Transdifferentiation Of Mesenchymal Stem Cells Research Articles

Critical View on Mesenchymal Stromal Cells in Regenerative Medicine.

The belief in the potency of stem cells has resulted in the medical applications of numerous cell types for organ repair, often with the low adherence to methodological stringency. Such uncritical enthusiasm is mainly presented in the approaches employing so-called mesenchymal stem cells (MSC), for the treatment of numerous, unrelated conditions. However, it should be stressed that such broad clinical applications of MSC are mostly based on the belief that MSC can efficiently differentiate into multiple cell types, not only osteoblasts, chondrocytes and adipose cells. Recent Advances: Studies employing lineage tracing established more promising markers to characterize MSC identity and localization in vivo and confirmed the differences between MSC isolated from various organs. Furthermore, preclinical and clinical experiments proved that transdifferentiation of MSC is unlikely to contribute to repair of numerous tissues, including the heart. Therefore, the salvage hypotheses, like MSC fusion with cells in target organs or the paracrine mechanisms, were proposed to justify the widespread application of MSC and to explain transient, if any, effects. The lack of standardization concerning the cells markers, their origin and particularly the absence of stringent functional characterization of MSC, leads to propagation of the worrying hype despite the lack of convincing therapeutic efficiency of MSC. The adherence to rigorous methodological rules is necessary to prevent the application of procedures which can be dangerous for patients and scientific research on the medical application of stem cells. Antioxid. Redox Signal. 00, 000-000.

Proteomic analysis of mesenchymal to Schwann cell transdifferentiation

While transplantation of Schwann cells facilitates axon regeneration, remyelination and repair after peripheral nerve injury clinical use is limited by cell bioavailability. We posit that such limitation in cell access can be overcome by the use of autologous bone-marrow derived mesenchymal stem cells (MSCs). As MSCs can transdifferentiate to Schwann cell-phenotypes and accelerate nerve regeneration we undertook proteomic evaluation of the cells to uncover the protein contents that affects Schwann cell formulation. Transdifferentiated MSCs secrete significant amounts of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) in cell-conditioned media that facilitated neurite outgrowth. MSC proteins significantly regulated during Schwann cell transdifferentiation included, but were not limited to, GNAI2, MYL9, ACTN4, ACTN1, ACTB, CAV-1, HSPB1, PHB2, TBB4B, CTGF, TGFI1, ARF6, EZR, GELS, VIM, WNT5A, RTN4, EFNB1. These support axonal guidance, myelination, neural development and neural growth and differentiation. The results unravel the molecular events that underlie cell transdifferentiation that ultimately serve to facilitate nerve regeneration and repair in support of cell transplantation. Significance statementWhile Schwann cells facilitate axon regeneration, remyelination and repair after peripheral nerve injury clinical use is limited by cell bioavailability. We posit that such limitation in cell access can be overcome by the use of bone-marrow derived mesenchymal stem cells (MSCs) transdifferentiated to Schwann cell-phenotypes. In the present study, we undertook the first proteomic evaluation of these transdifferentiated cells to uncover the protein contents that affects Schwann cell formulation. Furthermore, these transdifferentiated MSCs secrete significant amounts of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) in cell-conditioned media that facilitated neurite outgrowth. Our results demonstrate that a number of MSC proteins were significantly regulated following transdifferentiation of the MSCs supporting roles in axonal guidance, myelination, neural development and differentiation. The conclusions of the present work unravel the molecular events that underlie cell transdifferentiation that ultimately serve to facilitate nerve regeneration and repair in support of cell transplantation. Our study was the first proteomic comparison demonstrating the transdifferentiation of MSCs and these reported results can affect a wide field of stem cell biology, tissue engineering, and proteomics.

Early-stage detection of VE-cadherin during endothelial differentiation of human mesenchymal stem cells using SPR biosensor

Surface plasmon resonance (SPR) biosensors are most commonly applied for real-time dynamic analysis and measurement of interactions in bio-molecular studies and cell–surface analysis without the need for labeling processes. Up to present, SPR application in stem cell biology and biomedical sciences was underused. Herein, a very simple and sensitive method was developed to evaluate human mesenchymal stem cells trans-differentiation to endothelial lineage of over a period of 14 days based on VE-cadherin biomarker. The SPR signals increased with the increase of the amount of VE-cadherin expression on the cell surface during cell differentiation process. The method was able to detect ≈27 cells permm2. No significant effect was observed on the cell viability during the cell attachment to the surface of immune-reactive biochips and during the SPR analysis. Using this highly sensitive SPR method, it was possible to sense the early stage of endothelial differentiation on day 3 in label-free form, whereas flow cytometry and fluorescent microscopy methods were found unable to detect the cell differentiation at the same time. Therefore, the proposed method can rapidly and accurately detect cell differentiation in live cells and label-free manner without any need of cell breakage and has great potential for both diagnostic and experimental approaches.

Gelatin-based 3D conduits for transdifferentiation of mesenchymal stem cells into Schwann cell-like phenotypes.

This manuscript focuses on the effect of microstructure and mechanical properties of gelatin-based 3D conduits on the transdifferentiation of mesenchymal stem cells to Schwann cell-like phenotypes. This work builds on our recently accepted manuscript in Acta Biomaterialia focused on multifunctional 2D films, and focuses on 3D microstructured conduits designed to overcome limitations of current strategies to facilitate peripheral nerve regeneration. The comparison between conduits fabricated with nanofibrous, macroporous and ladder-like microstructures showed that the ladder-like conduits showed the most favorable environment for MSC transdifferentiation to Schwann-cell like phenotypes, as seen by both immunolabeling as well as secretion of neurotrophic factors. This work demonstrates the importance of controlling the 3D microstructure to facilitate tissue engineering strategies involving stem cells that can serve as promising approaches for peripheral nerve regeneration.

Neuron-Specific Fluorescence Reporter-Based Live Cell Tracing for Transdifferentiation of Mesenchymal Stem Cells into Neurons by Chemical Compound.

Although transdifferentiation of mesenchymal stem cells (MSCs) into neurons increases the possibility of therapeutic use of MSCs for neurodevelopmental disorders, the use of MSCs has the limitation on differentiation efficiency to neuronal lineage and lack of an easy method to monitor the transdifferentiation. In this study, using time-lapse live cell imaging, we assessed the neuronal differentiation of MSCs induced by a small molecule “NHPDQC (N-hydroxy-2-oxo-3-(3-phenylprophyl)-1,2-dihydroquinoxaline-6-carboxamide, C18H17N3O3).” Plasmid vector containing red fluorescence reporter genes under the control of the tubulin α1 (Tα1) promoter (pTα1-DsRed2) traced the neuronal differentiation of MSCs. Two days after NHPDQC treatment, MSCs showed neuron-like phenotype with neurite outgrowth and high expression of neuron-specific markers in more than 95% cells. The fluorescence signals increased in the cytoplasm of pTα1-DsRed2-transfected MSCs after NHPDQC treatment. In vitro monitoring of MSCs along the time courses showed progressive increase of fluorescence till 30 h after treatment, corresponding with the increase in neurite length. We examined an efficient neuronal differentiation of MSCs by NHPDQC alone and monitored the temporal changes of neuronal differentiation by neuron-specific fluorescence reporter along time. This method would help further our understanding of the differentiation of MSCs to produce neurons by simple treatment of small molecule.

Fusion of Human Fetal Mesenchymal Stem Cells with "Degenerating" Cerebellar Neurons in Spinocerebellar Ataxia Type 1 Model Mice.

Mesenchymal stem cells (MSCs) migrate to damaged tissues, where they participate in tissue repair. Human fetal MSCs (hfMSCs), compared with adult MSCs, have higher proliferation rates, a greater differentiation capacity and longer telomeres with reduced senescence. Therefore, transplantation of quality controlled hfMSCs is a promising therapeutic intervention. Previous studies have shown that intravenous or intracortical injections of MSCs result in the emergence of binucleated cerebellar Purkinje cells (PCs) containing an MSC-derived marker protein in mice, thus suggesting a fusion event. However, transdifferentiation of MSCs into PCs or transfer of a marker protein from an MSC to a PC cannot be ruled out. In this study, we unequivocally demonstrated the fusion of hfMSCs with murine PCs through a tetracycline-regulated (Tet-off) system with or without a Cre-dependent genetic inversion switch (flip-excision; FLEx). In the FLEx-Tet system, we performed intra-cerebellar injection of viral vectors expressing tetracycline transactivator (tTA) and Cre recombinase into either non-symptomatic (4-week-old) or clearly symptomatic (6–8-month-old) spinocerebellar ataxia type 1 (SCA1) mice. Then, the mice received an injection of 50,000 genetically engineered hfMSCs that expressed GFP only in the presence of Cre recombinase and tTA. We observed a significant emergence of GFP-expressing PCs and interneurons in symptomatic, but not non-symptomatic, SCA1 mice 2 weeks after the MSC injection. These results, together with the results obtained using age-matched wild-type mice, led us to conclude that hfMSCs have the potential to preferentially fuse with degenerating PCs and interneurons but not with healthy neurons.

Rebuilding the Damaged Heart: Mesenchymal Stem Cells, Cell-Based Therapy, and Engineered Heart Tissue.

Mesenchymal stem cells (MSCs) are broadly distributed cells that retain postnatal capacity for self-renewal and multilineage differentiation. MSCs evade immune detection, secrete an array of anti-inflammatory and anti-fibrotic mediators, and very importantly activate resident precursors. These properties form the basis for the strategy of clinical application of cell-based therapeutics for inflammatory and fibrotic conditions. In cardiovascular medicine, administration of autologous or allogeneic MSCs in patients with ischemic and nonischemic cardiomyopathy holds significant promise. Numerous preclinical studies of ischemic and nonischemic cardiomyopathy employing MSC-based therapy have demonstrated that the properties of reducing fibrosis, stimulating angiogenesis, and cardiomyogenesis have led to improvements in the structure and function of remodeled ventricles. Further attempts have been made to augment MSCs' effects through genetic modification and cell preconditioning. Progression of MSC therapy to early clinical trials has supported their role in improving cardiac structure and function, functional capacity, and patient quality of life. Emerging data have supported larger clinical trials that have been either completed or are currently underway. Mechanistically, MSC therapy is thought to benefit the heart by stimulating innate anti-fibrotic and regenerative responses. The mechanisms of action involve paracrine signaling, cell-cell interactions, and fusion with resident cells. Trans-differentiation of MSCs to bona fide cardiomyocytes and coronary vessels is also thought to occur, although at a nonphysiological level. Recently, MSC-based tissue engineering for cardiovascular disease has been examined with quite encouraging results. This review discusses MSCs from their basic biological characteristics to their role as a promising therapeutic strategy for clinical cardiovascular disease.

Mechanical Stretching Promotes Skin Tissue Regeneration via Enhancing Mesenchymal Stem Cell Homing and Transdifferentiation.

Skin tissue expansion is a clinical procedure for skin regeneration to reconstruct cutaneous defects that can be accompanied by severe complications. The transplantation of mesenchymal stem cells (MSCs) has been proven effective in promoting skin expansion and helping to ameliorate complications; however, systematic understanding of its mechanism remains unclear. MSCs from luciferase-Tg Lewis rats were intravenously transplanted into a rat tissue expansion model to identify homing and transdifferentiation. To clarify underlying mechanisms, a systematic approach was used to identify the differentially expressed genes between mechanically stretched human MSCs and controls. The biological significance of these changes was analyzed through bioinformatic methods. We further investigated genes and pathways of interest to disclose their potential role in mechanical stretching-induced skin regeneration. Cross sections of skin samples from the expanded group showed significantly more luciferase(+) and stromal cell-derived factor 1α (SDF-1α)(+), luciferase(+)keratin 14(+), and luciferase(+)CD31(+) cells than the control group, indicating MSC transdifferentiation into epidermal basal cells and endothelial cells after SDF-1α-mediated homing. Microarray analysis suggested upregulation of genes related to hypoxia, vascularization, and cell proliferation in the stretched human MSCs. Further investigation showed that the homing of MSCs was blocked by short interfering RNA targeted against matrix metalloproteinase 2, and that mechanical stretching-induced vascular endothelial growth factor A upregulation was related to the Janus kinase/signal transducer and activator of transcription (Jak-STAT) and Wnt signaling pathways. This study determines that mechanical stretching might promote skin regeneration by upregulating MSC expression of genes related to hypoxia, vascularization, and cell proliferation; enhancing transplanted MSC homing to the expanded skin; and transdifferentiation into epidermal basal cells and endothelial cells. Skin tissue expansion is a clinical procedure for skin regeneration to cover cutaneous defects that can be accompanied by severe complications. The transplantation of mesenchymal stem cells (MSCs) has been proven effective in promoting skin expansion and ameliorating complications. This study, which sought to provide a systematic understanding of the mechanism, determined that mechanical stretching could upregulate MSC expression of genes related to hypoxia, vascularization, and cell proliferation; enhance transplanted MSC homing to the expanded skin tissue; and promote their transdifferentiation into epidermal basal cells and endothelial cells.

The Impact of Epigenetics on Mesenchymal Stem Cell Biology.

Changes in epigenetic marks are known to be important regulatory factors in stem cell fate determination and differentiation. In the past years, the investigation of the epigenetic regulation of stem cell biology has largely focused on embryonic stem cells (ESCs). Contrarily, less is known about the epigenetic control of gene expression during differentiation of adult stem cells (AdSCs). Among AdSCs, mesenchymal stem cells (MSCs) are the most investigated stem cell population because of their enormous potential for therapeutic applications in regenerative medicine and tissue engineering. In this review, we analyze the main studies addressing the epigenetic changes in MSC landscape during in vitro cultivation and replicative senescence, as well as follow osteocyte, chondrocyte, and adipocyte differentiation. In these studies, histone acetylation, DNA methylation, and miRNA expression are among the most investigated phenomena. We describe also epigenetic changes that are associated with in vitro MSC trans-differentiation. Although at the at initial stage, the epigenetics of MSCs promise to have profound implications for stem cell basic and applied research. J. Cell. Physiol. 231: 2393-2401, 2016. © 2016 Wiley Periodicals, Inc.

Transdifferentiation of differentiated stem cells contributes to remyelination.

Evidence suggests that transdifferentiation of mesenchymal stem cells (MSCs) into various neuronal cells contributes to functional recovery after experimental spinal cord injury. Qiu et al. have recently published an exciting article in Stem Cell Research & Therapy demonstrating the transdifferentiation of already differentiated MSCs that contributes to remyelination of injured/regenerating axons, and thereby to functional recovery of spinal cord injured animals. The authors highlight the importance of interaction between neurotrophin-3 and tropomyosin receptor kinase C for the observed effects. This study provided important evidence that manipulation of rat bone marrow-derived MSCs before transplantation could enhance the therapeutic benefit of cell-based treatment.

Oriented growth and transdifferentiation of mesenchymal stem cells towards a Schwann cell fate on micropatterned substrates

While Schwann cells (SCs) have a significant role in peripheral nerve regeneration, their use in treatments has been limited because of lack of a readily available source. To address this issue, this study focused on the effect of guidance cues by employing micropatterned polymeric films to influence the alignment, morphology and transdifferentiation of bone marrow-derived rat mesenchymal stem cells (MSCs) towards a Schwann cell-like fate. Two different types of polymers, biocompatible polystyrene (PS) and biodegradable poly(lactic acid) (PLA) were used to fabricate patterned films. Percentages of transdifferentiated MSCs (tMSCs) immunolabeled with SC markers (α-S100β and α-p75(NTR)) were found to be similar on patterned versus smooth PS and PLA substrates. However, patterning had a significant effect on the alignment and elongation of the tMSCs. More than 80% of the tMSCs were oriented in the direction of microgrooves (0°-20°), while cells on the smooth substrates were randomly oriented. The aspect ratio [AR, ratio of length (in direction of microgrooves) and breadth (in direction perpendicular to microgrooves)] of the tMSCs on patterned substrates had a value of approximately five, as compared to cells on smooth substrates where the AR was one. Understanding responses to these cues invitro helps us in understanding the behavior and interaction of the cells with the 3D environment of the scaffolds, facilitating the application of these concepts to designing effective nerve guidance conduits for peripheral nerve regeneration.

598. Fusion of Mesenchymal Stem Cells Exclusively with “Degenerating” Cerebellar Neurons in Spinocerebellar Ataxia Type 1 Model Mice

Mesenchymal stem cells (MSCs) have the potential to migrate to damaged tissues where they participate in tissue repair. Previous studies suggest that intravenous or intracortical injections of MSCs results in the emergence of binucleated cerebellar Purkinje cells (PCs) containing a MSC-derived marker protein in mice suggestive of a fusion event. However, transdifferentiation of MSCs into PCs or transfer of a marker protein from a MSC to a PC cannot be completely ruled-out. Here we unequivocally showed a fusion of human fetal MSCs (hMSCs) with mouse PCs by combination of tetracycline-regulated system with Cre-dependent genetic inversion switch (flip-excision; FLEx). We performed intra-cerebellar injection of adeno-associated viral vectors expressing tetracycline transactivator (tTA) and Cre recombinase into either non-symptomatic (4 week-old) or clearly symptomatic (6 – 8 month-old) spinocerebellar ataxia type 1 (SCA1) mice. Two weeks after the treatment, the mice received injection of 50,000 geneticially-engineered hMSCs that expressed GFP only in the presence of Cre recombinase and tTA, which restricted GFP expression exclusively to cerebellar cells fused with hMSCs. We observed GFP-expressing PCs and interneurons in symptomatic, but not non-symptomatic, SCA1 mice as early as 2 weeks after the MSC injection. The frequency of GFP-expressing PCs did not increase when analysed at longer time points (≈23 weeks post hMSC grafting), suggesting that most hMSC fusion events occurred within 2 weeks of delivery. Using this model, we show conclusively that hMSC display a tendency to fuse with degenerating PC and interneurons, and not with normal neurons.

The multiple functional roles of mesenchymal stem cells in participating in treating liver diseases.

Mesenchymal stem cells (MSCs) are a group of stem cells derived from the mesodermal mesenchyme. MSCs can be obtained from a variety of tissues, including bone marrow, umbilical cord tissue, umbilical cord blood, peripheral blood and adipose tissue. Under certain conditions, MSCs can differentiate into many cell types both in vitro and in vivo, including hepatocytes. To date, four main strategies have been developed to induce the transdifferentiation of MSCs into hepatocytes: addition of chemical compounds and cytokines, genetic modification, adjustment of the micro-environment and alteration of the physical parameters used for culturing MSCs. Although the phenomenon of transdifferentiation of MSCs into hepatocytes has been described, the detailed mechanism is far from clear. Generally, the mechanism is a cascade reaction whereby stimulating factors activate cellular signalling pathways, which in turn promote the production of transcription factors, leading to hepatic gene expression. Because MSCs can give rise to hepatocytes, they are promising to be used as a new treatment for liver dysfunction or as a bridge to liver transplantation. Numerous studies have confirmed the therapeutic effects of MSCs on hepatic fibrosis, cirrhosis and other liver diseases, which may be related to the differentiation of MSCs into functional hepatocytes. In addition to transdifferentiation into hepatocytes, when MSCs are used to treat liver disease, they may also inhibit hepatocellular apoptosis and secrete various bioactive molecules to promote liver regeneration. In this review, the capacity and molecular mechanism of MSC transdifferentiation, and the therapeutic effects of MSCs on liver diseases are thoroughly discussed.

Abstract 17277: Myocardial Rescue by Mesenchymal Stem Cell via Tunneling Nanotube Formation

Objectives: Mesenchymal stem cell (MSC) shows promising therapeutic potentials for heart diseases in numerous animal studies and clinical trials. The cardiogenic transdifferentiation and paracrine factors delivery of MSCs are generally accepted mechanisms for myocardial rescue. Recent studies suggest that the rescue may also be achieved by direct delivery of subcellular organelles such as mitochondria. Tunneling nanotube (TNT) formation between MSCs and various damaged cell types has been observed both in vitro and in vivo for assisting organelle transfer. Based on our recent observation in a cell patterning-based in vitro assay, it is found that mitochondria are transferred from MSCs to neonatal cardiomyocytes (NCMs) through TNTs to enhance myocyte survival. Adequate investigation of hetero-paired TNTs is hampered by their random formation in standard cell culture and the difficulty of capturing them in vivo. Accordingly, a PDMS (polydimethylsiloxane) biochip-based coculture model was microfabricated to enable more consistent examination of TNT formation and mitochondrial transfer. Methods: Rat MSC (GFP tagged in green) and 3-day NCMs (w or w/0 treatment of 1 μg/ml lipopolysaccharide (LPS)) were introduced into a two-channel microfluidics-based biochip (Figure 1A) microfabricated with PDMS, and TNTs were guided to form in microchannels between the two cell types. The numbers of TNT formed between MSC and LPS treated or untreated NCM were counted per biochip after 24 hours coculturing. Then the sample was stained with annexin V to evaluate the cardiac stress of NCMs. Results and Discussion: It was observed that mitochondria were transferred unidirectionally from MSCs to NCMs via TNT (Figure 1B), irrespective of the TNT’s direction of formation. NCMs in stressed conditions triggered more TNT formation in red of annexin V staining with MSCs than the control (Figure 1C). It suggests that a rescue effect may be produced by TNT-mediated mitochondrial transfer.

Identification of regulatory factors for mesenchymal stem cell-derived salivary epithelial cells in a co-culture system.

Patients with Sjögren’s syndrome or head and neck cancer patients who have undergone radiation therapy suffer from severe dry mouth (xerostomia) due to salivary exocrine cell death. Regeneration of the salivary glands requires a better understanding of regulatory mechanisms by which stem cells differentiate into exocrine cells. In our study, bone marrow-derived mesenchymal stem cells were co-cultured with primary salivary epithelial cells from C57BL/6 mice. Co-cultured bone marrow-derived mesenchymal stem cells clearly resembled salivary epithelial cells, as confirmed by strong expression of salivary gland epithelial cell-specific markers, such as alpha-amylase, muscarinic type 3 receptor, aquaporin-5, and cytokeratin 19. To identify regulatory factors involved in this differentiation, transdifferentiated mesenchymal stem cells were analyzed temporarily by two-dimensional-gel-electrophoresis, which detected 58 protein spots (>1.5 fold change, p<0.05) that were further categorized into 12 temporal expression patterns. Of those proteins only induced in differentiated mesenchymal stem cells, ankryin-repeat-domain-containing-protein 56, high-mobility-group-protein 20B, and transcription factor E2a were selected as putative regulatory factors for mesenchymal stem cell transdifferentiation based on putative roles in salivary gland development. Induction of these molecules was confirmed by RT-PCR and western blotting on separate sets of co-cultured mesenchymal stem cells. In conclusion, our study is the first to identify differentially expressed proteins that are implicated in mesenchymal stem cell differentiation into salivary gland epithelial cells. Further investigation to elucidate regulatory roles of these three transcription factors in mesenchymal stem cell reprogramming will provide a critical foundation for a novel cell-based regenerative therapy for patients with xerostomia.

GW25-e1696 HDAC1 regulation of the transdifferentiation of mesenchymal stem cells to cardiomyocyte lineages in a myocardial microenvironment

GW25-e1696 HDAC1 regulation of the transdifferentiation of mesenchymal stem cells to cardiomyocyte lineages in a myocardial microenvironment

DNA topoisomerase IIβ as a molecular switch in neural differentiation of mesenchymal stem cells.

Two isoforms of DNA topoisomerase II (topo II) have been identified in mammalian cells, named topo IIα and topo IIβ. Topo IIα plays an essential role in segregation of daughter chromosomes and thus for cell proliferation in mammalian cells. Unlike its isozyme topo IIα, topo IIβ is greatly expressed upon terminal differentiation of neuronal cells. Although there have been accumulating evidence about the crucial role of topo IIβ in neural development through activation or repression of developmentally regulated genes at late stages of neuronal differentiation, there have been no reports that analyzed the roles of topo IIβ in the neural trans differentiation process of multipotent stem cells. Terminal differentiation of neurons and transdifferentiation of Mesenchymal Stem Cells (MSCs) are two distinct processes. Therefore, the functional significance of topo IIβ may also be different in these differentiation systems. MSC transdifferentiation into neuron-like cells represents an useful model to further validate the role of topo IIβ in neuronal differentiation. The aim of this study is to evaluate the subset of genes that are regulated in neural transdifferentiation of bone marrow-derived human MSCs (BM-hMSCs) in vitro and find genes related with topo IIβ. For this purpose, topo IIβ was silenced by specific small interfering RNAs in hMSCs and cells were induced to differentiate into neuron-like cells. Differentiation and silencing of topo IIβ were monitored by real-time cell analysis and also expressions of topo II isoforms were analyzed. Change in transcription patterns of genes upon topo IIβ silencing was identified by DNA microarray analysis, and apparently genes involved in regulation of several ion channels and transporters, vesicle function, and cell calcium metabolism were particularly affected by topo IIβ silencing suggesting that topoIIβ silencing can significantly alter the gene expression pattern of genes involved in variety of biological processes and signal transduction pathways including transcription, translation, cell trafficking, vesicle function, transport, cell morphology, neuron guidance, growth, polarity, and axonal growth. It appears that the deregulation of these pathways may contribute to clarify the further role of topo IIβ in neural differentiation.

Rewiring mesenchymal stem cell lineage specification by switching the biophysical microenvironment.

The propensity of stem cells to specify and commit to a particular lineage program is guided by dynamic biophysical and biochemical signals that are temporally regulated. However, most in vitro studies rely on “snapshots” of cell state under static conditions. Here we asked whether changing the biophysical aspects of the substrate could modulate the degree of mesenchymal stem cell (MSC) lineage specification. We chose to explore two diverse differentiation outcomes: MSC osteogenesis and trans-differentiation to neuron-like cells. MSCs were cultured on soft (~0.5 kPa) or stiff (~40 kPa) hydrogels followed by transfer to gels of the opposite stiffness. MSCs on soft gels express elevated neurogenesis markers while MSCs on stiff substrates express elevated osteogenesis markers. Transfer of MSCs from soft to stiff or stiff to soft substrates led to a switch in lineage specification. However, MSCs transferred from stiff to soft substrates maintained elevated osteogenesis markers, suggesting a degree of irreversible activation. Transferring MSCs to micropatterned substrates reveal geometric cues that further modulate lineage reversal. Taken together, this study demonstrates that MSCs remain susceptible to the biophysical properties of the extracellular matrix—even after several weeks of culture—and can redirect lineage specification in response to changes in the microenvironment.

Induction of ram bone marrow mesenchymal stem cells into germ cell lineage using transforming growth factor-β superfamily growth factors.

Several studies have proposed that in vitro generation of germ cells (GCs) from stem cells can be considered a future option for infertility treatment. Mesenchymal stem cells (MSCs) have the capability to differentiate into male GCs with the use of inducers such as retinoic acid. Transforming growth factor-beta 1 (TGFb1) has been shown to play important roles in male fertility and spermatogenesis. Bone morphogenic protein 4 (BMP4) and BMP8b are also involved in the derivation of primordial GCs (PGCs) from epiblast cells. Therefore, this study aims to determine whether TGFb1, BMP4 and BMP8b can initiate transdifferentiation of MSCs into GCs in vitro and to determine the type of changes that occur in the expression of GC-specific markers. In this study, we have divided passage-3 ram bone marrow (BM)-MSCs into three main groups (BMP4, BMP8b and TGFb1) which were separately treated with 10 ng/ml TGFb1, 100 ng/ml BMP4 and 100 ng/ml BMP8b for a period of 21 days. We have evaluated the ability of these groups to differentiate into GCs by assessing expressions of GC-specific markers with reverse transcription PCR (RT-PCR), quantitative RT-PCR (qRT-PCR), immunocytochemistry, morphological changes and alkaline phosphatase (ALP) activity. Our results showed that BMP4 and BMP8b induced PGCs properties in some BM-MSCs and TGFb1 formed spermatogonial stem cells (SSCs) and spermatogonia-like cells in BM-MSCs culture. The important results of this study provide the basis for additional studies to determine the exact mechanism of GCs differentiation and possibly solve the problem of infertility.

MSC-Derived HSCs Can Reconstitute Hematopoietic Function In Patients With Severe Aplastic Anemia

IntroductionNaturally-occurring regeneration of cells and tissues is generally involved in four working mechanisms such as directed differentiation, dedifferentiation, trans-differentiation and transdetermination. The better exploring of these mechanisms could be beneficial to develop clinical strategies for regenerative medicine and to reduce the likelihood of immune rejection and relevant complications Recently, “trans-determination” has attracted great controversy, mostly in regards to whether adult stem cells can colonize other tissues after transplantation. More importantly, how to generate large amounts of a particular stem cell type through a transdetermination process remained to be unsolved. Similarly, it is unclear whether mesenchymal stem cells (MSCs) can transdeterminate into hematopoietic stem cells (HSCs). MethodsMany technologies were used to validate the transdetermination of adipose-derived mesenchymal stem cells (AD-MSCs) into hematopoietic stem cells (HSCs) from different aspects. They include FACS analysis, PCR tests, immunostaining, expansion and repopulating assays, transplantation analysis and others, showing their in vivo and in vitro potentials for long-term self-renewal and differentiation into multi-lineages of blood cells. Moreover, these AD-HSCs can reconstitute hematopoietic function in six patients. ResultsWe report firstly here that a huge number of human AD-MSCs that are CD44+,CD29+, CD105+, CD166+,CD133-,CD34- could rapidly transdifferentiate into hematopoietic stem cells (CD49f+/CD133+/CD34+) and their descending blood cells in vitro, after transfected with two small RNAs. The sRNAs were high-effectively delivered into MSCs by a novel peptide means. These adipose-derived HSCs (AD-HSCs) could form different types of hematopoietic colonies as nature-occurring HSCs did. Upon the primary and secondary transplantation into sublethally or lethally irradiated mice, these MSC-HSCs engrafted and differentiated into all hematopoietic lineages such as erythrocytes, lymphocytes, myelocytes and thrombocytes. Furthermore, we demonstrated the first evidence that the transdetermination of MSCs was induced by acetylation of histone proteins and activation of many transcriptional factors. More excitingly, these MSC-derived HSCs can reconstitute hematopoietic function in six patients with severe aplastic anemia. Conclusionour findings identify the molecular mechanisms that regulate the directed transdifferentiation of MSCs toward HSCs, create a new source for individual HSC transplantation used for the treatment of blood diseases and cancers, and break the stalemate caused by bone marrow match and graft-versus-host disease. Disclosures:No relevant conflicts of interest to declare.