Tehran University Medical Journal

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MicroRNAs form a class of small non-coding RNA molecules. With only 21-23 nucleutide in length, they have an important role in gene expression. These molecules bind to their target mRNA molecules and repress the protein expression via mRNA degradation or blocking the translation machine of the cell. From the advent of molecular biology microRNA molecules were out of focus, however huge amount of studies in the past few years revealed a lot of facts about their nature. Nowadays around 1600 different microRNA are discovered in human, animals, plant and even viruses. In this review article the most recent data in the history, genes, expression and process of these molecules are introduced. Furthermore, the findings about diverse roles of these molecules in normal and abnormal conditions, cancer in particular, are shown. Finally, the differences to siRNA molecules and the prospect of microRNA have been explained.

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Background: MSCs have been isolated from a variety of mammals by the plastic adherence method. However, this method can be problematic due to the unwanted growth of hematopoietic cells and non-MSCs. The potential of MSCs to differentiate along multiple lineages is the key to the identification of stem cell populations in the absence of molecular markers. In the present study, we describe a homogeneous population of MSCs from mouse bone marrow isolated using an improved plastic adherence method that employs frequent medium change (FMC) at the initial hours of harvested bone marrow cell culture.
Methods: Balb/c mice were sacrificed and whole bone marrow cells were aspirated from the femur and tibia and then cultivated in six-well plates. After 3-4 hours of culture, old medium was removed and fresh medium was added. FMC was performed every eight hours over a 72 hour period. When primary cultures became nearly confluent, the first passage was performed. These cells were then used for further examination. To investigate their mesenchymal nature, the cells were allowed to differentiate into mesenchymal lineages and examined at each passage up to the tenth passage for surface antigens by flow cytometry.
Results: We achieved purified populations of fibroblast-like cells in the two weeks after culture initiation. The cells were capable of differentiating into osteocytes and adipocytes. Isolated MSCs were reactive to the CD44, Sca-1, and CD90 cell surface markers. MSCs were negative for hematopoietic surface markers such as CD34, CD11b, CD45, CD31, CD106, CD117 and CD135.
Conclusions: This protocol provides an efficient isolation of homogeneous populations of MSCs from mouse bone marrow.

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Normal 0 false false false EN-US X-NONE AR-SA MicrosoftInternetExplorer4 Background: Human bone marrow mesenchymal stem cells (hMSCs) can differentiate into several types of mesenchymal cells, including osteocytes, chondrocytes, and adipocytes, but can also differentiate into non-mesenchymal cells, such as neural cells, under appropriate experimental conditions. Until now, many protocols for inducing neuro-differentiation in MSCs in vitro have been reported. In this study, we induced differentiation into neural phenotype in the hMSCs population by new protocol. In this treatment, hMSCs could express neural markers more than other reports, associating with remarkable morphological modifications. 
Methods: The Bone marrow specimens were aspirated from the iliac crest of normal men. hMSCs were isolated and cultured in DMEM containing 15% FBS. Between 4-8 passages conversion of hMSCs into neurosphere-like structures and induction this cells to nerve precursors in the low-attachment plastic bacterial dishes with bFGF, EGF & RA were initiated. After seven days terminal neural differentiation was initiated by plating the cells on poly-L-ornithin and Laminin coated dishes. Cells were differentiated for 7-14 days. We used flowcytometry and immunocytochemistry analysis for assessment of specific neural stem cell markers in induced cells.
Results: Flowcytometery analysis showed that after induction, 90±2.52 percent of the cells will express neuronal marker Nestin and about 41±1 percent of the cells will express Tuj-1 and about 67±1.05 percent of the cells will express GFAP. Immunocytochemistry and morphologically modifications revealed the same results.
Conclusion: Results showed that hMSCs treatment with bFGF, EGF & RA the number of Tuj1 neurons. These data confirmed that hMSCs can exhibit neuronal differentiation potential in vitro, depending on the protocols of inducement.

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Background: Adipose-derived stem cells (ADSCs) have noticeable self-renewal ability and can differentiate into several cell lines such as adipocytes, osteoblasts, chondrocytes, and myocytes. Progesterone plays a significant role in the myelination of peripheral nerves. Regarding the role of progesterone on the myelination of peripheral nervous system, we evaluated its effects on the in-vitro expression of P0, S100 and Krox20 mRNA in adipose-derived stem cells. Methods: In this experimental study, rat adipose-derived stem cells were isolated from the inguinal region of the animals and were evaluated by flow cytometry before culture. In preinduction phase, the cells were sequentially treated with various factors such as β- mercaptoethanol and all-trans-retinoic acid, followed by different induction mixtures. The cells were divided into four groups including two control groups (receiving either fibroblast and platelet derived-growth factors, or fibroblast growth factor, platelet derived-growth factor, forskolin and heregulin) and two experimental groups (receiving either fibroblast growth factor, platelet derived-growth factor, forskolin and progesterone, or fibroblast growth factor, platelet derived-growth factor, heregulin and progesterone). Expression of Schwann cell markers, S-100, P0 and Krox20 mRNA, was determined by semi-quantitative RT-PCR. Results: ADSCs expressed CD90, CD73, and CD31 but showed lack of CD45, and VEGFR2 expression. After the induction stage, S-100, P0 and Krox20 mRNA were expressed in the progesterone receiving experimental groups, but expression of S-100 and Krox20 mRNA were less than the control group which was receiving forskolin and heregulin (P<0.0001). Conclusion: Progesterone can promote the in-vitro expression of S-100, P0, and Krox20 genes in adipose-derived stem cells

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Background: Cell-therapy provides a promising alternative for the treatment of type 1 diabetes. Monocytes which have a reprogramming or differentiation potential and are more available than any other types of stem cells, have been recognized as candidates for such investigations. The aim of the present study was to evaluate the differentiation potential of rat peripheral blood monocytes into insulin-producing cells by the use of rat pancreatic extract (2 days after a 60% pancreatectomy).

Methods: Rat peripheral blood monocytes were isolated and cultured. Adherent monocytes were induced to differentiate into programmable cells in RPMI supplemented by 10% FCS, &beta-mercaptoetanol, M-CSF and IL-3 for six days. The dedifferentiated cells were analyzed by invert microscopy. Cultures of Programmable Cells of Monocytic Origin (PCMOs) were continued in RPMI, containing 10% FBS, pancreatic extract and 5 mmol/L glucose for 15 days. The medium was replaced every three days. At the end of the protocol, insulin and c-peptide excreted by the differentiated cells were tested by radioimmunoassay on days 6, 14, and 21. In order to verify insulin production in the cells, dithizone-staining, which is a method for insulin identification, was employed.

Results: The results showed that the cells cultured in rat pancreatic extract secreted insulin and c-peptide relative to the control group. Dithizone-staining was positive in the aforesaid cells (P<0/05).

Conclusion: The results of the current study showed that pancreatic extract treatment can differentiate rat peripheral blood monocytes into insulin-producing cells which can be regarded as a potential source for the treatment of diabetes.

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Normal 0 false false false EN-US X-NONE AR-SA MicrosoftInternetExplorer4 Background: Aldehyde dehydrogenase 1 (ALDH1) is a marker of normal and malignant human mammary stem cells that has been reported to be associated with poor prognosis. Studies on the detection of ALDH1+ cells can help the treatment of patients with breast cancer. The aim of this study was to determine the activity of ALDH1 in breast cancer and its relationship with the pathological features of the tumors.
Methods:  ALDH1 activity was studied by immunohistochemistry in 121 paraffin-embedded histological samples of breast cancer patients from Department of Pathology of Milad Hospital, Tehran, Iran during 2006-2007. The relationship of ALDH1 with the pathological features of the tumors (size, grade, lymph node metastasis and vascular invasion) was also investigated.
Results:  Eighty-five percent of breast cancer samples expressed ALDH1 in their cytoplasm with a wide range of intensity (weak, moderate and strong), while 18 samples (14.9%) were completely negative. The majority of cases (97.1%) showed ALDH1 positivity in the stroma of tumors which varied from weak (2.9%) to strong (73.5%). ALDH1 H-score (ALDH1% × intensity) of tumor cells varied from 0 to 240 (mean= 80). ALDH1 H-score was ≤80 in 62 (51.2%) and >80 in 59 (48.8%) samples. There was no statistically significant relationship between ALDH1 H-score and age (P=0.358), tumor size (P=0.375), tumor grade (P=0.207), lymph node metastasis (P=0.125) or vascular invasion (P=0.190).
Conclusion: ALDH1 activity was demonstrated in 85.1% of breast cancer samples although its level of expression was not correlated with the pathologic features of breast tumors.

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Background: Bone Marrow Transplantations (BMT) are limited by low CD34+ cell counts in umbilical cord blood (UCB) and these cells need to be expanded for success in such procedures. To achieve this goal, ex vivo expansion of hematopoietic stem cells (HSCs) by enhancing their self-renewal activity on demineralized bone matrix (DBM) scaffold coated with mesenchymal progenitor cells (MPCs) and unrestricted somatic stem cells (USSCs) was recommended. TGF-b pathway is a key inhibitory factor for HSCs self-renewal. In this study ex vivo expansion and downregulation of TGF-b pathway were simultaneously performed.

Methods: USSC cells were isolated from UCB and then coated on DBM scaffold as a feeder layer. UCB CD34+ cells were isolated from UCB by magnetic activated cell sorting (MACS) method and were transfected by siRNA against TGFbR2 in two-dimensional (2D) and three-dimensional (3D) cultures by co-cultivation with USSC. TGFbR2 expression levels were evaluated by quantitative real-time PCR. Cell count and flow cytometry were performed and clonogenic activity was evaluated.

Results: Ex vivo expansion of CD34+ cells was significantly enhanced (41±0.7 folds) by TGFbR2 downregulation, especially in 2D than 3D cultures. Finally, 2D culture showed less TGFbR2 expression levels and higher increase in the percentage of CD34 markers by flow cytometry assay.

Conclusion: The 3D siRNA delivery system would be of lower efficiency in contrast to 2D settings where the cells have less freedom and are in more contact with the feeder layer.

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Background: Human embryonic stem cells (hESCs) are capable of self-renewal and large-scale expansion. They also have the capacity to differentiate into a variety of cell types including liver, cardiac and neuron cells. However, it is not yet clear whether hESCs can differentiate to hemangioblasts under in-vitro conditions. Hemangioblasts are bipotential progenitors that can generate hematopoietic lineages and endothelial cells. The aim of this study was to identify the potential of human Royan H5 embryonic stem cells in differentiating into hemangioblast cells.

Methods: HESCs were cultured at suspension system in DMEM/F12 supplemented with bFGF. 7-day old cells differentiated into blast cells under defined condition consisting of hematopoietic cytokines including BMP4, VEGF, etc. Blast cell markers kinase insert domain receptor (KDR), CD31, and CD34 were evaluated by flow cytometry and blast gene expressions (TAL-1, Runx-1 and CD34) were detected by qRT-PCR. Clonogenic assays were performed in semisolid medium by colony forming unit-assays.

Results: The hESCs (Royan H5) had the capacity of differentiating into hemangioblast cells. We could detect colonies that expressed 79%±12.5 KDR+, 5.6%±2.8 CD31+-CD34+ and 6%±2.12 KDR+-CD31+ on day 8 in the hESCs. Up-regulation of TAL-1, Runx-1 and CD34 occurred during hemangioblast commitment (P≤0.05 and P≤0.01, respectively). Moreover, hemangioblast cells generated mixed-type and endothelial-like colonies in semi-solid media.

Conclusion: Our results showed that hESCs (Royan H5) were able to differentiate into hemangioblasts under in-vitro conditions. The hemangioblasts had the potential to generate two non-adherent (Mixed-type) and adherent (endothelial-like) cell populations.

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Background: Currently, autologous and allogeneic adipose tissues represent a ubiqui-tous source of material for fat reconstructive therapies. However, these approaches are limited, and often accompanied by a 40-60% reduction in graft volume following transplantation, limited proliferative capacity of mature adipocytes for ex vivo expansion, and extensive adipocyte damage encountered when harvested with conventional liposuction techniques. Recently, cell-based approaches utilizing adipogenic progenitor cells for fat tissue engineering have been developed and were reported to promote both short-term in vivo adipogenesis and to repair defect sites. The aim of this study was to isolate stem cells from fat tissue than examine the growth of stem cells by invitro tests. Methods: For human adipose stem cell isolation (hASC), subcutaneous adipose tissue sites were obtained from female subjects undergoing elective procedures. Tissues were washed 3-4 times in phosphate buffered saline (PBS) and suspended in an equal volume of PBS supplemented with 1% FCS and 0.1% collagenase type I. The tissue was placed in an agitated water bath at 37 1C. The supernatant containing mature adipocytes, was aspirated. Portions of the SVF were suspended in DMEM medium. hASCs were selected based on their ability to adhere to tissue culture plastic and subsequently expanded to 75-90% confluence. Adipose stem cells were isolated and cultured on DMEM. To assess mesenchymal origin of stem cells we used flow-cytomery technique as well as differentiation to osteocyte and chondrocyte lines. Results: The nature of the mesenchymal cells was confirmed by flow -cytometry tech-niques, based on the expression of CD90, CD105, CD166, and lack of expression of hematopoietic markers of CD34, CD31, and CD45. The successful differentiation of our stem cells to osteocyte, chondrocyte had been showed by specific Alizarin-Red and Toluidine-blue staining of cells. Conclusion: Although we have not the results of in vivo tests to support in vivo adipo-genesis either alone or in combination with natural or synthetic matrix, the results showed that stem cells isolation from adipose tissue was successful, and we provided an environment for differentiation of stem cells.

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Background: Stem cells are applied in the treatment of wide range of diseases and can be separated from different tissues of the body. These cells can treat diseases by cytokine and growth factor secretion and also cell differentiation. Burn wound is a challenging problem of reconstructive surgery and stem cells may help wound healing process. We designed this study to evaluate the beneficial effect of fat derived stem cells for coverage of 3rd degree burn wound. Methods: This study was experimental and has been done in Burn Research Center of Iran University of Medical Sciences during January 2012 to April 2013. Thirty rats randomly divided to three equal groups. Inguinal fat of 10 rats (one group) were used for preparation of autologous adipose-derived mesenchymal stem cells. Acellular amnion was used as a scaffold for stem cell transfer. Each of the thirty rats had been exposed to a cm deep 3rd degree burn on back area. 24 hours after surgery, the wound was excised and it had been covered by three methods: conventional dressing in the first group, acellular amnion in the second group and acellular amnion seeded with adipose-derived stem cell in the third group. The rate of wound healing and pathologic characteristics was compared in all three groups. Results: Healing rate and decrease in wounds size was significantly better in acellular amnion seeded with adipose-derived stem cells compared with other two groups at 3rd and 15th days after surgery P<0.01. Also in histopathology examination, fibroplasia and neovascularization of wounds were significantly better in stem cells group than the other two groups P<0.001. Conclusion: Acellular amnion seeded with adipose-derived stem cell can result in faster wound healing and better histopathology characteristic. The amnion as a scaffold and the fat derived stem cells as healing accelerator are recommended for coverage of the 3rd degree burn wounds after excision and it may reduce the need for skin graft.

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Differentiated cells can change to embryonic stem cells by reprograming. Generation of induced pluripotent stem cells (iPSCs) has revolutionized the field of regenerative and personalized medicine. iPSCs can self-renew and differentiate into many cell types. iPSC cells offer a potentially unlimited source for targeted differentiation. Through the expression of a set of transcription factors, iPSCs can be generated from different kinds of embryonic and adult cells. This technology for the first time enabled the researchers to take differentiated cells from an individual, and convert them to another cell type of interest, which is particularly to that person. When the set of master transcription factors containing OCT4, SOX2, KLF4, and MYC is expressed ectopically in somatic cells, the transcriptional network is propelled to organize itself in such a way as to maintenance a pluripotent state. Since iPSCs are similar to Embryonic Stem Cell (ESC), they can be considered as sources for modeling different diseases. iPSCs which are induced from somatic cells of patient can be useful for screening and drugs selection, and also introduce treatment via grafting the cells. Although this technology has been successful in different fields, the tumorigenesis of viral vectors during induction of reprogramming is a major challenge. Nevertheless, iPSCs are valuable for clinical applications and research. By discovery of these cells many challenges related to the safety, efficacy, and bioethics of ESCs are solved. Pluripotency is defined in two aspect of functional and molecular, by which functional regards the capacity of cell is generate three kinds of embryonic layers and germ line, and molecular aspect regards the identifying of molecules and genes that support functional features. Identification of these genes has been placed at the center of fields related to development and stem cell research. In this review, we discuss the process of generation of these cells, as well as required genes and factors for pluripotency, and also current progress in generation of iPSCs utilizing tens of reliable and new studies.

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Embryonic stem cells are pluripotent stem cells which have the ability to indefinitely self-renew and differentiate into all differentiated cells of the body. Regarding their two main properties (unlimited self-renewal and multi-lineage differentiation), these cells have various biomedical applications in basic research and cell based therapy. Because the transplantation of differentiated cells that are derived from embryonic stem cells is allogenic, they face the problem of immune rejection following the transplantation of embryonic stem cell-derived cells into patients. In 2006, researchers from Japan reported the derivation of a new type of pluripotent stem cells which could overcome the problem of immune rejection that is associated with the application of embryonic stem cells. They designated these cells as induced pluripotent stem (iPS) cells, because their production was ‘induced’ from differentiated somatic cells using a combination of four embryonic stem cell-associated transcription factors. Importantly, these pluripotent stem cells exhibit all the key features of embryonic stem cells including unlimited self-renewal and multi-lineage differentiation potential, and can pass the most stringent test of pluripotency which is known as the tetraploid (4n) complementation. Hence, in addition to bypassing the problem of immune rejection, iPS cells have all of the potential applications of embryonic stem cells, including in developmental studies, toxicology research, drug discovery and disease modeling. Also, considering that they could be generated from patient’s own cells, iPS cells hold great promise in the future of patient-specific cell replacement therapies using pluripotent stem cells. In this review article, we will present a comprehensive review on the how and why of the generation of iPS cell from somatic cells of the body and discuss how they should be characterized in terms of morphologically, pluripotent stem cell behavior, and the molecular signature. In addition, their medical applications as well as some of the considerations and future challenges in their use will be discussed.

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Background: About 15% of couples have fertility problems and male factor in fertility accounts for half of the cases. In vitro generation of germ cells introduces a novel approach to male infertility and provides an effective system in gene tracking studies, however many aspects of this process have remained unclear. We aimed to promote mouse embryonic stem cells (mESCs) differentiation into germ cells and evaluate its effectiveness with tracking the expression of the Testis specific 10 (Tsga10) during this process. Methods: This is an in vitro study that was performed in department of Medical Genetics in Tehran University of Medical Sciences from February 2012 to March 2013. Mouse embryonic stem cells were cultured on mouse embryonic fibroblast as feeder layer. Then mESCs were differentiated into germ cells in the presence of Retinoic Acid. Based on developmental schedule of the postnatal testis, samples were taken on the 7th, 12th and 25th days of the culture and were subjected to expression analysis of a panel of germ cell specific genes (Stra8 as pre-meiotic, Dazl and Sycp3‌ as meiotic and Protamin1 and Spata19 as Post-meiotic). Expression of Testis Specific Gene 10 (Tsga10) at RNA and protein levels was then analyzed. Results: It was shown that transition of embryonic stem cells from mitosis to meiosis occurred between 7th and 12th days of mESC culture and post-meiotic gene expression did not occur until 25th day of the culture. Results showed low level of Tsga10 expression in undifferentiated stem cells. During transition from meiotic to post-meiotic phase, Tsga10 expression increased in 6.6 folds. This finding is in concordance with in vivo changes during transition from pre-pubertal to pubertal stage. Localization of processed and unprocessed form of the related protein was similar to those in vivo as well. Conclusion: Expression pattern of Tsga10, as a gene with critical function in spermatogenesis, is similar during in vitro and in vivo germ cell generation. The results suggest that in vitro derived germ cells could be a trusted model to study genes behavior during spermatogenesis.

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Background: Hematopoietic stem cell transplantation (HSCT) is a therapeutic approach in treatment of hematologic malignancies and incompatibility of bone marrow. Umbilical cord blood (UCB) known as an alternative for hematopoietic stem/ progenitor cells (HPSC) for in allogenic transplantation. The main hindrance in application of HPSC derived from umbilical cord blood is the low volume of collected samples. So, ex vivo expansion of HPSCs is the useful approach to overcome this restriction. Synthetic biomaterials such as nanofibers is used to produce synthetic niches. The aim of this study was the ex vivo expansion of hematopoietic stem cells on biocompatible nanofiber scaffolds. Methods: This study was done at Tarbiat Modares University from November 2012 to June 2013 and was a research study. Umbilical cord blood CD133+ hematopoietic stem cells were separated using MidiMacs (positive selection) system by means of monocolonal antibody (microbeads) CD133. Flow cytometry was used to assess the purity of cells. Cell culture was done on plate (2 Dimensional) and fibronectin conjougated polyether sulfone nanofiber scaffold (3 Dimensional). Colony assay test was used to asses the ability of colonization of cells. Results: Cell count analysis revealed the expansion of hematopoietic stem cells in cell culture plate (2D environment) and on nanofiber scaffold (3D environment) after 2 weeks. Expansion of cells in 2D environment was greater than 3D condition. Colony assay test revealed that the colonization ability of cells decreased after 2 weeks, but this decrease was lower in scaffold culture than plate culture. Conclusion: This study demonstrated that umbilical cord blood CD133+ hematopoietic stem cells can expand on fibronectin conjugated polyether sulfone scaffold and we can use this system for expanding of cells in vitro situation.

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Background: Stem cells represent an ideal cell source for application in tissue engineering and regenerative medicine due to their ability to proliferate and differentiate to a wide variety of cell lineages. With recent development of medical sciences and tissue engineering, usage of adipose-derived mesenchymal stem cells, their culture and differentiation on suitable scaffolds are considered as a successful clinical and research strategy. One of the most crucial factors in a successful tissue engineering technique is to choose an appropriate scaffold which allow cell migration transferring of bioactive factors as well as providing optimal growth environment for stem cells. In this study, the ability of two scaffolds is investigated as a suitable environment for the proliferation and differentiation of adipose-derived mesenchymal stem cells. Methods: This is an in vitro study that was performed in Laboratory of Stem Cell in Academic Center for Education, Culture and Research, Qom province from April 2013 to February 2014. In this study, two scaffolds including fibrin glue and alginate were prepared as two separate groups and after isolating mesenchymal stem cells from adipose tissue and adequate proliferation, they were seeded into each scaffold in chondrogenic medium. After 14 days, the evaluation of viability and gene expression of collagen II and I, SOX9 and aggrecan were done by MTT (3-{4,5-dimethylthiazol-2yl}-2,5-diphenyl-2H tetrazolium bromide) assay and real-time PCR technique respectively. Also, cartilaginous tissue formation on scaffolds was evaluated by histological analysis. Results: According to the obtained results, the fibrin glue scaffold showed significant difference in terms of viability in comparison to alginate scaffold in chondrocyte differentiating medium (P< 0.05). Also the results of real-time PCR analysis showed that the fibrin glue scaffold express cartilage specific genes at a higher level than alginate scaffold. Conclusion: The use of natural fibrin glue scaffold can be considered as a suitable environment for proliferation and differentiation of adipose-derived mesenchymal stem cells in cartilage tissue engineering.

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Background: Allergic Asthma is an inflammatory disease of the respiratory system that is well known by increased inflammatory cells in the airways and causes difficulty in respiration. The prevalence of allergic asthma is increasing worldwide, and it has become a significant cause of health challenge especially in developed countries. Inhaled β2-agonists and Inhaled or oral corticosteroids are common medications for treating the disease, but they cannot be used for long periods of time because of frequently occurring side effects and they can’t change the main pathogenesis of the problem. Deficiency in regulatory system against inflammation could be an important factor in allergic asthma. Mesenchymal stem cells (MSCs) have potential of cellular immunosuppressive therapy of inflammatory disorders. The aim of present study was to evaluate the effects of MSC therapy on mechanisms of allergic asthma in mice model. Methods: This experimental study was conducted from August 2014 to March 2015. The animals were housed and maintained in Biotechnology Center of Urmia University, Iran. Mice were sensitized by intra-peritoneal injection of ovalbumin (OVA) and aluminum hydroxide emulsion and then were challenged intra-nasally with OVA. Before allergen challenge on day 14, experimental mice received tail vein injection of MSCs in PBS. Regulatory T cells of spleen, cytokines and IgE analysis were carried out using lungs wash as well as serum samples. Results: Our results showed that MSCs significantly reduced total cells and eosinophilia, serum OVA-specific IgE concentration in OVA-sensitized and challenged mice. Also results showed that MSCs markedly inhibited expressions of Th2 cytokines and elevated levels of Treg cells and Treg cytokines. Conclusion: In the present study, we demonstrated the inhibitory effect of MSCs on airway inflammation using mice model of allergic asthma. The mice were sensitized with OVA and compared to the results of dexamethasone administration. Our results demonstrated that administration of MSCs could be used as a potential therapeutic approach for the allergic asthma.

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Background: Spermatogenesis is a complex and highly organized process of proliferation and differentiation of spermatogonial stem cells. Spermatogonial stem cells (SSCs) as a unique stem cell have the potential to self-renewal, differentiation and transmit genetic information to the next generation and play a vital role in maintaining fertility. Sertoli cells as the only somatic cells within the seminiferous epithelium play central roles in the formation of niche and balance between self-renewal and differentiation by secrete many growth factors. Given the importance and widespread use of SSCs, particularly in the treatment of infertility, the aim of this study was to create an optimal environment for the proliferation of SSCs. So we decided to study of undifferentiated (ID4) and differentiated (c-Kit) gene expression in SSCs followed by co-culture with Sertoli cells for a one-month.

Methods: This experimental study was conducted from November 2013 to December 2014 in Department of Anatomy, School of Medicine, Tehran University of Medical Sciences, on immature NMRI mouse (6-3 days old). Initially, Sertoli cells and SSCs were isolated from neonates mouse testes during the two-step enzymatic digestion characteristics Sertoli cells with vimentin marker and SSCs with promyelocytic leukemia zinc-finger (PLZF) marker were confirmed. Then SSCs were cultured in two groups: co-culture with Sertoli and without co-culture (control). Undifferentiated (ID4) and differentiation (c-Kit) gene expression were evaluated by Real-time PCR technique.

Results: Spermatogonial stem cells purity was obtained 66.91% by flow cytometry. The relative expression levels of gene ID4 in co-culture group at the end of each week, compared to the control group showed a significant increase (P<0.05). While the expression of this gene significantly decreased in each group over time (P<0.05). The results of the comparison of the relative expression of c-Kit gene in co-culture group are indicated significant decrease than the control group at the end of each week (P<0.05). In addition, this gene expression was showed significant increase in each group individually over time (P<0.05) ID4 gene expression showed a significant (P<0.05) increase toward the control group, while in the expression of c-Kit was observed a significant (P<0.05) decrease compared with the control group at the end of each week.

Conclusion: According to the results of this study, co-culture with Sertoli cells maintains SSCs in the prolifration stage for long-term, so can be used to optimize the culture medium at the clinic.

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Stem cells are undifferentiated and multi pluripotent cells which can differentiate into a variety of mature cells and tissues such as nervous tissue, muscle tissue, epithelial tissue, skeletal tissue and etc. Stem cells from all different source have three unique features: 1) Proliferative capability: Stem cells are capable of self dividing and self renewing for long periods or more than six months at least that called immortalization. 2) Undifferentiated nature: It’s considered as one of the essential characteristics of stem cell, so it doesn't have any tissue-specific construction. 3) Differentiation to the different cells from all organs: This ability can Induced by tissue specific transcription factors. Because of that, they are so important in prevention and treatment of human disease. Depending on the sources from which they derive, they have different types which can be used to produce special cells and tissues. The most significant types of stem cells are; embryonic stem cells (ESCs) which are derived from embryos, adult stem cells (ASCs) which are derived from differentiated cells in a specific tissue, induced pluripotent stem cells (iPSs) which are produced from adult differentiated cells that have been genetically reprogrammed to act resemble to an embryonic stem cell and cord blood stem cells which contains haematopoietic stem cells and derived from the umbilical cord after gestation. By providing a medium containing of special growth factor, it is possible to orientated stem cell differentiation pathway and gained certain cells from them. The important uses of stem cells includes damaged heart tissue cells improvements and bone tissue repairing, cancer treatment, damaged neurological and spinal tissue repairing, improving burns and injuries and the treatment of diabetes, infertility and spermatogenesis dysfunction. Furthermore, the application of them in gene therapy is an important issue in the modern medicine science due to the role of them in transferring gene into different cells. Today, this method have had considerable progress in the treatment of many disease. In this review study, some aspect of stem cells like types and characteristic, origin, derivation techniques, storage conditions and differentiation to target tissues, current clinical usage and their therapeutic capabilities will be discussed.

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It was assumed that the loss of cardiomyocytes is irreversible. The main goal is to develop widely available and clinically applicable treatments for heart diseases. The several studies have showed that the use of stem cells can improve complicacies such as cardiovascular diseases. Stem cells have a potential benefit of the self-renewal and cell differentiation into the cell types that can play an important role in the organogenesis and the embryonic development. In a lifetime, the heart muscle has a population of cardiac stem cells (CSCs) in which a dramatically increase after cardiovascular damages. So far, seven types of CSCs have been discovered with the different molecular phenotype and the cell differentiation potential. In this regard, the proliferation and the differentiation increase of CSCs in the cardiac ischemic areas can be a key factor to improve heart complicacies. Paracrine and/or autocrine factors, the extracellular matrix and the genetic mediators including microRNA can control the function of CSCs. It has clearly been understood that the factors mentioned previously have the ability to improve these complicacies. The differentiation, the survival and the self-renewal of CSCs are largely under the control of factors in the heart microenvironment. Several studies showed that the cytokines and the growth factors play the important role in the proliferation and the migration of CSCs. Taking advantage of these factors together CSCs to repair damaged heart can enhance this method efficiency. This review will discuss the different kinds of CSCs, their molecular phenotype and cardiac regeneration potential in order to improve cardiovascular diseases. It seems that CSCs-based therapy is emerging as a novel approach for myocardial repair over conventional cardiovascular therapies. Therefore, understanding the new aspects on the molecular mechanisms and the signaling pathways involving CSCs is critical for the development of the therapeutic strategies in cardiac patients that would be valuable for researchers in both fields of molecular and clinical cardiology.

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Background: Telomerase as an enzyme with reverse transcriptase activity has an essential role in telomere maintenance by adding a telomere repeat sequence to the 3' end of chromosome and is important for regulating of many processes in embryonic development including cell proliferation and differentiation. Human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) with a self-renewal capacity are cells that can differentiate into various germ layer derivatives including neural cells and cardiomyocytes, and undergo biological changes during long-term cultivation. Hence, the passage number in which the cells expanded seems to be very important for proliferating and differentiating. This study was aimed at investigating the relationship between the telomerase activity and the growth rate of (hUC-MSCs) at different passages.

Methods: This experimental study was performed in Ardabil University of Medical Sciences, Iran, from March 2014 to December 2014. The umbilical cord samples were obtained from full-term neonate hospitalized in Alavi’s Hospital in Ardabil under sterile conditions. The umbilical vessels were clear off and the small pieces of the umbilical cord were cultured in Dulbecco's modified eagle's medium (DMEM) supplemented with 20% fetal bovine serum (FBS). Then, the hUC-MSCs were harvested from passage one to three to calculate the population doubling time (PDT) and extract proteins by using CHAPS lysis buffer. Finally, the telomerase activity of the cells at different passages was measured by telomeric repeat amplification protocol (TRAP) and qRT-TRAP assays.

Results: The hUC-MSCs population doubling time at passage from 1 to 3 were calculated as the average of 54.68±1.92, 55.03±1.71 and 69.41±2.54 hours, respectively, suggesting the higher cell passage number, the more extended PDT. The threshold cycles (CTs) for the telomerase activity also showed 30.58±0.51, 27.24±0.74 and 32.13±0.75 for the cell passage from one to three, respectively, representing the significant increasing in telomerase activity at passage two compared with the other passages (P= 0.021).

Conclusion: Analysis of the growth curve, PDT determination and measurement of telomerase activity of the human umbilical cord-derived mesenchymal stem cells showed that the long-term cell culture can affect on the cell proliferation and the telomerase activity.