Recombinant Human Activin Research Articles

Identification of ActivinβA and Gonadotropin Regulation of the Activin System in the Ovary of Chinese Sturgeon Acipenser sinensis.

Activin is a dimeric growth factor with diverse biological activities in vertebrates. This study aimed to investigate the regulatory role of the activin signaling pathway in the ovary of the endangered, cultured sturgeon species Acipenser sinensis. One activinβA subunit was identified, with a full-length complementary DNA (cDNA) sequence of 1572 base pairs. Multiple sequence alignment suggested that ActivinβA shared high sequence identities with its counterparts in four other sturgeon species. Phylogenetic analysis indicated the conserved evolution of ActivinβA among vertebrates from mammals to fish species. Transcripts of activinβA were distributed ubiquitously in the liver, kidney, intestine, ovary, midbrain, hypothalamus, and pituitary, with the highest transcription found in the pituitary. In Chinese sturgeon ovarian cells, in vitro human recombinant Activin A incubation stimulated the activin system-related gene transcriptions of activinβA, follistatin, its receptors -activinRIIA and activinRIIB, and drosophila mothers against decapentaplegic proteins (smads) smad2, smad3, and smad4. Ovary development-related mRNA levels of cyp19a1a and aromatase receptors of erα and erβ were enhanced by Activin A or human chorionic gonadotropin (hCG) incubation. Furthermore, 15 IU/mL hCG treatment increased the transcription levels of activinβA, follistatin, activinRIIA, and smad2. This suggested that the activin system was functional for the regulation of ovary development in Chinese sturgeon, possibly under the regulation of gonadotropin, by recruiting activinβA, follistatin, activinRIIA, and smad2. These results were helpful for the molecular exploration of activin signaling in fish species, as well as the ovarian maturation regulation of A. sinensis.

Activin E upregulates uncoupling protein 1 and fibroblast growth factor 21 in brown adipocytes

Activin E activates brown and beige adipocytes and has been controversially implicated as a factor that induces obesity and fatty liver. Here, we sought to address this controversial issue by producing recombinant human activin E to evaluate its effects on HB2 brown adipocytes in vitro. Activin E increased uncoupling protein 1 (Ucp1) and fibroblast growth factor 21 (Fgf21) mRNA expression in the adipocytes. This upregulation was suppressed by SB431542, an inhibitor of activin receptor-like kinase (Alk) TGF-β type I receptors. SB431542 also inhibited the activin E-induced phosphorylation of Smad2/3. A promoter assay using a CAGA-Luc reporter and Alk expression vectors revealed that activin E activated the TGF-β/activin pathway via Alk7. The upregulation of Ucp1 and Fgf21 mRNA might be mediated through Alk7 and Smad2/3 phosphorylation. Activin E is a potential stimulator of energy expenditure by activating brown adipocytes and highlights its potential as a therapeutic target for treating obesity.

Production of Mature Recombinant Human Activin A in Transgenic Rice Cell Suspension Culture.

Activin A belongs to the transforming growth factor (TGF) family member, which exhibits a wide range of biological activities, including the regulation of cellular proliferation and differentiation and the promotion of neuronal survival. The isolation of AA from natural sources can only produce limited quantities of this bioactive protein. In this study, the whole gene of the precursor form of recombinant human activin A (rhAA) contains a signal peptide, and a pro-region and a mature region were cloned into an expression vector under the control of the rice α-amylase 3D (RAmy3D) promoter. To obtain the mature (active) form of rhAA, an enterokinase cleavage site was inserted between the pro-region and mature region of rhAA. The rice seed (Oryza sativa L. cv. Dongjin) was transformed with recombinant vectors by the Agrobacterium-mediated method, and the integration of the target gene into the plant genome was confirmed by genomic PCR. The transcript expression of rhAA in transgenic rice calli was confirmed by a Northern blot analysis of mRNA. The production of rhAA was verified by Western blot analysis and ELISA. The accumulation of secreted rhAA in the culture medium was purified by Ni2+-NTA. The mature form of AA was released from the precursor form of rhAA after proteolytically processing with enterokinase. Western blot shows that the mature AA was split into monomer and homodimer with molecular weights of 14 kDa and 28 kDa under reducing and non-reducing conditions, respectively. These results suggest that the mature form of rhAA could be produced and purified using transgenic rice cell suspension culture.

High-level production and purification of bioactive recombinant human activin A in Chinese hamster ovary cells

Activin A, a member of the TGF-β superfamily, is a homodimer of the inhibin βΑ subunit that plays a diversity of roles in biological processes. Because of its multiple functions, significant efforts have been made to produce activin A, however, unsatisfactory results were obtained due to its low level of expression. In this study, a stable CHO cell line exhibiting high expression of rhActivin A was isolated and production of rhActivin A was achieved using the cell line from 11-day fed-batch cultures in a 7.5 L bioreactor. The production rate was 0.22 g/L, substantially higher than those reported in previous studies. The culture supernatant of the bioreactor was used to purify rhActivin A (purity: >99%, recovery rate: 47%). The purified rhActivin A exhibited biological activity, with an EC50 of 3.893 ng/mL and a specific activity of 1.38 × 103 IU/mg. The control of process-related impurities in the purified rhActivin A was successful and met the USP recommendations for use in cell therapy. Thus, our production and purification methods were appropriate for large-scale GMP-grade rhActivin A production, which can be used for various purposes including cell therapy.

An Easy and Fast Method for Production of Chinese Hamster Ovary Cell Line Expressing and Secreting Human Recombinant Activin A.

Objective Growth factors are key elements of embryonic stem cell (ESC) research. Cell line development in eukaryotes is a time-consuming procedure which usually takes 12-18 months. Here, we report an easy and fast method with which production of Chinese hamster ovary (CHO) cells that express and secrete recombinant Activin A, as a major growth factor in endo/mesoderm differentiation of embryonic stem cells is achieved within 3-4 weeks. Materials and Methods In this experimental study, we cloned human Activin A into the pDONR/Zeo gateway entry vector using the BP reaction. Activin A was subcloned next into the pLIX_403 and pLenti6.3/TO/V5-DEST destination vectors by the LR reaction. The result was the production of constructs with which 293T cells were finally transfected for virus production. CHO cells were transduced using viral particles to produce a cell line that secretes the His6- Activin A fusion protein. Results We developed a quick protocol which saves up to 3-4 weeks of time for producing recombinant proteins in CHO cells. The recombinant cell line produced 90 mg/L of functional Activin A measured in human ESC line Royan H5 (RH5), during in vitro differentiation into meso-endoderm and definitive endoderm. ConclusionOur results showed no significant differences in functionality between commercial Activin A and the one produced using our novel protocol. This approach can be easily used for producing recombinant proteins in CHO.

A Novel Signal Peptide Derived from Bacillus Licheniformis α-Amylase Efficiently Targets Recombinant Human Activin A to the Periplasm of Escherichia coli

Human activin A is a member of the transforming growth factor-β superfamily consists of two similar beta subunits. Activin A is expressed by different cells and displays numerous biological activities such as control of neuronal cell proliferation and differentiation, promotion of neuronal survival in the body. Therefore, recombinant production of activin A is beneficial because it can be used to treat many neurodegenerative diseases such as Alzheimer's and Parkinson diseases. In this study E. coli as a cheap and fast-growing host was selected to produce recombinant human activin A. As cytoplasmic expression of human activin A with complex structure and disulfide bonds produces inclusion bodies, so periplasmic expression of it can be beneficial. Therefore, we used modified Iranian B. licheniformis α-amylase signal peptide as a new signal peptide in order to translocate the recombinant activin A through the inner membrane. In this study human pro-activin A cDNA and signal sequence were cloned in pET21b vector and resulting vector transformed into the two strains of E. coli BL21. SDS-PAGE and western blot techniques were used to confirm recombinant activin A expression. Finally, our results indicated that the signal peptide used in this study was effective for secretion of activin A into the periplasmic space of E. coli.

Metaphase II oocytes from human unilaminar follicles grown in a multi-step culture system.

Can complete oocyte development be achieved from human ovarian tissue containing primordial/unilaminar follicles and grown in vitro in a multi-step culture to meiotic maturation demonstrated by the formation of polar bodies and a Metaphase II spindle? Development of human oocytes from primordial/unilaminar stages to resumption of meiosis (Metaphase II) and emission of a polar body was achieved within a serum free multi-step culture system. Complete development of oocytes in vitro has been achieved in mouse, where in vitro grown (IVG) oocytes from primordial follicles have resulted in the production of live offspring. Human oocytes have been grown in vitro from the secondary/multi-laminar stage to obtain fully grown oocytes capable of meiotic maturation. However, there are no reports of a culture system supporting complete growth from the earliest stages of human follicle development through to Metaphase II. Ovarian cortical biopsies were obtained with informed consent from women undergoing elective caesarean section (mean age: 30.7 ± 1.7; range: 25-39 years, n = 10). Laboratory setting. Ovarian biopsies were dissected into thin strips, and after removal of growing follicles were cultured in serum free medium for 8 days (Step 1). At the end of this period secondary/multi-laminar follicles were dissected from the strips and intact follicles 100-150 μm in diameter were selected for further culture. Isolated follicles were cultured individually in serum free medium in the presence of 100 ng/ml of human recombinant Activin A (Step 2). Individual follicles were monitored and after 8 days, cumulus oocyte complexes (COCs) were retrieved by gentle pressure on the cultured follicles. Complexes with complete cumulus and adherent mural granulosa cells were selected and cultured in the presence of Activin A and FSH on membranes for a further 4 days (Step 3). At the end of Step 3, complexes containing oocytes >100 μm diameter were selected for IVM in SAGE medium (Step 4) then fixed for analysis. Pieces of human ovarian cortex cultured in serum free medium for 8 days (Step 1) supported early follicle growth and 87 secondary follicles of diameter 120 ± 6 μm (mean ± SEM) could be dissected for further culture. After a further 8 days, 54 of the 87 follicles had reached the antral stage of development. COCs were retrieved by gentle pressure from the cultured follicles and those with adherent mural granulosa cells (n = 48) were selected and cultured for a further 4 days (Step 3). At the end of Step 3, 32 complexes contained oocytes >100 μm diameter were selected for IVM (Step 4). Nine of these complexes contained polar bodies within 24 h and all polar bodies were abnormally large. Confocal immuno-histochemical analysis showed the presence of a Metaphase II spindle confirming that these IVG oocytes had resumed meiosis but their developmental potential is unknown. This is a small number of samples but provides proof of concept that complete development of human oocytes can occur in vitro. Further optimization with morphological evaluation and fertilization potential of IVG oocytes is required to determine whether they are normal. The ability to develop human oocytes from the earliest follicular stages in vitro through to maturation and fertilization would benefit fertility preservation practice. Funded by MRC Grants (G0901839 and MR/L00299X/1). No competing interests.

Activin A secreted by human mesenchymal stem cells induces neuronal development and neurite outgrowth in an in vitro model of Alzheimer's disease: neurogenesis induced by MSCs via activin A.

Alzheimer's disease (AD) is characterized by progressive loss of memory in addition to cortical atrophy. Cortical atrophy in AD brains begins in the parietal and temporal lobes, which are near the subventricular zone (SVZ). The aim of this study was to activate the neurogenesis in the SVZ of AD brains by human mesenchymal stem cells (hMSCs). Neural stem cells (NSCs) were isolated from SVZ of 4-month-old 5XFAD mice. Co-culture of hMSCs with SVZ-derived NSCs from 5XFAD mice induced neuronal development and neurite outgrowth. To examine the inducing factor of neurogenesis, human cytokine array was performed with co-cultured media, and revealed elevated release of activin A from hMSCs. Also, we confirmed that the mRNA levels of activin A and activin receptor in the SVZ of 5XFAD mice were significantly lower than normal mice. Treatment of human recombinant activin A in SVZ-derived NSCs from 5XFAD mice induced neuronal development and neurite outgrowth. These data suggest that use of hMSCs and activin A to recover neurogenesis in future studies of cortical regeneration to treat AD.

MiR-125b Regulates Primordial Follicle Assembly by Targeting Activin Receptor Type 2a in Neonatal Mouse Ovary.

The establishment of the primordial follicle pool is crucial for fertility in mammalian females, and the interruption of overall micro-RNA production byDicer1conditional knockout in the female reproductive system results in infertility. However, there are few reports about the functions of individual micro-RNA in regulating primordial follicle assembly. The present study aimed to investigate the function of miR-125b, which is conserved and preferentially expressed in mammalian ovary during primordial follicle assembly. Detection of miR-125b in the developing mouse ovaries by real-time PCR and in situ hybridization showed that it was highly expressed perinatally and specifically located in the ovarian somatic cells. MiR-125b overexpression blocked the process of primordial follicle assembly in cultured newborn mouse ovaries, while its knockdown promoted this process. Further studies showed that miR-125b regulated the activin/Smad2 signaling in neonatal mouse ovary by directly targeting the 3'-untranslated region of activin receptor type 2a (Acvr2a). Overexpression of miR-125b in neonatal mouse ovary suppressed theAcvr2aprotein level, attenuating activin/Smad2 signaling, while knockdown of miR-125b showed the opposite effects. In addition, recombinant human activin A (rh-ActA) down-regulated miR-125b in the neonatal mouse ovary. Overexpression of miR-125b attenuated the promoting effects of rh-ActA on primordial follicle assembly. Taken together, these data suggest that miR-125b blocks the process of primordial follicle assembly, and miR-125b may play this role by regulating the expression ofAcvr2ain the activin/Smad2 signaling pathway.

93 DEVELOPMENT OF BOVINE PRE-IMPLANTATION EMBRYOS IS ALTERED BY ADDITION OF ACTIVIN AND CONNECTIVE TISSUE GROWTH FACTOR FROM DAYS 5 TO 7 AFTER FERTILIZATION

The reproductive tract secretes bioactive molecules collectively known as embryokines that can regulate embryonic growth and development. Here we tested actions of two molecules that are highly expressed in the endometrium for actions to modify development of bovine embryos. The molecules tested were activin and connective tissue growth factor (CTGF), and endpoints were percentage of fertilized oocytes becoming blastocysts and number of inner cell mass (ICM) and trophectoderm (TE) cells in Day 7 blastocysts. Bovine embryos produced in vitro from slaughterhouse ovaries were cultured in a serum-free culture medium. On Day 5 of culture, culture drops were supplemented with vehicle (control), human recombinant activin or CTGF (10–11, 10–10, or 10–9 M). On Day 7, blastocysts (n = 202) were collected and labelled with a nuclear dye (Hoescht 33342) and a TE cell marker (anti-CDX2). Statistical analysis was performed using the GLM procedure of SAS. Results are shown as least squares means ± s.e.M. The percentage of putative zygotes becoming a blastocyst on Day 7 was 28.4 ± 1.5% for control embryos; 32.2 ± 1.5%, 30.7 ± 1.5%, and 33.1 ± 1.5% for embryos cultured with 10–11, 10–10, and 10–9 M activin, respectively; and 27.8 ± 1.5%, 25.1 ± 1.5%, and 28.4 ± 1.5% for embryos cultured with 10–11, 10–10, and 10–9 M CTGF, respectively. Activin increased the proportion of putative zygotes becoming a blastocyst when added at 10–9 M (P = 0.0321) and tended to have the same effect at 10–11 M (P = 0.0898). There was no effect of any concentration of CTGF on development of putative zygotes to blastocyst on Day 7. There was no effect of treatment on total cell number or number of TE or of activin on ICM cell number or TE : ICM ratio. However, CTGF increased (P = 0.0011) the number of ICM (40.1 ± 1.5, 46.2 ± 1.4, 46.5 ± 1.4, and 56.3 ± 1.4 for control and 10–11, 10–10, and 10–9 M CTGF, respectively). CTGF also reduced (P = 0.0319) the TE : ICM ratio. Values were 2.8 ± 0.2 for control and 2.1 ± 0.2, 1.9 ± 0.2, and 1.6 ± 0.2 for 10–11, 10–10, and 10–9 M CTGF, respectively. Results indicate that activin and CTGF can affect embryo development. In particular, activin increases competence of embryos to develop to the blastocyst stage and CTGF affects blastocyst differentiation. Support was provided by NIH R03 HD080855.

Inhibition of Phosphatase and Tensin Homologue (PTEN) in Human Ovary In Vitro Results in Increased Activation of Primordial Follicles But Compromises Development of Growing Follicles

The overwhelming majority of human ovarian follicles exist as a quiescent population from fetal life until puberty. Only a small number of follicles from this dormant population are recruited, undergo development, go on to complete growth, and release a mature fertilizable oocyte. The phosphoinositide 3-kinase (PI3K)–protein kinase B (Akt) signaling pathway has been identified as a key mechanism involved in the maintenance of follicle growth and loss. A number of growth factors stimulate PI3K to promote phosphorylation of Akt and downstream transcription factors including the forkhead winged helix box O1 (FOXO1); this results in follicle survival and activation of growth. These events are reversed by the action of phosphatase and tensin homolog (PTEN). In murine models, the effect of PTEN can be inhibited by the vanadate derivative, dipotassium bisperoxo (5-hydroxypyridine-2-carboxyl) oxovanadate (V) (bpV(HOpic), and thereby promote the downstream phosphorylation of Akt. Previous studies suggest that PTEN inhibitors could be used to generate mature oocytes in women whose oocyte reserve is impaired because of illness or treatment. There are few or no data on the response of human follicles to bpV(HOpic) in vitro. It is not known whether selective promotion of the PI3K pathway by pharmacological inhibition of PTEN in vitro would promote initiation of growth in quiescent human ovarian follicles within tissue fragments and could provide a population of biopsy-derived growing secondary follicles of sufficient quality for in vitro maturation. The aim of this study was to investigate the effect of bpV(HOpic), a reversible inhibitor of PTEN, on the activation, survival, and development of human ovarian follicles in vitro. Ovarian cortical tissue was obtained by biopsy from a total of 17 adult women aged 23 to 46 years. Fragments of the biopsied tissue were cultured for 24 hours in control medium (n = 128) or medium supplemented with 1 μM bpV(HOpic (n = 146). Media in both cultures were then replaced with control medium, and tissues were incubated for a further 5 days. After the initial 24-hour culture, half of the tissue fragments from both groups were fixed, and phosphorylated Akt was quantified by Western blot analysis. Following 6 days of incubation, tissue fragments were examined under light microscopy, and any secondary follicles 100 μm in diameter or greater were isolated. Then, follicles isolated from tissue fragments were cultured individually in control medium supplemented with 100 ng/mL recombinant human activin A. Tissue fragments without detectable follicles or with only unilaminar follicles were fixed and processed for histological and immunohistochemical analysis. Microscopic examination showed that after 6 days incubation, initiation of follicle growth had occurred in both treatment groups, but significantly more follicles progressed to the secondary stage of development in the presence of 1 bpV(HOpic) than in the control (31% vs 16%; P < 0.05). Increased activation of the PI3K pathway in tissue exposed to bpV(HOpic) was confirmed by an increase in Akt phosphorylation and nuclear export of FOXO3. However, isolated and cultured secondary follicles treated with bpV(HOpic) exhibited limited growth and reduced survival compared with follicles from control fragments (P < 0.05). These data demonstrate that inhibition of PTEN with bpV(HOpic) promotes activation and development of isolated follicles to the secondary stage, as in rodents, but severely compromises their continued growth and survival.

Insulin like growth factor binding protein 7 (IGFBP7) expression is linked to poor prognosis but may protect from bone disease in multiple myeloma.

BackgroundInsulin like growth factor binding protein 7 (IGFBP7) is a secreted protein binding insulin like growth factor 1 (IGF-1), insulin, vascular endothelial growth factor A (VEGFA), and activin A. It antagonizes bone morphogenetic proteins and is involved in the tumour propagation of solid as well as haematological malignancies. Its role in multiple myeloma (MM) is not defined so far. We therefore aim here to investigate its prognostic and pathophysiological role in MM.MethodsThe clinical significance of IGFBP7 gene expression was investigated by gene expression profiling in two independent cohorts (n = 948) of newly-diagnosed MM patients. Methylation of the IGFBP7 promoter was analysed by pyrosequencing and treatment of MM cell lines with 5-aza-2-deoxycytidine. The impact of IGFBP7 on MM cells was studied by CCK-8 assay, BrdU assay and flow cytometry, respectively. IGFBP7 expression in bone marrow stromal cells (BMSCs) was studied by quantitative RT-PCR. For osteoblast development, immortalized and primary human BMSCs were cultured in osteogenic differentiation medium for 7–14 days in the presence of recombinant human IGFBP7 and/or activin A.ResultsMedian IGFBP7 expression is significantly lower in CD138-purified plasma cells from individuals with MGUS and MM, compared to normal bone marrow plasma cells. IGFBP7 gene expression in MM cells is regulated by methylation, shown by pyrosequencing and exposure to demethylating agents (5-aza-2-deoxycytidine). High expression of IGFBP7 in MM cells is associated with adverse survival in two independent cohorts of 247 and 701 newly-diagnosed MM patients treated with high-dose therapy and autologous stem cell transplantation. IGFBP7 is associated with prognostically adverse chromosomal aberrations (t(4;14) and gain of 1q21), MMSET expression, and higher myeloma cell proliferation. In vitro, IGFBP7 overcomes activin A induced osteoblast suppression and promotes osteogenesis. MM cells downregulate IGFBP7 in stromal cells, possibly contributing to the osteoblast suppression found in MM. Conversely, higher IGFBP7 expression is associated with a lower probability of myeloma bone disease.ConclusionsOur data indicate that IGFBP7 expression is a marker for a specific methylation pattern in myeloma, linked to translocation t(4;14) associated MMSET expression, showing clinical features of adverse prognosis with absence of myeloma bone disease.Electronic supplementary materialThe online version of this article (doi:10.1186/s13045-014-0105-1) contains supplementary material, which is available to authorized users.

High Levels Production of Recombinant Human Activin A—Effect upon &amp;lt;i&amp;gt;in Vivo&amp;lt;/i&amp;gt; Follicle Stimulation

Activin plays an important role in numerous physiological processes such as cell differentiation and remodeling, regeneration and repair of tissues from various organs, angiogenesis, morphogenesis of glandular organs, pluripotency and differentiation of stem cells, cell adhesion and apoptosis. It participates in reproductive processes like embryogenesis, in the expression of Follicle Stimulating Hormone and Luteinizing Hormone and maturation of ovarian follicles and therefore has application in the area of reproduction of vertebrates. Given the economic importance of activin, we develop an efficient and economical method for the production of recombinant human activin A (rACT), using as expression system the yeast Pichia pastoris. rACT showed biological activity as it induced, on submicromolar dose, the increase of ovarian mass and the ovulation process in a mammal model.

Inhibition of phosphatase and tensin homologue (PTEN) in human ovary in vitro results in increased activation of primordial follicles but compromises development of growing follicles.

In the mammalian ovary a small number of follicles are steadily recruited from the quiescent pool to undergo development. Follicle loss, maintenance and growth are strictly controlled by complex molecular interactions including the phosphoinositide 3-kinase (PI3K)-protein kinase B (Akt) signalling pathway. Stimulation of PI3K promotes phosphorylation of Akt resulting in follicle survival and activation of growth whereas this pathway is suppressed by the actions of the phosphatase and tensin homologue (PTEN). The aim of this study was to determine the effect of dipotassium bisperoxo(5-hydroxypyridine-2-carboxyl)oxovanadate (bpV), a reversible inhibitor of PTEN, on the activation, survival and development of human ovarian follicles in vitro. Biopsied ovarian tissue fragments were obtained from 17 women aged 23–46 years and exposed to 1 µM bpV(HOpic) (n = 146) or control medium (n = 128) for 24 h. Media were then replaced with control medium and all tissue incubated for a further 5 days. Ovarian tissue from each treatment group was fixed after the initial 24 h culture period and phosphorylated Akt was quantified by western blotting. After 6 days incubation all tissue fragments were inspected under light microscopy and any secondary follicles ≥100 µm isolated. Isolated follicles were cultured individually in control medium supplemented with 100 ng/ml recombinant human activin A. Tissue fragments without follicles suitable for isolation were fixed and processed for histological and immunohistochemical analysis. During 6 days culture, follicle activation occurred in tissue samples from both treatment groups but with significantly more follicles progressing to the secondary stage of development in the presence of 1 µM bpV(HOpic) compared with control (31 versus 16%; P < 0.05). Increased activation was associated with increased Akt phosphorylation and increased nuclear export of FOXO3. However isolated and cultured follicles that had been exposed to bpV(HOpic) showed limited growth and reduced survival compared with follicles from control fragments (P < 0.05). This study demonstrates that inhibition of PTEN with bpV(HOpic) affects human ovarian follicle development by promoting the initiation of follicle growth and development to the secondary stage, as in rodent species, but severely compromises the survival of isolated secondary follicles.

In vitro developmental competence of prepubertal goat oocytes cultured with recombinant activin-A

The present study was designed to evaluate the effect of activin-A during the in vitro oocyte maturation (IVM) and in vitro embryo culture (IVC) on nuclear maturation, blastocyst yield and blastocyst quality of prepubertal goat oocytes. In Experiment 1, three groups of oocytes were used during the IVM of prepubertal goat oocytes to determine the optimal concentration of recombinant human activin-A added to the maturation medium. Cumulus–oocyte complexes were matured in an IVM medium containing 0, 10 and 100 ng/ml (groups A0, A10 and A100), fertilized and in vitro cultured using standard procedures. In Experiment 2, the addition of 10 ng/ml activin-A at IVM (A10A0), IVC (A0A10) or IVM+IVC (A10A10) was studied and compared with the control group (A0A0). Results of the first experiment demonstrated that the addition of activin-A yielded similar percentages of maturation (⩽71.0%) and blastocyst formation rates (⩽24.9%) than the control group (A0). Experiment 2 showed that exposure of prepubertal goat oocytes to an IVC medium containing 10 ng/ml activin-A (A0A10) significantly increased the rates of development to the blastocyst stage, as compared with the control group (A0A0) (19.5±2.21% v. 13.1±2.37%, respectively; P<0.05). With regard to the blastocyst quality, total number of cells, inner cell mass (ICM) and trophectoderm of prepubertal goat embryos produced in the presence of activin-A did not differ significantly among experimental groups. In summary, these results indicate that supplementation of the IVC medium with activin-A enhances embryo development of prepubertal goat oocytes.

Activin A Suppresses Osteoblast Mineralization Capacity by Altering Extracellular Matrix (ECM) Composition and Impairing Matrix Vesicle (MV) Production

During bone formation, osteoblasts deposit an extracellular matrix (ECM) that is mineralized via a process involving production and secretion of highly specialized matrix vesicles (MVs). Activin A, a transforming growth factor-β (TGF-β) superfamily member, was previously shown to have inhibitory effects in human bone formation models through unclear mechanisms. We investigated these mechanisms elicited by activin A during in vitro osteogenic differentiation of human mesenchymal stem cells (hMSC). Activin A inhibition of ECM mineralization coincided with a strong decline in alkaline phosphatase (ALP(1)) activity in extracellular compartments, ECM and matrix vesicles. SILAC-based quantitative proteomics disclosed intricate protein composition alterations in the activin A ECM, including changed expression of collagen XII, osteonectin and several cytoskeleton-binding proteins. Moreover, in activin A osteoblasts matrix vesicle production was deficient containing very low expression of annexin proteins. ECM enhanced human mesenchymal stem cell osteogenic development and mineralization. This osteogenic enhancement was significantly decreased when human mesenchymal stem cells were cultured on ECM produced under activin A treatment. These findings demonstrate that activin A targets the ECM maturation phase of osteoblast differentiation resulting ultimately in the inhibition of mineralization. ECM proteins modulated by activin A are not only determinant for bone mineralization but also possess osteoinductive properties that are relevant for bone tissue regeneration.

WNT3 Is a Biomarker Capable of Predicting the Definitive Endoderm Differentiation Potential of hESCs

Generation of functional cells from human pluripotent stem cells (PSCs) through in vitro differentiation is a promising approach for drug screening and cell therapy. However, the observed large and unavoidable variation in the differentiation potential of different human embryonic stem cell (hESC)/induced PSC (iPSC) lines makes the selection of an appropriate cell line for the differentiation of a particular cell lineage difficult. Here, we report identification of WNT3 as a biomarker capable of predicting definitive endoderm (DE) differentiation potential of hESCs. We show that the mRNA level of WNT3 in hESCs correlates with their DE differentiation efficiency. In addition, manipulations of hESCs through WNT3 knockdown or overexpression can respectively inhibit or promote DE differentiation in a WNT3 level-dependent manner. Finally, analysis of several hESC lines based on their WNT3 expression levels allowed accurate prediction of their DE differentiation potential. Collectively, our study supports the notion that WNT3 can serve as a biomarker for predicting DE differentiation potential of hESCs.

Low level of activin A secreted by fibroblast feeder cells accelerates early stage differentiation of retinal pigment epithelial cells from human pluripotent stem cells

Human pluripotent stem cells (hPSC) differentiated to retinal pigment epithelial cells (RPE) provide a promising tool for cell replacement therapies of retinal degenerative diseases. The in vitro differentiation of hPSC-RPE is still poorly understood and current differentiation protocols rely on spontaneous differentiation on fibroblast feeder cells or as floating cell aggregates in suspension. The fibroblast feeder cells may have an inductive effect on the hPSC-RPE differentiation, providing variable signals mimicking the extraocular mesenchyme that directs the differentiation in vivo. The effect of the commonly used fibroblast feeder cells on the hPSCRPE differentiation was studied by comparing suspension differentiation in standard RPEbasic (no bFGF) medium to RPEbasic medium conditioned with mouse embryonic (mEF-CM) and human foreskin (hFF-CM) fibroblast feeder cells. The fibroblast secreted factors were found to enhance early hPSC-RPE differentiation. The onset of pigmentation was faster in the conditioned media (CM) compared to RPEbasic for both human embryonic (hESC) and induced pluripotent (iPSC) stem cells, with the first pigments appearing around two weeks of differentiation. After four weeks of differentiation, CM conditions consistently contained higher number of pigmented cell aggregates. The ratio of PAX6 and MITF positive cells was quantified to be clearly higher in the CM conditions, with mEFCM containing most positive cells. The mEF cells were found to secrete low levels of activin A growth factor that is known to regulate eye field differentiation. As RPEbasic was supplemented with corresponding, low level (10 ng/ml) of recombinant human activin A, a clear increase in the hPSC-RPE differentiation was achieved. Thus, inductive effect provided by feeder cells was at least partially driven by activin A and could be substituted with a low level of recombinant growth factor in contrasts to previously reported much higher concentrations.

Activin A Suppresses Induced Formation of Neuroectoderm in Colonies of Parthenogenetic Stem Cells In Vitro

We studied the effect of recombinant human activin A on induced neuroectoderm formation in colonies of human parthenogenetic SC in the absence of feeder cells. It was found that pretreatment of human parthenogenetic SC with activin A suppressed subsequent neural induction. Activin A in a concentration of 10 ng/ml significantly decreased transcriptional activity of genes required for neuroectoderm formation. At the same time, activin A in a concentration of 20 ng/ml increased the expression of pluripotency genes and completely inhibited the formation of structures in vitro reproducing the neural tube of the developing embryo. These findings attest to prolonged effect of activin A as an inhibitor of neuroectodermal differentiation.

296 PRODUCTION OF HEMIZYGOUS AND HOMOZYGOUS EMBRYONIC STEM CELL-DERIVED NEURAL PROGENITOR CELLS FROM THE TRANSGENIC ALZHEIMER GÖTTINGEN MINIPIG

Alzheimer’s disease is the most prevalent cause of dementia and afflicts ∼26 million people worldwide. There are currently no cures for this disease. Production of in vitro models of the disease would be extremely useful for studying disease mechanisms and for potential screening of novel drugs. In this study we produced 2 hemizygote and 2 homozygote embryonic stem cell-derived neural progenitor cell lines from Day 8 transgenic blastocysts carrying a human gene linked to early-onset Alzheimer’s disease [Swedish mutation of the amyloid precursor protein (hAPPsw)]. Following onset of spontaneous oestrus, a mating of hAPPsw± × hAPPsw± Göttingen transgenic progeny was performed. Eight days after the first of 2 matings, embryos were flushed from the tip of both cornuas of the gilt under surgical anaesthesia. A total of 6 blastocysts were obtained and 7 corpora lutei recorded. Blastocysts were transported for 4 h in porcine zygote medium 3 (PZM-3) in hypoxic, humidified conditions at 39°C to the cell laboratory. Compact epiblasts were mechanically isolated from the embryo using insulin needles and cultured on inactivated mouse embryonic fibroblasts in embryonic stem cell medium, supplemented with 20 ng mL–1 human recombinant basic fibroblast growth factor (Prospec) and 20 ng mL–1 human recombinant Activin A (Prospec), for a period of 5 days in hypoxic conditions at 39°C. Five of the 6 epiblasts expanded to form embryonic stem-cell-like outgrowth colonies. These were cut into small colonies and plated on MS5 murine stromal cells to induce spontaneous neural differentiation in DMEM medium containing 15% knockout serum replacement. Neuronal rosette-like structures were identified from Day 10 of differentiation onward. Six rosette structures were mechanically isolated from 4 outgrowths and plated in serum-free conditions on Matrigel-coated dishes. Two of the 6 lines failed to proliferate beyond passage 2. The 4 remaining cell lines have currently been cultured to passage 7. These lines were analysed at passage 5 by comparative real-time PCR and found to be positive for the neural progenitor markers VIMENTIN, SOX2, NESTIN PAX6, MUSASHI; other neural markers BETAIIITUBULIN and NCAM; and the astrocyte marker, GFAP. These lines were also subjected to analysis by immunocytochemistry and found to express SOX2, VIMENTIN, and NESTIN. Further genotyping by comparative real-time PCR using primers designed to target the hAPPsw gene revealed that 2 lines carried a single copy of hAPPsw and 2 lines carried 2 copies of hAPPsw. The expression levels of the hAPPsw transgene in these cell lines were determined using quantitative PCR. These cell lines are currently being investigated for their ability to differentiate into cholinergic neurons and for their expression of hyperphosphorylated TAU and β-Amyloid secretion. These cell lines will be potentially relevant for the in vitro study of amyloid precursor protein accumulation in neural cells and its role in cell death, as well as for potential screening of novel drugs for Alzheimer’s disease.