Definitive endoderm differentiation of human-induced pluripotent stem cells using signaling molecules and IDE1 in three-dimensional polymer scaffold

Reduction of Activin A gives rise to comparable expression of key definitive endoderm and mature beta cell markers

Aim: Cell therapies for diabetes rely on differentiation of stem cells into insulin-producing cells, which is complex and expensive. Our goal was to evaluate production costs and test ways to reduce it. Methods: Cost of Goods (COGs) analysis for differentiation was completed and the effects of replacement or reduction of the most expensive item was tested using qRT-PCR, immunohistochemistry, flow cytometry along with glucose-stimulated insulin release. Results: Activin A (AA) was responsible for significant cost. Replacement with small molecules failed to form definitive endoderm (DE). Reducing AA by 50% did not negatively affect expression of beta cell markers. Conclusion: Reduction of AA concentration is feasible without adversely affecting DE and islet-like cell differentiation, leading to significant cost savings in manufacturing.

A Comparative Study of Endoderm Differentiation Between Activin A and Small Molecules

Small molecules such as ROCK inhibitors (Fasudil) and inducer of definitive endoderm 1 (IDE1) can promote differentiation of definitive endoderm, but their effects remain controversial. Therefore, we attempted to verify the effect of these small molecules on promoting definitive endoderm differentiation and found that Fasudil or IDE1 alone could not achieve a similar effect as activin A. On the contrary, CHIR99021 could efficiently promote definitive endoderm differentiation. Nearly 43.4% of experimental cells were SRY-box transcription factor 17 (SOX17)-positive under the synergistic effect of IDE1 and CHIR99021, but its ability to differentiate towards definitive endoderm was still insufficient. Transcriptional analysis and comparison of IDE1 and CHIR99021 synergistic groups (IC) and activin A and CHIR99021 synergistic groups (AC) showed significantly down-regulated definitive endoderm markers in the IC group compared with those in the AC group and the differences between the two groups were mainly due to bone morphogenetic proteins (BMP4) and fibroblast growth factor 17 (FGF17). Further single-cell transcriptome analysis revealed lower expression of BMP4 in SOX17-positive populations, while mothers against decapentaplegic homolog (SMAD) protein translation signal and FGF17 in the AC group were higher than that in the IC group. Western blot analysis showed a significant difference in levels of p-SMAD2/3 between AC and IC groups, which suggests that regulating p-SMAD2/3 may provide a reference to improve the differentiation of definitive endoderm.

Simultaneous Administration of Berberine and Transplantation of Endometrial Stem Cell-Derived Insulin Precursor Cells on a Nanofibrous Scaffold to Treat Diabetes Mellitus in Mice

Today, significant success has been achieved in treating diabetes with cell therapy derived from various sources of stem and progenitors. The replacement of beta cells is one of the new diabetes treatment methods. To this end, the production of pancreatic beta precursors in cell culture has created an important research field for diabetes treatment. Endometrial stem cells were isolated using an enzymatic method, and after their identity was confirmed using a flow cytometry and differentiation potential assay, the isolated cells were cultured on an electrospun PCL/CS scaffold. Endometrial cells were differentiated into insulin-producing cells (IPCs), and gene expression was analyzed using the qRT-PCR and immunofluorescence to confirm the creation of IPCs. Then, IPCs on the scaffold along with berberine were applied to 5 groups of diabetic mice, and after 6 weeks, insulin, blood glucose, and weight of the animals were measured. The findings revealed that pancreatic markers were significantly expressed in IPCs compared to control cells. In addition, when compared to the control group and scaffolds, the receiving group of IPCs on scaffolds had a significant improvement (p ≤ 0.0015), and this improvement increased with the addition of berberine (decrease in blood sugar (133 mg/dL), and an increase in weight (5/39 g) and insulin (2.29 MIU/L). Thus, tissue engineering is a promising new strategy for treating diabetes and can be used in the future for cell therapy and suitable drugs for diabetic patients.

Generation of glucose sensitive insulin-secreting cells from human induced pluripotent stem cells on optimized polyethersulfone hybrid nanofibrous scaffold

BACKGROUND

In the realm of diabetes treatment, various strategies have been tried, including islet transplantation and common drug therapies, but the limitations of these procedures and lack of responsive to the high number of patients have prompted researchers to develop a new method. In recent decades, the use of stem cells and three-dimonsional (3D) scaffold to produce insulin-secreting cells is one of the most promising new approaches. Meanwhile, human-induced pluripotent stem cells (iPSCs) propose due to advantages such as autologousness and high pluripotency in cell therapy. This study aimed to evaluate the differentiation of iPSCs into pancreatic islet insuli-producing cells (IPCs) on Silk/PES (polyethersulfone) nanofibers as a 3D scaffold and compare it with a two-dimonsional (2D) cultured group.

METHODS

Investigating the functional, morphological, molecular, and cellular characteristics of differentiated iPSCs on control cultures (without differentiation medium), 2D and 3D were measured by various methods such as electron microscopy, Q-PCR, immunofluorescence, western blot, and ELISA.

RESULTS

This investigation revealed that differentiated cells on the 3D Silk/PES scaffold expressed pancreatic specific-markers such as insulin and pdx1 at higher levels than the control and 2D groups, with a significant difference between the two groups. All results of Q-PCR, immunocytochemistry, and western blot showed that IPCs in the silk/PES 3D group was more efficient than in the 2D group. In the face of these cases, the release of insulin and C-peptide in response to several concentrations of glucose in the 3D group was significantly higher than in the 2D culture.

CONCLUSION

Finally, our findings displayed that optimized Silk/PES 3D scaffolds can enhance the differentiation of IPCs from iPSCs compared to the 2D culture group.

The microenvironment of silk/gelatin nanofibrous scaffold improves proliferation and differentiation of Wharton's jelly-derived mesenchymal cells into islet-like cells

The use of umbilical cord-derived mesenchymal stem cells along with three-dimensional (3D) scaffolds in pancreatic tissue engineering can be considered as a treatment for diabetes. This study aimed to investigate the differentiation of Wharton's jelly-derived mesenchymal stem cells (WJ-MSCs) into pancreatic islet-insulin producing cells (IPCs) on silk/gelatin nanofibers as a 3D scaffold. Mesenchymal markers were evaluated at the mesenchymal stem cells (MSCs) level by flow cytometry. WJ-MSCs were then cultured on 3D scaffolds and treated with a differential medium. Immunocytochemical assays showed efficient differentiation of WJ-MSCs into IPCs. Also, Real-time PCR results showed a significant increase in the expression of pancreatic genes in the 3D culture group compared to the two-dimensional (2D) culture group. Despite these cases, the secretion of insulin and C-peptide in response to different concentrations of glucose in the 3D group was significantly higher than in the 2D culture. The results of our study showed that silk/gelatin scaffold with WJ-MSCs could be a good option in the production of IPCs in regenerative medicine and pancreatic tissue engineering.

Efficiently generate functional hepatic cells from human pluripotent stem cells by complete small-molecule strategy

BACKGROUND

Various methods have been developed to generate hepatic cells from human pluripotent stem cells (hPSCs) that rely on the combined use of multiple expensive growth factors, limiting industrial-scale production and widespread applications. Small molecules offer an attractive alternative to growth factors for producing hepatic cells since they are more economical and relatively stable.

METHODS

We dissect small-molecule combinations and identify the ideal cocktails to achieve an optimally efficient and cost-effective strategy for hepatic cells differentiation, expansion, and maturation.

RESULTS

We demonstrated that small-molecule cocktail CIP (including CHIR99021, IDE1, and PD0332991) efficiently induced definitive endoderm (DE) formation via increased endogenous TGF-β/Nodal signaling. Furthermore, we identified that combining Vitamin C, Dihexa, and Forskolin (VDF) could substitute growth factors to induce hepatic specification. The obtained hepatoblasts (HBs) could subsequently expand and mature into functional hepatocyte-like cells (HLCs) by the established chemical formulas. Thus, we established a stepwise strategy with complete small molecules for efficiently producing scalable HBs and functionally matured HLCs. The small-molecule-derived HLCs displayed typical functional characteristics as mature hepatocytes in vitro and repopulating injured liver in vivo.

CONCLUSION

Our current small-molecule-based hepatic generation protocol presents an efficient and cost-effective platform for the large-scale production of functional human hepatic cells for cell-based therapy and drug discovery using.

Advanced In Vitro Lung Models for Drug and Toxicity Screening: The Promising Role of Induced Pluripotent Stem Cells

The substantial socioeconomic burden of lung diseases, recently highlighted by the disastrous impact of the coronavirus disease 2019 (COVID-19) pandemic, accentuates the need for interventive treatments capable of decelerating disease progression, limiting organ damage, and contributing to a functional tissue recovery. However, this is hampered by the lack of accurate human lung research models, which currently fail to reproduce the human pulmonary architecture and biochemical environment. Induced pluripotent stem cells (iPSCs) and organ-on-chip (OOC) technologies possess suitable characteristics for the generation of physiologically relevant in vitro lung models, allowing for developmental studies, disease modeling, and toxicological screening. Importantly, these platforms represent potential alternatives for animal testing, according to the 3Rs (replace, reduce, refine) principle, and hold promise for the identification and approval of new chemicals under the European REACH (registration, evaluation, authorization and restriction of chemicals) framework. As such, this review aims to summarize recent progress made in human iPSC- and OOC-based in vitro lung models. A general overview of the present applications of in vitro lung models is presented, followed by a summary of currently used protocols to generate different lung cell types from iPSCs. Lastly, recently developed iPSC-based lung models are discussed.

Endoderm and mesoderm derivatives in embryonic stem cell differentiation and their use in developmental toxicity testing

Embryonic stem cell differentiation models have increasingly been applied in non-animal test systems for developmental toxicity. After the initial focus on cardiac differentiation, attention has also included an array of neuro-ectodermal differentiation routes. Alternative differentiation routes in the mesodermal and endodermal germ lines have received less attention. This review provides an inventory of achievements in the latter areas of embryonic stem cell differentiation, with a view to possibilities for their use in non-animal test systems in developmental toxicology. This includes murine and human stem cell differentiation models, and also gains information from the field of stem cell use in regenerative medicine. Endodermal stem cell derivatives produced in vitro include hepatocytes, pancreatic cells, lung epithelium, and intestinal epithelium, and mesodermal derivatives include cardiac muscle, osteogenic, vascular and hemopoietic cells. This inventory provides an overview of studies on the different cell types together with biomarkers and culture conditions that stimulate these differentiation routes from embryonic stem cells. These models may be used to expand the spectrum of embryonic stem cell based new approach methodologies in non-animal developmental toxicity testing.

Molecular study of the proliferation process of beta cells derived from pluripotent stem cells

BACKGROUND

Diabetes mellitus (DM) is a chronic metabolic disorder, increasing in the number of patients and poses a severe threat to human health. Significant advances have been made in DM treatment; the most important of which is differentiation and proliferation of beta cells from IPSCs.

METHODS

Data were collected from PUBMED at various time points up to the academic year of 2020. The related keywords are listed as follows: "Induced pluripotent stem cell", "Proliferation", "Growth factor", "Small molecule", "cardiotoxicity" and "Scaffold."

RESULT

The use of growth factors along with small molecules can be a good strategy for beta-cell proliferation. Also, proliferation of beta cells on nanofibers scaffolds can create a similar in vivo environment, that leads to increased function of beta-cell. Some transcription factors that cause beta cells proliferation play an important role in inflammation; so, it is essential to monitor them to prevent inflammation.

CONCLUSION

Finally, the simultaneous use of growth factors, micronutrients and scaffolds can be an excellent strategy to increase the proliferation and function of beta cells derived from IPSCs.

Promoting Maturation of Human Pluripotent Stem Cell-Derived Renal Microtissue by Incorporation of Endothelial and Mesenchymal Cells

Directed differentiation of human pluripotent stem cells (hPSCs) uses a growing number of small molecules and growth factors required for in vitro generation of renal lineage cells. Although current protocols are relatively inefficient or expensive. The first objective of the present work was to establish a new differentiation protocol for generating renal precursors. We sought to determine if inducer of definitive endoderm 1 (IDE1), a cost-effective small molecule, can be used to replace activin A. Gene expression data showed significantly increased expressions of nephrogenic markers in cells differentiated with 20 nM IDE1 compared with cells differentiated with activin A. Thus, renal lineage cells could be generated by this alternative approach. Afterward, we determined whether coculture of endothelial and mesenchymal cells could increase the maturation of three-dimensional (3D) renal structures. For this purpose, we employed a 3D coculture system in which hPSC-derived kidney precursors were cocultured with endothelial cells (ECs) and mesenchymal stem cells (MSCs), hereafter named RMEM (renal microtissue derived from coculture of renal precursors with endothelial and mesenchymal stem cells). hPSC-derived kidney precursors were cultured either alone [renal microtissue (RM)] or in coculture with human umbilical vein endothelial cells and human bone marrow-derived mesenchymal stem cells at an approximate ratio of 10:7:2, respectively. Immunofluorescent staining showed expressions of kidney-specific markers synaptopodin, LTL, and E-cadherin, as well as CD31⁺ ECs that were distributed throughout the RMEMs. Quantitative real-time polymerase chain reaction analysis confirmed a significant increase in gene expressions of the renal-specific markers in RMEMs compared with RMs. These findings demonstrated that renal precursors cocultured with endothelial and MSCs showed greater maturity compared with RMs. Moreover, ex ovo transplantation induced further maturation in the RMEM constructs. Our novel approach enabled the generation of RMEM that could potentially be used in high-throughput drug screening and nephrotoxicology studies.

Small Molecule Differentiate PDX1-Expressing Cells Derived from Human Endometrial Stem Cells on PAN Electrospun Nanofibrous Scaffold: Applications for the Treatment of Diabetes in Rat

In this study, we designed an engineered tissue and transplanted it to an animal model, trying to take an effective step toward meeting the needs of diabetic patients. Here, human endometrial cells were differentiated into PDX1-expressing cells using a small molecule of Y-27632 on polyacrylonitrile (PAN) electrospun scaffolds and transplanted into diabetic rats. PAN nanofibers were made by electrospinning. RT-PCR and immunocytochemical analysis were performed to express pancreatic precursor (PP) genes. The differentiated cells were then transplanted into the abdominal cavity of diabetic rats with Streptozotocin. In another group of rats, differentiated cells were injected through the tail. Blood glucose was measured 7, 14, and 28 days after transplantation, and rat weight was also measured. The results showed that the expression of PP markers including Sox-17, Ngn3, Pdx1, and NKx2.2 genes was significantly increased in differentiated cells compared to the control group. In diabetic rats receiving differentiated cells, both transplanted and injected, glucose concentration as well as body weight improved compared to the control group. Rats receiving transplants in the peritoneum had a lower blood glucose concentration than those in the cell receiving group by injection, and the cell receiving group in the form of injections was more effective in increasing the body weight of rats than in the other groups. According to the results of the study, the transplantation of PP from endometrium using PAN scaffolding at the site of peritoneum could be recommended for the treatment of diabetes, although further studies are needed to provide a complete cure.

Inhibition of LSD1 promotes the differentiation of human induced pluripotent stem cells into insulin-producing cells

BACKGROUND

Human induced pluripotent stem cells (hiPSCs) represent a potentially unlimited source of pancreatic endocrine lineage cells. Although insulin-producing β cells derived from hiPSCs have been successfully induced, much work remains to be done to achieve mature β cells. Lysine-specific demethylase 1 (LSD1) plays an important role in the regulation of hiPSC self-renewal and differentiation. We propose a new strategy to acquire insulin-producing cells (IPCs) from hiPSCs by knocking down LSD1.

METHODS

Knockdown of LSD1 in hiPSCs with five shRNA. Assessment of the effects of shRNA on hiPSC proliferation, cell cycle, and apoptosis. Using knockdown hiPSCs with 31.33% LSD1 activity, we achieved a four-step differentiation into IPCs and test its differentiation efficiency, morphology, and marker genes and proteins. We implanted the IPCs into the renal subcapsular of SCID-Beige diabetic mice to evaluate the hypoglycemic effect in vivo. We tested LSD1 and HDAC1 whether they are present in the CoREST complex through IP-WB, and analyzed LSD1, CoREST, HDAC1, H3K4me2/me3, and H3K27me3 protein expression before and after knockdown of LSD1.

RESULTS

Differentiated hiPSCs were 38.32% ± 3.54% insulin-positive cells and released insulin/C-peptide in response to glucose stimulus in a manner comparable to adult human islets. Most of the IPCs co-expressed mature β cell-specific markers. When transplanted under the left renal capsule of SCID-Beige diabetic mice, these IPCs reversed hyperglycemia, leading to a significant increase in the definitive endoderm cells. IP-WB results showed that LSD1, HDAC1, and CoREST formed a complex in hiPSCs. Chip-PCR results showed that LSD1, HDAC1, and CoREST were enriched in the same district during the SOX17 and FOXA2 promoter region. Inhibition of LSD1 would not affect the level of CoREST but decreased the HDAC1 expressions. The H3K4me2/me3 and H3K9act level of SOX17 and FOXA2 promoter region increased after inhibited of LSD1, and promoted transcriptional activation. The H3K4me2/me3 and H3K9act level of OCT4 and SOX2 promoter region decreased with the transcriptional repressed.

CONCLUSIONS

LSD1 regulated histone methylation and acetylation in promoter regions of pluripotent or endodermal genes. Our results suggest a highly efficient approach to producing IPCs from hiPSCs.

Liver Tissue Engineering as an Emerging Alternative for Liver Disease Treatment

Chronic liver diseases affect thousands of lives throughout the world every year. The shortage of liver donors for transplantation has been the main driving force to employ alternative methods such as liver tissue engineering (LTE) in fabricating a three-dimensional transplantable liver tissue or enhancing cell delivery techniques alleviating the need for liver donors. LTE consists of three components, cells, ECM (extracellular matrix), and signaling molecules, which we discuss the first and second. The three most common cell sources used in LTE are human and animal primary hepatocytes, and stem cells for different applications. Two major categories of ECM are used to mimic the microenvironment of these cells, named scaffolds and microbeads. Scaffolds have been made by numerous methods with a wide range of synthetic and natural biomaterials. Cell encapsulation has also been utilized by many polymeric biomaterials. To investigate their functions, many properties have been discussed in the literature, such as biochemical, geometrical, and mechanical properties, in both of these categories. Overall, LTE shows excellent potential in assisting hepatic disorders. However, some challenges exist that prevent the practical use of it clinically, making LTE an ongoing research subject in the scientific society.

Differentiation of endometrial stem cells into insulin-producing cells using signaling molecules and zinc oxide nanoparticles, and three-dimensional culture on nanofibrous scaffolds

Diabetes mellitus is the most common metabolic disorder with a high mortality and morbidity rate. A new promising strategy to treat DM is pancreatic tissue engineering. We described a 3D culture system accompanied by signaling factors to differentiate hEnSCs into IPCs in the presence of nZnO. We isolated EnSCs and cultured it in DMEM/F12 medium. Nanofibrous PLA/Cs scaffold was prepared through the electrospinning method. The morphological properties of the scaffolds and cells were evaluated by SEM. MTT assay was used to investigate the metabolic activity of the hEnSCs cultured on the scaffolds and a four-stage protocol was applied to differentiate hEnSCs. The differentiated cells were tested for pancreatic markers by immunocytochemistry, qRT-PCR and DTZ staining. The results of this study revealed that hEnSCs cultured on PLA/Cs scaffold and treated with nZnO can efficiently differentiate into IPCs. The examination of differentiated cell morphology showed their near similarity with pancreatic islet cells, and DTZ staining emphasized the presence of insulin granules inside their cytoplasm. Moreover, qRT-PCR and immunofluorescent staining results showed the efficient expression of specific gene markers of IPCs in resultant differentiated cells. Moreover, PLA/CS and nZnO were able to provide a good nanoenvironment for the differentiation of hEnSCs into IPCS the in presence of other molecules.

Electrospun Nanofibers for Diabetes: Tissue Engineering and Cell-Based Therapies

Diabetes mellitus is an autoimmune disease which causes loss of insulin secretion producing hyperglycemia by promoting progressive destruction of pancreatic β cells. An ideal therapeutic approach to manage diabetes mellitus is pancreatic β cells replacement. The aim of this review article was to evaluate the role of nanofibrous scaffolds and stem cells in the treatment of diabetes mellitus. Various studies have pointed out that application of electrospun biomaterials has considerably attracted researchers in the field of tissue engineering. The principles of cell therapy for diabetes have been reviewed in the first part of this article, while the usability of tissue engineering as a new therapeutic approach is discussed in the second part.

Microphysiological systems meet hiPSC technology - New tools for disease modeling of liver infections in basic research and drug development

Complex cell culture models such as microphysiological models (MPS) mimicking human liver functionality in vitro are in the spotlight as alternative to conventional cell culture and animal models. Promising techniques like microfluidic cell culture or micropatterning by 3D bioprinting are gaining increasing importance for the development of MPS to address the needs for more predictivity and cost efficiency. In this context, human induced pluripotent stem cells (hiPSCs) offer new perspectives for the development of advanced liver-on-chip systems by recreating an in vivo like microenvironment that supports the reliable differentiation of hiPSCs to hepatocyte-like cells (HLC). In this review we will summarize current protocols of HLC generation and highlight recently established MPS suitable to resemble physiological hepatocyte function in vitro. In addition, we are discussing potential applications of liver MPS for disease modeling related to systemic or direct liver infections and the use of MPS in testing of new drug candidates.

Chemically defined and xenogeneic-free differentiation of human pluripotent stem cells into definitive endoderm in 3D culture

In vitro differentiation of human pluripotent stem cells (hPSCs) into definitive endoderm (DE) represents a key step towards somatic cells of lung, liver and pancreas. For future clinical applications, mass production of differentiated cells at chemically defined conditions and free of xenogeneic substances is envisioned. In this study we adapted our previously published two-dimensional (2D) DE induction protocol to three-dimensional (3D) static suspension culture in the absence of the xenogeneic extracellular matrix Matrigel. Next, fetal calf serum and bovine serum albumin present in the standard medium were replaced by a custom-made and xeno-free B-27. This yielded in a chemically defined and xenogeneic-free 3D culture protocol for differentiation of hPSCs into DE at efficiencies similar to standard 2D conditions. This novel protocol successfully worked with different hPSC lines including hESCs and hiPSCs maintained in two different stem cell media prior to differentiation. DE cells obtained by our novel BSA-free 3D protocol could be further differentiated into PDX1- or NKX6.1-expressing pancreatic progenitor cells. Notably, upon DE differentiation, we also identified a CXCR4⁺/NCAM⁺/EpCAM^low cell population with reduced DE marker gene expression. These CXCR4⁺/NCAM⁺/EpCAM^low cells emerge as a result of Wnt/beta-catenin hyperactivation via elevated CHIR-99021 concentrations and likely represent misspecified DE.

Biomaterial Engineering for Controlling Pluripotent Stem Cell Fate

Pluripotent stem cells (PSCs) represent an exciting cell source for tissue engineering and regenerative medicine due to their self-renewal and differentiation capacities. The majority of current PSC protocols rely on 2D cultures and soluble factors to guide differentiation; however, many other environmental signals are beginning to be explored using biomaterial platforms. Biomaterials offer new opportunities to engineer the stem cell niches and 3D environments for exploring biophysical and immobilized signaling cues to further our control over stem cell fate. Here, we review the biomaterial platforms that have been engineered to control PSC fate. We explore how altering immobilized biochemical cues and biophysical cues such as dimensionality, stiffness, and topography can enhance our control over stem cell fates. Finally, we highlight biomaterial culture systems that assist in the translation of PSC technologies for clinical applications.

Therapeutic potential of human mesenchymal stem cells derived beta cell precursors on a nanofibrous scaffold: An approach to treat diabetes mellitus

Diabetes mellitus is an autoimmune and chronic disorder that is rapidly expanding worldwide due to increasing obesity. In the current study, we were able to design a reliable 3-dimensional differentiation process of human Wharton's jelly mesenchymal stem cells into pancreatic beta cell precursors (PBCPs) and detected that transplanted PBCPs could improve hyperglycemia in a diabetes-induced model in mice. Polylactic acid/chitosan nanofibrous scaffold was prepared using an electrospinning method. Quantitative real-time reverse transcription-polymerase chain reaction and immunocytochemistry analysis were carried out to assess pancreatic marker expression in the differentiated cells. PBCPs were transplanted under the kidney capsule of diabetic mice that induced streptozotocin injection 14 days before the transplantation. Moreover, an intraperitoneal glucose tolerance test (ipGTT) was carried out 2 and 4 weeks after the transplantation to measure the reaction to a sudden increase of the blood glucose level in the transplanted animals. The results indicated that the expression of SRY (sex determining region Y)-box (Sox17), forkhead box A2 (FoxA2), pancreatic and duodenal homeobox 1 (Pdx1), neurogenin 3 (Ngn3), hepatic nuclear factor 4, alpha (Hnf4α), and NK2 homeobox 2 (Nkx2.2) were increased significantly in the differentiated cells compared with that of the control group. In the current study, the diabetic disease was confirmed by measuring blood glucose and proved by conducting some other behavioral tests. After the PBCPs transplantation in a diabetic model, the ipGTT and hyperglycemia investigation during the determinant times confirmed the disease's significant improvement in the experimental models. In this study, some preclinical data suggested that the transplantation of PBCPs associated with appropriate nanofiber scaffold can be utilized for the treatment of diabetes models. In addition, studies are required to elucidate the molecular mechanism of PBCPs acting in diabetes models before being used for patients with diabetes.

Current status of stem cell therapy, scaffolds for the treatment of diabetes mellitus

Diabetes mellitus (DM) remains the 7th leading cause of death in the world. Daily insulin injection is one component of a treatment plan for people with Diabetes mellitus type 1 (T1DM) that restores normal or near-normal blood sugar levels. However, Insulin treatment depends upon a variety of individual factors and leads to poor and drastic glycemic control. The need for an effective cell replacement strategy will be the aim of future clinical trials. Therefore, the aim of this systematic review is to outline the latest advances in scaffolding and stem cell therapy as a non-pharmacologic treatment for T1DM. It also emphasizes on some pancreas differentiation protocols and the clinical trials associated with stem cell therapy regarding T1DM in vitro and in vivo.

Vg1-Nodal heterodimers are the endogenous inducers of mesendoderm

Nodal is considered the key inducer of mesendoderm in vertebrate embryos and embryonic stem cells. Other TGF-beta-related signals, such as Vg1/Dvr1/Gdf3, have also been implicated in this process but their roles have been unclear or controversial. Here we report that zebrafish embryos without maternally provided vg1 fail to form endoderm and head and trunk mesoderm, and closely resemble nodal loss-of-function mutants. Although Nodal is processed and secreted without Vg1, it requires Vg1 for its endogenous activity. Conversely, Vg1 is unprocessed and resides in the endoplasmic reticulum without Nodal, and is only secreted, processed and active in the presence of Nodal. Co-expression of Nodal and Vg1 results in heterodimer formation and mesendoderm induction. Thus, mesendoderm induction relies on the combination of two TGF-beta-related signals: maternal and ubiquitous Vg1, and zygotic and localized Nodal. Modeling reveals that the pool of maternal Vg1 enables rapid signaling at low concentrations of zygotic Nodal.

All animals begin life as just one cell – a fertilized egg. In order to make a recognizable adult, each embryo needs to make the three types of tissue that will eventually form all of the organs: endoderm, which will form the internal organs; mesoderm, which will form the muscle and bones; and ectoderm, which will generate the skin and nervous system.

All vertebrates – animals with backbones like fish and humans – use the so-called Nodal signaling pathway to make the endoderm and mesoderm. Nodal is a signaling molecule that binds to receptors on the surface of cells. If Nodal binds to a receptor on a cell, it instructs that cell to become endoderm or mesoderm. As such, Nodal is critical for vertebrate life. However, there has been a 30-year debate in the field of developmental biology about whether a protein called Vg1, which has a similar molecular structure as Nodal, plays a role in the early development of vertebrates.

Zebrafish are often used to study animal development, and Montague and Schier decided to test whether these fish need the gene for Vg1 (also known as Gdf3) by deleting it using a genome editing technique called CRISPR/Cas9. It turns out that female zebrafish can survive without this gene. Yet, when the offspring of these females do not inherit the instructions to make Vg1 from their mothers, they fail to form the endoderm and mesoderm. This means that the embryos do not have hearts, blood or other internal organs, and they die within three days. Two other groups of researchers have independently reported similar results.

The findings reveal that Vg1 is critical for the Nodal signaling pathway to work in zebrafish. Montague and Schier then showed that, in this pathway, Nodal does not activate its receptors on its own. Instead, Nodal must interact with Vg1, and it is this Nodal-Vg1 complex that activates receptors, and instructs cells to become endoderm and mesoderm.

Scientists currently use the Nodal signaling pathway to induce human embryonic stem cells growing in the laboratory to become mesoderm and endoderm. As such, these new findings could ultimately help researchers to grow tissues and organs for human patients.

Biocompatible agarose-chitosan coated silver nanoparticle composite for soft tissue engineering applications

With increasing gap in the demand and supply of vital organs for transplantation there is a pressing need to bridge the gap with substitutes. One way to make substitutes is by tissue engineering which involves combining several types of synthetic or biomaterials, cells and growth factors cross-linked together to synthesize a functional scaffold for repair or replacement of non-functional organs. Nanoparticle based composites are gaining importance in tissue engineering due to their ability to enhance cell attachment and proliferation. The current study focuses on synthesizing agarose composites embedded with chitosan-coated silver nanoparticles using glutaraldehyde as the cross-linker. The synthesis of chitosan coated silver nanoparticles within the scaffold was confirmed with UV-visible spectroscopy. Physical and chemical characterization of the synthesized nanoparticles were done by XRD, FTIR, TGA and SEM. DMA showed higher mechanical strength of the scaffolds. The scaffolds showed degradation of ∼37% within a span of four weeks. The higher physical support provided by the synthesized scaffolds was shown by in-vitro cell viability assay. Broad spectrum anti-bacterial activity and superior hemocompatibility further showed the advantage it offered for growing cells. Thus a biopolymer based nanocomposite was synthesized, with intended widespread use as scaffold for engineering of soft tissues due to its enhanced biocompatibility and greater surface area for cell growth.

Differential effect of Activin A and WNT3a on definitive endoderm differentiation on electrospun nanofibrous PCL scaffold

The first step in the formation of hepatocytes and beta cells is the generation of definitive endoderm (DE) which involves a central issue in developmental biology. Human induced pluripotent stem cells (hiPSCs) have the pluripotency to differentiate into all three germ layers in vitro and have been considered potent candidates for regenerative medicine as an unlimited source of cells for therapeutic applications. In this study, we investigated the differentiating potential of hiPSCs on poly (ε-caprolactone) (PCL) nanofibrous scaffold into DE cells. Here, we demonstrate directed differentiation of hiPSCs by factors such as Activin A and Wnt3a. The differentiation was determined by immunofluoresence staining with Sox17, FoxA2 and Goosecoid (Gsc) and also by qRT-PCR analysis. The results of this study showed that hiPSCs, as a new cell source, have the ability to differentiate into DE cells with a high capacity and also demonstrate that three dimension (3D) culture provides a suitable nanoenviroment for growth, proliferation and differentiation of hiPSCs. PCL nanofibrous scaffold with essential supplements, stimulating factors and EB-derived cells is able to provide a novel method for enhancing functional differentiation of hiPSCs into DE cells.