Hypoxia-induced secretion of IL-10 from adipose-derived mesenchymal stem cell promotes growth and cancer stem cell properties of Burkitt lymphoma

A novel cell source for therapy of knee osteoarthritis using atelocollagen microsphere-adhered adipose-derived stem cells: Impact of synovial fluid exposure on cell activity

Introduction

Administration of adipose-derived stem cells (ADSCs) into the joint cavity has been shown to alleviate the symptoms of knee osteoarthritis (OA) by releasing exosomes and anti-inflammatory cytokines. However, the therapeutic effect of these cells is limited by their rapid disappearance after administration. Thus, it is necessary to prolong cell survival in the joint cavity. This study aimed to investigate the potential application of ADSCs adhered to atelocollagen microspheres (AMSs) for cell therapy of knee OA.

Methods

ADSCs were cultured for 2, 4, and 7 days in AMS suspension or adherent culture dishes. The supernatants were analyzed for IL-10 and exosome secretion via enzyme-linked immunosorbent assay and Nanosight. The effect of AMS was compared with that of adherent-cultured ADSCs (2D-cultured ADSCs) using transcriptome analysis. Moreover, the solubility of AMS and viability of ADSCs were evaluated using synovial fluid (SF) from patients with knee OA.

Results

Compared with 2D-cultured ADSCs, AMS-cultured ADSCs exhibited a significant increase in secretion of exosomes and IL-10, and the expression of several genes involved in extracellular matrix and immune regulation were altered. Furthermore, when AMS-cultured ADSCs were cultured in SF from knee OA patients to mimic the intra-articular environment, the SF dissolved the AMSs and released viable ADSCs. In addition, AMS-cultured ADSCs showed significantly higher long-term cell viability than 2D-cultured ADSCs.

Conclusion

Increased survival of AMS-adhered ADSCs was observed in the intra-articular environment, and AMSs were found to gradually dissipate. These results suggest that AMS-adhered ADSCs are promising source for cell therapy of knee OA.

Cell-Based Therapy and Genome Editing as Emerging Therapeutic Approaches to Treat Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation of the joints. Although much remains unknown about the pathogenesis of RA, there is evidence that impaired immune tolerance and the development of RA are related. And it is precisely the restoration of immune tolerance at the site of the inflammation that is the ultimate goal of the treatment of RA. Over the past few decades, significant progress has been made in the treatment of RA, with higher rates of disease remission and improved long-term outcomes. Unfortunately, despite these successes, the proportion of patients with persistent, difficult-to-treat disease remains high, and the task of improving our understanding of the basic mechanisms of disease development and developing new ways to treat RA remains relevant. This review focuses on describing new treatments for RA, including cell therapies and gene editing technologies that have shown potential in preclinical and early clinical trials. In addition, we discuss the opportunities and limitations associated with the use of these new approaches in the treatment of RA.

Potential Consequences of the Use of Adipose-Derived Stem Cells in the Treatment of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) ranks as the most prevalent of primary liver cancers and stands as the third leading cause of cancer-related deaths. Early-stage HCC can be effectively managed with available treatment modalities ranging from invasive techniques, such as liver resection and thermoablation, to systemic therapies primarily employing tyrosine kinase inhibitors. Unfortunately, these interventions take a significant toll on the body, either through physical trauma or the adverse effects of pharmacotherapy. Consequently, there is an understandable drive to develop novel HCC therapies. Adipose-derived stem cells (ADSCs) are a promising therapeutic tool. Their facile extraction process, coupled with the distinctive immunomodulatory capabilities of their secretome, make them an intriguing subject for investigation in both oncology and regenerative medicine. The factors they produce are both enzymes affecting the extracellular matrix (specifically, metalloproteinases and their inhibitors) as well as cytokines and growth factors affecting cell proliferation and invasiveness. So far, the interactions observed with various cancer cell types have not led to clear conclusions. The evidence shows both inhibitory and stimulatory effects on tumor growth. Notably, these effects appear to be dependent on the tumor type, prompting speculation regarding their potential inhibitory impact on HCC. This review briefly synthesizes findings from preclinical and clinical studies examining the effects of ADSCs on cancers, with a specific focus on HCC, and emphasizes the need for further research.

Identification of hub genes regulating the cell activity and function of adipose-derived stem cells under oxygen-glucose deprivation

While oxygen-glucose deprivation (OGD) has been widely utilized in many cell lines to mimic certain biological changes, it has yet to be validated in mesenchymal stem cells. We performed RNA sequencing on adipose-derived stem cells (ADSCs) under hypoxic and glucose-free conditions after 4 h and 8 h. A total of 335 common differentially expressed genes (DEGs) were identified in the two OGD groups compared with the normal control group, consisting of 292 upregulated and 43 downregulated genes. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses indicated that DEGs are mainly involved in metabolic processes, programmed cell death, and DNA-binding transcription activator activity. Protein‒protein interaction and hub gene analysis revealed various potential hub genes, in which response to oxygen levels, the IL-17-related biological function and the hypoxia-inducible factor 1 signaling pathway have been of vital importance. In summary, changes in transcription factor activity may play pivotal roles in oxygen-glucose deprivation. Through RNA sequencing, we have a deeper understanding of the changes in ADSCs after OGD treatment, providing more precise insight into predicting and regulating the stemness of ADSCs.

The role of hypoxic mesenchymal stem cells in tumor immunity

The emerging evidence has shown that mesenchymal stem cells (MSCs) not only exert a significant role in the occurrence and development of tumors, but also have immunosuppressive potential in tumor immunity. Hypoxia is a sign of solid tumors, but how functions of hypoxic MSCs alter in the tumor microenvironment (TME) remains less well and comprehensively described. Herein, we mostly describe and investigate recent advances in our comprehension of the emerging effects of different tissue derived MSCs in hypoxia condition on tumor progression and development, as well as bidirectional influence between hypoxic MSCs and immune cells of the TME. Furthermore, we also discuss the potential drug-resistant and therapeutic role of hypoxic MSCs. It can be envisaged that novel and profound insights into the functionality of hypoxic MSCs and the underlying mechanisms in tumor and tumor immunity will promote the meaningful and promising treatment strategies against tumor.

Mesenchymal Stem Cell-Based Therapy for Rheumatoid Arthritis

Mesenchymal stem cells (MSCs) have great potential to differentiate into various types of cells, including but not limited to, adipocytes, chondrocytes and osteoblasts. In addition to their progenitor characteristics, MSCs hold unique immunomodulatory properties that provide new opportunities in the treatment of autoimmune diseases, and can serve as a promising tool in stem cell-based therapy. Rheumatoid arthritis (RA) is a chronic systemic autoimmune disorder that deteriorates quality and function of the synovium membrane, resulting in chronic inflammation, pain and progressive cartilage and bone destruction. The mechanism of RA pathogenesis is associated with dysregulation of innate and adaptive immunity. Current conventional treatments by steroid drugs, antirheumatic drugs and biological agents are being applied in clinical practice. However, long-term use of these drugs causes side effects, and some RA patients may acquire resistance to these drugs. In this regard, recently investigated MSC-based therapy is considered as a promising approach in RA treatment. In this study, we review conventional and modern treatment approaches, such as MSC-based therapy through the understanding of the link between MSCs and the innate and adaptive immune systems. Moreover, we discuss recent achievements in preclinical and clinical studies as well as various strategies for the enhancement of MSC immunoregulatory properties.

Stem Cell as Vehicles of Antibody in Treatment of Lymphoma: a Novel and Potential Targeted Therapy

Lymphoma is a heterogeneous malignancy and its incidence is increasing in the past decades all over the world. Although more than half of lymphoma patients achieve complete or partial remission from the standard first-line ABVD or R-CHOP based therapy, patients who fail to respond to these regimens will give rise to relapsed or refractory (R/R) lymphoma and may lead to a worse prognosis. Developing novel agents is important for R/R lymphoma. Based on the homing ability and being genetically modified easily, stem cells are usually used as vehicles in cell-based anti-tumor therapy, which can not only retain their own biological characteristics, but also make anti-tumor agents secrete constantly in tumor environment, to eventually kill the tumor cells more effectively. In this review, we will briefly introduce the properties of antibody therapy carried by stem cells, especially the hopes and hurdles of stem cell-mediated antibody secretion in the treatment of lymphoma.

Hypoxia induces an endometrial cancer stem-like cell phenotype via HIF-dependent demethylation of SOX2 mRNA

Endometrial cancer stem cells (ECSCs) are stem-like cells endowed with self-renewal and differentiation abilities, and these cells are essential for cancer progression in endometrial cancer (EC). As hallmarks of the tumour microenvironment (TME), hypoxia and hypoxia-inducing factors (HIFs) give rise to the dysregulation of tumour stemness genes, such as SOX2. Against this backdrop, we investigated the regulatory mechanisms regulated by HIFs and SOX2 in ECSCs during EC development. Here, ECSCs isolated from EC cell lines and tissues were found to express stemness genes (CD133 and aldehyde dehydrogenase, ALDH1) following the induction of their ECSC expansion. Notably, m⁶A methylation of RNA and HIF-1α/2α-dependent AlkB homologue 5 (ALKBH5) participate in the regulation of HIFs and SOX2 in EC, as confirmed by the observations that mRNA levels of m⁶A demethylases and ALKBH5 significantly increase under hypoxic conditions in ECSCs. Moreover, hypoxia and high ALKBH5 levels restore the stem-like state of differentiated ECSCs and increase the ECSC-like phenotype, whereas the knockdown of HIFs or ALKBH5 significantly reduces their tumour initiation capacity. In addition, our findings validate the role of ALKBH5 in promoting SOX2 transcription via mRNA demethylation, thereby maintaining the stem-like state and tumorigenicity potential of ECSCs. In conclusion, these observations demonstrate a critical role for m⁶A methylation-mediated regulation of the HIF-ALKBH5-SOX2 axis during ECSC expansion in hypoxic TMEs.

Allogeneic adipose-derived stem cells promote ischemic muscle repair by inducing M2 macrophage polarization via the HIF-1α/IL-10 pathway

Adipose-derived mesenchymal stem cells (ASCs) are multipotent stromal cells that possess considerable therapeutic potential for tissue remodeling. However, their protective mechanism in critical limb ischemia has not been fully defined. After the occlusion of blood vessels, hypoxia becomes a prominent feature of the ischemic limb. This study investigated the immunomodulatory effect of ASCs on ischemic muscle repair and explored the specific mechanism. We found that the ability of RAW264.7 cells to migrate was impaired in hypoxia, whereas coculturing with ASCs could enhance the migration capacity. In addition, under hypoxic conditions, the paracrine effect of ASCs was enhanced and ASCs could induce RAW264.7 macrophages toward the anti-inflammatory M2 phenotype. We further demonstrated that ASCs-derived interleukin 10 (IL-10), mediated by hypoxia inducible factor-1α (HIF-1α), played a crucial role in the induction of M2 macrophages by activating the signal transducer and activator of transcription 3 (STAT3)/Arginase (Arg-1) pathway. Our in vivo experiments revealed that transplanted ASCs exhibited an immunomodulatory effect by recruiting macrophages to ischemic muscle and increasing the density of M2 macrophages. The transplantation of ASCs into ischemic limbs induced increased blood flow reperfusion and limb salvage rate, whereas the depletion of tissue macrophages or transplanting HIF-1α-silenced ASCs inhibited the therapeutic effect. These findings elucidated the critical role of macrophages in ASCs-mediated ischemic muscle repair and proved that allogeneic ASCs could exert the protective effect by enhancing the recruitment of macrophages and inducing macrophages toward M2 phenotype through HIF-1α/IL-10 pathway.

Role of Apelin/APJ axis in cancer development and progression

Apelin is an endogenous peptide, which is expressed in a vast board of organs such as the brain, placenta, heart, lungs, kidneys, pancreas, testis, prostate and adipose tissues. The apelin receptor, called angiotensin-like-receptor 1 (APJ), is also expressed in the brain, spleen, placenta, heart, liver, intestine, prostate, thymus, testis, ovary, lungs, kidneys, stomach, and adipose tissue. The apelin/APJ axis is involved in a number of physiological and pathological processes. The apelin expression is increased in various kinds of cancer and the apelin/APJ axis plays a key role in the development of tumors through enhancing angiogenesis, metastasis, cell proliferation and also through the development of cancer stem cells and drug resistance. The apelin also stops the apoptosis of cancer cells. The apelin/APJ axis was considered in this review as an attractive therapeutic target for cancer treatment.

Human adipose-derived mesenchymal stem cells inhibit proliferation and induce apoptosis of human gastric cancer HGC-27 cells

The aim of this study was to explore the effects of human adipose-derived mesenchymal stem cells (ASCs) on the growth of gastric cancer cells in vivo and vitro and its mechanism. ASCs were isolated from abandoned adipose tissues, and the surface markers were identified by flow cytometry. In vitro experiments, HGC-27 cells cultured in ASCs-conditioned medium (CM) were assigned as the experimental group, while HGC-27 cells cultured in normal medium were as the control group. MTT and colony formation assays were performed to detect cell viability and colony formatting ability, respectively. Annexin-V/PI assay, Western blot, and caspase-3 enzyme activity assay were performed to detect cells apoptosis. The isolated ASCs could be differentiated into adipocytes and osteoblasts in vitro. Flow cytometry showed that CD73 and CD105 were positively expressed in HGC-27 cells. Compared with the mice injected HGC-27 cells only, the tumor formation in mice injected both ASCs and HGC-27 cells was significantly smaller (P < 0.05). The colony formation ability in experimental group was 40.09% smaller than control group (P < 0.05) and the cell apoptosis rate in experimental group was higher than the control group (P < 0.05). Furthermore, the expressions of cleaved PARP, cleaved caspase-3 proteins, and caspase-3 enzyme viability in experimental group were significantly higher than those of control group (P < 0.05). In conclusion, ASCs can effectively inhibit the growth of HGC-27 cells by inducing apoptosis.

Autophagy regulates the therapeutic potential of adipose-derived stem cells in LPS-induced pulmonary microvascular barrier damage

Adipose-derived stem cells (ADSCs) have been shown to be beneficial in some pulmonary diseases, and the paracrine effect is the major mechanism underlying ADSC-based therapy. Autophagy plays a crucial role in maintaining stem cell homeostasis and survival. However, the role of autophagy in mediating ADSC paracrine effects has not been thoroughly elucidated. We examined whether ADSCs participate in lipopolysaccharide (LPS)-induced pulmonary microvascular endothelial cell (PMVEC) barrier damage in a paracrine manner and illuminated the role of autophagy in regulating ADSC paracrine effects. PMVECs and ADSCs with or without autophagy inhibition were cocultured without intercellular contact, and the microvascular barrier function was assessed after LPS treatment. ADSC paracrine function was evaluated by detecting essential growth factors for endothelial cells. For in vivo experiments, ADSCs with or without autophagy inhibition were transplanted into LPS-induced lung-injury mice, and lung injury was assessed. ADSCs significantly alleviated LPS-induced microvascular barrier injury. In addition, ADSC paracrine levels of VEGF, FGF, and EGF were induced by LPS treatment, especially in the coculture condition. Inhibiting autophagy weakened the paracrine function and the protective effects of ADSCs on microvascular barrier injury. Moreover, ADSC transplantation alleviated LPS-induced lung injury, and inhibiting autophagy markedly weakened the therapeutic effect of ADSCs on lung injury. Together, these findings show that ADSC paracrine effects play a vital protective role in LPS-induced pulmonary microvascular barrier injury. Autophagy is a positive mediating factor in the paracrine process. These results are helpful for illuminating the role and mechanism of ADSC paracrine effects and developing effective therapies in acute lung injury.

Beyond adiponectin and leptin: adipose tissue-derived mediators of inter-organ communication

The breakthrough discoveries of leptin and adiponectin more than two decades ago led to a widespread recognition of adipose tissue as an endocrine organ. Many more adipose tissue-secreted signaling mediators (adipokines) have been identified since then, and much has been learned about how adipose tissue communicates with other organs of the body to maintain systemic homeostasis. Beyond proteins, additional factors, such as lipids, metabolites, noncoding RNAs, and extracellular vesicles (EVs), released by adipose tissue participate in this process. Here, we review the diverse signaling mediators and mechanisms adipose tissue utilizes to relay information to other organs. We discuss recently identified adipokines (proteins, lipids, and metabolites) and briefly outline the contributions of noncoding RNAs and EVs to the ever-increasing complexities of adipose tissue inter-organ communication. We conclude by reflecting on central aspects of adipokine biology, namely, the contribution of distinct adipose tissue depots and cell types to adipokine secretion, the phenomenon of adipokine resistance, and the capacity of adipose tissue to act both as a source and sink of signaling mediators.

Human bone marrow-derived mesenchymal stem cells promote the growth and drug-resistance of diffuse large B-cell lymphoma by secreting IL-6 and elevating IL-17A levels

Background

The drug-resistance and relapse of diffuse large B-cell lymphoma (DLBCL), which are related to mesenchymal stem cells (MSCs), have become increasingly common. However, the underlying mechanisms remain elusive.

Methods

CCK 8 assay, colony formation assay, and xenograft mouse model were used to investigate the effects of hBMSCs on DLBCL growth. Immunohistochemistry, qRT-PCR, and ELISA were used to study the expressions of IL-6 and IL-17A. Flow cytometry was used to analyze Th17 cells and Treg cells expressions. Western blot analysis, microarray analysis, and bioinformatics analysis were used to analyze the pathways of IL-6 or IL-17A mediated DLBCL growth.

Results

HBMSCs promoted DLBCL growth by secreting IL-6 in vitro and in vivo and simultaneously upregulating IL-17A in vitro. IL-6 and IL-17A synergistically promoted the growth and drug-resistance of DLBCL cells by protecting them from spontaneous or drug-induced apoptosis in vitro. IL-6 or IL-17A activated the JAK2/STAT3 pathway or upregulated cyclin D2 via activation of PI3K/Akt signaling in vitro, respectively.

Conclusions

The present results indicated that hBMSCs might have a “dual effect” on promoting DLBCL progression and drug-resistance by secreting IL-6 and upregulating IL-17A. IL-6, IL-17A, p-STAT3, p-Akt or cyclin D2 may be potential molecular targets for overcoming drug-resistance in patients with relapsed or refractory DLBCL.

Gaseous signaling molecules and their application in resistant cancer treatment: from invisible to visible

Multidrug resistance (MDR) in cancer remains a critical obstacle for efficient chemotherapy. Many MDR reversal agents have been discovered but failed in clinical trials due to severe toxic effects. Gaseous signaling molecules (GSMs), such as oxygen, nitric oxide, hydrogen sulfide and carbon monoxide, play key roles in regulating cell biological function and MDR. Compared with other toxic chemosensitizing agents, GSMs are endogenous and biocompatible molecules with little side effects. Research show that GSM modulators, including pharmaceutical formulations of GSMs (combined with conventional chemotherapeutic drugs) and GSM-donors (small molecules with GSMs releasing property), can overcome or reverse MDR. This review discusses the roles of these four GSMs in modulating MDR, and summarizes GSMs modulators in treating cancers with drug resistance.

Cancer Stem Cells: Emergent Nature of Tumor Emergency

A functional analysis of 167 genes overexpressed in Krebs-2 tumor initiating cells was performed. In the first part of the study, the genes were analyzed for their belonging to one or more of the three groups, which represent the three major phenotypic manifestation of malignancy of cancer cells, namely (1) proliferative self-sufficiency, (2) invasive growth and metastasis, and (3) multiple drug resistance. 96 genes out of 167 were identified as possible contributors to at least one of these fundamental properties. It was also found that substantial part of these genes are also known as genes responsible for formation and/or maintenance of the stemness of normal pluri-/multipotent stem cells. These results suggest that the malignancy is simply the ability to maintain the stem cell specific genes expression profile, and, as a consequence, the stemness itself regardless of the controlling effect of stem niches. In the second part of the study, three stress factors combined into the single concept of "generalized cellular stress," which are assumed to activate the expression of these genes, were defined. In addition, possible mechanisms for such activation were identified. The data obtained suggest the existence of a mechanism for the de novo formation of a pluripotent/stem phenotype in the subpopulation of "committed" tumor cells.

Highly Tumorigenic Diffuse Large B Cell Lymphoma Cells Are Produced by Coculture with Stromal Cells

BACKGROUND/AIMS

Diffuse large B cell lymphoma (DLBCL) is heterogeneous. We aimed to explore how tumor microenvironment promotes lymphoma cell aggressiveness and heterogeneity.

METHODS

We created a coculture system using human DLBCL cells and mouse bone marrow stromal cells. Proliferative capacity, drug resistance, clonogenicity, and tumorigenicity were compared in lymphoma cells from the coculture system and lymphoma cells cultured alone. Expression of Notch signaling associated genes was evaluated using real-time reverse transcriptase PCR and Western blot.

RESULTS

Lymphoma cells in the coculture system differentiated into a suspended cell group and an adherent cell group. They acquired a stronger proliferative capacity and drug resistance than lymphoma cells cultured alone, and differences existed between the adherent cell and suspended cell groups. The suspended cell group acquired the most powerful clonogenic and tumorigenic potential. However, Notch3 was exclusively expressed in the adherent lymphoma cell group and the use of N-[N-(3, 5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester, an inhibitor of Notch pathway, could abolish the emergence of highly aggressive lymphoma cells.

CONCLUSION

Highly tumorigenic lymphoma cells could be generated by coculture with stromal cells, and it was dependent on Notch3 expression in the adjacent lymphoma cells through interaction with stromal cells.

Tumor-associated myeloid cells as guiding forces of cancer cell stemness

Due to their ability to differentiate into various cell types and to support tissue regeneration, stem cells simultaneously became the holy grail of regenerative medicine and the evil obstacle in cancer therapy. Several studies have investigated niche-related conditions that favor stemness properties and increasingly emphasized their association with an inflammatory environment. Tumor-associated macrophages (TAMs) and myeloid-derived suppressor cells (MDSCs) are major orchestrators of cancer-related inflammation, able to dynamically express different polarized inflammatory programs that promote tumor outgrowth, including tumor angiogenesis, immunosuppression, tissue remodeling and metastasis formation. In addition, these myeloid populations support cancer cell stemness, favoring tumor maintenance and progression, as well as resistance to anticancer treatments. Here, we discuss inflammatory circuits and molecules expressed by TAMs and MDSCs as guiding forces of cancer cell stemness.

Targeting Cancer Stem Cells-A Renewed Therapeutic Paradigm

Metastasis is often accompanied by radio- and chemotherapeutic resistance to anticancer treatments and is the major cause of death in cancer patients. Better understanding of how cancer cells circumvent therapeutic insults and how disseminated cancer clones generate life-threatening metastases would therefore be paramount to the development of effective therapeutic approaches for clinical management of malignant disease. Mounting reports over the past two decades have provided evidence for the existence of a minor population of highly malignant cells within liquid and solid tumors, which are capable of self-renewing and of regenerating secondary growths with the heterogeneity of the primary tumors from which they derive. These cells, called tumor-initiating cells or cancer stem cells (CSCs) exhibit increased resistance to standard radio- and chemotherapies and appear to have mechanisms that enable them to evade immune surveillance. CSCs are therefore considered to be responsible for systemic residual disease after cancer therapy, as well as for disease relapse. How CSCs develop, the nature of the interactions they establish with their microenvironment, their phenotypic and functional characteristics, as well as their molecular dependencies have all taken center stage in cancer therapy. Indeed, improved understanding of CSC biology is critical to the development of important CSC-based anti-neoplastic approaches that have the potential to radically improve cancer management. Here, we summarize some of the most pertinent elements regarding CSC development and properties, and highlight some of the clinical modalities in current development as anti-CSC therapeutics.

Culture supernatant of adipose stem cells can ameliorate allergic airway inflammation via recruitment of CD4+CD25+Foxp3 T cells

Background

In a previous study, we demonstrated that intravenous administration of adipose tissue stem cells (ASCs) could significantly reduce allergic symptoms and suppress eosinophilic inflammation.

Methods

To evaluate the secretome of ASCs, we administrated culture supernatant of ASCs (ASC sup, which contains the ASC secretome) and uncultured fresh medium (con sup) into a mouse model of allergic airway inflammation. Subsequently we observed the mice for signs of inflammation and investigated Th1-, Th2-, and T_reg-related cytokine levels as well as recruitment of T_reg cells into the airway.

Results

We found that ASC sup could ameliorate allergic airway inflammation in this model; the value of airway hyperresponsiveness, and the occurrence of inflammatory cell infiltration in the lung, as well as the number of eosinophils, and goblet cells in the lung epithelium were all significantly decreased by ASC sup treatment. In addition, ASC sup treatment significantly decreased the levels of IL-4, IL-5, and IL-13 in the bronchial alveolar lavage fluid and in culture medium of lung-draining lymph node cells of the animal model of acute asthma. We detected numerous CTLA-4 and Foxp3-expressing cells in the lung after ASC sup treatment. ASC sup was found to have a higher concentration of IL-10 and TGF-β compared to con sup.

Conclusions

Stem cells have powerful potential for therapeutic functions in various diseases, but they also have many drawbacks. In this study, we found strong immunosuppressive ability of ASC sup in an allergic airway mouse model. It may be possible to use ASC sup for treatment of many immunological diseases in the near future.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-016-0462-5) contains supplementary material, which is available to authorized users.

Preconditioning of Human Mesenchymal Stem Cells to Enhance Their Regulation of the Immune Response

Mesenchymal stem cells (MSCs) have attracted the attention of researchers and clinicians for their ability to differentiate into a number of cell types, participate in tissue regeneration, and repair the damaged tissues by producing various growth factors and cytokines, as well as their unique immunoprivilege in alloreactive hosts. The immunomodulatory functions of exogenous MSCs have been widely investigated in immune-mediated inflammatory diseases and transplantation research. However, a harsh environment at the site of tissue injury/inflammation with insufficient oxygen supply, abundance of reactive oxygen species, and presence of other harmful molecules that damage the adoptively transferred cells collectively lead to low survival and engraftment of the transferred cells. Preconditioning of MSCs ex vivo by hypoxia, inflammatory stimulus, or other factors/conditions prior to their use in therapy is an adaptive strategy that prepares MSCs to survive in the harsh environment and to enhance their regulatory function of the local immune responses. This review focuses on a number of approaches in preconditioning human MSCs with the goal of augmenting their capacity to regulate both innate and adaptive immune responses.

Preconditioning of Human Mesenchymal Stem Cells to Enhance Their Regulation of the Immune Response

Mesenchymal stem cells (MSCs) have attracted the attention of researchers and clinicians for their ability to differentiate into a number of cell types, participate in tissue regeneration, and repair the damaged tissues by producing various growth factors and cytokines, as well as their unique immunoprivilege in alloreactive hosts. The immunomodulatory functions of exogenous MSCs have been widely investigated in immune-mediated inflammatory diseases and transplantation research. However, a harsh environment at the site of tissue injury/inflammation with insufficient oxygen supply, abundance of reactive oxygen species, and presence of other harmful molecules that damage the adoptively transferred cells collectively lead to low survival and engraftment of the transferred cells. Preconditioning of MSCs ex vivo by hypoxia, inflammatory stimulus, or other factors/conditions prior to their use in therapy is an adaptive strategy that prepares MSCs to survive in the harsh environment and to enhance their regulatory function of the local immune responses. This review focuses on a number of approaches in preconditioning human MSCs with the goal of augmenting their capacity to regulate both innate and adaptive immune responses.

Mass spectrometry analysis of adipose-derived stem cells reveals a significant effect of hypoxia on pathways regulating extracellular matrix

Background

Adipose-derived stem cells (ASCs) are being increasingly recognized for their potential to promote tissue regeneration and wound healing. These effects appear to be partly mediated by paracrine signaling pathways, and are enhanced during hypoxia. Mass spectrometry (MS) is a valuable tool for proteomic profiling of cultured ASCs, which may help to reveal the identity of the factors secreted by the cells under different conditions. However, serum starvation which is essentially required to obtain samples compatible with secretome analysis by MS can have a significant influence on ASCs. Here, we present a novel and optimized culturing approach based on the use of a clinically relevant serum-free formulation, which was used to assess the effects of hypoxia on the ASC proteomic profile.

Methods

Human ASCs from three human donors were expanded in StemPro® MSC SFM XenoFree medium. Cells were cultured for 24 h in serum- and albumin-free supplements in either normoxic (20 %) or hypoxic (1 %) atmospheres, after which the cells and conditioned medium were collected, subfractionated, and analyzed using MS. Prior to analysis, the secreted proteins were further subdivided into a secretome (>30 kDa) and a peptidome (3–30 kDa) fraction.

Results

MS analysis revealed the presence of 342, 98, and 3228 proteins in the normoxic ASC secretome, peptidome, and proteome, respectively. A relatively small fraction of the proteome (9.6 %) was significantly affected by hypoxia, and the most regulated proteins were those involved in extracellular matrix (ECM) synthesis and cell metabolism. No proteins were found to be significantly modulated by hypoxic treatment across all cultures for the secretome and peptidome samples.

Conclusions

This study highlights ECM remodeling as a significant mechanism contributing to the ASC regenerative effect after hypoxic preconditioning, and further underscores considerable inter-individual differences in ASC response to hypoxia. The novel culture paradigm provides a basis for future proteomic studies under conditions that do not induce a stress response, so that the best responders can be accurately identified for prospective therapeutic use.

Data are available via ProteomeXchange with identifier PXD003550.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-016-0310-7) contains supplementary material, which is available to authorized users.