Mesenchymal stem cells directly interact with breast cancer cells and promote tumor cell growth in vitro and in vivo

Human mesenchymal stroma/stem cells exchange membrane proteins and alter functionality during interaction with different tumor cell lines

To analyze effects of cellular interaction between human mesenchymal stroma/stem cells (MSC) and different cancer cells, direct co-cultures were performed and revealed significant growth stimulation of the tumor populations and a variety of protein exchanges. More than 90% of MCF-7 and primary human HBCEC699 breast cancer cells as well as NIH:OVCAR-3 ovarian adenocarcinoma cells acquired CD90 proteins during MSC co-culture, respectively. Furthermore, SK-OV-3 ovarian cancer cells progressively elevated CD105 and CD90 proteins in co-culture with MSC. Primary small cell hypercalcemic ovarian carcinoma cells (SCCOHT-1) demonstrated undetectable levels of CD73 and CD105; however, both proteins were significantly increased in the presence of MSC. This co-culture-mediated protein induction was also observed at transcriptional levels and changed functionality of SCCOHT-1 cells by an acquired capability to metabolize 5'cAMP. Moreover, exchange between tumor cells and MSC worked bidirectional, as undetectable expression of epithelial cell adhesion molecule (EpCAM) in MSC significantly increased after co-culture with SK-OV-3 or NIH:OVCAR-3 cells. In addition, a small population of chimeric/hybrid cells appeared in each MSC/tumor cell co-culture by spontaneous cell fusion. Immune fluorescence demonstrated nanotube structures and exosomes between MSC and tumor cells, whereas cytochalasin-D partially abolished the intercellular protein transfer. More detailed functional analysis of FACS-separated MSC and NIH:OVCAR-3 cells after co-culture revealed the acquisition of epithelial cell-specific properties by MSC, including increased gene expression for cytokeratins and epithelial-like differentiation factors. Vice versa, a variety of transcriptional regulatory genes were down-modulated in NIH:OVCAR-3 cells after co-culture with MSC. Together, these mutual cellular interactions contributed to functional alterations in MSC and tumor cells.

Mesenchymal stem cell-mediated suppression of hypertrophic scarring is p53 dependent in a rabbit ear model

Introduction

Mesenchymal stem cells (MSCs) are considered to play important roles in wound repair and tissue remodeling. Hypertrophic scar (HTS) is a cutaneous condition characterized by deposits of excessive amount of collagen after an acute skin injury. However, currently there is little knowledge about the direct relationship between MSCs and HTS.

Methods

The hypertrophic scar model was established on rabbit ears. MSCs were isolated from rabbit femur bone marrow and transplanted through ear artery injection. Hypertrophic scar formation was examined using frozen-section analysis, hematoxylin and eosin (HE) staining, Masson’s trichrome staining, and scar elevation index. The role of p53 in the MSCs-mediated anti-scarring effect was examined by gene knockdown using p53 shRNA.

Results

In this study, MSCs engraftment through ear artery injection significantly inhibited the hypertrophic scarring in a rabbit ear hypertrophic scar model, while this anti-scarring function could be abrogated by p53 gene knockdown in MSCs. Additionally, we found that MSCs down-regulated the expression of TGF-β receptor I (TβRI) and alpha-smooth muscle actin (α-SMA) at both mRNA and protein levels in a paracrine manner, and this down-regulation was rescued by p53 gene knockdown. Moreover, our results showed that MSCs with p53 gene knockdown promoted the proliferation of fibroblasts through increasing nitric oxide (NO) production.

Conclusions

These results suggest that MSCs inhibit the formation of HTS in a p53 dependent manner through at least two mechanisms: inhibition of the transformation of HTS fibroblast to myofibroblast; and inhibition of the proliferation of fibroblasts through inhibition of NO production.

Cell recruitment by amnion chorion grafts promotes neovascularization

BACKGROUND

Nonhealing wounds are a significant health burden. Stem and progenitor cells can accelerate wound repair and regeneration. Human amniotic membrane has demonstrated efficacy in promoting wound healing, though the underlying mechanisms remain unknown. A dehydrated human amnion chorion membrane (dHACM) was tested for its ability to recruit hematopoietic progenitor cells to a surgically implanted graft in a murine model of cutaneous ischemia.

METHODS

dHACM was subcutaneously implanted under elevated skin (ischemic stimulus) in either wild-type mice or mice surgically parabiosed to green fluorescent protein (GFP) + reporter mice. A control acellular dermal matrix, elevated skin without an implant, and normal unwounded skin were used as controls. Wound tissue was harvested and processed for histology and flow cytometric analysis.

RESULTS

Implanted dHACMs recruited significantly more progenitor cells compared with controls (*P < 0.05) and displayed in vivo SDF-1 expression with incorporation of CD34 + progenitor cells within the matrix. Parabiosis modeling confirmed the circulatory origin of recruited cells, which coexpressed progenitor cell markers and were localized to foci of neovascularization within implanted matrices.

CONCLUSIONS

In summary, dHACM effectively recruits circulating progenitor cells, likely because of stromal derived factor 1 (SDF-1) expression. The recruited cells express markers of "stemness" and localize to sites of neovascularization, providing a partial mechanism for the clinical efficacy of human amniotic membrane in the treatment of chronic wounds.

Adult adipose-derived stem cells and breast cancer: a controversial relationship

Breast cancer is the most common cancer in women and autologous fat grafting is an important clinical application in treatment of post-surgical deformities. The simplicity of fat grafting procedures and the absence of subsequent visible scar prompted an increasing interest for this technique. The plasticity of adipose-derived stem cells (ASCs) obtained from stromal vascular fraction (SVF) of adult adipose tissue provided exciting perspectives for regenerative medicine and surgery. The recent discovery that SVF/ASC enrichment further ameliorates clinical efficacy of grafting ASCs suggest as ASC-mediated new adipogenesis and vasculogenesis. ASC adipogenic differentiation involves Akt activity and EGFRs, FGFRs, ERbB2 receptor-mediated pathways that also play a pivotal role in the regulation of breast cancer growth. Moreover, the finding that platelet-derived growth factors and hormones improved long-term maintenance of fat grafting raises new concerns for their use during breast reconstruction after cancer surgery. However, it remains unclear whether grafted or resident ASCs may increase the risk of de novo cancer development or recurrence. Preliminary follow-up studies seem to support the efficacy and safety of SVF/ASCs enrichment and the additional benefit from the combined use of autologous platelet-derived growth factors and hormones during breast reconstruction procedures. In the present review we highlighted the complex interplay between resident or grafted ASCs, mature adipocytes, dormant or active breast cancer cells and tumor microenvironment. Actually, data concerning the permissive role of ASCs on breast cancer progression are contrasting, although no clear evidence speaking against their use exists.

Interference of Ca²⁺ with the proliferation of SCCOHT-1 and ovarian adenocarcinoma cells

A recently established cellular model for the rare small cell carcinoma of the ovary hypercalcemic type (SCCOHT-1) was characterized in comparison to ovarian adenocarcinoma cells (NIH:OVCAR-3 and SK-OV-3). The different cancer populations exhibited a common sensitivity in acidic pH milieu and a continuous proliferation in alkaline medium of pH 8.0-9.0. In the presence of elevated Ca2+ concentrations, the ovarian cancer cells demonstrated a progressively reduced proliferation within 72 h in contrast to other tumor types such as breast cancer cells. This significant growth inhibition was calcium-specific since the proliferation was unaffected after culture of the ovarian cancer cells in the presence of similar concentrations of other cations. The Ca2+ effects on the ovarian cancer cells were associated with marked differences in the activation of intracellular signaling pathways including enhanced phosphorylation of the p42/44 MAP kinase (Thr202/Tyr204). Further analysis of the signaling pathway revealed a significantly enhanced Ca2+-dependent and p42/44 MAP kinase activation-mediated prostaglandin E2 (PGE2) production in SK-OV-3 and SCCOHT-1 and to a lesser extent in NIH:OVCAR-3 cells. Vice versa, exogenous PGE2 did not affect the proliferative capacity of the ovarian cancer cells and inhibition of the Ca2+-mediated MAP kinase activation did not abolish the Ca2+-mediated cytotoxicity. Collectively, these data suggest that multiple pathways are activated by exogenous Ca2+ in the different ovarian cancer cells, including a specific MAP kinase signaling cascade with subsequent PGE2 production and a parallel pathway for the induction of cell death.

Umbilical cord mesenchymal stem cells: the new gold standard for mesenchymal stem cell-based therapies?

Due to their self-renewal capacity, multilineage differentiation potential, paracrine effects, and immunosuppressive properties, mesenchymal stromal cells (MSCs) are an attractive and promising tool for regenerative medicine. MSCs can be isolated from various tissues but despite their common immunophenotypic characteristics and functional properties, source-dependent differences in MSCs properties have recently emerged and lead to different clinical applications. Considered for a long time as a medical waste, umbilical cord appears these days as a promising source of MSCs. Several reports have shown that umbilical cord-derived MSCs are more primitive, proliferative, and immunosuppressive than their adult counterparts. In this review, we aim at synthesizing the differences between umbilical cord MSCs and MSCs from other sources (bone marrow, adipose tissue, periodontal ligament, dental pulp,…) with regard to their proliferation capacity, proteic and transcriptomic profiles, and their secretome involved in their regenerative, homing, and immunomodulatory capacities. Although umbilical cord MSCs are until now not particularly used as an MSC source in clinical practice, accumulating evidence shows that they may have a therapeutic advantage to treat several diseases, especially autoimmune and neurodegenerative diseases.

Mechanisms of T-cell immunosuppression by mesenchymal stromal cells: what do we know so far?

Mesenchymal stromal cells (MSCs) are multipotent cells, which can give rise to several cell types including osteoblasts, adipocytes, and chondroblasts. These cells can be found in a variety of adult and fetal tissues, such as bone marrow, adipose tissue, cord blood, and placenta. In recent years, the biological properties of MSCs have attracted the attention of researchers worldwide due to their potential application for treating a series of clinical situations. Among these properties, special attention should be given to the immunoregulatory potential of those cells. MSCs are able to act on all cells of the immune system, which includes the capacity to inhibit the proliferation and function of T-cells. This feature renders them natural candidates to treat several diseases in which cellular immune response is exacerbated. In this review, we outline the main mechanisms by which MSCs immunosuppress T-cell response, focusing on cell-cell contact, secretion of soluble factors, and regulatory T-cell generation. The influence of surface markers in the immunosuppression process and features of MSCs isolated from different sources are also discussed. Finally, the influences of toll-like receptors and cytokines on the inflammatory microenvironment are highlighted regarding the activation of MSCs to exert their immunoregulatory function.