Concise review: adult multipotent stromal cells and cancer: risk or benefit?

Cultured Meat in Islamic Perspective

Cultured meat is a promising product that is derived through biotechnology that partially circumvents animal physiology, thereby being potentially more sustainable, environmentally friendly and animal friendly than traditional livestock meat. Such a novel technology that can impact many consumers evokes ethical, philosophical and religious discussions. For the Islamic community, the crucial question is whether cultured meat is halal, meaning compliant with Islamic laws. Since the culturing of meat is a new discovery, invention and innovation by scientists that has never been discussed by classical jurists (fuqaha'), an ijtihad by contemporary jurists must look for and provide answers for every technology introduced, whether it comply the requirements of Islamic law or not. So, this article will discuss an Islamic perspective on cultured meat based on the original scripture in the Qur'an and interpretations by authoritative Islamic jurists. The halal status of cultured meat can be resolve through identifying the source cell and culture medium used in culturing the meat. The halal cultured meat can be obtained if the stem cell is extracted from a (Halal) slaughtered animal, and no blood or serum is used in the process. The impact of this innovation will give positive results in the environmental and sustain the livestock industry.

Hypoxia-Induced Damage in Human Islets Is Reduced With the Use of Mesenchymal Stem Cell-Preconditioned Medium

BACKGROUND

Mesenchymal stem cells (MSCs) are protective for islets when cotransplanted in a hypoxic environment. However, the risk of neoplasia is increased when MSCs are transplanted into immunosuppressed patients. This initial study aimed to investigate whether the production of protective factors from MSC can be stimulated by different culture conditions to benefit human islets cultured in hypoxia.

METHODS

MSC were isolated from human adipose tissue and cultured for 2 days in supplemented Minimum Essential Media α (MEMα) and 21% (21%-MEMα) or 1% oxygen (1%-MEMα). Native MEMα served as control. After MSC harvesting, cell-depleted media were frozen at -20°C until use for human islet culture in 2% oxygen for 72-96 hours before islet characterization. Data were normalized to control islets cultured in native MEMα and 2% oxygen (mean ± SEM).

RESULTS

After culture in 21%- or 1%-MEMα, islet recovery increased to 117 ± 12% (NS) and 138 ± 12% (P < .05), respectively. Viability did not change after culture in native MEMα (59 ± 2%), 21%-MEMα (59 ± 3%), or 1%-MEMα (61 ± 3%). Compared with control samples, the glucose stimulation index was increased after culture in 21%-MEMα (P < .05) or 1%-MEMα (P < .05). Overall survival was higher in 1%-MEMα (143 ± 14%) than in 21%-MEMα (119 ± 14%; NS) or native MEMα (P < .05).

CONCLUSIONS

This study demonstrates that MSC-preconditioned MEMα increases survival and in vitro function of hypoxic human islets. These findings indicate that hypoxic MSCs seem to produce factors that improve survival of islets suffering from hypoxia.

Targeting the Epidermal Growth Factor Receptor Can Counteract the Inhibition of Natural Killer Cell Function Exerted by Colorectal Tumor-Associated Fibroblasts

Mesenchymal stromal cells (MSC) present in the tumor microenvironment [usually named tumor-associated fibroblasts (TAF)] can exert immunosuppressive effects on T and natural killer (NK) lymphocytes, favoring tumor immune escape. We have analyzed this mechanism in colorectal carcinoma (CRC) and found that co-culture of NK cells with TAF can prevent the IL-2-mediated NKG2D upregulation. This leads to the impairment of NKG2D-mediated recognition of CRC cells, sparing the NK cell activation through DNAM1 or FcγRIIIA (CD16). In situ, TAF express detectable levels of epidermal growth factor receptor (EGFR); thus, the therapeutic anti-EGFR humanized antibody cetuximab can trigger the antibody-dependent cellular cytotoxicity of TAF, through the engagement of FcγRIIIA on NK cells. Importantly, in the tumor, we found a lymphoid infiltrate containing NKp46⁺CD3^- NK cells, enriched in CD16⁺ cells. This population, sorted and cultured with IL-2, could be triggered via CD16 and via NKG2D. Of note, ex vivo NKp46⁺CD3^- cells were able to kill autologous TAF; in vivo, this might represent a control mechanism to reduce TAF-mediated regulatory effect on NK cell function. Altogether, these findings suggest that MSC from the neoplastic mucosa (TAF) of CRC patients can downregulate the immune cell recognition of CRC tumor cells. This immunosuppression can be relieved by the anti-EGFR antibody used in CRC immunotherapy.

The multifaceted role of exosomes in cancer progression: diagnostic and therapeutic implications [corrected]

BACKGROUND

Recent advances in cancer biology have highlighted the relevance of exosomes and nanovesicles as carriers of genetic and biological messages between cancer cells and their immediate and/or distant environments. It has been found that these molecular cues may play significant roles in cancer progression and metastasis. Cancer cells secrete exosomes containing diverse molecules that can be transferred to recipient cells and/or vice versa to induce a plethora of biological processes, including angiogenesis, metastasis formation, therapeutic resistance, epithelial-mesenchymal transition and epigenetic/stemness (re)programming. While exosomes interact with cells within the tumour microenvironment to promote tumour growth, these vesicles can also facilitate the process of distant metastasis by mediating the formation of pre-metastatic niches. Next to their tumour promoting effects, exosomes have been found to serve as potential tools for cancer diagnosis and therapy. The ease of isolating exosomes and their content from different body fluids has led to the identification of diagnostic and prognostic biomarker signatures, as well as to predictive biomarker signatures for therapeutic responses. Exosomes can also be used as cargos to deliver therapeutic anti-cancer drugs, and they can be engineered to serve as vaccines for immunotherapy. Additionally, it has been found that inhibition of exosome secretion, and thus the transfer of oncogenic molecules, holds promise for inhibiting tumour growth. Here we provide recent information on the diverse roles of exosomes in various cellular and systemic processes governing cancer progression, and discuss novel strategies to halt this progression using exosome-based targeted therapies and methods to inhibit exosome secretion and the transfer of pro-tumorigenic molecules.

CONCLUSIONS

This review highlights the important role of exosomes in cancer progression and its implications for (non-invasive) diagnostics and the development of novel therapeutic strategies, as well as its current and future applications in clinical trials.

miRNA-1246 induces pro-inflammatory responses in mesenchymal stem/stromal cells by regulating PKA and PP2A

The tumor microenvironment (TME) has an impact on breast cancer progression by creating a pro-inflammatory milieu within the tumor. However, little is known about the roles of miRNAs in cells of the TME during this process. We identified six putative oncomiRs in a breast cancer dataset, all strongly correlating with poor overall patient survival. Out of the six candidates, miR-1246 was upregulated in aggressive breast cancer subtypes and expressed at highest levels in mesenchymal stem/stroma cells (MSCs). Functionally, miR-1246 led to a p65-dependent increase in transcription and release of pro-inflammatory mediators IL-6, CCL2 and CCL5 in MSCs, and increased NF-κB activity. The pro-inflammatory phenotype of miR-1246 in MSCs was independent of TNFα stimulations and mediated by direct targeting of the tumor-suppressors PRKAR1A and PPP2CB. In vitro recapitulation of the TME revealed increased Stat3 phosphorylation in breast epithelial (MCF10A) and cancer cells (SK-BR-3, MCF7, T47D) upon incubation with conditioned medium (CM) of MSCs overexpressing miR-1246. Additionally, this stimulation enhanced proliferation of MCF10A cells, increased migration of MDA-MB-231 cells and induced attraction of THP-1 monocytic cells. Our data shows that miR-1246 acts as both key-enhancer of pro-inflammatory responses in MSCs and putative oncomiR in breast cancer, suggesting its influence on cancer-related inflammation and breast cancer progression.

How to Hit Mesenchymal Stromal Cells and Make the Tumor Microenvironment Immunostimulant Rather Than Immunosuppressive

Experimental evidence indicates that mesenchymal stromal cells (MSCs) may regulate tumor microenvironment (TME). It is conceivable that the interaction with MSC can influence neoplastic cell functional behavior, remodeling TME and generating a tumor cell niche that supports tissue neovascularization, tumor invasion and metastasization. In addition, MSC can release transforming growth factor-beta that is involved in the epithelial-mesenchymal transition of carcinoma cells; this transition is essential to give rise to aggressive tumor cells and favor cancer progression. Also, MSC can both affect the anti-tumor immune response and limit drug availability surrounding tumor cells, thus creating a sort of barrier. This mechanism, in principle, should limit tumor expansion but, on the contrary, often leads to the impairment of the immune system-mediated recognition of tumor cells. Furthermore, the cross-talk between MSC and anti-tumor lymphocytes of the innate and adaptive arms of the immune system strongly drives TME to become immunosuppressive. Indeed, MSC can trigger the generation of several types of regulatory cells which block immune response and eventually impair the elimination of tumor cells. Based on these considerations, it should be possible to favor the anti-tumor immune response acting on TME. First, we will review the molecular mechanisms involved in MSC-mediated regulation of immune response. Second, we will focus on the experimental data supporting that it is possible to convert TME from immunosuppressive to immunostimulant, specifically targeting MSC.

Ethical and Safety Issues of Stem Cell-Based Therapy

Results obtained from completed and on-going clinical studies indicate huge therapeutic potential of stem cell-based therapy in the treatment of degenerative, autoimmune and genetic disorders. However, clinical application of stem cells raises numerous ethical and safety concerns. In this review, we provide an overview of the most important ethical issues in stem cell therapy, as a contribution to the controversial debate about their clinical usage in regenerative and transplantation medicine. We describe ethical challenges regarding human embryonic stem cell (hESC) research, emphasizing that ethical dilemma involving the destruction of a human embryo is a major factor that may have limited the development of hESC-based clinical therapies. With previous derivation of induced pluripotent stem cells (iPSCs) this problem has been overcome, however current perspectives regarding clinical translation of iPSCs still remain. Unlimited differentiation potential of iPSCs which can be used in human reproductive cloning, as a risk for generation of genetically engineered human embryos and human-animal chimeras, is major ethical issue, while undesired differentiation and malignant transformation are major safety issues. Although clinical application of mesenchymal stem cells (MSCs) has shown beneficial effects in the therapy of autoimmune and chronic inflammatory diseases, the ability to promote tumor growth and metastasis and overestimated therapeutic potential of MSCs still provide concerns for the field of regenerative medicine. This review offers stem cell scientists, clinicians and patient's useful information and could be used as a starting point for more in-depth analysis of ethical and safety issues related to clinical application of stem cells.

Exosome and mesenchymal stem cell cross-talk in the tumor microenvironment

Mesenchymal stem cells (MSCs) are a major component of the tumor microenvironment (TME) and play a key role in promoting tumor progression. The tumor uses exosomes to co-opt MSCs and re-program their functional profile from normally trophic to pro-tumorigenic. These tumor-derived small vesicles called "TEX" carry and deliver a cargo rich in proteins and nucleic acids to MSCs. Upon interactions with surface receptors on MSCs and uptake of the exosome cargo by MSCs, molecular, transcriptional and translational changes occur that convert MSCs into producers of factors that are necessary for tumor growth and that also alter functions of non-tumor cells in the TME. The MSCs re-programmed by TEX become avid producers of their own exosomes that carry and deliver mRNA and miRNA species as well as molecular signals not only back to tumor cells, directly enhancing their growth, but also horizontally to fibroblasts, endothelial cells and immune cells in the TME, indirectly enhancing their pro-tumor functions. TEX-driven cross-talk of MSCs with immune cells blocks their anti-tumor activity and/or converts them into suppressor cells. MSCs re-programmed by TEX mediate pro-angiogenic activity and convert stromal cells into cancer-associated fibroblasts (CAFs). Although MSCs have a potential to exert anti-tumor activities, they largely provide service to the tumor using the multidirectional communication system established by exosomes in the TME. Future therapeutic options consider disruption of this complex vicious cycle by either molecular or gene-regulated silencing of pro-tumor effects mediated by MSCs in the TME.

Extracellular vesicles released from mesenchymal stromal cells stimulate bone growth in osteogenesis imperfecta

BACKGROUND

Systemic infusion of mesenchymal stromal cells (MSCs) has been shown to induce acute acceleration of growth velocity in children with osteogenesis imperfecta (OI) despite minimal engraftment of infused MSCs in bones. Using an animal model of OI we have previously shown that MSC infusion stimulates chondrocyte proliferation in the growth plate and that this enhanced proliferation is also observed with infusion of MSC conditioned medium in lieu of MSCs, suggesting that bone growth is due to trophic effects of MSCs. Here we sought to identify the trophic factor secreted by MSCs that mediates this therapeutic activity.

METHODS

To examine whether extracellular vesicles (EVs) released from MSCs have therapeutic activity, EVs were isolated from MSC conditioned medium by ultracentrifugation. To further characterize the trophic factor, RNA or microRNA (miRNA) within EVs was depleted by either ribonuclease (RNase) treatment or suppressing miRNA biogenesis in MSCs. The functional activity of these modified EVs was evaluated using an in vitro chondrocyte proliferation assay. Finally, bone growth was evaluated in an animal model of OI treated with EVs.

RESULTS

We found that infusion of MSC-derived EVs stimulated chondrocyte proliferation in the growth plate, resulting in improved bone growth in a mouse model of OI. However, infusion of neither RNase-treated EVs nor miRNA-depleted EVs enhanced chondrocyte proliferation.

CONCLUSION

MSCs exert therapeutic effects in OI by secreting EVs containing miRNA, and EV therapy has the potential to become a novel cell-free therapy for OI that will overcome some of the current limitations in MSC therapy.

Different Effects of Human Umbilical Cord Mesenchymal Stem Cells on Glioblastoma Stem Cells by Direct Cell Interaction or Via Released Soluble Factors

Glioblastoma (GBM), the most common primary brain tumor in adults, is an aggressive, fast-growing and highly vascularized tumor, characterized by extensive invasiveness and local recurrence. In GBM and other malignancies, cancer stem cells (CSCs) are believed to drive invasive tumor growth and recurrence, being responsible for radio- and chemo-therapy resistance. Mesenchymal stem cells (MSCs) are multipotent progenitors that exhibit tropism for tumor microenvironment mediated by cytokines, chemokines and growth factors. Initial studies proposed that MSCs might exert inhibitory effects on tumor development, although, to date, contrasting evidence has been provided. Different studies reported either MSC anti-tumor activity or their support to tumor growth. Here, we examined the effects of umbilical cord (UC)-MSCs on in vitro GBM-derived CSC growth, by direct cell-to-cell interaction or indirect modulation, via the release of soluble factors. We demonstrate that UC-MSCs and CSCs exhibit reciprocal tropism when co-cultured as 3D spheroids and their direct cell interaction reduces the proliferation of both cell types. Contrasting effects were obtained by UC-MSC released factors: CSCs, cultured in the presence of conditioned medium (CM) collected from UC-MSCs, increased proliferation rate through transient ERK1/2 and Akt phosphorylation/activation. Analysis of the profile of the cytokines released by UC-MSCs in the CM revealed a strong production of molecules involved in inflammation, angiogenesis, cell migration and proliferation, such as IL-8, GRO, ENA-78 and IL-6. Since CXC chemokine receptor 2 (CXCR2), a receptor shared by several of these ligands, is expressed in GBM CSCs, we evaluated its involvement in CSC proliferation induced by UC-MSC-CM. Using the CXCR2 antagonist SB225002, we observed a partial but statistically significant inhibition of CSC proliferation and migration induced by the UC-MSC-released cytokines. Conversely, CXCR2 blockade did not reduce the reciprocal tropism between CSCs and UC-MSCs grown as spheroids. In conclusion, we show that direct (cell-to-cell contact) or indirect (via the release of soluble factors) interactions between GBM CSCs and UC-MSCs in co-culture produce divergent effects on cell growth, invasion and migration, with the former mainly causing an inhibitory response and the latter a stimulatory one, involving a paracrine activation of CXCR2.

A niche that triggers aggressiveness within BRCA1-IRIS overexpressing triple negative tumors is supported by reciprocal interactions with the microenvironment

Production of metastasis capable precursors begins within the primary tumor. Here, we define the bidirectional interactions with stromal cells involved in promoting these precursors within BRCA1-IRIS (hereafter IRIS) overexpressing (IRISOE) TNBC tumors. We define an aggressiveness niche, functionally defined as the necrotic/hypoxic core of the tumor, in which metabolically stressed, hypoxic, and inflamed IRISOE TNBC cells secrete higher levels of cytokines, chemokines and growth factors. One cytokine; IL-1β attracts mesenchymal stem cells (MSCs) to the niche and activates them to secrete CXCL1 that entrains IRISOE cells to secrete higher levels of CCL2 and VEGF. CCL2 attracts macrophages (TAMs) to the niche and activates them to secrete S100A8, and VEGF attracts endothelial cells (ECs) and activates them to secrete IL-8. In concert, CXCL1, S100A8 and IL-8 entrain aggressiveness in IRISOE TNBC cells within the niche. Indeed, compared to IRISOE cells alone, tumors developed by co-injecting IRISOE cells admixed with MSCs (10:1) in athymic mice were bigger and more aggressive. They contained more TAMs and ECs, expressed higher-levels of basal, epithelial to mesenchymal transition, and stemness biomarkers, quickly progressed to lymph-node or visceral metastases, and were highly sensitive to the IL-1β inhibitor “Anakinra”. Our findings supported by human data show that breast cancer patients with high-levels of IL-1β, CXCL1, CCL2, S100A8, VEGF, and IL-8 would show worse clinical outcomes. Our findings argue that this cytokine set is a diagnostic biomarker for patients who may benefit from an IRIS inhibitor-based therapy, and is a blue print for translation of approaches to combining that therapy with inhibitors of these bidirectional interactions to overcome TNBC metastasis.

Mesenchymal stem cell-derived CCN2 promotes the proliferation, migration and invasion of human tongue squamous cell carcinoma cells

Recent studies have demonstrated that mesenchymal stem cells (MSC) exhibit a tropism to tumors and form the tumor stroma. In addition, we found that MSC can secrete different types of factors. However, the involvement of MSC‐derived factors in human tongue squamous cell carcinoma (TSCC) growth has not been clearly addressed. The CCN family includes multifunctional signaling molecules that affect the initiation and development events of various tumors. In our study, we report that CCN2/connective tissue growth factor (CTGF) was the most highly induced among the CCN family members in MSC that were co‐cultured with TSCC cells. To evaluate the relationship between CCN2 and TSCC growth, we downregulated MSC‐derived CCN2 expression with shRNA targeting CCN2 and found that MSC‐secreted CCN2 promotes TSCC cell proliferation, migration and invasion. We also confirmed that MSC‐derived CCN2 partially accelerated tumor growth in vitro. Taken together, these results suggest that MSC‐derived CCN2 contributes to the promotion of proliferation, migration and invasion of TSCC cells and may be a possible therapy target in the future.

Review article: mesenchymal stromal cell therapy for inflammatory bowel diseases

BACKGROUND

Inflammatory bowel diseases (IBD) are chronic relapsing diseases in which pro-inflammatory immune cells and cytokines induce intestinal tissue damage and disability. Mesenchymal stromal cells (MSCs) exert powerful immunomodulatory effects and stimulate tissue repair.

AIM

To review the current data on mesenchymal stromal cell therapy in IBD.

METHOD

We searched PubMed and 'ClinicalTrials.gov' databases using the terms 'mesenchymal stromal cells', 'mesenchymal stem cell transplantation', 'inflammatory bowel diseases', 'Crohn disease' and 'colitis, ulcerative'. Additional publications were identified from individual article reference lists.

RESULTS

MSCs include inhibition of Th1/Th17 lymphocytes and recruitment of regulatory T lymphocytes, induction of antigen-presenting cells into a regulatory-like profile, and stimulation of epithelial cell differentiation and proliferation. More than 200 patients with refractory fistulas have been treated with local injections of MSCs, resulting in complete response in more than half, and in overall response in approximately two thirds of patients. In refractory luminal Crohn's disease, 49 cases of systemic MSC infusions have been reported, while trials with autologous MSCs resulted in mitigated responses, studies using allogeneic MSCs were promising, with around 60% of patients experiencing a response and around 40% achieving clinical remission.

CONCLUSIONS

Mesenchymal stromal cells might represent a promising therapy for IBD, especially for Crohn's disease. There remain many unsolved questions concerning the optimal origin and source of mesenchymal stromal cells, dosage and modalities of administration. Moreover, mesenchymal stromal cells still need to prove their effectiveness compared with conventional treatments in randomised controlled trials.

Treatment of chemically induced oral ulcer using adipose-derived mesenchymal stem cell sheet

BACKGROUND

This study investigated the effects of mesenchymal stem cell (MSC) sheet transplantation on healing of chemically induced oral ulceration in a rabbit animal model.

METHODS

Oral mucosal ulcers were induced by topical application of filter paper soaked with 70% acetic acid to the anterior gingiva and buccal mucosa of 12 New Zealand white rabbits. The animals were randomly assigned to two groups: with (treatment group, n = 6) or without (control group, n = 6) cell sheets applied to ulcers. Gross findings were sequentially evaluated, and histologic examination was performed on day 7.

RESULTS

Based on gross inspection, ulceration resolved before day 5 in the treatment group; however, in the control group, healing was incomplete on day 7. In the treatment group, the total area of the ulcer decreased significantly from day 2 to day 5 (P < 0.001) and from day 5 to day 7 (P = 0.020), whereas the area decreased significantly from day 5 to day 7 in the control group (P < 0.001). Histologic and immunofluorescence examination revealed full-thickness mucosa healing and complete basal cell coverage in the treatment group; in contrast, only partial healing was observed on day 7 in the control group.

CONCLUSIONS

Cell sheet technology using MSC can be an alternative treatment for oral ulcerations in that it can decrease healing time without invasive properties.

Mesenchymal Stromal Cells Can Regulate the Immune Response in the Tumor Microenvironment

The tumor microenvironment is a good target for therapy in solid tumors and hematological malignancies. Indeed, solid tumor cells' growth and expansion can influence neighboring cells' behavior, leading to a modulation of mesenchymal stromal cell (MSC) activities and remodeling of extracellular matrix components. This leads to an altered microenvironment, where reparative mechanisms, in the presence of sub-acute inflammation, are not able to reconstitute healthy tissue. Carcinoma cells can undergo epithelial mesenchymal transition (EMT), a key step to generate metastasis; these mesenchymal-like cells display the functional behavior of MSC. Furthermore, MSC can support the survival and growth of leukemic cells within bone marrow participating in the leukemic cell niche. Notably, MSC can inhibit the anti-tumor immune response through either carcinoma-associated fibroblasts or bone marrow stromal cells. Experimental data have indicated their relevance in regulating cytolytic effector lymphocytes of the innate and adaptive arms of the immune system. Herein, we will discuss some of the evidence in hematological malignancies and solid tumors. In particular, we will focus our attention on the means by which it is conceivable to inhibit MSC-mediated immune suppression and trigger anti-tumor innate immunity.

Current Perspective of Stem Cell Therapy in Neurodegenerative and Metabolic Diseases

Neurodegenerative diseases have been an unsolved riddle for quite a while; to date, there are no proper and effective curative treatments and only palliative and symptomatic treatments are available to treat these illnesses. The absence of therapeutic treatments for neurodegenerative ailments has huge economic hit and strain on the society. Pharmacotherapies and various surgical procedures like deep brain stimulation are being given to the patient, but they are only effective for the symptoms and not for the diseases. This paper reviews the recent studies and development of stem cell therapy for neurodegenerative disorders. Stem cell-based treatment is a promising new way to deal with neurodegenerative diseases. Stem cell transplantation can advance useful recuperation by delivering trophic elements that impel survival and recovery of host neurons in animal models and patients with neurodegenerative maladies. Several mechanisms, for example, substitution of lost cells, cell combination, release of neurotrophic factor, proliferation of endogenous stem cell, and transdifferentiation, may clarify positive remedial results. With the current advancements in the stem cell therapies, a new hope for the cure has come out since they have potential to be a cure for the same. This review compiles stem cell therapy recent conceptions in neurodegenerative and neurometabolic diseases and updates in this field. Graphical Absract ᅟ.

Mesenchymal Stem Cell Treatment of Inflammation-Induced Cancer

Cancer development is often associated with chronic inflammation. To date, research into inflammation-induced cancer has largely focused on chemokines, cytokines, and their downstream targets. These inflammatory mediators may promote tumor growth, invasion, metastasis, and facilitate angiogenesis. However, the exact mechanisms by which inflammation promotes neoplasia remain unclear. Inflammatory bowel disease (IBD) is characterized by recurrent, idiopathic intestinal inflammation, the complications of which are potentially fatal. IBD incidence in Australia is 24.2 per 100,000 and its peak onset is in people aged 15 to 24 years. Symptoms include abdominal pain, cramps, bloody stool, and persistent diarrhoea or constipation and so seriously compromise quality of life. However, due to its unknown etiology, current treatment strategies combat the symptoms rather than the disease and are limited by inefficacy, toxicity, and adverse side-effects. IBD is also associated with an increased risk of colorectal cancer, for which treatment options are similarly limited. In recent years, there has been much interest in the therapeutic potential of mesenchymal stem cells (MSCs). However, whether MSCs suppress or promote tumor development is still contentious within the literature. Many studies indicate that MSCs exert anti-tumor effects and suppress tumor growth, whereas other studies report pro-tumor effects. Studies using MSCs as treatment for IBD have shown promising results in both animal models and human trials. However, as MSC treatment is still novel, the long-term risks remain unknown. This review aims to summarize the current literature on MSC treatment of inflammation-induced cancer, with a focus on colorectal cancer resulting from IBD.

Recent discoveries concerning the tumor - mesenchymal stem cell interactions

Tumor microenvironment plays a crucial role in coordination with cancer cells in the establishment, growth and dissemination of the tumor. Among cells of the microenvironment, mesenchymal stem cells (MSCs) and their ability to evolve into cancer associated fibroblasts (CAFs) have recently generated a major interest in the field. Numerous studies have described the potential pro- or anti-tumorigenic action of MSCs. The goal of this review is to synthesize recent and emerging discoveries concerning the mechanisms by which MSCs can be attracted to tumor sites, how they can generate CAFs and by which way MSCs are able to modulate the growth, response to treatments, angiogenesis, invasion and metastasis of tumors. The understanding of the role of MSCs in tumor development has potential and clinical applications in terms of cancer management.

Engineered Mesenchymal Stem Cells as an Anti-Cancer Trojan Horse

Cell-based gene therapy holds a great promise for the treatment of human malignancy. Among different cells, mesenchymal stem cells (MSCs) are emerging as valuable anti-cancer agents that have the potential to be used to treat a number of different cancer types. They have inherent migratory properties, which allow them to serve as vehicles for delivering effective therapy to isolated tumors and metastases. MSCs have been engineered to express anti-proliferative, pro-apoptotic, and anti-angiogenic agents that specifically target different cancers. Another field of interest is to modify MSCs with the cytokines that activate pro-tumorigenic immunity or to use them as carriers for the traditional chemical compounds that possess the properties of anti-cancer drugs. Although there is still controversy about the exact function of MSCs in the tumor settings, the encouraging results from the preclinical studies of MSC-based gene therapy for a large number of tumors support the initiation of clinical trials.

Supportive therapies for prevention of hepatocellular carcinoma recurrence and preservation of liver function

Hepatocellular carcinoma (HCC) is one of the deadliest cancers in the world and is associated with a high risk of recurrence. The development of a wide range of new therapies is therefore essential. In this study, from the perspective of supportive therapy for the prevention of HCC recurrence and preservation of liver function in HCC patients, we surveyed a variety of different therapeutic agents. We show that branched chain amino acids (BCAA) supplementation and late evening snack with BCAA, strategies that address issues of protein-energy malnutrition, are important for liver cirrhotic patients with HCC. For chemoprevention of HCC recurrence, we show that viral control after radical treatment is important. We also reviewed the therapeutic potential of antiviral drugs, sorafenib, peretinoin, iron chelators. Sorafenib is a kinase inhibitor and a standard therapy in the treatment of advanced HCC. Peretinoin is a vitamin A-like molecule that targets the retinoid nuclear receptor to induce apoptosis and inhibit tumor growth in HCC cells. Iron chelators, such as deferoxamine and deferasirox, act to prevent cancer cell growth. These chelators may have potential as combination therapies in conjunction with peretinoin. Finally, we review the potential inhibitory effect of bone marrow cells on hepatocarcinogenesis.

IL-1β produced by aggressive breast cancer cells is one of the factors that dictate their interactions with mesenchymal stem cells through chemokine production

The aim of this work was to understand whether the nature of breast cancer cells could modify the nature of the dialog of mesenchymal stem cells (MSCs) with cancer cells. By treating MSCs with the conditioned medium of metastatic Estrogen-receptor (ER)-negative MDA-MB-231, or non-metastatic ER-positive MCF-7 breast cancer cells, we observed that a number of chemokines were produced at higher levels by MSCs treated with MDA-MB-231 conditioned medium (CM). MDA-MB-231 cells were able to induce NF-κB signaling in MSC cells. This was shown by the use of a NF-kB chemical inhibitor or an IκB dominant negative mutant, nuclear translocation of p65 and induction of NF-κB signature. Our results suggest that MDA-MB-231 cells exert their effects on MSCs through the secretion of IL-1β, that activates MSCs and induces the same chemokines as the MDA-MB-231CM. In addition, inhibition of IL-1β secretion in the MDA-MB-231 cells reduces the induced production of a panel of chemokines by MSCs, as well the motility of MDA-MB-231 cells. Our data suggest that aggressive breast cancer cells secrete IL-1β, which increases the production of chemokines by MSCs.

Harnessing mesenchymal stem cell homing as an anticancer therapy

INTRODUCTION

Mesenchymal stromal cells (MSCs) are non-hematopoietic progenitor cells that have been exploited as vehicles for cell-based cancer therapy. The general approach is based on the innate potential of adoptively applied MSC to undergo facilitated recruitment to malignant tissue. MSC from different tissue sources have been engineered using a variety of therapy genes that have shown efficacy in solid tumor models.

AREAS COVERED

In this review we will focus on the current developments of MSC-based gene therapy, in particular the diverse approaches that have been used for MSCs-targeted tumor therapy. We also discuss some outstanding issues and general prospects for their clinical application.

EXPERT OPINION

The use of modified mesenchymal stem cells as therapy vehicles for the treatment of solid tumors has progressed to the first generation of clinical trials, but the general field is still in its infancy. There are many questions that need to be addressed if this very complex therapy approach is widely applied in clinical settings. More must be understood about the mechanisms underlying tumor tropism and we need to identify the optimal source of the cells used. Outstanding issues also include the therapy transgenes used, and which tumor types represent viable targets for this therapy.

Inhibitory effect of genetically engineered mesenchymal stem cells with Apoptin on hepatoma cells in vitro and in vivo

Hepatocellular carcinoma (HCC) is an aggressive tumor and has become one of the most frequent causes of cancer death in the world. The rate of post-operative recurrence and metastasis are still high even though after surgical resection. It is a difficult problem with extraordinary importance for the clinical treatment. So stem cell therapy becomes one of the anti-tumor biotherapy methods which is exploring. Due to the feature of homing to tumor site and immunosuppressive, mesenchymal stem cells (MSCs) have the capacity of gene treatment to tumor as a vehicle. Apoptin derived from chicken anemia virus is one kind of protein with an inherent ability to lyse cancer cells while leaving normal cells unharmed. Adenovirus (Ad) vectors can be modified to deliver therapeutic genes with the advantages of low toxicity and high transfer capacity. Now it has not been reported that combining MSCs and Adenovirus with Apoptin are used in HCC treatment. This study intends to construct recombinant adenovirus which expresses Apoptin and then infects human bone marrow MSCs, and explore the migration of MSCs to the hepatoma cells and inhibitory effect of genetically engineered mesenchymal stem cells with Apoptin on hepatoma cells in vitro and in vivo. Our research successfully established the recombinant Ad which was constructed by Ad system, and obtained MSCs which could secrete Apoptin. We found that both the modified MSCs with Apoptin and their conditional medium significantly inhibited the proliferation of liver cancer cells HepG2, which provided a novel means and experimental basis for stem cell treatment for HCC. This study tries to search for a stem cell therapy for cancers, which will provide a new approach and experimental basis for the clinical treatment of cancer. At the same time, this research will also provide experimental basis for a novel in vivo drug delivery system through stem cells as vehicle, which will resolve immune rejection induced by repeated applications of drug directly delivered by Ad vectors and reduce the high cost of a large-scale production and purification of exogenous drugs.

Mesenchymal stem cells (MSCs) as skeletal therapeutics - an update

Mesenchymal stem cells hold the promise to treat not only several congenital and acquired bone degenerative diseases but also to repair and regenerate morbid bone tissues. Utilizing MSCs, several lines of evidences advocate promising clinical outcomes in skeletal diseases and skeletal tissue repair/regeneration. In this context, both, autologous and allogeneic cell transfer options have been utilized. Studies suggest that MSCs are transplanted either alone by mixing with autogenous plasma/serum or by loading onto repair/induction supportive resorb-able scaffolds. Thus, this review is aimed at highlighting a wide range of pertinent clinical therapeutic options of MSCs in the treatment of skeletal diseases and skeletal tissue regeneration. Additionally, in skeletal disease and regenerative sections, only the early and more recent preclinical evidences are discussed followed by all the pertinent clinical studies. Moreover, germane post transplant therapeutic mechanisms afforded by MSCs have also been conversed. Nonetheless, assertive use of MSCs in the clinic for skeletal disorders and repair is far from a mature therapeutic option, therefore, posed challenges and future directions are also discussed. Importantly, for uniformity at all instances, term MSCs is used throughout the review.

Multipotent mesenchymal stromal cells promote tumor growth in distinct colorectal cancer cells by a β1-integrin-dependent mechanism

Tumor-stroma interactions play an essential role in the biology of colorectal carcinoma (CRC). Multipotent mesenchymal stromal cells (MSC) may represent a pivotal part of the stroma in CRC, but little is known about the specific interaction of MSC with CRC cells derived from tumors with different mutational background. In previous studies we observed that MSC promote the xenograft growth of the CRC cell-line DLD1. In the present study, we aimed to analyze the mechanisms of MSC-promoted tumor growth using various in vitro and in vivo experimental models and CRC cells of different mutational status. MSC specifically interacted with distinct CRC cells and supported tumor seeding in xenografts. The MSC-CRC interaction facilitated three-dimensional spheroid formation in CRC cells with dysfunctional E-cadherin system. Stable knock-downs revealed that the MSC-facilitated spheroid formation depended on β1-integrin in CRC cells. Specifically in α-catenin-deficient CRC cells this β1-integrin-dependent interaction resulted in a MSC-mediated promotion of early tumor growth in vivo. Collagen I and other extracellular matrix compounds were pivotal for the functional MSC-CRC interaction. In conclusion, our data demonstrate a differential interaction of MSC with CRC cells of different mutational background. Our study is the first to show that MSC specifically compared to normal fibroblasts impact early xenograft growth of distinct α-catenin deficient CRC cells possibly through secretion of extracellular matrix. This mechanism could serve as a future target for therapy and metastasis prevention.

Bispecific antibody releasing-mesenchymal stromal cell machinery for retargeting T cells towards acute myeloid leukemia blasts

Bispecific antibodies (bsAbs) engaging T cells are emerging as a promising immunotherapeutic tool for the treatment of hematologic malignancies. Because their low molecular mass, bsAbs have short half-lives. To achieve clinical responses, they have to be infused into patients continously, for a long period of time. As a valid alternative we examined the use of mesenchymal stromal cells (MSCs) as autonomous cellular machines for the constant production of a recently described, fully humanized anti-CD33-anti-CD3 bsAb, which is capable of redirecting human T cells against CD33-expressing leukemic cells. The immortalized human MSC line SCP-1 was genetically modified into expressing bsAb at sufficient amounts to redirect T cells efficiently against CD33 presenting target cells, both in vitro and in an immunodeficient mouse model. Moreover, T cells of patients suffering from acute myeloid leukemia (AML) in blast crisis eliminated autologous leukemic cells in the presence of the bsAb secreting MSCs over time. The immune response against AML cells could be enhanced further by providing T cells an additional co-stimulus via the CD137-CD137 ligand axis through CD137L expression on MSCs. This study demonstrates that MSCs have the potential to be used as cellular production machines for bsAb-based tumor immunotherapy in the future.

Comparative study of various subpopulations of cytotoxic cells in blood and ascites from patients with ovarian carcinoma

AIM OF THE STUDY

A number of observations have indicated that the immune system plays a significant role in patients with epithelial ovarian cancer (EOC). In cases of EOC, the prognostic significance of tumour infiltrating lymphocytes has not been clearly explained yet. The aim is to determine the phenotype and activation molecules of cytotoxic T cell and NK cell subpopulations and to compare their representation in malignant ascites and peripheral blood in patients with ovarian cancer.

MATERIAL AND METHODS

Cytotoxic cells taken from blood samples of the cubital vein and malignant ascites were obtained from 53 patients with EOC. Their surface and activation characteristics were determined by means of a flow cytometer. Immunophenotype multiparametric analysis of peripheral blood lymphocytes (PBLs) and tumour infiltrating lymphocytes (TILs) was carried out.

RESULTS

CD3(+) T lymphocytes were the main population of TILs (75.9%) and PBLs (70.9%). The number of activating T cells was significantly higher in TILs: CD3(+)/69(+) 6.7% vs. 0.8% (p < 0.001). The representation of (CD3(-)/16(+)56(+)) NK cells in TILs was significantly higher: 11.0% vs. 5.6% (p = 0.041); likewise CD56(bright) and CD-56(bright) from CD56(+) cells were higher in TILs (both p < 0.001). The activation receptor NKG2D was present in 45.1% of TILs vs. 32.3% of PBLs (p = 0.034), but we did not find a significant difference in the numbers of CD56(+)/NKG2D(+) in TILs and PBLs.

CONCLUSIONS

These results prove that the characteristics and intensity of anti-tumour responses are different in compared compartments (ascites/PBLs). The knowledge of phenotype and functions of effector cells is the basic precondition for understanding the anti-tumour immune response.

Anti-metastatic effect and mechanisms of Wenshen Zhuanggu Formula in human breast cancer cells

ETHNOPHARMACOLOGICAL RELEVANCE

Wenshen Zhuanggu Formula (WSZG), a traditional Chinese medicine (TCM) empirical prescription, has been used to treat the patients with breast cancer bone metastasis as an adjuvant in clinical practice. To explore the anti-metastatic activity and potential mechanisms of WSZG-containing serum (WSZG-CS) on highly bone-metastatic human breast cancer MDA-MB-231BO cells.

MATERIALS AND METHODS

MDA-MB-231BO cells were cultured alone or co-cultured with bone marrow-derived mesenchymal stem cells (BMSCs). Invasion assays were carried out in Matrigel-coated Transwell chambers. CC chemokine 5 (CCL5) and interleukin (IL)-17B secretion levels were detected by ELISA. CCR5 and IL-17BR protein expression levels were determined by immunocytochemistry and Western blot analysis.

RESULTS

Compared with control serum, WSZG-CS significantly inhibited BMSC induced MDA-MB-231BO breast cancer cell invasion, reduced CCL5 and IL-17B levels in co-culture supernatants, and downregulated CCR5 and IL-17BR protein expression in breast cancer cells co-cultured with BMSCs.

CONCLUSIONS

WSZG-CS exerts an anti-metastatic activity against MDA-MB-231BO breast cancer cells, due to its ability to mitigate the interaction between BMSCs and breast cancer cells mediated via the CCL5/CCR5 and IL-17B/IL-17BR signaling pathways.

Stem cell-based treatments against stroke: observations from human proof-of-concept studies and considerations regarding clinical applicability

Ischemic stroke remains a heavy burden for industrialized countries. The only causal therapy is the recanalization of occluded vessels via thrombolysis, which due to a narrow time window still can be offered only to a minority of patients. Since the majority of patients continues to exhibit neurological deficits even following successful thrombolysis, restorative therapies are urgently needed that promote brain remodeling and repair once stroke injury has occurred. Due to their unique properties of action, stem cell-based strategies gained increasing interest during recent years. Using various stroke models in both rodents and primates, the transplantation of stem cells, namely of bone marrow derived mesenchymal stem cells (MSCs) or neural progenitor cells (NPCs), has been shown to promote neurological recovery most likely via indirect bystander actions. In view of promising observations, clinical proof-of-concept studies are currently under way, in which effects of stem and precursor cells are evaluated in human stroke patients. In this review we summarize already published studies, which due to the broad experience in other medical contexts mostly employed bone marrow-derived MSCs by means of intravenous transplantation. With the overall number of clinical trials limited in number, only a fraction of these studies used non-treated control groups, and only single studies were adequately blinded. Despite these limitations, first promising results justify the need for more elaborate clinical trials in order to make stem cell transplantation a success for stroke treatment in the future.

Arsenic trioxide and microRNA-204 display contrary effects on regulating adipogenic and osteogenic differentiation of mesenchymal stem cells in aplastic anemia

Our previous studies have demonstrated that arsenic trioxide (ATO) had the clinical efficacy in treating patients with aplastic anemia (AA). However, the mechanisms remain to be elucidated. The important components of the bone marrow hematopoietic microenvironment, bone marrow mesenchymal stem cells (BMSCs), are often altered in AA patients. In this study, it was found that AA BMSCs were prone to be induced into adipocytes rather than osteoblasts. ATO treatment can at least partially restore the differentiation imbalance of AA BMSCs. We further identified miR-204 as a key regulator in AA BMSC differentiation. Luciferase reporter assay showed that miR-204 could directly bind to the 3'-untranslated region of Runx2 mRNA, a key transcription factor regulating osteogenesis. Moreover, adipogenic differentiation was promoted and osteogenic differentiation was inhibited in miR-204 over-expressed cells, whereas osteogenesis was enhanced and adipocyte formation was inhibited in cells that lost miR-204 function, which suggested its endogenous function. Together we showed that ATO could inhibit adipogenic differentiation, but promote osteogenic differentiation in AA BMSCs, providing a possible explanation for ATO clinical efficacy in AA patients. MiR-204 plays a key role in regulating BMSCs differentiation, and down-regulating miR-204 expression might be a novel strategy to treat AA.

CD29 of human umbilical cord mesenchymal stem cells is required for expansion of CD34(+) cells

OBJECTIVES

Human umbilical cord mesenchymal stem cells (hUCMSCs) play a critical role in expanding haematopoietic stem cells (HSCs) by providing the essential microenvironment for haematopoiesis. In this study, we sought to investigate whether CD29 of hUCMSCs would play a key role in the ability of hUCMSCs to help expand HSCs in vivo and in vitro.

MATERIAL AND METHODS

To investigate whether CD29 of hUCMSCs would play a key role for the ability of hUCMSCs to expand HSCs, soluble anti-CD29 antibody was added to co-cultures of hUCMSCs and cord blood (CB) CD34(+) cells. It significantly blocked expansion of CB CD34(+) cells induced by hUCMSCs. Using CD29-deficient hUCMSCs models, long-term culture-initiating cell and non-obese diabetic/severe combined immunodeficient disease mouse repopulating cell assay, revealed that CB CD34(+) cells co-cultured with CD29-deficient hUCMSCs only retained the capacity of multipotent differentiation for 5 weeks at the most.

RESULTS

Soluble anti-CD29 antibody significantly blocked expansion of CB CD34(+) cells induced by hUCMSCs. CB CD34(+) cells co-cultured with CD29-deficient hUCMSCs only retained the capacity of multipotent differentiation for 5 weeks at the most.

CONCLUSIONS

CB CD34(+) cells co-cultured with CD29-deficient hUCMSCs gave rise to all major haematopoietic lineages, but failed to engraft long term.

Human bone marrow stromal cells lose immunosuppressive and anti-inflammatory properties upon oncogenic transformation

Because of their immunomodulatory properties, human bone marrow stromal cells (hBMSCs) represent promising stem cells for treatment of immune disorders. hBMSCs expansion precedes their clinical use, so the possibility that hBMSCs undergo spontaneous transformation upon long-term culture should be addressed. Whether hBMSCs retain immunosuppressive and anti-inflammatory properties upon oncogenic transformation remains unknown. Using sequentially mutated hBMSCs and spontaneously transformed hBMSCs, we report that, upon oncogenic transformation, hBMSCs lose immunosuppressive and anti-inflammatory properties in vitro and in vivo. Transcriptome profiling and functional assays reveal immune effectors underlying the loss of immunomodulation in transformed hBMSCs. They display a proinflammatory transcriptomic signature, with deregulation of immune and inflammatory modulators and regulators of the prostaglandin synthesis. Transformed hBMSCs lose their capacity to secrete the immunosuppressive prostacyclins prostaglandin E2 (PGE2) and PGI2 but produce proinflammatory thromboxanes. Together, the immunoregulatory profile adopted by hBMSCs largely depends on intrinsic genetic-molecular determinants triggered by genomic instability/oncogenic transformation.

•

Oncogenic hBMSCs display robustly impaired immune properties

•

Transformed hBMSCs display a proinflammatory transcriptomic signature

•

Transformed hBMSCs lose capacity to secrete immunosuppressive prostacyclins

•

Transformed hBMSCs gain the capacity to produce proinflammatory thromboxanes

Downregulated CXCL12 expression in mesenchymal stem cells associated with severe aplastic anemia in children

The mechanisms of idiopathic severe aplastic anemia (SAA) in children are not completely understood. Insufficiency of the bone marrow microenvironment, in which mesenchymal stem cells (MSCs) are an important element, can be a potential factor associated with hematopoietic impairment. In the current study, we studied whether aberrant gene expression could be found in MSCs from children with SAA. Using microarray analysis, two different patterns of global gene expression were detected in the SAA MSCs. Fourteen genes (POLE2, HGF, KIF20A, TK1, IL18R1, KITLG, FGF18, RRM2, TTK, CXCL12, DLG7, TOP2A, NUF2, and TYMS), which are related to DNA synthesis, cytokines, or growth factors, were significantly downregulated. Further, knockdown of gene expression was performed using the small hairpin RNA (shRNA)-containing lentivirus method. We found that knockdown of CXCL12, HGF, IL-18R1, FGF18, or RRM2 expression compelled MSCs from the controls to behave like those from the SAA children, with decreased survival and differentiation potential. Among them, inhibition of CXCL12 gene expression had the most profound effects on the behavior of MSCs. Further experiments regarding re-introduction of the CXCL12 gene could largely recover the survival and differentiation potential in MSCs with inhibition of CXCL12 expression. Our findings suggest that MSCs from children with SAA exhibit aberrant gene expression profiles and downregulation of CXCL12 gene may be associated with alterations in the bone marrow microenvironment.

Concise review: adult mesenchymal stromal cell therapy for inflammatory diseases: how well are we joining the dots?

Mesenchymal stromal (stem) cells (MSCs) continue to be a strong area of focus for academic- and industry-based researchers who share the goal of expanding their therapeutic use for diverse inflammatory and immune-mediated diseases. Recently, there has been an accelerated rate of scientific publication, clinical trial activity, and commercialisation in the field. This has included the reporting of exciting new developments in four areas that will be of key importance to future successful use of MSC-based therapies in large numbers of patients: (a) fundamental biology of the primary cells in bone marrow and other tissues that give rise to MSCs in culture. (b) Mechanisms by which MSCs modulate immune and inflammatory responses in vivo. (c) Insights into MSC kinetics, safety, and efficacy in relevant animal disease models. (d) Isolation, definition, and clinical trial-based testing of human MSCs by biomedical companies and academic medical centers. Despite this progress, it remains unclear whether MSCs will enter mainstream therapeutic practice as a frequently used alternative to pharmacotherapy or surgical/radiological procedures in the foreseeable future. In this review, we summarize some of the most significant new developments for each of the four areas that contribute to the process of translating MSC research to the clinical arena. In the context of this recent progress, we discuss key challenges and specific knowledge gaps which, if not addressed in a coordinated fashion, may hinder the creation of robust "translational pipelines" for consolidating the status of MSC-based therapies.

Regenerative therapy with mesenchymal stem cells at the site of malignant primary bone tumour resection: what are the risks of early or late local recurrence?

PURPOSE

There is concern that regenerative cell-based therapies at the site of malignant primary bone tumours could result in increased risk of local tumour recurrence. We therefore investigated the long-term risks for site-specific recurrences in patients who had received an autologous bone marrow derived mesenchymal stem cell suspension to improve healing at the host-to-allograft bone junction of the reconstruction after bone tumour resection.

METHODS

A total of 92 patients were treated from 1993 to 2003 with bone marrow-derived mesenchymal stem cells after bone tumour resection. Patients were monitored for cancer incidence from the date of first operation (1993) until death, or until 31 December 2013. The mean follow-up time was 15.4 years (range ten to 20 years). The average number of MSCs returned to the patient was 234,000 MSCs ± 215,000. The primary outcome was to evaluate the risk of tumorigenesis recurrence at the cell therapy treatment sites with radiographs and/or MRIs. The relative risk of cancer recurrence was expressed as the ratio of observed and expected number of cases according to three different control populations.

RESULTS

Thirteen recurrences were found at the treatment sites among the 92 patients. The expected number of recurrences based on incidence in the three cohort populations was between 15 and 20 for the same cancer, age and sex distribution. The standardized incidence ratio (equal to observed cancers divided by expected cancers) for the entire follow-up period and for all recurrences was between 0.65 and 0.86 (95 % CI 0.60-1.20).

CONCLUSION

This study found no increased cancer local recurrence risk in patients after application of autologous cell-based therapy using bone marrow-derived mesenchymal stem cells at the treatment site after an average follow-up period of 15.4 years, ranging from ten to 20 years.

β2-Microglobulin-mediated signaling as a target for cancer therapy

β2-microglobulin (β2-m) has become the focus of intense scrutiny since the discovery of its undesirable roles promoting osteomimicry and cancer progression. β2-m is a well-known housekeeping protein that forms complexes with the heavy chain of major histocompatibility complex class I molecules, which are heterodimeric cell surface proteins that present antigenic peptides to cytotoxic T cells. On recognition of foreign peptide antigens on cell surfaces, T cells actively bind and lyse antigen-presenting cancer cells. In addition to its roles in tumor immunity, β2-m has two different functions in cancer cells, either tumor promoting or tumor suppressing, in cancer cell context-dependent manner. Our studies have demonstrated that β2-m is involved extensively in the functional regulation of growth, survival, apoptosis, and even metastasis of cancer cells. We found that β2-m is a soluble growth factor and a pleiotropic signaling molecule which interacts with its receptor, hemochromatosis protein, to modulate epithelial-to-mesenchymal transition (EMT) through iron-responsive pathways. Specific antibodies against β2-m have remarkable tumoricidal activity in cancer, through β2-m action on iron flux, alterations of intracellular reactive oxygen species, DNA damage and repair enzyme activities, β-catenin activation and cadherin switching, and tumor responsiveness to hypoxia. These novel functions of β2-m and β2-m signaling may be common to several solid tumors including human lung, breast, renal, and prostate cancers. Our experimental results could lead to the development of a novel class of antibody-based pharmaceutical agents for cancer growth control. In this review, we briefly summarize the recent data regarding β2-m as a promising new cancer therapeutic target and discuss antagonizing this therapeutic target with antibody therapy for the treatment of localized and disseminated cancers.

The regulatory sciences for stem cell-based medicinal products

Over the past few years, several new achievements have been made from stem cell studies, many of which have moved up from preclinical stages to early, or from early to middle or late, stages thanks to relatively safe profile and preliminary evidence of effectiveness. Moreover, some stem cell-based products have been approved for marketing by different national regulatory authorities. However, many critical issues associated mainly with incomplete understanding of stem cell biology and the relevant risk factors, and lack of effective regulations still exist and need to be urgently addressed, especially in countries where establishment of appropriate regulatory system just commenced. More relevantly, the stem cell regulatory sciences need to be established or improved to more effectively evaluate quality, safety and efficacy of stem cell products, and for building up the appropriate regulatory framework. In this review, we summarize some new achievements in stem cell studies, especially the preclinical and clinical studies, the existing regulations, and the associated challenges, and we then propose some considerations for improving stem cell regulatory sciences with a goal of promoting the steadfast growth of the well-regulated stem cell therapies abreast of evolvement of stem cell sciences and technologies.

Mesenchymal stem cells, cancer challenges and new directions

Therapeutic use of multipotent mesenchymal stromal stem cells (MSC) is a promising venue for a large number of degenerative diseases and cancer. Their availability from many different adult tissues, ease of expansion in culture, the ability to avoid immune rejection and their homing ability, are some of the properties of MSCs that make them a great resource for therapy. However, the challenges and risks for cell-based therapies are multifaceted. The blessing of cell culture expansion also comes with a burden. During in vitro expansion, stem cells experience a long replicative history and therefore, become subjected to damage from intracellular and extracellular influences. As previously shown cells that are manipulated to obtain an expanded replicative potential are prone to spontaneous transformation in culture. These manipulations help bypass the naturally built-in controls of the cell that govern the delicate balance between cell proliferation, senescence and carcinogenesis. Because of this, there is a risk for patients receiving stem cells that are in vitro expanded. Whether these cells are genetically engineered or harbouring xenogenic compounds, they cannot truly be considered "safe" unless the cells are closely monitored. In the present communication, we will focus on the therapeutic potential of the human mesenchymal stem cells (hMSC) with special focus on their use in cancer therapy. We will consider different mechanisms, by which stem cells can maintain telomeres and thereby the cell's ability to be expanded in vitro, and also focus on a new therapeutic venue that utilises hMSCs as delivery vehicles in innovative new cancer treatments.

Stem cell bioprocess engineering towards cGMP production and clinical applications

Stem cells, including mesenchymal stem cells and pluripotent stem cells, are becoming an indispensable tool for various biomedical applications including drug discovery, disease modeling, and tissue engineering. Bioprocess engineering, targeting large scale production, provides a platform to generate a controlled microenvironment that could potentially recreate the stem cell niche to promote stem cell proliferation or lineage-specific differentiation. This survey aims at defining the characteristics of stem cell populations currently in use and the present-day limits in their applications for therapeutic purposes. Furthermore, a bioprocess engineering strategy based on bioreactors and 3-D cultures is discussed in order to achieve the improved stem cell yield, function, and safety required for production under current good manufacturing practices.

Enriched protein screening of human bone marrow mesenchymal stromal cell secretions reveals MFAP5 and PENK as novel IL-10 modulators

The secreted proteins from a cell constitute a natural biologic library that can offer significant insight into human health and disease. Discovering new secreted proteins from cells is bounded by the limitations of traditional separation and detection tools to physically fractionate and analyze samples. Here, we present a new method to systematically identify bioactive cell-secreted proteins that circumvent traditional proteomic methods by first enriching for protein candidates by differential gene expression profiling. The bone marrow stromal cell secretome was analyzed using enriched gene expression datasets in combination with potency assay testing. Four proteins expressed by stromal cells with previously unknown anti-inflammatory properties were identified, two of which provided a significant survival benefit to mice challenged with lethal endotoxic shock. Greater than 85% of secreted factors were recaptured that were otherwise undetected by proteomic methods, and remarkable hit rates of 18% in vitro and 9% in vivo were achieved.

Mesenchymal stromal cells induce epithelial-to-mesenchymal transition in human colorectal cancer cells through the expression of surface-bound TGF-β

Mesenchymal stem/stromal cells (MSC) are multipotent precursors endowed with the ability to home to primary and metastatic tumor sites, where they can integrate into the tumor-associated stroma. However, molecular mechanisms and outcome of their interaction with cancer cells have not been fully clarified. In this study, we investigated the effects mediated by bone marrow-derived MSC on human colorectal cancer (CRC) cells in vitro and in vivo. We found that MSC triggered epithelial-to-mesenchymal transition (EMT) in tumor cells in vitro, as indicated by upregulation of EMT-related genes, downregulation of E-cadherin and acquisition of mesenchymal morphology. These effects required cell-to-cell contact and were mediated by surface-bound TGF-β newly expressed on MSC upon coculture with tumor cells. In vivo tumor masses formed by MSC-conditioned CRC cells were larger and characterized by higher vessel density, decreased E-cadherin expression and increased expression of mesenchymal markers. Furthermore, MSC-conditioned tumor cells displayed increased invasiveness in vitro and enhanced capacity to invade peripheral tissues in vivo. Thus, by promoting EMT-related phenomena, MSC appear to favor the acquisition of an aggressive phenotype by CRC cells.

The challenge of pancreatic cancer therapy and novel treatment strategy using engineered mesenchymal stem cells

Mesenchymal stem cells (MSCs) have attracted significant attention in cancer research as a result of their accessibility, tumor-oriented homing capacity, and the feasibility of auto-transplantation. This review provides a comprehensive overview of current challenges in pancreatic cancer therapy, and we propose a novel strategy for using MSCs as means of delivering anticancer genes to the site of pancreas. We aim to provide a practical platform for the development of MSC-based therapy for pancreatic cancer.

Ex vivo microperfusion system of the adipose organ: a new approach to studying the mobilization of adipose cell populations

BACKGROUND/OBJECTIVES

Adipose tissue (AT) is a dynamic organ that expands and contracts rapidly. It is composed of adipocytes and of cell populations among which immune cells and mesenchymal progenitors known as adipose stromal cells (ASCs). The AT cell turnover has been extensively studied. Surprisingly it has only been viewed as the result of both cell proliferation/death and cell infiltration. Nevertheless, both immune cells and ASCs exhibit migration abilities; therefore their egress from AT in response to physiological/pathophysiological stimuli has to be considered. To do so, the aim of the present work was to develop a model allowing the study of cell release from the adipose organ.

SUBJECTS/METHODS

Mesenteric (Mes) ATs were isolated from 9-week-old C57BL/6 male mice and were catheterized via the superior mesenteric artery and were perfused with a saline solution. After an equilibration period, the mesenteric fat pad was perfused with CXCL12 (stromal-derived factor-1, SDF-1) or sphingosine 1-phosphate (S1P) to trigger cell mobilization and perfusates were collected every 30 min for subsequent flow cytometry analyses.

RESULTS

We report here that CXCL12 induces the specific release of ASCs from MesAT thus demonstrating that ASCs are specifically mobilized from fat depots by a CXCL12-dependent pathway. Moreover, we showed that leukocyte mobilization can be triggered via a S1P-dependent pathway.

CONCLUSIONS

We have developed a microperfusion model of an intact fat depot allowing the study of AT cell release in response to various molecules. The perfusion system described here demonstrates that ASCs and leukocytes can be pharmacologically mobilized from AT. Therefore, AT microperfusion might constitute an appropriate and reliable approach for evaluating the mobilization of different cell populations from AT in various physiological and pathophysiological contexts. Such a model might help in identifying factors and drugs controlling AT cell release, impacting the medical fields of regenerative medicine and of obesity or its associated comorbidities.

The role of mesenchymal stem cells in cancer development

The role of mesenchymal stem cells (MSCs) in cancer development is still controversial. MSCs may promote tumor progression through immune modulation, but other tumor suppressive effects of MSCs have also beendescribed. The discrepancy between these results may arise from issues related to different tissue sources, individual donor variability, and injection timing of MSCs. The expression of critical receptors such as Toll-like receptor is variable a teach time point of treatment, which may also determine the effects of MSCs on tumor progression. However, factors released from malignant cells, as well as surrounding tissues and the vasculature, are still regarded as a “black box. ” Thus, it is still difficult to clarify the specific role of MSCs in cancer development. Whether MSCs support or suppress tumor progression is currently unclear, but it is clear that systemically administered MSCs can be recruited and migrate toward tumors. These findings are important because they can be used as a basis for initiating studies to explore the incorporation of engineered MSCs as novel anti-tumor carriers, for the development of tumor-targeted therapies.

Characteristics of human adipose mesenchymal stem cells isolated from healthy and cancer affected people and their interactions with human breast cancer cell line MCF-7 in vitro

Adipose tissue is an attractive source of mesenchymal stem/stromal cells (MSCs) with potential applications in reconstructive plastic surgery and regenerative medicine. The aim of this study was to characterise human adipose tissue MSCs (ASCs) derived from healthy individuals and cancer patients and to compare their interactions with tumour cells. ASCs were isolated from adipose tissue of healthy donors, breast cancer-adjacent adipose tissue of breast cancer patients and tumour-adjacent adipose tissue of non-breast cancer patients. Their proliferation, differentiation, immunophenotype and gene expression were assessed and effects on the proliferation of human breast cancer cell line MCF-7 compared. ASCs from all sources exhibited similar morphology, proliferative and differentiation potential, showing the characteristic pattern of mesenchymal surface markers expression (CD90, CD105, CD44H, CD73) and the lack of HLA-DR and hematopoietic markers (CD11a, CD33, CD45, Glycophorin-CD235a), but uneven expression of CD34. ASCs also shared a common positive gene expression of HLA-DR, HLA-A, IL-6, TGF-β and HIF-1, but were negative for HLA-G, while the expression levels of Cox-2 and IDO-1 varied. All ASCs significantly stimulated the proliferation of MCF-7 tumour cells in direct mixed co-cultures and transwell system, although their conditioned media displayed antiproliferative activity. Data obtained showed that ASCs with similar characteristics are easily isolated from various donors and sites of origin, although ASCs could both suppress and favour tumour cells growth, emphasising the importance of cellular context within the microenvironment and pointing to the significance of safety studies to exclude any potential clinical risk of their application in regenerative medicine.