Production of transgenic canine embryos using interspecies somatic cell nuclear transfer

Zygote ◽  
2011 ◽  
Vol 20 (1) ◽  
pp. 67-72 ◽  
Author(s):  
So Gun Hong ◽  
Hyun Ju Oh ◽  
Jung Eun Park ◽  
Min Jung Kim ◽  
Geon A. Kim ◽  
...  

SummarySomatic cell nuclear transfer (SCNT) has emerged as an important tool for producing transgenic animals and deriving transgenic embryonic stem cells. The process of SCNT involves fusion of in vitro matured oocytes with somatic cells to make embryos that are transgenic when the nuclear donor somatic cells carry ‘foreign’ DNA and are clones when all the donor cells are genetically identical. However, in canines, it is difficult to obtain enough mature oocytes for successful SCNT due to the very low efficiency of in vitro oocyte maturation in this species that hinders canine transgenic cloning. One solution is to use oocytes from a different species or even a different genus, such as bovine oocytes, that can be matured easily in vitro. Accordingly, the aim of this study was: (1) to establish a canine fetal fibroblast line transfected with the green fluorescent protein (GFP) gene; and (2) to investigate in vitro embryonic development of canine cloned embryos derived from transgenic and non-transgenic cell lines using bovine in vitro matured oocytes. Canine fetal fibroblasts were transfected with constructs containing the GFP and puromycin resistance genes using FuGENE 6®. Viability levels of these cells were determined by the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay. Interspecies SCNT (iSCNT) embryos from normal or transfected cells were produced and cultured in vitro. The MTT measurement of GFP-transfected fetal fibroblasts (mean OD = 0.25) was not significantly different from non-transfected fetal fibroblasts (mean OD = 0.35). There was no difference between transgenic iSCNT versus non-transgenic iSCNT embryos in terms of fusion rates (73.1% and 75.7%, respectively), cleavage rates (69.7% vs. 73.8%) and development to the 8–16-cell stage (40.1% vs. 42.7%). Embryos derived from the transfected cells completely expressed GFP at the 2-cell, 4-cell, and 8–16-cell stages without mosaicism. In summary, our results demonstrated that, following successful isolation of canine transgenic cells, iSCNT embryos developed to early pre-implantation stages in vitro, showing stable GFP expression. These canine–bovine iSCNT embryos can be used for further in vitro analysis of canine transgenic cells and will contribute to the production of various transgenic dogs for use as specific human disease models.

Zygote ◽  
2009 ◽  
Vol 17 (3) ◽  
pp. 195-202 ◽  
Author(s):  
Atsushi Sugawara ◽  
Satoshi Sugimura ◽  
Yumi Hoshino ◽  
Eimei Sato

SummaryCloning that uses somatic cell nuclear transfer (SCNT) technology with gene targeting could be a potential alternative approach to obtain valuable rat models. In the present study, we determined the developmental competence of rat SCNT embryos constructed using murine and porcine oocytes at metaphase II (MII). Further, we assessed the effects of certain factors, such as: (i) the donor cell type (fetal fibroblasts or cumulus cells); and (ii) premature chromosome condensation (PCC) with normal spindle formation, on the developmental competence of rat interspecies SCNT (iSCNT) embryos. iSCNT embryos that had been constructed using porcine oocytes developed to the blastocyst stage, while those embryos made using murine MII oocytes did not. Rat iSCNT embryos constructed with green fluorescent protein (GFP)-expressing fetal fibroblasts injected into porcine oocytes showed considerable PCC with a normal bipolar spindle formation. The total cell number of iSCNT blastocyst derived from GFP-expressing fetal fibroblasts was higher than the number derived from cumulus cells. In addition, these embryos expressed GFP at the blastocyst stage. This paper is the first report to show that rat SCNT embryos constructed using porcine MII oocytes have the potential to develop to the blastocyst stage in vitro. Thus the iSCNT technique, when performed using porcine MII oocytes, could provide a new bioassay system for the evaluatation of the developmental competence of rat somatic cells.


2006 ◽  
Vol 18 (2) ◽  
pp. 123
Author(s):  
G. Coppola ◽  
B.-G. Jeon ◽  
B. Alexander ◽  
E. St. John ◽  
D. H. Betts ◽  
...  

The early reprogramming events following somatic cell nuclear transfer (SCNT) determine the fate of the cloned embryo and its development to a healthy viable offspring. In the present study, we undertook a detailed immunocytochemical study of the patterns of both microtubules and chromatin during the first cell cycle of sheep nuclear transfer embryos after fusion and artificial activation using either 6-dimethylaminopurine (6-DMAP) or cycloheximede (CHX). Sheep oocytes were collected from abattoir ovaries and matured in vitro for 18-20 h and enucleated; fetal fibroblasts were transplanted using standard SCNT techniques. Reconstructed cell-cytoplast couplets were fused and activated with ionomycin, followed by culture in two separate groups containing 6-DMAP (2 mM) or CHX (10 �g/mL) for 3 h. Following activation, embryos were cultured in in vitro culture (IVC) medium for blastocyst development. Embryos (n = 15, 3 replicates) were randomly removed from culture at various time points and stained using standard immunocytochemical methods to observe microtubule and nuclear configurations. Images were captured using laser scanning confocal microscopy. Results reveled that at 1 h post-fusion, 63.3% of reconstructed embryos underwent nuclear envelope breakdown (NEBD) and premature chromosome condensation (PCC) was apparent as chromosomes were situated on a non-polar spindle. The remaining embryos showed abnormal spindle and DNA configurations including chromosome outliers, congression failure, and non-NEBD. At 1 h post-activation (hpa), the embryos treated with 6-DMAP had already formed a clearly visible pronucleus (diameter 6-8 �m), whereas in the CHX-treated group, none of the embryos were at pronuclear stage; instead most of the latter embryos showed two masses of chromatin. At 1 hpa, 6-DMAP- and CHX-treated embryos showed one swelled pronucleus with a mean diameter of 8.4 � 1.3 �m and 25.8 � 0.8 �m, respectively (P < 0.05). At 16 hpa, embryos from both treatment groups still showed one swelled pronucleus. In the 6-DMAP-treated embryos, most of the embryos showed a metaphase spindle with aligned chromosomes of the first mitotic division as early as 18-10 hpa, whereas in the CHX-treated group embryos were still at the pronuclear stage. Typical 2-cell division was seen in most of the 6-DMAP-treated embryos between 24 and 30 hpa, but it was slightly delayed in CHX-treated embryos (32-35 hpa). Blastocyst development rates in the 6-DMAP- and CHX-treated groups were 21.4 � 5.6% and 14.0 � 6.3%, respectively (P < 0.05). In summary, artificial activating agents 6-DMAP and CHX exhibited different effects on chromatin remodeling, cell cycle progression, and the degree of pronuclear swelling which may explain the poor developmental rates and abnormal chromosome complements observed for cloned embryos. This work was funded by NSERC, OMAF, and International Council for Canadian Studies.


2007 ◽  
Vol 19 (1) ◽  
pp. 147
Author(s):  
E. Lee ◽  
K. Song ◽  
Y. Jeong ◽  
S. Hyun

Generally, blastocyst (BL) formation and embryo cell number are used as main parameters to evaluate the viability and quality of in vitro-produced somatic cell nuclear transfer (SCNT) embryos. We investigated whether in vitro development of SCNT pig embryos correlates with in vivo viability after transfer to surrogates. For SCNT, cumulus–oocyte complexes (COCs) were matured in TCM-199 supplemented with follicular fluid, hormones, EGF, cysteine, and insulin for the first 22 h and in a hormone-free medium for 18 h. Three sources of pig skin cells were used as nuclear donor: (1) skin fibroblasts of a cloned piglet that were produced by SCNT of fetal fibroblasts from a Landrace × Yorkshire × Duroc F1 hybrid (LYD), (2) skin fibroblasts of a miniature pig having the human decay accelerating factor gene (hDAF-MP), and (3) skin fibroblasts of a miniature pig with a different strain (MP). MII oocytes were enucleated, subjected to nuclear transfer from a donor cell, electrically fused, and activated 1 h after fusion. SCNT embryos were cultured in a modified NCSU-23 (Park Y et al. 2005 Zygote 13, 269–275) for 6 days or surgically transferred (110–150 fused embryos) into the oviduct of a surrogate that showed standing estrus on the same day as SCNT. Embryos were examined for cleavage and BL formation on Days 2 and 6, respectively (Day 0 = the day of SCNT). BLs were examined for their cell number after staining with Hoechst 33342. Pregnancy was diagnosed by ultrasound 30 and 60 days after embryo transfer. Embryo cleavage was not affected by donor cells (82, 81, and 72% for LYD, hDAF-MP, and MP, respectively), but BL formation was higher (P &lt; 0.05) in hDAF-MP (16%) than in LYD (9%) and MP (6%). MP showed higher (P &lt; 0.05) BL cell number (46 cells/BL) than hDAF-MP (34 cells) but did not show a difference from LYD (37 cells). LYD and MP showed higher pregnancy rates (Table 1) on Days 30 and 60, even though they showed lower BL formation in vitro. Due to a relatively small number of embryo transfers through a limited period, we could not exclude any possible effects by seasonal or operational differences. These results indicated that pregnancy did not correlate with in vitro BL formation of SCNT pig embryos but rather were affected by the source of donor cells. Table 1.In vivo development of somatic cell nuclear transfer pig embryos derived from different sources of donor cells This work was supported by the Research Project on the Production of Bio-organs (No. 200506020601), Ministry of Agriculture and Forestry, Republic of Korea.


2010 ◽  
Vol 22 (1) ◽  
pp. 191
Author(s):  
D. K. Kwon ◽  
J. T. Kang ◽  
S. J. Park ◽  
M. N. L. Gomez ◽  
S. J. Kim ◽  
...  

Interspecies somatic cell nuclear transfer (iSCNT) has alternatively chosen in primate SCNT because of the difficulty in collecting enough oocytes for research. The purpose of this experiment is to produce iSCNT-derived blastocysts using enucleated cow (Bos taurus) metaphase II oocytes and adult rhesus monkey (Macaca mulatta) fibroblasts. Ear skin tissueofrhesus monkey (male, 6 years old) was collected by biopsy and fibroblasts were isolated. Immature COCs from cow ovaries were collected and matured in vitro in TCM-199. Squish enucleation was done in the presence of bisbenzimide and cytochalasin B. After enucleation, a single rhesus monkey somatic cell was injected into the perivitelline space of an enucleated oocyte through the slit in the zona pellucida made during enucleation. Subsequently, the rhesus monkey somatic cell and cow oocyte membranes were electrically fused. The nonactivated interspecies cloned couplets were cultured for 2 h to allow reprogramming to occur. Then, couplets were activated using a 2-step protocol consisting of treatment with 5 μM ionomycin for 4 to 5 min and subsequently with 2mM 6-DMAP for 4 h. Activated iSCNT embryos were cultured for 10 days inmodified SOF with various conditions (at 37 to39°C, 5 to 5.5% CO2 and 5 to 20% O2) to examine the effects ofIVC conditions. As a results, most embryos were arrested at the 8- to 16-cell stage and only 3 blastocysts were derived from rhesus monkey iSCNT. The blastocyst developmental rate was 0.26% generated from the total IVC activated interspecies embryos (n = 1153). Among the 3 blastocysts, 2 of them were used for counting nuclear number using bisbenzimide staining. The nuclear number of the 2 iSCNT-derived blastocysts was 51 and 24, respectively. The other iSCNT-derived blastocyst was used for analyzing mitochondrial (mt)DNAto confirm that it contained both cow and rhesus monkey mtDNA. As a result, mtDNA from both rhesus monkey and cow were detected inPCR analysis. The band intensity was more dominant for cow mtDNA than for rhesus monkey mtDNA. Although the blastocyst developmental rate is extremely low, it is confirmed that two phylogenetically distant species including primate could develop in vitro until the blastocyst stage by iSCNT. The in vitro developmental system of this rhesus monkey iSCNT-derived blastocysts provides a platform for further improvement of developmental rate and quality of rhesus monkey iSCNT-derived blastocysts. It also provides an opportunity to establish rhesus monkey iSCNT-derived embryonic stem cell lines for study of rhesus monkey nucleus and cow mitochondria interaction mechanisms during early developmental stages. This study was financially supported by the Korean MEST, through the BK21 program for Veterinary Science, and SNU foundation (Benefactor; RNL Bio).


2016 ◽  
Vol 62 (2) ◽  
pp. 177-185 ◽  
Author(s):  
Hyunju YOO ◽  
Eunhye KIM ◽  
Seon-Ung HWANG ◽  
Junchul David YOON ◽  
Yubyeol JEON ◽  
...  

2017 ◽  
Author(s):  
◽  
Bethany Rae Mordhorst

Gene edited pigs serve as excellent models for biomedicine and agriculture. Currently, the most efficient way to make a reliably-edited transgenic animal is through somatic cell nuclear transfer (SCNT) also known as cloning. This process involves using cells from a donor (which may have been gene edited) that are typically grown in culture and using their nuclear content to reconstruct a new zygote. To do this, the cell may be placed in the perivitelline space of an enucleated oocyte and activated artificially by a calcium-containing media and electrical pulse waves. While it is remarkable that this process works, it is highly inefficient. In pigs the success of transferred embryos becoming live born piglets is only 1-3%. The creation of more cloned pigs enables further study for the benefit of both A) biomedicine in the development of prognosis and treatments and B) agriculture, whether it be for disease resistance, feed efficiency, gas emissions, etc. Two decades of research has not drastically improved the cloning efficiency of most mammals. One of the main impediments to successful cloning is thought to be due to inefficient nuclear reprogramming and remodeling of the donor cell nucleus. In the following chapters we detail our efforts to improve nuclear reprogramming of porcine fetal fibroblasts by altering the metabolism to be more blastomere-like in nature. We used two methods to alter metabolism 1) pharmaceutical agents and 2) hypoxia. After treating donor cells both methods were used in nuclear transfer. Pharmaceutical agents did not improve in vitro development of gestational survival of clones. Hypoxia did improve in vitro development and we are currently awaiting results of gestation.


Zygote ◽  
2011 ◽  
Vol 19 (3) ◽  
pp. 199-204 ◽  
Author(s):  
Dae Kee Kwon ◽  
Jung Taek Kang ◽  
Sol Ji Park ◽  
Ma Ninia Limas Gomez ◽  
Su Jin Kim ◽  
...  

SummaryIn non-human primates, it is difficult to collect sufficient numbers of oocytes for producing identical embryos by somatic cell nuclear transfer (SCNT). Because of this factor, inter-species SCNT (iSCNT) using heterospecific oocytes is an attractive alternative approach. The objective of this study was to produce iSCNT-derived blastocysts using enucleated cow (Bos taurus) metaphase II oocytes and adult rhesus monkey (Macaca mulatta) fibroblasts. Ear skin tissue from a 6-year-old male rhesus monkey was collected by biopsy and fibroblasts were isolated. Immature cumulus–oocyte complexes from cow ovaries were collected and matured in vitro in Medium 199. The enucleated oocytes were reconstructed with rhesus monkey fibroblasts and iSCNT embryos were cultured in modified synthetic oviduct fluid in an atmosphere of 5–5.5% CO2 under various conditions (37–39 °C and 5–20% O2) to examine the effects of in vitro culture conditions. Most embryos were arrested at the 8- or 16-cell stage and only three blastocysts were derived in this way using iSCNT from a total of 1153 cultured activated embryos (0.26% production rate). Two of the three blastocysts were used for counting nuclear numbers using bisbenzimide staining, which were 51 and 24. The other iSCNT-derived blastocyst was used to analyse mitochondrial DNA (mtDNA) by PCR, and both rhesus monkey and cow mtDNA were detected. Although the development rate was extremely low, this study established that iSCNT using two phylogenetically distant species, including a primate, could produce blastocysts. With improvements in the development rate, it may be possible to produce rhesus monkey iSCNT-derived embryonic stem cell lines for studies on primate nucleus and cow mitochondria interaction mechanisms.


2009 ◽  
Vol 21 (1) ◽  
pp. 198
Author(s):  
T. Xiang ◽  
S. Walker ◽  
K. Gregg ◽  
W. Zhou ◽  
V. Farrar ◽  
...  

Oct-4, a POU domain-containing transcription factor encoded by Pou5f1, is selectively expressed in pre-implantation embryos and pluripotent stem cells, but not in somatic cells. Because of such a unique expression feature, Oct-4 can serve as a useful reprogramming indicator in somatic cell nuclear transfer (SCNT). Compared with data of Oct-4 expression in mouse and bovine cloned embryos, little is known about this gene in equine nuclear transfer. In the present study, we investigated Oct-4 expression in donor cells, oocytes, and SCNT embryos to evaluate reprogramming of equine somatic cells following nuclear transfer. Horse ovaries were obtained from a local slaughterhouse and the oocytes collected from the ovaries were matured in vitro in an M199-based medium (Galli et al. 2003 Nature 424, 635) for 24 h. Donor cells were derived from biopsy tissue samples of adult horses and cultured for 1 to 5 passages. Standard nuclear transfer procedures (Zhou et al. 2008 Mol. Reprod. Dev. 75, 744–758) were performed to produce cloned embryos derived from equine adult somatic cells. Cloned blastocysts were obtained after 7 days of in vitro culture of reconstructed embryos. Total RNA were extracted using Absolutely RNA Miniprep/Nanoprep kits (Stratagen, La Jolla, CA) from oocytes (n = 200), donor cells, and embryos (n = 5). DNase I treatment was included in the procedure to prevent DNA contamination. Semiquantitative RT-PCR was performed with optimized cycling parameters to analyze Oct-4, GDF9, and β-actin in equine donor cells, oocytes, and cloned blastocysts. The RT-PCR products were sequenced to verify identity of the genes tested. The relative expression abundance was calculated by normalizing the band intensity of Oct-4 to that of β-actin in each analysis. No transcript of Oct-4 was detected in equine somatic cells used as donor nuclei, consistent with its expression patterns in other animal species, whereas Oct-4 was abundantly expressed in equine SCNT blastocysts derived from the same donor cell line. Oct-4 transcripts were also detected in equine oocytes and whether any maternally inherited Oct-4 mRNA persisted up to the blastocyst stage was unclear in this study. We selected GDF9 to address this question; GDF9 was abundantly detected in equine oocytes, consistent with its expression pattern in mouse and bovine, but not detected in donor cells and cloned blastocysts, suggesting that the GDF9 mRNA from the oocyte was degraded at least by the blastocyst stage. The results from this study imply occurrence of Oct-4 reprogramming in equine SCNT blastocysts, and future analysis for more developmentally important genes is needed to better understand reprogramming at molecular levels in this species.


2012 ◽  
Vol 24 (1) ◽  
pp. 128
Author(s):  
G. Kim ◽  
H. J. Oh ◽  
J. E. Park ◽  
M. J. Kim ◽  
E. J. Park ◽  
...  

Histocompatible tissue has been generated by somatic cell nuclear transfer (SCNT) and the resultant tissues were not rejected by the immune system of the nucleus donors. In addition, many transgenic animals combined with SCNT have been produced. However, in vitro immunogenicity of transgenic cloned animals originated from the same donor cell with nontransgenic cloned animals has not been assessed until now. The objective of this study was to evaluate the in vitro immunogenicity of cloned dogs with each other, between cloned dogs and transgenic cloned dogs and between transgenic cloned dogs with each other by mixed lymphocyte reaction. In this study, we used cloned beagles (BG1, 2) derived from SCNT using fetal fibroblasts (BF3). Serially, 4 transgenic cloned beagles (Ruppy 1–3, 5) were also genetically engineered from the same donor cell, BF3, with red fluorescent protein (RFP) gene inserted into their genome. We used 2 age-matched healthy female beagle dogs as control dogs. They have different 3 DLA types with all cloned dogs. Peripheral blood mononuclear cells (PBMC) of 2 cloned beagles and 4 transgenic cloned beagles were isolated from whole bloods using Ficoll gradient solution. PBMC from each dog were mixed to auto PBMC, other transgenic cloned dogs and non-related control dogs under the experimental designs. All the mixtures were incubated at 37°C for 4 days, adding BrdU labeling reagent and re-incubated for 24 h. Results are expressed in absorbance mean value ± standard deviation of 450-nm wavelength read by microplate reader. Each cell combination was assayed in 8 replicates. In Experiment 1, PBMC of cloned beagles were combined with equal concentrations of another cloned beagle's PBMC. In Experiment 2, PBMC suspension of Ruppy 1–3, 5 were mixed with equal concentrations of another transgenic cloned beagle's PBMC suspension. In Experiment 3, PBMC suspensions of cloned beagles were mixed with PBMC suspensions of transgenic cloned beagles and reverse reaction was performed. Statistical analysis was performed by using Mann-Whitney U test. In Experiment 1, whereas the absorbance value of mixture of cloned dogs and control dogs shows apparent proliferation, auto mixture of each dog and allo-mixture of BG1 and BG2 show no proliferation (Table 1), indicating immunological factors exposed to PBMC in 2 cloned dogs were compatible. In Experiment 2 among transgenic cloned dogs, no evidence of proliferations in mixed allo-PBMC was shown (Table 1), suggesting in vitro immunogenicity between transgenic cloned dogs was also not shown. In Experiment 3 among cloned dogs and transgenic cloned dogs, no significant difference was found (Table 1). In conclusion, cloned dogs derived from SCNT shared immunological phenotype. Next, immunogenicity among transgenic cloned beagle dogs was not shown despite random insertion of a foreign gene. Lastly, cloned beagles and transgenic cloned beagles show lymphocyte antigen compatibility irrespective of having a foreign gene or not. Table 1.The absorbance values of mixed lymphocytes of 4 transgenic cloned dogs and 2 cloned dogs This study was supported by RNL BIO (#0468-20110001), IPET, MKE (#10033839-2011-13) and Natural Balance Korea.


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