The potential of genetically-engineered pigs in providing an alternative source of organs and cells for transplantation

There is a critical shortage of organs, cells, and corneas from deceased human donors worldwide. There are also shortages of human blood for transfusion. A potential solution to all of these problems is the transplantation of organs, cells, and corneas from a readily available animal species, such as the pig, and the transfusion of red blood cells from pigs into humans. However, to achieve these ends, major immunologic and other barriers have to be overcome. Considerable progress has been made in this respect by the genetic modification of pigs to protect their tissues from the primate immune response and to correct several molecular incompatibilities that exist between pig and primate. These have included knockout of genes responsible for the expression of major antigenic targets for primate natural anti-pig antibodies, insertion of human complement- and coagulation-regulatory transgenes, and knockdown of swine leukocyte antigens that stimulate the primate＇s adaptive immune response. As a result of these manipulations, the administration of novel immunosuppressive agents, and other innovations, pig hearts have now functioned in baboons for 6-8 months, pig islets have maintained normoglycemia in diabetic monkeys for 〉 1 year, and pig corneas have maintained transparency for several months. Clinical trials of pig islet trans- plantation are already in progress. Future developments will involve further genetic manipulations of the organ- source pig, with most of the genes that are likely to be beneficial already identified.

Antigenicity of tissues and organs from GGTA1/CMAH/β4GalNT2 triple gene knockout pigs

Clinical xenotransplantations have been hampered by human preformed antibody-mediated damage of the xenografts.To overcome biological incompatibility between pigs and humans,one strategy is to remove the major antigens[Gal,Neu5 Gc,and Sd(a)]present on pig cells and tissues.Triple gene(GGTAI,CMAH,and β4 GalNT2)knockout(TKO)pigs were produced in our laboratory by CRISPR-Cas9 targeting.To investigate the antigenicity reduction in the TKO pigs,the expression levels of these three xenoantigens in the cornea,heart,liver,spleen,lung,kidney,and pancreas tissues were examined.The level of human IgG/IgM binding to those tissues was also investigated,with wildtype pig tissues as control.The results showed that aGal,Neu5 Gc,and Sd(a)were markedly positive in all the examined tissues in wildtype pigs but barely detected in TKO pigs.Compared to wildtype pigs,the liver,spleen,and pancreas of TKO pigs showed comparable levels of human IgG and IgM binding,whereas corneas,heart,lung,and kidney of TKO pigs exhibited significantly reduced human IgG and IgM binding.These results indicate that the antigenicity of TKO pig is significantly reduced and the remaining xenoantigens on porcine tissues can be eliminated via a gene targeting approach.

Endothelin-1-induced mini-stroke in the dorsal hippocampus or lateral amygdala results in deficits in learning and memory

Functional and structural alterations in brain connectivity associated with brain ischemia have been extensively studied. However, the mechanism whereby local ischemia in deep brain region affect brain functions is still unknown. Here, we first established a mini-stroke model by infusion of endothelin-1 （ET-1） into the dorsal hippo- campus or the lateral amygdala, and then investigated how these mini-infarcts affected brain functions associated with these regions. We found that rats with ET-1 infusion showed deficit in recall of contextual fear memory, but not in learning process and recall of tone fear memory. In novel object task, ET-1 in the hippocampus also elimi- nated object identity memory. ET-1 in the lateral amygdale affected acquisition of fear conditioning and disrupted retention of tone-conditioned fear, but did not impair retention of contextual fear. These findings suggest that ET-1- induced mini-infarct in deep brain area leads to functional deficits in learning and memory associated with these regions.

Unbalanced omega-6/omega-3 ratio in red meat products in China

Dietary meats play a crucial role in human health. The objective of this survey was to determine the fatty acid content and omega-6/omega-3 polyunsaturated fatty acids （n-6/n-3 PUFA） ratio of fresh red meat （beef and pork） from four cities （Shanghai, Nanjing, Yinchuan and Hohhot） in China. The results showed that the n-6/n-3 PUFA ratio from all the samples ranged from 6 to 23. The total n-6 PUFA concentrations ranged from 290.54 mg/100 g in beef from Nanjing to 1601.48 mg/100 g in pork from Hohhot, whereas the total concentrations of n-3 PUFA ranged from 46.34 mg/100 g in beef from Nanjing to 96.03 mg/100 g in pork from Nanjing. The results indicated that the n-6/n-3 ratio in the red meat from all four regions is unbalanced and is much higher than that （〈 5：1） rec- ommended by the WHO/FAO. The total amount of n-3 PUFA was far lower than the required daily dose. There- fore, potential solutions to increase the n-3 PUFA content in meat products or to provide alternative source of n-3 PUFA should be explored.

Generation of monoclonal antibodies against n-3 fatty acid desaturase

Dear Editor： Omega-3 polyunsaturated fatty acids （n-3 PUFAs） are essential fatty acids for normal cellular functions and have been used for prevention and treatment of many diseases, including coronary heart disease, dia- betes, and cancers. n-3 PUFAs and n-6 PUFAs have been shown to decrease and increase the severity of several human diseases, respectively. Unfortunately,

Protective effects on acute hypoxic-ischemic brain damage in mfat-1 transgenic mice by alleviating neuroinflammation

Acute hypoxic-ischemic brain damage(HIBD)mainly occurs in adults as a result of perioperative cardiac arrest and asphyxia.The benefits of n-3 polyunsaturated fatty acids(n-3 PUFAs)in maintaining brain growth and development are well documented.However,possible protective targets and underlying mechanisms of mfat-1 mice on HIBD require further investigation.The mfat-1 transgenic mice exhibited protective effects on HIBD,as indicated by reduced infarct range and improved neurobehavioral defects.RNA-seq analysis showed that multiple pathways and targets were involved in this process,with the anti-inflammatory pathway as the most significant.This study has shown for the first time that mfat-1 has protective effects on HIBD in mice.Activation of a G protein-coupled receptor 120(GPR120)-related anti-inflammatory pathway may be associated with perioperative and postoperative complications,thus innovating clinical intervention strategy may potentially benefit patients with HIBD.

Dominant-negative inhibition of glucose-dependent insulinotropic polypeptide impairs function of β cells in transgenic pigs

Dear Editor： Glucose-dependent insulinotropic polypeptide （GIP） and proglucagon product glucagon-like peptide-1 （GLP- 1） and their corresponding receptors promote secretion of glucose-dependent insulin and may be responsible for up to 70% of postprandial insulin secretions.

Induction of diabetes in cynomolgus monkey with one shot of analytical grade streptozotocin

Backgrounds:Streptozotocin(STZ)-induced diabetic monkey is a wide used preclinical animal model for the investigation of diabetes such as islet transplantation and development of diabetic drugs.There are serious side effects of this method,including nausea,emesis,weight loss,liver damage,renal failure,and metabolic acidosis.In order to reduce the side effects,diabetic monkeys were induced using clinicalgrade STZ.However,clinical-grade STZ is not available in China.Here,we establised a method by using 100 mg/kg analytical-grade STZ to induce complete diabetes in cynomolgus monkey without generating adverse effects to liver and renal.Methods:Three cynomolgus monkeys were used in this study.100 mg/kg STZ dissolved in normal saline and infused through vein line in 5 minutes after indwelling catheter in the carotid artery and jugular vein.After the STZ administration,blood glucose levels were examined every 1 or 2 hours in the first 48 hours.Then,blood glucose levels were examined twice per day during the first week after the STZ injection.Insulin and C-peptide levels were measured by ELISA.Blood chemistry of hepatic and renal function tests were performed.Insulin and glucagon expression in the islet of diabetic monkey and normal monkey were examined by immunohistochemistry assays.Results:The stimulated C-peptide level(Intravenous glucose tolerance test)which is less than 0.5 ng/mL,the triphasic blood glucose response and the destroyed β cell suggested the complete induction of diabetes model.No apparent adverse effects were observed including no signs of vomiting and toxicity after STZ injection.Conclusion:In summary,we established a safe and reproducible STZ-induced diabetic cynomolgus monkey model for islet transplantation which will be used to develop novel approaches for the treatment of diabetes.

Generation of B Cell-Deficient Pigs by Highly Efficient CRISPR/Cas9-Mediated Gene Targeting

Generating B cell-deficient mutant is the first step to produce human antibody repertoires in large animal models. In this study, we applied the clustered regularly interspaced short palindromic repeat （CRISPR）/CRISPR-associated （Cas） system to target the JH region of the pig IgM heavy chain gene which is crucial for B cell development and differentiation. Transfection of IgM-targeting Cas9 plasmid in primary porcine fetal fibroblasts （PFFs） enabled inducing gene knock out （KO） in up to 53.3% of colonies analyzed, a quarter of which harbored biallelic modification, which was much higher than that of the traditional homologous recombination （HR）. With the aid of somatic cell nuclear transfer （SCNT） technology, three piglets with the biallelic lgM heavy chain gene mutation were produced. The piglets showed no antibody-producing B cells which indicated that the biallelic mutation of the lgM heavy chain gene effectively knocked out the function of the IgM and resulted in a B cell-deficient phenotype. Our study suggests that the CRISPR/Cas9 system combined with SCNT technology is an efficient genome-editing approach in pigs.

OSBPL2-disrupted pigs recapitulate dual features of human hearing loss and hypercholesterolaemia

Oxysterol binding protein like 2(OSBPL2), an important regulator in cellular lipid metabolism and transport, was identified as a novel deafness-causal gene in our previous work. To resemble the phenotypic features of OSBPL2 mutation in animal models and elucidate the potential genotypephenotype associations, the OSBPL2-disrupted Bama miniature(BM) pig model was constructed using CRISPR/Cas9-mediated gene editing, somatic cell nuclear transfer(SCNT) and embryo transplantation approaches, and then subjected to phenotypic characterization of auditory function and serum lipid profiles. The OSBPL2-disrupted pigs displayed progressive hearing loss(HL) with degeneration/apoptosis of cochlea hair cells(HCs) and morphological abnormalities in HC stereocilia, as well as hypercholesterolaemia. High-fat diet(HFD) feeding aggravated the development of HL and led to more severe hypercholesterolaemia. The dual phenotypes of progressive HL and hypercholesterolaemia resembled in OSBPL2-disrupted pigs confirmed the implication of OSBPL2 mutation in nonsydromic hearing loss(NSHL) and contributed to the potential linkage between auditory dysfunction and dyslipidaemia/hypercholesterolaemia.

A Bama miniature pig model of monoallelic TSC1 mutation for human tuberous sclerosis complex

Tuberous sclerosis complex(TSC)is a dominant genetic neurocutaneous syndrome characterized by multiple organ hamartomas.Although rodent models bearing a germline mutation in either TSC1 or TSC2 gene have been generated,they do not develop pathogenic lesions matching those seen in patients with TSC because of the significant differences between mice and humans,highlighting the need for an improved large animal model of TSC.Here,we successfully generate monoallelic TSC1-modified Bama miniature pigs using the CRISPR/Cas9 system along with somatic cell nuclear transfer(SCNT)technology.The expression of phosphorylated target ribosomal protein S6 is significantly enhanced in the piglets,indicating that disruption of a TSC1 allele activate the mechanistic target of rapamycin(mTOR)signaling pathway.Notably,differing from the mouse TSC models reported previously,the TSC1^(+/−)Bama miniature pig developed cardiac rhabdomyoma and subependymal nodules,resembling the major clinical features that occur in patients with TSC.These TSC1^(+/−)Bama miniature pigs could serve as valuable large animal models for further elucidation of the pathogenesis of TSC and the development of therapeutic strategies for TSC disease.

Overexpressing dominant-negative FGFR2-IIIb impedes lung branching morphogenesis in pigs

Genetic studies with mouse models have shown that fibroblast growth factor receptor 2-Ⅲb（FGFR2-Ⅲb）plays crucial roles in lung development and differentiation. To evaluate the effect of FGFR2-Ⅲb in pig lung development, we employed somatic cell nuclear transfer（SCNT） technology to generate transgenic pig fetuses overexpressing the transmembrane（dn FGFR2-Ⅲb-Tm） and soluble（dn FGFR2-Ⅲb-HFc） forms of the dominant-negative human FGFR2-Ⅲb driven by the human surfactant protein C（SP-C） promoter,which was specifically expressed in lung epithelia. Eight dn FGFR2-Ⅲb-Tm transgenic and twelve dn FGFR2-Ⅲb-HFc transgenic pig fetuses were collected from three and two recipient sows, respectively.Repression of FGFR2-Ⅲb in lung epithelia resulted in smaller lobes and retardation of alveolarization in both forms of dn FGFR2-Ⅲb transgenic fetuses. Moreover, the dn FGFR2-Ⅲb-HFc transgenic ones showed more deterioration in lung development. Our results demonstrate that disruption of FGFR2-Ⅲb signaling in the epithelium impedes normal branching and alveolarization in pig lungs, which is less severe than the results observed in transgenic mice. The dn FGFR2-Ⅲb transgenic pig is a good model for the studies of blastocyst complementation as well as the mechanisms of lung development and organogenesis.

Research on the evaluation model and demonstration of patentee's discourse power:A case study of cyber security

With the deep meaning of discourse power in international relations,national discourse power has become an important manifestation of national soft power.This paper analyzes the main elements of the discourse power of patentee to speak,constructs the evaluation model,and selects the evaluation indexes related to the six characteristics according to the methods of patent measurement and social network analysis.In the empirical research stage,taking the field of network security as an example,the validity and reliability of the evaluation system are tested,and the accuracy of the evaluation results is tested by correlation.It is found that the evaluation system of discourse power of patentee to speak in the field of network security proposed in this paper is effective.

Ion beam figuring of continuous phase plates based on the frequency filtering process

Ion beam figuring （IBF） technology is an effective technique for fabricating continuous phase plates （CPPs） with small feature structures. This study proposes a multi-pass IBF approach with different beam diameters based on the frequency filtering method to improve the machining accuracy and efficiency of CPPs during IBF. We present the selection principle of the frequency filtering method, which incorporates different removal functions that maximize material removal over the topographical frequencies being imprinted. Large removal functions are used early in the fabrication to figure the surface profile with low frequency. Small removal functions are used to perform final topographical correction with higher fre- quency and larger surface gradient. A high-precision surface can be obtained as long as the filtering frequency is suitably selected. This method maximizes the high removal efficiency of the large removal function and the high corrective capability of the small removal function. Consequently, the fast convergence of the machining accuracy and efficiency can be achieved.

Factors in?uencing the somatic cell nuclear transfer ef?ciency in pigs

Using a data set from our laboratory, we assessed the effects of several factors on pig cloning ef?ciency. The results demonstrated that cells at high con?uence( > 90%) used as donor cell resulted in higher pregnancy rate, delivery rate and overall cloning ef?ciency(number of live offspring born per reconstructed embryo transferred to recipients) compared with the cells at 60% to79% con?uence and 80% to 89% con?uence. Cells with four, ?ve and six passages compromised the pregnancy and delivery rates compared with ?rst passage cells. The number of blastocysts transferred by somatic cell nuclear transfer(SCNT) did not signi?cantly affect the cloning ef?ciency, but transfer of blastocyst derived from in vitro culture 5 d after SCNT achieved a signi?cantly higher pregnancy rate compared with one to two cell SCNT embryos from overnight culture. The highest pregnancy rate, delivery rate and the largest litter size were obtained when Bama Miniature pig ?broblasts were used as donor cells and Landrace/Yorkshire hybrid gilts were used as recipients. Recipients treated with chemicals for estrus synchronization had higher pregnancy rates compared with untreated recipients. Our data might be helpful for improving SCNT ef?ciency in pigs.

Erratum to“A Bama miniature pig model of monoallelic TSC1 mutation for human tuberous sclerosis complex”[Journal of Genetics and Genomics(2020)47,735–742]

This erratum clarifies information in the article“A Bama miniature pig model of monoallelic TSC1 mutation for human tuberous sclerosis complex”by Li et al.(2020).In the“Acknowledgment”section,the statement that“This work was supported by grants from the National Natural Science Foundation of China(31701283,81970164)”should say“This work was supported by grants from the National Natural Science Foundation of China(81874144,81970164)”.