Spermatogonial kinetics in humans.

The human spermatogonial compartment is essential for daily production of millions of sperm. Despite this crucial role, the molecular signature, kinetic behavior and regulation of human spermatogonia are poorly understood. Using human testis biopsies with normal spermatogenesis and by studying marker protein expression, we have identified for the first time different subpopulations of spermatogonia. MAGE-A4 marks all spermatogonia, KIT marks all B spermatogonia and UCLH1 all Apale-dark (Ap-d) spermatogonia. We suggest that at the start of the spermatogenic lineage there are Ap-d spermatogonia that are GFRA1High, likely including the spermatogonial stem cells. Next, UTF1 becomes expressed, cells become quiescent and GFRA1 expression decreases. Finally, GFRA1 expression is lost and subsequently cells differentiate into B spermatogonia, losing UTF1 and acquiring KIT expression. Strikingly, most human Ap-d spermatogonia are out of the cell cycle and even differentiating type B spermatogonial proliferation is restricted. A novel scheme for human spermatogonial development is proposed that will facilitate further research in this field, the understanding of cases of infertility and the development of methods to increase sperm output.

Regulation of Gdnf expression by retinoic acid in Sertoli cells.

Glial cell line-derived neurotrophic factor (GDNF) and retinoic acid (RA) are two molecules crucial for the regulation of the spermatogonial compartment of the testis. During the cycle of the seminiferous epithelium, their relative concentration oscillates with lower GDNF levels in stages where RA levels are high. It has been recently shown that RA negatively regulates Gdnf expression but the mechanisms behind are so far unknown. Here, we show that RA directly downregulates Gdnf mRNA levels in primary murine Sertoli cells through binding of RARα to a novel DR5-RARE on Gdnf promoter. Pharmacological inhibition and chromatin immunoprecipitation-quantitative polymerase chain reaction analysis suggested that the underlying mechanism involved histone deacetylase activity and epigenetic repression of Gdnf promoter upon RA treatment.

TNF-α inhibits GDNF levels in Sertoli cells, through a NF-κB-dependent, HES1-dependent mechanism.

BACKGROUND: Glial cell line-derived neurotrophic factor (GDNF) is a soluble molecule crucial for the regulation of the spermatogonial stem cells (SSC) of the testis. The effects of GDNF on target cells have been extensively described, but mechanisms underlying GDNF regulation are currently under investigation. In the nervous system, GDNF expression is regulated by pro-inflammatory cytokines including lipopolysaccharide (LPS), interleukin 1 beta (IL-1ß), and tumor necrosis factor alpha (TNF-α) but the effect of these cytokines on GDNF expression in the testis is unclear. OBJECTIVES: The aim of the present study was to investigate the impact of TNF-α on GDNF expression levels using primary murine Sertoli cells as experimental model. MATERIAL AND METHODS: The expression of TNF-α-regulated genes including Gdnf in different culture conditions was determined by real-time PCR. GDNF protein levels were determined by ELISA. The activation of the NF-κb pathway and HES1 levels were assessed by Western Blot analysis and immunofluorescence. HES1 expression was downregulated by RNAi. RESULTS: In primary Sertoli cells, TNF-α downregulates GDNF levels through a nuclear factor-κB (NF-κB)-dependent mechanism. Mechanistically, TNF-α induces the transcriptional repressor HES1 by a NF-Κb-dependent mechanism, which in turn downregulates GDNF. DISCUSSION: Under physiological conditions, TNF-α is secreted by germ cells suggesting that this cytokine plays a role in the paracrine control of SSC niche by modulating GDNF levels. HES1, a well-known target of the Notch pathway, is implicated in the regulation of GDNF expression. In Sertoli cells, TNF-α and Notch signaling may converge at molecular level, to regulate the expression of HES1 and HES1- target genes, including GDNF. CONCLUSIONS: Because of the importance of GDNF for spermatogonial stem cell self-renewal and proliferation, this data may give important insights on how cytokine signals in the testis modulate the expression of niche-derived factors.

New Perspectives in Glioblastoma: Nanoparticles-based Approaches.

Glioblastoma multiforme represents one of the most aggressive tumor of central nervous system. Current therapy includes surgery, radiation and chemotherapy. These treatments are rarely curative and glioma are associated with a poor prognosis. Nanomedicine represents the most innovative branch of medicine since many studies demonstrated great advantage in the diagnosis and therapy of several diseases. In this review we will summarize the results obtained by the use of nanoparticles and extracellular vesicles in glioblastoma. A great interest is raising from these studies that underlined the efficacy and specificity of this treatment for glioma, reducing side-effects associated with conventional therapies.

Nanoparticles-Based Treatment for Bone Metastasis.

Bone is the principal site of metastasis for many carcinomas, including prostate. Once bone metastases are established, the chances of survival dramatically drop. Bone metastases place patients at increased risk of skeletal-related events, including pathologic fractures, bone pain and hypercalcemia. Indeed, skeletal metastases represent the prevalent cause of morbidity and mortality for many tumors. They are the result of interactions among tumour cells, bone marrow environment and bone cells (vicious cycle). In the last few years many efforts were undertaken to identify new therapeutic approaches for bone metastasis. Current therapies target the several players of bone vicious cycle. However many adverse effects are associated with these treatments. This review will focus on the new emerging sector of nanomedicine, that could be important to identify more specific and safe treatments for bone metastasis.

Differential effects of extracellular vesicles secreted by mesenchymal stem cells from different sources on glioblastoma cells.

BACKGROUND: Malignant glial tumors, including glioblastoma multiforme, account for 15 - 20% of pediatric CNS malignancies. They are most resistant to therapy and are associated with a poor prognosis. OBJECTIVE: Given the ability of mesenchymal stem cells (MSCs) to affect glioma growth, we investigated the effects of extracellular vesicles (EVs) derived from MSCs on U87MG glioblastoma cells line. METHODS: EVs were isolated from culture media of MSCs from different sources, including bone marrow (BM), umbilical cord (UC) and adipose tissue (AT) and added to U87MG culture. The internalization and the effects of BM-, UC- and AT-MSC-EVs on proliferation and apoptosis of tumor cells were evaluated. RESULTS: Both confocal microscopy and FACS analysis showed internalization of EVs into tumor cells. BM- and UC-MSC-EVs decreased cell proliferation, while an opposite effect was observed with AT-MSC-EVs. Moreover, both BM- and UC-MSC-EVs induced apoptosis of glioblastoma cells, while AT-MSC-EVs had no effect. Loading UC-MSC-EVs with Vincristine further increased cytotoxicity when compared both to the free drug and to untreated EVs. CONCLUSIONS: Different effects of MSC-EVs on cancer cells were observed depending on their tissue of origin. Moreover, MSC-EVs can deliver antiblastic drugs to glioblastoma cells.