cell fractions were higher than in MI, while CD133+ and KDR+CD133+ cell fractions were lower. There were differences in relative EPC fractions between the groups: KDR+ cells were the largest fraction in GBM while CD133+ cells were the largest fraction in MI. An increase in glioma malignancy grade coincided with an increase in the KDR+ fraction while the CD133+ cell fraction decreased relatively. Most plasma angiogenic factors were higher in GBM than MI patients. In both MI and GBM, the ratio of CD133+ HPCs correlated significantly with elevated levels of MMP9. In the GBM patients MMP9 correlated strongly with levels of all HPCs.

CONCLUSION

In conclusion, the data demonstrate that EPC traffic in patients with glioma is different from that in normal tissue regeneration. Therefore, the effects of glioma extent beyond the brain, and future therapies aimed at lowering KDR+ cells and HPCs may add to effective treatment.

[Gene-expression profiling in schizophrenia: an overview]

BACKGROUND

In recent molecular-biological research it has become possible to study the activity of genes. Gene expression is characterized, among other things, by its variability and its dependence on the developmental phase of the organism, on the cell- and tissue-type, and on environmental factors. Now we have a technique by which the activity of the 30,000 or more genes that make up the human genome can be measured in one go. This technique is known as 'microarray screening', 'high-throughput-analysis, or gene-expression profiling'.

AIM

To describe some of the fundamentals of the gene-expression technique and to present an overview of the results of gene-expression studies of brain tissue taken from deceased patients.

METHOD

We searched PubMed for relevant articles using the search terms 'schizophrenia', 'micro-array' and 'gene expression'. We located 10 articles/studies.

RESULTS AND CONCLUSION

We conclude that gene-expression profiling has produced some evidence that several functional groups of genes are involved in schizophrenia (e.g. gene groups relating to synapses, metabolism, myelination and oligodendrocytes). Several of these genes are located on known chromosomal risk loci for schizophrenia. Together these findings support the theories that postulate that schizophrenia is caused by disturbances in synaptic stability and plasticity. There is some evidence that disturbances in myelination and fatty-acid metabolism may also play a role.