Introduction Porcine embryonic stem cells (pESCs) derived from cloned embryos might be a useful animal model in biomedical research, however, establishment of cloned pESCs is difficult by its incomplete nuclear reprogramming. Here, we report the improved development competence of porcine cloned embryos by vitamin C (VC) supplement to establish the pESCs. Materials and Methods Slaughterhouse-derived oocytes were in vitro matured for 44h and parthenogenetic and cloned embryos were produced using matured oocytes. Both of embryos were cultured for 6 days in PZM-5 media and development rates were examined. Four different concentration of VC (0, 25, 50, 100, and 200 μg/ml) was supplemented in IVM and IVC media and preimplantation developments in the 5 groups were compared in both of embryos Results and Discussion In the cleavage rates of IVM group, significantly higher rate was shown in 50 mg/ml group than other groups (84.5 ± 0.6% vs. 69.8 ± 5.5, 75.7 ± 1.8, 80.4 ± 0.2, 72.4 ± 0.1%; P<0.05), respectively. Significantly higher rates of blastocyst development also were shown in 50 mg/ml group than other groups (27.0 ± 2.0% vs. 20.4 ± 1.4, 22.1 ± 1.3, 23.7 ± 1.2, 19.6 ± 1.3%; P<0.05), respectively. In the cleavage rate of IVC group, non-significantly different with each group (84.0 ± 1.3, 86.7 ± 1.0, 88.4 ± 1.4, 76.7 ± 3.0, 64.6 ± 4.4; P<0.05). In the blastocyst rate of IVC group, significantly higher rate was shown in 25mg/ml and 50 mg/ml group than other groups (22.3 ± 1.7, 23.8 ± 1.7% vs. 19.1 ± 1.3, 15.9 ± 1.0, 5.8 ± 1.5%; P<0.05) In conclusion, supplement of 50μg/ml of VC in IVM and IVC media enhanced the development of porcine parthenogenetic embryos and these results will be a helpful information in the development of porcine cloned embryos and derivation of its embryonic stem cells.

The mesenchymal stem cells (MSC) has been investigated as a source of stem cell therapy to replace and treat damaged cells. Human endometrial epithelial and stromal cells was isolated from hysterectomy tissue and the direct evidence of stem/progenitor cells in the human endometrium was identified. Endometrium derived stem cells (EnMSCs) are known to have a high proliferative ability, genetic stability, lack of tumorigenicity and low immnunogenicity during long-term cultivation. Here, we aimed to identify MSC in canine endometrium and characterize its potential to differentiate into decidua cells. EnMSCs were isolated from thrown-away spayed uterus of adult canine depending on their estrus cycle, and identified by flow cytometry, immunocytochemistry and flow cytometry with MSC specific markers. We then characterized the ability of EnMSCs by the doubling-time analysis, colony-forming units and MSC differentiation assays. Isolated EnMSCs expressed stem cell specific genes (Sox2, Oct4, Nanog, MCAM, Endoglin, Susd2 and IGTB) and MSC surface markers (CD90, CD44 and CD117). EnMSCs are also differentiated into adipogenic, osteogenic and chondrogenic cells morphologically under modified conditions with the expression of lineage specific genetic markers. EnMSCs showed higher proliferation ability than canine amniotic fluid derived MSCs which were used as a positive control. EnMSCs were cultured at low density (10, 20, cells/cm2) and initiated to form small colonies of loosely-arranged cells and gradually formed large colonies of densely-packed cells which underwent self-renewal with high proliferative potential which is similar to the clonogenicity feature of human endometrium-derived stem cells. EnMSCs were then induced to differentiate into decidua cells with 0.5 mM dbcAMP. After 14 days, EnMSCs changed their morphology into the elongated and rounded shape. The induced decidual cells expressed PRL and IGFBP1 which are typically expressed in decidua cells. In conclusion, we successfully isolated and characterized MSC in the canine endometrium which differentiated into decidua cells. These results showed that endometrium may be a promising source of stem cells, and furthermore raise the possibility of canine EnMSCs as a novel hypothetical decidualisation model of infertility associated with decidualisation insufficiency and implantation failure.

To investigated the mechanism, induced pluripotent stem cells(iPSC) is important for clinical application and stem cell research. It is well known that hMAGEA2 expression pattern and effect on differentiation in embryonic stem cell but their specific role in iPS cells are unclear. The present study was schemed to understand the function of hMAGEA2 gene in iPS cells and to elucidate its characteristic. Although overexpression of hMAGEA2 in iPS cells are not different on morphology, their pluripotency and self-renewal capacity are significantly strengthened. And hMAGEA2 contributed to promote the cell cycle progression, this cell cycle changes induced proliferation acceleration. Through embryoid body formation in vitro and teratoma formation in vivo, we found that hMAGEA2 critically decreases the differentiation ability in iPS cells. Our results demonstrate that hMAGEA2 intensified the self-renewal, pluripotency, proliferation degree but efficiency of differentiaton is significantly repressed. Our findings provided that hMAGEA2 play a key role of iPS cells.

체외 배양액에 성장호르몬 및 사이토카인의 첨가는 초기배 발육 및 생산된 배반포의 질에 영향을 미칠 수 있다. 본 연구는 돼지 유도만능줄기세포(porcine induced pluripotent stem cell, piPSC)의 조정배지(conditioned medium, CM)가 돼지 난자의 체외성숙 및 단위발생 후 초기배 발육에 미치는 영향을 검토하기 위하여 수행하였다. 난자-난구세포 복합체(cumulus-oocyte complex, COC)는 0(control), 25, or 50%의 줄기세포 배양액(stem cell medium, SM) 또는 CM이 첨가된 체외성숙 배양액으로 배양하였으며, 성숙된 난자는 활성화 유도 후 같은 농도의 SM 또는 CM을 첨가한 체외배양액에서 배양하였다. 체외 성숙율은 CM-25% 그룹에서 대조구보다 유의적으로 높았으나(p<0.05), 다른 SM 또는 CM 처리구와는 차이가 없었다. 배반포 형성율은 CM-25% 그룹(29.2%)에서 대조구(20.7%), SM-50%(19.6%) 및 CM-50%(23.66%) 처리구보다 유의적으로 높았다(p<0.05). 배반포에서의 세포수 및 세포사 비율은 SM-25% 그룹이 대조구에 비하여 유의적인 차이가 나타났다(p<0.05). 난자의 질과 연관되어 있는 유전자들(Oct4, Klf4, Tert 및 Zfp42)의 발현은 CM-25% 그룹에서 대조구보다 유의적으로 증가되었다(p<0.05). 따라서 본 실험의 결과 체외성숙(IVM) 및 체외발달(IVC) 배양액에 25% 수준의 CM의 첨가는 돼지 단위발생 난자의 배발달과 난자의 질적 향상에 기여하는 것으로 사료된다.

위축돈은 정상돈에 비해 생시체중이 낮고 생후 성장과 발달도 미숙하다. 근육의 성장에 있어 muscle satellite cells(SC)의 역할에 대해 많은 연구가 진행되고 있다. 근육 내에서 줄기세포를 하는 side population(SP) 세포군이 최근 밝혀졌는데, 이 세포군은 Hoechst dye를 이용한 fluorescence-activated cell sorting(FACS)에 의해 이용하여 분리되는데, 다양한 조직(특히 근육)으로 분화되는 것으로 밝혀졌다. 위축돈과 정상돈 근육 내 SC와 SP 세포군의 숫자 및 성상을 비교분석하기 위해 semitendinosus(ST) 근육을 적출하여 SC와 SP를 분리·배양 하였다. 위축돈의 ST는 정상돈에 비해 무게가 가볍고 근섬유의 숫자와 크기도 작았다(p<0.05). 하지만 정상돈과 위축돈의 ST 근육 내 단백질과 DNA 총량은 차이가 없었다. 총 RNA 양과 DNA 농도는 정상돈의 ST 근육에서 위축돈에 비해 높게(p<0.05) 나타났다. ST 근육에서 추출된 총 세포수(yield/g)에는 정상돈과 위축돈 간 차이가 없었다. 세포의 증식률을 0, 24, 48 시간동안 두 그룹 간 차이가 없었다. 세포 배양 72시간 후 정상돈 ST 근육에서 추출된 세포의 증식률이 위축돈의 그것에 비해 높게(p<0.05) 나타났다. 정상돈 ST 근육에서 위축돈 ST 근육에 비해 SP 세포가 더 많이(p<0.05) 추출되었다. 종합해 보면, 위축돈의 근육 크기와 근섬유의 숫자가 정상돈에 비해 작고, 근육내 줄기세포의 역할을 하는 SC와 SP 세포군 또한 낮게 나타난 것은 위축자돈이 임신 기간 동안 충분한 영양을 받지 못하여 근육 내 줄기세포의 증식이 낮아졌으며, 이는 근육 내 줄기세포가 자돈의 성장과 발달에 큰 영향을 미치는 결과로 해석할 수 있다.

Spermatogenesis is initiated from spermatogonial stem cells (SSCs) that has an ability of self-renewal and unipotency to generate differentiating germ cells. The objective of this study is to develop the simple method for derivation of SSCs using non-sorting of both spermatogonia and feeder cells. Simply uncapsulated mouse testes were treated with enzymes followed by surgical mincing, and single cells were cultured in stempro-34TM cell culture media at 37℃. After 5 days of culture, aciniform of SSC colony was observed, and showed a strong alkaline phosphatase activity. Molecular characterization of mouse SSCs showed that most of the mouse SSC markers such as integrin α6 and β1, CD9 and Stra8. In addition, pluripotency embryonic stem cell (ESC) marker Oct4 were expressed, however Sox2 expression was lowered. Interestingly, expression of SSC markers such as Vasa, Dazl and PLZF were stronger than mouse ESC (mESC). This data suggest that generated mouse SSCs (mSSCs) in this study has at least similar biomarkers expression to mESC and mSSCs derived from other study. Immunocytochemistry using whole mSSC colony also confirmed that mSSCs generated from this study expressed SSC specific biomarkers such as c-kit, Thy1, Vasa and Dazl. In conclusion, mSSCs from 5 days old mouse testes were successfully established without sorting of spermatogonia, and this cells expressed both mESC and SSC specific biomarkers. This simple derivation method for mSSCs may facilitate the study of spermatogenesis.

Embryonic stem cell-preconditioned microenvironment is important for cancer cells properitities by change cell morphology and proliferation. This microenvironment induces cancer cell reprogramming and results in a change in cancer cell properties such as differentiation and migration. The cancer microenvironment affects cancer cell proliferation and growth. However, the mechanism has not been clarified yet. Using the ES-preconditioned 3-D microenvironment model, we provide evidence showing that the ES microenvironment inhibits proliferation and reduces oncogenic gene expression. But ES microenvironment has no effect on telomerase activity, cell viability, cellular senescence, and methylation on Oct4 promoter region. Furthermore, methylation of Nanog was increase on ES-preconditioned microenvironment and supports results that no difference on RNA expression levels. Taken together, these results demonstrated that in the ES-preconditioned 3-D microenvironment is a crucial role for cancer cell proliferation not senescence.

Though hydrogen peroxide (H₂O₂) causes a deleterious effect to cells with its reactive oxygen species resulting in cell death, S-allyl cysteine (SAC, a bioactive organosulfur compound of aged garlic extract) has been known to have a cytoprotective effect. Few reported profiles of gene expression of H₂O₂ and SAC treated human cord blood derived mesenchymal stem cells (MSC). This study revealed changes in the profile of twenty-one genes grouped by oxidative stress, antioxidant, cell death, anti-apoptosis and anti-aging by quantitative real time PCR. A concentration of 100μM of SAC or 50μM of H₂O₂ was applied to MSC which show moderate growth and apoptosis pattern. H₂O₂ treatment enhanced expression of eleven genes out of twenty-one genes compared with that of control group, on the contrary SAC suppressed expression of eighteen genes out of twenty-one genes except C ros oncogene. SAC decreased expression of oxidative stress genes such as SOD1, CAT and GPX. These results seemed consistent with reports which elucidated over expression of NF-kB by H2O2, and suppression of it by SAC. This study will confer basic information for further experiments regarding the effects of SAC on gene levels.

Althogh Spermatogonial stem cells (SSCs) are widely studied in mice, study of pig SSCs is not sufficient for the isolation, long-term culture, and characterization. To identify the effect of growth factor in cultured pig SSC, newly generated pSSCs like cell from neonatal 5days porcine testis were cultured and investigated for the pSSCs like cell formation. Glial derived neurotrophic gactor (GDNF), fibroblast growth factor (FGF), leukemia inhibitory factor (LIF), and epidermal growth factor (EGF) were applied to culture media to identify the pSSC like cell growth and stem cell formation. The criteria for the determining of stem cell characters, morphology, number of colonies, putative stem cell marker were analysed by microspic, polymerase chain reaction (PCR) and immunocytochemistry (ICC) methods. Most of the pSSCs like cells were formed approximately 100 μm size with sphere shape. Most of the feeder cells were highly dependent on FGF that feeder cells were not stably attached on plate without FGF and colony formation of pSSC was not observed consequently. Immunocyto chemistry data revealed that this cells expressed the ubiquitin-C-terminal hydrolase 1 (UCHL-1, PGP9.5) and Dolichos Biflorus Agglutinin (DBA) in addition of 20 ng/ml EGF, 10 ng/ml FGF, 10 ng/ml GDNF, 10 U3/ml LIF. In addition, Alkaline Phosphatase ()was positive in all period of culture. This study suggest that various growth factorsinp SSC culture system is important to regulate and maintain the pSSC. In conculsion, although the precise role of growth factor in pSSC proliferation need to be clarified, combination of growth factor might be critical in order to derivation and proliferation of neonatal pSSCs and spermatogenesis.

Pig embryonic stem cells (ESC) has been suggested to become important animal model for therapeutic cloning using embryonic stem cells derived by somatic cell nuclear transfer (SCNT). However, the quality of cloned embryo and derivation rate of cloned blastocyst has been presented limits for derivation of cloned embryonic stem cell. In this study, we have tried to overcome these problems by aggregating porcine embryos. Zonafree reconstructed SCNT Embryos were cultured in micro-wells singularly (non-aggregated group) or as aggregates of three (aggregated groups) at the four cell stage. Embryo quality of the cloned embryos and attachment on feeder layer rate significantly increased in the aggregates. The aggregation of pig SCNT embryos at the four-cell stage can be a useful technique for improving the quality of pig cloned blastocyst and improvement in the percentage of attachment on the feeder layer of cloned embryos. * This work was supported by the BioGreen 21 Program (PJ0081382011), Rural Development Administration, Republic of Korea.

Adipose tissue-derived mesenchymal stem cells (ASCs) are very interesting in several laboratory animals and humans because they are easy to harvest and expand to generate millions of cells from a small quantity of fat. ASCs are known as useful materials for clinical applications in human cell therapy and as a donor cell in somatic cell nuclear transfer (SCNT). Here, we investigated if 1) minipig ASCs can be isolated, self-renewed and differentiated into multiple tissue lineages, 2) ASCs can be a suitable donor cell type for generation of cloned pig. In order to isolate ASC, adipose tissues were collected from inguinal region of a 6-year-old female minipig. The ASCs were attached to the culture dish with a fibroblast-like morphology. They expressed cell-surface marker characteristics of stem cell, underwent osteogenic, adipogenic, myogenic, neurogenic and chondrogenic differentiation when exposed to specific differentiation-inducing conditions. To investigate its potential as donor cell for cloning, we respectively carried out SCNT using ASC, adult skin fibroblast (ASF) and fetal fibroblast (FF) derived from same minipig. The ratio of blastocysts to 2-cell embryos and total cell number of blastocysts were monitored as experimental parameters. In results, cleavage and developmental competence to blastocysts rate showed no significant difference among the three groups. On the other hand, total cell numbers of blastocysts derived from ASC and FF were significantly higher than in ASF (89±7.9 and 105±5.5 vs. 57.5±5.2, respectively). Our results demonstrated that ASC have potential compared to ASF and FF in terms of the in vitro development and blastocyst formation ability. In further study, we will investigate the in vivo developmental ability of ASC as donor cell for pig cloning. * This study was supported by IPET (#311011-05-1-SB010), RNL Bio (#550-20120006), Institute for Veterinary Science, the BK21 program, TS Corporation and Optifarm Solution.

Induced pluripotent stem (iPS) cells have been generated from mouse and human somatic cells by etopic expression of transcription factors. iPS cells are indistinguishable from ES cells in terms of morphology and stem cell marker expression. Moreover, mouse iPS cells give rise to chimeric mice that are competent for germline transmission. However, mice derived from iPS cells often develop tumors. Furthermore, the low efficiency of iPS cell generation is a big disadvantage for mechanistic studies. Nonviral plasmid‐based vectors are free of many of the drawbacks that constrain viral vectors. The histone deacetylase inhibitor valproic acid (VPA) has been shown to improve the efficiency of mouse and human iPS cell generation, and vitamin C (Vc) accelerates gene expression changes and establishment of the fully reprogrammed state. The MEK inhibitor PD0325901 (Stemgent) has been shown to increase the efficiency of the reprogramming of human primary fibroblasts into iPS cells. In this report, we described the generation of mouse iPS cells devoid of exogenous DNA by the simple transient transfection of a nonviral vector carrying 2A‐peptide‐linked reprogramming factors. We used VPA, Vc, and the MEK inhibitor PD0325901 to increase the reprogramming efficiency. The reprogrammed somatic cells expressed pluripotency markers and formed EBs.

Mitochondria diseases have been reported to involve structural and functional defects of complex I-V. Especially, many of these diseases are known to be related to dysfunction of mitochondrial proton-translocating NADH-ubiquinone oxidoreductase (complex I). The dysfunction of mitochondria complex I is associated with neurodegenerative disorders, such as Parkinson's disease, Huntington's disease, and Leber’s hereditary optic neuropathy (LHON). Mammalian mitochondrial proton-translocating NADH-quinone oxidoreductase (complex I) is largest and consists of at least 46 different subunits. In contrast, the NDI1 gene of Saccharomyces cerevisiae is a single subunit rotenone-insensitive NADH-quinone oxidoreductase that is located on the matrix side of the inner mitochondrial membrane. The Saccharomyces cerevisiae NDI1 gene using a recombinant adeno-associated virus vector (rAAV-NDI1) was successfully expressed in AML12 mouse liver hepatocytes and the NDI1-transduced cells were able to grow in media containing rotenone. In contrast, control cells that did not receive the NDI1 gene failed to survive. The expressed Ndi1 enzyme was recognized to be localized in mitochondria by confocal immunofluorescence microscopic analyses and immunoblotting. Using digitonin-permeabilized cells, it was shown that the NADH oxidase activity of the NDI1-transduced cells was not affected by rotenone which is inhibitor of complex I, but was inhibited by antimycin A. Furthermore, these results indicate that Ndi1 can be functionally expressed in the AML12 mouse liver hepatocytes. It is conceivable that the NDI1 gene is powerful tool for gene therapy of mitochondrial diseases caused by complex I deficiency. In the future, we will attempt to functionally express the NDI1 gene in mouse embryonic stem (mES) cell.

Somatic cell nuclear transfer (SCNT) is an efficient technique which has been successfully applied to developmental biology, and resulted in the production of offspring from various species. It offers many opportunities in basic and medical research as well as endangered species preservation. On the other hand, embryonic stem (ES) cells are useful research tools for genetic engineering and developing disease models. In previous study, we established bovine IVF embryo derived ES cell line which can be grow indefinitely as undifferentiated cell state. In this study, we compared the effect of two different age cells (bovine ES cell; JNU-ibES-05 or adult ear fibroblast cell) on in vitro developmental potential of bovine SCNT embryo. To produce SCNT embryos, the ES cells or somatic cells were dissociated and transferred into enucleated MⅡ oocytes, and cleaved reconstructed embryos were cultured in CR1aa medium containing 10% FBS, 1 ug/ml epidermal growth factor (EGF) and 1 ug/ml insulin growth factor (IGF) for 8 days. In the result, blastocyst development rate was similar between ES cell treatment group and somatic cell treatment group, 27.7% (10/36) and 28.9% (11/ 38), respectively. However, there was particular difference in development speed from day 5 post SCNT, blastocyst expanding was 1 day faster in ES cell group than in somatic cell group. This difference was analyzed by semi-quantitative RT-PCR using pluripotency, growth and cell cycle gene markers. These results demonstrated that SCNT embryo using ES cell as a donor cell has better growth potential than somatic cell, and it will be a useful tool for a transgenic animal production.

The generation of patient-specific pluripotent stem cells has the potential to accelerate the implementation of stem cells for clinical treatment of degenerative diseases. This study was to examine the in vitro neuron cell differentiation characteristics of our established human (h) iPS cells (IMR90-iPS-1~2) derived from human somatic cells. For the neuron differentiation, well grown hiPS colonies were recovered by collagenase treatment and then suspended cultured in a non-adherent bacteriological culture dish using human embryonic stem (hES) cell culture medium for 4 days. Embryoid bodies were plated and cultured in serum-free ITSFN (insulin/transferrin/selenium/fibronectin) medium for 8 days to select neural precursor cells. Then selected neuronal cells were dissociated, plated onto poly-L-ornithin/laminin coated dish at a concentration of 2 x 105 cells/cm2 and expanded in N2 medium containing 20 ng/ml bFGF, 200 ng/ml SHH and 100 ng/ml FGF-8 for 7 days. For the final differentiation step involved removing agents and culturing for 14 days in 20 ng/ml BDNF added N2 medium. In the neural precursor stage, >90% of nestin positive cells and >50% NCAM positive cells were obtained. Also, in final differentiation step, we confirmed the high percent (>80%) of mature neuron tubulin-β positive cells and approximately >20% of tyrosine hydroxylase positive cells. Also, these results were confirmed by RT-PCR. These results indicated that hiPS cells have potential to generate specific neuron differentiation and especially TH+ neuron was also can be obtained, and thus hiPS-derived neural cells might be an usable source for the study of neuro-degenerative disease.

Some tissues retain extensive regeneration potential through out adult life and remain as active sites of cell production. Various cell types present in tissues are being produced through proliferation and progressive specialization from a pool of stem cells. In this regard, adult stem cells (ASCs) are multipotent progenitor cells with an ability to proliferate in vitro and undergo extensive self-renewal and differentiation into a wide range of cell types, including adipocytes, chondrocytes, osteocytes, myocytes, cardiomyocytes and neurons. In addition, recent studies showing the abilities of ASCs in generating oocytes-like cells (OLCs) present new perspectives to understand the specification and interaction during the germ cell formation and oogenesis. In the present study, ASCs were established from skin, adipose and ovarian tissues of minipigs. Isolated cells exhibited a fibroblast-like morphology with higher proliferation potential and stronger alkaline phosphatase (AP) activity. ASCs from all tissues expressed pluripotent transcriptional factors, such as Oct-3/4, Nanog and Sox-2 and phenotypic markers, including CD29, CD44, CD90 and vimentin. Further, ASCs were successfully dIfferentiated into osteocytes, adipocytes and neuron-like cells. Upon induction in oogenesis specific media, all ASCs were capable of differentiation into OLCs by exhibiting distinct morphological features. Generated OLCs expressed a range of germ cell specific markers, such as Vasa, deleted in Azoospermia-like (DAZL) factor, stella, c-kit, c-Mos, synaptonemal complex protein 3 (SCP-3), growth differentiation factor 9b (GDF- 9b), zona pellucida C (ZPC) and follicle stimulating hormone receptor (FSHR) at different time points of induction. Differentiated OLCs were also positive for the expression of Vasa and DAZL protein markers. Our findings showing that OLCs can be generated from ASCs of different tissue origin may offer pig as a suitable model for designing transgenic application strategies for reproductive tissue therapy. However, further studies are needed to understand the cellular and molecular mechanisms involved in germ cell differentiation from tissue specific stem cells.

In general, zona pellucida (ZP) of the blastocyst has to be removed first, then either isolated the inner cell mass (ICM) or ZP-removed whole blastocyst, which is then cultured on the feeder layer to induce ICM outgrowth for the generation of embryonic stem cells (ESC). However, it is unclear whether ICM isolation before seeding on feeder layer is beneficial or not because the interaction between ICM and trophoblasts may affect cellular growth and/or pluripotency during the culture on the feeder. In the present study, two ZP removal methods (mechanically by splitting with a 28-gauge needle versus chemically by the treatment of acid-Tyrode's solution) and two ICM isolation methods (ZP-free whole blastocyst seeding versus mechanical isolation of ICM) were evaluated for the efficient isolation and culture of putative parthenogenetic bovine ESC. The number of maintained outgrown colonies was counted in each experimental group. As the result, mechanical removal of ZP with a needle and followed by whole ZP-free blastocyst seeding on feeder cells tended to attach more on the feeder layer and resulted in more outgrown colonies with its simple and less time-costing benefits. Currently we are generating ESC lines in HanWoo cattle by using this method for initial outgrowth of the parthenogenetic bovine blastocysts.