Monitoring Porcine Cytomegalovirus in Both Donors and Recipients is Crucial for Recipient's Survival in Pig-to-Cynomolgus Xenotransplantation.

BACKGROUND: Xenotransplantation, particularly when involving pig donors, presents challenges related to the transmission of porcine cytomegalovirus (pCMV) and its potential impact on recipient outcomes. This study aimed to investigate the relationship between pCMV positivity in both donors and recipients and the survival time of cynomolgus monkey recipients after xenogeneic kidney transplantation. METHODS: We conducted 20 cynomolgus xenotransplants using 18 transgenic pigs. On the surgery day, donor pig blood was sampled, and DNA was extracted from serum and peripheral blood mononuclear cells. Recipient DNA extraction followed the same protocol from pre-transplantation to post-transplantation. Porcine cytomegalovirus detection used real-time polymerase chain reaction (real-time PCR) with the ViroReal kit, achieving a sensitivity of 50 copies/reaction. A Ct value of 37.0 was the pCMV positivity threshold. RESULTS: Of 20 cynomolgus recipients, when donors tested negative for pCMV, recipients also showed negative results in 9 cases. In 4 cases where donors were negative, recipients tested positive. All 5 cases with pCMV-positive donors resulted in positive assessments for recipients. Detection of donor pCMV correlated with shorter recipient survival. Continuous recipient positivity during observation correlated with shorter survival, whereas transient detection showed no significant change in survival rates. However, donor pig phenotypes and transplantation protocols did not significantly impact survival. CONCLUSION: The detection of pCMV in both donors and recipients plays a crucial role in xenotransplantation outcomes. These findings suggest the importance of monitoring and managing pCMV in xenotransplantation to enhance long-term outcomes.

Analysis of production efficiency of cloned transgenic Yucatan miniature pigs according to recipient breeds with embryo transfer conditions.

The purpose of this study was to compare the efficiency of the production of cloned transgenic Yucatan miniature pigs (YMPs) using two recipient breeds, i.e., YMPs and domestic pigs (DPs), under various embryo transfer conditions. We initially assessed the in vitro developmental competence of embryos obtained via somatic cell nuclear transfer (SCNT) from three different transgenic donor cells. No difference was observed among the three groups regarding developmental competence. Furthermore, the cloning efficiency remained consistent among the three groups after the transfer of the SCNT embryos to each surrogate mother. Subsequently, to compare the efficiency of the production of cloned transgenic YMPs between the two recipient breeds using varying parameters, including ovulation status (preovulation and postovulation), duration of in vitro culture (IVC) (incubated within 24 h and 24-48 h), and the number of transferred SCNT embryos (less than and more than 300), we assessed the pregnancy rates, delivery rates, mean offspring counts, and cloning efficiency. Regarding the ovulation status, YMPs exhibited higher pregnancy rates, delivery rates, and cloning efficiency compared with DPs in both statuses. Moreover, the pregnancy rates, delivery rates, and cloning efficiency were affected by the ovulation status in DPs, but not in YMPs. The comparison of IVC duration between groups revealed that YMPs had higher pregnancy rates vs. DPs in both conditions. SCNT embryos cultured for 24-48 h in YMPs yielded higher delivery rates and cloning efficiency compared with those cultured for less than 24 h in DPs. Finally, the analysis based on the number of transferred SCNT embryos showed that both the pregnancy and delivery rates were higher in YMPs vs. DPs. However, the highest average number of offspring was obtained when more than 300 SCNT embryos were transferred into DPs, whereas the cloning efficiency was higher in YMPs vs. DPs. Our results suggest that YMPs are more suitable recipients than are DPs under various conditions for the production of cloned transgenic YMPs.

A Comparison Between GalT-/-;hCD39;hCD55 and GalT-/-;hCD39;hCD46;hCD55;TBM Pig Kidneys Transplanted in Nonhuman Primates.

Because there is a shortage of donor kidneys, researchers are exploring the possibility of using genetically modified pig kidneys for transplantation. Approaches involving knockout of carbohydrate genes or knockin of protective proteins have been attempted to determine the best gene modifications. In this study, we utilized GalT-/-;hCD39;hCD55 and GalT-/-;hCD39;hCD46;hCD55;thrombomodulin (TBM) pigs for transplantation in nonhuman primates (NHPs). The NHPs survived for 4 weeks after kidney transplantation (4 WAT) from the GalT-/-;hCD39;hCD55 pig and for 6 WAT from the GalT-/-;hCD39;hCD46;hCD55;TBM pig. However, messenger RNA (mRNA) sequencing and immunohistochemistry analysis revealed that the 6 WAT kidney exhibited more severe apoptosis, inflammation, loss of renal function, and renal fibrosis than the 4 WAT kidney. These results indicate that additional knockin of complement regulator (hCD46) and coagulation regulator (TBM) is not enough to prevent renal damage, suggesting that improved immune suppression is needed for more prolonged survival.

Alteration of γδ T cell subsets in non-human primates transplanted with GGTA1 gene-deficient porcine blood vessels.

BACKGROUND: αGal-deficient xenografts are protected from hyperacute rejection during xenotransplantation but are still rejected more rapidly than allografts. Despite studies showing the roles of non-Gal antibodies and αß T cells in xenograft rejection, the involvement of γδ T cells in xenograft rejection has been limitedly investigated. METHODS: Six male cynomolgus monkeys were transplanted with porcine vessel xenografts from wild-type (n = 3) or GGTA1 knockout (n = 3) pigs. We measured the proportions and T cell receptor (TCR) repertoires of blood γδ T cells before and after xenotransplant. Grafted porcine vessel-infiltrating immune cells were visualized at the end of experiments. RESULTS: Blood γδ T cells expanded and infiltrated into the graft vessel adventitia following xenotransplantation of α-Gal-deficient pig blood vessels. Pre- and post-transplant analysis of γδ TCR repertoire revealed a transition in δ chain usage post-transplantation, with the expansion of several clonotypes of δ1, δ3, or δ7 chains. Furthermore, the distinctions between pre- and post-transplant δ chain usages were more prominent than those observed for γ chain usages. CONCLUSION: γδ TCR repertoire was significantly altered by xenotransplantation, suggesting the role of γδ T cells in sustained xenoreactive immune responses.

Initial investigation on the feasibility of porcine red blood cells from genetically modified pigs as an alternative to human red blood cells for transfusion.

The decline in blood donation rates and the ongoing shortage of blood products pose significant challenges to medical societies. One potential solution is to use porcine red blood cells (pRBCs) from genetically modified pigs as an alternative to human red blood cells (hRBCs). However, adverse immunological reactions remain a significant obstacle to their use. This study aimed to evaluate the compatibility of diverse genetically modified pRBCs with human serum. We acquired human complement-competent serum, complement 7 (C7)-deficient serum, and hRBCs from all ABO blood types. Additionally, we used leftover clinical samples from health checkups for further evaluation. pRBCs were collected from wild-type (WT) and genetically modified pigs: triple knockout (TKO), quadruple KO (QKO), and TKO/hCD55.hCD39 knockin (hCD55.hCD39KI). The extent of C3 deposition on RBCs was measured using flow cytometry after incubation in C7-deficient serum diluted in Ca++-enriched or Ca++-depleted and Mg++-enriched buffers. The binding of immunoglobulin (Ig) M/IgG antibody to RBCs after incubation in ABO-type human serum was evaluated using flow cytometry. Naïve human serum- or sensitized monkey serum-mediated hemolysis was also evaluated. Phagocytosis was assessed by incubating labeled RBCs with the human monocytic cell line THP-1 and measurement by flow cytometry. All three genetic modifications significantly improved the compatibility of pRBCs with human serum relative to that of WT pRBCs. The extent of IgM/IgG binding to genetically modified pRBCs was lower than that of WT pRBCs and similar to that of O-type hRBCs. Total and alternative pathway complement activation in all three genetically modified pRBCs was significantly weaker than that in WT pRBCs and did not differ from that in O-type hRBCs. The extent of serum-mediated hemolysis and phagocytosis of these genetically modified pRBCs was low and similar to that of O-type hRBCs. Sensitized monkey serum-mediated hemolysis in QKO and TKO/hCD55.hCD39KI pRBCs was higher than in O-type hRBCs but lower than in TKO pRBCs. The elimination of porcine carbohydrate antigens in genetically modified pigs significantly enhanced pRBC compatibility with naïve human sera, which was comparable to that of O-type hRBCs. These findings provide valuable insights into the development of pRBCs as potential alternatives to hRBCs.

Auxiliary liver xenotransplantation technique in a transgenic pig-to-non-human primate model: A surgical approach to prolong survival.

Xenotransplantation using pigs' liver offers a potentially alternative method to overcome worldwide donor shortage, or more importantly as a bridge to allotransplantation. However, it has been challenged by profound thrombocytopenia and fatal coagulopathy in non-human primate models. Here we suggest that a left auxiliary technique can be a useful method to achieve extended survival of the xenograft. Fifteen consecutive liver xenotransplants were carried out in a pig-to-cynomolgus model. Right auxiliary technique was implemented in two cases, orthotopic in eight cases, and left auxiliary in five cases. None of the right auxiliary recipients survived after surgery due to hemorrhage during complex dissection between the primate's right lobe and inferior vena cava. Orthotopic recipients survived less than 7 days secondary to profound thrombocytopenia and coagulopathy. Two out of five left auxiliary xenotransplants survived more than 3 weeks without uncontrolled thrombocytopenia or anemia, with one of them surviving 34 days, the longest graft survival reported to date. Left auxiliary xenotransplant is a feasible approach in non-human primate experiments, and the feared risk of thrombocytopenia and coagulopathy can be minimized. This may allow for longer evaluation of the xenograft and help better understand histopathological and immunological changes that occur following liver xenotransplantation.

Effects of extracellular vesicles derived from steroids-primed oviductal epithelial cells on porcine in vitro embryonic development.

Extracellular vesicles (EVs) play an active role in regulating different physiological events, however, endocrine control of EVs cargo contents remain poorly understood. In this study, we aimed to isolate EVs from the porcine oviductal epithelial cells (POECs) that were primed with steroid hormones including estradiol (E2) and progesterone (P4), mimicking the in vivo conditions of the reproductive cycle and studied their effects on in vitro produced embryonic development. For this purpose, POECs were treated either with 0 concentration (control) or two different combinations of E2 and P4 including 50 pg/mL E2 + 0.5 ng/mL P4 (group H1), and 10 pg/mL E2 + 35 ng/mL P4 (group H2). Embryos were prepared after in vitro maturation either by parthenogenetic activation or somatic cell nuclear transfer (SCNT) technique. Treating parthenogenetic embryo with EVs, led a significantly higher rate of the blastocyst formation in the group supplemented with each EVs, compared to the control group. In addition, TUNEL assay and gene expression level analysis revealed that apoptosis was significantly reduced in the H2 EVs group. Furthermore, EVs from hormone-primed POECs improved the formation rate of porcine SCNT embryos compared to the control group. While in each EVs supplemented group (control EVs, H1 EVs, H2 EVs), the expression of cell reprogramming-related genes in cloned embryos showed a tendency of increase, the effect was stronger in H1 EVs and H2 EVs. In conclusion, EVs derived from POECs cultured in hormonal conditions simulating the in vivo environment had a positive effect on porcine blastocysts formation, which will likely facilitate in the production of cloned embryos.

The combination of rolipram and cilostamide improved the developmental competence of cloned porcine embryos.

In vitro maturation of porcine oocytes is characterized by asynchronous cytoplasmic and nuclear maturation, leading to less competent oocytes supporting embryo development. The purpose of this study was to evaluate the combined effect of rolipram and cilostamide as cyclic Adenine monophosphate (cAMP) modulators to find the maximum cAMP levels that temporarily arrest meiosis. We determined the optimal time to maintain functional gap junction communication during pre-in vitro maturation to be four hours. Oocyte competence was evaluated by the level of glutathione, reactive oxygen species, meiotic progression, and gene expression. We evaluated embryonic developmental competence after parthenogenetic activation and somatic cell nuclear transfer. The combined treatment group showed significantly higher glutathione and lower reactive oxygen species levels and a higher maturation rate than the control and single treatment groups. Cleavage and blastocyst formation rates in parthenogenetic activation and somatic cell nuclear transfer embryos were higher in two-phase in vitro maturation than in the other groups. The relative levels of BMP15and GDF9 expression were increased in two-phase in vitro maturation. Somatic cell nuclear transfer blastocysts from two-phase in vitro maturation oocytes showed a lower level of expression of apoptotic genes than the control, indicating better pre-implantation developmental competence. The combination of rolipram and cilostamide resulted in optimal synchrony of cytoplasmic and nuclear maturation in porcine in vitro matured oocytes and there by enhanced the developmental competence of pre-implantation embryos.

A desirable transgenic strategy using GGTA1 endogenous promoter-mediated knock-in for xenotransplantation model.

Pig-to-human organ transplantation is a feasible solution to resolve the shortage of organ donors for patients that wait for transplantation. To overcome immunological rejection, which is the main hurdle in pig-to-human xenotransplantation, various engineered transgenic pigs have been developed. Ablation of xeno-reactive antigens, especially the 1,3-Gal epitope (GalT), which causes hyperacute rejection, and insertion of complement regulatory protein genes, such as hCD46, hCD55, and hCD59, and genes to regulate the coagulation pathway or immune cell-mediated rejection may be required for an ideal xenotransplantation model. However, the technique for stable and efficient expression of multi-transgenes has not yet been settled to develop a suitable xenotransplantation model. To develop a stable and efficient transgenic system, we knocked-in internal ribosome entry sites (IRES)-mediated transgenes into the α 1,3-galactosyltransferase (GGTA1) locus so that expression of these transgenes would be controlled by the GGTA1 endogenous promoter. We constructed an IRES-based polycistronic hCD55/hCD39 knock-in vector to target exon4 of the GGTA1 gene. The hCD55/hCD39 knock-in vector and CRISPR/Cas9 to target exon4 of the GGTA1 gene were co-transfected into white yucatan miniature pig fibroblasts. After transfection, hCD39 expressed cells were sorted by FACS. Targeted colonies were verified using targeting PCR and FACS analysis, and used as donors for somatic cell nuclear transfer. Expression of GalT, hCD55, and hCD39 was analyzed by FACS and western blotting. Human complement-mediated cytotoxicity and human antibody binding assays were conducted on peripheral blood mononuclear cells (PBMCs) and red blood cells (RBCs), and deposition of C3 by incubation with human complement serum and platelet aggregation were analyzed in GGTA1 knock-out (GTKO)/CD55/CD39 pig cells. We obtained six targeted colonies with high efficiency of targeting (42.8% of efficiency). Selected colony and transgenic pigs showed abundant expression of targeted genes (hCD55 and hCD39). Knocked-in transgenes were expressed in various cell types under the control of the GGTA1 endogenous promoter in GTKO/CD55/CD39 pig and IRES was sufficient to express downstream expression of the transgene. Human IgG and IgM binding decreased in GTKO/CD55/CD39 pig and GTKO compared to wild-type pig PBMCs and RBCs. The human complement-mediated cytotoxicity of RBCs and PBMCs decreased in GTKO/CD55/CD39 pig compared to cells from GTKO pig. C3 was also deposited less in GTKO/CD55/CD39 pig cells than wild-type pig cells. The platelet aggregation was delayed by hCD39 expression in GTKO/CD55/CD39 pig. In the current study, knock-in into the GGTA1 locus and GGTA1 endogenous promoter-mediated expression of transgenes are an appropriable strategy for effective and stable expression of multi-transgenes. The IRES-based polycistronic transgene vector system also caused sufficient expression of both hCD55 and hCD39. Furthermore, co-transfection of CRISPR/Cas9 and the knock-in vector not only increased the knock-in efficiency but also induced null for GalT by CRISPR/Cas9-mediated double-stranded break of the target site. As shown in human complement-mediated lysis and human antibody binding to GTKO/CD55/CD39 transgenic pig cells, expression of hCD55 and hCD39 with ablation of GalT prevents an effective immunological reaction in vitro. As a consequence, our technique to produce multi-transgenic pigs could improve the development of a suitable xenotransplantation model, and the GTKO/CD55/CD39 pig developed could prolong the survival of pig-to-primate xenotransplant recipients.

Effect of Factor H on Complement Alternative Pathway Activation in Human Serum Remains on Porcine Cells Lacking N-Glycolylneuraminic Acid.

Background: Triple knockout (TKO) donor pigs lacking alpha-1,3-galactose (Gal), N-glycolylneuraminic acid (Neu5Gc), and Sd(a) expressions were developed to improve the clinical success of xenotransplantation. Neu5Gc, a sialic acid expressed on cell surfaces, recruits factor H to protect cells from attack by the complement system. Lack of Neu5Gc expression may cause unwanted complement activation, abrogating the potential benefit of gene-modified donor pigs. To investigate whether TKO porcine cells display increased susceptibility to complement activation in human serum, pathway-specific complement activation, apoptosis, and human platelet aggregation by porcine cells were compared between alpha-1,3-galactosyltransferase gene-knockout (GTKO) and TKO porcine cells. Methods: Primary porcine peripheral blood mononuclear cells (pPBMCs) and endothelial cells (pECs) from GTKO and TKO pigs were used. Cells were incubated in human serum diluted in gelatin veronal buffer (GVB++) or Mg++-EGTA GVB, and C3 deposition and apoptotic changes in these cells were measured by flow cytometry. C3 deposition levels were also measured after incubating these cells in 10% human serum supplemented with human factor H. Platelet aggregation in human platelet-rich plasma containing GTKO or TKO pECs was analyzed. Results: The C3 deposition level in GTKO pPBMCs or pECs in GVB++ was significantly higher than that of TKO pPBMCs or pECs, respectively, but C3 deposition levels in Mg++-EGTA-GVB were comparable between them. The addition of factor H into the porcine cell suspension in 10% serum in Mg++ -EGTA-GVB inhibited C3 deposition in a dose-dependent manner, and the extent of inhibition by factor H was similar between GTKO and TKO porcine cells. The percentage of late apoptotic cells in porcine cell suspension in GVB++ increased with the addition of human serum, of which the net increase was significantly less in TKO pPBMCs than in GTKO pPBMCs. Finally, the lag time of platelet aggregation in recalcified human plasma was significantly prolonged in the presence of TKO pECs compared to that in the presence of GTKO pECs. Conclusion: TKO genetic modification protects porcine cells from serum-induced complement activation and apoptotic changes, and delays recalcification-induced human platelet aggregation. It does not hamper factor H recruitment on cell surfaces, allowing the suppression of alternative complement pathway activation.

Vitamin C enhances porcine cloned embryo development and improves the derivation of embryonic stem-like cells.

Porcine cloning through somatic cell nuclear transfer (SCNT) has been widely used in biotechnology for generating animal disease models and genetically modified animals for xenotransplantation. Vitamin C is a multifunctional factor that reacts with several enzymes. In this study, we used porcine oocytes to investigate the effects of different concentrations of vitamin C on in vitro maturation (IVM), in vitro culture (IVC), and the derivation of nuclear transfer embryonic stem-like cells (NT-ESCs). We demonstrated that vitamin C promoted the cleavage and blastocyst rate of genetically modified cloned porcine embryos and improved the derivation of NT-ESCs. Vitamin C integrated into IVM and IVC enhanced cleavage and blastocyst formation (P < 0.05) in SCNT embryos. Glutathione level was increased, and reactive oxygen species levels were decreased (P < 0.05) due to vitamin C treatment. Vitamin C decreased the gene expression of apoptosis (BAX) and increased the expression of genes associated with nuclear reprogramming (NANOG, POU5F1, SOX2, c-Myc, Klf4, and TEAD4), antioxidation (SOD1), anti-apoptotic (Bcl2), and trophectoderm (CDX2). Moreover, vitamin C improved the attachment, derivation, and passaging of NT-ESCs, while the control group showed no outgrowths beyond the primary culture. In conclusion, supplementation of vitamin C at a dose of 50 µg/ml to the IVM and IVC culture media was appropriate to improve the outcomes of porcine IVM and IVC and for the derivation of NT-ESCs as a model to study the pre- and post-implantation embryonic development in cloned transgenic embryos. Therefore, we recommend the inclusion of vitamin C as a supplementary factor to IVM and IVC to improve porcine in vitro embryonic development.

Human immune reactivity of GGTA1/CMAH/A3GALT2 triple knockout Yucatan miniature pigs.

In this study, we investigated the effect of a triple knockout of the genes alpha-1,3-galactosyltransferase (GGTA1), cytidine monophosphate-N-acetylneuraminic acid hydroxylase (CMAH), and alpha 1,3-galactosyltransferase 2 (A3GALT2) in Yucatan miniature pigs on human immune reactivity. We used the CRISPR/Cas9 system to create pigs lacking GGTA1 (GTKO) and GGTA1/CMAH/A3GALT2 triple gene knockout (TKO). The expression of all three xenoantigens was absent in TKO pigs, but there was no additional reduction in the level of Galα1,3Gal (αGal) epitopes expression in the A3GALT2 gene KO. Peripheral blood mononuclear cells (PBMCs), aorta endothelial cells (AECs), and cornea endothelial cells (CECs) were isolated from these pigs, and their ability to bind human IgM/IgG and their cytotoxicity in human sera were evaluated. Compared to wild type (WT) pigs, the level of human antibody binding of the PBMCs, AECs, and CECs of the transgenic pigs (GTKO and TKO) was significantly reduced. However, there were significant differences in human antibody binding between GTKO and TKO depending on the cell type. Human antibody binding of TKO pigs was less than that of GTKO on PBMCs but was similar between GTKO and TKO pigs for AECs and CECs. Cytotoxicity of transgenic pig (GTKO and TKO) PBMCs and AECs was significantly reduced compared to that of WT pigs. However, TKO pigs showed a reduction in cytotoxicity compared to GTKO pigs on PBMCs, whereas in AECs from both TKO and GTKO pigs, there was no difference. The cytotoxicity of transgenic pig CECs was significantly decreased from that of WT at 300 min, but there was no significant reduction in TKO pigs from GTKO. Our results indicate that genetic modification of donor pigs for xenotransplantation should be tailored to the target organ and silencing of additional genes such as CMAH or A3GALT2 based on GTKO might not be essential in Yucatan miniature pigs.

Comparison of islet isolation result and clinical applicability according to GMP-grade collagenase enzyme blend in adult porcine islet isolation and culture.

BACKGROUND: Porcine islet xenotransplantation is a promising treatment for type 1 diabetes as an alternative to human pancreatic islet transplantation and long-term insulin therapy. Several research groups have explored porcine islets as an alternative to the inconsistent and chronic shortage of pancreases from human organ donors. Studies have confirmed successful transplant of porcine islets into non-human primate models of diabetes; however, in most cases, they require more than one adult porcine donor to achieve sufficient viable islet mass for sustained function. The importance of GMP-grade reagents includes the following: specific enzymes utilized in the pancreatic isolation process were identified as a key factor in successful human clinical islet transplantation trials using cadaveric islets. As xenotransplantation clinical research progresses, isolation reagents and digestion enzymes play a key role in the consistency of the product and ultimately the outcome of the islet xenotransplant. In this study, we evaluated several commercially available enzyme blends that have been used for islet isolation. We evaluated their impact on islet isolation yield and subsequent islet function as part of our plan to bring xenotransplantation into clinical xenotransplantation trials. METHODS: Adult porcine islets were isolated from 16 to 17-month-old Yucatan miniature pigs following standard rapid procurement. Pigs weighed on average 48.71 ± 2.85 kg, and the produced pancreases were 39.51 ± 1.80 grams (mean ± SEM). After ductal cannulation, we evaluated both GMP-grade enzymes (Collagenase AF-1 GMP grade and Liberase MTF C/T GMP grade) and compared with standard non-GMP enzyme blend (Collagenase P). Islet quality control assessments including islet yield, islet size (IEQ), membrane integrity (acridine orange/propidium iodide), and functional viability (GSIS) were evaluated in triplicate on day 1 post-islet isolation culture. RESULTS: Islet yield was highest in the group of adult pigs where Collagenase AF-1 GMP grade was utilized. The mean islet yield was 16 586 ± 1391 IEQ/g vs 8302 ± 986 IEQ/g from pancreases isolated using unpurified crude Collagenase P. The mean islet size was higher in Collagenase AF-1 GMP grade with neutral protease than in Collagenase P and Liberase MTF C/T GMP grade. We observed no significant difference between the experimental groups, but in vitro islet function after overnight tissue culture was significantly higher in Collagenase AF-1 GMP grade with neutral protease and Liberase MTF C/T GMP grade than the crude control enzyme group. As expected, the GMP-grade enzyme has significantly lower endotoxin levels than the crude control enzyme group when measured. CONCLUSIONS: This study validates the importance of using specifically blended GMP grade for adult pig islet isolation for xenotransplantation trials and the ability to isolate a sufficient number of viable islets from one adult pig to provide a sufficient number for islets for a clinical islet transplantation. GMP-grade enzymes are highly efficient in increasing islet yield, size, viability, and function at a lower and acceptable endotoxin level. Ongoing research transplants these islets into animal models of diabetes to validate in vivo function. Also, these defined and reproducible techniques using GMP-grade enzymes allow for continuance of our plan to advance to xenotransplantation of isolated pig islets for the treatment of type 1 diabetes.

Screening of Integrin Heterodimers Expressed Functionally on the Undifferentiated Spermatogonial Stem Cells in the Outbred ICR Mice.

BACKGROUND AND OBJECTIVES: Outbred mice are widely used in toxicology, pharmacology, and fundamental biomedical research. However, there have been no reports of in vitro culture systems for spermatogonial stem cells (SSCs) derived from these mice. METHODS: As a step towards constructing a non-cellular niche supporting the in vitro maintenance of outbred mouse SSC self-renewal, we systematically investigated the types of integrin heterodimers that are expressed transcriptionally, translationally, and functionally in SSCs derived from Imprinting Control Region (ICR) mice. RESULTS: Among the genes encoding 25 integrin subunits, integrin α1, α5, α6, α9, αV, and αE, and integrin ß1 and ß5 had significantly higher transcriptional levels than the other subunits. Furthermore, at the translational level, integrin α5, α6, α9, αV, αE, and ß1 were localized on the surface of SSCs, but integrin α1 and ß5 not. Moreover, significantly stronger translational expression than integrin α9 and αE was observed in integrin α5, α6, αV, and ß1. SSCs showed significantly increased adhesion to fibronectin, laminin, tenascin C and vitronectin, and functional blocking of integrin α5ß1, α6ß1, α9ß1 or αVß1 significantly inhibited adhesion to these molecules. CONCLUSIONS: We confirmed that integrin α5ß1, α6ß1, α9ß1 and αVß1 actively function on the surface of undifferentiated SSCs derived from outbred ICR mice.

Long-term survival of full-thickness corneal xenografts from α1,3-galactosyltransferase gene-knockout miniature pigs in non-human primates.

BACKGROUND: We aimed to investigate (a) the long-term survival of corneal grafts from α1,3-galactosyltransferase gene-knockout miniature (GTKOm) pigs in non-human primates as a primary outcome and (b) the effect of anti-CD20 antibody on the survival of corneal grafts from GTKOm pigs as a secondary outcome. METHODS: Nine rhesus macaques undergoing full-thickness corneal xenotransplantation using GTKOm pigs were systemically administered steroid, basiliximab, intravenous immunoglobulin, and tacrolimus with (CD20 group) or without (control group) anti-CD20 antibody. RESULTS: Graft survival was significantly longer (P = .008) in the CD20 group (>375, >187, >187, >83 days) than control group (165, 91, 72, 55, 37 days). When we compared the graft survival time between older (>7- month-old) and younger (≤7-month-old) aged donor recipients, there was no significant difference. Activated B cells were lower in the CD20 group than control group (P = .026). Aqueous humor complement C3a was increased in the control group at last examination (P = .043) and was higher than that in the CD20 group (P = .014). Anti-αGal IgG/M levels were unchanged in both groups. At last examination, anti-non-Gal IgG was increased in the control group alone (P = .013). CONCLUSIONS: The GTKOm pig corneal graft achieved long-term survival when combined with anti-CD20 antibody treatment. Inhibition of activated B cells and complement is imperative even when using GTKO pig corneas.

No excessive mutations in transcription activator-like effector nuclease-mediated α-1,3-galactosyltransferase knockout Yucatan miniature pigs.

OBJECTIVE: Specific genomic sites can be recognized and permanently modified by genome editing. The discovery of endonucleases has advanced genome editing in pigs, attenuating xenograft rejection and cross-species disease transmission. However, off-target mutagenesis caused by these nucleases is a major barrier to putative clinical applications. Furthermore, off-target mutagenesis by genome editing has not yet been addressed in pigs. METHODS: Here, we generated genetically inheritable α-1,3-galactosyltransferase (GGTA1) knockout Yucatan miniature pigs by combining transcription activator-like effector nuclease (TALEN) and nuclear transfer. For precise estimation of genomic mutations induced by TALEN in GGTA1 knockout pigs, we obtained the whole-genome sequence of the donor cells for use as an internal control genome. RESULTS: In-depth whole-genome sequencing analysis demonstrated that TALEN-mediated GGTA1 knockout pigs had a comparable mutation rate to homologous recombination-treated pigs and wild-type strain controls. RNA sequencing analysis associated with genomic mutations revealed that TALEN-induced off-target mutations had no discernable effect on RNA transcript abundance. CONCLUSION: Therefore, TALEN appears to be a precise and safe tool for generating genome-edited pigs, and the TALEN-mediated GGTA1 knockout Yucatan miniature pigs produced in this study can serve as a safe and effective organ and tissue resource for clinical applications.

Fabrication of a Novel Absorbable Vascular Anastomosis Device and Testing in a Pig Liver Transplantation Model.

An absorbable vascular anastomosis device (AVAD) was fabricated and tested in pig liver transplantation experiments. We prepared biodegradable copolymers with various ratios of L-lactide: glycolide and tested their properties including inherent viscosity, in vitro biodegradation, and tensile strength. The mechanical and physical properties of the finally selected copolymers were analyzed according to decomposition time. The AVAD, consisting of two inner rings and one coupler, was fabricated with 5-, 15-, and 20-mm diameter sizes using an injection molding machine. Based on changes in the overall mechanical and physical properties, it is believed that the AVAD will maintain its shape without deformation while connecting the blood vessels to external force for at least 3 weeks. Four mini-pigs underwent liver transplantation with AVAD using livers obtained from swine leukocyte antigen-identical siblings. Anastomoses was achieved in all four cases. In case 4, an autopsy conducted at 4 months revealed that the AVAD was absorbed and the anastomosis was intact, demonstrating the success of the AVAD in the pig liver transplantation experiments and the feasibility of using an AVAD in organ transplantation.

Effect of alanine supplementation during in vitro maturation on oocyte maturation and embryonic development after parthenogenesis and somatic cell nuclear transfer in pigs.

The objective of this study was to examine the effect of alanine treatment during in vitro maturation (IVM) on oocyte maturation and embryonic development in pigs. To this end, we investigated the nuclear maturation, intraoocyte glutathione (GSH) content of IVM oocytes, and embryonic development after parthenogenesis (PA) and somatic cell nuclear transfer (SCNT). In addition, we analyzed the expression of genes associated with apoptosis and embryonic development in IVM oocytes, 4-cell stage embryos, and blastocysts produced via PA and SCNT. To determine the optimal concentration of alanine to promote the maturation and development of PA and SCNT embryos, various concentrations (0, 0.363, 1, 5, and 10 mM) of alanine were added to IVM medium during oocyte maturation. The proportion of metaphase II (MII) oocytes after IVM did not differ according to the concentration of alanine. However, significantly higher intraoocyte GSH content was observed in oocytes treated with 0.363 mM alanine compared with that in untreated oocytes. However, treatment of recipient oocytes with 5 or 10 mM alanine during IVM decreased the GSH content in mature oocytes compared to that in control oocytes. Oocytes matured in the presence of 0.363 mM alanine showed significantly increased rates of cleavage and blastocyst formation after PA and SCNT compared to untreated oocytes. PA and SCNT embryos from the 0.363 mM alanine-treated group of MII oocytes showed significantly higher transcript levels of POU5F1 and FGFR2, which are associated with oocyte quality and embryonic development, than the untreated group. Our results suggest that treatment of pig oocytes with 0.363 mM alanine during IVM improves embryonic developmental competence after PA and SCNT by increasing intraoocyte GSH content and increasing the mRNA expression of POU5F1 and FGFR2.

Production of heterozygous alpha 1,3-galactosyltransferase (GGTA1) knock-out transgenic miniature pigs expressing human CD39.

Production of transgenic pigs for use as xenotransplant donors is a solution to the severe shortage of human organs for transplantation. The first barrier to successful xenotransplantation is hyperacute rejection, a rapid, massive humoral immune response directed against the pig carbohydrate GGTA1 epitope. Platelet activation, adherence, and clumping, all major features of thrombotic microangiopathy, are inevitable results of immune-mediated transplant rejection. Human CD39 rapidly hydrolyzes ATP and ADP to AMP; AMP is hydrolyzed by ecto-5'-nucleotidase (CD73) to adenosine, an anti-thrombotic and cardiovascular protective mediator. In this study, we developed a vector-based strategy for ablation of GGTA1 function and concurrent expression of human CD39 (hCD39). An hCD39 expression cassette was constructed to target exon 4 of GGTA1. We established heterozygous GGTA1 knock-out cell lines expressing hCD39 from pig ear fibroblasts for somatic cell nuclear transfer (SCNT). We also described production of heterozygous GGTA1 knock-out piglets expressing hCD39 and analyzed expression and function of the transgene. Human CD39 was expressed in heart, kidney and aorta. Human CD39 knock-in heterozygous ear fibroblast from transgenic cloned pigs, but not in non-transgenic pig's cells. Expression of GGTA1 gene was lower in the knock-in heterozygous ear fibroblast from transgenic pigs compared to the non-transgenic pig's cell. The peripheral blood mononuclear cells (PBMC) from the transgenic pigs were more resistant to lysis by pooled complement-preserved normal human serum than that from wild type (WT) pig. Accordingly, GGTA1 mutated piglets expressing hCD39 will provide a new organ source for xenotransplantation research.

Analysis of Swine Leukocyte Antigen Haplotypes in Yucatan Miniature Pigs Used as Biomedical Model Animal.

The porcine major histocompatibility complex (MHC) is called swine leukocyte antigen (SLA), which controls immune responses and transplantation reactions. The SLA is mapped on pig chromosome 7 (SSC7) near the centromere. In this study, 3 class I (SLA-1, SLA-3, and SLA-2) and 3 class II (DRB1, DQB1, and DQA) genes were used for investigation of SLA haplotypes in Yucatan miniature pigs in Korea. This pig breed is a well-known model organism for biomedical research worldwide. The current study indicated that Korean Yucatan pig population had 3 Class I haplotypes (Lr-4.0, Lr-6.0, and Lr-25.0) and 3 class II haplotypes (Lr-0.5, Lr-0.7, and Lr-0.25). The combinations of SLA class I and II haplotype together, 2 homozygous (Lr-4.5/4.5 and Lr-6.7/6.7) and 3 heterozygous (Lr-4.5/6.7, Lr-4.5/25.25, and Lr-6.7/25.25) haplotypes were identified, including previously unidentified new heterozygous haplotypes (Lr-4.5/4.7). In addition, a new SLA allele typing method using Agilent 2100 bioanalyzer was developed that permitted more rapid identification of SLA haplotypes. These results will facilitate the breeding of SLA homozygous Yucatan pigs and will expedite the possible use of these pigs for the biomedical research, especially xenotransplantation research.