Suppression of transforming growth factor-beta signaling enhances spermatogonial proliferation and spermatogenesis recovery following chemotherapy.

STUDY QUESTION: Could small molecules (SM) which target (or modify) signaling pathways lead to increased proliferation of undifferentiated spermatogonia following chemotherapy? SUMMARY ANSWER: Inhibition of transforming growth factor-beta (TGFb) signaling by SM can enhance the proliferation of undifferentiated spermatogonia and spermatogenesis recovery following chemotherapy. WHAT IS KNOWN ALREADY: Spermatogonial stem cells (SSCs) hold great promise for fertility preservation in prepubertal boys diagnosed with cancer. However, the low number of SSCs limits their clinical applications. SM are chemically synthesized molecules that diffuse across the cell membrane to specifically target proteins involved in signaling pathways, and studies have reported their ability to increase the proliferation or differentiation of germ cells. STUDY DESIGN, SIZE, DURATION: In our experimental study, spermatogonia were collected from four brain-dead individuals and used for SM screening in vitro. For in vivo assessments, busulfan-treated mice were treated with the selected SM (or vehicle, the control) and assayed after 2 (three mice per group) and 5 weeks (two mice per group). PARTICIPANTS/MATERIALS, SETTING, METHODS: We investigated the effect of six SM on the proliferation of human undifferentiated spermatogonia in vitro using a top-bottom approach for screening. We used histological, hormonal and gene-expression analyses to assess the effect of selected SM on mouse spermatogenesis. All experiments were performed at least in triplicate and were statistically evaluated by Student's t-test and/or one-way ANOVA followed by Scheffe's or Tukey's post-hoc. MAIN RESULTS AND THE ROLE OF CHANCE: We found that administration of SB431542, as a specific inhibitor of the TGFb1 receptor (TGFbR1), leads to a two-fold increase in mouse and human undifferentiated spermatogonia proliferation. Furthermore, injection of SB to busulfan-treated mice accelerated spermatogenesis recovery as revealed by increased testicular size, weight and serum level of inhibin B. Moreover, SB administration accelerated both the onset and completion of spermatogenesis. We demonstrated that SB promotes proliferation in testicular tissue by regulating the cyclin-dependent kinase (CDK) inhibitors 4Ebp1 and P57 (proliferation inhibitor genes) and up-regulating Cdc25a and Cdk4 (cell cycle promoting genes). LIMITATIONS, REASONS FOR CAUTION: The availability of human testis was the main limitation in this study. WIDER IMPLICATIONS OF THE FINDINGS: This is the first study to report acceleration of spermatogenesis recovery following chemotherapy by administration of a single SM. Our findings suggest that SB is a promising SM and should be assessed in future clinical trials for preservation of fertility in men diagnosed with cancer or in certain infertility cases (e.g. oligospermia). STUDY FUNDING/COMPETING INTEREST(S): This study was supported by Royan Institute and National Institute for Medical Research Development (NIMAD, grant no 963337) granted to H.B. The authors have no conflict of interest to report.

Rare case of an oligospermic male with 46,XX/46,XY tetragametic chimerism.

Chimerism, a rare human disorder, is assumed to be the result of an amalgamation of two separate zygotes in a single embryo. Studies have shown that the phenotypic spectrum of chimerism is variable and there is no definite genotype-phenotype correlation in patients with chimerism, therefore a majority of cases might remain undiagnosed. This study aims to investigate the possible mechanism of the chimerism in a 46,XX/46,XY infertile and phenotypically normal male, with 46,XX blood karyotype and normal spermatogenesis. We have used Interphase-FISH analysis to study the CEPX and CEPY regions on buccal and urine samples as well as molecular analysis of polymorphic short tandem repeats (STR) markers from 34 loci in order to discover the origin of 46,XX/46,XY. Analysis of X-linked and autosomal STR markers on blood, buccal tissue, urine, fibroblast and testis biopsy samples of the proband along with the blood sample of the patient's parents and siblings, showed divergent karyotypes in different tissues and tetragametic chimerism was diagnosed.

Cord Blood Karyotyping: A Safe and Non-Invasive Method for Postnatal Testing of Assisted Reproductive Technology Children.

BACKGROUND: To verify the hypothesis that the incidence of chromosomal abnormalities increases in babies conceived by different assisted reproduction procedures. The availability of the umbilical cord blood encouraged us to study this hypothesis via this method. MATERIALS AND METHODS: This is a descriptive study, umbilical cord blood samples of assisted reproductive technology (ART) children were analyzed with standard cytogenetic techniques (G banding). Karyotyping was possible in 109 cases. RESULTS: The number of abnormal cases was four (3.7%), among which, three cases (2.8%) were inherited and only 1 case (0.9%) was a de novo translocation. In total, the incidence of de novo chromosomal abnormalities was in the range observed in all live births in the general population (0.7-1%). CONCLUSION: No significant difference in the incidence of chromosomal abnormality was found between ART and naturally conceived babies. To date, several studies have examined the medical and developmental outcome of ART children and still have not reached a definite conclusion. Genetic counseling is recommended as an integral part of planning of treatment strategies for couples wishing to undergo ART.

Generation of Rat Embryonic Germ Cells via Inhibition of TGFß and MEK Pathways.

OBJECTIVE: Embryonic germ (EG) cells are the results of reprogramming primordial germ cells (PGC) in vitro. Studying these cells can be of benefit in determining the mechanism by which specialized cells acquire pluripotency. Therefore in the current study we have tried to derive rat EG cells with inhibition of transforming growth factor-ß (TGFß) and mitogen-activated protein kinase kinase (MEK) signaling pathways. MATERIALS AND METHODS: In this experimental study, rat PGCs were cultured under feeder free condition with two small molecules that inhibited the above mentioned pathways. Under this condition only two-day presence of stem cell factor (SCF) as a survival factor was applied for PGC reprogramming. Pluripotency of the resultant EG cells were further confirmed by immunofluorescent staining, directed differentiation ability to neural and cardiac cells, and their contribution to teratoma formation as well. Moreover, chromosomal stability of two different EG cells were assessed through G-banding technique. RESULTS: Formerly, derivation of rat EG cells were observed solely in the presence of glycogen synthase kinase-3 (GSK3ß) and MEK pathway inhibitors. Due to some drawbacks of inhibiting GSK3ß molecules such as increases in chromosomal aberrations, in the present study we have attempted to assess a feeder-free protocol that derives EG cells by the simultaneous suppression of TGFß signaling and the MEK pathway. We have shown that rat EG cells could be generated in the presence of two inhibitors that suppressed the above mentioned pathways. Of note, inhibition of TGFß instead of GSK3ß significantly maintained chromosomal integrity. The resultant EG cells demonstrated the hallmarks of pluripotency in protein expression level and also showed in vivo and in vitro differentiation capacities. CONCLUSION: Rat EG cells with higher karyotype stability establish from PGCs by inhibiting TGFß and MEK signaling pathways.

Inhibition of TGFß signaling promotes ground state pluripotency.

Embryonic stem (ES) cells are considered to exist in a ground state if shielded from differentiation triggers. Here we show that FGF4 and TGFß signaling pathway inhibitors, designated R2i, not only provide the ground state pluripotency in production and maintenance of naïve ES cells from blastocysts of different mouse strains, but also maintain ES cells with higher genomic integrity following long-term cultivation compared with the chemical inhibition of the FGF4 and GSK3 pathways, known as 2i. Global transcriptome analysis of the ES cells highlights augmented BMP4 signaling pathway. The crucial role of the BMP4 pathway in maintaining the R2i ground state pluripotency is demonstrated by BMP4 receptor suppression, resulting in differentiation and cell death. In conclusion, by inhibiting TGFß and FGF signaling pathways, we introduce a novel defined approach to efficiently establish the ground state pluripotency.

Enhanced generation of human embryonic stem cells from single blastomeres of fair and poor-quality cleavage embryos via inhibition of glycogen synthase kinase ß and Rho-associated kinase signaling.

STUDY QUESTION: Could selected pluripotency-enhancing small molecules (SMs) lead to efficient derivation of human embryonic stem cells (hESCs) from cleavage embryos-derived single blastomeres (SBs)? SUMMARY ANSWER: Inhibition of glycogen synthase kinase ß (GSK3ß) and Rho-associated kinase (ROCK) signaling can enhance the derivation of hESCs from cleavage embryo-derived SBs. WHAT IS KNOWN ALREADY: Parameters involved in sustaining the pluripotency of biopsied blastomeres for generating hESCs without causing injury to a viable embryo have remained obscure. This research seeks to improve the culture conditions for increasing the efficiency of deriving hESCs from SBs from cleavage-stage embryos by using SMs. STUDY DESIGN, SIZE, DURATION: In order to identify SMs which may enhance hESC generation from SBs, 11 pluripotency-enhancing SMs were screened and CHIR99021 (CH), a GSK3ß inhibitor, was selected. To optimize culture condition in hESC generation from SMs, we used ROCK inhibitor Y27632 (Y) and basic fibroblast growth factor in combination with CH or its alternative, Kenpaullone, in different time courses over 12 days. We also assessed a critical time point for CH + Y treatment of cleavage embryos from 4- to 8-cell embryo. In total, 224 embryos and 1607 SBs were used in the study. PARTICIPANTS/MATERIALS, SETTING, METHODS: Blastomeres of fair and poor-quality from 6- to 8-cell stage human embryos were mechanically dispersed and individually seeded into a 96-well plate that was precoated with mitotically inactivated feeder cells. Derivation of hESC line from each SB was carried out in hESC defined medium supplemented with SMs. Randomly selected hESC lines were evaluated by immunostaining for pluripotency markers, karyotype analysis and differentiation potential into the three embryonic germ layer derivatives. MAIN RESULTS AND THE ROLE OF CHANCE: We found that 3 µM CH was the only SM that was capable of directing SBs from fair and poor-quality 6-8-cell embryos into hESC lines. The application of hESC-conditioned medium had no additive effect on hESC establishment from SBs. Also, we indicated that CH combined with Y improved hESC generation efficiency by up to 31%. By using of Kenpaullone as an alternative to CH, we confirmed the involvement of GSK3 inhibition in hESC derivation from SBs. Interestingly, by treatment of 4-cell embryos, these SMs could enhance the derivation efficiency of SB-derived hESC lines up to 73% and the maximum number of hESC lines from SBs of one embryo was achieved in this state. LIMITATIONS, REASONS FOR CAUTION: The low quality of the embryos used in this study most likely had an effect on hESC generation. Furthermore, although we attempted to minimize any differences in inter-embryo quality, we cannot exclude the possibility that small differences in starting quality between embryos may have contributed to the differences observed, other than the addition of SMs. WIDER IMPLICATIONS OF THE FINDINGS: This approach would allow the establishment of autogeneic or allogeneic matched cells from embryos fertilized in vitro without destroying them. STUDY FUNDING/COMPETING INTEREST(S): This study was financially supported by the National Elite Foundation and the Royan Institute for Stem Cell Biology and Technology. The authors have no conflict of interest to declare.

Production of transgenic goats expressing human coagulation factor IX in the mammary glands after nuclear transfer using transfected fetal fibroblast cells.

There are growing numbers of recombinant proteins that have been expressed in milk. Thus one can consider the placement of any gene of interest under the control of the regulatory elements of a milk protein gene in a dairy farm animal. Among the transgene introducing techniques, only nuclear transfer (NT) allows 100 % efficiency and bypasses the mosaicism associated with counterpart techniques. In this study, in an attempt to produce a transgenic goat carrying the human coagulation factor IX (hFIX) transgene, goat fetal fibroblasts were electroporated with a linearized marker-free construct in which the transgene was juxtaposed to ß-casein promoter designed to secret the recombinant protein in goat milk. Two different lines of transfected cells were used as donors for NT to enucleated oocytes. Two transgenic goats were liveborn. DNA sequencing of the corresponding transgene locus confirmed authenticity of the cloning procedure and the complementary experiments on the whey demonstrated expression of human factor IX in the milk of transgenic goats. In conclusion, our study has provided the groundwork for a prosperous and promising approach for large-scale production and therapeutic application of hFIX expressed in transgenic goats.

A new efficient protocol for directed differentiation of retinal pigmented epithelial cells from normal and retinal disease induced pluripotent stem cells.

We describe a new, efficient protocol that involves the serial addition of noggin, basic fibroblast growth factor (bFGF), retinoic acid, and sonic hedgehog (Shh) for the differentiation of human induced pluripotent stem cells (hiPSC) to retinal pigmented epithelium (RPE) in a serum- and feeder-free adherent condition. hiPSC-RPE cells exhibited RPE morphology and specific molecular markers. Additionally, several hiPSC lines were generated from retinal-specific patients with Leber's congenital amaurosis, Usher syndrome, two patients with retinitis pigmentosa, and a patient with Leber's hereditary optic neuropathy. The RPE cells generated from these disease-specific hiPSCs expressed specific markers by the same RPE lineage-directed differentiation protocol. These findings indicate a new short-term, simple, and efficient protocol for differentiation of hiPSCs to RPE cells. Such specific retinal disease-specific hiPSCs offer an unprecedented opportunity to recapitulate normal and pathologic formation of human retinal cells in vitro, thereby enabling pharmaceutical screening, and potentially autologous cell replacement therapies for retinal diseases.

Long-term self-renewable feeder-free human induced pluripotent stem cell-derived neural progenitors.

Human induced pluripotent stem cells (hiPSCs) have led to an important revolution in stem cell research and regenerative medicine. To create patient-specific neural progenitors (NPs), we have established a homogenous, expandable, and self-renewable population of multipotent NPs from hiPSCs, using an adherent system and defined medium supplemented with a combination of factors. The established hiPSC-NPs highly expressed Nestin and Sox1. These NPs were continuously propagated for ~1 year without losing their potential to generate astrocytes, oligodendrocytes, and functional neurons and maintained a stable chromosome number. Voltage clamp analysis revealed outward potassium currents in hiPSC-NPs. The self-renewal characteristic of the NPs was demonstrated by a symmetrical mode of Nestin-positive cell division. Additionally, these hiPSC-NPs can be easily frozen and thawed in the presence of Rho-associated kinase (ROCK) inhibitor without losing their proliferation, karyotype stability, and developmental potential. The characteristics of our generated hiPSC-NPs provide the opportunity to use patient-specific or ready-to-use hiPSC-NPs in future biomedical applications.

A simple and efficient cryopreservation method for feeder-free dissociated human induced pluripotent stem cells and human embryonic stem cells.

BACKGROUND: An essential prerequisite for the future widespread application of human induced pluripotent (hiPSCs) and embryonic stem cells (hESCs) is the development of efficient cryopreservation methods to facilitate their storage and transportation. METHODS: We developed a simple and effective freezing/thawing method of single dissociated hESCs and hiPSCs in a feeder-free culture in the presence of Rho-associated kinase (ROCK) inhibitor Y-27632. RESULTS: Exposure to ROCK inhibitor Y-27632 in freezing solution alone does not significantly enhance the post-thaw survival rate of single dissociated hESCs and hiPSCs. However, when ROCK inhibitor was added to both pre- and post-thaw culture media, there was an enhancement in the survival rate, which further increased when ROCK inhibitor was added to Matrigel as well. Under these treatments, hESCs and hiPSCs retained typical morphology, stable karyotype, expression of pluripotency markers and the potential to differentiate into derivatives of all three germ layers after long-term culture. CONCLUSIONS: This method is an effective cryopreservation procedure for single dissociated hESCs in feeder-free culture, which is also applicable for single dissociated hiPSCs using a ROCK inhibitor. The cloning efficiency of hiPSCs and hESCs improves when ROCK inhibitor is added both in Matrigel and in medium in comparison with conventional addition to medium. Therefore, we believe this method would be useful for current and future applications of the pluripotent stem cells.