Deep sequencing reveals complex mechanisms of microRNA regulation during retinoic acid-induced neuronal differentiation of mesenchymal stem cells

Non-canonical retinoid signaling in neural development, regeneration and synaptic function

Canonical retinoid signaling via nuclear receptors and gene regulation is critical for the initiation of developmental processes such as cellular differentiation, patterning and neurite outgrowth, but also mediates nerve regeneration and synaptic functions in adult nervous systems. In addition to canonical transcriptional regulation, retinoids also exert rapid effects, and there are now multiple lines of evidence supporting non-canonical retinoid actions outside of the nucleus, including in dendrites and axons. Together, canonical and non-canonical retinoid signaling provide the precise temporal and spatial control necessary to achieve the fine cellular coordination required for proper nervous system function. Here, we examine and discuss the evidence supporting non-canonical actions of retinoids in neural development and regeneration as well as synaptic function, including a review of the proposed molecular mechanisms involved.

Human umbilical cord mesenchymal stem cells express cholinergic neuron markers during co-culture with amniotic membrane cells and retinoic acid induction

Background: A wide variety of cytokines are released from human amniotic membrane cells (hAMCs), which can increase the rate of differentiation of mesenchymal stem cells into the neurons. We studied the effect of Retinoic Acid (RA) on the differentiation rate of human Umbilical Cord Mesenchymal Stem Cells (hUMSCs) which were co-cultured with hAMCs. Methods: In this experimental study, both hUMSCs and hAMCs were isolated from postpartum human umbilical cords and placenta respectively. The expression of mesenchymal (CD73, CD90 and CD105), hematopoietic and endothelial (CD34 and CD45) markers in hUMSCs were confirmed by flow cytometry. The hUMSCs were cultured in four distinct groups: group 1) Control, group 2) Co-culture with hAMCs, group 3) RA treatment and group 4) Co-culture with hAMCs treated by RA. Twelve days after culturing, the expression of NSE, MAP2 and ChAT differentiation genes and their related proteins were examined by real-time PCR and immunocytochemistry respectively. Results: The flow-cytometry analysis indicated increased expression of mesenchymal markers and a low expression of both hematopoietic and endothelial markers (CD73:98.24%, CD90: 97.32%, CD105: 90.75%, CD34: 2.96%, and CD45:1.74%). Moreover, the expression of both NSE and MAP2 markers was increased significantly in all studied groups in comparison to the control group On the other hand, the expression of ChAT had a significant increase in the group 2 and 4 (RA and RA+ co-culture). Conclusion: RA can be used as an effective inducer to differentiate hUMSCs into cholinergic-like cells, and hAMCs could increase the number of differentiated cells as an effective factor.

Nutraceutical regulation of miRNAs involved in neurodegenerative diseases and brain cancers

The human brain is a well-connected, intricate network of neurons and supporting glial cells. Neurodegenerative diseases arise as a consequence of extensive loss of neuronal cells leading to disruption of their natural structure and function. On the contrary, rapid proliferation and growth of glial as well as neuronal cells account for the occurrence of malignancy in brain. In both cases, the molecular microenvironment holds pivotal importance in the progression of the disease. MicroRNAs (miRNA) are one of the major components of the molecular microenvironment. miRNAs are small, noncoding RNAs that control gene expression post-transcriptionally. As compared to other tissues, the brain expresses a substantially high number of miRNAs. In the early stage of neurodegeneration, miRNA expression upregulates, while in oncogenesis, miRNA expression is gradually lost. Neurodegeneration and brain cancer is presumed to be under the influence of identical pathways of cell proliferation, differentiation and cell death which are tightly regulated by miRNAs. It has been confirmed experimentally that miRNA expression can be regulated by nutraceuticals - macronutrients, micronutrients or natural products derived from food; thereby making dietary supplements immensely significant for targeting miRNAs having altered expression patterns during neurodegeneration or oncogenesis. In this review, we will discuss in detail, about the common miRNAs involved in brain cancers and neurodegenerative diseases along with the comprehensive list of miRNAs involved separately in both pathological conditions. We will also discuss the role of nutraceuticals in the regulation of those miRNAs which are involved in both of these pathological conditions.

The Expression Profile of Dental Pulp-Derived Stromal Cells Supports Their Limited Capacity to Differentiate into Adipogenic Cells

Mesenchymal stromal cells (MSCs) can self-renew, differentiate into specialised cells and have different embryonic origins-ectodermal for dental pulp-derived MSCs (DPSCs) and mesodermal for adipose tissue-derived MSCs (ADSCs). Data on DPSCs adipogenic differentiation potential and timing vary, and the lack of molecular and genetic information prompted us to gain a better understanding of DPSCs adipogenic differentiation potential and gene expression profile. While DPSCs differentiated readily along osteogenic and chondrogenic pathways, after 21 days in two different types of adipogenic induction media, DPSCs cultures did not contain lipid vacuoles and had low expression levels of the adipogenic genes proliferator-activated receptor gamma (PPARG), lipoprotein lipase (LPL) and CCAAT/enhancer-binding protein alpha (CEBPA). To better understand this limitation in adipogenesis, transcriptome analysis in undifferentiated DPSCs was carried out, with the ADSC transcriptome used as a positive control. In total, 14,871 transcripts were common to DPSCs and ADSCs, some were unique (DPSCs: 471, ADSCs: 1032), and 510 were differentially expressed genes. Detailed analyses of overrepresented transcripts showed that DPSCs express genes that inhibit adipogenic differentiation, revealing the possible mechanism for their limited adipogenesis.

Retinoic acid and microRNA

Retinoic acid (RA), the biologically active metabolite of vitamin A, regulates a vast spectrum of biological processes, such as cell differentiation, proliferation, apoptosis, and morphogenesis. microRNAs (miRNAs) play a crucial role in regulating gene expression by binding to messenger RNA (mRNA) which leads to mRNA degradation and/or translational repression. Like RA, miRNAs regulate multiple biological processes, including proliferation, differentiation, apoptosis, neurogenesis, tumorigenesis, and immunity. In fact, RA regulates the expression of many miRNAs to exert its biological functions. miRNA and RA regulatory networks have been studied in recent years. In this manuscript, we summarize literature that highlights the impact of miRNAs in RA-regulated molecular networks included in the PubMed.

The Cellular and Molecular Patterns Involved in the Neural Differentiation of Adipose-Derived Stem Cells

Injuries to the nervous system cause serious problems among affected patients by preventing them from the possibility of living a normal life. As this tissue possesses a reduced capacity of self-regeneration currently, lots of different strategies are being developed in order to make the regeneration in the nervous system possible. Among them, tissue engineering and stem cell-based therapies are to date very exploded fields and tremendous progress has been made in this direction. As the two main components of the nervous system, react differently to injuries and behave different during disease, it is clear that two separate regeneration approaches have been taken into consideration during development of treatment. Special attention is constantly given to the potential of adipose-derived stem cells for this kind of application. Due to the fact that they present remarkable properties, they can easily be obtained and have demonstrated that are capable of engaging in neural and glial lineages, adipose-derived stem cells are promising tools for the field of nervous system regeneration. Moreover, new insights into epigenetic control and modifications during the differentiation of adipose-derived stem cells towards the neural liege could provide new methods to maximize the regeneration process. In this review, we summarize the current applications of adipose-derived stem cells for neural regeneration and discuss in-depth molecular patterns involved in the differentiation of adipose-derived stem cells in neuron-like cells and Schwann-like cells.

Gene expression profiling of human bone marrow mesenchymal stem cells during osteogenic differentiation

OBJECTIVE

Osteogenesis is a multiple-step process through which osteoblasts are derived from bone marrow mesenchymal stem cells (MSCs) with multilineage differentiation potential. This study aimed to analyze gene expression profiling during osteogenic differentiation of MSCs.

MATERIALS AND METHODS

Human MSCs were isolated and induced for differentiation in osteogenic medium. Full-genome gene expression microarrays and gene ontology analysis were performed.

RESULTS

A total of 1,680 differentially expressed genes in differentiated MSCs were identified including 430 upregulated and 1,250 downregulated. Moreover, pathway-act-network analysis showed that cell cycle, p53 signaling pathway and focal adhesion, had high degree (>5). The ribonucleotide reductase M1, thymidine kinase 1 and histone cluster 1 H3e also showed high degree (>10). Polymerase chain reaction analysis confirmed the differential expression of insulin-like growth factor binding protein 3, SMAD family member 3, transforming growth factor beta 2, and fibroblast growth factor 14 in differentiated MSCs.

CONCLUSIONS

Gene expression profiling provides a foundation to reveal the mechanisms that regulate osteogenic differentiation of MSCs.