Human-induced pluripotent stem cells-derived retinal pigmented epithelium, a new horizon for cells-based therapies for age-related macular degeneration.

Retinal pigment epithelium (RPE) degeneration is the hallmark of age-related macular degeneration (AMD). AMD, as one of the most common causes of irreversible visual impairment worldwide, remains in need of an appropriate approach to restore retinal function. Wet AMD, which is characterized by neovascular formation, can be stabilized by currently available therapies, including laser photocoagulation, photodynamic therapy, and intraocular injections of anti-VEFG (anti-vascular endothelial growth factor) therapy or a combination of these modalities. Unlike wet AMD, there is no effective therapy for progressive dry (non-neovascular) AMD. However, stem cell-based therapies, a part of regenerative medicine, have shown promising results for retinal degenerative diseases such as AMD. The goal of RPE cell therapy is to return the normal structure and function of the retina by re-establishing its interaction with photoreceptors, which is essential to vision. Considering the limited source of naturally occurring RPE cells, recent progress in stem cell research has allowed the generation of RPE cells from human pluripotent cells, both embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSC). Since iPSCs face neither ethical arguments nor significant immunological considerations when compared to ESCs, they open a new horizon for cell therapy of AMD. The current study aims to discuss AMD, review the protocols for making human iPSCs-derived RPEs, and summarize recent developments in the field of iPSC-derived RPEs cell therapy.

Adoptive NK-cell transfer as a potential treatment paradigm for Wilms tumor: A preclinical study.

BACKGROUND: Natural killer (NK) cell therapy has been shown to be effective in the treatment of some cancers. However, the effects of this adoptive immunotherapy have not been investigated for Wilms tumor (WT). In this study, the effects of adoptive NK-cell transfer on a patient-derived xenograft (PDX) model of anaplastic WT were evaluated, and the impacts of cell source and ex vivo activation strategy on the therapeutic efficacy of NK-cell product were appraised. METHODS: NK cells were isolated from human peripheral blood mononuclear cells (NKPB ) and human cord blood (NKCB ), and were expanded and activated using a cytokine cocktail. Another group of NK cells (NKET ) was produced through activation with the exosomes extracted from previously challenged NKPB cells with WT. PDX-bearing mice were treated with clinically relevant doses of NKPB , NKCB , NKET , standard chemotherapy, and placebo (phosphate-buffered saline). RESULTS: PDX models treated with NKCB showed a better survival rate, though the difference among the study groups was not significant. Compared with the placebo control group, NKCB significantly improved the histopathologic response, NKPB significantly inhibited the proliferation of neoplastic cells, and NKET led to a significant decrease in the metastasis score (all p-values <.05). Standard chemotherapy provided the greatest tumor growth inhibition and the lowest mitotic count, though it did not show any significant advantage over NK-cell therapies in any of the outcome parameters in two-by-two comparisons. CONCLUSIONS: This study spotlights the efficacy of adoptive NK-cell transfer as a potential treatment candidate for high-risk WT.

An open-label phase 1 clinical trial of the allogeneic side population adipose-derived mesenchymal stem cells in SMA type 1 patients.

INTRODUCTION: Spinal muscular atrophy (SMA), an autosomal recessive neurodegenerative disorder of alpha motor neurons of spinal cord associated with progressive muscle weakness and hypotonia, is the most common genetic cause of infant mortality. Although there is few promising treatment for SMA, but the field of translational research is active in it, and stem cell-based therapy clinical trials or case studies are ongoing. Combination of different therapeutic approaches for noncurative treatments may increase their effectiveness and compliance of patients. We present a phase 1 clinical trial in patients with SMA1 who received side population adipose-derived mesenchymal stem cells (SPADMSCs). METHODS: The intervention group received three intrathecal administrations of escalating doses of SPADMSCs and followed until 24 months or the survival time. The safety analysis was assessed by controlling the side effects and efficacy evaluations performed by the Hammersmith Infant Neurological Examination (HINE), Ballard score, and electrodiagnostic (EDX) evaluation. These evaluations were performed before intervention and at the end of the follow-up. RESULTS: The treatment was safe and well tolerated, without any adverse event related to the stem cell administration. One of the patients in the intervention group was alive after 24 months of study follow-up. He is a non-sitter 62-month-old boy with appropriate weight gain and need for noninvasive ventilation (NIV) for about 8 h per day. Clinical scores, need for supportive ventilation, and number of hospitalizations were not meaningful parameters in the response of patients in the intervention and control groups. All five patients in the intervention group showed significant improvement in the motor amplitude response of the tibial nerve (0.56mV; p: 0.029). CONCLUSION: This study showed that SPADMSCs therapy is tolerable and safe with promising efficacy in SMA I. Probably same as other treatment strategies, early intervention will increase its efficacy and prepare time for more injections. We suggest EDX evaluation for the follow-up of treatment efficacy.

Will stem cells from fat and growth factors from blood bring new hope to female patients with reproductive disorders?

Female reproductive system disorders (FRSD) with or without infertility are prevalent women's health problems with a variety of treatment approaches including surgery and hormone therapy. It currently considering to sub-branch of regenerative medicine including stem cells or growth factors injection-based delivery treatment might be improved female reproductive health life. The most common products used for these patients treatment are autologous cell or platelet-based products from patients, including platelet-rich plasma, plasma rich in growth factor, platelet-rich fibrin, and stromal vascular fraction. In this review, we discuss each of the above products used in treatment of FRSD and critically evaluate the clinical outcome.

Overexpression of SMN2 Gene in Motoneuron-Like Cells Differentiated from Adipose-Derived Mesenchymal Stem Cells by Ponasterone A.

Cell therapy and stem cell transplantation strategies have provided potential therapeutic approaches for the treatment of neurological disorders. Adipose-derived mesenchymal stem cells (ADMSCs) are abundant adult stem cells with low immunogenicity, which can be used for allogeneic cell replacement therapies. Differentiation of ADMSCs into acetylcholine-secreting motoneurons (MNs) is a promising treatment for MN diseases, such as spinal muscular atrophy (SMA), which is associated with the level of SMN1 gene expression. The SMN2 gene plays an important role in MN disorders, as it can somewhat compensate for the lack of SMN1 expression in SMA patients. Although the differentiation potential of ADMSCs into MNs has been previously established, overexpression of SMN2 gene in a shorter period with a longer survival has yet to be elucidated. Ponasterone A (PNA), an ecdysteroid hormone activating the PI3K/Akt pathway, was studied as a new steroid to promote SMN2 overexpression in MNs differentiated from ADMSCs. After induction with retinoic acid, sonic hedgehog, forskolin, and PNA, MN phenotypes were differentiated from ADMSCs, and immunochemical staining, specific for ß-tubulin, neuron-specific enolase, and choline acetyltransferase, was performed. Also, the results of real-time PCR assay indicated nestin, Pax6, Nkx2.2, Hb9, Olig2, and SMN2 expression in the differentiated cells. After 2 weeks of treatment, cultures supplemented with PNA showed a longer survival and a 1.2-fold increase in the expression of SMN2 (an overall 5.6-fold increase; *P ≤ 0.05), as confirmed by the Western blot analysis. The PNA treatment increased the levels of ChAT, Isl1, Hb9, and Nkx2 expression in MN-like cells. Our findings highlight the role of PNA in the upregulation of SMN2 genes from MSC-derived MN-like cells, which may serve as a potential candidate in cellular therapy for SMA patients.

Natural Killer Cells from the Subcutaneous Adipose Tissue Underexpress the NKp30 and NKp44 in Obese Persons and Are Less Active against Major Histocompatibility Complex Class I Non-Expressing Neoplastic Cells.

There are many types of leukocytes reside in subcutaneous adipose tissue (SAT), and among them, natural killer cells (NKs) comprise a major part. We show that the NKs that reside in the SAT (adipose tissue-derived NK cells; ADNKs) of the abdominal region found with phenotypic differences from the NKs circulating in the peripheral blood derived NK cells (PBNKs). In this survey, flow cytometry phenotyping was used to study the differences between the natural cytotoxicity receptor expression on ADNKs and PBNKs of both obese and lean persons. Also, their cytotoxicity and cytokine production patterns were evaluated. The activation experiments on isolated and expanded NKs with IL-2, IL-15, and IL-21 cytokines revealed the main population of the CD56dim within the total ADNKs of obese persons has an under-expression of NKp30 and NKp44 despite the unchanged levels of NKG2D. The data suggest the suppressive condition of the adipose tissue niche on the NKs response against sensitive major histocompatibility complex class I non-expressing neoplastic cells. As the NKs are the first line of the body's defense vs tumor formation, this change may lead to the development of transformed cells into the tumors.

NK Cell-derived Exosomes From NK Cells Previously Exposed to Neuroblastoma Cells Augment the Antitumor Activity of Cytokine-activated NK Cells.

Immune cell-derived exosomes can increase immunity against tumors. In contrast, tumor-derived exosomes can reduce the immunity and can change the tumor microenvironment to further develop and provide metastasis. These effects take place by an alteration in the innate and adaptive immune cell functions. In this experiment, we studied the natural killer (NK) cells' effectiveness on tumor cells after expansion and thereafter incubated it with exosomes. The exosomes were derived from 2 populations of NK cells: (1) naive NK cells and, (2) NK cells previously exposed to neuroblastoma (NB) cells. Moreover, we have studied the NB-derived exosomes on NK cell function. The molecular load of the characterized exosomes (by means of nanoparticle-tracking analysis, flow cytometry, scanning electron microscopy, and western blot) from NK cells exposed to the NB cell revealed their expression of natural killer cell receptors in addition to CD56, NKG2D, and KIR2DL2 receptors. These exosomes were used to treat NK cells and thereafter administered to NB tumor cells both in vitro and in vivo. Our results showed some kind of NK cells' education by the exosomes. This education from NK cells previously exposed to NB cell-derived exosomes caused efficient and greater cytotoxicity against NB tumors, but NB-derived exosomes act as tumor promoters by providing a tumor supporting niche. Hence, this method of preparing the exosomes has a dramatic effect on activation of anti-NK cells against NB cells.

Differentiation of human endometrial stem cells into urothelial cells on a three-dimensional nanofibrous silk-collagen scaffold: an autologous cell resource for reconstruction of the urinary bladder wall.

Reconstruction of the bladder wall via in vitro differentiated stem cells on an appropriate scaffold could be used in such conditions as cancer and neurogenic urinary bladder. This study aimed to examine the potential of human endometrial stem cells (EnSCs) to form urinary bladder epithelial cells (urothelium) on nanofibrous silk-collagen scaffolds, for construction of the urinary bladder wall. After passage 4, EnSCs were induced by keratinocyte growth factor (KGF) and epidermal growth factor (EGF) and seeded on electrospun collagen-V, silk and silk-collagen nanofibres. Later we tested urothelium-specific genes and proteins (uroplakin-Ia, uroplakin-Ib, uroplakin-II, uroplakin-III and cytokeratin 20) by immunocytochemistry, RT-PCR and western blot analyses. Scanning electron microscopy (SEM) and histology were used to detect cell-matrix interactions. DMEM/F12 supplemented by KGF and EGF induced EnSCs to express urothelial cell-specific genes and proteins. Either collagen, silk or silk-collagen scaffolds promoted cell proliferation. The nanofibrous silk-collagen scaffolds provided a three-dimensional (3D) structure to maximize cell-matrix penetration and increase differentiation of the EnSCs. Human EnSCs seeded on 3D nanofibrous silk-collagen scaffolds and differentiated to urothelial cells provide a suitable source for potential use in bladder wall reconstruction in women.

Citalopram increases the differentiation efficacy of bone marrow mesenchymal stem cells into neuronal-like cells.

Several studies have demonstrated that selective serotonin reuptake inhibitor antidepressants can promote neuronal cell proliferation and enhance neuroplasticity both in vitro and in vivo. It is hypothesized that citalopram, a selective serotonin reuptake inhibitor, can promote the neuronal differentiation of adult bone marrow mesenchymal stem cells. Citalopram strongly enhanced neuronal characteristics of the cells derived from bone marrow mesenchymal stem cells. The rate of cell death was decreased in citalopram-treated bone marrow mesenchymal stem cells than in control cells in neurobasal medium. In addition, the cumulative population doubling level of the citalopram-treated cells was significantly increased compared to that of control cells. Also BrdU incorporation was elevated in citalopram-treated cells. These findings suggest that citalopram can improve the neuronal-like cell differentiation of bone marrow mesenchymal stem cells by increasing cell proliferation and survival while maintaining their neuronal characteristics.

Sertraline increases the survival of retinoic acid induced neuronal cells but not glial cells from human mesenchymal stem cells.

An increase in the number of viable in vitro differentiated neuronal cells is important for their use in clinics. A proportion of differentiated cells lose their viability before being used, and therefore we decided to use a pharmacological agent, sertraline, to increase neural cell differentiation and their survival. Purified endometrial stem cells (EnSCs) were examined for neuronal and glial cell specific markers after retinoic acid (RA) and sertraline treatment via RT-PCR, immunocytochemistry and Western blot analysis. The survival of differentiated cells was measured by MTT assay and the frequency of apoptosis, demonstrated by caspase-3-like activity. EnSCs were differentiated into neuronal cells after RA induction. Sertraline increased neuronal cell differentiation by 1.2-fold and their survival by 1.4-fold, and decreased from glial cell differentiation significantly. The findings indicate that sertraline could be used to improve the in vitro differentiation process of stem cells into neuronal cells, and may be involved in regenerative pharmacology in future.

λ Phage nanobioparticle expressing apoptin efficiently suppress human breast carcinoma tumor growth in vivo.

Using phages is a novel field of cancer therapy and phage nanobioparticles (NBPs) such as λ phage could be modified to deliver and express genetic cassettes into eukaryotic cells safely in contrast with animal viruses. Apoptin, a protein from chicken anemia virus (CAV) has the ability to specifically induce apoptosis only in carcinoma cells. We presented a safe method of breast tumor therapy via the apoptin expressing λ NBPs. Here, we constructed a λ ZAP-CMV-apoptin recombinant NBP and investigated the effectiveness of its apoptotic activity on BT-474, MDA-MB-361, SKBR-3, UACC-812 and ZR-75 cell lines that over-expressing her-2 marker. Apoptosis was evaluated via annexin-V fluorescent iso-thiocyanate/propidium iodide staining, flow-cytometric method and TUNEL assay. Transfection with NBPs carrying λ ZAP-CMV-apoptin significantly inhibited growth of all the breast carcinoma cell lines in vitro. Also nude mice model implanted BT-474 human breast tumor was successfully responded to the systemic and local injection of untargeted recombinant λ NBPs. The results presented here reveal important features of recombinant λ nanobioparticles to serve as safe delivery and expression platform for human cancer therapy.

Neurogenesis and increase in differentiated neural cell survival via phosphorylation of Akt1 after fluoxetine treatment of stem cells.

Fluoxetine (FLX) is a selective serotonin reuptake inhibitor (SSRI). Its action is possibly through an increase in neural cell survival. The mechanism of improved survival rate of neurons by FLX may relate to the overexpression of some kinases such as Akt protein. Akt1 (a serine/threonine kinase) plays a key role in the modulation of cell proliferation and survival. Our study evaluated the effects of FLX on mesenchymal stem cell (MSC) fate and Akt1 phosphorylation levels in MSCs. Evaluation tests included reverse transcriptase polymerase chain reaction, western blot, and immunocytochemistry assays. Nestin, MAP-2, and ß-tubulin were detected after neurogenesis as neural markers. Ten µ M of FLX upregulated phosphorylation of Akt1 protein in induced hEnSC significantly. Also FLX did increase viability of these MSCs. Continuous FLX treatment after neurogenesis elevated the survival rate of differentiated neural cells probably by enhanced induction of Akt1 phosphorylation. This study addresses a novel role of FLX in neurogenesis and differentiated neural cell survival that may contribute to explaining the therapeutic action of fluoxetine in regenerative pharmacology.

Endometrial stem cell differentiation into smooth muscle cell: a novel approach for bladder tissue engineering in women.

OBJECTIVE: To investigate manufacturing smooth muscle cells (SMCs) for regenerative bladder reconstruction from differentiation of endometrial stem cells (EnSCs), as the recent discovery of EnSCs from the lining of women's uteri, opens up the possibility of using these cells for tissue engineering applications, such as building up natural tissue to repair prolapsed pelvic floors as well as building urinary bladder wall. MATERIALS AND METHODS: Human EnSCs that were positive for cluster of differentiation 146 (CD146), CD105 and CD90 were isolated and cultured in Dulbecco's modified Eagle/F12 medium supplemented with myogenic growth factors. The myogenic factors included: transforming growth factor ß, platelet-derived growth factor, hepatocyte growth factor and vascular endothelial growth factor. Differentiated SMCs on bioabsorbable polyethylene-glycol and collagen hydrogels were checked for SMC markers by real-time reverse-transcriptase polymerase chain reaction (RT-PCR), western blot (WB) and immunocytochemistry (ICC) analyses. RESULTS: Histology confirmed the growth of SMCs in the hydrogel matrices. The myogenic growth factors decreased the proliferation rate of EnSCs, but they differentiated the human EnSCs into SMCs more efficiently on hydrogel matrices and expressed specific SMC markers including α-smooth muscle actin, desmin, vinculin and calponin in RT-PCR, WB and ICC experiments. The survival rate of cultures on the hydrogel-coated matrices was significantly higher than uncoated cultures. CONCLUSIONS: Human EnSCs were successfully differentiated into SMCs, using hydrogels as scaffold. EnSCs may be used for autologous bladder wall regeneration without any immunological complications in women. Currently work is in progress using bioabsorbable nanocomposite materials as EnSC scaffolds for developing urinary bladder wall tissue.

Recombinant λ bacteriophage displaying nanobody towards third domain of HER-2 epitope inhibits proliferation of breast carcinoma SKBR-3 cell line.

Phage display of many nanobodies via filamentous phage in combination with helper phage has been reported by many scientists. The aim of this study was to produce lambda (λ) bacteriophage displaying high-affinity nanobody against HER-2 expressing breast carcinoma cells. Bacteriophage λ is a temperate phage with inherent biological safety in mammalian cells. Here we report the construction of a recombinant λ phage that efficiently expresses specific nanobody towards third domain of HER-2 target on SKBR-3 and MCF-7 cell lines in vitro. We constructed recombinant λ phage particles containing a mammalian expression cassette, C-Myc tagged, encoding VHH gene of camelid anti HER-2 third domain epitope using λ ZAP-cytomegalic virus (CMV) vector. The SKBR-3, MCF-7 and human endometrial stem cells were treated by the nanobody displayed recombinant λ phage. The cell growth inhibition assay was performed by MTT Cell Viability Assay Kit. After the fourth round of biopanning there was a significant enrichment in the phage specifically binding to the antigen. The ratio of targeted phage increased approximately 1,000-fold in the fifth round. The nanobody expressed by λ ZAP-CMV-VHH phagemid cloned in λ bioparticles significantly inhibited the proliferation of HER-2 positive SKBR-3 and MCF-7 cells. Recombinant bacteriophage λ ZAP-CMV-VHH-cDNA could be used efficiently for construction of nanobodies to mortify HER-2 positive breast carcinoma cells as a nanomedical therapeutic.

Hydroxy decenoic acid down regulates gtfB and gtfC expression and prevents Streptococcus mutans adherence to the cell surfaces.

BACKGROUND: 10-Hydroxy-2-decenoic acid, an unsaturated fatty acid is the most active and unique component to the royal jelly that has antimicrobial properties. Streptococcus mutans is associated with pathogenesis of oral cavity, gingivoperiodontal diseases and bacteremia following dental manipulations. In the oral cavity, S. mutans colonize the soft tissues including tongue, palate, and buccal mucosa. When considering the role of supragingival dental plaque in caries, the proportion of acid producing bacteria (particularly S. mutans), has direct relevance to the pathogenicity of the plaque. The genes that encode glucosyltransferases (gtfs) especially gtfB and gtfC are important in S. mutans colonization and pathogenesis. This study investigated the hydroxy-decenoic acid (HDA) effects on gtfB and gtfC expression and S. mutans adherence to cells surfaces. METHODS: Streptococcus mutans was treated by different concentrations of HPLC purified HDA supplied by Iran Beekeeping and Veterinary Association. Real time RT-PCR and western blot assays were conducted to evaluate gtfB and gtfC genes transcription and translation before and after HDA treatment. The bacterial attachment to the cell surfaces was evaluated microscopically. RESULTS: 500 µg ml-1 of HDA inhibited gtfB and gtfC mRNA transcription and its expression. The same concentration of HDA decreased 60% the adherence of S. mutans to the surface of P19 cells. CONCLUSION: Hydroxy-decenoic acid prevents gtfB and gtfC expression efficiently in the bactericide sub-concentrations and it could effectively reduce S. mutans adherence to the cell surfaces. In the future, therapeutic approaches to affecting S. mutans could be selective and it's not necessary to put down the oral flora completely.

Human endometrial stem cell neurogenesis in response to NGF and bFGF.

The potential of cell therapy is promising in nerve regeneration, but is limited by ethical considerations about the proper and technically safe source of stem cells. We report the successful differentiation of human EnSCs (endometrial stem cells) as a rich source of renewable and safe progenitors into high-efficiency cholinergic neurons. The extracellular signals of NGF (nerve growth factor) and bFGF (basic fibroblast growth factor) could induce cholinergic neuron differentiation. ChAT (choline acetyltransferase), MAP2 (microtubule associated protein 2) and NF-l (neurofilament L) increased after administration of bFGF and NGF to the EnSC cultures. trkC and FGFR2 (fibroblast growth factor receptor 2), which belong to the NGF and bFGF receptors respectively, were determined in populations of EnSCs. NGF, bFGF and their combination differentially influenced human EnSCs high efficiency differentiation. By inducing cholinergic neurons from EnSCs in a chemically defined medium, we could produce human neural cells without resorting to primary culture of neurons. This in vitro method provides an unlimited source of human neural cells and facilitates clinical applications of EnSCs for neurological diseases.

DHEA provides a microenvironment for endometrial stem cells neurogenesis.

Recently, transplantation of adult stem cells over embryonic stem cells increased in regenerative medicine. Among the adult stem cells, human endometrium stromal (hEnS) cells are under the strict control of the steroid hormones and have the potential to differentiate into other cell lineages including neural cells. Unfortunately these cells may lose their neurogenic differentiation ability upon extended expansion in cultures. To avoid the back-differentiation, it is important to establish growth conditions that support the rapid proliferation and stable differentiation of hEnS cells over extended periods of time without compromising their neuronal phenotype. Differentiation of transplanted cells is strongly influenced by environmental signals. The steroidal microenvironment of the stem cells plays a major role in controlling neurogenesis in the cultures. Dehydroepiandrosterone (DHEA) administration to the cultures could support this propose. DHEA enhance survival rates of dissociated neurons in cultures. It can activate AKT protein kinase pathway as well as nerve growth factor (NGF) that enhances neurogenesis efficiently. On the other hand it seems that DHEA increase survival rate of neural cells via production of brain derived neurotrophic factor (BDNF), indirectly. BDNF is a mediator product of the DHEA that promotes the differentiation and survival of neurons. Here, we offer that DHEA is a suitable candidate that could provide a microenvironment to stimulate neurogenesis and enhanced survival of newly formed neurons derived from hEnS cells. From the point that DHEA is the most abundant steroid in the body, marketed as a supplement and is increasingly self-prescription we hypothesized that it could be the safe and high available choice. This provides a better insight into the maintenance of neural cells for treatment of a wide variety of neurological diseases such as Alzheimer's and Parkinson's by non-invasively autologous cell therapy by hEnS cells especially in women.

The neurosteroid dehydroepiandrosterone could improve somatic cell reprogramming.

Expression of four major reprogramming transgenes, including Oct4, Sox2, Klf4 and c-myc, in somatic cells enables them to have pluripotency. These cells are iPSC (induced pluripotent stem cell) that currently show the greatest potential for differentiation into cells of the three germ lineages. One of the issues facing the successful reprogramming and clinical translation of iPSC technology is the high rate of apoptosis after the reprogramming process. Reprogramming is a stressful process, and the p53 apoptotic pathway plays a negative role in cell growth and self-renewal. Apoptosis via the p53 pathway serves as a major barrier in nuclear somatic cell reprogramming during iPSC generation. DHEA (dehydroepiandrosterone) is an abundant steroid that is produced at high levels in the adrenal cells, and withdrawal of DHEA increases the levels of p53 in the epithelial and stromal cells, resulting in increased levels of apoptotic cells; meanwhile, DHEA decreases cellular apoptosis. DHEA could improve the efficacy of reprogramming yield due to a decrease in apoptosis via the p53 pathway and an increase in cell viability.

A 5α-reductase inhibitor, finasteride, increases differentiation and proliferation of embryonal carcinoma cell-derived-neural cells.

Recent advances in stem cell biology have resulted in identifying new agents to differentiate stem cell-derived-neural cells. Different stem cell types have been shown to differentiate into neural cells. It has been shown that P19 line of embryonal carcinoma cells develops into neurons and astroglia after exposure to some hormones such as dehydroepiandrosterone (DHEA). Steroid 5α-reductase is a key enzyme in the conversion of several Δ4-3 keto steroids, such as testosterone into their respective 5α-reductase derivatives. Finasteride is a 5α-reductase inhibitor that inhibits conversion of testosterone to the more potent androgen dihydrotestosterone (DHT). Reduction in DHT and sustaining testosterone levels has an important impact on differentiation and proliferation of embryonal carcinoma cells to neural cells. We hypothesize that finasteride, a 5α-reductase inhibitor, will be differentiate embryonal carcinoma cell to the neural cell and increase their proliferation due to the elevation levels of testosterone, a neuroprotective neurosteroid.

Could the endogenous opioid, morphine, prevent neural stem cell proliferation?

In spite of widespread use of morphine to treat pain in patients, little is known about the effects of this opioid on many cells including stem cells. Moreover the studies have been shown controversial results about morphine effects on several kinds of cells. It is well-known that morphine exposure could decrease testosterone levels in brain and spinal cord. Morphine could increase the activity of 5α-redutase, the enzyme that converts testosterone into its respective 5α-redutase derivative dihydrotestosterone (DHT). Also it could increase aromatase activity that converts testosterone to estradiol. Proliferation of neural stem cells was observed in human stem cells after exposure to certain combinations of steroids especially testosterone. On the other hand DHT has negative effect in neural stem cell reproduction. Morphine induces over-expression of p53 gene that could mediate stem cell apoptosis. Therefore we hypothesized that due to reduction in the testosterone levels, elevation in the DHT levels, and over-expression of p53 gene, morphine could prevent neural stem cell proliferation.