Improved production of GTKO/hCD55/hCD59 triple-gene-modified Diannan miniature pigs for xenotransplantation by recloning.

Multiple genetic modification is necessary for successful xenotransplantation from pigs. However, multiple-genetically modified cells usually suffer from various drug selections and long-term in vitro culture, which have a poor performance for somatic cell nuclear transfer (SCNT) to produce genetically modified pigs. We used to generate GTKO/hCD55/hCD59 triple-gene modified pigs by using drug-selective cell lines for SCNT, but the majority of cloned pigs were transgenic-negative individuals. In this study, to improve the production efficiency of multiple genetically modified pigs, we performed the recloning process by using transgenic porcine fetal fibroblast cells. As a result, two fetuses expressing hCD55 and hCD59 were obtained from 12 live-cloned fetuses, and one carrying high transgene expression was selected as a source of donor cells for recloning. Then we obtained 12 cloned piglets, all GTKO and carrying hCD55 and hCD59. Both hCD55 and hCD59 were expressed in fibroblast cells, but the expression levels of hCD55 and hCD59 were different among these piglets. Furthermore, piglet P5# had the highest expression of hCD55 and hCD59 in fibroblast cells than other piglets. Correspondingly, fibroblast cells of piglet P5# had significantly higher resistance against human serum-mediated cytolysis than those of piglet P11#. In conclusion, our results firstly provide support for improving efficiency of generating multiple genetically modified pig by recloning.

Generation of GHR-modified pigs as Laron syndrome models via a dual-sgRNAs/Cas9 system and somatic cell nuclear transfer.

BACKGROUND: Laron syndrome is an autosomal disease resulting from mutations in the growth hormone receptor (GHR) gene. The only therapeutic treatment for Laron syndrome is recombinant insulin-like growth factor I (IGF-I), which has been shown to have various side effects. The improved Laron syndrome models are important for better understanding the pathogenesis of the disease and developing corresponding therapeutics. Pigs have become attractive biomedical models for human condition due to similarities in anatomy, physiology, and metabolism relative to humans, which could serve as an appropriate model for Laron syndrome. METHODS: To further improve the GHR knockout (GHRKO) efficiency and explore the feasibility of precise DNA deletion at targeted sites, the dual-sgRNAs/Cas9 system was designed to target GHR exon 3 in pig fetal fibroblasts (PFFs). The vectors encoding sgRNAs and Cas9 were co-transfected into PFFs by electroporation and GHRKO cell lines were established by single cell cloning culture. Two biallelic knockout cell lines were selected as the donor cell line for somatic cell nuclear transfer for the generation of GHRKO pigs. The genotype of colonies, cloned fetuses and piglets were identified by T7 endonuclease I (T7ENI) assay and sequencing. The GHR expression in the fibroblasts and piglets was analyzed by confocal microscopy, quantitative polymerase chain reaction (q-PCR), western blotting (WB) and immunohistochemical (IHC) staining. The phenotype of GHRKO pigs was recapitulated through level detection of IGF-I and glucose, and measurement of body weight and body size. GHRKO F1 generation were generated by crossing with wild-type pigs, and their genotype was detected by T7ENI assay and sequencing. GHRKO F2 generation was obtained via self-cross of GHRKO F1 pigs. Their genotypes of GHRKO F2 generation was also detected by Sanger sequencing. RESULTS: In total, 19 of 20 single-cell colonies exhibited biallelic modified GHR (95%), and the efficiency of DNA deletion mediated by dual-sgRNAs/Cas9 was as high as 90% in 40 GHR alleles of 20 single-cell colonies. Two types of GHR allelic single-cell colonies (GHR-47/-1, GHR-47/-46) were selected as donor cells for the generation of GHRKO pigs. The reconstructed embryos were transferred into 15 recipient gilts, resulting in 15 GHRKO newborn piglets and 2 fetuses. The GHRKO pigs exhibited slow growth rates and small body sizes. From birth to 13 months old, the average body weight of wild-type pigs varied from 0.6 to 89.5 kg, but that of GHRKO pigs varied from only 0.9 to 37.0 kg. Biochemically, the knockout pigs exhibited decreased serum levels of IGF-I and glucose. Furthermore, the GHRKO pigs had normal reproduction ability, as eighteen GHRKO F1 piglets were obtained via mating a GHRKO pig with wild-type pigs and five GHRKO F2 piglets were obtained by self-cross of F1 generation, indicating that modified GHR alleles can pass to the next generation via germline transmission. CONCLUSION: The dual-sgRNAs/Cas9 is a reliable system for DNA deletion and that GHRKO pigs conform to typical phenotypes of those observed in Laron patients, suggesting that these pigs could serve as an appropriate model for Laron syndrome.

Efficient generation of P53 biallelic knockout Diannan miniature pigs via TALENs and somatic cell nuclear transfer.

BACKGROUND: Pigs have many features that make them attractive as biomedical models for various diseases, including cancer. P53 is an important tumor suppressor gene that exerts a central role in protecting cells from oncogenic transformation and is mutated in a large number of human cancers. P53 mutations occur in almost every type of tumor and in over 50% of all tumors. In a recent publication, pigs with a mutated P53 gene were generated that resulted in lymphoma and renal and osteogenic tumors. However, approximately 80% of human tumors have dysfunctional P53. A P53-deficient pig model is still required to elucidate. METHODS: Transcription activator-like effector nucleases (TALENs) were designed to target porcine P53 exon 4. The targeting activity was evaluated using a luciferase SSA recombination assay. P53 biallelic knockout (KO) cell lines were established from single-cell colonies of fetal fibroblasts derived from Diannan miniature pigs followed by electroporation with TALENs plasmids. One cell line was selected as the donor cell line for somatic cell nuclear transfer (SCNT) for the generation of P53 KO pigs. P53 KO stillborn fetuses and living piglets were obtained. Gene typing of the collected cloned individuals was performed by T7EI assay and sequencing. Fibroblast cells from Diannan miniature piglets with a P53 biallelic knockout or wild type were analyzed for the P53 response to doxorubicin treatment by confocal microscopy and western blotting. RESULTS: The luciferase SSA recombination assay revealed that the targeting activities of the designed TALENs were 55.35-fold higher than those of the control. Eight cell lines (8/19) were mutated for P53, and five of them were biallelic knockouts. One of the biallelic knockout cell lines was selected as nuclear donor cells for SCNT. The cloned embryos were transferred into five recipient gilts, three of them becoming pregnant. Five live fetuses were obtained from one surrogate by caesarean section after 38 days of gestation for genotyping. Finally, six live piglets and one stillborn piglet were collected from two recipients by caesarean section. Sequencing analyses of the target site confirmed the P53 biallelic knockout in all fetuses and piglets, consistent with the genotype of the donor cells. The qPCR analysis showed that the expression of the P53 mRNA had significant reduction in various tissues of the knockout piglets. Furthermore, confocal microscopy and western blotting analyses demonstrated that the fibroblast cells of Diannan miniature piglets with a P53 biallelic knockout were defective in mediating DNA damage when incubated with doxorubicin. CONCLUSION: TALENs combined with SCNT was successfully used to generate P53 KO Diannan miniature pigs. Although these genetically engineered Diannan miniature pigs had no tumorigenic signs, the P53 gene was dysfunctional. We believe that these pigs will provide powerful new resources for preclinical oncology and basic cancer research.

[Effect of genistein on MAPK signal pathway in the collagen-induced arthritis fibroblast-like synoviocytes].

OBJECTIVE: To study the effect of genistein (Gen) on MAPK signal pathway in the CIA rat fibroblast-like synoviocytes (FLS). METHODS: The rat model of collagen-induced arthritis (CIA) was established. The cultured FLS of CIA rats were divided using randomized method. The effects of Gen (at the concentration of 50, 100, and 200 micromol/L, respectively) on the proliferation of FLS in CIA rats using methyl thiazolyl tetrazolium (MTT) assay. Effects of Gen (at the concentration of 50, 100, and 200 pmol/L, respectively) on the expressions of extracellular signal-regulated kinase (ERK) and phosphorylated extracellular signal-regulated kinase (p-ERK) in the FLS of CIA rats were detected. RESULTS: Gen could inhibit the proliferation of FLS in CIA rats. The FLS proliferation in the high dose Gen group at 72 h was only 1.10+/-0.04, significantly lower than that in the model group (2.12+/-0.03, P<0.01). Besides, after Gen's action on FLS, the expression of p-ERK was down-regulated. It was only 0.34+/-0.02 in the high dose Gen group, significantly lower than that in the model group (2.68+/-0.14, P<0.01). There was no change in the expression of ERK (P>0.05). CONCLUSIONS: Gen could inhibit the proliferation of FLS in CIA rats. Its mechanism of action was mainly correlated to down-regulating the tyrosine kinase of MAPK signal transduction pathway and inhibiting phosphorylation of ERK.

[Anti-angiogenic effects of genistein on synovium in a rat model of type II collagen-induced arthritis].

OBJECTIVE: To explore the anti-angiogenic effects of genistein on synovium in a rat model of type II collagen-induced arthritis (CIA). METHODS: Forty SD rats were randomly divided into normal group, model group, genistein group, methotrexate (MTX) group and Gen plus MTX group with 8 rats in each group. Arthritis in rats was induced by subcutaneous injection of type II collagen combined with complete Freund's adjuvant (CFA). On the second day after the injection, 1 mL of suspension liquid of genistein (30 mg/kg body weight, once daily) and MTX (0.2 mg/kg body weight, once a week) were administered by oral gavage respectively. The rats in normal group and model group were administered with normal saline in the same volume. Synovium of knee joints and peripheral serum were collected from the CIA rats. Microvessel density in synovium (MVD) was detected by immunohistochemical method and serum vascular endothelial growth factor (VEGF) and matrix metallopeptidase (MMP)-1, 2 and 9 levels were detected by using Western blotting. RESULTS: Arthritis index score, paw volume of rats in the model group were significantly higher than those in the normal group (P<0.05), which suggested that a model of CIA induced by injection of type II collagen and CFA was successfully constructed. The arthritis index scores of rats in the treatment groups were decreased compared with the model group. The results of Western blotting showed that genistein obviously attenuate the levels of VEGF and MMP-1, 2 and 9 in serum (P<0.05). Immunohistochemical method showed that MVDs in the treatment groups were reduced as compared with the model group. CONCLUSION: The expressions of VEGF and MMP-1, 2 and 9 are related to the synovial pannus formation in CIA rats. The anti-angiogenic activity of genistein may correlate to its inhibitory effect on the expressions of VEGF and MMP-1, 2 and 9 in serum of CIA rats; genistein plus MTX are superior to single agents in treating rheumatoid arthritis.

[Effects of genistein on interleukin-1beta and tumor necrosis factor-alpha secreted by fibroblast-like synoviocytes isolated from type II collagen-induced arthritis rats].

OBJECTIVE: To investigate the effects of genistein (Gen) on interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) secreted by fibroblast-like synoviocytes (FLSs) of rats with type II collagen-induced arthritis (CIA). METHODS: Type II collagen was injected to induce arthritis in rats, and arthritis index was applied to evaluate whether the arthritis was induced successfully. The primary FLSs were separated from synovial membranes by using type II collagenase digestion. Then the expression of vascular cell adhesion molecule-1 (VCAM-1) was estimated by flow cytometry (FCM). After addition of different concentrations of Gen into the FLSs, IL-1beta and TNF-alpha contents in the supernatants were measured by enzyme-linked immunosorbent assay. RESULTS: Three days after collagen injection, the rats started to develop arthrocele and the arthritis index increased gradually. The arthritis index of CIA group was significantly higher than that of the control group. The expression of VCAM-1 was up to 85.5% in the 4th generation FLSs, indicating that most part of the cultured cells were type-B synoviocytes. After administration of different concentrations of Gen (100, 200, 400 micromol/L), the contents of IL-1beta and TNF-alpha in supernatants of FLSs were decreased dose-dependently. CONCLUSION: Genistein can suppress the secretion of TNF-alpha and IL-1beta in FLSs dose-dependently, which may be one of the mechanisms for genistein in inhibiting the arthromeningitis of CIA rats.

Generation of GTKO Diannan Miniature Pig Expressing Human Complementary Regulator Proteins hCD55 and hCD59 via T2A Peptide-Based Bicistronic Vectors and SCNT.

Pig-to-human organ transplantation has drawn attention in recent years due to the potential use of pigs as an alternative source of human donor organs. While GGTA1 knockout (GTKO) can protect xenografts from hyperacute rejection, complement-dependent cytotoxicity might still contribute to this type of rejection. To prolong the xenograft survival, we utilized a T2A-mediated pCMV-hCD55-T2A-hCD59-Neo vector and transfected the plasmid into GTKO Diannan miniature pig fetal fibroblasts. After G418 selection combined with single-cell cloning culture, four colonies were obtained, and three of these were successfully transfected with the hCD55 and hCD59. One of the three colonies was selected as donor cells for somatic cell nuclear transfer (SCNT). Then, the reconstructed embryos were transferred into eight recipient gilts, resulting in four pregnancies. Three of the pregnant gilts delivered, yielding six piglets. Only one piglet carried hCD55 and hCD59 genetic modification. The expression levels of the GGTA1, hCD55, and hCD59 in the tissues and fibroblasts of the piglet were determined by q-PCR, fluorescence microscopy, immunohistochemical staining, and western blotting analyses. The results showed the absence of GGTA1 and the coexpression of the hCD55 and hCD59. However, the mRNA expression levels of hCD55 and hCD59 in the GTKO/hCD55/hCD59 pig fibroblasts were lower than that in human 293T cells, which may be caused by low copy number and/or CMV promoter methylation. Furthermore, we performed human complement-mediated cytolysis assays using human serum solutions from 0 to 60%. The result showed that the fibroblasts of this triple-gene modified piglet had greater survival rates than that of wild-type and GTKO controls. Taken together, these results indicate that T2A-mediated polycistronic vector system combined with SCNT can effectively generate multiplex genetically modified pigs, additional hCD55 and hCD59 expression on top of a GTKO genetic background markedly enhance the protective effect towards human serum-mediated cytolysis than those of GTKO alone. Thus, we suggest that GTKO/hCD55/hCD59 triple-gene-modified Diannan miniature pig will be a more eligible donor for xenotransplantation.