Mesenchymal stem cells as a double-edged sword in suppression or progression of solid tumor cells

Practical immunomodulatory landscape of glioblastoma multiforme (GBM) therapy

Glioblastoma multiforme (GBM) is the most common harmful high-grade brain tumor with high mortality and low survival rate. Importantly, besides routine diagnostic and therapeutic methods, modern and useful practical techniques are urgently needed for this serious malignancy. Correspondingly, the translational medicine focusing on genetic and epigenetic profiles of glioblastoma, as well as the immune framework and brain microenvironment, based on these challenging findings, indicates that key clinical interventions include immunotherapy, such as immunoassay, oncolytic viral therapy, and chimeric antigen receptor T (CAR T) cell therapy, which are of great importance in both diagnosis and therapy. Relatively, vaccine therapy reflects the untapped confidence to enhance GBM outcomes. Ongoing advances in immunotherapy, which utilizes different methods to regenerate or modify the resistant body for cancer therapy, have revealed serious results with many different problems and difficulties for patients. Safe checkpoint inhibitors, adoptive cellular treatment, cellular and peptide antibodies, and other innovations give researchers an endless cluster of instruments to plan profoundly in personalized medicine and the potential for combination techniques. In this way, antibodies that block immune checkpoints, particularly those that target the program death 1 (PD-1)/PD-1 (PD-L1) ligand pathway, have improved prognosis in a wide range of diseases. However, its use in combination with chemotherapy, radiation therapy, or monotherapy is ineffective in treating GBM. The purpose of this review is to provide an up-to-date overview of the translational elements concentrating on the immunotherapeutic field of GBM alongside describing the molecular mechanism involved in GBM and related signaling pathways, presenting both historical perspectives and future directions underlying basic and clinical practice.

3D modular bioceramic scaffolds for the investigation of the interaction between osteosarcoma cells and MSCs

Recent advances in bone tissue engineering have shown promise for bone repair post osteosarcoma excision. However, conflicting research on mesenchymal stem cells (MSCs) has raised concerns about their potential to either promote or inhibit tumor cell proliferation. It is necessary to thoroughly understand the interactions between MSCs and tumor cells. Most previous studies only focused on the interactions between cells within the tumor tissues. It has been challenging to develop an in vitro model of osteosarcoma excision sites replicating the complexity of the bone microenvironment and cell distribution. In this work, we designed and fabricated modular bioceramic scaffolds to assemble into a co-culture model. Because of the bone-like composition and mechanical property, tricalcium phosphate bioceramic could mimic the bone microenvironment and recapitulate the cell-extracellular matrix interaction. Moreover, the properties for easy assembly enabled the modular units to mimic the spatial distribution of cells in the osteosarcoma excision site. Under this co-culture model, MSCs showed a noticeable tumor-stimulating effect with a potential risk of tumor recurrence. In addition, tumor cells also could inhibit the osteogenic ability of MSCs. To undermine the stimulating effects of MSCs on tumor cells, we present the methods of pre-differentiated MSCs, which had lower expression of IL-8 and higher expression of osteogenic proteins. Both in vitro and in vivo studies confirm that pre-differentiated MSCs could maintain high osteogenic capacity without promoting tumor growth, offering a promising approach for MSCs' application in bone regeneration. Overall, 3D modular scaffolds provide a valuable tool for constructing hard tissue in vitro models. STATEMENT OF SIGNIFICANCE: Bone tissue engineering using mesenchymal stem cells (MSCs) and biomaterials has shown promise for bone repair post osteosarcoma excision. However, conflicting researches on MSCs have raised concerns about their potential to either promote or inhibit tumor cell proliferation. It remains challenges to develop in vitro models to investigate cell interactions, especially of osteosarcoma with high hardness and special composition of bone tissue. In this work, modular bioceramic scaffolds were fabricated and assembled to co-culture models. The interactions between MSCs and MG-63 were manifested as tumor-stimulating and osteogenesis-inhibiting, which means potential risk of tumor recurrence. To undermine the stimulating effect, pre-differentiation method was proposed to maintain high osteogenic capacity without tumor-stimulating, offering a promising approach for MSCs' application in bone regeneration.

Secretome from iPSC-derived MSCs exerts proangiogenic and immunosuppressive effects to alleviate radiation-induced vascular endothelial cell damage

BACKGROUND

Radiation therapy is the standard of care for central nervous system tumours. Despite the success of radiation therapy in reducing tumour mass, irradiation (IR)-induced vasculopathies and neuroinflammation contribute to late-delayed complications, neurodegeneration, and premature ageing in long-term cancer survivors. Mesenchymal stromal cells (MSCs) are adult stem cells that facilitate tissue integrity, homeostasis, and repair. Here, we investigated the potential of the iPSC-derived MSC (iMSC) secretome in immunomodulation and vasculature repair in response to radiation injury utilizing human cell lines.

METHODS

We generated iPSC-derived iMSC lines and evaluated the potential of their conditioned media (iMSC CM) to treat IR-induced injuries in human monocytes (THP1) and brain vascular endothelial cells (hCMEC/D3). We further assessed factors in the iMSC secretome, their modulation, and the molecular pathways they elicit.

RESULTS

Increasing doses of IR disturbed endothelial tube and spheroid formation in hCMEC/D3. When IR-injured hCMEC/D3 (IR ≤ 5 Gy) were treated with iMSC CM, endothelial cell viability, adherence, spheroid compactness, and proangiogenic sprout formation were significantly ameliorated, and IR-induced ROS levels were reduced. iMSC CM augmented tube formation in cocultures of hCMEC/D3 and iMSCs. Consistently, iMSC CM facilitated angiogenesis in a zebrafish model in vivo. Furthermore, iMSC CM suppressed IR-induced NFκB activation, TNF-α release, and ROS production in THP1 cells. Additionally, iMSC CM diminished NF-kB activation in THP1 cells cocultured with irradiated hCMEC/D3, iMSCs, or HMC3 microglial lines. The cytokine array revealed that iMSC CM contains the proangiogenic and immunosuppressive factors MCP1/CCL2, IL6, IL8/CXCL8, ANG (Angiogenin), GROα/CXCL1, and RANTES/CCL5. Common promoter regulatory elements were enriched in TF-binding motifs such as androgen receptor (ANDR) and GATA2. hCMEC/D3 phosphokinome profiling revealed increased expression of pro-survival factors, the PI3K/AKT/mTOR modulator PRAS40 and β-catenin in response to CM. The transcriptome analysis revealed increased expression of GATA2 in iMSCs and the enrichment of pathways involved in RNA metabolism, translation, mitochondrial respiration, DNA damage repair, and neurodevelopment.

CONCLUSIONS

The iMSC secretome is a comodulated composite of proangiogenic and immunosuppressive factors that has the potential to alleviate radiation-induced vascular endothelial cell damage and immune activation.

Role of Mesenchymal Stem/Stromal Cells in Head and Neck Cancer-Regulatory Mechanisms of Tumorigenic and Immune Activity, Chemotherapy Resistance, and Therapeutic Benefits of Stromal Cell-Based Pharmacological Strategies

Head and neck cancer (HNC) entails a heterogenous neoplastic disease that arises from the mucosal epithelium of the upper respiratory system and the gastrointestinal tract. It is characterized by high morbidity and mortality, being the eighth most common cancer worldwide. It is believed that the mesenchymal/stem stromal cells (MSCs) present in the tumour milieu play a key role in the modulation of tumour initiation, development and patient outcomes; they also influence the resistance to cisplatin-based chemotherapy, the gold standard for advanced HNC. MSCs are multipotent, heterogeneous and mobile cells. Although no MSC-specific markers exist, they can be recognized based on several others, such as CD73, CD90 and CD105, while lacking the presence of CD45, CD34, CD14 or CD11b, CD79α, or CD19 and HLA-DR antigens; they share phenotypic similarity with stromal cells and their capacity to differentiate into other cell types. In the tumour niche, MSC populations are characterized by cell quiescence, self-renewal capacity, low reactive oxygen species production and the acquisition of epithelial-to-mesenchymal transition properties. They may play a key role in the process of acquiring drug resistance and thus in treatment failure. The present narrative review examines the links between MSCs and HNC, as well as the different mechanisms involved in the development of resistance to current chemo-radiotherapies in HNC. It also examines the possibilities of pharmacological targeting of stemness-related chemoresistance in HNSCC. It describes promising new strategies to optimize chemoradiotherapy, with the potential to personalize patient treatment approaches, and highlights future therapeutic perspectives in HNC.

Revisiting the role of mesenchymal stromal cells in cancer initiation, metastasis and immunosuppression

Immune checkpoint blockade (ICB) necessitates a thorough understanding of intricate cellular interactions within the tumor microenvironment (TME). Mesenchymal stromal cells (MSCs) play a pivotal role in cancer generation, progression, and immunosuppressive tumor microenvironment. Within the TME, MSCs encompass both resident and circulating counterparts that dynamically communicate and actively participate in TME immunosurveillance and response to ICB. This review aims to reevaluate various facets of MSCs, including their potential self-transformation to function as cancer-initiating cells and contributions to the creation of a conducive environment for tumor proliferation and metastasis. Additionally, we explore the immune regulatory functions of tumor-associated MSCs (TA-MSCs) and MSC-derived extracellular vesicles (MSC-EVs) with analysis of potential connections between circulating and tissue-resident MSCs. A comprehensive understanding of the dynamics of MSC-immune cell communication and the heterogeneous cargo of tumor-educated versus naïve MSCs may unveil a new MSC-mediated immunosuppressive pathway that can be targeted to enhance cancer control by ICB.

Mesenchymal stem cells-derived IL-6 promotes invasion and metastasis of oral squamous cell carcinoma via JAK-STAT3 signalling

OBJECTIVES

Oral squamous cell carcinoma (OSCC) is often diagnosed with cervical lymph node metastasis. Mesenchymal stem cells (MSCs) and interleukin-6 (IL-6) signalling are considered to play important roles in promoting tumour malignancy. The detailed biological interaction of MSCs and IL-6 and the subsequent effect on OSCC metastasis remain largely unclear. This study aimed to determine the effects and molecular mechanism of MSCs-derived IL-6 on tumour invasion and metastasis.

SUBJECTS AND METHODS

The effects of MSC-derived IL-6 and tocilizumab on the proliferation, mobility, and epithelial-mesenchymal transition (EMT) of OSCC cells and potential pathways were detected in vitro. In addition, a murine xenograft model was generated to verify the biological mechanism in vivo.

RESULTS

The results showed that the expression of MSCs and EMT-related signals was increased in poorly differentiated OSCC tissues. MSCs released a higher level of IL-6 and promoted the proliferation, invasion, and metastasis of OSCC cells and solid neoplasms, which were activated by the downstream molecules JAK and STAT3.

CONCLUSIONS

The results indicated that MSCs-derived IL-6-promoted tumour invasion and metastasis via JAK-STAT3 signalling. Blockade of this pathway by tocilizumab may be a potential treatment to improve the prognosis and survival rate of patients with OSCC.

Poly I:C-priming of adipose-derived mesenchymal stromal cells promotes a pro-tumorigenic phenotype in an immunocompetent mouse model of prostate cancer

Introduction: Mesenchymal stromal cells (MSC) are envisioned as a potential cellular vehicle for targeted cancer therapies due to their tumor tropism and immune permissiveness. An obstacle in their use is the duality in their interactions within tumors, rendering them pro-tumorigenic or anti-tumorigenic, in a context dependent manner. MSC preconditioning, or priming, has been proposed as a strategy for directing the effector properties of MSC at tumor sites. Methods: We primed human MSC derived from adipose tissues (ASC), a clinically advantageous MSC source, utilizing toll-like receptor agonists. Subsequently, we explored the consequences in tumor progression and transcriptome upon the interaction of tumor cells with primed or unprimed ASC in an in vivo model of prostate cancer, the second most common cancer and second leading cause of cancer related death in men in the USA. Results and discussion: In the studied model, poly I:C-primed ASC were found to significantly accelerate tumor growth progression. And while unprimed and LPS-primed ASC did not exert a significant effect on tumor growth at the macroscopic level, gene expression analyses suggested that all treatments promoted distinct modulatory effects in the tumor microenvironment, including altered modulation of angiogenesis, and immune response processes. However, the effects resulting from the collective interaction across these processes must be sufficiently skewed in a pro-tumorigenic or anti-tumorigenic direction for evidence of tumor progression modulation to be detectable at the macroscopic level. Our study highlights potential MSC-tumor microenvironment interactions that may be leveraged and should be considered in the development of cancer therapeutics utilizing MSC.

Oncolytic viruses as emerging therapy against cancers including Oncovirus-induced cancers

There are several human viruses with known potential for causing cancers including, Hepatitis B virus, Hepatitis C virus, Epstein-Barr virus, Kaposi's sarcoma herpesvirus, Human T-cell lymphotropic virus, Human papillomavirus, and Merkel cell polyomavirus. Cancer is the second leading cause of death that affects humans worldwide, especially in developing countries. Surgery, chemotherapy, and radiotherapy can cure about 60% of humans with cancer but recurrent and metastatic diseases remain a major reason for death. In recent years, understanding the molecular characteristics of cancer cells has led to the improvement of therapeutic strategies using novel emerging therapies. Oncolytic viruses with the potential of lysing cancer cells defined the field of oncolytic virology, hence becoming a biotechnology tool rather than just a cause of disease. This study mainly focused on targeting cell proliferation and death pathways in human tumor-inducing viruses by developing innovative therapies for cancer patients based on the natural oncolytic properties of reovirus. To kill tumor cells efficiently and reduce the chance of recurrence both the direct ability of reovirus infection to lyse the tumor cells and the stimulation of a potent host immune response are applied. Hence, bioengineered stem cells can be used as smart carriers to improve the efficacy of oncolytic reovirus and safety profiles.

Effective-mononuclear cell (E-MNC) therapy alleviates salivary gland damage by suppressing lymphocyte infiltration in Sjögren-like disease

Introduction: Sjögren syndrome (SS) is an autoimmune disease characterized by salivary gland (SG) destruction leading to loss of secretory function. A hallmark of the disease is the presence of focal lymphocyte infiltration in SGs, which is predominantly composed of T cells. Currently, there are no effective therapies for SS. Recently, we demonstrated that a newly developed therapy using effective-mononuclear cells (E-MNCs) improved the function of radiation-injured SGs due to anti-inflammatory and regenerative effects. In this study, we investigated whether E-MNCs could ameliorate disease development in non-obese diabetic (NOD) mice as a model for primary SS. Methods: E-MNCs were obtained from peripheral blood mononuclear cells (PBMNCs) cultured for 7 days in serum-free medium supplemented with five specific recombinant proteins (5G culture). The anti-inflammatory characteristics of E-MNCs were then analyzed using a co-culture system with CD3/CD28-stimulated PBMNCs. To evaluate the therapeutic efficacy of E-MNCs against SS onset, E-MNCs were transplanted into SGs of NOD mice. Subsequently, saliva secretion, histological, and gene expression analyses of harvested SG were performed to investigate if E-MNCs therapy delays disease development. Results: First, we characterized that both human and mouse E-MNCs exhibited induction of CD11b/CD206-positive cells (M2 macrophages) and that human E-MNCs could inhibit inflammatory gene expressions in CD3/CD28- stimulated PBMNCs. Further analyses revealed that Msr1-and galectin3-positive macrophages (immunomodulatory M2c phenotype) were specifically induced in E-MNCs of both NOD and MHC class I-matched mice. Transplanted E-MNCs induced M2 macrophages and reduced the expression of T cell-derived chemokine-related and inflammatory genes in SG tissue of NOD mice at SS-onset. Then, E-MNCs suppressed the infiltration of CD4-positive T cells and facilitated the maintenance of saliva secretion for up to 12 weeks after E-MNC administration. Discussion: Thus, the immunomodulatory actions of E-MNCs could be part of a therapeutic strategy targeting the early stage of primary SS.

Role of stem cells in regenerative treatment of dry eye disease caused by lacrimal gland dysfunction

An ageing population and increased screen use in younger people have contributed to a rise in incidence of dry eye disease (DED). Quality of life can be significantly affected by DED, with patients experiencing eye dryness, burning, pain and sensitivity to light. If left untreated, DED may progress to cause lasting damage to the delicate cell layers of the ocular surface. The aqueous-deficient form of DED is characterized by decreased tear volume. This can occur through underlying disease or damage to the lacrimal gland (LG), which results in increased inflammation at the ocular surface and decreased tear secretion. Regenerative therapy for treatment of aqueous-deficient DED would ideally restore LG function without causing adverse side effects and be feasible in terms of cost, production and practical application in the clinic. In this review, we evaluate research directed at the development of clinical procedures for regeneration of the LG using various stem cell types and their products. We also discuss work identifying potential therapeutic targets that may alter pathways to effect healing and ameliorate development of DED. Finally, we discuss shortcomings and recommend future avenues for research. These include determination of the best tissue of origin for mesenchymal cells and transference of knowledge gleaned from animal studies to clinical investigations.

Human Mesenchymal Stromal Cells Do Not Cause Radioprotection of Head-and-Neck Squamous Cell Carcinoma

Radiotherapy of head-and-neck squamous cell carcinoma (HNSCC) can cause considerable normal tissue injuries, and mesenchymal stromal cells (MSCs) have been shown to aid regeneration of irradiation-damaged normal tissues. However, utilization of MSC-based treatments for HNSCC patients undergoing radiotherapy is hampered by concerns regarding potential radioprotective effects. We therefore investigated the influence of MSCs on the radiosensitivity of HNSCCs. Several human papillomavirus (HPV)-negative and HPV-positive HNSCCs were co-cultured with human bone marrow-derived MSCs using two-dimensional and three-dimensional assays. Clonogenic survival, proliferation, and viability of HNSCCs after radiotherapy were assessed depending on MSC co-culture. Flow cytometry analyses were conducted to examine the influence of MSCs on irradiation-induced cell cycle distribution and apoptosis induction in HNSCCs. Immunofluorescence stainings of γH2AX were conducted to determine the levels of residual irradiation-induced DNA double-strand breaks. Levels of connective tissue growth factor (CTGF), a multifunctional pro-tumorigenic cytokine, were analyzed using enzyme-linked immunosorbent assays. Neither direct MSC co-culture nor MSC-conditioned medium exerted radioprotective effects on HNSCCs as determined by clonogenic survival, proliferation, and viability assays. Consistently, three-dimensional microwell arrays revealed no radioprotective effects of MSCs. Irradiation resulted in a G2/M arrest of HNSCCs at 96 h independently of MSC co-culture. HNSCCs’ apoptosis rates were increased by irradiation irrespective of MSCs. Numbers of residual γH2AX foci after irradiation with 2 or 8 Gy were comparable between mono- and co-cultures. MSC mono-cultures and HNSCC-MSC co-cultures exhibited comparable CTGF levels. We did not detect radioprotective effects of human MSCs on HNSCCs. Our results suggest that the usage of MSC-based therapies for radiotherapy-related toxicities in HNSCC patients may be safe in the context of absent radioprotection.

Diagnostic and Therapeutic Potential of Extracellular Vesicles

Extracellular vesicles (EVs) are naturally phospholipid enclosed nanovesicles released by many cells in the body. They are stable in circulation, have low immunogenicity, and act as carriers for functionally active biological molecules. They interact with target organs and bind to the receptors. Their target specificity is important to use EVs as noninvasive diagnostic and prognostic tools. EVs play a vital role in normal physiology and cellular communication. They are known to protect their cargo from degradation, which makes them important drug carriers for targeted drug delivery. Using EVs with markers and tracking their path in systemic circulation can be revolutionary in using them as diagnostic tools. We will discuss the scope of this in this paper. Although there are limitations in EVs isolation and storage, their high biocompatibility will fuel more innovations to overcome these challenges.

Prospects for Manipulation of Mesenchymal Stem Cells in Tumor Therapy: Anti-Angiogenesis Property on the Spotlight

The interactions between the tumor microenvironment and the tumor cells confers a condition that accelerate or decelerate the development of tumor. Of these cells, mesenchymal stem cells (MSCs) have the potential to modulate the tumor cells. MSCs have been established with double functions, whereby contribute to a tumorigenic or anti-tumor setting. Clinical studies have indicated the potential of MSCs to be used as tool in treating the human cancer cells. One of the advantageous features of MSCs that make them as a well-suited tool for cancer therapy is the natural tumor-trophic migration potential. A key specification of the tumor development has been stablished to be angiogenesis. As a result, manipulation of angiogenesis has become an attractive approach for cancer therapy. This review article will seek to clarify the anti-angiogenesis strategy in modulating the MSCs to treat the tumor cells.

The Phosphonate Derivative of C60 Fullerene Induces Differentiation towards the Myogenic Lineage in Human Adipose-Derived Mesenchymal Stem Cells

Inductors of myogenic stem cell differentiation attract attention, as they can be used to treat myodystrophies and post-traumatic injuries. Functionalization of fullerenes makes it possible to obtain water-soluble derivatives with targeted biochemical activity. This study examined the effects of the phosphonate C₆₀ fullerene derivatives on the expression of myogenic transcription factors and myogenic differentiation of human mesenchymal stem cells (MSCs). Uptake of the phosphonate C₆₀ fullerene derivatives in human MSCs, intracellular ROS visualization, superoxide scavenging potential, and the expression of myogenic, adipogenic, and osteogenic differentiation genes were studied. The prolonged MSC incubation (within 7–14 days) with the C₆₀ pentaphoshonate potassium salt promoted their differentiation towards the myogenic lineage. The transcription factors and gene expressions determining myogenic differentiation (MYOD1, MYOG, MYF5, and MRF4) increased, while the expression of osteogenic differentiation factors (BMP2, BMP4, RUNX2, SPP1, and OCN) and adipogenic differentiation factors (CEBPB, LPL, and AP2 (FABP4)) was reduced or did not change. The stimulation of autophagy may be one of the factors contributing to the increased expression of myogenic differentiation genes in MSCs. Autophagy may be caused by intracellular alkalosis and/or short-term intracellular oxidative stress.

Mesenchymal Stem Cell-Derived Exosomes as an Emerging Paradigm for Regenerative Therapy and Nano-Medicine: A Comprehensive Review

Mesenchymal Stem Cells are potent therapeutic candidates in the field of regenerative medicine, owing to their immunomodulatory and differentiation potential. However, several complications come with their translational application like viability, duration, and degree of expansion, long-term storage, and high maintenance cost. Therefore, drawbacks of cell-based therapy can be overcome by a novel therapeutic modality emerging in translational research and application, i.e., exosomes. These small vesicles derived from mesenchymal stem cells are emerging as new avenues in the field of nano-medicine. These nano-vesicles have caught the attention of researchers with their potency as regenerative medicine both in nanotherapeutics and drug delivery systems. In this review, we discuss the current knowledge in the biology and handling of exosomes, with their limitations and future applications. Additionally, we highlight current perspectives that primarily focus on their effect on various diseases and their potential as a drug delivery vehicle.

Bioprintable Lung Extracellular Matrix Hydrogel Scaffolds for 3D Culture of Mesenchymal Stromal Cells

Mesenchymal stromal cell (MSC)-based cell therapy in acute respiratory diseases is based on MSC secretion of paracrine factors. Several strategies have proposed to improve this are being explored including pre-conditioning the MSCs prior to administration. We here propose a strategy for improving the therapeutic efficacy of MSCs based on cell preconditioning by growing them in native extracellular matrix (ECM) derived from the lung. To this end, a bioink with tunable stiffness based on decellularized porcine lung ECM hydrogels was developed and characterized. The bioink was suitable for 3D culturing of lung-resident MSCs without the need for additional chemical or physical crosslinking. MSCs showed good viability, and contraction assays showed the existence of cell–matrix interactions in the bioprinted scaffolds. Adhesion capacity and length of the focal adhesions formed were increased for the cells cultured within the lung hydrogel scaffolds. Also, there was more than a 20-fold increase of the expression of the CXCR4 receptor in the 3D-cultured cells compared to the cells cultured in plastic. Secretion of cytokines when cultured in an in vitro model of lung injury showed a decreased secretion of pro-inflammatory mediators for the cells cultured in the 3D scaffolds. Moreover, the morphology of the harvested cells was markedly different with respect to conventionally (2D) cultured MSCs. In conclusion, the developed bioink can be used to bioprint structures aimed to improve preconditioning MSCs for therapeutic purposes.

Importance of the origin of mesenchymal (stem) stromal cells in cancer biology: "alliance" or "war" in intercellular signals

Mesenchymal stem cells (MSCs) play a central role in the intercellular signaling within the tumor microenvironment (TME), exchanging signals with cancer cells and tumor stromal cells, such as cancer-associated fibroblasts and inflammatory mononuclear cells. Research attributes both pro-tumor and anti-tumor actions to MSCs; however, evidence indicates that MSCs specific effect on the tumor depends on the source of the MSCs and the type of tumor. There are consistent data proving that MSCs from reproductive tissues, such as the uterus, umbilical cord or placenta, have potent anti-tumor effects and tropism towards tumor tissues. More interestingly, products derived from MSCs, such as secretome or extracellular vesicles, seem to reproduce the effects of their parental cells, showing a potential advantage for clinical treatments by avoiding the drawbacks associated with cell therapy. Given these perspectives, it appears necessary new research to optimize the production, safety and antitumor potency of the products derived from the MSCs suitable for oncological therapies.

MSCs loaded with oncolytic reovirus: migration and in vivo virus delivery potential for evaluating anti-cancer effect in tumor-bearing C57BL/6 mice

Background and aims

Several oncolytic viruses applications have been approved in the clinic or in different phases of clinical trials. However, these methods have some rudimentary problems. Therefore, to enhance the delivery and quality of treatment, considering the advantage of cell carrier-based methods such as Mesenchymal Stem Cells (MSC) have been proposed. This study was designed to evaluate the performance and quality of cancer treatment based on MSCs loaded by oncolytic reovirus in the cancerous C57BL/6 mouse model. Also, we evaluated MSCs migration potency in vitro and in vivo following the oncolytic reovirus infection.

Methods

C57BL/6 mice were inoculated with TC-1 cell lines and tumors were established in the right flank. Mice were systemically treated with reovirus, MSCs-loaded with reovirus, MSCs, and PBS as a control in separated groups. Effects of infected AD-MSCs with reovirus on tumor growth and penetration in the tumor site were monitored. All groups of mice were monitored for two months in order to therapeutic and anticancer potential. After treatments, tumor size alteration and apoptosis rate, as well as cytokine release pattern was assessed.

Results

The results of the current study indicated that the effect of reovirus infection on AD-MSCs is not devastating the migration capacity especially in MOI 1 and 5 while intact cells remain. On the other hand, MSCs play an efficient role as a carrier to deliver oncolytic virus into the tumor site in comparison with systemic administration of reovirus alone. Apoptosis intensity relies on viral titration and passing time. Followed by systemic administration, treatment with oncolytic reovirus-infected AD-MSCs and MSCs alone had shown significant inhibition in tumor growth. Also, treatment by reovirus causes an increase in IFN-γ secretion.

Conclusion

The results of in vitro and in vivo study confirmed the tumor-homing properties of infected AD-MSCs and the significant antitumor activity of this platform. Hence, our results showed that the cell carrier strategy using oncolytic reovirus-loaded AD-MSCs enhanced virus delivery, infiltration, and antitumor activity can be effectively applied in most cancers.

No influence on tumor growth by intramuscular injection of adipose-derived regenerative cells: safety evaluation of therapeutic angiogenesis with cell therapy

Therapeutic angiogenesis with autologous stem/progenitor cells is a promising novel strategy for treatment of severe ischemic diseases. Human clinical trials utilizing autologous adipose-derived regenerative cells (ADRCs) have not reported treatment-related critical adverse effects thus far. However, there is still a large knowledge gap regarding whether treatment of ischemic diseases with angiogenic therapy using ADRCs would promote unfavorable angiogenesis associated with tumors in vivo. Herein, we addressed this clinical question using a mouse hindlimb ischemia (HLI) and simultaneous remote tumor implantation model. C57BL/6J background wild-type mice were injected with murine B16F10 melanoma cells on their back, 1 day before ischemic surgery. These mice were subjected to surgical unilateral hindlimb ischemia, followed by ADRC implantation or PBS injection into the hindlimb ischemic muscles on the next day. Intramuscular implantation of ADRCs enhanced tissue capillary density and blood flow examined by a laser Doppler blood perfusion analysis in hind limb. However, this therapeutic regimen for ischemic limb using ADRCs did not affect remote melanoma growth nor the density of its feeder artery, angiogenesis, and lymphatic vessels compared with the PBS group. In addition, no distant metastases were detected in any of the mice regardless of the group. In conclusion, local implantation of ADRCs promotes angiogenesis in response to tissue ischemia in the hindlimb without promoting remote tumor growth and related angio/lymphangiogenesis. Therapeutic angiogenesis to the ischemic hindlimb using ADRCs seems to be safe regarding remote tumor growth.NEW & NOTEWORTHY In this study, we demonstrated that local injection of ADRCs can promote angiogenesis in response to tissue ischemia without promoting remote tumor growth in a mouse model. Our findings indicate that therapeutic angiogenesis to the ischemic hindlimb using ADRCs seems to be safe regarding remote tumor growth.

Bone marrow mesenchymal stem cells interact with head and neck squamous cell carcinoma cells to promote cancer progression and drug resistance

Head and neck cancers are often diagnosed at later stages with poor outcomes. Mesenchymal stem cells (MSC) are recruited to primary tumor sites where they can have pro- and antitumorigenic influence. In trying to better understand the dynamics between MSC and cancer cells, we found that head and neck cancer-MSC exposure resulted in mesenchymal features, elevated proliferation rate, and were more motile, like the same cells that fused with MSC. We orthotopically grafted the parental head and neck cancer cells, those fused with MSC, or those exposed to MSC into the tongues of mice. The cancer cells originally incubated with MSC developed larger more aggressive tumors compared to the parental cell line. RNA sequencing analysis revealed the expression of genes associated with drug resistance in the cancer cells exposed to MSC compared to parental cancer cells. Strikingly, MSC exposed cancer cell lines developed paclitaxel resistance that could be maintained up to 30 d after the initial co-incubation period. The secretory profile of the MSC suggested IL-6 to be a potential mediator of epigenetic imprinting on the head and neck cancer cells. When the MSC-imprinted cancer cells were exposed to the demethylation agent, 5-aza-2'deoxycytidine, it restored the expression of the drug resistance genes to that of parental cells. This study demonstrated that the recognized recruitment of MSC to tumors could impart multiple protumorigenic properties including chemotherapy resistance like that observed in the relatively rare event of cancer/MSC cell fusion.

Human umbilical cord perivascular cells maintain regenerative traits following exposure to cyclophosphamide

Chemotherapies can cause germ cell depletion and gonadal failure. When injected post-chemotherapy, mesenchymal stromal cells (MSCs) from various sources have been shown to have regenerative effects in rodent models of chemotherapy-induced gonadal injury. Here, we evaluated two properties of a novel source of MSC, first trimester (FTM) human umbilical cord perivascular cells (HUCPVCs) (with increased regenerative potential compared to older sources), that may render them a promising candidate for chemotherapeutic gonadal injury prevention. Firstly, their ability to resist the cytotoxic effects of cyclophosphamide (CTX) in vitro, as compared to term HUCPVCs and bone marrow cells (BMSCs); and secondly, whether they prevent gonadal dysfunction if delivered prior to gonadotoxic therapy in vivo. BMSC, FTM HUCPVC, term HUCPVC, and control NTERA2 cells were treated with moderate (150 μmol/L) and high (300 μmol/L) doses of CTX in vitro. Viability, proliferative capacity, mesenchymal cell lineage markers and differentiation capacity, immunogenicity, and paracrine gene expression were assessed. CTX was administered to Wistar rats 2 days following an intra-ovarian injection of FTM HUCPVC. HUCPVC survival and ovarian follicle numbers were assessed using histological methods. We conclude that FTM HUCPVC maintain key regenerative properties following chemotherapy exposure and that pre-treatment with these cells may prevent CTX-induced ovarian damage in vivo. Therefore, HUCPVCs are promising candidates for fertility preservation.

Epigenetics of glioblastoma multiforme: From molecular mechanisms to therapeutic approaches

Glioblastoma multiforme (GBM) is the most common form of brain cancer and one of the most aggressive cancers found in humans. Most of the signs and symptoms of GBM can be mild and slowly aggravated, although other symptoms might demonstrate it as an acute ailment. However, the precise mechanisms of the development of GBM remain unknown. Due to the improvement of molecular pathology, current researches have reported that glioma progression is strongly connected with different types of epigenetic phenomena, such as histone modifications, DNA methylation, chromatin remodeling, and aberrant microRNA. Furthermore, the genes and the proteins that control these alterations have become novel targets for treating glioma because of the reversibility of epigenetic modifications. In some cases, gene mutations including P16, TP53, and EGFR, have been observed in GBM. In contrast, monosomies, including removals of chromosome 10, particularly q23 and q25-26, are considered the standard markers for determining the development and aggressiveness of GBM. Recently, amid the epigenetic therapies, histone deacetylase inhibitors (HDACIs) and DNA methyltransferase inhibitors have been used for treating tumors, either single or combined. Specifically, HDACIs are served as a good choice and deliver a novel pathway to treat GBM. In this review, we focus on the epigenetics of GBM and the consequence of its mutations. We also highlight various treatment approaches, namely gene editing, epigenetic drugs, and microRNAs to combat GBM.

Functional heterogeneity of mesenchymal stem cells from natural niches to culture conditions: implications for further clinical uses

Mesenchymal stem cells (MSC) are present in all organs and tissues. Several studies have shown the therapeutic potential effect of MSC or their derived products. However, the functional heterogeneity of MSC constitutes an important barrier for transferring these capabilities to the clinic. MSC heterogeneity depends on their origin (biological niche) or the conditions of potential donors (age, diseases or unknown factors). It is accepted that many culture conditions of the artificial niche to which they are subjected, such as O₂ tension, substrate and extracellular matrix cues, inflammatory stimuli or genetic manipulations can influence their resulting phenotype. Therefore, to attain a more personalized and precise medicine, a correct selection of MSC is mandatory, based on their functional potential, as well as the need to integrate all the existing information to achieve an optimal improvement of MSC features in the artificial niche.

Ex vivo-expanded autologous adipose tissue-derived stromal cells ensure enhanced fat graft retention in breast augmentation: A randomized controlled clinical trial

Autologous fat grafting and implant surgery are used for volume restoration in plastic surgery. With the aim of producing a treatment superior to current solutions, we report a randomized, controlled, data assessor‐blinded clinical trial comparing fat grafts enriched with ex vivo‐expanded autologous adipose‐derived stromal cells (ASCs) to nonenriched fat grafts in breast augmentation. The intervention group received ASC‐enriched fat grafts (≥20 × 10⁶ viable ex vivo‐expanded ASCs per milliliter fat), and the control group received conventional nonenriched fat grafts. Volume retention was measured by magnetic resonance imaging, and clinical photographs were taken simultaneously for outcome evaluation. ASC‐enriched fat grafts had significantly higher retention rates (mean = 80.2%) compared with conventional fat grafts (mean = 45.1%). Clinical photos showed statistically significant superior results in the intervention group, assessed by independent clinical experts. These results improve the prospects for using culture‐expanded ASCs in both reconstructive and cosmetic volume restoration and make the procedure an attractive alternative to conventional fat grafting and implants. This study is registered at www.ClinicalTrials.gov, number H‐16046960.

The voltage-gated proton channel hHv1 is functionally expressed in human chorion-derived mesenchymal stem cells

The voltage-gated proton channel Hv1 is widely expressed, among others, in immune and cancer cells, it provides an efficient cytosolic H⁺extrusion mechanism and regulates vital functions such as oxidative burst, migration and proliferation. Here we demonstrate the presence of human Hv1 (hHv1) in the placenta/chorion-derived mesenchymal stem cells (cMSCs) using RT-PCR. The voltage- and pH-dependent gating of the current is similar to that of hHv1 expressed in cell lines and that the current is blocked by 5-chloro-2-guanidinobenzimidazole (ClGBI) and activated by arachidonic acid (AA). Inhibition of hHv1 by ClGBI significantly decreases mineral matrix production of cMSCs induced by conditions mimicking physiological or pathological (inorganic phosphate, Pi) induction of osteogenesis. Wound healing assay and single cell motility analysis show that ClGBI significantly inhibits the migration of cMSCs. Thus, seminal functions of cMSCs are modulated by hHv1 which makes this channel as an attractive target for controlling advantages/disadvantages of MSCs therapy.

Intrathecal injection of bone marrow stromal cells attenuates neuropathic pain via inhibition of P2X4R in spinal cord microglia

Background

Neuropathic pain is one of the most debilitating of all chronic pain syndromes. Intrathecal (i.t.) bone marrow stromal cell (BMSC) injections have a favorable safety profile; however, results have been inconsistent, and complete understanding of how BMSCs affect neuropathic pain remains elusive.

Methods

We evaluated the analgesic effect of BMSCs on neuropathic pain in a chronic compression of the dorsal root ganglion (CCD) model. We analyzed the effect of BMSCs on microglia reactivity and expression of purinergic receptor P2X₄ (P2X₄R). Furthermore, we assessed the effect of BMSCs on the expression of transient receptor potential vanilloid 4 (TRPV4), a key molecule in the pathogenesis of neuropathic pain, in dorsal root ganglion (DRG) neurons.

Results

I.t. BMSC transiently but significantly ameliorated neuropathic pain behavior (37.6% reduction for 2 days). We found no evidence of BMSC infiltration into the spinal cord parenchyma or DRGs, and we also demonstrated that intrathecal injection of BMSC-lysates provides similar relief. These findings suggest that the analgesic effects of i.t. BMSC were largely due to the release of BMSC-derived factors into the intrathecal space. Mechanistically, we found that while i.t. BMSCs did not change TRPV4 expression in DRG neurons, there was a significant reduction of P2X₄R expression in the spinal cord microglia. BMSC-lysate also reduced P2X₄R expression in activated microglia in vitro. Coadministration of additional pharmacological interventions targeting P2X₄R confirmed that modulation of P2X₄R might be a key mechanism for the analgesic effects of i.t. BMSC.

Conclusion

Altogether, our results suggest that i.t. BMSC is an effective and safe treatment of neuropathic pain and provides novel evidence that BMSC’s analgesic effects are largely mediated by the release of BMSC-derived factors resulting in microglial P2X₄R downregulation.

Stem cell-derived extracellular vesicles: role in oncogenic processes, bioengineering potential, and technical challenges

Extracellular vesicles (EVs) are cellular-derived versatile transporters with a specialized property for trafficking a variety of cargo, including metabolites, growth factors, cytokines, proteins, lipids, and nucleic acids, throughout the microenvironment. EVs can act in a paracrine manner to facilitate communication between cells as well as modulate immune, inflammatory, regenerative, and remodeling processes. Of particular interest is the emerging association between EVs and stem cells, given their ability to integrate complex inputs for facilitating cellular migration to the sites of tissue injury. Additionally, stem cell-derived EVs can also act in an autocrine manner to influence stem cell proliferation, mobilization, differentiation, and self-renewal. Hence, it has been postulated that stem cells and EVs may work synergistically in the process of tissue repair and that dysregulation of EVs may cause a loss of homeostasis in the microenvironment leading to disease. By harnessing the property of EVs for delivery of small molecules, stem cell-derived EVs possess significant potential as a platform for developing bioengineering approaches for next-generation cancer therapies and targeted drug delivery methods. Although one of the main challenges of clinical cancer treatment remains a lack of specificity for the delivery of effective treatment options, EVs can be modified via genetic, biochemical, or synthetic methods for enhanced targeting ability of chemotherapeutic agents in promoting tumor regression. Here, we summarize recent research on the bioengineering potential of EV-based cancer therapies. A comprehensive understanding of EV modification may provide a novel strategy for cancer therapy and for the utilization of EVs in the targeting of oncogenic processes. Furthermore, innovative and emerging new technologies are shifting the paradigm and playing pivotal roles by continually expanding novel methods and materials for synthetic processes involved in the bioengineering of EVs for enhanced precision therapeutics.

Bidirectional and Opposite Effects of Naïve Mesenchymal Stem Cells on Tumor Growth and Progression

Cancer has long been considered as a heterogeneous population of uncontrolled proliferation of different transformed cell types. The recent findings concerning tumorigeneses have highlighted the fact that tumors can progress through tight relationships among tumor cells, cellular, and non-cellular components which are present within tumor tissues. In recent years, studies have shown that mesenchymal stem cells (MSCs) are essential components of non-tumor cells within the tumor tissues that can strongly affect tumor development. Several forms of MSCs have been identified within tumor stroma. Naïve (innate) mesenchymal stem cells (N-MSCs) derived from different sources are mostly recruited into the tumor stroma. N-MSCs exert dual and divergent effects on tumor growth through different conditions and factors such as toll-like receptor priming (TLR-priming), which is the primary underlying causes of opposite effects. Moreover, MSCs also have the contrary effects by various molecular mechanisms relying on direct cellto- cell connections and indirect communications through the autocrine, paracrine routes, and tumor microenvironment (TME).

Overall, cell-based therapies will hold great promise to provide novel anticancer treatments. However, the application of intact MSCs in cancer treatment can theoretically cause adverse clinical outcomes. It is essential that to extensively analysis the effective factors and conditions in which underlying mechanisms are adopted by MSCs when encounter with cancer.

The aim is to review the cellular and molecular mechanisms underlying the dual effects of MSCs followed by the importance of polarization of MSCs through priming of TLRs.

Mesenchymal Stem Cells Extract (MSCsE)-Based Therapy Alleviates Xerostomia and Keratoconjunctivitis Sicca in Sjogren's Syndrome-Like Disease

Sjogren’s syndrome (SS) is an autoimmune disease that manifests primarily in salivary and lacrimal glands leading to dry mouth and eyes. Unfortunately, there is no cure for SS due to its complex etiopathogenesis. Mesenchymal stem cells (MSCs) were successfully tested for SS, but some risks and limitations remained for their clinical use. This study combined cell- and biologic-based therapies by utilizing the MSCs extract (MSCsE) to treat SS-like disease in NOD mice. We found that MSCsE and MSCs therapies were successful and comparable in preserving salivary and lacrimal glands function in NOD mice when compared to control group. Cells positive for AQP5, AQP4, α-SMA, CK5, and c-Kit were preserved. Gene expression of AQP5, EGF, FGF2, BMP7, LYZ1 and IL-10 were upregulated, and downregulated for TNF-α, TGF-β1, MMP2, CASP3, and IL-1β. The proliferation rate of the glands and serum levels of EGF were also higher. Cornea integrity and epithelial thickness were maintained due to tear flow rate preservation. Peripheral tolerance was re-established, as indicated by lower lymphocytic infiltration and anti-SS-A antibodies, less BAFF secretion, higher serum IL-10 levels and FoxP3⁺ T_reg cells, and selective inhibition of B220⁺ B cells. These promising results opened new venues for a safer and more convenient combined biologic- and cell-based therapy.

Human skin-derived ABCB5+ stem cell injection improves liver disease parameters in Mdr2KO mice

Although liver transplantation is a potential effective cure for patients with end-stage liver diseases, this strategy has several drawbacks including high cost, long waiting list, and limited availability of liver organs. Therefore, stem cell-based therapy is presented as an alternative option, which showed promising results in animal models of acute and chronic liver injuries. ABCB5+ cells isolated from skin dermis represent an easy accessible and expandable source of homogenous stem cell populations. In addition, ABCB5+ cells showed already promising results in the treatment of corneal and skin injury. To date, the effect of these cells on liver injury is still unknown. In the current study, sixteen weeks old Mdr2KO mice were i.v. injected with 500,000 ABCB5+ cells using different experimental setups. The effects of cellular therapy on inflammation, fibrosis, apoptosis, and proliferation were analyzed in the collected liver tissues. Toxicity of ABCB5+ cells was additionally investigated in mice with partial liver resection. In vitro, the fibrosis- and inflammatory-modulating effects of supernatant from ABCB5+ cells were examined in the human hepatic stellate cell line (LX-2). Cell injections into fibrotic Mdr2KO mice as well as into mice upon partial liver resection have no signs of toxicity with regard to cell transformation, cellular damage, fibrosis or inflammation as compared to controls. We next investigated the effects of ABCB5+ cells on established biliary liver fibrosis in the Mdr2KO mice. ABCB5+ cells to some extent influenced the shape of the liver inflammatory response and significantly reduced the amount of collagen deposition, as estimated from quantification of sirius red staining. Furthermore, reduced apoptosis and enhanced death compensatory proliferation resulted from ABCB5+ cell transformation. The stem cells secreted several trophic factors that activated TGF-β family signaling in cultured LX-2 hepatic stellate cells (HSCs), therewith shaping cell fate to an αSMAhigh, Vimentinlow phenotype. Taken together, ABCB5+ cells can represent a safe and feasible strategy to support liver regeneration and to reduce liver fibrosis in chronic liver diseases.

An anticancer effect of umbilical cord-derived mesenchymal stem cell secretome on the breast cancer cell line

Nowadays, Mesenchymal stem cells (MSCs) have become one of the most attractive tools for treating tumors, due to their specific characteristics, the most prominent of which are tropism toward tumor. These cells will exert their effects through their secretion. In this study, our aim was to evaluate the anti-cancer effect of umbilical cord-derived mesenchymal cells (UCMSC) secretome, on MCF-7 tumor cells. MSCs were extracted from the umbilical cord of mothers, having normal delivery or cesarean section. After culture, the supernatants of these cells were collected and freeze-dried. The cytotoxic effect of freeze-dried secretome was examined at different concentrations on MCF-7 and the optimum concentrations (IC50) were calculated, using MTT assay. These results were confirmed by BrdU assay. The effect of induction of apoptosis of the MSC secretome on MCF-7 was determined, using annexin V/PI method by flow cytometry. The results of our study indicate that the isolation and growth time of UCMSCs of mothers who were naturally delivered was lower than those who received cesarean section. Co-culture studies showed that MSCs had cytotoxic effects on MCF-7 cells. The MSC secretome also showed cytotoxic effects on the MCF-7 cell line, this effect was mediated by induction of apoptosis, which was dose-dependent with an IC50 of 10 mg/mL.

The multifaceted role of mesenchymal stem cells in cancer

Mesenchymal stem cells (MSCs) are multipotent stem cells derived from the mesoderm that give rise to several mesenchymal lineages, including osteoblasts, adipocytes, chondrocytes and myocytes. Their potent ability to home to tumors coupled with their differentiation potential and immunosuppressive function positions MSCs as key regulators of tumor fate. Here we review the existing knowledge on the involvement of MSCs in multiple tumor-promoting processes, including angiogenesis, epithelial-mesenchymal transition, metastasis, immunosuppression and therapy resistance. We also discuss the clinical potential of MSC-based therapy for cancer.

Mesenchymal stromal cells for bone sarcoma treatment: Roadmap to clinical practice

Over the past few decades, there has been growing interest in understanding the molecular mechanisms of cancer pathogenesis and progression, as it is still associated with high morbidity and mortality. Current management of large bone sarcomas typically includes the complex therapeutic approach of limb salvage or sacrifice combined with pre- and postoperative multidrug chemotherapy and/or radiotherapy, and is still associated with high recurrence rates. The development of cellular strategies against specific characteristics of tumour cells appears to be promising, as they can target cancer cells selectively. Recently, Mesenchymal Stromal Cells (MSCs) have been the subject of significant research in orthopaedic clinical practice through their use in regenerative medicine. Further research has been directed at the use of MSCs for more personalized bone sarcoma treatments, taking advantage of their wide range of potential biological functions, which can be augmented by using tissue engineering approaches to promote healing of large defects. In this review, we explore the use of MSCs in bone sarcoma treatment, by analyzing MSCs and tumour cell interactions, transduction of MSCs to target sarcoma, and their clinical applications on humans concerning bone regeneration after bone sarcoma extraction.

Hematological Malignancy-Derived Small Extracellular Vesicles and Tumor Microenvironment: The Art of Turning Foes into Friends

Small extracellular vesicles (small EVs) are commonly released by all cells, and are found in all body fluids. They are implicated in cell to cell short- and long-distance communication through the transfer of genetic material and proteins, as well as interactions between target cell membrane receptors and ligands anchored on small EV membrane. Beyond their canonical functions in healthy tissues, small EVs are strategically used by tumors to communicate with the cellular microenvironment and to establish a proper niche which would ultimately allow cancer cell proliferation, escape from the immune surveillance, and metastasis formation. In this review, we highlight the effects of hematological malignancy-derived small EVs on immune and stromal cells in the tumor microenvironment.

Hydroxyurea-induced senescent peripheral blood mesenchymal stromal cells inhibit bystander cell proliferation of JAK2V617F-positive human erythroleukemia cells

Hydroxyurea (HU) is a nonalkylating antineoplastic agent used in the treatment of hematological malignancies. HU is a DNA replication stress inducer, and as such, it may induce a premature senescence-like cell phenotype; however, its repercussion on bystander cell proliferation has not been revealed so far. Our results indicate that HU strongly inhibited peripheral blood mesenchymal stromal cells (PBMSC) proliferation by cell cycle arrest in S phase, and that, consequently, PBMSC acquire senescence-related phenotypical changes. HU-treated PBMSC display increased senescence-associated β-galactosidase levels and p16^INK4 expression, as well as DNA damage response and genotoxic effects, evidenced by expression of γH2A.X and micronuclei. Moreover, HU-induced PBMSC senescence is mediated by increased reactive oxygen species (ROS) levels, as demonstrated by the inhibition of senescence markers in the presence of ROS scavenger N-acetylcysteine and NADPH oxidase inhibitor Apocynin. To determine the HU-induced bystander effect, we used the JAK2V617F-positive human erythroleukemia 92.1.7 (HEL) cells. Co-culture with HU-induced senescent PBMSC (HU-S-PBMSC) strongly inhibited bystander HEL cell proliferation, and this effect is mediated by both ROS and transforming growth factor (TGF)-β expression. Besides induction of premature senescence, HU educates PBMSC toward an inhibitory phenotype of HEL cell proliferation. Finally, our study contributes to the understanding of the role of HU-induced PBMSC senescence as a potential adjuvant in hematological malignancy therapies.

Mesenchymal Stromal Cells Derived from Normal Cervix and Cervical Cancer Tumors Increase CD73 Expression in Cervical Cancer Cells Through TGF-β1 Production

Mesenchymal stromal cells (MSCs) in the tumor microenvironment (TME) participate together with tumor cells to suppress antitumor effector cells through the production of immunosuppressive factors, such as transforming growth factor-beta 1 (TGF-β1). Furthermore, TGF-β1 can induce 5'-nucleotidase (CD73) expression in various cell types; this functional activity is associated with the production of adenosine (Ado), which is an immunosuppressive nucleoside. In this study, we provide evidence that coculture of MSCs derived from cervical tumors (CeCa-MSC) with CeCa tumor cells increases CD73 expression in tumor cells and the capacity of these cells to generate Ado in a MSC ratio-dependent manner. Interestingly, the increase in CD73 in the CeCa cell membrane corresponded to an increase in the TGF-β1 expression level in the tumor cells and the TGF-β1 content in the supernatants of the CeCa/CeCa-MSC cocultures. The addition of anti-hTGF-β neutralizing antibodies strongly reversed CD73 expression in the tumor cells. This phenomenon was not exclusive to CeCa-MSCs; coculture of MSCs derived from the normal cervix with CeCa cells produced similar results. These results suggest that the interaction of MSCs with CeCa tumor cells in the TME may condition higher TGF-β1 production to maintain an immunosuppressive status not only through the activity of this cytokine per se but also through its ability to induce CD73 expression in tumor cells and generate an immunosuppressive microenvironment rich in Ado.

BMSC Transplantation Aggravates Inflammation, Oxidative Stress, and Fibrosis and Impairs Skeletal Muscle Regeneration

Skeletal muscle contusion is one of the most common muscle injuries in sports medicine and traumatology. Bone marrow mesenchymal stem cell (BMSC) transplantation has been proposed as a promising strategy to promote skeletal muscle regeneration. However, the roles and underlying mechanisms of BMSCs in the regulation of skeletal muscle regeneration are still not completely clear. Here, we investigated the role of BMSC transplantation after muscle contusion. BMSCs were immediately transplanted into gastrocnemius muscles (GMs) following direct contusion. Comprehensive morphological and genetic analyses were performed after BMSC transplantation. BMSC transplantation exacerbated muscle fibrosis and inflammation, as evidenced by increased leukocyte and macrophage infiltration, increased inflammatory cytokines and chemokines, and increased matrix metalloproteinases. BMSC transplantation also increased muscle oxidative stress. Overall, BMSC transplantation aggravated inflammation, oxidative stress and fibrosis and impaired skeletal muscle regeneration. These results, shed new light on the role of BMSCs in regenerative medicine and indicate that caution is needed in the application of BMSCs for muscle injury.

A Role of Tumor-Released Exosomes in Paracrine Dissemination and Metastasis

Metastatic diffusion is thought to be a multi-step phenomenon involving the release of cells from the primary tumor and their diffusion through the body. Currently, several hypotheses have been put forward in order to explain the origin of cancer metastasis, including epithelial⁻mesenchymal transition, mutagenesis of stem cells, and a facilitating role of macrophages, involving, for example, transformation or fusion hybridization with neoplastic cells. In this paradigm, tumor-secreted extracellular vesicles (EVs), such as exosomes, play a pivotal role in cell communications, delivering a plethora of biomolecules including proteins, lipids, and nucleic acids. For their natural role in shuttling molecules, EVs have been newly considered a part of the metastatic cascade. They have a prominent role in preparing the so-called "tumor niches" in target organs. However, recent evidence has pointed out an even more interesting role of tumor EVs, consisting in their ability to induce malignant transformation in resident mesenchymal stem cells. All in all, in this review, we discuss the multiple involvements of EVs in the metastatic cascade, and how we can exploit and manipulate EVs in order to reduce the metastatic spread of malignant tumors.

Bioinstructive microparticles for self-assembly of mesenchymal stem Cell-3D tumor spheroids

3D multicellular tumor spheroids (3D-MCTS) that closely mimic in vitro the complex lung tumor microenvironment (TME) are highly desirable for screening innovative anti-cancer therapeutics. Despite significant improvements in mimicking lung TME, few models have combined tumor-infiltrating mesenchymal stem cells from bone marrow (hBM-MSCs) with heterotypic 3D tumor spheroid models containing ECM mimetic components. Herein, we engineered hybrid 3D-MCTS that combine, for the first time, A549:fibroblasts:hBM-MSCs in heterotypic tri-culture, with bioinstructive hyaluronan microparticles that act as tumor-ECM mimetics and as cell-anchoring hotspots. The obtained results indicated that 3D microspheres provided proper support for cells to self-assemble into compact 3D microtissues and promoted an increase in CD44 expression, emulating the presence of native-ECM hyaluronan. 3D-MCTS size and sphere-like morphology was reproducible and tri-culture models presented the characteristic solid tumors necrotic core. Mesenchymal stem cells tracking demonstrated that hBM-MSCs migrate to different regions in 3D microtumors mass exhibiting dynamic interactions with cancer cells and stromal fibroblasts, alike in human tumors. Importantly, doxorubicin administration revealed hBM-MSCs effect on cytotoxic responses in 3D tri-culture models and in dual cultures of hBM-MSCs:A549 at 10:1 ratio. Such findings evidence the relevance of including hBM-MSCs in combination with cancer-stromal fibroblasts in 3D in vitro tumor models and the importance to test different cell-to-cell ratios to mimic tumor heterogeneity. In addition, bioinstructive hyaluronan-microparticles were also effective as cell-agglomerating scaffolds and showed potential to be used as an enabling technology for including different ECM components in 3D in vitro models in the future.

Human mesenchymal stem cells in the tumour microenvironment promote ovarian cancer progression: the role of platelet-activating factor

Background

The tumour microenvironment conferred by mesenchymal stem cells (MSCs) plays a key role in tumour development and progression. We previously determined that platelet-activating factor receptor (PAFR) was overexpressed in ovarian cancer cells (OCCs) and that PAF can promote ovarian cancer progression via PAF/PAFR-mediated inflammatory signalling pathways. Evidence suggests that MSCs can secrete high concentrations of PAF. Here, we investigated the role of PAF/PAFR signalling in the microenvironment mediated by MSCs and OCCs and its effect on cancer progression.

Methods

The PAF concentrations in the culture media of MSCs, OCCs and co-cultured MSCs and OCCs were determined by ELISA. The effects of MSCs on OCCs in vitro were assessed on cells treated with conditioned medium (CM). The expression and phosphorylation of key proteins in the PAF/PAFR signalling pathway were evaluated. In vivo, MSCs/RFP and SKOV3 cells were co-administered at different proportions to nude mice by interscapular injection. Mice in the WEB2086 group were intraperitoneally injected with the PAFR antagonist WEB2086 at a dose of 1 mg/kg^.d for the duration of the animal experiments. Tumour progression was observed, and the weight and survival time of mice were measured. The PAF concentration in peripheral and tumour site blood was determined by ELISA.

Results

High concentrations of PAF were detected in CM from MSCs and MSCs co-cultured with OCCs. Both types of medium promoted non-mucinous OCC proliferation and migration but had no effect on mucinous-type OCCs. These effects could be blocked by PAFR inhibitors. The expression and phosphorylation of key proteins in the PAF/PAFR pathway significantly increased upon treatment with PAF and MSC-CM. In vivo, the tumour volume was larger following co-injection of SKOV3 cells and MSCs/RFP than following injection of SKOV3 cells alone. The tumour-promoting effect of MSCs/RFP was blocked by the PAFR antagonist WEB2086. Serum PAF concentrations significantly increased in co-injected mice.

Conclusion

Our results suggest that the tumour-promoting effect of MSCs on OCCs via their cross-talk in the tumour microenvironment was, at least in part, mediated by the PAF/PAFR pathway, suggesting a new target for the treatment of ovarian cancer.

The interplay between adipose-derived stem cells and bladder cancer cells

Tissue engineering approaches offer alternative strategies for urinary diversion after radical cystectomy. Possible triggering of cancer recurrence remains, however, a significant concern in the application of stem-cell based therapies for oncological patients. Soluble mediators secreted by stem cells induce tissue remodelling effects, but may also promote cancer cells growth and metastasis. We observed a substantial increase in the concentration of IL-6 and IL-8 in the secretome of adipose-derived stem cells (ASCs) co-cultured with bladder cancer cells. Concentrations of GM-CSF, MCP-1 and RANTES were also elevated. Bioactive molecules produced by ASCs increased the viability of 5637 and HT-1376 cells by respectively 15.4% and 10.4% (p < 0.0001). A trend in reduction of adhesion to ECM components was also noted, even though no differences in β-catenin expression were detected. When HT-1376 cells were co-cultured with ASCs their migration and invasion increased by 24.5% (p < 0.0002) and 18.2% (p < 0.002). Expression of p-ERK1/2 increased in 5637 cells (2.2-fold; p < 0.001) and p-AKT in HB-CLS-1 cells (2.0-fold; p < 0.001). Our results confirm that ASCs crosstalk with bladder cancer cells in vitro what influences their proliferation and invasive properties. Since ASCs tropism to tumour microenvironment is well documented their application towards post-oncologic reconstruction should be approached with caution.

Improved therapeutic potential of MSCs by genetic modification

Mesenchymal stem cells (MSCs), well-studied adult stem cells in various tissues, possess multi-lineage differentiation potential and anti-inflammatory properties. MSCs have been approved to regenerate lineage-specific cells to replace injured cells in tissues. MSCs are approved to treat inflammatory diseases. With the discovery of genes important for the repair of damaged tissues, MSCs genetically modified by such genes hold improved therapeutic potential. In this review, we summarised the uses of genetically modified MSCs to treat different diseases, including bone diseases, cardiovascular diseases, autoimmune diseases, central nervous system disorders, and cancer. To better understand the exact role of genetically modified MSCs, key mechanisms determining, which genes are selected to be used for modifying MSCs and improvements in post-genetic modification are discussed. Therapeutic benefits enhanced by genetic modifications are to be documented by further clinical studies.

Detection of endogenously circulating mesenchymal stem cells in human cancer patients

Mesenchymal stem cells (MSCs) can play a vital role in tumor progression and anticancer therapy response, as demonstrated by various in vitro and in vivo model systems. Their ability to home to developing tumors and modulate the tumor microenvironment, by suppressing T-cell responses and contributing to the tumor stroma, is suggested to have a significant impact on disease progression, metastasis formation, and therapy response. Most evidence, however, is derived from artificial models using exogenously administered MSCs. The contribution of endogenous MSCs to tumor progression is currently unclear. Furthermore, few studies have been conducted in humans. A prospective biomarker study was therefore undertaken in 40 human cancer patients and 10 healthy controls of similar age, aimed at (i) exploring and quantifying circulating MSC levels in healthy volunteers and patients with advanced malignancies, (ii) determining the variability of MSC levels between healthy volunteers and cancer patients with different histologic tumor types, and (iii) exploring biomarkers associated with MSC levels. Significantly increased levels of circulating MSC-like cells were observed in cancer patients when compared to healthy individuals (1.72 fold difference, 95% CI 1.03-2.81%, p = 0.03). In addition, prior systemic therapy was associated with a significant increase in MSC-like cells (1.73 fold difference, 95% CI 1.02-2.95, p = 0.04). These results indicate that the amount of endogenously circulating MSCs in humans is increased in response to cancer, and that systemic anticancer treatment can influence MSC levels. Further research is needed to determine whether MSCs have a predictive value.

Revisiting the dynamic cancer stem cell model: Importance of tumour edges

The lack of an effective treatment against cancer is not only due to its huge heterogeneity, but also to the fact that we don't have an answer to the question on how cancer originates. Among the proposed models to explain the development of cancer, the hierarchical model has been widely accepted. Nevertheless, this model fails to explain several experimental observations such as the cancer stem cells (CSCs) location inside a tumour or the differences between primary and metastatic tumours. Moreover, increasing evidence shows that the CSC phenotype is not a rigid state. Here, we present a critical review on the assumed tumour development models emphasizing the relevance of the dynamic and changing nature of cancer and the CSCs population in which the tumour microenvironment plays a crucial role and we propose a new model of tumour origin that could have an impact on new therapeutic strategies.

Whole snake venoms: Cytotoxic, anti-metastatic and antiangiogenic properties

Currently, biological and organic substances are screened in order to find a new generation of therapeutics active against cancer. Previous research has identified promising candidate peptides in snake venom. In this study, venoms from different snake species (Naja annulifera, Naja kaouthia, Ophiophagus hannah and Echis carinatus) were screened for potential anti-cancer properties using pancreatic tumour cells as the assay system. The cells were incubated with venom and then subjected to the following analyses: (i) in vitro cell death (ii) in vitro migration (iii) in vivo dissemination and (iv) in vivo angiogenesis. For the in vivo assays, the cells, after incubation and labelling, were transplanted into the yolk sac of zebrafish embryos for motility and angiogenesis. The results showed strong effects in cells treated with venoms from Ophiophagus hannah and Echis carinatus in the in vitro assays. In the in vivo assays, venom derived from Ophiophagus hannah had the most potent effects with respect to angiogenesis. These venoms might therefore be considered as candidates for further studies.

Promoter Methylation Status of Survival-Related Genes in MOLT- 4 Cells Co-Cultured with Bone Marrow Mesenchymal Stem Cells under Hypoxic Conditions

OBJECTIVES

DNA methylation is a well-studied epigenetic mechanism that is a potent arm of the gene expression controlling machinery. Since the hypoxic situation and the various cells of bone marrow microenvironment, e.g. mesenchymal stem cells, play a role in the in vivo and in vitro biology of leukemic cells, we decided to study the effects of hypoxia and mesenchymal stem cells (MSCs) on the promoter methylation pattern of BAX and BCL2 genes.

MATERIALS AND METHODS

In this experimental study, the co-culture of MOLT-4 cells with MSCs and treatment with CoCl₂ was done during 6, 12, and 24 hour periods. Total DNA was extracted using commercial DNA extraction kits, and sodium bisulfite (SBS) treatment was performed on the extracted DNA. Methylation specific polymerase chain reaction (MSP) was used to evaluate the methylation status of the selected genes' promoter regions.

RESULTS

The BAX and BCL2 promoters of untreated MOLT-4 cells were in partial methylated and fully unmethylated states, respectively. After incubating the cancer cells with CoCl₂ and MSCs, the MSP results after 6, 12, and 24 hours were the same as untreated MOLT-4 cells. In other words, the exposure of MOLT-4 cells to the hypoxia-mimicry agent and MSCs in various modes and different time frames showed that these factors have exerted no change on the methylation signature of the studied fragments from the promoter region of the mentioned genes.

CONCLUSIONS

Hypoxia and MSCs actually have no notable effect on the methylation status of the promoters of BAX and BCL2 in the specifically studied regions. DNA methylation is probably not the main process by which MSCs and CoCl₂ induced hypoxia regulate the expression of these genes. Finally, we are still far from discovering the exact functional mechanisms of gene expression directors, but these investigations can provide new insights into this field for upcoming studies.

Mesenchymal stem cells promote cell invasion and migration and autophagy-induced epithelial-mesenchymal transition in A549 lung adenocarcinoma cells

Mesenchymal stem cells (MSCs) are recruited into the tumour microenvironment and promote tumour growth and metastasis. Tumour microenvironment-induced autophagy is considered to suppress primary tumour formation by impairing migration and invasion. Whether these recruited MSCs regulate tumour autophagy and whether autophagy affects tumour growth are controversial. Our data showed that MSCs promote autophagy activation, reactive oxygen species production, and epithelial-mesenchymal transition (EMT) as well as increased migration and invasion in A549 cells. Decreased expression of E-cadherin and increased expression of vimentin and Snail were observed in A549 cells cocultured with MSCs. Conversely, MSC coculture-mediated autophagy positively promoted tumour EMT. Autophagy inhibition suppressed MSC coculture-mediated EMT and reduced A549 cell migration and invasion slightly. Furthermore, the migratory and invasive abilities of A549 cells were additional increased when autophagy was further enhanced by rapamycin treatment. Taken together, this work suggests that microenvironments containing MSCs can promote autophagy activation for enhancing EMT; MSCs also increase the migratory and invasive abilities of A549 lung adenocarcinoma cells. Mesenchymal stem cell-containing microenvironments and MSC-induced autophagy signalling may be potential targets for blocking lung cancer cell migration and invasion.