Establishment and characterization of a novel human induced pluripotent stem cell line stably expressing the iRFP720 reporter

Stem cell therapy has great potential for replacing beta-cell loss in diabetic patients. However, a key obstacle to cell therapy’s success is to preserve viability and function of the engrafted cells. While several strategies have been developed to improve engrafted beta-cell survival, tools to evaluate the efficacy within the body by imaging are limited. Traditional labeling tools, such as GFP-like fluorescent proteins, have limited penetration depths in vivo due to tissue scattering and absorption. To circumvent this limitation, a near-infrared fluorescent mutant version of the DrBphP bacteriophytochrome, iRFP720, has been developed for in vivo imaging and stem/progenitor cell tracking. Here, we present the generation and characterization of an iRFP720 expressing human induced pluripotent stem cell (iPSC) line, which can be used for real-time imaging in various biological applications. To generate the transgenic cells, the CRISPR/Cas9 technology was applied. A puromycin resistance gene was inserted into the AAVS1 locus, driven by the endogenous PPP1R12C promoter, along with the CAG-iRFP720 reporter cassette, which was flanked by insulator elements. Proper integration of the transgene into the targeted genomic region was assessed by comprehensive genetic analysis, verifying precise genome editing. Stable expression of iRFP720 in the cells was confirmed and imaged by their near-infrared fluorescence. We demonstrated that the reporter iPSCs exhibit normal stem cell characteristics and can be efficiently differentiated towards the pancreatic lineage. As the genetically modified reporter cells show retained pluripotency and multilineage differentiation potential, they hold great potential as a cellular model in a variety of biological and pharmacological applications.

Integration of nano- and biotechnology for beta-cell and islet transplantation in type-1 diabetes treatment

Regenerative medicine using human or porcine β‐cells or islets has an excellent potential to become a clinically relevant method for the treatment of type‐1 diabetes. High‐resolution imaging of the function and faith of transplanted porcine pancreatic islets and human stem cell–derived beta cells in large animals and patients for testing advanced therapy medicinal products (ATMPs) is a currently unmet need for pre‐clinical/clinical trials. The iNanoBIT EU H2020 project is developing novel highly sensitive nanotechnology‐based imaging approaches allowing for monitoring of survival, engraftment, proliferation, function and whole‐body distribution of the cellular transplants in a porcine diabetes model with excellent translational potential to humans. We develop and validate the application of single‐photon emission computed tomography (SPECT) and optoacoustic imaging technologies in a transgenic insulin‐deficient pig model to observe transplanted porcine xeno‐islets and in vitro differentiated human beta cells. We are progressing in generating new transgenic reporter pigs and human‐induced pluripotent cell (iPSC) lines for optoacoustic imaging and testing them in transplantable bioartificial islet devices. Novel multifunctional nanoparticles have been generated and are being tested for nuclear imaging of islets and beta cells using a new, high‐resolution SPECT imaging device. Overall, the combined multidisciplinary expertise of the project partners allows progress towards creating much needed technological toolboxes for the xenotransplantation and ATMP field, and thus reinforces the European healthcare supply chain for regenerative medicinal products.

Systematic in vitro and in vivo characterization of Leukemia-inhibiting factor- and Fibroblast growth factor-derived porcine induced pluripotent stem cells

Derivation and stable maintenance of porcine induced pluripotent stem cells (piPSCs) is challenging. We herein systematically analyzed two piPSC lines, derived by lentiviral transduction and cultured under either leukemia inhibitory factor (LIF) or fibroblast growth factor (FGF) conditions, to shed more light on the underlying biological mechanisms of porcine pluripotency. LIF‐derived piPSCs were more successful than their FGF‐derived counterparts in the generation of in vitro chimeras and in teratoma formation. When LIF piPSCs chimeras were transferred into surrogate sows and allowed to develop, only their prescence within the embryonic membranes could be detected. Whole‐transcriptome analysis of the piPSCs and porcine neonatal fibroblasts showed that they clustered together, but apart from the two pluripotent cell populations of early porcine embryos, indicating incomplete reprogramming. Indeed, bioinformatic analysis of the pluripotency‐related gene network of the LIF‐ versus FGF‐derived piPSCs revealed that ZFP42 (REX1) expression was absent in both piPSC‐like cells, whereas it was expressed in the porcine inner cell mass at Day 7/8. A second striking difference was the expression of ATOH1 in piPSC‐like cells, which was absent in the inner cell mass. Moreover, our gene expression analyses plus correlation analyses of known pluripotency genes identified unique relationships between pluripotency genes in the inner cell mass, which are to some extent, in the piPSC‐like cells. This deficiency in downstream gene activation and divergent gene expression may be underlie the inability to derive germ line‐transmitting piPSCs, and provides unique insight into which genes are necessary to achieve fully reprogrammed piPSCs. 84: 229–245, 2017. © 2016 Wiley Periodicals, Inc.

Generation of neuronal progenitor cells and neurons from mouse sleeping beauty transposon-generated induced pluripotent stem cells

Mouse embryonic stem cells (ESCs) and induced pluripotent stem (iPS) cells can be used as models of neuronal differentiation for the investigation of mammalian neurogenesis, pharmacological testing, and development of cell-based therapies. Recently, mouse iPS cell lines have been generated by Sleeping Beauty (SB) transposon-mediated transgenesis (SB-iPS). In this study, we determined for the first time the differentiation potential of mouse SB-iPS cells to form neuronal progenitor cells (NPCs) and neurons. Undifferentiated SB-iPS and ES cells were aggregated into embryoid bodies (EBs) and cultured in neuronal differentiation medium supplemented with 5 μM all-trans retinoic acid. Thereafter, EBs were dissociated and plated to observe further neuronal differentiation. Samples were fixed on days 10 and 14 for immunocytochemistry staining using the NPC markers Pax6 and Nestin and the neuron marker βIII-tubulin/Tuj1. Nestin-labeled cells were analyzed further by flow cytometry. Our results demonstrated that SB-iPS cells can generate NPCs and differentiate further into neurons in culture, although SB-iPS cells produced less nestin-positive cells than ESCs (6.12 ± 1.61 vs. 74.36 ± 1.65, respectively). In conclusion, the efficiency of generating SB-iPS cells-derived NPCs needs to be improved. However, given the considerable potential of SB-iPS cells for drug testing and as therapeutic models in neurological disorders, continuing investigation of their neuronal differentiation ability is required.

Generation of mouse induced pluripotent stem cells from different genetic backgrounds using Sleeping beauty transposon mediated gene transfer

Induced pluripotent stem (iPS) cell technology involves reprogramming somatic cells to a pluripotent state. The original technology used to produce these cells requires viral gene transduction and results in the permanent integration of exogenous genes into the genome. This can lead to the development of abnormalities in the derived iPS cells. Here, we report that non-viral transfection of a Sleeping Beauty (SB) transposon containing the coding sequences Oct3/4 (Pouf1), Sox-2, Klf-4 and c-Myc (OSKM) linked with 2A peptides, can reprogram mouse fibroblasts. We have established reprogrammed mouse cell lines from three different genetic backgrounds: (1) ICR-outbred, (2) C57BL/6-inbred and (3) F1-hybrid (C57BL/6 x DBA/2J), with parallel robust expression of all exogenous (Oct3/4, Sox-2, Klf-4, and c-Myc) and endogenous (e.g. Oct3/4 and Nanog) pluripotency genes. The iPS cell lines exhibited characteristics typical for undifferentiated embryonic stem (ES) cell lines: ES cell-like morphology, alkaline phosphatase (ALP) positivity and gene expression pattern (shown by reverse transcription PCR, and immunofluorescence of ES cell markers-e.g. Oct3/4, SSEA1, Nanog). Furthermore, cells were able to form embryoid bodies (EBs), to beat rhythmically, and express cardiac (assayed by immunofluorescence, e.g. cardiac Troponin T, desmin) and neuronal (assayed by immunofluorescence e.g. nestin, Tuj1) markers. The in vitro differentiation potential was found to be the highest in the ICR-derived iPS lines (ICR-iPS). Interestingly, the ICR-iPS lines had even higher differentiation potential than the ICR-ES cell lines: the rate of EBs forming rhythmically beating cardiomyocytes was 4% in ICR-ES and 79% in ICR-iPS cells, respectively. In vivo, the ICR and F1 hybrid iPS cells formed chimeras and one of the iPS cells from the F1 hybrid background transmitted to the germline. Our results suggest that iPS technology may be useful for generating pluripotent stem cells from genetic backgrounds of which good quality ES cell generation is difficult. These studies provide insights into viral-free iPS technology and may contribute towards defining future cell-based therapies, drug-screening methods and production of transgenic animals using genetically modified iPS cells.

292 GENERATION OF MOUSE INDUCED PLURIPOTENT STEM CELLS FROM VARIOUS GENETIC BACKGROUND BY SLEEPING BEAUTY TRANSPOSON-MEDIATED GENE TRANSFER

Induced pluripotent stem (iPS) cell technology allows the reprogramming of somatic cells to a pluripotent state; however, it requires viral gene transduction and permanent existence of the exogenous genes in the genome, which is a potential risk for abnormalities in the derived iPS cells. Recently, there was report that iPS cells have been made with piggyBack transposon. Here, we first reported that nonviral transfection of a Sleeping Beauty transposon, which comprises c-Myc, Klf-4, Oct3/4 (Pou5f1), and Sox-2, can reprogram mouse fibroblasts from 3 different genetic backgrounds: ICR (outbred), C57BL/6 (inbred), and F1 hybrid (C57BL/6 × DBA/2J), with parallel robust expression of all exogenous (c-Myc, Klf-4, Oct3/4, and Sox-2) and endogenous (e.g. Nanog) pluripotency genes. The iPS cells were cultured under standard conditions with promotion of differentiate by withdrawal of leukemia inhibitory factor. We chose 6 cloned of each line that exhibited characteristics typical for undifferentiated embryonic stem (ES) cell: ES-cell-like morphology, alkaline phosphatase positivity, and gene expression pattern [quantitative real-time PCR and immunofluorescence of ES cell markers (e.g. Oct-4, SSEA1, Nanog]. Furthermore, cells were able to form embryoid bodies and beat rhythmically and expressed cardiac markers assayed by immunofluorescence (e.g. cardiac Troponin T, desmin). In vivo testing of iPS cell lines for their developmental potential (diploid and tetraploid embryo complementation assay) is currently underway. The iPS cell lines generated from the ICR strain appeared the earliest in time (ICR-d11, F1 day-2 and Bl6-d12), with higher efficiency than colonies from the other 2 backgrounds. The differentiation potential of the iPS lines derived from the 3 genetic backgrounds was similar. Interestingly, the ICR-iPS lines had higher differentiation potential than did the ICR-ES cell lines: the rate of embryoid bodies forming rhythmically beating cardiomyocytes was 4% in ICR-ES and 79% in ICR-iPS cells, respectively. Our results suggest that the iPS technology provide a new tool to generate pluripotent stem cells from genetic backgrounds where good-quality ES cell generation is difficult. These studies provide new insights into virus-free iPS technology and contribute to defining future cell-based therapies, drug screening methods, and production of transgenic animals with genetically modified iPS cells. This study was financed by EU FP6 (CLONET, MRTN-CT-2006-035468), EU FP7 (PartnErS, PIAP-GA-2008-218205; InduHeart, PEOPLE-IRG-2008-234390; InduVir, PEOPLE-IRG-2009-245808; InduStem, PIAP-GA-2008-230675; PluriSys, HEALTH-2007-B-223485); NKTH-OTKA-EU FP7-HUMAN-2009-MB08-C 80205, and NKTH/KPI (Jedlik NKFP_07_1-ES2HEART-HU OM-00202-2007).

398 DIFFERENTIATION OF MOUSE EMBRYONIC STEM CELLS INTO CARDIOMYOCYTES BY USING SLOW TURNING LATERAL VESSEL (STLV/BIOREACTOR)

Cardiomyocytes derived from embryonic stem (ES) cells are anticipated to be valuable for cardiovascular drug testing and disease therapies. The overall efficiency and quantity of cardiomyocytes obtained by differentiation of ES cells is still low. To enable a large-scale culture of ES-derived cells, we have tested a scalable bioprocess that allows direct embryoid body (EB) formation in a fully controlled, bioreactor/STLV (slow turning lateral vessel, Synthecon, Inc., Houston, TX, USA) following inoculation with a single cell suspension of mouse ES cells. Technical parameters for optimal cell expansion and efficient ES cell differentiation were compared, such as ES cell seeding density (3 × 105 and 5 × 105 cells mL-1) into the bioreactor and day of transfer and plating of EB on gelatinated petri dishes (Day 2, Day 3, Day 4, and Day 5). The quantity and quality of EB production including the yield and size of EB, as well as viability and apoptosis of cells, were analyzed. Furthermore, after cultivation, well-developed contracting EB with functional cardiac muscle were obtained in which the percentage of EB beating/well and several specific cardiac genes [cardiac Troponin T (cTnT) and α-actinin] expression were also determined. Data are expressed as mean ± SEM of at least 3 independent experiments. Statistical analyses included one-way ANOVA and Student’s t-test Statistical significance was set at P < 0.05. The results showed that 5 × 105 ES cells mL-1 seeded into the STLV significantly improved the homogeneity of size of EB formed compared with 3 × 105 ES cells mL-1. The EB derived from Days 2 or 3 culturing in STLV had less necrotic cells than Days 4 and 5 groups. Furthermore, plating these EB on Days 2 and 3 resulted in significantly more EB beating/well than that of Days 4 and 5 groups. For cardiac differentiation, the group with 5 × 105 ES cells mL-1 seeded into STLV and transferred and plated on Day 3 expressed more cardiac markers than other groups. In conclusion, the optimized rotary suspension culture method can produce a highly uniform population of efficiently differentiating EB in large quantities in a manner that can be easily implemented by basic research laboratories. This method provides a technological platform for the controlled large-scale generation of ES cell-derived cells for clinical and industrial applications. This work was financed by The Thailand Commission on Higher Education (CHE-PhD-SW-2005-100), EUFP6 CLONET (MRTN-CT-2006-035468), NKFP_07_1-ES2HEART-HU (OM-00202-2007), and EUFP7 (PartnErS, PIAP-GA-2008-218205).

Quality analysis of buffalo blastocysts derived from oocytes vitrified before or after enucleation and reconstructed with somatic cell nuclei

We investigated the potential of vitrified-warmed buffalo oocytes to develop to blastocysts after parthenogenetic activation (PA) and somatic cell nuclear transfer (SCNT). In vitro-matured oocytes before and after enucleation (M-II oocytes and enucleated oocytes, respectively) were put in 7.5% DMSO and 7.5% ethylene glycol (EG) for 4, 7 and 10 min, and then vitrified (Cryotop device) after 1-min equilibration in 15% DMSO, 15% EG and 0.5M sucrose. Following 4-, 7- and 10-min exposure, proportions of the post-warm oocytes with a normal vitelline membrane were similar (66-71% in M-II oocytes and 69-71% in enucleated oocytes). However, 18-20% of the normal M-II oocytes had no detectable first polar body in their perivitelline space (no potential for subsequent enucleation). When the post-warm M-II oocytes were treated for PA by 7% ethanol, 10 microg/mL cycloheximide and 1.25 microg/mL cytochalasin-D, parthenogenetic development into Day-7 blastocysts occurred in 10-13% of cultured oocytes, lower (P<0.05) than fresh (control) oocytes (24%). In the absence of the cooling and warming, blastocyst rates in the 4-min exposure group (22%), but not in the 7-min and 10-min exposure groups (14-15%), were similar to that in the fresh group (23%). The total cell number (group average 117-132 cells) and the ICM ratio (22-24%) of the PA blastocysts derived from vitrified M-II oocytes were comparable with fresh oocytes (127 cells and 25%). After SCNT (with fibroblast cells and vitrified-warmed oocytes), blastocyst rates were similar for the three exposure periods for M-II oocytes (8-10%) and enucleated oocytes (7-9%), but were lower (P<0.05) than in the fresh group (15%). The total cell number of the SCNT blastocysts derived from vitrified M-II and enucleated oocytes (80-90 and 82-101 cells) was smaller (P<0.05) than from fresh oocytes (135 cells); the ICM ratio of blastocysts derived from the M-II and enucleated oocytes after vitrification in 7- or 10-min exposure groups (20-22%) was not different (P>0.05) from fresh control oocytes (24%) or those in 4-min exposure group (M-II 23%, enucleated 24%). Thus, SCNT of swamp buffalo oocytes following vitrification before or after enucleation resulted in blastocysts with a slightly decreased cell number.

Epigenetic characteristics of cloned and in vitro-fertilized swamp buffalo (Bubalus bubalis) embryos1

Swamp buffalos are becoming endangered due to reproductive inefficiencies. This is of concern because many countries depend heavily on their products. Somatic cell nuclear transfer (SCNT) is a potential strategy for preserving endangered species. To date, SCNT in swamp buffalo has succeeded in the creation of blastocyst embryos. However, development to term of SCNT swamp buffalos is extremely limited, and only 1 live birth has been reported. An abnormal epigenetic mechanism is suspected to be the cause of developmental failure, as is also seen in other species. The DNA methylation and histone acetylation are key players in epigenetic modification and display marked variability during embryonic preimplantation development. Knowledge of epigenetic modifications will aid in solving the developmental problems of SCNT embryos and improving reproductive technology in the swamp buffalo. The objective of this study was to determine the relationship between preimplantation embryonic development and 2 epigenetic patterns, global DNA methylation and histone acetylation, in SCNT and in vitro-fertilized (IVF) swamp buffalo embryos. In addition, we examined the correlations between those 2 mechanisms in the SCNT and IVF swamp buffalo embryos throughout the developmental stages using double immunostaining and quantification of the emission intensities using confocal microscopy. We discovered an aberrant methylation pattern in early preimplantation-stage swamp buffalo SCNT embryos. In addition, greater variability in the DNA methylation levels among nuclei within SCNT embryos was discovered. Hyperacetylation was also observed in SCNT embryos compared with IVF embryos at the 4- and 8-cell stages (P < 0.05). Dynamic changes and interplay between these 2 epigenetic mechanisms could be crucial for embryonic development during the early preimplantation period. The aberrancies uncovered here may contribute to the low efficiency of SCNT.

Anomalous mRNA levels of chromatin remodeling genes in swamp buffalo (Bubalus bubalis) cloned embryos

The swamp buffalo (Bubalus bubalis) is a multi-purpose animal in agriculture that is challenged by extinction due to low reproductive efficiency. Nuclear transfer (NT) has been used to preserve special breeds of buffalo, as well as to increase the number of animals. However, cloned buffalo embryos have impaired development, as in other species. To understand the chromatin remodeling activities in cloned embryos and to improve NT technology, we examined the expression profiles of five genes involved in DNA and histone modifications, DNMT1, DNMT3A, DNMT3B, HAT1 and HDAC1, in single swamp buffalo metaphase II oocytes, NT and in vitro fertilized (IVF) embryos from the two-cell to the blastocyst stage, by quantitative real time RT-PCR. We observed similar expression dynamics for all genes studied in the NT and IVF embryos: relatively constant levels of expression for all genes were found from the MII oocyte up to the eight-cell stage; the levels of mRNA for HAT1 and DNMT3B continued to be stably expressed up to the blastocyst stage; while dramatic increases were seen for DNMT3A and HDAC1. Alternatively, the levels of DNMT1 started to decrease at the eight-cell stage. Despite the similarity in the dynamics of gene expression, dramatic differences in the relative levels of these genes between NT and IVF embryos were observed. The expression levels of all DNA modifying genes were higher in the NT embryos than in the IVF embryos at the eight-cell and blastocyst stages. The genes HDAC1 and HAT1 were also expressed significantly higher at the blastocyst stage in the NT embryos. Our results suggested differences in chromatin remodeling between NT and IVF embryos and that lower levels of DNA passive demethylation and higher levels of DNA de novo methylation occurred in the NT embryos. These observations are novel in the species of buffalo, and may be associated with developmental failure of cloned buffalo embryos due to the transcriptional repression effect of most genes studied here.

104EFFECT OF HATCHING STATUS ON VITRIFICATION OF CLONED BOVINE BLASTOCYSTS

Bovine blastocysts produced by nuclear transplantation have mechanical slits in their zonae pellucidae, and therefore initiate hatching earlier than the non-manipulated embryos. The present study was undertaken to examine whether the hatching stage of cloned blastocysts is among the factors influencing their survival after vitrification and warming. Cloned bovine blastocysts were produced by using adult ear fibroblast cells as reported previously (Parnpai et al., 2002, Theriogenology 57, 443), except that fused couplets were co-cultured with bovine oviductal epithelial cells in mSOFaa medium supplemented with 0.1% linoleic acid-albumin (LAA)+0.2% BSA (Hochi et al., 1999, Theriogenology 52, 497–504). Hatching blastocysts harvested on Day 7 were classified into one of three groups according to the ratio of extruding embryonic diameter from zona (D2) to embryonic diameter inside the zona (D1); category-A: D2/D1=0.01–0.70; category-B: D2/D1=0.71–1.00; category-C: D2/D1=1.01–1.70. The blastocysts were first exposed to 10% DMSO+10% ethylene glycol in TCM199+20% FCS for 2min, and then equilibrated in 20% DMSO+20% ethylene glycol+0.5M sucrose with or without 10% Ficoll in TCM199+20% FCS for 30s. One to three blastocysts were placed on a Cryotop sheet (Kitazato Supply Co., Tokyo, Japan) and vitrified in liquid nitrogen. The samples were warmed in 0.5M sucrose solution for 2min and transferred into TCM199+20% FCS in five steps (5min per step). The post-warm survival of the blastocysts was assessed by in vitro culture for 24h. When Ficoll-free vitrification solution was used, post-warm survival rate of the category-A blastocysts (77%, 23/30) was not significantly different (ANOVA test) from those of category-B and category-C blastocysts (74%, 20/27; and 80%, 24/30; respectively). Inclusion of 10% Ficoll in the vitrification solution did not improve (ANOVA test) the post-warm survival rates of cloned blastocysts (category-A: 65%, 22/34; category-B: 54%, 15/28; category-C: 59%, 19/32). Groups of fresh nonsurgical embryos, vitrified with or without Ficoll, yielded 66.7% (4/6), 66.7% (2/3) and 40.0% (2/5), respectively, of recipients pregnant at 48 days of gestation. In conclusion, cloned bovine blastocysts, regardless of their hatching stages, were relatively resistant to cryopreservation by vitrification. (Supported by Thailand Research Fund and R&amp;D Fund of Suranaree University of Technology.)

116DEVELOPMENT INTO BLASTOCYSTS OF SWAMP BUFFALO OOCYTES AFTER VITRIFICATION AND NUCLEAR TRANSFER

Oocyte cryopreservation in the domestic species is still at the experimental stage, but recent studies indicated that vitrification characterized by ultra-rapid cooling rate is promising for cryopreservation of bovine oocytes. In the present study, denuded buffalo oocytes were vitrified by minimum volume cooling procedure (Kuwayama and Kato, 2000, J Assist Reprod Genet 17, 477) after IVM or after IVM and enucleation, and developmental potential into blastocysts of the post-warm oocytes after somatic cell nuclear transplantation was examined. Cumulus-oocyte complexes were matured, denuded, and enucleated as described previously (Parnpai et al., 1999, Buffalo J 3, 371–384). The presumptive metaphase-II (M-II) oocytes before and after enucleation were first equilibrated in 7.5% DMSO+7.5% ethylene glycol+20% FCS in TCM199 for 10 min, and then exposed to 15% DMSO+15% ethylene glycol+0.5M sucrose+20% FCS in TCM199 for 1min. Five oocytes were placed on a Cryotop sheet (Kitazato Supply Co., Tokyo, Japan) and vitrified in liquid nitrogen. The samples were warmed in 0.5M sucrose solution for 5min, directly transferred into TCM199+20% FCS, and kept at room temperature for 1h before being used for a cloning experiment. The post-warm oocytes were fused with ear skin fibroblasts by two DC pulses (26V, 17μs) and activated with 7% ethanol for 5min and then 10μg/mL cycloheximide and 1.25μg/mL cytochalasin-D for 5h. The reconstructed embryos were cultured in mSOFaa+0.2% BSA+0.1% linoleic acid albumin for 2 days, and then co-cultured with bovine oviductal epithelial cells for an additional 5 days. Post-warm morphological survival of M-II oocytes (80%, 187/235) was similar to that of enucleated oocytes (75%, 158/212). Vitrified M-II oocytes were successfully enucleated (96%, 136/142) as were fresh control oocytes (88%, 143/162). Fusion rates of M-II oocytes vitrified before and after enucleation (81%, 94/116 and 78%, 106/136, respectively) were also similar to those of fresh oocytes (81%, 100/123). Percentages of reconstructed embryos developing into hatching blastocysts on Day 7 were 5% (5/91), 6% (6/103), and 8% (8/99) in the groups of oocytes vitrified before and after enucleation, and of fresh control oocytes, respectively (ANOVA tests were not significant different). These results indicate that swamp buffalo oocytes cryopreserved by ultra-rapid vitrification procedure can be used successfully for subsequent somatic cell nuclear transplantation. (Supported by Thailand Research Fund and R&amp;D Fund of Suranaree University of Technology)

55IN VITRO DEVELOPMENT OF ENUCLEATED DOMESTIC CAT OOCYTES RECONSTRUCTED WITH SKIN FIBROBLASTS OF DOMESTIC AND LEOPARD CATS

The domestic cat is a valuable model for studies in assisted reproductive technology in felid species. Therefore, in this experiment we evaluated the in vitro developmental potential of enucleated domestic cat oocytes reconstructed with somatic cells from domestic and leopard cats. Skin fibroblasts were isolated from female domestic and leopard cats. The oocytes were collected by aspiration of follicles from ovaries that were superovulated with 200IU PMSG. In vitro-matured oocytes were enucleated and individual donor cells (diameter 14–16μm) were inserted into the perivitelline space of the enucleated oocyte. Fusion was performed at 26–27h post-maturation by placing a cell-oocyte couplet between both tips of the needle electrode and electrostimulating with a 2-DC pulse (30V, 30μs) in fusion medium containing 0.3M Mannitol+0.1mM MgCl2. Activation was performed 1 to 2h post-fusion by incubation in 7% ethanol at room temperature for 5min followed by cultured in 10μgmL−1 cycloheximide and 1.25μgmL−1 cytochalasin D at 38°C in 5% O2, 5% CO2, 90% N2 conditions. After activation, the reconstructed embryos were cultured in 100-μL droplets of Tyrode’s medium (Gomez et al., 2003 Theriogenology 60, 239–251.) supplemented with 0.3% BSA at 38°C in a 5% O2, 5% CO2, 90% N2 environment for 2d. Then, 8-cell embryos were cultured in 100-μL droplets of Tyrode’s medium supplemented with 10% FCS at 38°C in a 5% O2, 5% CO2, 90% N2environment for 5d. The cleavage rates of oocytes reconstructed with either donor cell types were not different. The percentages of blastocyst formation from parthenogenotes and nuclear transfer embryos derived from domestic cat fibroblasts (8/56, 14.3% and 7/51, 13.7%, respectively) were significantly higher than that for nuclear transfer embryos constructed with leopard cat fibroblasts (3/45, 6.7%). These results indicate that enucleated domestic cat oocytes reconstructed with skin fibroblasts of leopard cats can develop to the blastocyst stage. This experiment was supported by Suranaree University of Technology. Table 1 In vitro development of domestic cat oocytes reconstructed with domestic and leopard skin fibroblasts and parthenogenetic activation