TGF-β and mesenchymal stromal cells in regenerative medicine, autoimmunity and cancer

Nerve growth factor (NGF) and NGF receptors in mesenchymal stem/stromal cells: Impact on potential therapies

Mesenchymal stem/stromal cells (MSCs) are promising for the treatment of degenerative diseases and traumatic injuries. However, MSC engraftment is not always successful and requires a strong comprehension of the cytokines and their receptors that mediate the biological behaviors of MSCs. The effects of nerve growth factor (NGF) and its two receptors, TrkA and p75NTR, on neural cells are well studied. Increasing evidence shows that NGF, TrkA, and p75NTR are also involved in various aspects of MSC function, including their survival, growth, differentiation, and angiogenesis. The regulatory effect of NGF on MSCs is thought to be achieved mainly through its binding to TrkA. p75NTR, another receptor of NGF, is regarded as a novel surface marker of MSCs. This review provides an overview of advances in understanding the roles of NGF and its receptors in MSCs as well as the effects of MSC‐derived NGF on other cell types, which will provide new insight for the optimization of MSC‐based therapy.

Next Generation Imaging Techniques to Define Immune Topographies in Solid Tumors

In recent years, cancer immunotherapy experienced remarkable developments and it is nowadays considered a promising therapeutic frontier against many types of cancer, especially hematological malignancies. However, in most types of solid tumors, immunotherapy efficacy is modest, partly because of the limited accessibility of lymphocytes to the tumor core. This immune exclusion is mediated by a variety of physical, functional and dynamic barriers, which play a role in shaping the immune infiltrate in the tumor microenvironment. At present there is no unified and integrated understanding about the role played by different postulated models of immune exclusion in human solid tumors. Systematically mapping immune landscapes or "topographies" in cancers of different histology is of pivotal importance to characterize spatial and temporal distribution of lymphocytes in the tumor microenvironment, providing insights into mechanisms of immune exclusion. Spatially mapping immune cells also provides quantitative information, which could be informative in clinical settings, for example for the discovery of new biomarkers that could guide the design of patient-specific immunotherapies. In this review, we aim to summarize current standard and next generation approaches to define Cancer Immune Topographies based on published studies and propose future perspectives.

Proliferation and tenogenic differentiation of bone marrow mesenchymal stem cells in a porous collagen sponge scaffold

BACKGROUND

Collagen is one of the most commonly used natural biomaterials for tendon tissue engineering. One of the possible practical ways to further enhance tendon repair is to combine a porous collagen sponge scaffold with a suitable growth factor or cytokine that has an inherent ability to promote the recruitment, proliferation, and tenogenic differentiation of cells. However, there is an incomplete understanding of which growth factors are sufficient and optimal for the tenogenic differentiation of rat bone marrow mesenchymal stem cells (BMSCs) in a collagen sponge-based 3D culture system.

AIM

To identify one or more ideal growth factors that benefit the proliferation and tenogenic differentiation of rat BMSCs in a porous collagen sponge scaffold.

METHODS

We constructed a 3D culture system based on a type I collagen sponge scaffold. The surface topography of the collagen sponge scaffold was observed by scanning electron microscopy. Primary BMSCs were isolated from Sprague-Dawley rats. Cell survival on the surfaces of the scaffolds with different growth factors was assessed by live/dead assay and CCK-8 assay. The mRNA and protein expression levels were confirmed by quantitative real-time polymerase chain reaction and Western blot, respectively. The deposited collagen was assessed by Sirius Red staining.

RESULTS

Transforming growth factor β1 (TGF-β1) showed great promise in the tenogenic differentiation of BMSCs compared to growth differentiation factor 7 (GDF-7) and insulin-like growth factor 1 (IGF-1) in both the 2D and 3D cultures, and the 3D culture enhanced the differentiation of BMSCs into tenocytes well beyond the level of induction in the 2D culture after TGF-β1 treatment. In the 2D culture, the proliferation of the BMSCs showed no significant changes compared to the control group after TGF-β1, IGF-1, or GDF-7 treatment. However, TGF-β1 and GDF-7 could increase the cell proliferation in the 3D culture. Strangely, we also found more dead cells in the BMSC-collagen sponge constructs that were treated with TGF-β1. Moreover, TGF-β1 promoted more collagen deposition in both the 2D and 3D cultures.

CONCLUSION

Collagen sponge-based 3D culture with TGF-β1 enhances the responsiveness of the proliferation and tenogenic differentiation of rat BMSCs.

Recent trends in cancer therapy: A review on the current state of gene delivery

Cancer treatment has been always considered one of the most critical and vital themes of clinical issues. Many approaches have been developed, depending on the type and the stage of tumor. Gene therapy has the potential to revolutionize different cancer therapy. With the advent of recent bioinformatics technologies and genetic science, it become possible to identify, diagnose and determine the potential treatment using the technology of gene delivery. Several approaches have been developed and experimented in vitro and vivo for cancer therapy including: naked nucleic acids based therapy, targeting micro RNAs, oncolytic virotherapy, suicide gene based therapy, targeting telomerase, cell mediated gene therapy, and CRISPR/Cas9 based therapy. In this review, we present a straightforward introduction to cancer biology and occurrence, highlighting different viral and non-viral gene delivery systems for gene therapy and critically discussed the current and various strategies for cancer gene therapy.

Prolonged lifespan in a spontaneously hypertensive rat (stroke prone) model following intravenous infusion of mesenchymal stem cells

Intravenous infusion of mesenchymal stem cells (MSCs) has been reported to provide therapeutic efficacy via microvascular remodeling in a spontaneously hypertensive rat. In this study, we demonstrate that intravenous infusion of MSCs increased the survival rate in a spontaneously hypertensive (stroke prone) rat model in which organs including kidney, brain, heart and liver are damaged during aging due to spontaneous hypertension. Gene expression analysis indicated that infused MSCs activates transforming growth factor-β1-smad3/forkhead box O1 signaling pathway. Renal dysfunction was recovered after MSC infusion. Collectively, intravenous infusion of MSC may extend lifespan in this model system.

GARP promotes the proliferation and therapeutic resistance of bone sarcoma cancer cells through the activation of TGF-β

Sarcomas are mesenchymal cancers with poor prognosis, representing about 20% of all solid malignancies in children, adolescents, and young adults. Radio- and chemoresistance are common features of sarcomas warranting the search for novel prognostic and predictive markers. GARP/LRRC32 is a TGF-β-activating protein that promotes immune escape and dissemination in various cancers. However, if GARP affects the tumorigenicity and treatment resistance of sarcomas is not known. We show that GARP is expressed by human osteo-, chondro-, and undifferentiated pleomorphic sarcomas and is associated with a significantly worse clinical prognosis. Silencing of GARP in bone sarcoma cell lines blocked their proliferation and induced apoptosis. In contrast, overexpression of GARP promoted their growth in vitro and in vivo and increased their resistance to DNA damage and cell death induced by etoposide, doxorubicin, and irradiation. Our data suggest that GARP could serve as a marker with therapeutic, prognostic, and predictive value in sarcoma. We propose that targeting GARP in bone sarcomas could reduce tumour burden while simultaneously improving the efficacy of chemo- and radiotherapy.

A comparative analysis of immunomodulatory genes in two clonal subpopulations of CD90+ amniocytes isolated from human amniotic fluid

OBJECT

Immunosuppressive and immunomodulatory activity of mesenchymal stem cells derived from different sources, such as placental membranes, umbilical cord, and amniotic fluid has been proved. The heterogeneous nature of human amniocytes have been confirmed due to different clonal subpopulations found in amniotic fluid. The aim of this study was to investigate a 17-gene panel of immunomodulatory markers in two clonal subpopulations of CD90⁺ amniocytes, divided based on morphology into epithelioid and fibroblastoid cells.

METHOD

Semi-quantitative RT-PCR was used to study the expression of the chosen genes. Flow cytometry analysis confirmed the non-hematopoietic mesenchymal origin of isolated cells, based on lacking the hematopoietic marker of CD31, and the presence of mesenchymal marker of CD90 (both on more than 90% of cells).

RESULTS

Our results showed that besides growth characteristics, the two cell groups were different in expressional profile, so that, fibroblastoid clones displayed higher level of immunosuppression genes as well as mesenchymal surface marker of CD90 compared to epithelioid ones. Our previous investigation on these clones showed that epithelioid cells have a more potential to express the pluripotency genes. It seems there is an inverse relationship between genes associated with immunosuppression and pluripotency.

CONCLUSION

Although many reports have been published regarding the immunosuppressive properties of fetal stem cells, but few studies to date have explained whether the stemness state of human amniocytes may affect their immunosuppressive potential. Further study on amniocytes, which often has self-renewal ability and high immunomodulatory potential, can help to understand the details of this relationship.

The effect of bone marrow mesenchymal stem cells on highly metastatic MHCC97-H hepatocellular carcinoma cells following OPN and TGFβ1 gene silencing

The metastatic behavior of hepatocellular carcinoma (HCC) is one of the key factors that leads to poor prognosis. The aim of the current study was to determine the changes in metastasis and the proliferation potential of bone marrow mesenchymal stem cells (BMSCs) in high metastatic potential hepatocellular carcinoma (MHCC97-H) following gene silencing. The osteopontin (OPN) and transforming growth factor-β (TGFβ₁ ) genes, which are associated with metastasis and tumor proliferation, were silenced in MHCC97-H cells. Transwell assays were used to evaluate the migration of MHCC97-H cells in vitro. Additionally, a murine model of MHCC97-H lung metastasis was established. Following OPN and TGFβ₁ silencing, the migration of MHCC97-H cells was significantly reduced following BMSC intervention (P<0.01). Furthermore, there were few MHCC97-H cells in the lung tissues of the OPN- and TGFβ₁ -silenced animals, and their integrated optical density (IOD) value was significantly lower compared with controls (P<0.05). Immunofluorescence of lung metastasis in the MHCC97-H model revealed that there was no significant difference in the IOD value of integrin α_vβ₃ expression in the OPN- and TGFβ₁ -silenced groups compared with controls (P>0.05). The metastasis and proliferation potential of MHCC97-H following BMSC intervention were significantly reduced in vitro and in vivo, especially in the TGFβ₁-silenced group. The decrease in the metastatic potential in gene-silenced MHCC97-H cells was not associated with integrin α_vβ₃ expression. Therefore, OPN and TGFβ₁ may be potential targets for HCC treatment, and TGFβ₁ may have a higher therapeutic potential for BMSC intervention.

Exosome: A New Player in Translational Nanomedicine

Summary: Exosomes are extracellular vesicles released by the vast majority of cell types both in vivo and ex vivo, upon the fusion of multivesicular bodies (MVBs) with the cellular plasma membrane. Two main functions have been attributed to exosomes: their capacity to transport proteins, lipids and nucleic acids between cells and organs, as well as their potential to act as natural intercellular communicators in normal biological processes and in pathologies. From a clinical perspective, the majority of applications use exosomes as biomarkers of disease. A new approach uses exosomes as biologically active carriers to provide a platform for the enhanced delivery of cargo in vivo. One of the major limitations in developing exosome-based therapies is the difficulty of producing sufficient amounts of safe and efficient exosomes. The identification of potential proteins involved in exosome biogenesis is expected to directly cause a deliberate increase in exosome production. In this review, we summarize the current state of knowledge regarding exosomes, with particular emphasis on their structural features, biosynthesis pathways, production techniques and potential clinical applications.

Mesenchymal Stromal Cells and Exosomes: Progress and Challenges

Due to their robust immunomodulatory capabilities, mesenchymal stem/stromal cells (MSCs) have been used as a cellular therapy for a number of human diseases. Part of the mechanism of action of MSCs is the production of extracellular vesicles (EVs) that contain proteins, nucleic acids, and lipids that transmit signals to recipient cells that change their biologic behavior. This review briefly summarizes the development of MSCs as a treatment for human diseases as well as describes our present understanding of exosomes; how they exert their effects on target cells, and how they are differentiated from other EVs. The current treatment paradigm for acute radiation syndrome (ARS) is discussed, and how MSCs and MSC derived exosomes are emerging as treatment options for treating patients after radiation exposure. Other conditions such as graft-versus-host disease and cardiovascular disease/stroke are discussed as examples to highlight the immunomodulatory and regenerative capacity of MSC-exosomes. Finally, a consideration is given to how these cell-based therapies could possibly be deployed in the event of a catastrophic radiation exposure event.

Promotion of Proangiogenic Secretome from Mesenchymal Stromal Cells via Hierarchically Structured Biodegradable Microcarriers

Adipose-derived mesenchymal stromal cells (AdMSC) release numerous soluble factors capable of stimulating angiogenesis. Improved methods for delivering these cells to maximize their potency are now sought that ideally they retain viable cells in the target tissue while promoting the secretion of angiogenic factors. Substrate surface topography is a parameter that can be used to manipulate the behavior of AdMSC but challenges exist with translating this parameter into materials compatible with minimally invasive delivery into tissues for in situ delivery of the angiogenic secretome. The current study investigates three compositions of hierarchically structured, porous biodegradable microcarriers for the culture of AdMSC and the influence of their surface topographies on the angiogenic secretome. All three compositions perform well as cell microcarriers in xeno-free conditions. The attached AdMSC retain their capacity for subsequent trilineage differentiation. The secretome of AdMSC attached to the microcarriers consists of multiple proangiogenic factors, including significantly elevated levels of vascular endothelial growth factor, which stimulates angiogenesis in vitro. The unique properties of hierarchically structured, porous biodegradable microcarriers investigated in this study offer a radically transformative approach for achieving targeted in vivo delivery of AdMSC and enhancing the potency of their proangiogenic activity to induce neovascularization in ischemic tissue.

GARP is a key molecule for mesenchymal stromal cell responses to TGF-β and fundamental to control mitochondrial ROS levels

Multipotent mesenchymal stromal cells (MSCs) have emerged as a promising cell therapy in regenerative medicine and for autoimmune/inflammatory diseases. However, a main hurdle for MSCs-based therapies is the loss of their proliferative potential in vitro. Here we report that glycoprotein A repetitions predominant (GARP) is required for the proliferation and survival of adipose-derived MSCs (ASCs) via its regulation of transforming growth factor-β (TGF-β) activation. Silencing of GARP in human ASCs increased their activation of TGF-β which augmented the levels of mitochondrial reactive oxygen species (mtROS), resulting in DNA damage, a block in proliferation and apoptosis. Inhibition of TGF-β signaling reduced the levels of mtROS and DNA damage and restored the ability of GARP-/low ASCs to proliferate. In contrast, overexpression of GARP in ASCs increased their proliferative capacity and rendered them more resistant to etoposide-induced DNA damage and apoptosis, in a TGF-β-dependent manner. In summary, our data show that the presence or absence of GARP on ASCs gives rise to distinct TGF-β responses with diametrically opposing effects on ASC proliferation and survival.

Emerging Therapeutic Potential of Mesenchymal Stem/Stromal Cells in Preeclampsia

PURPOSE OF REVIEW

Preeclampsia is a dangerous pregnancy condition affecting both the mother and offspring. It is a multifactorial disease with poorly understood pathogenesis, lacking effective treatments. Maternal immune response, inflammation and oxidative stress leading to endothelial dysfunction are the most prominent pathogenic processes implicated in preeclampsia development. Here, we give a detailed overview of the therapeutic applications and mechanisms of mesenchymal stem/stromal cells (MSCs) as a potential new treatment for preeclampsia.

RECENT FINDINGS

MSCs have gained growing attention due to low immunogenicity, easy cultivation and expansion in vitro. Accumulating evidence now suggests that MSCs act primarily through their secretomes facilitating paracrine signalling that leads to potent immunomodulatory, pro-angiogenic and regenerative therapeutic effects. MSCs have been studied in different animal models of preeclampsia demonstrating promising result, which support further investigations into the therapeutic effects and mechanisms of MSC-based therapies in preeclampsia, steering these therapies into clinical trials.

Mesenchymal stem cells induced regulatory dendritic cells from hemopoietic progenitor cells through Notch pathway and TGF-β synergistically

Mesenchymal stem cells (MSCs) are one of the attractive candidates in regenerative medicine of many clinical applications because of their low immunogenicity and immunomodulatory property. Our previous studies provided that mouse bone marrow-derived Sca-1⁺MSCs could drive the differentiation of regulatory DC (regDCs) (Scal-1⁺ BM-MSC-driven DC [sBM-DCs]) from hemopoietic progenitor cells (HPCs) and the Notch pathway played a critical role in maintaining the immunomodulatory property. However, the detailed mechanisms of their immunoregulatory capacity are not fully defined. In the present study, we show that BM-MSCs expressed high levels of Jagged 1 while sBM-DCs expressed high levels of Notch1. Jagged1 expressed on the surface of BM-MSCs initiated Notch signaling to maintain the immunomodulatory property of the sBM-DCs. The level of TGF-β is high in MSCs, either alone or coculture with HPCs medium. TGF-β plays a vital role in the proliferation and differentiation of sBM-DCs and inhibition of TGF-β reduce the number and increase the percentage of CD34, CD117, CD135 of generation cells. Thus, MSCs induced the regDCs from HPCs via the Notch signaling pathway and TGF-β synergistically. This study further broadens our understanding of the immunomodulatory mechanism and the potential therapeutic efficacy of MSCs.

Nodal promotes the malignancy of non-small cell lung cancer (NSCLC) cells via activation of NF-κB/IL-6 signals

Non-small cell lung cancer (NSCLC) is one of the leading causes of cancer deaths worldwide. Understanding the mechanisms responsible for the malignancy of NSCLC cells is important for therapy and drug development. Nodal, an important embryonic morphogen, has been reported to modulate tumorigenesis. We found that Nodal can trigger the proliferation of NSCLC cells and decrease the sensitivity to doxorubicin (Dox) and cisplatin (CDDP) treatment. Targeted inhibition of Nodal can suppress the proliferation of NSCLC cells. Among the measured cytokines, Nodal can increase the expression of interleukin-6 (IL-6) and vascular endothelial growth factor A (VEGFA) in NSCLC cells. Inhibition of IL-6, while not VEGFA, attenuated Nodal induced cell proliferation, suggesting the essential roles of IL-6 in Nodal induced malignancy of NSCLC cells. Nodal can trigger the phosphorylation, nuclear translocation and transcriptional activities of p65, the key signal transducer of NF-κB. This was due to the fact that Nodal can increase the phosphorylation of IKKβ/IκBα. The inhibitor of IKKβ abolished Nodal induced activation of p65 and expression of IL-6. Collectively, we found that Nodal can increase the proliferation and decrease chemosensitivity of NSCLC cells via regulation of NF-κB/IL-6 signals. It indicated that Nodal might be a potential therapeutic target for NSCLC treatment.

Novel copolymers drive differentiation of human adipose derived stem cells towards chondrocytes and osteoblasts identified by high-throughput approach

Human adipose derived stem cells (hASCs) were seeded onto polymer microarrays that had been fabricated using a variety of acrylate monomers to discover novel substrates that induced differentiation towards chondrocytes and osteoblasts. Flow cytometric analysis showed that both CD105 and CD49d positive hASCs increased rapidly with passage number on the lead polymers, while quantitative PCR analysis showed that the substrate synthesized from methacryloxyethyltrimethyl ammonium chloride, N,N-diethylaminoethyl methacrylate and cyclohexyl methacrylate enhanced chondrogenesis and osteogenensis some 4 and 25 times respectively in terms of the expression of SOX9 and ALP in differentiated stem cells. These copolymers substrates thus have great potential for application in the purification, generation and expansion of defined hASC's and the controlled differentiation of of cells for possible clinical application.

Dental Pulp Stem Cells: Advances to Applications

Dental pulp stem cells (DPSCs) have a high capacity for differentiation and the ability to regenerate a dentin/pulp-like complex. Numerous studies have provided evidence of DPSCs’ differentiation capacity, such as in neurogenesis, adipogenesis, osteogenesis, chondrogenesis, angiogenesis, and dentinogenesis. The molecular mechanisms and functions of DPSCs’ differentiation process are affected by growth factors and scaffolds. For example, growth factors such as basic fibroblast growth factor (bFGF), transforming growth factor-β (TGF-β), nerve growth factor (NGF), platelet-derived growth factor (PDGF), and bone morphogenic proteins (BMPs) influence DPSC fate, including in differentiation, cell proliferation, and wound healing. In addition, several types of scaffolds, such as collagen, hydrogel, decellularized bioscaffold, and nanofibrous spongy microspheres, have been used to characterize DPSC cellular attachment, migration, proliferation, differentiation, and functions. An appropriate combination of growth factors and scaffolds can enhance the differentiation capacity of DPSCs, in terms of optimizing not only dental-related expression but also dental pulp morphology. For a cell-based clinical approach, focus has been placed on the tissue engineering triad [cells/bioactive molecules (growth factors)/scaffolds] to characterize DPSCs. It is clear that a deep understanding of the mechanisms of stem cells, including their aging, self-renewal, microenvironmental homeostasis, and differentiation correlated with cell activity, the energy for which is provided from mitochondria, should provide new approaches for DPSC research and therapeutics. Mitochondrial functions and dynamics are related to the direction of stem cell differentiation, including glycolysis, oxidative phosphorylation, mitochondrial metabolism, mitochondrial transcription factor A (TFAM), mitochondrial elongation, and mitochondrial fusion and fission proteins. This review summarizes the effects of major growth factors and scaffolds for regenerating dentin/pulp-like complexes, as well as elucidating mitochondrial properties of DPSCs for the development of advanced applications research.

TGF-ß1 Induces Changes in the Energy Metabolism of White Adipose Tissue-Derived Human Adult Mesenchymal Stem/Stromal Cells In Vitro

Adipose tissue plays an active role in the regulation of the body’s energy balance. Mesenchymal stem/stromal cells from adipose tissue (adMSC) are the precursor cells for repair and adipogenesis. Since the balance of the differentiation state of adipose tissue-resident cells is associated with the development of various diseases, the examination of the regulation of proliferation and differentiation of adMSC might provide new therapeutic targets. Transforming growth factor-β1 (TGF-ß1) is synthetized by many cell types and is involved in various biological processes. Here, we investigated the effects of different concentrations of TGF-ß1 (1–10 ng/mL) on adMSC proliferation, metabolic activity, and analyzed the gene expression data obtained from DNA microarrays by bioinformatics. TGF-ß1 induced the concentration- and time-dependent increase in the cell number of adMSC with simultaneously unchanged cell cycle distributions. The basal oxygen consumption rates did not change significantly after TGF-ß1 exposure. However, glycolytic activity was significantly increased. The gene expression analysis identified 3275 differentially expressed genes upon exposure to TGF-ß1. According to the pathway enrichment analyses, they also included genes associated with energy metabolism. Thus, it was shown that TGF-ß1 induces changes in the energy metabolism of adMSC. Whether these effects are of relevance in vivo and whether they contribute to pathogenesis should be addressed in further examinations.

The Paradox of Cancer Immune Exclusion: Immune Oncology Next Frontier

Checkpoint inhibitor therapy (CIT) has revolutionized cancer treatment but it has also reached a standstill when an absent dialog between cancer and immune cells makes it irrelevant. This occurs with high prevalence in the context of "immune silent" and, even perhaps, "immune-excluded" tumors. The latter are characterized by T cells restricted to the periphery of cancer nests. Since in either case T cells do not come in direct contact with most cancer cells, CIT rests immaterial. Adoptive cell therapy (ACT), may also be affected by limited access to antigen-bearing cancer cells. While lack of immunogenicity intuitively explains the immune silent phenotype, immune exclusion is perplexing. The presence of T cells at the periphery suggests that chemo-attraction recruits them and an immunogenic stimulus promotes their persistence. However, what stops the T cells from infiltrating the tumors' nests and reaching the germinal center (GC)? Possibly, a concentric gradient of increased chemo-repulsion or decreased chemo-attraction demarcates an abrupt "do not trespass" warning. Various hypotheses suggest physical or functional barriers but no definitive consensus exists over the weight that each plays in human cancers. On one hand, it could be hypothesized that the intrinsic biology of cancer cells may degenerate from a "cancer stem cell" (CSC)-like phenotype in the GC toward a progressively more immunogenic phenotype prone to immunogenic cell death (ICD) at the periphery. On the other hand, the intrinsic biology of the cancer cells may not change but it is the disorderly architecture of the tumor microenvironment (TME) that alters in a centripetal direction cancer cell metabolism, both directly and indirectly, the function of surrounding stromal cells. In this chapter, we examine whether the paradoxical exclusion of T cells from tumors may serve as a model to understand the requirements for tumor immune infiltration and, correspondingly, we put forth strategies to restore the dialog between immune cells and cancer to enhance the effectiveness of immune oncology (IO) approaches.

BMP9 mediates the anticancer activity of evodiamine through HIF‑1α/p53 in human colon cancer cells

Colon cancer is one of the most common malignancies. Although there has been great development in treatment regimens over the last few decades, its prognosis remains poor. There is still a clinical need to find new drugs for colon cancer. Evodiamine (Evo) is a quinolone alkaloid extracted from the traditional herbal medicine plant Evodia rutaecarpa. In the present study, CCK-8, flow cytometry, reverse transcription quantitative polymerase chain reaction, western blot analysis and a xenograft tumor model were used to evaluate the anti-cancer activity of Evo in human colon cancer cells and determine the possible mechanism underlying this process. It was revealed that Evo exhibited prominent anti-proliferation and apoptosis-inducing effects in HCT116 cells. Bone morphogenetic protein 9 (BMP9) was notably upregulated by Evo in HCT116 cells. Exogenous BMP9 potentiated the anti-cancer activity of Evo, and BMP9 silencing reduced this effect. In addition, HIF-1α was also upregulated by Evo. The anticancer activity of Evo was enhanced by HIF-1α, but was reduced by HIF-1α silencing. BMP9 potentiated the effect of Evo on the upregulation of HIF-1α, and enhanced the antitumor effect of Evo in colon cancer, which was clearly reduced by HIF-1α silencing. In HCT116 cells, Evo increased the phosphorylation of p53, which was enhanced by BMP9 but reduced by BMP9 silencing. Furthermore, the effect of Evo on p53 was potentiated by HIF-1α and reduced by HIF-1α silencing. The present findings therefore strongly indicated that the anticancer activity of Evo may be partly mediated by BMP9 upregulation, which can activate p53 through upregulation of HIF-1α, at least in human colon cancer.

MSC-secreted TGF-β regulates lipopolysaccharide-stimulated macrophage M2-like polarization via the Akt/FoxO1 pathway

BACKGROUND

An uncontrolled inflammatory response is a critical pathophysiological feature of sepsis. Mesenchymal stem cells (MSCs) induce macrophage phenotype polarization and reduce inflammation in sepsis. MSC-secreted transforming growth factor beta (TGF-β) participated in the immune modulatory function of MSCs. However, the underlying mechanism of MSC-secreted TGF-β was not fully elucidated in regulation macrophage M2-like polarization.

METHODS

The paracrine effects of MSCs on macrophage polarization were studied using a co-culture protocol with LPS-stimulated RAW264.7 cells/mouse peritoneal macrophages and MSCs. The effect of TGF-β in the co-culture system was blocked by the TGF-β receptor inhibitor. To determine the role of MSC-secreted TGF-β, we used recombinant TGF-β to culture with LPS-stimulated RAW264.7 cells. In addition, we employed antibody microarray analysis to determine the mechanisms of MSC secreted TGF-β on LPS-stimulated RAW264.7 cell/mouse peritoneal macrophage M2-like polarization. Furthermore, we used an Akt inhibitor and a FoxO1 inhibitor to inhibit the Akt/FoxO1 pathway. The nuclear translocation of FoxO1 was detected by Western blot.

RESULTS

MSCs induced LPS-stimulated RAW264.7 cell/mouse peritoneal macrophage polarization towards the M2-like phenotype and significantly reduced pro-inflammatory cytokine levels via paracrine, which was inhibited by TGF-β receptor inhibitor. Furthermore, we found that MSC-secreted TGF-β enhanced the macrophage phagocytic ability. The antibody microarray analysis and Western blot verified that TGF-β treatment activated the Akt/FoxO1 pathway in LPS-stimulated macrophages, TGF-β-induced FoxO1 nuclear translocation and obviously expressed in the cytoplasm, the effects of TGF-β regulatory effects on LPS-stimulated macrophage were inhibited by pre-treatment with Akt inhibitor and FoxO1 inhibitor.

CONCLUSIONS

TGF-β secreted by MSCs could skew LPS-stimulated macrophage polarization towards the M2-like phenotype, reduce inflammatory reactions, and improve the phagocytic ability via the Akt/FoxO1 pathway, providing potential therapeutic strategies for sepsis.

On the Neuroprotective Effects of Naringenin: Pharmacological Targets, Signaling Pathways, Molecular Mechanisms, and Clinical Perspective

As a group of progressive, chronic, and disabling disorders, neurodegenerative diseases (NDs) affect millions of people worldwide, and are on the rise. NDs are known as the gradual loss of neurons; however, their pathophysiological mechanisms have not been precisely revealed. Due to the complex pathophysiological mechanisms behind the neurodegeneration, investigating effective and multi-target treatments has remained a clinical challenge. Besides, appropriate neuroprotective agents are still lacking, which raises the need for new therapeutic agents. In recent years, several reports have introduced naturally-derived compounds as promising alternative treatments for NDs. Among natural entities, flavonoids are multi-target alternatives affecting different pathogenesis mechanisms in neurodegeneration. Naringenin is a natural flavonoid possessing neuroprotective activities. Increasing evidence has attained special attention on the variety of therapeutic targets along with complex signaling pathways for naringenin, which suggest its possible therapeutic applications in several NDs. Here, in this review, the neuroprotective effects of naringenin, as well as its related pharmacological targets, signaling pathways, molecular mechanisms, and clinical perspective, are described. Moreover, the need to develop novel naringenin delivery systems is also discussed to solve its widespread pharmacokinetic limitation.

Characterization of inflammatory factor-induced changes in mesenchymal stem cell exosomes and sequencing analysis of exosomal microRNAs

BACKGROUND

Treatments utilizing stems cells often require stem cells to be exposed to inflammatory environments, but the effects of such environments are unknown.

AIM

To examine the effects of inflammatory cytokines on the morphology and quantity of mesenchymal stem cell exosomes (MSCs-exo) as well as the differential expression of microRNAs (miRNAs) in the exosomes.

METHODS

MSCs were isolated from human umbilical tissue by enzymatic digestion. Exosomes were then collected after a 48-h incubation period in a serum-free medium with one of the following the inflammatory cytokines: None (control), vascular cell adhesion molecule-1 (VCAM-1), tumor necrosis factor (TNF) α, and interleukin (IL) 6. The morphology and quantity of each group of MSC exosomes were observed and measured. The miRNAs in MSCs-exo were sequenced. We compared the sequenced data with the miRBase and other non-coding databases in order to detect differentially expressed miRNAs and explore their target genes and regulatory mechanisms. In vitro tube formation assays and Western blot were performed in endothelial cells which were used to assess the angiogenic potential of MSCs-exo after inflammatory cytokine stimulation.

RESULTS

MSCs-exo were numerous, small, and regularly shaped in the VCAM-1 group. TNFα stimulated MSCs to secrete larger and irregular exosomes. IL6 led to a reduced quantity of MSCs-exo. Compared to the control group, the TNFα and IL6 groups had more downregulated differentially expressed miRNAs, particularly angiogenesis-related miRNAs. The angiogenic potential of MSCs-exo declined after IL6 stimulation.

CONCLUSION

TNFα and IL6 may influence the expression of miRNAs that down-regulate the PI3K-AKT, MAPK, and VEGF signaling pathways; particularly, IL6 significantly down-regulates the PI3K-AKT signaling pathway. Overall, inflammatory cytokines may lead to changes in exosomal miRNAs that abnormally impact cellular components, molecular function, and biological processes.

Prevention of neointimal hyperplasia induced by an endovascular stent via intravenous infusion of mesenchymal stem cells

OBJECTIVE

In-stent restenosis after percutaneous transluminal angioplasty and stenting (PTAS) due to neointimal hyperplasia is a potential cause of clinical complications, including repeated revascularization and ischemic events. Neointimal hyperplasia induced by an inflammatory response to the stent strut may be a possible mechanism of in-stent restenosis. Intravenous infusion of bone marrow-derived mesenchymal stem cells (MSCs) has been reported to show therapeutic efficacy for cerebral stroke, presumably by an antiinflammatory effect. This study aimed to determine whether MSCs can reduce or prevent neointimal hyperplasia induced by an endovascular stent.

METHODS

In this study, two types of bare metal stents were deployed using a porcine (mini-pig) model. One stent was implanted in the common carotid artery (CCA), which is considered quite similar to the human CCA, and the other was inserted in the superficial cervical artery (SCA), which is similar in size to the human middle cerebral artery. Angiographic images, intravascular ultrasound (IVUS) imaging, and microscopic images were used for analysis.

RESULTS

Angiographic images and IVUS studies revealed that intravenous infusion of MSCs immediately after deployment of stents prevented in-stent stenosis of the CCA and SCA. Histological analysis also confirmed that inflammatory responses around the stent struts were reduced in both the stented CCA and SCA in the mini-pig.

CONCLUSIONS

Intravenous infusion of MSCs inhibited the inflammatory reaction to an implanted stent strut, and prevented progressive neointimal hyperplasia in the stented CCA and SCA in a porcine model. Thus, MSC treatment could attenuate the recurrence of cerebral ischemic events after stenting.

IL-1β-Primed Mesenchymal Stromal Cells Improve Epidermal Substitute Engraftment and Wound Healing via Matrix Metalloproteinases and Transforming Growth Factor-β1

Since the 1980s, deep and extensive skin wounds and burns are treated with autologous split-thickness skin grafts, or cultured epidermal autografts, when donor sites are limited. However, the clinical use of cultured epidermal autografts often remains unsatisfactory because of poor engraftment rates, altered wound healing, and reduced skin functionality. In the past few decades, mesenchymal stromal cells (MSCs) have raised much attention because of their anti-inflammatory, protrophic, and pro-remodeling capacities. More specifically, gingival MSCs have been shown to possess enhanced wound healing properties compared with other tissue sources. Growing evidence also indicates that MSC priming could potentiate therapeutic effects in diverse in vitro and in vivo models of skin trauma. In this study, we found that IL-1β-primed gingival MSCs promoted cell migration, dermal-epidermal junction formation, and inflammation reduction in vitro, as well as improved epidermal substitute engraftment in vivo. IL-1β-primed gingival MSCs had different secretory profiles from naive gingival MSCs, characterized by an overexpression of transforming growth factor-β and matrix metalloproteinase (MMP) pathway agonists. Eventually, MMP-1, MMP-9, and transforming growth factor-β1 appeared to be critically involved in IL-1β-primed gingival MSC mechanisms of action.

Mesenchymal Stem Cells for Regenerative Medicine

In recent decades, the biomedical applications of mesenchymal stem cells (MSCs) have attracted increasing attention. MSCs are easily extracted from the bone marrow, fat, and synovium, and differentiate into various cell lineages according to the requirements of specific biomedical applications. As MSCs do not express significant histocompatibility complexes and immune stimulating molecules, they are not detected by immune surveillance and do not lead to graft rejection after transplantation. These properties make them competent biomedical candidates, especially in tissue engineering. We present a brief overview of MSC extraction methods and subsequent potential for differentiation, and a comprehensive overview of their preclinical and clinical applications in regenerative medicine, and discuss future challenges.

2,3,7,8-Tetrachlorodibenzo-p-dioxin-induced aryl hydrocarbon receptor activation enhanced the suppressive function of mesenchymal stem cells against splenocyte proliferation

The immunosuppressive function of mesenchymal stem cells (MSCs) is well known. Aryl hydrocarbon receptor (AhR), a transcription factor of the bHLH/PAS family, is widely expressed in several cells and is involved in various physiological and pathological processes. Previously, we found that the expression of AhR was downregulated in MSCs isolated from mice with neutrophilic asthma and that the activation of AhR enhanced the function of MSCs to alleviate neutrophilic asthma. We hypothesized that AhR activation enhanced MSCs for their immunosuppressive function. We aimed to investigate whether AhR activation can augment the suppressive function of MSCs against splenocyte proliferation. We co-cultured MSCs or AhR-activated MSCs with splenocytes at different ratios. The results showed that AhR activation in MSCs upregulated the expression of inducible nitric oxide (iNOS), which promoted the production of nitric oxide (NO), thus enhancing the inhibitory effect on splenocyte proliferation. The NO donor S-nitroso-N-acetylpenicillamine also inhibited the proliferation of splenocytes, and the iNOS inhibitor N(G)-nitro L-arginine methyl ester and NO scavenger 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide partially reversed the immunosuppressive function. Our study indicates that the AhR activation of MSCs might have an important role in the regulation of splenocyte proliferation and might serve as a potential strategy for treating immune-related diseases.

Long-Lasting Anti-Inflammatory Activity of Human Microfragmented Adipose Tissue

Over the last few years, human microfragmented adipose tissue (MFAT), containing significant levels of mesenchymal stromal cells (MSCs) and obtained from fat lipoaspirate (LP) through a minimal manipulation in a closed system device, has been successfully used in aesthetic medicine as well as in orthopedic and general surgery. Interestingly, in orthopedic diseases, this ready-to-use adipose tissue cell derivative seems to have a prolonged time efficacy even upon a single shot injection into osteoarthritic tissues. Here, we investigated the long-term survival and content of MSCs as well the anti-inflammatory activity of LP and its derived MFAT in vitro, with the aim to better understand a possible in vivo mechanism of action. MFAT and LP specimens from 17 human donors were investigated side by side. During a long-term culture in serum-free medium, we found that the total cell number as well the MSC content in MFAT decreased more slowly if compared to those from LP specimens. The analysis of cytokines and growth factors secreted into the conditioned medium (CM) was similar in MFAT and LP during the first week of culture, but the total amount of cytokines secreted by LP decreased much more rapidly than those produced by MFAT during prolonged culture (up to 28 days). Similarly, the addition of MFAT-CM recovered at early (3-7 days) and late stage (14-28 days) of culture strongly inhibited inflammatory function of U937 monocyte cell line, whereas the anti-inflammatory activity of LP-CM was drastically reduced after only 7 days of culture. We conclude that MFAT is an effective preparation with a long-lasting anti-inflammatory activity probably mediated by a long-term survival of their MSC content that releases a combination of cytokines that affect several mechanisms involved in inflammation processes.

Transforming growth factor-β1-overexpressing mesenchymal stromal cells induced local tolerance in rat renal ischemia/reperfusion injury

BACKGROUND

Regulatory T cells (Tregs) suppress excessive immune responses and play a crucial protective role in acute kidney injury (AKI). The aim of this study was to examine the therapeutic potential of transforming growth factor (TGF)-β1-overexpressing mesenchymal stromal cells (MSCs) in inducing local generation of Tregs in the kidney after ischemia/reperfusion (I/R) injury.

METHODS

MSCs were transduced with a lentiviral vector expressing the TGF-β1 gene; TGF-β1-overexpressing MSCs (designated TGF-β1/MSCs) were then transfused into the I/R-injured kidney via the renal artery.

RESULTS

MSCs genetically modified with TGF-β1 achieved overexpression of TGF-β1. Compared with green fluorescent protein (GFP)/MSCs, TGF-β1/MSCs markedly improved renal function after I/R injury and reduced epithelial apoptosis and subsequent inflammation. The enhanced immunosuppressive and therapeutic abilities of TGF-β1/MSCs were associated with increased generation of induced Tregs and improved intrarenal migration of the injected cells. Futhermore, the mechanism of TGF-β1/MSCs in attenuating renal I/R injury was not through a direct canonical TGF-β1/Smad pathway.

CONCLUSION

TGF-β1/MSCs can induce a local immunosuppressive effect in the I/R-injured kidney. The immunomodulatory activity of TGF-β1-modified MSCs appears to be a gateway to new therapeutic approaches to prevent renal I/R injury.

Mesenchymal stem cell-based therapy for autoimmune diseases: emerging roles of extracellular vesicles

In autoimmune disease body's own immune system knows healthy cells as undesired and foreign cells. Over 80 types of autoimmune diseases have been recognized. Currently, at clinical practice, treatment strategies for autoimmune disorders are based on relieving symptoms and preventing difficulties. In other words, there is no effective and useful therapy up to now. It has been well-known that mesenchymal stem cells (MSCs) possess immunomodulatory effects. This strongly suggests that MSCs might be as a novel modality for treatment of autoimmune diseases. Supporting this notion a few preclinical and clinical studies indicate that MSCs ameliorate autoimmune disorders. Interestingly, it has been found that the beneficial effects of MSCs in autoimmune disorders are not relying only on direct cell-to-cell communication but on their capability to produce a broad range of paracrine factors including growth factors, cytokines and extracellular vehicles (EVs). EVs are multi-signal messengers that play a serious role in intercellular signaling through carrying cargo such as mRNA, miRNA, and proteins. Numerous studies have shown that MSC-derived EVs are able to mimic the effects of the cell of origin on immune cells. In this review, we discuss the current studies dealing with MSC-based therapies in autoimmune diseases and provide a vision and highlight in order to introduce MSC-derived EVs as an alternative and emerging modality for autoimmune disorders.

Evaluation of HLA-G Expression in Multipotent Mesenchymal Stromal Cells Derived from Vitrified Wharton's Jelly Tissue

BACKGROUND

Mesenchymal Stromal Cells (MSCs) from Wharton's Jelly (WJ) tissue express HLA-G, a molecule which exerts several immunological properties. This study aimed at the evaluation of HLA-G expression in MSCs derived from vitrified WJ tissue.

METHODS

WJ tissue samples were isolated from human umbilical cords, vitrified with the use of VS55 solution and stored for 1 year at -196 °C. After 1 year of storage, the WJ tissue was thawed and MSCs were isolated. Then, MSCs were expanded until reaching passage 8, followed by estimation of cell number, cell doubling time (CDT), population doubling (PD) and cell viability. In addition, multilineage differentiation, Colony-Forming Units (CFUs) assay and immunophenotypic analyses were performed. HLA-G expression in MSCs derived from vitrified samples was evaluated by immunohistochemistry, RT-PCR/PCR, mixed lymphocyte reaction (MLR) and immunofluorescence. MSCs derived from non-vitrified WJ tissue were used in order to validate the results obtained from the above methods.

RESULTS

MSCs were successfully obtained from vitrified WJ tissues retaining their morphological and multilineage differentiation properties. Furthermore, MSCs from vitrified WJ tissues successfully expressed HLA-G.

CONCLUSION

The above results indicated the successful expression of HLA-G by MSCs from vitrified WJ tissues, thus making them ideal candidates for immunomodulation.