In general, cloned pigs have been produced using the somatic cell nuclear transfer (SCNT) technique with various types of somatic cells; however, the SCNT technique has disadvantages not only in its low efficiency but also in the development of abnormal clones. This study aimed to compare early embryonic development and quality of SCNT embryos with those of induced pluripotent stem cells (iPSCs) NT embryos (iPSC-NTs). Ear fibroblast cells were used as donor cells and iPSCs were generated from these cells by lentiviral transduction with human six factors (Oct4, Sox2, c-Myc, Nanog, Klf4 and Lin28). Blastocyst formation rate in iPSC-NT (23/258, 8.9%) was significantly lower than that in SCNT (46/175, 26.3%; p < 0.05). Total cell number in blastocysts was similar between two groups, but blastocysts in iPSC-NT had a lower number of apoptotic cells than in SCNT (2.0 ± 0.6 vs. 9.8 ± 2.9, p < 0.05). Quantitative PCR data showed that apoptosis-related genes (bax, caspase-3, and caspase-9) were highly expressed in SCNT than iPSC-NT (p < 0.05). Although an early development rate was low in iPSC-NT, the quality of cloned embryos from porcine iPSC was higher than that of embryos from somatic cells. Therefore, porcine iPSCs could be used as a preferable cell source to create a clone or transgenic animals by using the NT technique.

Pigs are considered as optimal donor animal for the successful xenotransplantation. To increase the possibility of clinical application, genetic modification to increase compatibility with human is an important and essential process. Genetic modification technique has been developed and improved to produce genetically modified pigs rapidly. CRISPR/Cas9 system is widely used in various fields including the production of transgenic animals and also can be enable multiple gene modifications. In this study, we developed new gene targeting vector and enrichment system for the rapid and efficient selection of genetically modified cells. We conducted co-transfection with two targeting vectors for simultaneous inactivation of two genes and enrichment of the genetically modified cells using MACS. After this efficient enrichment, genotypic analysis of each colony showed that colonies which have genetic modifications on both genes were confirmed with high efficiency. Somatic cell nuclear transfer was conducted with established donor cells and genetically modified pigs were successfully produced. Genotypic and phenotypic analysis of generated pigs showed identical genotypes with donor cells and no surface expression of α-Gal and HD antigens. Furthermore, functional analysis using pooled human serum revealed dramatically reduction of human natural antibody (IgG and IgM) binding level and natural antibody-mediated cytotoxicity. In conclusion, the constructed vector and enrichment system using MACS used in this study is efficient and useful to generate genetically modified donor cells with multiple genetic alterations and lead to an efficient production of genetically modified pigs.

Although the majority of surviving pigs cloned by somatic cell nuclear transfer (SCNT) appear to be physiologically normal, there is a general lack of detailed hemato-physiologic studies for the period of early adulthood to substantiate this claim. In the present study, we investigated variation in blood chemistry and endocrinological parameters between mesenchymal stem cells (MSCs) derived from cloned and normal age-matched female and male miniature pigs. Cloned females and males showed normal ranges for complete blood count assessments. Biochemical assessments showed that γ-GGT, ALT and cholesterol levels of male and female clones were significantly (P<0.05 or P<0.01, respectively) higher than that of age-matched control miniature pigs. Variations in insulin and IGF-1 were higher in female clones than in male clones and controls. Thus, although female and male cloned miniature pigs may be physiologically similar to normal animals, or at least within normal ranges, a greater degree of physiological and endocrinological variation was found in cloned pigs. The above variation must be taken into account before considering cloned female or male miniature pigs for various biomedical applications.

In order to investigate genetic stability and gene expression profile after cloning procedure, two groups of cloned pigs were used for swine leukocyte antigen (SLA) gene nucleotide alteration and microarray analyses. Each group was consist of cloned pigs derived from same cell line (n=3 and 4, respectively). Six SLA loci were analyzed for cDNA sequences and protein translations. In total, 16 SLA alleles were identified and there were no evidence of SLA nucleotide alteration. All SLA sequences and protein translations were identical among the each pig in the same group. On the other hand, microarray assay was performed for profiling gene expression of the cloned pigs. In total, 43,603 genes were analyzed and 2,150～4,300 reliably hybridized spots on the each chip were selected for further analysis. Even though the cloned pigs in the same group had identical genetic background, 18.6～47.3% of analyzed genes were differentially expressed in between each cloned pigs. Furthermore, on gene clustering analysis, some cloned pigs showed abnormal physiological phenotypes such as inflammation, cancer or cardiomyopathy. We assumed that individual environmental adaption, sociality and rank in the pen might have induced these different phenotypes. In conclusion, the results of the present study indicate that SLA locus genes appear to be stable following SCNT. However, gene expressions and phenotypes between cloned pigs derived from the same cell line were not identical even under the same rearing conditions.

Pig parthenotes were able to develop in vivo for 30 days with normal morphology. In pig, during blastocyst elongation between day 10 and 12 of gestation, estrogen production and secretion by conceptus increases, serving not only as the signal for maternal recognition of pregnancy, but also as a stimulus for the production of proteins and growth factors within the uterine environment that initiate implantation. Cloning efficiency is still very low regardless of species. To increase the productive efficiency of (transgenic, TG) clones, an advanced somatic cell nuclear transfer (SCNT) method may need. Here we report the productions of transgenic cloned pigs using cloned embryos and parthenotes simultaneously. Fibroblasts were isolated from an ear skin of a 10‐day‐old NIH miniature pig. The ear fibroblast cells were transfected with the alpha1,3‐ Galactosyltransferase knock‐out/human CD46 knock‐in (GalT KO/hCD46 KI). For SCNT, the TG somatic cells were used as donor cells. Immediately after fusion confirmation, the TG cloned embryos and parthenotes were transferred into both oviducts of surrogates. The mean number of TG cloned embryos and parthenotes was 137 (±15.2) and 123(±27.1), respectively. The pregnancy and delivery rate was (55.6%, 10/ 18) (44.4%, 8/18), respectively. Totally 19 GalT KO/hCD46 KI cloned piglets were delivered. Among them, 11 piglets were survived and 8 piglets were born stillbirth. The healthy 5 piglets are still survived.

Although the National Institute of Health (NIH, USA) miniature pigs were developed specifically for xenotransplantation, the cloning efficiency is still very low. To increase the efficiency, an advanced somatic cell nuclear transfer (SCNT) method may need. In the present study, we report the productions of genetically modified cloned pigs using the frozen-thawed donor cells without culture before SCNT. Fibroblasts were isolated from an ear skin of a 10-day-old NIH miniature pig. The fibroblast cells were genetically modified with the human CD73 (hCD73). For SCNT, somatic cells transfected with hCD73 were used as donor cells. The survival rate of the somatic cells was significantly higher in 0 h (95%) compared with 1 h (81%) after thawing (p<0.05). We obtained the pregnancy (38.9%, 7/18) and delivery (11.1%, 2/18) rate, respectively. Totally 7 genetically modified cloned piglets were delivered. Among them, 2 piglets were survived and 5 piglets were born stillbirth. The healthy 2 piglets are still survived (≥6 months).

The present study investigated the physiological evaluation of cloned mini-pigs in a transportable isolator. Transportable isolator was designed and manufactured by our research team for transporting gnotobiotic pig. Until now, no previous reports are available regarding the physiological activities and harmful effects when pigs were transported in this isolator. Five cloned mini-pigs of 1~2 year (s) old female with a body weight between 80~90 kg were used. The effects of transportable isolator on stress-related hormone, adrenocorticotrophic hormone (ACTH) and cortisol levels, and heart rate were evaluated. In addition, it was also examined the effects of transportable isolator on blood chemistry factors (alanine aminotransferase: ALT, aspartate aminotransferase: AST, blood urea nitrogen: BUN, glucose, and creatinine). Blood was sampled just before the beginning of transport (T0), at the end of transport (30min after the transport; T1), and 30 min after the end of transport (T2). At the same time, heart rate was also evaluated. As a result, heart rate had no significant (p>0.05) differences at the various-time points of study (T0, T1, T2). However, heart rate was slightly higher than normal range in T1 and T2. The ACTH level was higher than normal range. Whereas, the cortisol level was lower than normal range. There were no statistical significant differences both ACTH and cortisol level between different time groups. Also, there were no significant differences in blood chemistry factors. Therefore, our present study shows that transportable isolator has no harmful effect on stress and physiological condition in cloned mini-pigs.

One of the reasons to causing blood coagulation in the tissue of xenografted organs was known to incompatibility of the blood coagulation and anti-coagulation regulatory system between TG pigs and primates. Thus, overexpression of human CD73 (hCD73) in the pig endothelial cells is considered as a method to reduce coagulopathy after pig-to-non-humanprimate xenotransplantation. This study was performed to produce and breed transgenic pigs expressing hCD73 for the studies immune rejection responses and could provide a successful application of xenotransplantation. The transgenic cells were constructed an hCD73 expression vector under control porcine Icam2 promoter (pIcam2-hCD73) and established donor cell lines expressing hCD73. The numbers of transferred reconstructed embryos were 127 ± 18.9. The pregnancy and delivery rate of surrogates were 8/18 (44%) and 3/18 (16%). The total number of delivered cloned pigs were 10 (2 alive, 7 mummy, and 1 died after birth). Among them, three live hCD73-pigs were successfully delivered by Caesarean section, but one was dead after birth. The two hCD73 TG cloned pigs had normal reproductive ability. They mated with wild type (WT) MGH (Massachusetts General Hospital) female sows and produced totally 16 piglets. Among them, 5 piglets were identified as hCD73 TG pigs. In conclusion, we successfully generated the hCD73 transgenic cloned pigs and produced their litters by natural mating. It can be possible to use a mate for the production of multiple transgenic pigs such as α-1,3-galactosyltransferase knock-out /hCD46 for xenotransplantation.