CD73 Expression on Mesenchymal Stem Cells Dictates the Reparative Properties via Its Anti-Inflammatory Activity

Urine-derived stem cells serve as a robust platform for generating native or engineered extracellular vesicles

BACKGROUND

Mesenchymal stromal cell (MSC) therapy holds great potential yet efficacy and safety concerns with cell therapy persist. The beneficial effects of MSCs are often attributed to their secretome that includes extracellular vesicles (EVs). EVs carry biologically active molecules, protected by a lipid bilayer. However, several barriers hinder large-scale MSC EV production. A serum-free culturing approach is preferred for producing clinical-grade MSC-derived EVs but this can affect both yield and purity. Consequently, new strategies have been explored, including genetically engineering MSCs to alter EV compositions to enhance potency, increase circulation time or mediate targeting. However, efficient transfection of MSCs is challenging. Typical sources of MSC include adipose tissue and bone marrow, which both require invasive extraction procedures. Here, we investigate the use of urine-derived stem cells (USCs) as a non-invasive and inexhaustible source of MSCs for EV production.

METHODS

We isolated, expanded, and characterized urine-derived stem cells (USCs) harvested from eight healthy donors at three different time points during the day. We evaluated the number of clones per urination, proliferation capacity and conducted flow cytometry to establish expression of surface markers. EVs were produced in chemically defined media and characterized. PEI/DNA transfection was used to genetically engineer USCs using transposon technology.

RESULTS

There were no differences between time points for clone number, doubling time or viability. USCs showed immunophenotypic characteristics of MSCs, such as expression of CD73, CD90 and CD105, with no difference at the assessed time points, however, male donors had reduced CD73 + cells. Expanded USCs were incubated without growth factors or serum for 72 h without a loss in viability and EVs were isolated. USCs were transfected with high efficiency and after 10 days of selection, pure engineered cell cultures were established.

CONCLUSIONS

Isolation and expansion of MSCs from urine is non-invasive, robust, and without apparent sex-related differences. The sampling time point did not affect any measured markers or USC isolation potential. USCs offer an attractive production platform for EVs, both native and engineered.

Characterization of MSCs expressing islet neogenesis associated protein (INGAP): INGAP secretion and cell survival in vitro and in vivo

Mesenchymal stem/stromal cells (MSCs) are emerging as a new therapy for diabetes. Here we investigate the properties of MSCs engineered to express Islet Neogenesis Associated Protein (INGAP) previously shown to reverse diabetes in animal models and evaluate their potential for anti-diabetic applications in mice. Mouse bone marrow-derived MSCs retrovirally transduced to co-express INGAP, Firefly Luciferase and EGFP (INGAP-MSCs), were characterized in vitro and implanted intraperitoneally (IP) into non-diabetic and diabetic C57BL/6 mice (Streptozotocin model) and tracked by live bioluminescence imaging (BLI). Distribution and survival of IP injected INGAP-MSCs differed between diabetic and non-diabetic mice, with a rapid clearance of cells in the latter, and a stronger retention (up to 4 weeks) in diabetic mice concurring with homing towards the pancreas. Interestingly, INGAP-MSCs inhibited the progression of hyperglycemia starting at day 3 and lasting for the entire 6 weeks of the study. Pursuing greater retention, we investigated the survival of INGAP-MSCs in hydrogel matrices. When mixed with Matrigel™ and injected subcutaneously into non-diabetic mice, INGAP-MSCs remained in the implant up to 16 weeks. In vitro tests in three matrices (Matrigel™, Type I Collagen and VitroGel®-MSC) demonstrated that INGAP-MSCs survive and secrete INGAP, with best results at the density of 1-2 x 106 cells/mL. However, all matrices induced spontaneous adipogenic differentiation of INGAP-MSCs in vitro and in vivo, which requires further investigation of its potential impact on MSC therapeutic properties. In summary, based on their ability to stop the rise in hyperglycemia in STZ-treated mice, INGAP-MSCs are a promising therapeutic tool against diabetes but require further research to improve cell delivery and survival.

Exosomes-based immunotherapy for cancer: Effective components in the naïve and engineered forms

Today, cancer treatment is one of the main challenges for researchers. The main cause of tumor cell formation is mutations that lead to uncontrolled proliferation and inhibition of apoptosis in malignant cells. Tumor cells also create a microenvironment that can suppress the immune system cells' responses through various methods, including producing soluble factors and cell-to-cell communication. After being produced from tumor cells, exosomes can also affect the functions of other cells in this microenvironment. Various studies have shown that exosomes from different sources, including tumor cells and immune cells, can be used to treat cancers due to their characteristics. Since tumor cells are rich sources of various types of tumor peptides, they can induce anti-tumor responses. Immune cells also produce exosomes that mimic the functions of their cells of origin, such that exosomes derived from NK cells and CTLs can directly lead to their apoptosis after merging with tumor cells. However, many researchers have pointed out that naïve exosomes have a limited therapeutic function, and their therapeutic potential can be increased by manipulating and engineering them. There are various methods to modify exosomes and improve their therapeutic potential. In general, these methods are divided into two parts, which include changing the cell of origin of the exosome and encapsulating the exosome to carry different drugs. In this review, we will discuss the studies on the therapeutic use of naive and engineered exosomes and provide an update on new studies in this field.

Analysis of the TID-I and TID-L Splice Variants' Expression Profile under In Vitro Differentiation of Human Mesenchymal Bone Marrow Cells into Osteoblasts

Bone formation is a complex process regulated by a variety of pathways that are not yet fully understood. One of the proteins involved in multiple osteogenic pathways is TID (DNAJA3). The aim of this work was to study the association of TID with osteogenesis. Therefore, the expression profiles of the TID splice variants (TID-L, TID-I) and their protein products were analyzed during the proliferation and differentiation of bone marrow mesenchymal stromal cells (B-MSCs) into osteoblasts. As the reference, the hFOB1.19 cell line was used. The phenotype of B-MSCs was confirmed by the presence of CD73, CD90, and CD105 surface antigens on ~97% of cells. The osteoblast phenotype was confirmed by increased alkaline phosphatase activity, calcium deposition, and expression of ALPL and SPP1. The effect of silencing the TID gene on the expression of ALPL and SPP1 was also investigated. The TID proteins and the expression of TID splice variants were detected. After differentiation, the expression of TID-L and TID-I increased 5-fold and 3.7-fold, respectively, while their silencing resulted in increased expression of SPP1. Three days after transfection, the expression of SPP1 increased 7.6-fold and 5.6-fold in B-MSCs and differentiating cells, respectively. Our preliminary study demonstrated that the expression of TID-L and TID-I changes under differentiation of B-MSCs into osteoblasts and may influence the expression of SPP1. However, for better understanding the functional association of these results with the relevant osteogenic pathways, further studies are needed.

Odontoblasts or odontocytes, expression of stem cells markers and differentiation markers among human adult odontoblasts

Despite that, the odontoblasts of the dental pulp are considered a terminally differentiated type of cell. We were interested in investigating if they express any embryonic, mesenchymal, or neural stem cell markers, along with other differentiation markers they were reported to express previously. Methods: An immunohistochemistry study was performed on wisdom teeth extracted from healthy donors aged between 17 and 19 for dental reasons. Nine markers were tested: c-Myc, SOX2, MCAM, CD73, NCAM1, STRO1, osteocalcin, S100, and Thy1. Results: Odontoblasts expressed the following markers: embryonic stem cell markers SOX2, c-Myc, mesenchymal stem cell marker MCAM, the neural differentiation marker S100, and the osteogenic differentiation marker osteocalcin. Odontoblasts did not express the following markers: mesenchymal stem cell markers CD73, STRO1, Thy1, and neural stem cell marker NCAM1. Conclusion: These findings suggest that odontoblasts' expression of these stem cell markers may enable them to dedifferentiate under certain conditions. Further investigation is needed into whether dental materials could induce such dedifferentiation for functional dentin regeneration.

Therapeutic and immunomodulatory potentials of mesenchymal stromal/stem cells and immune checkpoints related molecules

Mesenchymal stromal/stem cells (MSCs) are used in many studies due to their therapeutic potential, including their differentiative ability and immunomodulatory properties. These cells perform their therapeutic functions by using various mechanisms, such as the production of anti-inflammatory cytokines, growth factors, direct cell-to-cell contact, extracellular vesicles (EVs) production, and mitochondrial transfer. However, mechanisms related to immune checkpoints (ICPs) and their effect on the immunomodulatory ability of MSCs are less discussed. The main function of ICPs is to prevent the initiation of unwanted responses and to regulate the immune system responses to maintain the homeostasis of these responses. ICPs are produced by various types of immune system regulatory cells, and defects in their expression and function may be associated with excessive responses that can ultimately lead to autoimmunity. Also, by expressing different types of ICPs and their ligands (ICPLs), tumor cells prevent the formation and durability of immune responses, which leads to tumors' immune escape. ICPs and ICPLs can be produced by MSCs and affect immune cell responses both through their secretion into the microenvironment or direct cell-to-cell interaction. Pre-treatment of MSCs in inflammatory conditions leads to an increase in their therapeutic potential. In addition to the effect that inflammatory environments have on the production of anti-inflammatory cytokines by MSCs, they can increase the expression of various types of ICPLs. In this review, we discuss different types of ICPLs and ICPs expressed by MSCs and their effect on their immunomodulatory and therapeutic potential.

Trends of regenerative tissue engineering for oral and maxillofacial reconstruction in veterinary medicine

Oral and maxillofacial (OMF) defects are not limited to humans and are often encountered in other species. Reconstructing significant tissue defects requires an excellent strategy for efficient and cost-effective treatment. In this regard, tissue engineering comprising stem cells, scaffolds, and signaling molecules is emerging as an innovative approach to treating OMF defects in veterinary patients. This review presents a comprehensive overview of OMF defects and tissue engineering principles to establish proper treatment and achieve both hard and soft tissue regeneration in veterinary practice. Moreover, bench-to-bedside future opportunities and challenges of tissue engineering usage are also addressed in this literature review.

Engineered bone marrow mesenchymal stem cell-derived exosomes loaded with miR302 through the cardiomyocyte specific peptide can reduce myocardial ischemia and reperfusion (I/R) injury

BACKGROUND

MicroRNA (miRNA)-based therapies have shown great potential in myocardial repair following myocardial infarction (MI). MicroRNA-302 (miR302) has been reported to exert a protective effect on MI. However, miRNAs are easily degraded and ineffective in penetrating cells, which limit their clinical applications. Exosomes, which are small bioactive molecules, have been considered as an ideal vehicle for miRNAs delivery due to their cell penetration, low immunogenicity and excellent stability potential. Herein, we explored cardiomyocyte-targeting exosomes as vehicles for delivery of miR302 into cardiomyocyte to potentially treat MI.

METHODS

To generate an efficient exosomal delivery system that can target cardiomyocytes, we engineered exosomes with cardiomyocyte specific peptide (CMP, WLSEAGPVVTVRALRGTGSW). Afterwards, the engineered exosomes were characterized and identified using transmission electron microscope (TEM) and Nanoparticle Tracking Analysis (NTA). Later on, the miR302 mimics were loaded into the engineered exosomes via electroporation technique. Subsequently, the effect of the engineered exosomes on myocardial ischemia and reperfusion (I/R) injury was evaluated in vitro and in vivo, including MTT, ELISA, real-time quantitative polymerase chain reaction (PCR), western blot, TUNNEL staining, echocardiogram and hematoxylin and eosin (HE) staining.

RESULTS

Results of in vitro experimentation showed that DSPE-PEG-CMP-EXO could be more efficiently internalized by H9C2 cells than unmodified exosomes (blank-exosomes). Importantly, compared with the DSPE-PEG-CMP-EXO group, DSPE-PEG-CMP-miR302-EXO significantly upregulated the expression of miR302, while exosomes loaded with miR302 could enhance proliferation of H9C2 cells. Western blot results showed that the DSPE-PEG-CMP-miR302-EXO significantly increased the protein level of Ki67 and Yap, which suggests that DSPE-PEG-CMP-miR302-EXO enhanced the activity of Yap, the principal downstream effector of Hippo pathway. In vivo, DSPE-PEG-CMP-miR302-EXO improved cardiac function, attenuated myocardial apoptosis and inflammatory response, as well as reduced infarct size significantly.

CONCLUSION

In conclusion, our findings suggest that CMP-engineered exosomes loaded with miR302 was internalized by H9C2 cells, an in vitro model for cardiomyocytes coupled with potential enhancement of the therapeutic effects on myocardial I/R injury.

The protective role of CD73 in periodontitis: preventing hyper-inflammatory fibroblasts and driving osteoclast energy metabolism

Introduction

Periodontitis is an immune-mediated inflammatory disease affecting almost half of the adult population and is the leading cause of tooth loss in the United States. The role of extracellular nucleotide signaling including nucleotide metabolizing enzyme CD73 adds an important layer of interaction of purine mediators capable of orchestrating inflammatory outcomes. CD73 is able to catabolize 5'-adenosine monophosphate into adenosine at the extracellular level, playing a critical role in regulating many processes under physiological and pathological conditions. Here, we explored the role of CD73 in ligature-induced periodontitis in vivo comparing wild-type C57Bl/6J and CD73-deficient mice.

Methods

We assessed gingival levels of inflammatory cytokines in vivo and in murine gingival fibroblasts in vitro, as well as bone loss, and RANKL-induced osteoclastogenesis. We have also analyzed CD73 mRNA in samples derived from patients diagnosed with severe periodontitis.

Results

Our results in mice show that lack of CD73 resulted in increased inflammatory cytokines and chemokines such as IL-1β, IL-17, Cxcl1 and Cxcl2 in diseased gingiva relative to the healthy-controls and in comparison with the wild type. CD73-deficient gingival fibroblasts also manifested a defective healing response with higher MMP-13 levels. CD73-deficient animals also showed increased osteoclastogenesis in vitro with increased mitochondrial metabolism typified by excessive activation of oxidative phosphorylation, increased mitochondrial membrane potential and accumulation of hydrogen peroxide. Micro-CT analysis revealed that lack of CD73 resulted in decreased bone mineral density, decreased trabecular bone volume and thickness as well as decreased bone volume in long bones. CD73 deficiency also resulted in increased alveolar bone loss in experimental periodontitis. Correlative studies of gingival samples from severe (Grade C) periodontitis showed decreased levels of CD73 compared to healthy controls, further supporting the relevance of our murine results.

Conclusion

In conclusion, CD73 appears to play a protective role in the gingival periodontal tissue and bone homeostasis, regulating hyper-inflammatory state of stromal fibroblasts and osteoclast energy metabolism and being an important candidate for future target therapies to prevent or control immune-mediated inflammatory and osteolytic diseases.

Tumor necrosis factor α, and agonist and antagonists of cannabinoid receptor type 1 and type 2 alter the immunophenotype of stem cells from human exfoliated deciduous teeth

OBJECTIVE

To verify the involvement of the endocannabinoid system in the immunomodulatory profile of stem cells from human exfoliated deciduous teeth, in the presence or absence of TNF-α, and agonist and antagonists of CB1 and CB2.

METHODS

Stem cells from human exfoliated deciduous teeth were cultured in the presence or absence of an agonist, anandamide, and two antagonists, AM251 and SR144528, of CB1 and CB2 receptors, with or without TNF-α stimulation. For analysis of immunomodulation, surface molecules linked to immunomodulation, namely human leukocyte antigen-DR isotype (HLA-DR), and programmed death ligands 1 (PD-L1) and 2 (PD-L2) were measured using flow cytometry.

RESULTS

The inhibition of endocannabinoid receptors together with the proinflammatory effect of TNF-α resulted in increased HLA-DR expression in stem cells from human exfoliated deciduous teeth, as well as, in these cells acquiring an anti-inflammatory profile by enhancing the expression of PD-L1 and PD-L2.

CONCLUSION

Stem cells from human exfoliated deciduous teeth respond to the endocannabinoid system and TNF-α by altering key immune response molecules. Inhibition of endocannabinoid receptors and TNF-α led to an increase in HLA-DR, PD-L1, and PD-L2 levels in stem cells from human exfoliated deciduous teeth. This study shows the interaction between mesenchymal stromal cells and the immune and endocannabinoid systems.

Adenosine metabolism by mesenchymal stromal cells isolated from different human tissues

Mesenchymal stromal cells (MSCs) have unique biological properties and play important functions, which make them attractive tools for cell-based therapies. The basic mechanisms of these cells are not fully understood. However, the adenosinergic pathway contributes to the main effects attributed to MSCs. Adenosine is a highly immunosuppressive molecule and exerts a central role in inflammation by neutralizing the proinflammatory ATP influence. This nucleoside is produced by purinergic signaling, an important physiological pathway for MSCs, which involves proliferation, migration, differentiation, and apoptosis. Therefore, in this study, we analyzed the extracellular AMP hydrolysis and consequent adenosine production, as well as the expression of CD73 and adenosine receptors on the cell surface of MSCs isolated from different human tissues: dermis (D-MSCs), adipose tissue (AD-MSCs), and umbilical cord (UC-MSCs). All cells confirmed their multipotent capacity by adipogenic, osteogenic, and chondrogenic differentiation, as well as the expression of cell surface markers including CD44 + , CD105 + , and CD90 + . All MSCs expressed similar levels of CD73 and CD26 without a statistical difference among the different tissues, whereas ADA expression was lower in AD-MSCs. In addition, A1R and A3R mRNA levels were higher in D-MSCs and AD-MSCs, respectively. Enzymatic assay showed that AD-MSCs have the highest hydrolysis rate of AMP, leading to increased amount of adenosine production. Moreover, despite all MSCs completely hydrolyze extracellular AMP generating adenosine, the pattern of nucleosides metabolism was different. Therefore, although MSCs share certain characteristics as the multilineage potential and immunophenotype, they show different adenosinergic profiles according to tissue origin.

Comparative Analysis of Porcine Adipose- and Wharton's Jelly-Derived Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) are promising candidates for tissue regeneration, cell therapy, and cultured meat research owing to their ability to differentiate into various lineages including adipocytes, chondrocytes, and osteocytes. As MSCs display different characteristics depending on the tissue of origin, the appropriate cells need to be selected according to the purpose of the research. However, little is known of the unique properties of MSCs in pigs. In this study, we compared two types of porcine mesenchymal stem cells (MSCs) isolated from the dorsal subcutaneous adipose tissue (adipose-derived stem cells (ADSCs)) and Wharton's jelly of the umbilical cord (Wharton's jelly-derived mesenchymal stem cells (WJ-MSCs)) of 1-day-old piglets. The ADSCs displayed a higher proliferation rate and more efficient differentiation potential into adipogenic and chondrogenic lineages than that of WJ-MSCs; conversely, WJ-MSCs showed superior differentiation capacity towards osteogenic lineages. In early passages, ADSCs displayed higher proliferation rates and mitochondrial energy metabolism (measured based on the oxygen consumption rate) compared with that of WJ-MSCs, although these distinctions diminished in late passages. This study broadens our understanding of porcine MSCs and provides insights into their potential applications in animal clinics and cultured meat science.

Biodegradable, Self-Reinforcing Vascular Grafts for In Situ Tissue Engineering Approaches

Clinically available small-diameter synthetic vascular grafts (SDVGs) have unsatisfactory patency rates due to impaired graft healing. Therefore, autologous implants are still the gold standard for small vessel replacement. Bioresorbable SDVGs may be an alternative, but many polymers have inadequate biomechanical properties that lead to graft failure. To overcome these limitations, a new biodegradable SDVG is developed to ensure safe use until adequate new tissue is formed. SDVGs are electrospun using a polymer blend composed of thermoplastic polyurethane (TPU) and a new self-reinforcing TP(U-urea) (TPUU). Biocompatibility is tested in vitro by cell seeding and hemocompatibility tests. In vivo performance is evaluated in rats over a period for up to six months. Autologous rat aortic implants serve as a control group. Scanning electron microscopy, micro-computed tomography (µCT), histology, and gene expression analyses are applied. TPU/TPUU grafts show significant improvement of biomechanical properties after water incubation and exhibit excellent cyto- and hemocompatibility. All grafts remain patent, and biomechanical properties are sufficient despite wall thinning. No inflammation, aneurysms, intimal hyperplasia, or thrombus formation are observed. Evaluation of graft healing shows similar gene expression profiles of TPU/TPUU and autologous conduits. These new biodegradable, self-reinforcing SDVGs may be promising candidates for clinical use in the future.

Validation of multiparametric panels for bovine mesenchymal stromal cell phenotyping

Bovine mesenchymal stromal cells (MSCs) display important features that render them valuable for cell therapy and tissue engineering strategies, such as self-renewal, multi-lineage differentiation, as well as immunomodulatory properties. These cells are also promising candidates to produce cultured meat. For all these applications, it is imperative to unequivocally identify this cell population. The isolation and in vitro tri-lineage differentiation of bovine MSCs is already described, but data on their immunophenotypic characterization is not yet complete. The currently limited availability of monoclonal antibodies (mAbs) specific for bovine MSC markers strongly hampers this research. Following the minimal criteria defined for human MSCs, bovine MSCs should express CD73, CD90, and CD105 and lack expression of CD14 or CD11b, CD34, CD45, CD79α, or CD19, and MHC-II. Additional surface proteins which have been reported to be expressed include CD29, CD44, and CD106. In this study, we aimed to immunophenotype bovine adipose tissue (AT)-derived MSCs using multi-color flow cytometry. To this end, 13 commercial Abs were screened for recognizing bovine epitopes using the appropriate positive controls. Using flow cytometry and immunofluorescence microscopy, cross-reactivity was confirmed for CD34, CD73, CD79α, and CD90. Unfortunately, none of the evaluated CD105 and CD106 Abs cross-reacted with bovine cells. Subsequently, AT-derived bovine MSCs were characterized using multi-color flow cytometry based on their expression of nine markers. Bovine MSCs clearly expressed CD29 and CD44, and lacked expression of CD14, CD45, CD73, CD79α, and MHCII, while a variable expression was observed for CD34 and CD90. In addition, the mRNA transcription level of different markers was analyzed using reverse transcription quantitative polymerase chain reaction. Using these panels, bovine MSCs can be properly immunophenotyped which allows a better characterization of this heterogenous cell population.

A Novel Benchtop Device for Efficient and Simple Purification of Cytokines, Growth Factors and Stem Cells from Adipose Tissue

Lipoaspirates represent a source of adult stem cells, cytokines, and growth factors of adipocyte origin with immunomodulation and regenerative medicine potential. However, rapid and simple protocols for their purification using self-contained devices that can be deployed at the points of care are lacking. Here, we characterize and benchmark a straightforward mechanical dissociation procedure to collect mesenchymal stem cells (MSCs) and soluble fractions from lipoaspirates. IStemRewind, a benchtop self-contained cell purification device, allowed a one-procedure purification of cells and soluble material from lipoaspirates with minimal manipulation. The recovered cellular fraction contained CD73⁺, CD90⁺, CD105⁺, CD10⁺ and CD13⁺ MSCs. These markers were comparably expressed on MSCs isolated using IstemRewind or classic enzymatic dissociation procedures, apart from CD73⁺ MSCs, which were even more abundant in IStemRewind isolates. IstemRewind-purified MSCs retained viability and differentiation into adipocytes and osteocytes, even after a freezing-thawing cycle. Levels of IL4, IL10, bFGF and VEGF were higher compared to the pro-inflammatory cytokines TNFα, IL1β and IL6 in the IStemRewind-isolated liquid fraction. In sum, IStemRewind can be useful for straightforward, rapid, and efficient isolation of MSCs and immunomodulatory soluble factors from lipoaspirates, opening the possibility to directly isolate and employ them at the point-of-care.

CD73-Adenosinergic Axis Mediates the Protective Effect of Extracellular Vesicles Derived from Mesenchymal Stromal Cells on Ischemic Renal Damage in a Rat Model of Donation after Circulatory Death

We propose a new organ-conditioning strategy based on mesenchymal stromal cell (MSCs)/extracellular vesicle (EVs) delivery during hypothermic perfusion. MSCs/EVs marker CD73 is present on renal proximal tubular cells, and it protects against renal ischemia-reperfusion injury by converting adenosine monophosphate into adenosine (ADO). In this study, after checking if CD73-silenced EVs (EVsi) would impact in vitro tubular-cell proliferation, we perfused kidneys of a rat model of donation after circulatory death, with Belzer solution (BS) alone, BS supplemented with MSCs, EVs, or EVsi. The ADO and ATP levels were measured in the effluents and tissues. Global renal ischemic damage score (GRS), and tubular cell proliferation index (IPT) were evaluated in the tissue. EVsi did not induce cell proliferation in vitro. Ex vivo kidneys perfused with BS or BS + EVsi showed the worst GRS and higher effluent ADO levels than the MSC- and EV-perfused kidneys. In the EV-perfused kidneys, the tissue and effluent ATP levels and IPT were the highest, but not if CD73 was silenced. Tissue ATP content was positively correlated with tissue ADO content and negatively correlated with effluent ADO level in all groups. In conclusion, kidney conditioning with EVs protects against ischemic damage by activating the CD73/ADO system.

IL-6 coaxes cellular dedifferentiation as a pro-regenerative intermediate that contributes to pericardial ADSC-induced cardiac repair

Background

Cellular dedifferentiation is a regenerative prerequisite that warrants cell cycle reentry and appropriate mitotic division during de novo formation of cardiomyocytes. In the light of our previous finding that expression of injury-responsive element, Wilms Tumor factor 1 (WT1), in pericardial adipose stromal cells (ADSC) conferred a compelling reparative activity with concomitant IL-6 upregulation, we then aim to unravel the mechanistic network that governs the process of regenerative dedifferentiation after ADSC-based therapy.

Methods and results

WT1-expressing ADSC (eGFP:WT1) were irreversibly labeled in transgenic mice (WT1-iCre/Gt(ROSA)26Sor-eGFP) primed with myocardial infarction. EGFP:WT1 cells were enzymatically isolated from the pericardial adipose tissue and cytometrically purified (ADSC^gfp+). Bulk RNA-seq revealed upregulation of cardiac-related genes and trophic factors in ADSC^gfp+ subset, of which IL-6 was most abundant as compared to non-WT1 ADSC (ADSC^gfp−). Injection of ADSC^gfp+ subset into the infarcted hearts yielded striking structural repair and functional improvement in comparison to ADSC^gfp− subset. Notably, ADSC^gfp+ injection triggered significant quantity of dedifferentiated cardiomyocytes recognized as round-sharp, marginalization of sarcomeric proteins, expression of molecular signature of non-myogenic genes (Vimentin, RunX1), and proliferative markers (Ki-67, Aurora B and pH3). In the cultured neonatal cardiomyocytes, spontaneous dedifferentiation was accelerated by adding tissue extracts from the ADSC-treated hearts, which was neutralized by IL-6 antibody. Genetical lack of IL-6 in ADSC dampened cardiac dedifferentiation and reparative activity.

Conclusions

Taken collectively, our results revealed a previous unappreciated effect of IL-6 on cardiac dedifferentiation and regeneration. The finding, therefore, fulfills the promise of stem cell therapy and may represent an innovative strategy in the treatment of ischemic heart disease.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02675-1.

Genome-wide methylome pattern predictive network analysis reveal mesenchymal stem cell's propensity to undergo cardiovascular lineage

Mesenchymal stem cells (MSCs) differentiation toward cardiovascular lineage prediction using the global methylome profile will highlight its prospective utility in regenerative medicine. We examined the propensity prediction to cardiovascular lineage using 5-Aza, a well-known cardiac lineage inducer. The customized 180 K microarray was performed and further analysis of global differentially methylated regions by Ingenuity pathway analysis (IPA) in both MSCs and 5-AC-treated MSCs. The cluster enrichment tools sorted differentially enriched genes and further annotated to construct the interactive networks. Prediction analysis revealed pathways pertaining to the cardiovascular lineage found active in the native MSCs, suggesting its higher propensity to undergo cardiac, smooth muscle cell, and endothelial lineages in vitro. Interestingly, gene interaction network also proposed majorly stemness gene network NANOG and KLF6, cardiac-specific transcription factors GATA4, NKX2.5, and TBX5 were upregulated in the native MSCs. Furthermore, the expression of cardiovascular lineage specific markers such as Brachury, CD105, CD90, CD31, KDR and various forms of ACTIN (cardiac, sarcomeric, smooth muscle) were validated in native MSCs using real time PCR and immunostaining and blotting analysis. In 5-AC-treated MSCs, mosaic interactive networks were observed to persuade towards osteogenesis and cardiac lineage, indicating that 5-AC treatment resulted in nonspecific lineage induction in MSCs, while MSCs by default have a higher propensity to undergo cardiovascular lineage.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-021-03058-2.

Polychromatic Flow Cytometric Analysis of Stromal Vascular Fraction from Lipoaspirate and Microfragmented Counterparts Reveals Sex-Related Immunophenotype Differences

Mesenchymal stem/stromal cells or medicinal signaling cells (MSC)-based therapy holds promise as a beneficial strategy for treating knee OA (osteoarthritis), but there is no standardized protocols nor mechanistic understanding. In order to gain a better insight into the human MSC from adipose tissue applied for autologous OA treatment, we performed extensive comparative immunophenotyping of the stromal vascular fraction from lipoaspirate or microfragmented lipoaspirates by polychromatic flow cytometry and investigated the cellular components considered responsible for cartilage regeneration. We found an enrichment of the regenerative cellular niche of the clinically applied microfragmented stromal vascular fraction. Sex-related differences were observed in the MSC marker expression and the ratio of the progenitor cells from fresh lipoaspirate, which, in female patients, contained a higher expression of CD90 on the three progenitor cell types including pericytes, a higher expression of CD105 and CD146 on CD31^highCD34^high endothelial progenitors as well as of CD73 on supra-adventitialadipose stromal cells. Some of these MSC-expression differences were present after microfragmentation and indicated a differential phenotype pattern of the applied MSC mixture in female and male patients. Our results provide a better insight into the heterogeneity of the adipose MSC subpopulations serving as OA therapeutics, with an emphasis on interesting differences between women and men.

ADSC-Based Cell Therapies for Musculoskeletal Disorders: A Review of Recent Clinical Trials

Recently published clinical trials involving the use of adipose-derived stem cells (ADSCs) indicated that approximately one-third of the studies were conducted on musculoskeletal disorders (MSD). MSD refers to a wide range of degenerative conditions of joints, bones, and muscles, and these conditions are the most common causes of chronic disability worldwide, being a major burden to the society. Conventional treatment modalities for MSD are not sufficient to correct the underlying structural abnormalities. Hence, ADSC-based cell therapies are being tested as a form of alternative, yet more effective, therapies in the management of MSDs. Therefore, in this review, MSDs subjected to the ADSC-based therapy were further categorized as arthritis, craniomaxillofacial defects, tendon/ligament related disorders, and spine disorders, and their brief characterization as well as the corresponding conventional therapeutic approaches with possible mechanisms with which ADSCs produce regenerative effects in disease-specific microenvironments were discussed to provide an overview of under which circumstances and on what bases the ADSC-based cell therapy was implemented. Providing an overview of the current status of ADSC-based cell therapy on MSDs can help to develop better and optimized strategies of ADSC-based therapeutics for MSDs as well as help to find novel clinical applications of ADSCs in the near future.

Macrophages at the nexus of mesenchymal stromal cell potency: The emerging role of chemokine cooperativity

Pharmacological depletion of macrophages in vivo with liposomal clodronate renders mice unresponsive to adoptive transfer of mesenchymal stromal cells (MSCs) for affecting outcomes of acute inflammatory pathology. This experimental observation identifies host macrophages as necessary in mediating the salutary anti-inflammatory properties of MSCs as a cellular pharmaceutical. This theory is supported by the observation that transfusion of MSCs leads to the prompt phagocytosis of nearly half of lung entrapped MSCs by lung resident macrophages, triggering an interleukin (IL)-10 suppressive efferocytotic response. In addition, non-phagocytosed MSCs with COX2 competency shape the immune milieu by inducing tissue macrophages to express IL-10. Additional experimental evidence identifies MSC-borne IL-6, IDO and TSG-6 as directly involved in macrophage polarization. Along similar lines of functional convergence, implantation of CCL2⁺ MSCs in the extravascular space where interaction with lung resident perivascular macrophages is not operative, also leads to IL-10 polarization of CCR2⁺ macrophages within acute injured tissue far removed from MSC depot. Intriguingly, MSC-derived CCL2 on its own is not sufficient to polarize macrophages and requires heterodimerization with MSC-borne CXCL12 to trigger macrophage IL-10 polarization via CCR2, but not CXCR4. Such chemokine cooperativity opens a new venue for analysis of MSC potency especially considering the rich chemokine secretome of MSC exposed to inflammatory stimulus. As an aggregate, these data highlight a necessary MSC and host macrophage functional dyad that may inform potency attribute analysis of MSCs-including the chemokine interactome-that may be directly linked to in vivo clinical anti-inflammatory and regenerative response.

CD73 Overexpression in Podocytes: A Novel Marker of Podocyte Injury in Human Kidney Disease

The CD73 pathway is an important anti-inflammatory mechanism in various disease settings. Observations in mouse models suggested that CD73 might have a protective role in kidney damage; however, no direct evidence of its role in human kidney disease has been described to date. Here, we hypothesized that podocyte injury in human kidney diseases alters CD73 expression that may facilitate the diagnosis of podocytopathies. We assessed the expression of CD73 and one of its functionally important targets, the C-C chemokine receptor type 2 (CCR2), in podocytes from kidney biopsies of 39 patients with podocytopathy (including focal segmental glomerulosclerosis (FSGS), minimal change disease (MCD), membranous glomerulonephritis (MGN) and amyloidosis) and a control group. Podocyte CD73 expression in each of the disease groups was significantly increased in comparison to controls (p < 0.001–p < 0.0001). Moreover, there was a marked negative correlation between CD73 and CCR2 expression, as confirmed by immunohistochemistry and immunofluorescence (Pearson r = −0.5068, p = 0.0031; Pearson r = −0.4705, p = 0.0313, respectively), thus suggesting a protective role of CD73 in kidney injury. Finally, we identify CD73 as a novel potential diagnostic marker of human podocytopathies, particularly of MCD that has been notorious for the lack of pathological features recognizable by light microscopy and immunohistochemistry.

The Expression Pattern of Surface Markers in Canine Adipose-Derived Mesenchymal Stem Cells

The influence of cultivation on the expression pattern of canine adipose-derived mesenchymal stem cells (cAD-MSCs) surface markers, contributing to, among others, the promotion of growth, proliferation, differentiation and immunomodulatory mechanisms of an excellent therapeutic, is still unknown. To fill the gap, we investigated CD90, CD44, CD73, CD29, CD271, CD105, CD45 and CD14 patterns of expression at the protein level with flow cytometry and mRNA level using a real-time polymerase chain reaction array. Gentle variations of expression occurred during cultivation, along with increased CD90, CD44 and CD29 expression, low and decreasing CD271 and CD73 expression and a decrease of initially high CD105. As expected, CD45 and CD14 were not expressed by cAD-MSCs. Interestingly, we discovered a significant decrease of CD73 expression, compared to early (P1–P3) to late (P4–P6) passages, although the CD73 gene expression was found to be stable. The percentage of positive cells was found to be higher for all positive markers up to P4. As CD73′s one important feature is a modulation from a pro-inflammatory environment to an anti-inflammatory milieu, the expression of CD73 in our conditions indicate the need to consider the time cells spend in vitro before being transplanted into patients, since it could impact their favourable therapeutical properties.

CD73+ Mesenchymal Stem Cells Ameliorate Myocardial Infarction by Promoting Angiogenesis

With multipotent differentiation potential and paracrine capacity, mesenchymal stem cells (MSCs) have been widely applied in clinical practice for the treatment of ischemic heart disease. MSCs are a heterogeneous population and the specific population of MSCs may exhibit a selective ability for tissue repair. The aim of our research was to adapt the CD73⁺ subgroup of adipose derived MSCs (AD-MSCs) for the therapy of myocardial infarction (MI). In this research, AD-MSCs were isolated from adipose tissue surrounding the groin of mice and CD73⁺ AD-MSCs were sorted using flow cytometry. To investigate the therapeutic effects of CD73⁺ AD-MSCs, 1.2 × 10⁶ CD73⁺ AD-MSCs were transplanted into rat model of MI, and CD73^– AD-MSCs, normal AD-MSCs transplantation served as control. Our results revealed that CD73⁺ AD-MSCs played a more effective role in the acceleration function of cardiac recovery by promoting angiogenesis in a rat model of MI compared with mixed AD-MSCs and CD73^– AD-MSCs. Moreover, with the expression of CD73 in AD-MSCs, the secretion of VEGF, SDF-1α, and HGF factors could be promoted. It also shows differences between CD73⁺ and CD73^– AD-MSCs when the transcription profiles of these two subgroups were compared, especially in VEGF pathway. These findings raise an attractive outlook on CD73⁺ AD-MSCs as a dominant subgroup for treating MI-induced myocardial injury. CD73, a surface marker, can be used as a MSCs cell quality control for the recovery of MI by accelerating angiogenesis.

Prenatal transplantation of human amniotic fluid stem cell could improve clinical outcome of type III spinal muscular atrophy in mice

Spinal muscular atrophy (SMA) is a single gene disorder affecting motor function in uterus. Amniotic fluid is an alternative source of stem cell to ameliorate SMA. Therefore, this study aims to examine the therapeutic potential of Human amniotic fluid stem cell (hAFSC) for SMA. Our SMA model mice were generated by deletion of exon 7 of Smn gene and knock-in of human SMN2. A total of 16 SMA model mice were injected with 1 × 10⁵ hAFSC in uterus, and the other 16 mice served as the negative control. Motor function was analyzed by three behavioral tests. Engraftment of hAFSC in organs were assessed by flow cytometry and RNA scope. Frequency of myocytes, neurons and innervated receptors were estimated by staining. With hAFSC transplantation, 15 fetuses survived (93.75% survival) and showed better performance in all motor function tests. Higher engraftment frequency were observed in muscle and liver. Besides, the muscle with hAFSC transplantation expressed much laminin α and PAX-7. Significantly higher frequency of myocytes, neurons and innervated receptors were observed. In our study, hAFSC engrafted on neuromuscular organs and improved cellular and behavioral outcomes of SMA model mice. This fetal therapy could preserve the time window and treat in the uterus.

The adenosinergic pathway in mesenchymal stem cell fate and functions

Mesenchymal stem cells (MSCs) play an important role in tissue homeostasis and damage repair through their ability to differentiate into cells of different tissues, trophic support, and immunomodulation. These properties made them attractive for clinical applications in regenerative medicine, immune disorders, and cell transplantation. However, despite multiple preclinical and clinical studies demonstrating beneficial effects of MSCs, their native identity and mechanisms of action remain inconclusive. Since its discovery, the CD73/ecto-5'-nucleotidase is known as a classic marker for MSCs, but its role goes far beyond a phenotypic characterization antigen. CD73 contributes to adenosine production, therefore, is an essential component of purinergic signaling, a pathway composed of different nucleotides and nucleosides, which concentrations are finely regulated by the ectoenzymes and receptors. Thus, purinergic signaling controls pathophysiological functions such as proliferation, migration, cell fate, and immune responses. Despite the remarkable progress already achieved in considering adenosinergic pathway as a therapeutic target in different pathologies, its role is not fully explored in the context of the therapeutic functions of MSCs. Therefore, in this review, we provide an overview of the role of CD73 and adenosine-mediated signaling in the functions ascribed to MSCs, such as homing and proliferation, cell differentiation, and immunomodulation. Additionally, we will discuss the pathophysiological role of MSCs, via CD73 and adenosine, in different diseases, as well as in tumor development and progression. A better understanding of the adenosinergic pathway in the regulation of MSCs functions will help to provide improved therapeutic strategies applicable in regenerative medicine.

Mesenchymal Stromal Cell-Based Therapies as Promising Treatments for Muscle Regeneration After Snakebite Envenoming

Snakebite envenoming is a global neglected disease with an incidence of up to 2.7 million new cases every year. Although antivenoms are so-far the most effective treatment to reverse the acute systemic effects induced by snakebite envenoming, they have a limited therapeutic potential, being unable to completely neutralize the local venom effects. Local damage, such as dermonecrosis and myonecrosis, can lead to permanent sequelae with physical, social, and psychological implications. The strong inflammatory process induced by snake venoms is associated with poor tissue regeneration, in particular the lack of or reduced skeletal muscle regeneration. Mesenchymal stromal cells (MSCs)-based therapies have shown both anti-inflammatory and pro-regenerative properties. We postulate that using allogeneic MSCs or their cell-free products can induce skeletal muscle regeneration in snakebite victims, improving all the three steps of the skeletal muscle regeneration process, mainly by anti-inflammatory activity, paracrine effects, neovascularization induction, and inhibition of tissue damage, instrumental for microenvironment remodeling and regeneration. Since snakebite envenoming occurs mainly in areas with poor healthcare, we enlist the principles and potential of MSCs-based therapies and discuss regulatory issues, good manufacturing practices, transportation, storage, and related-procedures that could allow the administration of these therapies, looking forward to a safe and cost-effective treatment for a so far unsolved and neglected health problem.

Characterization of the structure, vascularity, and stem/progenitor cell populations in porcine Achilles tendon (PAT)

This study aimed to characterize porcine Achilles tendon (PAT) in terms of its structural components, vascularity, and resident tendon cells. We found that PAT is composed of a paratenon sheath, a core of fascicles, and an endotenon/interfascicular matrix (IFM) that encases the fascicle bundles. We analyzed each of these three tendon components structurally using tissue sections and by isolating cells from each component and analyzing in vitro. Many blood vessel-like tissues were present in the paratenon and IFM but not in fascicles, and the vessels in the paratenon and IFM appeared to be inter-connected. Cells isolated from the paratenon and IFM displayed characteristics of vascular stem/progenitor cells expressing the markers CD105, CD31, with α-smooth muscle actin (α-SMA) localized surrounding blood vessels. The isolated cells from paratenon and IFM also harbored abundant stem/progenitor cells as evidenced by their ability to form colonies and express stem cell markers including CD73 and CD146. Furthermore, we demonstrate that both paratenon and IFM-isolated cells were capable of undergoing multi-differentiation. In addition, both paratenon and IFM cells expressed elastin, osteocalcin, tubulin polymerization promoting protein (TPPP), and collagen IV, whereas fascicle cells expressed none of these markers, except collagen I. The neurotransmitter substance P (SP) was also found in the paratenon and IFM-localized surrounding blood vessels. The findings of this study will help us to better understand the vascular and cellular mechanisms of tendon homeostasis, injury, healing, and regeneration.

TNFR2 Is a Crucial Hub Controlling Mesenchymal Stem Cell Biological and Functional Properties

Mesenchymal stem cells (MSCs) have drawn lots of attention as gold standard stem cells in fundamental and clinical researches during the last 20 years. Due to their tissue and vascular repair capacities, MSCs have been used to treat a variety of degenerative disorders. Moreover, MSCs are able to modulate immune cells’ functions, particularly T cells while inducing regulatory T cells (iTregs). MSCs are very sensitive to inflammatory signals. Their biological functions could remarkably vary after exposure to different pro-inflammatory cytokines, notably TNFα. In this article, we have explored the importance of TNFR2 expression in a series of MSCs’ biological and functional properties. Thus, MSCs from wild-type (WT) and TNFR2 knockout (TNFR2 KO) mice were isolated and underwent several ex vivo experiments to investigate the biological significance of TNFR2 molecule in MSC main functions. Hampering in TNFR2 signaling resulted in reduced MSC colony-forming units and proliferation rate and diminished the expression of all MSC characteristic markers such as stem cell antigen-1 (Sca1), CD90, CD105, CD44, and CD73. TNFR2 KO-MSCs produced more pro-inflammatory cytokines like TNFα, IFNγ, and IL-6 and less anti-inflammatory mediators such as IL-10, TGFβ, and NO and induced Tregs with less suppressive effect. Furthermore, the TNFR2 blockade remarkably decreased MSC regenerative functions such as wound healing, complex tube formation, and endothelial pro-angiogenic support. Therefore, our results reveal the TNFα–TNFR2 axis as a crucial regulator of MSC immunological and regenerative functions.

Recent Advances in GPCR-Regulated Leukocyte Responses during Acute Cardiac Injury

Following acute cardiac injury such as myocardial infarction (MI), the controlled activation and recruitment of various leukocytes to the site of tissue damage significantly impacts chronic changes to cardiac structure and function, and ultimately host survival. While recent research has focused primarily on how leukocytes respond to injury, understanding how to effectively modulate their responsiveness to dampen maladaptive inflammation and promote repair processes is not yet fully understood. The complex spatio-temporal migration and activation of leukocytes are largely controlled by various chemokines and their cognate receptors, belonging to the G protein-coupled receptor (GPCR) family. Beyond chemokine receptors, leukocytes express a host of additional GPCRs that have recently been shown to regulate their responsiveness to cardiac injury. In this minireview, we will briefly discuss the impact of chemokine receptors on leukocyte behaviour, with subsequent focus on the most recent advancements in understanding the impact and therapeutic potential of other GPCR classes on leukocyte responses after acute cardiac injury.

Improving the immunosuppressive potential of articular chondroprogenitors in a three-dimensional culture setting

Cartilage repair in osteoarthritic patients remains a challenge. Identifying resident or donor stem/progenitor cell populations is crucial for augmenting the low intrinsic repair potential of hyaline cartilage. Furthermore, mediating the interaction between these cells and the local immunogenic environment is thought to be critical for long term repair and regeneration. In this study we propose articular cartilage progenitor/stem cells (CPSC) as a valid alternative to bone marrow-derived mesenchymal stem cells (BMMSC) for cartilage repair strategies after trauma. Similar to BMMSC, CPSC isolated from osteoarthritic patients express stem cell markers and have chondrogenic, osteogenic, and adipogenic differentiation ability. In an in vitro 2D setting, CPSC show higher expression of SPP1 and LEP, markers of osteogenic and adipogenic differentiation, respectively. CPSC also display a higher commitment toward chondrogenesis as demonstrated by a higher expression of ACAN. BMMSC and CPSC were cultured in vitro using a previously established collagen-chondroitin sulfate 3D scaffold. The scaffold mimics the cartilage niche, allowing both cell populations to maintain their stem cell features and improve their immunosuppressive potential, demonstrated by the inhibition of activated PBMC proliferation in a co-culture setting. As a result, this study suggests articular cartilage derived-CPSC can be used as a novel tool for cellular and acellular regenerative medicine approaches for osteoarthritis (OA). In addition, the benefit of utilizing a biomimetic acellular scaffold as an advanced 3D culture system to more accurately mimic the physiological environment is demonstrated.

Mesenchymal Stromal Cell Immunology for Efficient and Safe Treatment of Osteoarthritis

Mesenchymal stem cell (MSC) therapy represents a promising approach for the treatment of osteoarthritis (OA). MSCs can be readily isolated from multiple sources and expanded ex vivo for possible clinical application. They possess a unique immunological profile and regulatory machinery that underline their therapeutic effects. They also have the capacity to sense the changes within the tissue environment to display the adequate response. Indeed, there is a close interaction between MSCs and the host cells. Accordingly, MSCs demonstrate encouraging results for a variety of diseases including OA. However, their effectiveness needs to be improved. In this review, we selected to discuss the importance of the immunological features of MSCs, including the type of transplantation and the immune and blood compatibility. It is important to consider MSC immune evasive rather than immune privileged. We also highlighted some of the actions/mechanisms that are displayed during tissue healing including the response of MSCs to injury signals, their interaction with the immune system, and the impact of their lifespan. Finally, we briefly summarized the results of clinical studies reporting on the application of MSCs for the treatment of OA. The research field of MSCs is inspiring and innovative but requires more knowledge about the immunobiological properties of these cells. A better understanding of these features will be key for developing a safe and efficient medicinal product for clinical use in OA.

Characterization of zika virus infection of human fetal cardiac mesenchymal stromal cells

Zika virus (ZIKV) is a single-stranded RNA virus belonging to the family Flaviviridae. ZIKV predominantly enters cells using the TAM-family protein tyrosine kinase receptor AXL, which is expressed on a range of cell types, including neural progenitor cells, keratinocytes, dendritic cells, and osteoblasts. ZIKV infections have been associated with fetal brain damage, which prompted the World Health Organization to declare a public health emergency in 2016. ZIKV infection has also been linked to birth defects in other organs. Several studies have reported congenital heart defects (CHD) in ZIKV infected infants and cardiovascular complications in adults infected with ZIKV. To develop a better understanding of potential causes for these pathologies at a cellular level, we characterized ZIKV infection of human fetal cardiac mesenchymal stromal cells (fcMSCs), a cell type that is known to contribute to both embryological development as well as adult cardiac physiology. Total RNA, supernatants, and/or cells were collected at various time points post-infection to evaluate ZIKV replication, cell death, and antiviral responses. We found that ZIKV productively infected fcMSCs with peak (~70%) viral mRNA detected at 48 h. Use of an antibody blocking the AXL receptor decreased ZIKV infection (by ~50%), indicating that the receptor is responsible to a large extent for viral entry into the cell. ZIKV also altered protein expression of several mesenchymal cell markers, which suggests that ZIKV could affect fcMSCs’ differentiation process. Gene expression analysis of fcMSCs exposed to ZIKV at 6, 12, and 24 h post-infection revealed up-regulation of genes/pathways associated with interferon-stimulated antiviral responses. Stimulation of TLR3 (using poly I:C) or TLR7 (using Imiquimod) prior to ZIKV infection suppressed viral replication in a dose-dependent manner. Overall, fcMSCs can be a target for ZIKV infection, potentially resulting in CHD during embryological development and/or cardiovascular issues in ZIKV infected adults.

Prospective isolation of human fibroadipogenic progenitors with CD73

Skeletal muscle relies on coordination between myogenic and non-myogenic interstitial cells for homeostasis and for regeneration and response to injury. Fibroadipogenic progenitors (FAPs) have recently been recognized as key modulators of signaling to promote myogenesis following injury. FAPs are also responsible for the fibrosis and fatty replacement of muscle tissue seen in many diseased states. While extensive use of surface markers to purify FAPs has been undertaken in the mouse system, in particular PDGFRA, markers for human FAPs are less well understood. Here, we show that CD73 can be used as a single positive marker to purify FAPs from the lineage-negative (CD45-neg, CD31-neg) fraction of skeletal muscle mononuclear cells. Although CD73 was previously found to be expressed in cultured myogenic cells, we find that this marker is only acquired upon culture and that the CD73+ fraction of human skeletal muscle has no myogenic activity. We show that Lin-neg CD73+ cells from human muscle undergo fat differentiation as well as fibrogenesis when exposed to appropriate activating signals in vitro. This simple single positive marker approach effectively enables isolation of human FAPs from fresh human skeletal muscle biopsies.

Human pluripotent stem cell-derived cardiac stromal cells and their applications in regenerative medicine

Coronary heart disease is one of the leading causes of death in the United States. Recent advances in stem cell biology have led to the development and engineering of human pluripotent stem cell (hPSC)-derived cardiac cells and tissues for application in cellular therapy and cardiotoxicity studies. Initial studies in this area have largely focused on improving differentiation efficiency and maturation states of cardiomyocytes. However, other cell types in the heart, including endothelial and stromal cells, play crucial roles in cardiac development, injury response, and cardiomyocyte function. This review discusses recent advances in differentiation of hPSCs to cardiac stromal cells, identification and classification of cardiac stromal cell types, and application of hPSC-derived cardiac stromal cells and tissues containing these cells in regenerative and drug development applications.

The TGF-β profibrotic cascade targets ecto-5'-nucleotidase gene in proximal tubule epithelial cells and is a traceable marker of progressive diabetic kidney disease

Progressive diabetic nephropathy (DN) and loss of renal function correlate with kidney fibrosis. Crosstalk between TGF-β and adenosinergic signaling contributes to the phenotypic transition of cells and to renal fibrosis in DN models. We evaluated the role of TGF-β on NT5E gene expression coding for the ecto-5`-nucleotidase CD73, the limiting enzyme in extracellular adenosine production. We showed that high d-glucose may predispose HK-2 cells towards active transcription of the proximal promoter region of the NT5E gene while additional TGF-β results in full activation. The epigenetic landscape of the NT5E gene promoter was modified by concurrent TGF-β with occupancy by the p300 co-activator and the phosphorylated forms of the Smad2/3 complex and RNA Pol II. Transcriptional induction at NT5E in response to TGF-β was earlier compared to the classic responsiveness genes PAI-1 and Fn1. CD73 levels and AMPase activity were concomitantly increased by TGF-β in HK-2 cells. Interestingly, we found increased CD73 content in urinary extracellular vesicles only in diabetic patients with renal repercussions. Further, CD73-mediated AMPase activity was increased in the urinary sediment of DN patients. We conclude that the NT5E gene is a target of the profibrotic TGF-β cascade and is a traceable marker of progressive DN.

CTRP3 induces an intermediate switch of CD14++CD16+ monocyte subset with anti-inflammatory phenotype

Acute myocardial infarction (AMI) evokes a temporally coordinated immune response, in which monocytes are critically involved in the clearance of cell debris; however, excessive inflammation induced by the classical sub-population of monocytes frequently limits the endogenous reparative process. In the present study, the potential of the anti-inflammatory adipokine complement C1q tumor necrosis factor (TNF)-related protein-3 (CTRP3) to induce intermediate switch of monocytes to an anti-inflammatory phenotype was explored. Circulating monocytes were isolated from patients with AMI at various time-points (3–5 h, 3 days and 7 days) and categorized by flow cytometry/immunostaining into three sub-divisions based on the expression of CD14 and CD16 epitopes: Classical (CD14⁺⁺/CD16⁻), non-classical (CD14⁺/CD16⁺⁺) and intermediate populations (CD14⁺⁺/CD16⁺). The phagocytic activity was evaluated by the ingestion of FITC-Zymosan and ¹⁹F-nanoemulsion and the migratory activity using Thin Cert™ Transwell assay. Monocytes were cultured using autologous serum in the presence of CTRP3 (1 µg/ml) for 24 h and the expression of interleukin 6 (IL-6) and TNF-α was quantified by reverse-transcription quantitative PCR. In addition, SB203580, a p38 mitogen-activated protein kinase (MAPK)/ERK inhibitor, was used to examine the downstream pathways of CTRP3. AMI evoked a transient increase in monocyte counts of the classical subset after onset of the ischemic insult, while the non-classical and intermediate subsets persistently expanded (P<0.01). The monocytes from patients at 3 days after AMI displayed enhanced phagocytic and migratory activities in comparison with those from healthy volunteers (P<0.01). Of note, addition of CTRP3 induced an intermediate switch of monocyte subsets and antagonized the enhanced expression of cytokines, particularly IL-6, in monocytes stressed by lipopolysaccharides, likely by blunting the ERK1/2 and P38 MAPK signaling pathway. In conclusion, the present study demonstrated a dynamic fluctuation of monocyte subsets and enhanced phagocytic and migratory activities in patients with AMI. Furthermore, the ‘proof-of-concept’ evidence pinpoints CTRP3 as an alternative candidate to modulate the ‘uncontrolled’ inflammatory response and thus to augment cardiac reparative processes in patients with AMI.