Mechanism of SB431542 in inhibiting mouse embryonic stem cell differentiation

Cloning and Expression Analysis of TGF-β Type I Receptor Gene in Hyriopsis cumingii

The TGF-β signaling pathway plays an important role in wound healing and immune response. In this study, a TGF-β type I receptor (TGF-βRI) homolog was cloned and characterized from freshwater mussel Hyriopsis cumingii. The full-length cDNA of the TGF-β RI gene was 2017 bp, with a 1554 bp open reading frame (ORF), and encoded 517 amino acids. The predictive analysis further identified distinct regions within the TGF-βRI protein: a signal peptide, a membrane outer region, a transmembrane region, and an intracellular region. Real-time quantitative PCR results showed that the TGF-β RI gene was expressed in all tissues of healthy mussels. The transcripts of TGF-β RI in hemocytes and hepatopancreas were significantly up-regulated at different periods after stimulation with Aeromonas hydrophila and peptidoglycan (PGN) (P < 0.05). The mRNA expression of TGF-β RI progressively increased from day 1 to day 10 after trauma (P < 0.05), and it returned to the initial level by day 15. The expression levels of TGF-β , Smad5, MMP1/19, and TIMP1/2, but not Smad3/4, were significantly up-regulated at different time points after trauma. However, the expression levels of TGF-β , MMP1/19, and TIMP2 were decreased after treatment with the inhibitor SB431542. Furthermore, the recombinant TGF-βRI proteins were expressed in vitro and existed in the form of inclusion bodies. Western blotting results showed that TGF-βRI proteins were expressed constitutively in various tissues of mussels, and their expression was up-regulated after trauma, which was consistent with the mRNA expression trend. These results indicate that TGF-β RI is involved in the process of wound repair and immune response.

GVHD targets organoid-forming bile duct stem cells in a TGF-β-dependent manner

ABSTRACT

Graft-versus-host disease (GVHD) is a major life-threatening complication that occurs after allogeneic hematopoietic cell transplantation (HCT). Although adult tissue stem cells have been identified as targets of GVHD in the skin and gut, their role in hepatic GVHD is yet to be clarified. In the current study, we explored the fate of bile duct stem cells (BDSCs), capable of generating liver organoids in vitro, during hepatic GVHD after allogeneic HCT. We observed a significant expansion of biliary epithelial cells (BECs) on injury early after allogeneic HCT. Organoid-forming efficiency from the bile duct was also significantly increased early after allogeneic HCT. Subsequently, the organoid-forming efficiency from bile ducts was markedly decreased in association with the reduction of BECs and the elevation of plasma concentrations of bilirubin, suggesting that GVHD targets BDSCs and impairs the resilience of BECs. The growth of liver organoids in the presence of liver-infiltrating mononuclear cells from allogeneic recipients, but not from syngeneic recipients, was significantly reduced in a transforming growth factor-β (TGF-β)-dependent manner. Administration of SB-431542, an inhibitor of TGF-β signaling, from day 14 to day 28, protected organoid-forming BDSCs against GVHD and mitigated biliary dysfunction after allogeneic HCT, suggesting that BDSCs are a promising therapeutic target for hepatic GVHD.

GQIcombi application to subdue glioma via differentiation therapy

Current therapy protocols fail to cure high-grade gliomas and prevent recurrence. Therefore, novel approaches need to be developed. A re-programing of glioma cell fate is an alternative attractive way to stop tumor growth. The two-step protocol applies the antiproliferative GQ bi-(AID-1-T) and small molecule inducers with BDNF to trigger neural differentiation into terminally differentiated cells, and it is very effective on GB cell cultures. This original approach is a successful example of the "differentiation therapy". To demonstrate a versatility of this approach, in this publication we have extended a palette of cell cultures to gliomas of II, III and IV Grades, and proved an applicability of that version of differential therapy for a variety of tumor cells. We have justified a sequential mode of adding of GQIcombi components to the glioma cells. We have shown a significant retardation of tumor growth after a direct injection of GQIcombi into the tumor in rat brain, model 101/8. Thus, the proposed strategy of influencing on cancer cell growth is applicable to be further translated for therapy use.

Inhibition of miR-143-3p Restores Blood-Testis Barrier Function and Ameliorates Sertoli Cell Senescence

Due to the increasing trend of delayed childbirth, the age-related decline in male reproductive function has become a widely recognized issue. Sertoli cells (SCs) play a vital role in creating the necessary microenvironment for spermatogenesis in the testis. However, the mechanism underlying Sertoli cell aging is still unclear. In this study, senescent Sertoli cells showed a substantial upregulation of miR-143-3p expression. miR-143-3p was found to limit Sertoli cell proliferation, promote cellular senescence, and cause blood-testis barrier (BTB) dysfunction by targeting ubiquitin-conjugating enzyme E2 E3 (UBE2E3). Additionally, the TGF-β receptor inhibitor SB431542 showed potential in alleviating age-related BTB dysfunction, rescuing testicular atrophy, and reversing the reduction in germ cell numbers by negatively regulating miR-143-3p. These findings clarified the regulatory pathways underlying Sertoli cell senescence and suggested a promising therapeutic approach to restore BTB function, alleviate Sertoli cell senescence, and improve reproductive outcomes for individuals facing fertility challenges.

A cocktail of small molecules maintains the stemness and differentiation potential of conjunctival epithelial cells

PURPOSE

The conjunctival epithelial cells cultured with bovine serum or feeder cells were not suitable for clinical application. Therefore, we developed a novel serum-free and feeder cell-free culture system containing only a cocktail of three chemicals (3C) to expand the conjunctival epithelial cells.

METHODS

The cell proliferative ability was evaluated by counting, crystal violet staining and Ki67 immunostaining. Co-staining of K7 and MUC5AC was performed to identify goblet cells. PAS staining was used to assess the ability of cells to synthesis and secrete glycoproteins. In vivo, eye drops containing 3C was administered to verify the role of 3C in the mouse conjunctival injury model. PAS, HE and immunofluorescence staining were performed to show conjunctival epithelial repair.

RESULTS

Compared with other small molecule groups and the serum group, the cells in 3C group showed superior morphology and proliferative ability. Meanwhile, 3C maintained the well-proliferative capacity of cells even after fifth passage. The 3C group also exhibited more K7 and MUC5AC double positive cells, and the PAS staining positive areas were present in both the cytoplasm and extracellular matrix. The cell sheets treated with 3C in air-lifted culture were obviously stratified. In vivo, more goblet cells in the conjunctival epithelium were observed in the 3C group.

CONCLUSION

Overall, our culture system can expand the conjunctival epithelial cells and retain their potential to differentiate into mature goblet cells, which provided a promising source of seed cells for conjunctival reconstruction. Furthermore, this system provides new insights for the clinical treatment of ocular surface diseases.

Inhibition of TGF-β pathway improved the pluripotency of porcine pluripotent stem cells

Porcine pluripotent stem cells had been derived from different culture systems. PeNK6 is a porcine pluripotent stem cell line that we established from an E5.5 embryo in a defined culture system. Signaling pathways related with pluripotency had been assessed in this cell line, and TGF-β signaling pathway-related genes were found upregulated significantly. In this study, we elucidated the role of the TGF-β signaling pathway in PeNK6 through adding small molecule inhibitors, SB431542 (KOSB) or A83-01 (KOA), into the original culture medium (KO) and analyzing the expression and activity of key factors involved in the TGF-β signaling pathway. In KOSB/KOA medium, the morphology of PeNK6 became compact and the nuclear-to-cytoplasm ratio was increased. The expression of the core transcription factor SOX2 was significantly upregulated compared with cell lines in the control KO medium, and the differentiation potential became balanced among three germ layers rather than bias to neuroectoderm/endoderm as the original PeNK6 did. The results indicated that inhibition of TGF-β has positive effects on the porcine pluripotency. Based on these results, we established a pluripotent cell line (PeWKSB) from E5.5 blastocyst by employing TGF-β inhibitors, and the cell line showed improved pluripotency.

ALK-5 Inhibitors for Efficient Derivation of Mesenchymal Stem Cells from Human Embryonic Stem Cells

Objectives: Successful tissue regeneration requires a clinically viable source of mesenchymal stem cells (MSCs). We explored activin receptor-like kinase (ALK)-5 inhibitors to rapidly derive an MSC-like phenotype with high cartilage forming capacity from a xeno-free human embryonic cell line. Methods: Embryonic stem cell (ESC) lines (H9 and HADC100) were treated with the ALK-5 inhibitor SB431542; HADC100 cells were additionally treated with ALK-5 inhibitors SB525334 or GW788388. Cells were then seeded upon human fibronectin in the presence of fibroblast growth factor 2 (FGF2) in a serum-free medium. Flow cytometry was used to assess MSC markers (positive for CD73, CD90, and CD105; negative for CD34 and CD45). Differentiation status was assessed through quantitative polymerase chain reaction. Cartilage forming capacity was determined in high-density pellet cultures, in fibrin gels containing extracellular matrix (fibrin-ECM), and after implantation in ex vivo human osteoarthritic cartilage. Gene expression, histology, and immunostaining were used to assess cartilage phenotype, tissue regeneration, and integration. Results: Exposure to all three ALK-5 inhibitors lead to expression of mesodermal gene markers and differentiation into MSC-like cells (embryonic stem cell-derived mesenchymal stem cells [ES-MSCs]) based on surface marker expression. ES-MSC in pellet cultures or in fibrin-ECM gels expressed high levels of chondrogenic genes: COL2A1, ACAN, and COMP; and low levels of COL1A1 and RUNX2. Cell pellets or fibrin constructs implanted into ex vivo human osteoarthritic cartilage defects produced GAG-rich (safranin O positive) and collagen type II-positive neocartilage tissues that integrated well with native diseased tissue. Conclusions: We developed a protocol for rapid differentiation of xeno-free ESC into MSC-like cells with high cartilage forming capacity with potential for clinical applications. Impact statement Osteoarthritis (OA) is a common disease resulting in significant disability and no approved disease modifying treatment (other than total joint replacement). Embryonic stem cell-derived cell therapy has the potential to benefit patients with cartilage lesions leading to OA and may prevent or delay the need for total joint replacement.

Challenges Facing the Translation of Embryonic Stem Cell Therapy for the Treatment of Cartilage Lesions

Osteoarthritis is a common disease resulting in significant disability without approved disease-modifying treatment (other than total joint replacement). Stem cell-based therapy is being actively explored for the repair of cartilage lesions in the treatment and prevention of osteoarthritis. Embryonic stem cells are a very attractive source as they address many of the limitations inherent in autologous stem cells, such as variability in function and limited expansion. Over the past 20 years, there has been widespread interest in differentiating ESC into mesenchymal stem cells and chondroprogenitors with successful in vitro, ex vivo, and early animal studies. However, to date, none have progressed to clinical trials. In this review, we compare and contrast the various approaches to differentiating ESC; and discuss the benefits and drawbacks of each approach. Approaches relying on spontaneous differentiation are simpler but not as efficient as more targeted approaches. Methods replicating developmental biology are more efficient and reproducible but involve many steps in a complicated process. The small-molecule approach, arguably, combines the advantages of the above two methods because of the relative efficiency, reproducibility, and simplicity. To better understand the reasons for lack of progression to clinical applications, we explore technical, scientific, clinical, and regulatory challenges that remain to be overcome to achieve success in clinical applications.

miRNAs as cell fate determinants of lateral and paraxial mesoderm differentiation from embryonic stem cells

To date, the role of miRNAs on pluripotency and differentiation of ESCs into specific lineages has been studied extensively. However, the specific role of miRNAs during lateral and paraxial mesoderm cell fate decision is still unclear. To address this, we firstly determined miRNA profile of mouse ESCs differentiating towards lateral and paraxial lineages which were detected using Flk1 and PDGFαR antibodies, and of myogenic and hematopoietic differentiation potential of purified paraxial and lateral mesodermal cells within these populations. miRNAs associated with lateral and paraxial mesoderm, and their targets were identified using bioinformatics tools. The targets of the corresponding miRNAs were validated after transfection into mouse ESCs. The roles of the selected miRNAs in lateral, and paraxial mesoderm formation were assessed along with hematopoietic and myogenic differentiation capacity. Among the miRNAs, mmu-miR-126a-3p, mmu-miR-335-5p and mmu-miR-672-5p, upregulated in lateral mesoderm cells, and mmu-miR-10b-5p, mmu-miR-196a-5p and mmu-miR-615-3p, upregulated in paraxial mesoderm cells. While transient co-transfection of mmu-miR-126a-3p, mmu-miR-335-5p and mmu-miR-672-5p increased the number of lateral mesodermal cells, co-transfection of mmu-miR-10b-5p, mmu-miR-196a-5p and mmu-miR-615-3p increased the number of paraxial mesodermal cells. Moreover, differentiation potential of the lateral mesodermal cells into hematopoietic cell lineage increased upon co-transfection of mmu-miR-126a-3p, mmu-miR-335-5p and mmu-miR-672-5p and differentiation potential of the paraxial mesodermal cells into skeletal muscle lineage were increased upon co-transfection of mmu-miR-10b-5p, mmu-miR-196a-5p and mmu-miR-615-3p. In conclusion, we determined the miRNA profile of lateral and paraxial mesodermal cells and co-transfection of miRNAs increased differentiation potential of both lateral and paraxial mesodermal cells transiently.

Role of the Hippo signaling pathway in safflower yellow pigment treatment of paraquat-induced pulmonary fibrosis

OBJECTIVE

To elucidate the molecular mechanisms by which safflower yellow (SY) mediates therapeutic effects in rats with paraquat intoxication-induced pulmonary fibrosis.

METHODS

Rats received combinations of paraquat, SY, and SB431542, a transforming growth factor (TGF)-β1 receptor antagonist. Survival over 28 days was assessed by Kaplan-Meier analysis. Rat tissue and serum samples were assessed by hematoxylin and eosin staining, Masson's Trichrome staining, immunoblotting, quantitative polymerase chain reaction, enzyme-linked immunosorbent assay, and transmission electron microscopy.

RESULTS

Survival rates were higher in SY and SB431542 groups (treatment and paraquat) than in the exposure group (paraquat alone). In the exposure group, serum TGF-β1 levels increased between days 3 and 14; mammalian STE20-like (MST) levels increased between days 3 and 7; TGF-β1 and Smad3 levels increased between days 3 and 14; and Yap and connective tissue growth factor levels increased between days 3 and 28. TGF-β1 levels were lower in SY and SB431542 groups than in the exposure group. Pathology scores were higher in exposure, SY, and SB431542 groups than in the control group throughout the experiment.

CONCLUSIONS

In rats with paraquat intoxication-induced pulmonary fibrosis, Hippo signaling could be activated by the MST-Yap pathway; SY and SB431542 could alleviate pulmonary fibrosis via Hippo signaling.

Continuous Inhibition of Sonic Hedgehog Signaling Leads to Differentiation of Human-Induced Pluripotent Stem Cells into Functional Insulin-Producing β Cells

Human-induced pluripotent stem cell- (iPSC-) derived insulin-producing cells (IPCs) can be used for islet cell transplantation into type 1 diabetic patients and as patient-specific cells for the development of novel antidiabetic drugs. However, a method is needed to generate functional IPCs from iPSCs and simplify the protocol. We compared combinations of small molecules that could induce the differentiation of cells into a definitive endoderm and preferentially into islet precursor cells. When generated using an optimal combination of small molecules, IPCs secreted insulin in response to glucose stimulation. We constructed spheroid IPCs and optimized the culture and maturation conditions. Quantitative PCR revealed that the expression of definitive endoderm-specific markers differed depending on the combination of the small molecules. The small molecule, N-[(3,5-dimethyl-1-phenyl-1H-pyrazol-4-yl)methylene]-4-(phenylmethyl)-1-piperazinamine, induced the differentiation of cells into functional IPCs by inhibiting Sonic hedgehog signaling. Images of the 2D culture showed that IPCs formed spheroids from day 5 and continuously secreted insulin. We developed a simple differentiation method using small molecules that produced functional IPCs that responded to glucose stimulation within a relatively short period. We posit that this method along with further refinement of the differentiation process can be applied to culture IPCs that can be used in clinical trials.

Culture and differentiation of rabbit intestinal organoids and organoid-derived cell monolayers

Organoids emulate many aspects of their parental tissue and are therefore used to study pathogen-host interactions and other complex biological processes. Here, we report a robust protocol for the isolation, maintenance and differentiation of rabbit small intestinal organoids and organoid-derived cell monolayers. Our rabbit intestinal spheroid and monolayer cultures grew most efficiently in L-WRN-conditioned medium that contained Wnt, R-spondin and Noggin, and that had been supplemented with ROCK and TGF-β inhibitors. Organoid and monolayer differentiation was initiated by reducing the concentration of the L-WRN-conditioned medium and by adding ROCK and Notch signalling inhibitors. Immunofluorescence staining and RT-qPCR demonstrated that our organoids contained enterocytes, enteroendocrine cells, goblet cells and Paneth cells. Finally, we infected rabbit organoids with Rabbit calicivirus Australia-1, an enterotropic lagovirus that—like many other caliciviruses—does not grow in conventional cell culture. Despite testing various conditions for inoculation, we did not detect any evidence of virus replication, suggesting either that our organoids do not contain suitable host cell types or that additional co-factors are required for a productive infection of rabbit organoids with Rabbit calicivirus Australia-1.

Hierarchically Releasing Bio-Responsive Nanoparticles for Complete Tumor Microenvironment Modulation via TGF-β Pathway Inhibition and TAF Reduction

The aggressive progression of breast cancer is impacted significantly by the tumor microenvironment (TME). The current chemotherapy normally causes cytotoxicity to tumor cells, while does not effectively modulate the TME. Thus, the chemotherapy effect of breast cancer is usually dissatisfactory. In this study, a kind of hierarchically releasing bio-responsive nanoparticles (R(D)/H(S) NPs), constructed by β-cyclodextrin-grafted heparin and pH-sensitive pseudorotaxane, were investigated to enhance the breast cancer chemotherapeutic efficacy through TME modulation. Doxorubicin (DOX) and transforming growth factor-β (TGF-β) receptor inhibitor (SB431542) loaded onto R(D)/H(S) NPs were released rapidly for the respective response to low pH in endosomes/lysosomes and heparanase (HPSE) in TME. Our results showed that R(D)/H(S) NPs effectively inhibited the formation of tumor-associated fibroblasts (TAFs) and reduced TGF-β and collagen I secretion. Besides, the immunosuppressive microenvironment was effectively reversed into immunogenic, characterized by increased CD8⁺ and CD4⁺ T cell infiltration, which distinctly inhibited breast cancer metastasis. Therefore, R(D)/H(S) NPs remodeled the TME by downregulating TAFs, TGF-β, and collagen I; activating the immune microenvironment; and then amplifying the chemotherapeutic efficacy of DOX.

TGF-β1 mediated Smad signaling pathway and EMT in hepatic fibrosis induced by Nano NiO in vivo and in vitro

Nickel oxide nanoparticles (Nano NiO) bears hepatotoxicity, while whether it leads to liver fibrosis remains unclear. The aim of this study was to establish the Nano NiO-induced hepatic fibrosis model in vivo and investigate the roles of transforming growth factor β1 (TGF-β1) in Smad pathway activation, epithelial-mesenchymal transition (EMT) occurrence, and extracellular matrix (ECM) deposition in vitro. Male Wistar rats were exposed to 0.015, 0.06, and 0.24 mg/kg Nano NiO by intratracheal instilling twice a week for 9 weeks. HepG2 cells were treated with 100 μg/mL Nano NiO and TGF-β1 inhibitor (SB431542) to explore the mechanism of collagen formation. Results of Masson staining as well as the elevated levels of type I collagen (Col-I) and Col-III suggested that Nano NiO resulted in hepatic fibrosis in rats. Furthermore, Nano NiO increased the protein expression of TGF-β1, p-Smad2, p-Smad3, alpha-smooth muscle actin (α-SMA), matrix metalloproteinase9 (MMP9), and tissue inhibitors of metalloproteinase1 (TIMP1), while decreased the protein content of E-cadherin and Smad7 in rat liver and HepG2 cells. Most importantly, Nano NiO-triggered the abnormal expression of the abovementioned proteins were all alleviated by co-treatment with SB431542, implying that TGF-β1-mediated Smad pathway, EMT and MMP9/TIMP1 imbalance were involved in overproduction of collagen in HepG2 cells. In conclusion, these findings indicated that Nano NiO induced hepatic fibrosis via TGF-β1-mediated Smad pathway activation, EMT occurrence, and ECM deposition.

Retinoic Acid Induces Differentiation of Mouse F9 Embryonic Carcinoma Cell by Modulating the miR-485 Targeting of Abhd2

Retinoic acid (RA) plays a key role in pluripotent cell differentiation. In F9 embryonic carcinoma cells, RA can induce differentiation towards somatic lineages via the Ras-extracellular signal-regulated kinase (Ras/Erk) pathway, but the mechanism through which it induces the Erk1/2 phosphorylation is unclear. Here, we show that miR-485 is a positive regulator that targets α/β-hydrolase domain-containing protein 2 (Abhd2), which can result in Erk1/2 phosphorylation and triggers differentiation. RA up-regulates miR-485 and concurrently down-regulates Abhd2. We verified that Abhd2 is targeted by miR-485 and they both can influence the phosphorylation of Erk1/2. In summary, RA can mediate cell differentiation by phosphorylating Erk1/2 via miR-485 and Abhd2.

Reactive Oxygen Species and p38MAPK Have a Role in the Smad2 Linker Region Phosphorylation Induced by TGF-β

BACKGROUND

Transforming growth factor-β (TGF-β) in addition to the C-terminal region can phosphorylate receptor-regulated Smads (R-Smads) in their linker region. The aim of the present study was to evaluate the role of signaling mediators such as NAD(P)H oxidases (reactive oxygen species [ROS] generators), ROS, and ROS-sensitive p38 mitogen-activated protein kinase (p38MAPK) in this signaling pathway in cultured human vascular smooth muscle cells (VSMCs).

METHODS

The present in vitro study was performed on human VSMCs. Proteins were detected by western blotting utilizing an anti-phospho-Smad2 (Ser245/250/255) rabbit polyclonal antibody and a horseradish peroxidase-labeled secondary antibody. Glyceraldehyde-3-phosphate dehydrogenase was used as a loading control. The phospho-Smad2 linker region (pSmad2L) was detected in all the experimental groups: a control group (untreated group), a group treated with TGF-β (2 ng/mL), and a group treated with TGF-β plus different inhibitors. The data were normalized and presented as mean±SEM. The statistical analyses were performed using SPSS, version 16.0, and the nonparametric Kruskal-Wallis test. A P value smaller than 0.05 was considered statistically significant.

RESULTS

The VSMCs treated with TGF-β (2 ng/mL) showed a time-dependent increase in the pSmad2L level. The highest level was observed at 15 minutes (P=0.03). The inhibitors of NAD(P)H oxidases (diphenyleneiodonium and apocynin) (P=0.04), ROS scavenger (N-acetylcysteine) (P=0.04), and p38MAPK inhibitor (SB-202190) (P=0.04) were able to reduce the increased level of the pSmad2L by TGF-β.

CONCLUSION

Our results suggested that NAD(P)H oxidases played an important role in the Smad2L phosphorylation in the human VSMCs. Furthermore, our results confirmed that ROS and p38MAPK were involved in this signaling pathway. Thus, TGF-β via a ROS-dependent mechanism can transmit its signals to the pSmad2L.

miR-24 and miR-122 Negatively Regulate the Transforming Growth Factor-β/Smad Signaling Pathway in Skeletal Muscle Fibrosis

Fibrosis is common after skeletal muscle injury, undermining tissue regeneration and function. The mechanism underlying skeletal muscle fibrosis remains unveiled. Transforming growth factor-β/Smad signaling pathway is supposed to play a pivotal role. However, how microRNAs interact with transforming growth factor-β/Smad-related muscle fibrosis remains unclear. We showed that microRNA (miR)-24-3p and miR-122-5p declined in skeletal muscle fibrosis, which was a consequence of transforming growth factor-β. Upregulating Smad4 suppressed two microRNAs, whereas inhibiting Smad4 elevated microRNAs. Luciferase reporter assay and chromatin immunoprecipitation confirmed that Smad4 directly inhibited two microRNAs. On the other hand, overexpression of these two miRs retarded fibrotic process. We further identified that Smad2 was a direct target of miR-24-3p, whereas miR-122-5p targeted transforming growth factor-β receptor-II. Both targets were important participants in transforming growth factor-β/Smad signaling. Taken together, a positive feedback loop in transforming growth factor-β/Smad4 signaling pathway in skeletal muscle fibrosis was identified. Transforming growth factor-β/Smad axis could be downregulated by microRNAs. This effect, however, was suppressed by Smad4, the downstream of transforming growth factor-β.

Differences in the Activity of Endogenous Bone Morphogenetic Protein Signaling Impact on the Ability of Induced Pluripotent Stem Cells to Differentiate to Corneal Epithelial-Like Cells

Cornea is a clear outermost layer of the eye which enables transmission of light onto the retina. The transparent corneal epithelium is regenerated by limbal stem cells (LSCs), whose loss/dysfunction results in LSCs deficiency (LSCD). Ex vivo expansion of autologous LSCs obtained from patient's healthy eye followed by transplantation onto the LSCs damaged/deficient eye, has provided a successful treatment for unilateral LSCD. However, this is not applicable to patient with total bilateral LSCD, where LSCs are lost/damaged from both eyes. We investigated the potential of human induced pluripotent stem cell (hiPSC) to differentiate into corneal epithelial‐like cells as a source of autologous stem cell treatment for patients with total bilateral LSCD. Our study showed that combined addition of bone morphogenetic protein 4 (BMP4), all trans‐retinoic acid and epidermal growth factor for the first 9 days of differentiation followed by cell‐replating on collagen‐IV‐coated surfaces with a corneal‐specific‐epithelial cell media for an additional 11 days, resulted in step wise differentiation of human embryonic stem cells (hESC) to corneal epithelial progenitors and mature corneal epithelial‐like cells. We observed differences in the ability of hiPSC lines to undergo differentiation to corneal epithelial‐like cells which were dependent on the level of endogenous BMP signaling and could be restored via the activation of this signaling pathway by a specific transforming growth factor β inhibitor (SB431542). Together our data reveal a differential ability of hiPSC lines to generate corneal epithelial cells which is underlined by the activity of endogenous BMP signaling pathway. Stem Cells2018;36:337–348

Pluripotent Stem Cells as a Robust Source of Mesenchymal Stem Cells

Mesenchymal stem cells (MSC) have been extensively studied over the past years for the treatment of different diseases. Most of the ongoing clinical trials currently involve the use of MSC derived from adult tissues. This source may have some limitations, particularly with therapies that may require extensive and repetitive cell dosage. However, nowadays, there is a staggering growth in literature on a new source of MSC. There is now increasing evidence about the mesenchymal differentiation from pluripotent stem cell (PSC). Here, we summarize the current knowledge of pluripotent-derived mesenchymal stem cells (PD-MSC). We present a historical perspective on the subject, and then discuss some critical questions that remain unanswered.

miR‑146b‑5p promotes the neural conversion of pluripotent stem cells by targeting Smad4

Pluripotent stem cells (PSCs) are regarded as potential sources that provide specific neural cells for cell therapy in some nervous system diseases. However, the mechanisms underlying the neural differentiation of PSCs remain largely unknown. MicroRNAs (miRNAs or miRs) are a class of small non-protein-coding RNAs that act as critical regulatory molecules in many cellular processes. In this study, we found that miR-146b-5p expression was markedly increased following the neural induction of mouse embryonic stem cells (ESCs) or induced PSCs (iPSCs). In this study, to further identify the role of miR-146b-5p, we generated stable miR-146b-5p- overexpressing ESC and iPSC cell lines, and induced the differentiation of these cells by the adherent monolayer culture method. In the miR-146b-5p-overexpressing ESC- or iPSC- derived cultures, RT-qPCR analysis revealed that the mRNA expression levels of neuroectoderm markers, such as Sox1, Nestin and Pax6, were markedly increased, and flow cytometric analysis verified that the number of Nestin-positive cells was higher in the miR-146b-5p-overexpressing compared with the control cells. Mechanistically, the miR-146b-5p-overexpressing ESCs or iPSCs exhibited a significant reduction in Oct4 expression, which may be an explanation for these cells having a tendency to differentiate towards the neural lineage. Moreover, we confirmed that miR-146b-5p directly targeted Smad4 and negatively regulated the transforming growth factor (TGF)-β signaling pathway, which contributed to the neural commitment of PSCs. Collectively, our findings uncover the essential role of miR-146b-5p in the neural conversion of PSCs.

CRISPR/Cas9 Targeted Gene Editing and Cellular Engineering in Fanconi Anemia

The ability to rationally target disease-causing mutations has been made possible with programmable nucleases with the CRISPR/Cas9 system representing a facile platform for individualized gene-based medicine. In this study we employed footprint free reprogramming of fibroblasts from a patient with mutations to the Fanconi anemia I (FANCI) gene to generate induced pluripotent stem cells (iPSC). This process was accomplished without gene complementation and the resultant iPSC were able to be gene corrected in a robust manner using the Cas9 nickase. The self-renewing iPSC that were maintained under feeder free conditions were differentiated into cells with characteristics of definitive hematopoiesis. This defined and highly efficient procedure employed small molecule modulation of the hematopoietic differentiation pathway and a vascular induction technique to generate hematopoietic progenitors. In sum, our results demonstrate the ability to induce patient derived FA cells to pluripotency for patient specific therapeutic cell derivation.

Targeting the transforming growth factor-β signaling during pre-implantation development in embryos of cattle, sheep and goats

Recently, application of chemical inhibitors against differentiation signaling pathways has improved establishment of mESCs. In this study, we applied inhibitors of TGF-β (SB431542) and BMP4 (Noggin) from cleavage to blastocyst stage in cattle, goat and sheep embryos. SB significantly decreases blastocyst rate and total cell number (TCN) in sheep blastocysts, whereas only TCN was significantly decreased in cattle blastocysts. In contrast to SB, Noggin significantly improved cattle blastocyst development but decreased TCN. However, Noggin treatment led to a significant increase in TCN in sheep blastocysts. Regarding pluripotency triad (OCT4, NANOG, SOX2) and cell lineage commitment (REX1, CDX2, GATA4), SB led to a significant reduction in SOX2 expression in goat and cattle, while Noggin increased at least one or two of pluripotent markers in these species. Taken together, this data suggests that inhibition of TGF-β by Noggin may be more favorable for derivation of stem cells in farm animals.

Pluripotent Stem Cells from Domesticated Mammals

This review deals with the latest advances in the study of embryonic stem cells (ESC) and induced pluripotent stem cells (iPSC) from domesticated species, with a focus on pigs, cattle, sheep, goats, horses, cats, and dogs. Whereas the derivation of fully pluripotent ESC from these species has proved slow, reprogramming of somatic cells to iPSC has been more straightforward. However, most of these iPSC depend on the continued expression of the introduced transgenes, a major drawback to their utility. The persistent failure in generating ESC and the dependency of iPSC on ectopic genes probably stem from an inability to maintain the stability of the endogenous gene networks necessary to maintain pluripotency. Based on work in humans and rodents, achievement of full pluripotency will likely require fine adjustments in the growth factors and signaling inhibitors provided to the cells. Finally, we discuss the future utility of these cells for biomedical and agricultural purposes.

Advanced glycation end-products accelerate the cardiac aging process through the receptor for advanced glycation end-products/transforming growth factor-β-Smad signaling pathway in cardiac fibroblasts

AIMS

The current study was carried out to evaluate the effect of advanced glycation end-products (AGE) on cardiac aging and to explore its underlying mechanisms.

METHODS

Neonatal rat cardiac fibroblasts were cultured and divided into four groups: control; AGE; AGE + receptor for AGE antibody and AGE + SB431542 (transforming growth factor-β [TGF-β]/Smad signaling pathway inhibitor, 10 μmol/L) group. After being cultured for 48 h, the cells were harvested and the senescence-associated beta-galactosidase expression was analyzed. Then the level of p16, TGF-β, Smad/p-smad and matrix metalloproteinases-2 was evaluated by western blot.

RESULTS

Significantly increased senescence-associated beta-galactosidase activity as well as p16 level was observed in the AGE group. Furthermore, AGE also significantly increased the TGF-β1, p-smad2/3 and metalloproteinases-2 expression in cardiac fibroblasts (all P < 0.01). Meanwhile, either pretreatment with receptor for AGE-Ab or SB431542 significantly inhibited the upregulated cardiac senescence (beta-galactosidase activity and P16) and fibrosis-associated (TGF-β1, p-smad2/3 and metalloproteinases-2) markers induced by AGE.

CONCLUSIONS

Taken together, all these results suggested that AGE are an important factor for cardiac aging and fibrosis, whereas the receptor for AGE and TGF-β/Smad signaling pathway might be involved in the AGE-induced cardiac aging process.

Inhibition of transforming growth factor β signaling promotes epiblast formation in mouse embryos

Early lineage segregation in preimplantation embryos and maintenance of pluripotency in embryonic stem cells (ESCs) are both regulated by specific signaling pathways. Small molecules have been shown to modulate these signaling pathways. We examined the influence of several small molecules and growth factors on second-lineage segregation of the inner cell mass toward hypoblast and epiblast lineage during mouse embryonic preimplantation development. We found that the second-lineage segregation is influenced by activation or inhibition of the transforming growth factor (TGF)β pathway. Inhibition of the TGFβ pathway from the two-cell, four-cell, and morula stages onward up to the blastocyst stage significantly increased the epiblast cell proliferation. The epiblast formed in the embryos in which TGFβ signaling was inhibited was fully functional as demonstrated by the potential of these epiblast cells to give rise to pluripotent ESCs. Conversely, activating the TGFβ pathway reduced epiblast formation. Inhibition of the glycogen synthase kinase (GSK)3 pathway and activation of bone morphogenetic protein 4 signaling reduced the formation of both epiblast and hypoblast cells. Activation of the protein kinase A pathway and of the Janus kinase/signal transducer and activator of transcription 3 pathway did not influence the second-lineage segregation in mouse embryos. The simultaneous inhibition of three pathways--TGFβ, GSK3β, and the fibroblast growth factor (FGF)/extracellular signal-regulated kinases (Erk)--significantly enhanced the proliferation of epiblast cells than that caused by inhibition of either TGFβ pathway alone or by combined inhibition of the GSK3β and FGF/Erk pathways only.

TGFβ signaling promotes matrix assembly during mechanosensitive embryonic salivary gland restoration

Mechanical properties of the microenvironment regulate cell morphology and differentiation within complex organs. However, methods to restore morphogenesis and differentiation in organs in which compliance is suboptimal are poorly understood. We used mechanosensitive mouse salivary gland organ explants grown at different compliance levels together with deoxycholate extraction and immunocytochemistry of the intact, assembled matrices to examine the compliance-dependent assembly and distribution of the extracellular matrix and basement membrane in explants grown at permissive or non-permissive compliance. Extracellular matrix and basement membrane assembly were disrupted in the glands grown at low compliance compared to those grown at high compliance, correlating with defective morphogenesis and decreased myoepithelial cell differentiation. Extracellular matrix and basement membrane assembly as well as myoepithelial differentiation were restored by addition of TGFβ1 and by mechanical rescue, and mechanical rescue was prevented by inhibition of TGFβ signaling during the rescue. We detected a basal accumulation of active integrin β1 in the differentiating myoepithelial cells that formed a continuous peripheral localization around the proacini and in clefts within active sites of morphogenesis in explants that were grown at high compliance. The pattern and levels of integrin β1 activation together with myoepithelial differentiation were interrupted in explants grown at low compliance but were restored upon mechanical rescue or with application of exogenous TGFβ1. These data suggest that therapeutic application of TGFβ1 to tissues disrupted by mechanical signaling should be examined as a method to promote organ remodeling and regeneration.

Inhibition of transforming growth factor β (TGF-β) signaling can substitute for Oct4 protein in reprogramming and maintain pluripotency

Mouse pluripotent stem cells (PSCs), such as ES cells and induced PSCs (iPSCs), are an excellent system to investigate the molecular and cellular mechanisms involved in early embryonic development. The signaling pathways orchestrated by leukemia inhibitor factor/STAT3, Wnt/β-catenin, and FGF/MEK/ERK play key roles in the generation of pluripotency. However, the function of TGF-β signaling in this process remains elusive. Here we show that inhibiting TGF-β signaling with its inhibitor SB431542 can substitute for Oct4 during reprogramming. Moreover, inhibiting TGF-β signaling can sustain the pluripotency of iPSCs and ES cells through modulating FGF/MEK/ERK signaling. Therefore, this study reveals a novel function of TGF-β signaling inhibition in the generation and maintenance of PSCs.