The expression of anti-aging protein Klotho is increased during neural differentiation of bone marrow-derived mesenchymal stem cells

Klotho, as an antiaging protein, is involved in the maintenance and differentiation of neuronal or glial cells and, therefore, has been noticed as a potential therapeutic target for neurodegenerative disorders. Expression of Klotho has been examined in different cells and organs, however, our information about the developmental pattern of this protein during differentiation of mesenchymal stem cells (MSCs) into neuron-like cells is limited. In this study, we conducted neural differentiation of mouse bone marrow-derived-MSCs and monitored the expression of Klotho together with selected neuron-specific genes at messenger RNA (mRNA) on days 7 and 14 of differentiation using quantitative real-time PCR. In addition, Klotho status at protein level was evaluated by immunocytochemistry. The results showed a significant change in the morphology of MSCs towards neuron-like cells. These changes were observed with progressive growth and formation of cell connections towards the formation of a chain of neuron-like cells which occurred in the second week of differentiation. Morphological changes were associated with a significant increase in the expression of neuron-specific genes like pax-6, neuN and, neurofilaments (NfL). Likewise, there was an increased expression of Klotho mRNA, and accumulation of Klotho protein in neuronal cell bodies, during the cellular differentiation of MSCs. These findings provided new evidence that neuronal differentiation from the MSCs is associated with increased expression of Klotho. These data may provide insight into the importance of Klotho protein in stem cell differentiation and regeneration in response to cell death in the central nervous system.

MiR-146a suppresses the expression of CXCR4 and alters survival, proliferation and migration rate in colorectal cancer cells

CXCR4 plays an important role in colorectal cancer (CRC) development and metastasis. Some previous studies have indicated CXCR4 as a therapeutic target in cancer. CXCR4 is known as a direct target of miR-146a. The present study aimed to investigate how exogenous induction of miR-146a affects CXCR4 gene and protein expression and also proliferation, apoptosis and migration of CRC cells. Transfection of Caco-2 and SW480 cells by a synthetic miR-146a mimic led to downregulation of CXCR4 expression at both gene and protein levels. It also downregulated expression of several miR-146a targets, including GSK3B, IRAK1, TRAF6, AKT2, SMAD4, EGFR and NFKB1, mostly in SW480 cells. Overexpression of miR-146a resulted in a partial cell cycle arrest in the both cell lines, while the apoptotic rate was also decreased. In regards to epithelial-mesenchymal transition factors, VIM was downregulated in the both cell lines, but SNAI1 was upregulated in Caco-2 cells. The wound closure assay showed a reduction in cell migration in SW480 cells, but an opposite effect was detected in Caco-2 cells following transfection with miR-146a mimic. Therefore, our results are indicating that overexpression of miR-146a, despite downregulation of oncogenic CXCR4, may not lead to a universal tumor suppressive effect in all CRC cells, and this is possibly due to differences in miR-146a effects on signaling pathways in each cell type. Selection of miR-146a for tumor suppression requires enough details regarding the signaling profile of cancer cells otherwise it may produce unexpected outcome.

Reprogramming By Cytosolic Extract of Human Embryonic Stem Cells Improves Dopaminergic Differentiation Potential of Human Adipose Tissue-Derived Stem Cells

Introduction:

The extract of pluripotent stem cells induces dedifferentiation of somatic cells with restricted plasticity.

Methods:

In this study, we used the extract of human embryonic stem cells (hESC) to dedifferentiate adipose tissue-derived stem cells (ADSCs) and examined the impact of this reprogramming event on the dopaminergic differentiation of the cells. For this purpose, cytoplasmic extract of ESCs was prepared by repeated freezing and thawing cycles. The plasma membrane of hADSCs was reversibly permeabilized by streptolysin O (SLO), exposed to hESC extract, and resealed by a CaCl2-containing medium.

Results:

As revealed by qPCR analysis, expression of OCT4, SOX2, NANOG, LIN28A, and KLF4 mRNAs were downregulated in the ADSCs one week after extract incubation, while all mRNAs except for KLF4 were upregulated at the end of the second week. For dopaminergic differentiation, control and reprogrammed ADSCs were induced by a serum-free neurobasal medium containing B27 and a cocktail of sonic hedgehog (SHH), basic fibroblast growth factor (bFGF), fibroblastic growth factor 8 (FGF8), and brain-derived neurotrophic factor (BDNF) for 12 days. After differentiation, the expression levels of some neuronal and dopaminergic-related genes, including PAX6, NESTIN, NEFL, GLI1, LMXB1, EN1, NURR1, and TH, significantly increased in the reprogrammed ADSCs compared to the control group. On the whole, two weeks after reprogramming by ESC extract, ADSCs showed an improved dopaminergic differentiation potential.

Conclusion:

These findings suggest that the cytoplasmic extract of hESCs contains some regulatory factors which induce the expression of pluripotency-associated markers in somatic cells and that the exposure to ESC extract may serve as a simple and rapid strategy to enhance the plasticity of somatic stem cells for cell replacement therapy purposes.

Highlights

Plain Language Summary

The extract of pluripotent stem cells induces dedifferentiation of somatic cells with restricted plasticity. In this study, we used the extract of hESC to dedifferentiate ADSCs and examined the impact of this reprogramming event on the dopaminergic differentiation of the cells. Cytoplasmic extract of ESCs was prepared by repeated freezing and thawing cycles. These cells express several neuron-specific genes, secrete several factors associated with neuroprotection, and exhibit differentiation into neural and glial cells in vitro. In recent years, several studies have documented dopaminergic differentiation of hADSCs.

Cardiac Differentiation of Adipose Tissue-Derived Stem Cells Is Driven by BMP4 and bFGF but Counteracted by 5-Azacytidine and Valproic Acid

Objective

Bone morphogenetic protein 4 (BMP4) and basic fibroblast growth factor (bFGF) play important roles in embryonic heart development. Also, two epigenetic modifying molecules, 5'-azacytidine (5'-Aza) and valproic acid (VPA) induce cardiomyogenesis in the infarcted heart. In this study, we first evaluated the role of BMP4 and bFGF in cardiac trans-differentiation and then the effectiveness of 5´-Aza and VPA in reprogramming and cardiac differentiation of human adipose tissue-derived stem cells (ADSCs).

Materials and Methods

In this experimental study, human ADSCs were isolated by collagenase I digestion. For cardiac differentiation, third to fifth-passaged ADSCs were treated with BMP4 alone or a combination of BMP4 and bFGF with or without 5'-Aza and VPA pre-treatment. After 21 days, the expression of cardiac-specific markers was evaluated by reverse transcription polymerase chain reaction (RT-PCR), quantitative real-time PCR, immunocytochemistry, flow cytometry and western blot analyses.

Results

BMP4 and more prominently a combination of BMP4 and bFGF induced cardiac differentiation of human ADSCs. Epigenetic modification of the ADSCs by 5'-Aza and VPA significantly upregulated the expression of OCT4A, SOX2, NANOG, Brachyury/T and GATA4 but downregulated GSC and NES mRNAs. Furthermore, pre-treatment with 5'-Aza and VPA upregulated the expression of TBX5, ANF, CX43 and CXCR4 mRNAs in three-week differentiated ADSCs but downregulated the expression of some cardiac-specific genes and decreased the population of cardiac troponin I-expressing cells.

Conclusion

Our findings demonstrated the inductive role of BMP4 and especially BMP4 and bFGF combination in cardiac trans-differentiation of human ADSCs. Treatment with 5'-Aza and VPA reprogrammed ADSCs toward a more pluripotent state and increased tendency of the ADSCs for mesodermal differentiation. Although pre-treatment with 5'-Aza and VPA counteracted the cardiogenic effects of BMP4 and bFGF, it may be in favor of migration, engraftment and survival of the ADSCs after transplantation.

Repression of TGF-β Signaling in Breast Cancer Cells by miR-302/367 Cluster

Objective

Epigenetic alterations of the malignantly transformed cells have increasingly been regarded as an important event in the carcinogenic development. Induction of some miRNAs such as miR-302/367 cluster has been shown to induce reprogramming of breast cancer cells and exert a tumor suppressive role by induction of mesenchymal to epithelial transition, apoptosis and a lower proliferation rate. Here, we aimed to investigate the impact of miR-302/367 overexpression on transforming growth factor-beta (TGF-β) signaling and how this may contribute to tumor suppressive effects of miR-302/367 cluster.

Materials and Methods

In this experimental study, MDA-MB-231 and SK-BR-3 breast cancer cells were cultured and transfected with miR-302/367 expressing lentivector. The impact of miR-302/367 overexpression on several mediators of TGF-β signaling and cell cycle was assessed by quantitative real-time polymerase chain reaction (qPCR) and flow cytometry.

Results

Ectopic expression of miR-302/367 cluster downregulated expression of some downstream elements of TGF-β pathway in MDA-MB-231 and SK-BR-3 breast cancer cell lines. Overexpression of miR-302/367 cluster inhibited proliferation of the breast cancer cells by suppressing the S-phase of cell cycle which was in accordance with inhibition of TGF-β pathway.

Conclusion

TGF-β signaling is one of the key pathways in tumor progression and a general suppression of TGF-β mediators by the pleiotropically acting miR-302/367 cluster may be one of the important reasons for its anti-tumor effects in breast cancer cells.

Directed differentiation of human adipose tissue-derived stem cells to dopaminergic neurons in low-serum and serum-free conditions

Directing the fate of mesenchymal stem cells (MSCs) to dopaminergic neurons has great importance in both biomedical studies and cell therapy of Parkinson's disease. We recently generated dopamine-secreting cells from human adipose tissue-derived stem cells (hADSCs) by exposing the cells to a growth factor cocktail composed of SHH, bFGF, FGF8 and BDNF in low-serum condition. In the current study, we induced the cells by the same dopaminergic inducing cocktail in serum-free B27-supplemented Neurobasal medium. ADSCs differentiated in both conditions expressed several neuronal and dopaminergic markers. However, there were higher gene expression levels under the serum-free condition. Higher levels of TUJ1 and TH proteins were also detected in the cells exposed to the dopaminergic-inducing cocktail under serum-free Neurobasal condition. TH protein was expressed in about 28% and 60% of the cells differentiated in the low-serum and serum-free Neurobasal media, respectively. Moreover, the cells exposed to the dopaminergic-inducing cocktail in the serum-free Neurobasal condition released a more significant amount of dopamine in response to KCl-induced depolarization. Altogether, these findings show a greater efficiency of the serum-free Neurobasal condition for growth factor-directed differentiation of hADSCs to functional dopamine-secreting cells which may be valuable for transplantation therapy of Parkinson's disease in future.

Tumor suppressive effects of the pleiotropically acting miR-195 in colorectal cancer cells

Downregulation of miR-195 in colorectal cancer tissues has been reported in several studies. We investigated the impact exogenous induction of mature miR-195-5p on some malignant features of human colorectal cancer cells. Caco-2 and SW480 human colon cancer cell lines were transfected with a synthetic miR-195-5p mimic. Exogenous induction of miR-195-5p suppressed multiple mediators of invasion and angiogenesis in colorectal cancer cells and increased the apoptotic cell population in both cell lines. Also, migration of both cell lines was significantly compromised after miR-195 transfection. Our results are indicating a strong tumor suppressive role for miR-195 in human colorectal cancer.

Priming with oxytocin and relaxin improves cardiac differentiation of adipose tissue-derived stem cells

Previous studies have identified the heart as a source and a target tissue for oxytocin and relaxin hormones. These hormones play important roles in the regulation of cardiovascular function and repair of ischemic heart injury. In the current study, we examined the impact of oxytocin and relaxin on the development of cardiomyocytes from mesenchymal stem cells. For this purpose, mouse adipose tissue-derived stem cells (ADSCs) were treated with different concentrations of oxytocin or relaxin for 4 days. Three weeks after initiation of cardiac induction, differentiated ADSCs expressed cardiac-specific genes, Gata4, Mef2c, Nkx2.5, Tbx5, α- and β-Mhc, Mlc2v, Mlc2a and Anp, and cardiac proteins including connexin 43, desmin and α-actinin. 10 ^-7 M oxytocin and 50 ng/mL relaxin induced the maximum upregulation in the expression of cardiac markers. A combination of oxytocin and relaxin induced cardiomyocyte differentiation more potently than the individual factors. In our experiment, oxytocin-relaxin combination increased the population of cardiac troponin I-expressing cells to 6.84% as compared with 2.36% for the untreated ADSCs, 3.7% for oxytocin treatment and 3.41% for relaxin treatment groups. In summary, the results of this study indicated that oxytocin and relaxin hormones individually and in combination can improve cardiac differentiation of ADSCs, and treatment of the ADSCs and possibly other mesenchymal stem cells with these hormones may enhance their cardiogenic differentiation and survival after transplantation into the ischemic heart tissue.

Down-regulation of the non-coding RNA H19 and its derived miR-675 is concomitant with up-regulation of insulin-like growth factor receptor type 1 during neural-like differentiation of human bone marrow mesenchymal stem cells

The differentiation of human bone marrow mesenchymal stem cells (BMSCs) into specific lineages offers new opportunities to use the therapeutic efficiency of these pluripotent cells in regenerative medicine. Multiple lines of evidence have revealed that non-coding RNAs play major roles in the differentiation of BMSCs into neural cells. Here, we applied a cocktail of neural inducing factors (NIFs) to differentiate BMSCs into neural-like cells. Our data demonstrated that during neurogenic induction, BMSCs obtained a neuron-like morphology. Also, the results of gene expression analysis by qRT-PCR showed progressively increasing expression levels of neuron-specific enolase (NSE) as well as microtubule-associated protein 2 (MAP-2) and immunocytochemical staining detected the expression of these neuron-specific markers along differentiated BMSC bodies and cytoplasmic processes, confirming the differentiation of BMSCs into neuronal lineages. We also compared differences in the expression levels of the long non-coding RNA (lncRNA) H19 and H19-derived miR-675 between undifferentiated and neurally differentiated BMSCs and found that during neural differentiation down-regulation of the lncRNA H19/miR-675 axis is concomitant with up-regulation of insulin-like growth factor type-1 (IGF-1R), a well-established target of miR-675 involved in neurogenesis. The findings of the current study provide support for the hypothesis that miR-675 may confer functionality to H19, suggesting a key role for this miRNA in the neural differentiation of BSMCs. However, further investigation is required to gain deeper insights into the biological roles of this miRNA in the complex process of neurogenesis.

Extract of mouse embryonic stem cells induces the expression of pluripotency genes in human adipose tissue-derived stem cells

Objective(s):

In some previous studies, the extract of embryonic carcinoma cells (ECCs) and embryonic stem cells (ESCs) have been used to reprogram somatic cells to more dedifferentiated state. The aim of this study was to investigate the effect of mouse ESCs extract on the expression of some pluripotency markers in human adipose tissue-derived stem cells (ADSCs).

Materials and Methods:

Human ADSCs were isolated from subcutaneous abdominal adipose tissue and characterized by flow cytometric analysis for the expression of some mesenchymal stem cell markers and adipogenic and osteogenic differentiation. Frequent freeze-thaw technique was used to prepare cytoplasmic extract of ESCs. Plasma membranes of the ADSCs were reversibly permeabilized by streptolysin-O (SLO). Then the permeabilized ADSCs were incubated with the ESC extract and cultured in resealing medium. After reprogramming, the expression of some pluripotency genes was evaluated by RT-PCR and quantitative real-time PCR (qPCR) analyses.

Results:

Third-passaged ADSCs showed a fibroblast-like morphology and expressed mesenchymal stem cell markers. They also showed adipogenic and osteogenic differentiation potential. QPCR analysis revealed a significant upregulation in the expression of some pluripotency genes including OCT4, SOX2, NANOG, REX1 and ESG1 in the reprogrammed ADSCs compared to the control group.

Conclusion:

These findings showed that mouse ESC extract can be used to induce reprogramming of human ADSCs. In fact, this method is applicable for reprogramming of human adult stem cells to a more pluripotent sate and may have a potential in regenerative medicine.

Study of the chlorpyrifos neurotoxicity using neural differentiation of adipose tissue-derived stem cells

Chlorpyrifos (CPF) is the most commonly used organophosphorus insecticide which causes neurodevelopmental toxicity. So far, animals have been used as ideal models for neurotoxicity studies, but working with animals is very expensive, laborious, and ethically challenging. This has encouraged researchers to seek alternatives. During recent years, several studies have reported successful differentiation of embryonic and adult stem cells to neurons. This has provided an excellent model for neurotoxicologic studies. In this study, neural differentiation of mouse adipose tissue-derived stem cells (ADSCs) was used as an in vitro model for investigation of CPF neurotoxicity. For this purpose, mouse ADSCs were cultured in a medium containing knockout serum replacement and were treated with different concentrations of CPF at several stages of differentiation. Cytotoxic effect of CPF and the expression of neuron-specific genes and proteins were studied in the differentiating ADSCs. Furthermore, the activity of acetylcholinesterase was assessed by Ellman assay at different stages of differentiation. This study showed that up to 500 μM CPF did not alter viability of the undifferentiated ADSCs, whereas viability of the differentiating cells decreased with 500 μM CPF. CPF upregulated the expression of some neuron-specific genes and seemed to decrease the number of β-tubulin III and MAP2 proteins-expressing cells. There was no detectable acetylcholine esterase activity in differentiated ADSCs. In summary, it was shown that CPF treatment can decrease the viability of ADSC-derived neurons and dysregulate the expression of some neuronal markers through acetylcholinesterase-independent mechanisms. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1510-1519, 2016.

The expression of NPPA splice variants during mouse cardiac development

Natriuretic peptide precursor-A (NPPA) is an early and specific marker for functional myocardium of the embryonic heart. NPPA gene encodes for a precursor of atrial natriuretic peptide (ANP). So far, three alternatively spliced variants have been reported for NPPA in human. In mouse, no alternatively spliced transcript of NPPA has been reported. In the current study, we investigated the expression of NPPA gene during cardiac differentiation of mouse adipose-tissue-derived stem cells (ADSCs) and embryonic stem (ES) cells. As revealed by reverse-transcription polymerase chain reaction analysis, 2-week-differentiated cells expressed some cardiac-specific makers, including ANP. Three additional intron-retained splice variants of NPPA were also detected during cardiac differentiation of the ADSCs and ES cells. In addition, we detected three intron-retained splice variants of NPPA in 8.5-day mouse embryonic heart. In the mature cardiomyocytes of 1-week-old mice, only the correctly spliced isoform of NPPA gene was expressed. Freshly isolated stromal vascular fraction also expressed one intron-retained isoform of NPPA gene. In conclusion, our findings have provided evidence for the expression of intron-retained splices of NPPA mRNA during the early stages of mouse cardiogenesis as well as in the mouse adipose tissue.

Atrial and ventricular specification of ADSCs is stimulated by different doses of BMP4

To investigate the effect of BMP4 on cardiomyocyte differentiation of adipose tissue-derived stem cells (ADSCs), mouse ADSCs were treated with different concentrations of BMP4 in media containing fetal bovine serum (FBS) or Knockout™ Serum Replacement (KoSR). 3 weeks after cardiac induction, differentiated ADSCs expressed some cardiac-specific genes and proteins. BMP4 treatment upregulated the expression of cardiac transcription factors. In both FBS and KoSR-supplemented media, lower concentrations of BMP4 had a positive effect on the expression of MLC2A gene, while MLC2V was more expressed with higher concentrations of BMP4. BMP4 treatment in KoSR supplemented medium was more efficient for cardiac induction. Supplementation of culture media with insulin-transferrin-selenium improved the expression of MLC2A gene. The results of this study indicated that BMP4 is important for cardiac differentiation of the ADSCs. However, BMP4 was not enough for structural and functional maturation of the ADSC-derived cardiomyocytes.

Electron microscopic study of mouse embryonic stem cell-derived cardiomyocytes

Differentiation of embryonic stem cell (ESC)-derived embryoid bodies (EBs) is a heterogeneous process. ESCs can differentiate in vitro into different cell types including beating cardiomyocytes. The main aim of the present study was to develop an improved preparation method for scanning electron microscopic study of ESC-derived cardiac bundles and to investigate the fine structural characteristics of mouse ESCs-derived cardiomyocytes using electron microscopy. The mouse ESCs differentiation was induced by EBs' development through hanging drop, suspension and plating stages. Cardiomyocytes appeared in the EBs' outgrowth as beating clusters that grew in size and formed thick branching bundles gradually. Cardiac bundles showed cross striation even when they were observed under an inverted microscope. They showed a positive immunostaining for cardiac troponin I and α-actinin. Transmission and scanning electron microscopy (TEM & SEM) were used to study the structural characteristics of ESC-derived cardiomyocytes. Three weeks after plating, differentiated EBs showed a superficial layer of compact fibrous ECM that made detailed observation of cardiac bundles impossible. We tried several preparation methods to remove unwanted cells and fibers, and finally we revealed the branching bundles of cardiomyocytes. In TEM study, most cardiomyocytes showed parallel arrays of myofibrils with a mature sarcomeric organization marked by H-bands, M-lines and numerous T-tubules. Cardiomyocytes were connected to each other by intercalated discs composed of numerous gap junctions and fascia adherences.

Cell based-gene delivery approaches for the treatment of spinal cord injury and neurodegenerative disorders

Cell based-gene delivery has provided an important therapeutic strategy for different disorders in the recent years. This strategy is based on the transplantation of genetically modified cells to express specific genes and to target the delivery of therapeutic factors, especially for the treatment of cancers and neurological, immunological, cardiovascular and heamatopoietic disorders. Although, preliminary reports are encouraging, and experimental studies indicate functionally and structurally improvements in the animal models of different disorders, universal application of this strategy for human diseases requires more evidence. There are a number of parameters that need to be evaluated, including the optimal cell source, the most effective gene/genes to be delivered, the optimal vector and method of gene delivery into the cells and the most efficient route for the delivery of genetically modified cells into the patient. Also, some obstacles have to be overcome, including the safety and usefulness of the approaches and the stability of the improvements. Here, recent studies concerning with the cell-based gene delivery for spinal cord injury and some neurodegenerative disorders such as amyotrophic lateral sclerosis, Parkinson's disease and Alzheimer's disease are briefly reviewed, and their exciting consequences are discussed.

Effect of bone morphogenetic protein-4 on cardiac differentiation from mouse embryonic stem cells in serum-free and low-serum media

In spite of previous reports, the precise role of bone morphogenetic proteins (BMPs) on cardiomyocyte differentiation, especially in the absence or presence of minimum amount of serum in culture medium is still unclear. So, the aim of the present study was to investigate the effect of BMP-4 on mouse embryonic stem cells (ESCs)-derived cardiomyocyte differentiation in serum-free and low-serum media. The mouse ESCs differentiation to cardiomyocytes was induced by embryoid bodies' (EBs') development through hanging drop, suspension and plating stages. Different models of differentiation were designed according to addition of fetal bovine serum (FBS) or knockout serum replacement (KoSR) to the medium of three stages. 10 ng/ml BMP-4 was added throughout the suspension period. Up to 30 days after plating, contraction and beating frequency were monitored and evaluated daily. The growth characteristics of cardiomyocytes were assessed by cardioactive drugs, immunocytochemistry, transmission electron microscopy (TEM) and reverse transcription-polymerase chain reaction (RT-PCR). In the complete absence of serum, neither control nor BMP-4 treated groups resulted in cardiac differentiation. Addition of FBS to hanging drop stage resulted in the appearance of beating cardiac clusters in some BMP-4 treated EBs. In the best designed differentiation model in which only hanging drop and the first 24 h of plating stage was carried out at the presence of FBS, the BMP-4 treatment resulted in cardiac differentiation in EBs characterized by positive immunostaining for the applied antibodies, chronotropic response to the cardioactive drugs and cardiac-specific genes expression at different developmental stages. These cardiomyocytes showed immature myofibrils and numerous intercellular junctions. In conclusion, BMP-4 is unable to induce cardiomyocyte differentiation from mouse ESCs in serum-free models, and at least small amount of FBS in hanging drop stage is necessary. Furthermore, serum factors are not strictly necessary after the initial activation, but they do favor a better differentiation of cardiomyocytes.

Effect of bone morphogenetic protein-4 (BMP-4) on cardiomyocyte differentiation from mouse embryonic stem cell

The present study was designed to evaluate the effect of BMP-4 on mouse embryonic stem cells (ESCs)-derived cardiomyocyte. Cardiac differentiation of the mouse ESCs was initiated by embryoid bodies (EBs) formation in hanging drops, transfer of EBs to the suspension culture and then plating onto gelatin-coated tissue culture plates. BMP-4 was added to culture medium throughout the suspension period. Cultures were observed daily with an inverted microscope for the appearance of contracting clusters. At the early, intermediate and terminal stages of differentiation, the choronotropic responses of cardiomyocytes to cardioactive drugs were assessed, and the cardiomyocytes immunostained for cardiac troponin I, desmin, alpha-actinin and nebulin. The contracting clusters were isolated for ultrastructural evaluation, at day 14 after plating. Moreover, total RNA extracted from contracting EBs of early and terminal stages of differentiation were examined for oct-4, alpha- and beta-myosin heavy chain, myosin light chain-2V and atrial natriuretic factor expression. The BMP-4 treatment resulted in a decrease in the percent of beating EBs and the percent of developing cardiomyocytes per EBs. As a whole, the chronotropic responses of beating cardiac clusters to cardioactive drugs in control group were better than BMP-4 treated group. The cardiomyocytes of both groups were positive immunostained for applied antibodies except for nebulin. Moreover, in the BMP-4 treated group, the ultrastructural characteristics and cardiac-specific genes expression were all retarded in the terminal stage of cardiomyocytes development. In conclusion, BMP-4 had an inhibitory effect on cardiomyocyte differentiation from the mouse ESCs in terms of ultrastructural characteristics, genes expression and functional properties.

Effect of bone morphogenetic protein-4 (BMP-4) on adipocyte differentiation from mouse embryonic stem cells

Embryonic stem (ES) cells can differentiate spontaneously into various lineages in vitro. However, spontaneous commitment of ES cells to the adipocyte lineage is rare. In the present study, bone morphogenic protein-4 (BMP-4) is described as a factor inducing adipocyte differentiation from ES cells at a high rate. For this reason, ES-cell-derived embryoid bodies (EBs) in suspension cultures were exposed to different doses of BMP-4 for 5 days before they were plated onto gelatin-coated tissue culture plates. Moreover, the effect of serum-containing and serum-free media in three different combinations was assessed. Plated EBs, stained with Sudan Black and processed for transmission and scanning electron microscopy, were observed daily for adipocyte formation. Treatment with BMP-4 resulted in the appearance of adipocyte clusters in EBs' outgrowth, depending on the doses applied. Early in differentiation, many small fat droplets were observed in adipocytes, while later on they coalesced and formed a few large fat droplets. Adipocyte clusters had a fibrillar and vascular stroma, and each adipocyte was surrounded with a reticular external lamina. Furthermore, the appearance and development of adipocytes and their changes following 2-3 weeks of starvation mimicked live adipose tissue. In fact, understanding the biological activity of growth and differentiation factors is needed to regulate and direct stem cell differentiation to specific cell types in vitro.

Quantitative and qualitative changes of the seminiferous epithelium induced by Ga. Al. As. (830 nm) laser radiation

BACKGROUND AND OBJECTIVES

Low level laser radiation stimulates both nucleic acid synthesis and cellular proliferation in E. coli, Hela tumor cells, fibroblasts, lymphocytes, and thyroid cells. It has been introduced as a therapeutic modality; nevertheless few studies have been carried out to determine the effects of laser radiation on the testes or spermatogenesis. The aim of this study was to determine the quantitative and qualitative changes of the seminiferous epithelium after Ga. Al. As. (830 nm) laser radiation.

STUDY DESIGN/MATERIALS AND METHODS

The left testes of Sprague-Dawley rats were daily exposed to laser light for 15 days; so the cumulative doses used 28.05 and 46.80 J/cm(2) in two experimental groups. Sampling carried out 24 hours after the last treatment and samples were processed for LM and TEM study.

RESULTS

The number of germ cells specially the pachytene spermatocytes and elongated spermatids increased after 28.05 J/cm(2) laser radiation. Ultrastructural features of germ and Sertoli cells in this group were similar to that of control; while laser irradiation at 46.80 J/cm(2) had a destructive effect on the seminiferous epithelium such as dissociation of immature spermatids and evident ultrastructural changes in them.

CONCLUSIONS

The findings confirmed the existence of a biostimulatory threshold of applied laser energy and the importance of determining it for clinical applications. Moreover, it was revealed that low doses of laser light have a biostimulatory effect on the spermatogenesis and may provide benefits to the patients with oligospermia and azoospermia.