Evaluation of neural markers expression in human mesenchymal stem cells after mesengenic differentiation

Introduction. Mesenchymal Stem Cells (MSCs) are adult multipotent cells able to differentiate in mesengenic (osteogenic, adipogenic, condrogenic) and non mesengenic lineages (e.g. neural) under appropriate culture conditions. MSCs represent a very promising therapeutic approach in different settings particularly for tissue repair and regeneration. The knowledge of human MSCs (hMSCs) biological properties is very important to optimize their clinical application. In view of MSCs application in neurodegenerative diseases, the neuronal differentiation potential of hMSCs has been also explored. Our preliminary data demonstrated that the neuronal markers beta III tubulin and NeuN were spontaneously expressed by a high percentage of undifferentiated hMSCs independently from serum presence and number of culture passages. The expression of neural markers by MSCs in absence of any differentiative agents is considered as a demonstration of MSC neural predisposition. The aim of this work was to evaluate if these markers, known to be neuronal ones, continued to be expressed also in hMSCs differentiated towards mesengenic lineages. Methods. hMSCs were obtained after patient consensus, from iliac crest bone marrow. In according to the Mesenchymal and Tissue Stem Cell Committee of the International Society for Cellular Therapy, the isolated hMSCs were plastic-adherent, capable of extensive proliferation when maintained in standard culture conditions, lacked of hematopoietic markers expression and presented specific surface antigens. hMSCs were differentiated toward osteogenic, adipogenic and chondrogenic lineages using specific in vitro protocols. The expression of the neuronal markers beta III tubulin and NeuN were evaluated by immunofluorescence experiments at different time points depending on the differentiation protocol used. hMSCs cultured in absence of any differentiative agent represented controls. Results. In our experiments the most of hMSCs differentiated in osteogenic and adipogenic lineages expressed the neuronal markers beta III tubulin and NeuN. Unlike, chondrogenic differentiated hMSCs didn’t express these markers. Conclusions. The finding that hMSCs differentiated into adipogenic and osteogenic lineages express neuronal markers such as beta III tubulin  and NeuN raises doubts about the reliability of these markers as indicators of neuronal differentiation and suggests that their expression could be an intrinsic property of a wide range of cellular types. Further studies are necessary to understand the specific biological role of of beta III tubulin and NeuN in hMSCs differentiated towards mesengenic lineages

Antitumoral effects of Hibiscus sabdarifa on human oral squamous cell carcinoma and multiple myeloma cells

Epidemiological data consistently demonstrate a reduced cancer risk associated with a polyphenols rich diet. Hibiscus sabdarifa (HS), a polyphenols rich plant widely consumed worldwide as beverage and used in folk medicine, has recently gained interest thanks to its antioxidant, anti-inflammatory and chemopreventive properties. In the present study we investigated the antitumoral potential of HS extract in two different human tumor cell lines: Multiple Myeloma cells (RPMI 8226) and Oral Squamous Cell Carcinoma cells (SCC-25). MTT assays showed that HS extract induced a dose-dependent viability reduction in both the cells lines. For the subsequent experiments we used HS at the concentration of 5 mg/ml that was the most effective in inducing cell viability reduction after 48h of treatment. Viable cell count using trypan blue staining demonstrated that the HS extract induced decrease in cell growth of both the cell lines and this was due to a reversible cytostatic rather than a cytotoxic effect. Wound-healing and cell invasion assays, respectively performed by a scratch of cell monolayer and Boyden Chamber transwell test, demonstrated that HS extract was able to reduce motility and invasiveness in both RPMI 8226 and SCC-25 cells. The chemical inhibition of ERK1/ERK2 and PI3K, with U0126 and wortmannin respectively, reduces proliferation and migration of both SSC-25 and RPMI cells and HB extract treatment played an additive action with the inhibitors. In conclusion, our results suggest that HS extract have antitumoral properties, since it proved to inhibit tumoral cell growth and cell migration and invasiveness. It is interesting to note that HS extract is effective against two very different tumor cell lines. In fact, RPMI 8226 cells are of hematopoietic origin and grow in suspension, whereas SCC-25 cells derive from epithelium and are characterized by adherent cell growth. Therefore, although further studies are needed to clarify the molecular mechanisms involved in its action, we proposed HS as a potential chemopreventive agent

Monitoring the genomic stability of in vitro cultured rat bone-marrow-derived mesenchymal stem cells

Bone-marrow-derived mesenchymal stem cells (MSCs) are multipotent cells capable of self-renewal and differentiation into multiple cell types. Accumulating preclinical and clinical evidence indicates that MSCs are good candidates to use as cell therapy in many degenerative diseases. For MSC clinical applications, an adequate number of cells are necessary so an extensive expansion is required. However, spontaneous immortalization and malignant transformation of MSCs after culture expansion have been reported in human and mouse, while very few data are present for rat MSCs (rMSCs). In this study, we monitored the chromosomal status of rMSCs at several passages in vitro, also testing the influence of four different cell culture conditions. We first used the conventional traditional cytogenetic techniques, in order to have the opportunity to observe even minor structural abnormalities and to identify low-degree mosaic conditions. Then, a more detailed genomic analysis was conducted by array comparative genomic hybridization. We demonstrated that, irrespective of culture conditions, rMSCs manifested a markedly aneuploid karyotype and a progressive chromosomal instability in all the passages we analyzed and that they are anything but stable during in vitro culture. Despite the fact that the risk of neoplastic transformation associated with this genomic instability needs to be further addressed and considering the apparent genomic stability reported for in vitro cultured human MSCs (hMSCs), our findings underline the fact that rMSCs may not in fact be a good model for effectively exploring the full clinical therapeutic potential of hMSCs

Mesenchymal stem cells enhance GABAergic transmission in co-cultured hippocampal neurons

Bone marrow-derived mesenchymal stem cells (MSCs) are multipotent stem cells endowed with neurotrophic potential combined with immunological properties, making them a promising therapeutic tool for neurodegenerative disorders. However, the mechanisms through which MSCs promote the neurological recovery following injury or inflammation are still largely unknown, although cell replacement and paracrine mechanisms have been hypothesized. In order to find out what are the mechanisms of the trophic action of MSCs, as compared to glial cells, on CNS neurons, we set up a co-culture system where rat MSCs (or cortical astrocytes) were used as a feeding layer for hippocampal neurons without any direct contact between the two cell types. The analysis of hippocampal synaptogenesis, synaptic vesicle recycling and electrical activity show that MSCs were capable to support morphological and functional neuronal differentiation. The proliferation of hippocampal glial cells induced by the release of bioactive substance(s) from MSCs was necessary for neuronal survival. Furthermore, MSCs selectively increased hippocampal GABAergic pre-synapses. This effect was paralleled with a higher expression of the potassium/chloride KCC2 co-transporter and increased frequency and amplitude of mIPSCs and sIPSCs. The enhancement of GABA synapses was impaired by the treatment with K252a, a Trk/neurotrophin receptor blocker, and by TrkB receptor bodies hence suggesting the involvement of BDNF as a mediator of such effects. The results obtained here indicate that MSC-secreted factors induce glial-dependent neuronal survival and trigger an augmented GABAergic transmission in hippocampal cultures, highlighting a new effect by which MSCs could promote CNS repair. Our results suggest that MSCs may be useful in those neurological disorders characterized by an impairment of excitation versus inhibition balance

Evaluation of tubulin polymerization and chronic inhibition of proteasome as citotoxicity mechanisms in bortezomib-induced peripheral neuropathy

Bortezomib (BTZ) is the first proteasome inhibitor entered in clinical practice. Peripheral neuropathy is likely to be a class side effect of these drugs, although its severity is largely variable, and it deserves to be further investigated, since the mechanisms of BTZ-induced peripheral neurotoxicity (BiPN) are still unknown.   In our study, we investigated in vivo and in vitro possible pathogenic events relevant to BiPN using a well-established rat model, with particular reference to the extent of proteasome inhibition and the effects on α-tubulin polymerization in sciatic nerves and dorsal root ganglia specimens obtained from animals treated with chronic regimens at a dose of 0.2 mg/kg intravenously. The same assessments were also performed after a single injection. Moreover, these studies were replicated in vitro using embryonic DRG neurons exposed to 100 nM BTZ and adult DRG neurons exposed to 10-50 nM BTZ for 24 h and 48 h. A significant increase in the polymerized fraction of α-tubulin and prolonged proteasome inhibition were observed after the chronic BTZ treatment in vivo. Recovery to physiological levels was observed after a 4-week follow-up post-treatment period. Proteasome inhibition and increased α-tubulin polymerization were also observed following BTZ treatment of both embryonic and adult DRG neurons in vitro. Our in vivo results suggest that proteasome inhibition and alteration of tubulin dynamics contribute to BiPN. The in vitro systems here described reliably replicate the in vivo results, and might therefore be used for further mechanistic studies on the effects of proteasome inhibitors on neurons