Tumor cell behaviour modulation by mesenchymal stromal cells

BACKGROUND: Human mesenchymal stromal cells (MSC) hold a promise for future cell-based therapies due to their immunomodulatory properties and/or secretory activity. Nevertheless non-neoplastic tumor compartment could also originate from MSC. We aimed to show whether multipotent MSC derived from human adipose tissue (AT-MSC) could create tumor cell-protective milieu and affect tumor cell behaviour in vitro and in vivo. RESULTS: Here we have demonstrated tumor-promoting effect of AT-MSC on human melanoma A375 cells. AT-MSC coinjection mediated abrogation of tumor latency and supported subcutaneous xenotransplant growth from very low melanoma cell doses. Tumor incidence was also significantly increased by AT-MSC-derived soluble factors. AT-MSC supported proliferation, suppressed apoptosis and modulated melanoma cell responses to cytotoxic drugs in vitro. Expression and multiplex cytokine assays confirmed synergistic increase in VEGF that contributed to the AT-MSC-mediated support of A375 xenotransplant growth. Production of G-CSF and other factors implicated in formation of supportive proinflammatory tumor cell microenvironment was also confirmed. SDF-1α/CXCR4 signalling contributed to tumor-promoting effect of systemic AT-MSC administration on A375 xenotransplants. However, no support was observed for human glioblastoma cells 8MGBA co-injected along with AT-MSC that did not sustain tumor xenotransplant growth in vivo. Tumor-inhibiting response could be attributed to the synergistic action of multiple cytokines produced by AT-MSC on glioblastoma cells. CONCLUSIONS: Herein we provide experimental evidence for MSC-mediated protective effect on melanoma A375 cells under nutrient-limiting and hostile environmental conditions resulting from mutual crosstalk between neoplastic and non-malignant cells. This tumor-favouring effect was not observed for the glioblastoma cells 8MGBA. Collectively, our data further strengthen the need for unravelling mechanisms underlying MSC-mediated modulation of tumor behaviour for possible future MSC clinical use in the context of malignant disease

Low-Dose-Rate Irradiation for 1 Hour Induces Protection Against Lethal Radiation Doses but Does Not Affect Life Span of DBA/2 Mice

Prior findings showed that serum from DBA/2 mice that had been given whole-body irradiation for 1 hour at a low dose rate (LDR) of 30 cGy/h induced protection against radiation in reporter cells by a mechanism depending on transforming growth factor β3 and inducible nitric oxide synthase activity. In the present study, the effect of the 1 hour of LDR irradiation on the response of the preirradiated mice to a subsequent lethal dose and on the life span is examined. These DBA/2 mice were prime irradiated for 1 hour at 30 cGy/h. Two experiments with 9 and 9.5 Gy challenge doses given 6 weeks after priming showed increased survival in primed mice compared to unprimed mice followed up to 225 and 81 days after challenge irradiation, respectively. There was no overall significant difference in life span between primed and unprimed mice when no challenge irradiation was given. The males seemed to have a slight increase in lifespan after priming while the opposite was seen for the females

Characterization of mesenchymal stem cells of "no-options" patients with critical limb ischemia treated by autologous bone marrow mononuclear cells.

Application of autologous bone marrow mononuclear cells to "no option" patients with advanced critical limb ischemia (CLI) prevented major limb amputation in 73% patients during the 6-month follow-up. We examined which properties of bone marrow stromal cells also known as bone-marrow derived mesenchymal stem cells of responding and non-responding patients are important for amputation-free survival.Mesenchymal stem cells of 41 patients with CLI unsuitable for revascularisation were isolated from mononuclear bone marrow concentrate used for their treatment. Based on the clinical outcome of the treatment, we divided patients into two groups: responders and non-responders. Biological properties of responders' and non-responders' mesenchymal stem cells were characterized according to their ability to multiply, to differentiate in vitro, quantitative expression of cell surface markers, secretion of 27 cytokines, chemokines and growth factors, and to the relative expression of 15 mesenchymal stem cells important genes. Secretome comparison between responders (n=27) and non-responders (n=14) revealed significantly higher secretion values of IL-4, IL-6 and MIP-1b in the group of responders. The expression of cell markers CD44 and CD90 in mesenchymal stem cells from responders was significantly higher compared to non-responders (p<0.01). The expression of mesenchymal stem cells surface markers that was analyzed in 22 patients did not differ between diabetic (n=13) and non-diabetic (n=9) patient groups. Statistically significant higher expression of E-cadherin and PDX-1/IPF1 genes was found in non-responders, while expression of Snail was higher in responders.The quality of mesenchymal stem cells shown in the expression of cell surface markers, secreted factors and stem cell genes plays an important role in therapeutic outcome. Paracrine mechanisms are main drivers in the induction of reparatory processes in CLI patients. Differences in mesenchymal stem cells properties are discussed in relation to their involvement in the reparatory process

Secretion of factors from MSCs and gene expression.

<p>(<b>A</b>) Secretome comparison of several factors of responders (n=27) and non-responders (n=14) CLI patients; For detection of cytokines, chemokines and growth factors Bio-Plex Pro Human Cytokine 27-plex Assay from Bio-Rad was used. The concentration of each factor was calculated per mg of total proteins in 24 hour conditioned medium. The values of growth factors detected in control medium were deducted from values found in conditioned medium. (B) Relative expression of 15 genes typical for MSCs on the level of proteins. Cell extracts of MSCs in early passage of seven non-responders and eight responders were examined by Proteome Profiler Human Pluripotent Stem Cell Array.</p

Doubling time of continually cultivated MSCs from CLI patients in comparison to healthy young donor.

<p>(<b>A</b>) Ability of MSCs of CLI patient to differentiate to osteogenic, adipogenic and chondrogenic lineages; (<b>B</b>) Doubling time of MSCs of CLI patients in first passage. The value is an average of two independent estimations; (<b>C</b>) Doubling time of continually cultivated MSCs from four CLI patients in comparison to healthy young donor. Lines represent the trend.</p

Expression of cell surface markers characterizing MSCs.

<p>(A) Expression of MSCs markers on the surface of mesenchymal stem cells of group of responders versus non responders (** - statistic significance is ≤ 0.01; * - statistic significance is ≤ 0.02). (B) Expression of MSCs markers on the surface of mesenchymal stem cells of group of diabetic patients (n=13) versus non diabetic (n=9).</p