The combination of miR-122 overexpression and Let-7f silencing induces hepatic differentiation of adipose tissue-derived stem cells

Molecular mechanism underlying miR-204-5p regulation of adipose-derived stem cells differentiation into cells from three germ layers

The limited differentiation ability of adipose-derived stem cells (ADSCs) limits their application in stem cell therapy and regenerative medicine. Here, we explore the molecular mechanism by which miR-204-5p regulates ADSCs differentiation into cells derived from the three germ layers (i.e., adipocytes, neurocytes, and hepatocytes). Although miR-204-5p overexpression inhibited ADSCs differentiation into adipocytes, neurocyte and hepatocyte differentiation were promoted. Mechanistically, miR-204-5p inhibited the expression of PPARG by regulating the AMPK signaling pathway, thereby inhibiting ADSCs differentiation into adipocytes. Further, miR-204-5p regulated JAG1/NOTCH3 axis for the inhibition of differentiation into adipocytes and promotion of differentiation into neurocytes. miR-204-5p might also promote ADSCs differentiation into hepatocytes by upregulating E2F8. The findings of this study provide novel insights into the regulatory mechanisms underlying early embryonic development and will help to facilitate the application of ADSCs in stem cell therapy and regenerative medicine.

Gene Therapy Based on Mesenchymal Stem Cells Derived from Adipose Tissue for the Treatment of Obesity and Its Metabolic Complications

Obesity is a highly prevalent condition often associated with dysfunctional adipose tissue. Stem cell-based therapies have become a promising tool for therapeutic intervention in the context of regenerative medicine. Among all stem cells, adipose-derived mesenchymal stem cells (ADMSCs) are the most easily obtained, have immunomodulatory properties, show great ex vivo expansion capacity and differentiation to other cell types, and release a wide variety of angiogenic factors and bioactive molecules, such as growth factors and adipokines. However, despite the positive results obtained in some pre-clinical studies, the actual clinical efficacy of ADMSCs still remains controversial. Transplanted ADMSCs present a meager rate of survival and proliferation, possibly because of the damaged microenvironment of the affected tissues. Therefore, there is a need for novel approaches to generate more functional ADMSCs with enhanced therapeutic potential. In this context, genetic manipulation has emerged as a promising strategy. In the current review, we aim to summarize several adipose-focused treatments of obesity, including cell therapy and gene therapy. Particular emphasis will be given to the continuum from obesity to metabolic syndrome, diabetes, and underlying non-alcoholic fatty liver disease (NAFLD). Furthermore, we will provide insights into the potential shared adipocentric mechanisms involved in these pathophysiological processes and their remediation using ADMSCs.

Mir-122 upregulation and let-7f downregulation combination: The effects on hepatic differentiation of hiPSCs on the PCL-Gel-HA nanofibrous scaffold

Cell therapy and tissue engineering as promising candidates for the liver transplantation dilemma are of special interest. Induced pluripotent stem cells (iPSCs) are one of the best sources in this field, but their differentiation methods to hepatocytes have remained challenging. We transduced human iPSCs (hiPSCs) with miR-122 and off-let-7f (hiPSCs^{miR-122 + off-let-7f} ) to evaluate how they can differentiate hiPSCs to hepatocyte-like cells (HLCs) without any extrinsic growth factor. Additionally, we studied the effect of Poly ɛ-caprolactone-gelatin-hyaluronic acid (PCL-Gel-HA) nanofibrous scaffold as an extracellular matrix (ECM) simulator on differentiation improvement. Definitive endoderm markers (FOXA2 and SOX17), as well as hepatic markers (AFP, Albumin, CK18, HNF4α) expression, were significantly higher in hiPSCs^{miR-122 + off-let-7f} derived HLCs (hiPSCs-HLCs) compared to the control group (miR-scramble transduced hiPSCs: hiPSCs^scramble ). hiPSCs-HLCs indicated hepatocyte morphological characteristics and positive immunostaining for AFP, Albumin and HNF4α. Albumin and urea secretion were significantly higher in hiPSCs-HLCs than hiPSCs^scramble . Comparing these markers in the PCL-Gel-HA group with the tissue culture plate (TCP) group revealed that PCL-Gel-HA could improve differentiation towards HLCs significantly. Regarding our results, these microRNAs can be used to differentiate hiPSCs to the functional hepatocytes for disease modelling, drug screening and cell-based therapy in future studies.

Characteristics and expression profiles of circRNAs during abdominal adipose tissue development in Chinese Gushi chickens

Circular RNAs (circRNAs) play important roles in adipogenesis. However, studies on circRNA expression profiles associated with the development of abdominal adipose tissue are lacking in chickens. In this study, 12 cDNA libraries were constructed from the abdominal adipose tissue of Chinese domestic Gushi chickens at 6, 14, 22, and 30 weeks. A total of 1,766 circRNAs were identified by Illumina HiSeq 2500 sequencing. These circRNAs were primarily distributed on chr1 through chr10 and sex chromosomes, and 84.95% of the circRNAs were from gene exons. Bioinformatic analysis showed that each circRNA has 35 miRNA binding sites on average, and 62.71% have internal ribosome entry site (IRES) elements. Meanwhile, these circRNAs were primarily concentrated in TPM < 0.1 and TPM > 60, and their numbers accounted for 18.90% and 80.51%, respectively, exhibiting specific expression patterns in chicken abdominal adipose tissue. In addition, 275 differentially expressed (DE) circRNAs were identified by comparison analysis. Functional enrichment analysis showed that the parental genes of DE circRNAs were primarily involved in biological processes and pathways related to lipid metabolism, such as regulation of fat cell differentiation, fatty acid homeostasis, and triglyceride homeostasis, as well as fatty acid biosynthesis, fatty acid metabolism, and glycerolipid metabolism. Furthermore, ceRNA regulatory networks related to abdominal adipose development were constructed. The results of this study indicated that circRNAs can regulate lipid metabolism, adipocyte proliferation and differentiation, and cell junctions during abdominal adipose tissue development in chickens through complex ceRNA networks between circRNAs, miRNAs, genes, and pathways. The results of this study may help to expand the number of known circRNAs in abdominal adipose tissue and provide a valuable resource for further research on the function of circRNAs in chicken abdominal adipose tissue.

Pre-treatments enhance the therapeutic effects of mesenchymal stem cells in liver diseases

Liver diseases caused by viral infection, alcohol abuse and metabolic disorders can progress to end‐stage liver failure, liver cirrhosis and liver cancer, which are a growing cause of death worldwide. Although liver transplantation and hepatocyte transplantation are useful strategies to promote liver regeneration, they are limited by scarce sources of organs and hepatocytes. Mesenchymal stem cells (MSCs) restore liver injury after hepatogenic differentiation and exert immunomodulatory, anti‐inflammatory, antifibrotic, antioxidative stress and antiapoptotic effects on liver cells in vivo. After isolation and culture in vitro, MSCs are faced with nutrient and oxygen deprivation, and external growth factors maintain MSC capacities for further applications. In addition, MSCs are placed in a harsh microenvironment, and anoikis and inflammation after transplantation in vivo significantly decrease their regenerative capacity. Pre‐treatment with chemical agents, hypoxia, an inflammatory microenvironment and gene modification can protect MSCs against injury, and pre‐treated MSCs show improved hepatogenic differentiation, homing capacity, survival and paracrine effects in vitro and in vivo in regard to attenuating liver injury. In this review, we mainly focus on pre‐treatments and the underlying mechanisms for improving the therapeutic effects of MSCs in various liver diseases. Thus, we provide evidence for the development of MSC‐based cell therapy to prevent acute or chronic liver injury. Mesenchymal stem cells have potential as a therapeutic to prolong the survival of patients with end‐stage liver diseases in the near future.

MicroRNAs and their regulatory networks in Chinese Gushi chicken abdominal adipose tissue during postnatal late development

Background

Abdominal fat is the major adipose tissue in chickens. The growth status of abdominal fat during postnatal late development ultimately affects meat yield and quality in chickens. MicroRNAs (miRNAs) are endogenous small noncoding RNAs that regulate gene expression at the post-transcriptional level. Studies have shown that miRNAs play an important role in the biological processes involved in adipose tissue development. However, few studies have investigated miRNA expression profiles and their interaction networks associated with the postnatal late development of abdominal adipose tissue in chickens.

Results

We constructed four small RNA libraries from abdominal adipose tissue obtained from Chinese domestic Gushi chickens at 6, 14, 22, and 30 weeks. A total of 507 known miRNAs and 53 novel miRNAs were identified based on the four small RNA libraries. Fifty-one significant differentially expressed (SDE) miRNAs were identified from six combinations by comparative analysis, and the expression patterns of these SDE miRNAs were divided into six subclusters by cluster analysis. Gene ontology enrichment analysis showed that the SDE miRNAs were primarily involved in the regulation of fat cell differentiation, regulation of lipid metabolism, regulation of fatty acid metabolism, and unsaturated fatty acid metabolism in the lipid metabolism- or deposition-related biological process categories. In addition, we constructed differentially expressed miRNA–mRNA interaction networks related to abdominal adipose development. The results showed that miRNA families, such as mir-30, mir-34, mir-199, mir-8, and mir-146, may have key roles in lipid metabolism, adipocyte proliferation and differentiation, and cell junctions during abdominal adipose tissue development in chickens.

Conclusions

This study determined the dynamic miRNA transcriptome and characterized the miRNA–mRNA interaction networks in Gushi chicken abdominal adipose tissue for the first time. The results expanded the number of known miRNAs in abdominal adipose tissue and provide novel insights and a valuable resource to elucidate post-transcriptional regulation mechanisms during postnatal late development of abdominal adipose tissue in chicken.

Current understanding of adipose-derived mesenchymal stem cell-based therapies in liver diseases

The liver, the largest organ with multiple synthetic and secretory functions in mammals, consists of hepatocytes, cholangiocytes, hepatic stellate cells (HSCs), sinusoidal endothelial cells, Kupffer cells (KCs), and immune cells, among others. Various causative factors, including viral infection, toxins, autoimmune defects, and genetic disorders, can impair liver function and result in chronic liver disease or acute liver failure. Mesenchymal stem cells (MSCs) from various tissues have emerged as a potential candidate for cell transplantation to promote liver regeneration. Adipose-derived MSCs (ADMSCs) with high multi-lineage potential and self-renewal capacity have attracted great attention as a promising means of liver regeneration. The abundance source and minimally invasive procedure required to obtain ADMSCs makes them superior to bone marrow-derived MSCs (BMMSCs). In this review, we comprehensively analyze landmark studies that address the isolation, proliferation, and hepatogenic differentiation of ADMSCs and summarize the therapeutic effects of ADMSCs in animal models of liver diseases. We also discuss key points related to improving the hepatic differentiation of ADMSCs via exposure of the cells to cytokines and growth factors (GFs), extracellular matrix (ECM), and various physical parameters in in vitro culture. The optimization of culturing methods and of the transplantation route will contribute to the further application of ADMSCs in liver regeneration and help improve the survival rate of patients with liver diseases. To this end, ADMSCs provide a potential strategy in the field of liver regeneration for treating acute or chronic liver injury, thus ensuring the availability of ADMSCs for research, trial, and clinical applications in various liver diseases in the future.

Insulin-like growth factor-I promotes hepatic differentiation of human adipose tissue-derived stem cells

There are numerous studies which provide support for the use of human adipose tissue-derived stem cells (hASCs) to generate hepatocyte-like cells. However, the produced cells exhibit only a certain level of differentiation, mainly due to inefficient induction conditions. Therefore, based on the important role of insulin-like growth factor (IGF-I) in hepatic function and development, in the current study we evaluated the differentiation efficacy of the mentioned factor to induce hASCs into functional hepatocyte-like cells. To investigate this, using a two-step protocol, hASCs were treated with a combination of HGF, Dex, and OSM in the presence or absence of IGF-I up to 21 days. Hepatic differentiation was evaluated by analyzing specific hepatocyte markers at different time points of differentiation induction. Increased expression of hepatocyte-specific genes including ALB, AFP, CK18, and HNF4a, downregulation of bile duct cells marker (CK19), the higher number of ALB positive cells, increased urea production together with higher glycogen deposit was observed upon the treatment of hASCs with the induction medium containing IGF-I compared to the other treatment. In conclusion, our findings suggest IGF-I as a potent inducer of hepatic differentiation of hASCs and its potential to generate more functional hepatocyte-like cells.

Differentiation in stem/progenitor cells along fetal or adult hepatic stages requires transcriptional regulators independently of oscillations in microRNA expression

Understanding mechanisms in lineage differentiation is critical for organ development, pathophysiology and oncogenesis. To determine whether microRNAs (miRNA) may serve as drivers or adjuncts in hepatic differentiation, we studied human embryonic stem cell-derived hepatocytes and primary hepatocytes representing fetal or adult stages. Model systems were used for hepatic lineage advancement or regression under culture conditions with molecular assays. Profiles of miRNA in primary fetal and adult hepatocytes shared similarities and distinctions from pluripotent stem cells or stem cell-derived early fetal-like hepatocytes. During phenotypic regression in fetal or adult hepatocytes, miRNA profiles oscillated to regain stemness-associated features that had not been extinguished in stem cell-derived fetal-like hepatocytes. These oscillations in stemness-associated features were not altered in fetal-like hepatocytes by inhibitory mimics for dominantly-expressed miRNA, such as hsa-miR-99b, -100, -214 and -221/222. The stem cell-derived fetal-like hepatocytes were permissive for miRNA characterizing mature hepatocytes, including mimics for hsa-miR-122, -126, -192, -194 and -26b, although transfections of the latter did not advance hepatic differentiation. Examination of genome-wide mRNA expression profiles in stem cell-derived or primary fetal hepatocytes indicated targets of highly abundant miRNA regulated general processes, e.g., cell survival, growth and proliferation, functional maintenance, etc., without directing cell differentiation. Among upstream regulators of gene networks in stem cell-derived hepatocytes included HNF4A, SNAI1, and others, which affect transcriptional circuits directing lineage development or maintenance. Therefore, miRNA expression oscillated in response to microenvironmental conditions, whereas lineage-specific transcriptional regulators, such as HNF4A, were necessary for directing hepatic differentiation. This knowledge will be helpful for understanding the contribution of stem cells in pathophysiological states and oncogenesis, as well as for applications of stem cell-derived hepatocytes.

MicroRNA Let-7f-5p Promotes Bone Marrow Mesenchymal Stem Cells Survival by Targeting Caspase-3 in Alzheimer Disease Model

Widespread death of transplanted mesenchymal stem cells (MSCs) hampers the development of stem cell therapy for Alzheimer disease (AD). Cell pre-conditioning might help cope with this challenge. We tested whether let-7f-5p-modified MSCs could prolong the survival of MSCs after transplantation. When exposed to Aβ₂₅₋₃₅in vitro, MSCs showed significant early apoptosis with decrease in the let-7f-5p levels and increased caspase-3 expression. Upregulating microRNA let-7f-5p in MSCs alleviated Aβ₂₅₋₃₅-induced apoptosis by decreasing the caspase-3 levels. After computerized analysis and the luciferase reporter assay, we identified that caspases-3 was the target gene of let-7f-5p. In vivo, hematoxylin and eosin staining confirmed the success of MSCs transplantation into the lateral ventricles, and the let-7f-5p upregulation group showed the lowest apoptotic rate of MSCs detected by TUNEL immunohistochemistry analysis and immunofluorescence. Similarly, bioluminescent imaging showed that let-7f-5p upregulation moderately prolonged the retention of MSCs in brain. In summary, we identified the anti-apoptotic role of let-7f-5p in Aβ₂₅₋₃₅-induced cytotoxicity, as well as the protective effect of let-7f-5p on survival of grafted MSCs by targeting caspase-3 in AD models. These findings show a promising approach of microRNA-modified MSCs transplantation as a therapy for neurodegenerative diseases.