Blood groups and transfusions in pigs

Histo-Blood Group Antigen-Producing Bacterial Cocktail Reduces Rotavirus A, B, and C Infection and Disease in Gnotobiotic Piglets

The suboptimal performance of rotavirus (RV) vaccines in developing countries and in animals necessitates further research on the development of novel therapeutics and control strategies. To initiate infection, RV interacts with cell-surface O-glycans, including histo-blood group antigens (HBGAs). We have previously demonstrated that certain non-pathogenic bacteria express HBGA- like substances (HBGA+) capable of binding RV particles in vitro. We hypothesized that HBGA+ bacteria can bind RV particles in the gut lumen protecting against RV species A (RVA), B (RVB), and C (RVC) infection in vivo. In this study, germ-free piglets were colonized with HBGA+ or HBGA- bacterial cocktail and infected with RVA/RVB/RVC of different genotypes. Diarrhea severity, virus shedding, immunoglobulin A (IgA) Ab titers, and cytokine levels were evaluated. Overall, colonization with HBGA+ bacteria resulted in reduced diarrhea severity and virus shedding compared to the HBGA- bacteria. Consistent with our hypothesis, the reduced severity of RV disease and infection was not associated with significant alterations in immune responses. Additionally, colonization with HBGA+ bacteria conferred beneficial effects irrespective of the piglet HBGA phenotype. These findings are the first experimental evidence that probiotic performance in vivo can be improved by including HBGA+ bacteria, providing decoy epitopes for broader/more consistent protection against diverse RVs.

Validation of the slaughterhouse porcine heart model for ex-situ heart perfusion studies

INTRODUCTION

To validate slaughterhouse hearts for ex-situ heart perfusion studies, we compared cold oxygenated machine perfusion in less expensive porcine slaughterhouse hearts (N = 7) to porcine hearts that are harvested following the golden standard in laboratory animals (N = 6).

METHODS

All hearts received modified St Thomas 2 crystalloid cardioplegia prior to 4 hours of cold oxygenated machine perfusion. Hearts were perfused with homemade modified Steen heart solution with a perfusion pressure of 20-25 mmHg to achieve a coronary flow between 100-200 mL/min. Reperfusion and testing was performed for 4 hours on a normothermic, oxygenated diluted whole blood loaded heart model. Survival was defined by a cardiac output above 3 L with a mean aortic pressure above 60 mmHg.

RESULTS

Both groups showed 100% functional survival, with laboratory hearts displaying superior cardiac function. Both groups showed similar decline in function over time.

CONCLUSION

We conclude that the slaughterhouse heart can be used as an alternative to laboratory hearts and provides a cost-effective method for future ex-situ heart perfusion studies.

Genetic diversity, growth and heart function of Auckland Island pigs, a potential source for organ xenotransplantation

One of the prerequisites for successful organ xenotransplantation is a reasonable size match between the porcine organ and the recipient's organ to be replaced. Therefore, the selection of a suitable genetic background of source pigs is important. In this study, we investigated body and organ growth, cardiac function, and genetic diversity of a colony of Auckland Island pigs established at the Center for Innovative Medical Models (CiMM), LMU Munich. Male and female Auckland Island pig kidney cells (selected to be free of porcine endogenous retrovirus C) were imported from New Zealand, and founder animals were established by somatic cell nuclear transfer (SCNT). Morphologically, Auckland Island pigs have smaller body stature compared to many domestic pig breeds, rendering their organ dimensions well-suited for human transplantation. Furthermore, echocardiography assessments of Auckland Island pig hearts indicated normal structure and functioning across various age groups throughout the study. Single nucleotide polymorphism (SNP) analysis revealed higher runs of homozygosity (ROH) in Auckland Island pigs compared to other domestic pig breeds and demonstrated that the entire locus coding the swine leukocyte antigens (SLAs) was homozygous. Based on these findings, Auckland Island pigs represent a promising genetic background for organ xenotransplantation.

Comparison of different porcine models simulating myocardial cold ischemia of pediatric donor hearts

BACKGROUND

Our team previously identified a stem cell-derived cardioprotective additive that can be added to standard cardioplegia to extend myocardial viability during prolonged myocardial cold ischemic time (CIT) in rodent models. The purpose of this study was to utilize a porcine model to compare in-vivo versus ex-vivo porcine simulation of CIT that accompanies cardiac transplantation in humans, in order to determine an optimal method for translation of our studies to larger animals.

METHODS

Eight 39-55 kg Yorkshire X pigs were randomly assigned to either in-vivo or ex-vivo simulation. After administration of general anesthesia and endotracheal intubation, baseline measurement of left ventricular performance was obtained via transesophageal echocardiography (TEE). After midline sternotomy and heparin administration, the aorta was cross-clamped and two liters of HTK-Custodiol were introduced via the aortic root. The in-vivo method utilized cold ischemic heart storage in the chest cavity while supporting the experimental animal with cardiopulmonary bypass (CPB). The ex-vivo method involved standard cardiac procurement, cold ischemic storage outside of the body, and subsequent cardiac reperfusion utilizing cardiac reanimation in a Langendorff heart perfusion mode. After CIT, measurements of post-ischemic left ventricular performance were obtained via echocardiography. Results are presented as: Mean ± Standard Deviation (Median, Minimum-Maximum).

RESULTS

Weight (kilograms) was similar in the in-vivo group and the ex-vivo group: 44 ± 1.8 (44, 42-46) versus 44 ± 5.1 (43.5, 39-51), respectively. Cold ischemic time (minutes) was longer in the ex-vivo group: 360 ± 0 (360, 360-360) versus 141 ± 26.7 (149, 102-163). Temperature (degrees Celsius) was colder in the ex-vivo group: 8 ± 0 (8, 8-8) versus 16.5 ± 4.2 (16, 12-16).In the in-vivo group, baseline ejection fraction and ejection fraction after CIT were: 48.25% ± 14.95% (48.5%, 33%-63%) and 41.25% ± 22.32% (41.5%, 20%-62%), respectively. In the ex-vivo group, baseline ejection fraction and ejection fraction after CIT were: 56.4% ± 5.9% (57%, 50%-67%) and 60.4% ± 7.7% (61.5%, 51.9%-67%), respectively.

CONCLUSION

The ex-vivo technique is suitable to evaluate cardioplegia additives that may substantially extend myocardial tolerance to cold ischemia.

Validation of a human paper-based blood typing method for use in pet pigs

BACKGROUND

Evidence-based medical practices for pet pigs are needed. EldonCard is a human blood-typing card shown to be rapid and reliable in identifying blood phenotypes of pet pigs. The objective of this study was to validate EldonCard by determining its reliability, reproducibility, and robustness for its routine use in the clinical setting.

KEY FINDINGS

Twenty-four venous blood samples from pet pigs were collected for a prospective in vitro study. Blood genotypes ("EAAA0 " and "EAA00 ") were identified in 15 samples via polymerase chain reaction (PCR). All samples were phenotyped ("A," "Aweak ," and "0" or "-") via EldonCard. Kappa (κ) statistics measured the level of agreement between 2 raters, and between EldonCard and PCR. McNemar's test determined if an association between the blood types and EldonCard or PCR exists, with significance at P < 0.05. Agreement between raters and methods was perfect (60/60 [100%], κ:1, P < 0.001; 15/15 [100%], κ:1, P < 0.001). There was no difference in the proportions of blood groups based on method.

SIGNIFICANCE

In conjunction with previous data, EldonCard is a rapid, accurate, reliable, precise, and robust in-clinic blood-typing method for the A0 system of pet pigs. EldonCard is now a validated blood-typing tool for the A0 system of pet pigs and maybe used for pretransfusion screenings and identification of donors and recipients.

Prevalence of AO blood group and level of agreement for AO blood-typing methods in pet pigs from Louisiana

OBJECTIVES

Pet pigs are a species of growing medical interest, and evidence-based practices for blood transfusions are needed. The objectives of this study were to quantify the prevalence of 3 blood group (Bg) phenotypes ("A" and "Aweak " resulting from EAAAA and EAAAO , "0" from EAA00 , or "-" from EAA00 or SSS alleles) in pet pigs and compare results using a human blood-typing card (EldonCard), standard saline agglutination (SSA), and polymerase chain reaction (PCR) sequencing.

DESIGN

Cross-sectional study.

SETTING

University veterinary teaching hospital.

ANIMALS

Ninety-seven pet pigs from Louisiana.

INTERVENTIONS

Blood was sampled from randomly selected pet pigs of various breeds, anticoagulated with EDTA, and typed using each investigated test according to the manufacturers' directions or standard laboratory technique. Samples for PCR analysis were stored at -80°C until analysis. Phenotypes were screened via EldonCard. Association between Bg and sex was investigated using chi-square test, with significance at P < 0.05. Kappa (κ) statistic was used to measure the level of agreement between the 3 tests.

MEASUREMENTS AND MAIN RESULTS

Pot-bellied pigs represented the majority (84.5%) of this population, with 52 (53.6%) males and 45 (46.4%) females. Genotypic frequencies were 30%, 30%, and 40% for "EAAAA ," "EAAAO ," and "EAA00 ," respectively. Based on EldonCard, 38 phenotypes were classified as "A," 5 as "Aweak ," and 54 as "0" or "-." Results were identical for Bg, with the 3 tested techniques in 90% (45/50) of samples. Agreement between EldonCard and PCR was almost perfect (49/50 [98%], κ = 0.959; P < 0.001). Agreement between SSA and PCR, and EldonCard and SSA was substantial (46/50 [92%], κ = 0.803, P < 0.001 and 93/97 [95.9%], κ = 0.764, P < 0.001, respectively).

CONCLUSIONS

The most common blood type was "0" or "-" (55.7%), followed by "A" (39.2%) and "Aweak " (5.1%). There was strong agreement between EldonCard and PCR testing. EldonCard allowed for rapid and reliable phenotype identification ("A," "Aweak ," and "0" or "-") and represents a clinically applicable laboratory method for blood typing in pet pigs.

Ex vivo enzymatic treatment converts blood type A donor lungs into universal blood type lungs

Donor organ allocation is dependent on ABO matching, restricting the opportunity for some patients to receive a life-saving transplant. The enzymes FpGalNAc deacetylase and FpGalactosaminidase, used in combination, have been described to effectively convert group A (ABO-A) red blood cells (RBCs) to group O (ABO-O). Here, we study the safety and preclinical efficacy of using these enzymes to remove A antigen (A-Ag) from human donor lungs using ex vivo lung perfusion (EVLP). First, the ability of these enzymes to remove A-Ag in organ perfusate solutions was examined on five human ABO-A1 RBC samples and three human aortae after static incubation. The enzymes removed greater than 99 and 90% A-Ag from RBCs and aortae, respectively, at concentrations as low as 1 μg/ml. Eight ABO-A1 human lungs were then treated by EVLP. Baseline analyses of A-Ag in lungs revealed expression predominantly in the endothelial and epithelial cells. EVLP of lungs with enzyme-containing perfusate removed over 97% of endothelial A-Ag within 4 hours. No treatment-related acute lung toxicity was observed. An ABO-incompatible transplant was then simulated with an ex vivo model of antibody-mediated rejection using ABO-O plasma as the surrogate for the recipient circulation using three donor lungs. The treatment of donor lungs minimized antibody binding, complement deposition, and antibody-mediated injury as compared with control lungs. These results show that depletion of donor lung A-Ag can be achieved with EVLP treatment. This strategy has the potential to expand ABO-incompatible lung transplantation and lead to improvements in fairness of organ allocation.

Initial experimental experience of triple-knockout pig red blood cells as potential sources for transfusion in alloimmunized patients with sickle cell disease

BACKGROUND

Blood transfusion remains important in the treatment of patients with sickle cell disease (SCD). However, alloimmunization after blood transfusion is associated with patient morbidity and mortality. Triple-knockout (TKO) pigs (i.e., pigs in which the three known xenoantigens to which humans have anti-pig antibodies have been deleted) may be an alternative source of RBCs for these patients because many humans have no preformed antibodies to TKO pig RBCs (pRBCs).

METHODS AND MATERIALS

In an in vitro study, plasma from alloimmunized (n = 12) or non-alloimmunized (n = 12) SCD patients was used to determine IgM/IgG binding to, and CDC of, TKO pRBCs. In an in vivo study, after an estimated 25% of blood volume was withdrawn from two capuchin monkeys, CFSE-labeled TKO pRBCs were transfused. Loss of TKO pRBCs was monitored by flow cytometry, and 7 weeks later, 25% of blood was withdrawn, and CFSE-labeled monkey RBCs were transfused.

RESULTS

The in vitro study demonstrated that plasma from neither alloimmunized nor non-alloimmunized SCD patients bound IgM/IgG to, or induced CDC of, TKO pRBCs. In the in vivo study, survival of TKO pRBCs in the two capuchin monkeys was of 5 and 7 days, respectively, whereas after allotransfusion, survival was >28 days.

CONCLUSIONS

In conclusion, (1) in the present limited study, no antibodies were detected that cross-reacted with TKO pRBCs, and (2) TKO pigs may possibly be an alternate source of RBCs in an emergency if no human RBCs are available.

En bloc procurement of porcine abdominal multiple organ block for ex situ normothermic machine perfusion: a technique for avoiding initial cold preservation

Background

Normothermic machine perfusion (NMP) is a technique that maintains organs ex situ with normal metabolism, and organ function can be better preserved. The study of multiple-organ NMP is rarely reported. Multiple organ block (MOB) is a self-perfusing system for maintaining multiple organs ex situ, and porcine MOBs have been successfully preserved for 18 to 37 h. Due to the above context, we conceived to maintain abdominal multiple organ block (AMOB) ex situ utilizing NMP technology.

Methods

AMOBs were procured from Ba-Ma miniature pigs through en bloc procurement surgery. The process of cold preservation was eliminated between the procurement and machine perfusion, and a few minutes of warm ischemia emerged. Autologous whole blood was collected during procurement surgery as a perfusate component in the beginning.

Results

The median time of procurement surgery was approximately 220 min, and the median time of warm ischemia was 300 sec. Cases 1 and 2 suffered from repeated hypotension during the procurement surgery, and case 2 exhibited hemorrhage. After improved and optimized procurement processes, the vital signs of cases 3 to 5 remained stable during procurement. In the NMP phase, the flow increased slowly in cases 1 and 2 and did not remain stable even after continuous infusion of a high-dose vasodilator. The lactic acid level rapidly increased, and the levels of ALT and AST were obviously higher than those in cases 3 to 5. In contrast, the flow rate increased smoothly in cases 3 to 5. The lactic acid level remained stable during the first 10 h of perfusion.

Conclusions

AMOB procurement from heart-beating pigs for NMP without initial cold preservation is technically feasible.

Infection of porcine small intestinal enteroids with human and pig rotavirus A strains reveals contrasting roles for histo-blood group antigens and terminal sialic acids

Rotaviruses (RVs) are a leading cause of acute viral gastroenteritis in young children and livestock worldwide. Growing evidence suggests that host cellular glycans, such as histo-blood group antigens (HBGAs) and sialic acids (SA), are recognized by the RV surface protein VP4. However, a mechanistic understanding of these interactions and their effects on RV infection and pathogenesis is lacking. Here, we established a porcine crypt-derived 3Dintestinalenteroids (PIEs) culture system which contains all intestinal epithelial cells identified in vivo and represents a unique physiologically functional model to study RV-glycan interactions in vitro. PIEs expressing different HBGAs (A+, H+, and A+/H+) were established and isolation, propagation, differentiation and RV infection conditions were optimized. Differentiated PIEs were infected with human RV (HRV) G1P[8] Wa, porcine RV (PRV) G9P[13], PRV Gottfried G4P[6] or PRV OSU G5P[7] virulent and attenuated strains and virus replication was measured by qRT-PCR. Our results indicated that virulent HRV G1P[8] Wa replicated to the highest titers in A⁺ PIEs, while a distinct trend was observed for PRV G9P[13] or G5P[7] with highest titers in H⁺ PIEs. Attenuated Wa and Gottfried strains replicated poorly in PIEs while the replication of attenuated G9P[13] and OSU strains in PIEs was relatively efficient. However, the replication of all 4 attenuate strains was less affected by the PIE HBGA phenotypes. HBGA synthesis inhibitor 2-F-Peracetyl-Fucose (2F) treatment demonstrated that HBGAs are essential for G1P[8] Wa replication; however, they may only serve as a cofactor for PRVs G9P[13] and OSU G5P[7]. Interestingly, contrasting outcomes were observed following sialidase treatment which significantly enhanced G9P[13] replication, but inhibited the growth of G5P[7]. These observations suggest that some additional receptors recognized by G9P[13] become unmasked after removal of terminal SA. Overall, our results confirm that differential HBGAs-RV and SA-RV interactions determine replication efficacy of virulent group A RVs in PIEs. Consequently, targeting individual glycans for development of therapeutics may not yield uniform results for various RV strains.

Cell surface glycans, including histo-blood group antigens (HBGA) and sialic acids (SAs), have been shown to serve as receptors/attachment factors for many pathogens including RVs. However, how those glycans affect RV replication remains largely unknown due the lack of reliable in vitro models. To solve this problem, we established a 3D porcine intestinal enteroid (PIE) model that recapitulates the complex intestinal morphology better than conventional cell lines. By utilizing PIEs expressing different types of HBGAs, we found that several RV strains including Wa G1P[8], OSU G5P[7] and G9P[13] show preference for certain HBGA types. Interestingly, only Wa replication was reduced when HBGAs synthesis was inhibited, while that of OSU and G9P[13] was only marginally affected, which indicates that they may utilize alternative attachment factors for infection. Sialidase treatment strongly inhibited the growth of OSU, while G9P[13] replication was significantly enhanced. These findings suggest that SAs play contrasting roles in the infection of PRV OSU and G9P[13] strains. Overall, our studies demonstrate that PIEs can serve as a model to study pathogen-glycan interactions and suggest that genetically distinct RVs have evolved diverse mechanisms of cell attachment and/or entry.

Improved Normothermic Machine Perfusion After Short Oxygenated Hypothermic Machine Perfusion of Ischemically Injured Porcine Kidneys

Supplemental Digital Content is available in the text.

Background.

In an era where global kidney shortage has pushed the field of transplantation towards using more marginal donors, modified kidney preservation techniques are currently being reviewed. Some techniques require further optimization before implementation in full scale transplantation studies. Using a porcine donation after circulatory death kidney model, we investigated whether initial kidney hemodynamics improved during normothermic machine perfusion if this was preceded by a short period of oxygenated hypothermic machine perfusion (oxHMP) rather than static cold storage (SCS).

Methods.

Kidneys subjected to 75 minutes of warm ischemia were randomly assigned to either SCS (n = 4) or SCS + oxHMP (n = 4), with a total cold storage time of 240 minutes. Cold preservation was followed by 120 minutes of normothermic machine perfusion with continuous measurement of hemodynamic parameters and renal function.

Results.

oxHMP preserved kidneys maintained significantly lower renal resistance throughout the normothermic machine perfusion period compared to SCS kidneys (P < 0.001), reaching lowest levels at 60 minutes with means of 0.71 ± 0.35 mm Hg/mL/min/100 g (SCS) and 0.45 ± 0.15 mm Hg/mL/min/100 g (oxHMP). Accordingly, the oxHMP group had a higher mean renal blood flow versus SCS kidneys (P < 0.001). oxHMP kidneys had higher oxygen consumption during normothermic machine perfusion compared to SCS preserved kidneys (P < 0.001). Creatinine clearance remained similar between groups (P = 0.665).

Conclusions.

Preceding oxHMP significantly improved initial normothermic machine perfusion hemodynamics and increased total oxygen consumption. With the long period of warm ischemia, immediate kidney function was not observed, reflected by the findings of low creatinine clearance in both groups.

Possible Link Between the ABO Blood Group of Bioprosthesis Recipients and Specific Types of Structural Degeneration

Background Pigs/bovines share common antigens with humans: α-Gal, present in all pigs/bovines close to the human B-antigen; and AH-histo-blood-group antigen, identical to human AH-antigen and present only in some animals. We investigate the possible impact of patients' ABO blood group on bioprosthesis structural valve degeneration (SVD) through calcification/pannus/tears/perforations for patients ≤60 years at implantation. Methods and Results This was a single-center study (Paris, France) that included all degenerative bioprostheses explanted between 1985 and 1998, mostly porcine bioprostheses (Carpentier-Edwards second/third porcine bioprostheses) and some bovine bioprostheses. For the period 1998 to 2014, only porcine bioprostheses with longevity ≥13 years were included (total follow-up ≥29 years). Except for blood groups, important predictive factors for SVD were prospectively collected (age at implantation/longevity/number/site/sex/SVD types) and analyzed using logistic regression. All variables were available for 500 explanted porcine bioprostheses. By multivariate analyses, the A group was associated with an increased risk of: tears (odds ratio[OR], 1.61; P=0.026); pannus (OR, 1.5; P=0.054), pannus with tears (OR, 1.73; P=0.037), and tendency for lower risk of: calcifications (OR, 0.63; P=0.087) or isolated calcification (OR, 0.67; P=0.17). A-antigen was associated with lower risk of perforations (OR 0.56; P=0.087). B-group patients had an increased risk of: perforations (OR, 1.73; P=0.043); having a pannus that was calcified (OR, 3.0, P=0.025). B-antigen was associated with a propensity for calcifications in general (OR, 1.34; P=0.25). Conclusions Patient's ABO blood group is associated with specific SVD types. We hypothesize that carbohydrate antigens, which may or may not be common to patient and animal bioprosthetic tissue, will determine a patient's specific immunoreactivity with respect to xenograft tissue and thus bioprosthesis outcome in terms of SVD.

Normothermic machine perfusion of ischaemically damaged porcine kidneys with autologous, allogeneic porcine and human red blood cells

In porcine kidney auto-transplant models, red blood cells (RBCs) are required for ex-vivo normothermic machine perfusion (NMP). As large quantities of RBCs are needed for NMP, utilising autologous RBCs would imply lethal exsanguination of the pig that is donor and recipient-to-be in the same experiment. The purpose of this study was to determine if an isolated porcine kidney can also be perfused with allogeneic porcine or human RBCs instead. Porcine kidneys, autologous and allogeneic blood were obtained from a local slaughterhouse. Human RBCs (O-pos), were provided by our transfusion laboratory. Warm ischaemia time was standardised at 20 minutes and subsequent hypothermic machine perfusion lasted 1.5–2.5 hours. Next, kidneys underwent NMP at 37°C during 7 hours with Williams' Medium E and washed, leukocyte depleted RBCs of either autologous, allogeneic, or human origin (n = 5 per group). During perfusion all kidneys were functional and produced urine. No macroscopic adverse reactions were observed. Creatinine clearance during NMP was significantly higher in the human RBC group in comparison with the allogeneic group (P = 0.049) but not compared to the autologous group. The concentration of albumin in the urine was significantly higher in the human RBC group (P <0.001) compared to the autologous and allogeneic RBC group. Injury marker aspartate aminotransferase was significantly higher in the human RBC group in comparison with the allogeneic group (P = 0.040) but not in comparison with the autologous group. Renal histology revealed glomerular and tubular damage in all groups. Signs of pathological hyperfiltration and microvascular injury were only observed in the human RBC group. In conclusion, perfusion of porcine kidneys with RBCs of different origin proved technically feasible. However, laboratory analysis and histology revealed more damage in the human RBC group compared to the other two groups. These results indicate that the use of allogeneic RBCs is preferable to human RBCs in a situation where autologous RBCs cannot be used for NMP.

Importance of the Major Histocompatibility Complex (Swine Leukocyte Antigen) in Swine Health and Biomedical Research

In pigs, the major histocompatibility complex (MHC), or swine leukocyte antigen (SLA) complex, maps to Sus scrofa chromosome 7. It consists of three regions, the class I and class III regions mapping to 7p1.1 and the class II region mapping to 7q1.1. The swine MHC is divided by the centromere, which is unique among mammals studied to date. The SLA complexspans between 2.4 and 2.7 Mb, depending on haplotype, and encodes approximately 150 loci, with at least 120 genes predicted to be functional. Here we update the whole SLA complex based on the Sscrofa11.1 build and annotate the organization for all recognized SLA genes and their allelic sequences. We present SLA nomenclature and typing methods and discuss the expression of SLA proteins, as well as their role in antigen presentation and immune, disease, and vaccine responses. Finally, we explore the role of SLA genes in transplantation and xenotransplantation and their importance in swine biomedical models.

Random allogeneic blood transfusion in pigs: characterisation of a novel experimental model

Background

Organ cross-talk describes interactions between a primary affected organ and a secondarily injured remote organ, particularly in lung-brain interactions. A common theory is the systemic distribution of inflammatory mediators that are released by the affected organ and transferred through the bloodstream. The present study characterises the baseline immunogenic effects of a novel experimental model of random allogeneic blood transfusion in pigs designed to analyse the role of the bloodstream in organ cross-talk.

Methods

After approval of the State and Institutional Animal Care Committee, 20 anesthetized pig were randomized in a donor and an acceptor (each n = 8): the acceptor animals each received high-volume whole blood transfusion from the donor (35–40 ml kg⁻¹). Four animals received balanced electrolyte solution instead of blood transfusion (control group; n = 4). Afterwards the animals underwent extended cardiorespiratory monitoring for eight hours. Post mortem assessment included pulmonary, cerebral and systemic mediators of early inflammatory response (IL-6, TNF-alpha, iNOS), wet to dry ratio, and lung histology.

Results

No adverse events or incompatibilities occurred during the blood transfusion procedures. Systemic cytokine levels and pulmonary function were unaffected. Lung histopathology scoring did not display relevant intergroup differences. Neither within the lung nor within the brain an up-regulation of inflammatory mediators was detected. High volume random allogeneic blood transfusion in pigs neither impaired pulmonary integrity nor induced systemic, lung, or brain inflammatory response.

Conclusion

This approach can represent a novel experimental model to characterize the blood-bound transmission in remote organ injury.

Recipients with blood group A associated with longer survival rates in cardiac valvular bioprostheses

Background

Pigs/bovines share with humans some of the antigens present on cardiac valves. Two such antigens are: the major xenogenic Ag, “Gal” present in all pig/bovine very close to human B-antigen of ABO-blood-group system; the minor Ag, pig histo-blood-group AH-antigen identical to human AH-antigen and present by some animals. We hypothesize that these antigens may modify the immunogenicity of the bioprosthesis and also its longevity. ABO distribution may vary between patients with low (<6 years) and high (≥15 years) bioprostheses longevity.

Methods

Single-centre registry study (Paris, France) including all degenerative porcine bioprostheses (mostly Carpentier-Edwards 2nd/3rd generation heart valves) explanted between 1985 and 1998 and some bovine bioprostheses. For period 1998–2014, all porcine bioprostheses with longevity ≥13 years (follow-up ≥29 years). Important predictive factors for bioprosthesis longevity: number, site of implantation, age were collected. Blood group and other variables were entered into an ordinal logistic regression analysis model predicting valve longevity, categorized as low (<6 years), medium (6–14.9 years), and high (≥15 years).

Findings

Longevity and ABO-blood group were obtained for 483 explanted porcine bioprostheses. Mean longevity was 10.2 ± 3.9 years [0–28] and significantly higher for A-patients than others (P = 0.009). Using multivariate analysis, group A was a strong predictive factor of longevity (OR 2.09; P < 0.001). For the 64 explanted bovine bioprosthesis with low/medium longevity, the association, with A-group was even more significant.

Interpretation

Patients of A-group but not B have a higher longevity of their bioprostheses. Future graft-host phenotyping and matching may give rise to a new generation of long-lasting bioprosthesis for implantation in humans, especially for the younger population.

Fund

None.

Genetically-engineered pigs as sources for clinical red blood cell transfusion: What pathobiological barriers need to be overcome?

An alternative to human red blood cells (RBCs) for clinical transfusion would be advantageous, particularly in situations of massive acute blood loss (where availability and compatibility are limited) or chronic hematologic diseases requiring frequent transfusions (resulting in alloimmunization). Ideally, any alternative must be neither immunogenic nor pathogenic, but readily available, inexpensive, and physiologically effective. Pig RBCs (pRBCs) provide a promising alternative due to their several similarities with human RBCs, and our increasing ability to genetically-modify pigs to reduce cellular immunogenicity. We briefly summarize the history of xenotransfusion, the progress that has been made in recent years, and the remaining barriers. These barriers include prevention of (i) human natural antibody binding to pRBCs, (ii) their phagocytosis by macrophages, and (iii) the T cell adaptive immune response (in the absence of exogenous immunosuppressive therapy). Although techniques of genetic engineering have advanced in recent years, novel methods to introduce human transgenes into pRBCs (which do not have nuclei) will need to be developed before clinical trials can be initiated.

Establishment and identification of cell lines from type O blood Korean native pigs and their efficiency in supporting embryonic development via somatic cell nuclear transfer

Due to their similarities with humans in anatomy, physiology, and genetics miniature pigs are becoming an attractive model for biomedical research. We aim to establish and evaluate blood type O cells derived from Korean native pig (KNP), a typical miniature pig breed in Korea. Ten cell lines derived from 8 KNP piglets and one adult female KNP (kidney and ear tissues) were established. To confirm the presence of blood type O, genomic DNA, fucosyltransferase (FUT) expression, and immunofluorescence staining were examined. Additionally, fluorescence-activated cell sorting and somatic cell nuclear transfer were performed to investigate the normality of the cell lines and to evaluate their effectiveness in embryo development. We found no significant bands corresponding to specific blood group A, and no increase in FUT expression in cell lines derived from piglets No. 1, No. 4, No. 5, No. 8, and the adult female KNP; moreover, they showed normal levels of expression of α 1,3-galactosyltransferase and cytidine monophosphate-N-acetylneuraminic acid hydroxylase. There was no significant difference in embryo development between skin and kidney fibroblasts derived from the blood type O KNPs. In conclusion, we successfully established blood type O KNP cell lines, which may serve as a useful model in xenotransplantation research.

A model of acute renal allograft rejection in outbred Yorkshire piglets

Pigs represent a desirable animal model for the study of rejection in kidney transplantation with inbred Yucatan miniature swine (YMS) the most commonly studied strain due to well defined swine leukocyte antigen (SLA) genotypes. However, limitations to YMS may include cost and availability. Outbred Yorkshire pigs are widely available and significantly cheaper than YMS. Recent advances in SLA genotyping have allowed its application to outbred strains. On this basis, we theorized that Yorkshire pigs would be a viable alternative to YMS for the study of rejection in kidney transplantation. To address this question, we performed auto (Auto) and allotransplants (Allo) in 24 Yorkshire pigs, and assessed SLA genotypes and acute rejection after 72h. At sacrifice, and when compared to autotransplants, allotransplants had significant elevations in serum creatinine (8.4±1.3 vs 2.8±2.0mg/dL for Allo vs autotransplants, respectively) and BUN (61±9 vs 19.2±15mg/dL for Allo vs autotransplants, respectively). Warm ischemia times between the two groups did not differ (24±2.3 vs 26.4±1.4min for Auto vs Allo, respectively). There were 16 distinct SLA haplotypes identified from pigs undergoing allotransplantion, no matched donor-recipient pairs, and all allografts demonstrated rejection. Type IIA cellular rejection (Banff) was the most common. One allograft demonstrated hyperacute rejection due a blood group incompatibility. Histologically, the expression of regulatory Tcells and dendritic cells was increased in allografts. These data suggest that Yorkshire pigs may be a useful model for the study of acute rejection in experimental kidney transplantation.

The A0 blood group genotype modifies the jejunal glycomic binding pattern profile of piglets early associated with a simple or complex microbiota

The intestinal epithelium glycocalyx sugar motif is an important determinant of the bacterial-host interaction and may be affected in pigs by gut microbiota and by blood group genotype. The aim was to study the effect of intestinal association with different microbiota and A0 blood group genotypes on the expressed glycomic pattern in the small intestine. Twelve caesarean-derived pigs previously associated with a simple association (SA) or complex association (CA) microbiota were selected at 26 to 37 d of age. In each subject, different jejunal loops were perfused for 8 h with enterotoxigenic K88 (ETEC), ETEC fimbriae (F4), (LAM), or a saline control. The piglets were genotyped for A0 blood group and the glycomic profile was evaluated by microscopic screening of lectin binding: peanut agglutinin (PNA), which is galactose specific; agglutinin I (UEA), which is fucose specific; lectin II (MALii), which is sialic acid specific; concavalin A, which is mannose specific; soybean agglutinin (SBA), which is -acetyl-galactosamine specific; and wheat germ agglutinin (WGA), which is -acetyl-glucosamine specific. A0 pigs had fewer UEA-positive cells, MALii-positive cells ( < 0.001), and SBA-positive cells ( < 0.10) than 00 pigs. Simple association pigs had more SBA positive cells ( < 0.01) than CA pigs. Enterotoxigenic K88-perfused intestinal loops had fewer UEA-positive cells ( < 0.01) and WGA positive cells ( < 0.001) cells and more PNA positive cells (only in SA pigs, < 0.01). No effects of introduction of F4 and LAM in the intestinal lumen were observed. The porcine A0 blood group genotype and the luminal presence of ETEC strongly affected the jejunal mucosa glycomic pattern profile whereas an early oral simple or complex microbial association had limited effects. Pig genetic background has relevance on the cross talk between intestinal epithelium glycocalyx sugar motif and ETEC and, ultimately, on the gut microbial colonization in later life.

FUT1 genetic variants impact protein glycosylation of porcine intestinal mucosa

A massive use of antibiotics in industrial pig production is a major cause of the rapidly rising bacterial resistance to antibiotics. An enhanced understanding of infectious diseases and of host-microbe interactions has the potential to explore alternative ways to improve pig health and reduce the need for antibiotics. Host-microbe interactions depend on host-expressed glycans and microbe-carrying lectins. In this study, a G > A (nucleotide 307) missense mutation in the porcine α1,2fucosyltransferase 1 gene (FUT1), which has been reported to prevent infections by the common porcine enteric pathogen F18 fimbriated Escherichia coli, provided a unique opportunity to study glycan structures potentially involved in intestinal infections. N- and O-Linked glycans of the intestinal mucosa proteins were characterized in detail using LC-MS/MS. Relative abundances of all glycans were determined and compared between four heterozygous pigs (FUT1-307(A/G)) and four age-matched homozygous pigs from the same 2 litters carrying the missense FUT1 gene constellation (FUT1-307(A/A)). None of the characterized 48 N-linked glycans was found to be regulated by the FUT1 missense mutation, while 11 of the O-linked glycans showed significantly altered abundances between the two genotypes. The overall abundance of H-antigen carrying structures was decreased fivefold, while H-antigen precursors and sialylated structures were relatively more abundant in pigs with the FUT1 missense mutation. These results provide insight into the role of FUT1 on intestinal glycosylation, improve our understanding of how variation in FUT1 can modulate host-microbe interactions, and suggest that the FUT1 genetic variant may help to improve pig gut health.

Failure of neonatal B-cell tolerance induction by ABO-incompatible kidney grafts in piglets

BACKGROUND

ABO-incompatible (ABOi) infant heart transplantation results in B-cell tolerance to graft A/B antigens, confirming human susceptibility to acquired immunologic or "neonatal" tolerance as described originally in murine models. Starting with this clinical observation, we sought to model neonatal ABOi organ transplantation to allow mechanistic studies of tolerance.

METHODS

Plasma anti-A/B antibodies were measured over time in piglets to establish developmental antibody kinetics. Blood group O piglets received kidney allografts from group A (AO-incompatible) or group O (AO-compatible) donors under cyclosporine immunosuppression. Anti-A antibodies were measured serially after transplantation; A/H antigen expression and allograft rejection were assessed in graft biopsies.

RESULTS

Anti-A antibodies developed in naïve piglets in a kinetic pattern analogous to human infants; anti-B remained low. After transplantation, anti-A antibodies developed similarly in AO-incompatible and AO-compatible groups and were not suppressed by cyclosporine. A/H antigen expression was persistent in all graft biopsies; however, A/H antigens were not detected in vascular endothelium. Cellular and antibody-mediated rejection was absent or minimal in early and late biopsies in both groups, with one exception.

CONCLUSIONS

Naturally delayed isohemagglutinin production in piglets is analogous to the developmental kinetics in human infants. However, in contrast to deficient anti-A antibody production as seen long-term after "A-into-O" infant heart transplant recipients, normal anti-A antibody production after "A-into-O" piglet kidney transplantation indicates that tolerance did not develop despite graft A antigen persistence. These findings suggest that the impact on the host immune system of exposure to nonself ABH antigens during early life in human heart versus porcine kidney grafts may depend on expression in vascular endothelium.

Non-ABO blood group systems phenotyping in non-human primates for blood banking laboratory and xenotransplantation

Some biomedical research procedures, such as organ xenotransplantation, usually require intensive hemotherapy. Knowledge of the whole phenotype of blood donor and graft could be useful in the field of xenotransplantation. Human and simian-type categories of blood groups have been established and they can be tested by standard methods used for human blood grouping. The aim of this work was to study the incidence of non-ABO blood group systems in different species of non-human primates, which are employed in biomedical research. The phenotype of Rh, Lewis, Kidd, Kell, MNSs, Lutheran, P and Duffy antigens was investigated in olive baboon (n = 48), chacma baboon (n = 9), Guinea baboon (n = 14), Rhesus macaque (n = 38) and squirrel monkey (n = 30) by using commercial microtyping cards. Kell, Lutheran, Kidd and Duffy antigens have been detected in all species, Rh in squirrel monkey, MNSs in rhesus macaque and squirrel monkey, and Lewis in baboon and rhesus macaque. There were differences in frequency and haemagglutination scores between species regardless of their gender and age. The main differences were found in squirrel monkey when compared with baboons and macaques. This typing system provides a tool to assess the presence of antigens in animals used for experimental procedures, such as xenotransplantation and xenotransfusion.

Myocardial oxidative metabolism and protein synthesis during mechanical circulatory support by extracorporeal membrane oxygenation

Extracorporeal membrane oxygenation (ECMO) provides essential mechanical circulatory support necessary for survival in infants and children with acute cardiac decompensation. However, ECMO also causes metabolic disturbances, which contribute to total body wasting and protein loss. Cardiac stunning can also occur, which prevents ECMO weaning, and contributes to high mortality. The heart may specifically undergo metabolic impairments, which influence functional recovery. We tested the hypothesis that ECMO alters oxidative metabolism and protein synthesis. We focused on the amino acid leucine and integration with myocardial protein synthesis. We used a translational immature swine model in which we assessed in heart 1) the fractional contribution of leucine (FcLeucine) and pyruvate to mitochondrial acetyl-CoA formation by nuclear magnetic resonance and 2) global protein fractional synthesis (FSR) by gas chromatography-mass spectrometry. Immature mixed breed Yorkshire male piglets (n = 22) were divided into four groups based on loading status (8 h of normal circulation or ECMO) and intracoronary infusion [(13)C(6),(15)N]-L-leucine (3.7 mM) alone or with [2-(13)C]-pyruvate (7.4 mM). ECMO decreased pulse pressure and correspondingly lowered myocardial oxygen consumption (∼40%, n = 5), indicating decreased overall mitochondrial oxidative metabolism. However, FcLeucine was maintained and myocardial protein FSR was marginally increased. Pyruvate addition decreased tissue leucine enrichment, FcLeucine, and Fc for endogenous substrates as well as protein FSR. The heart under ECMO shows reduced oxidative metabolism of substrates, including amino acids, while maintaining 1) metabolic flexibility indicated by ability to respond to pyruvate and 2) a normal or increased capacity for global protein synthesis.

α1,3-galactosyltransferase deficiency in germ-free miniature pigs increases N-glycolylneuraminic acids as the xenoantigenic determinant in pig-human xenotransplantation

In this study, we examined whether Hanganutziu-Deicher (H-D) antigens are important as an immunogenic non-α1,3-galactose (Gal) epitope in pigs with a disrupted α1,3-galactosyltransferase gene. The targeting efficiency of the AO blood genotype was achieved (2.2%) in pig fibroblast cells. A total of 1800 somatic cell nuclear transfer (SCNT) embryos were transferred to 10 recipients. One recipient developed to term and naturally delivered two piglets. The α1,3-galactosyltransferase activity in lung, liver, spleen, and testis of heterozygote α1,3-galactosyltransferase gene knockout (GalT-KO) pigs was significantly decreased, whereas brain and heart showed very low decreasing levels of α1,3-galactosyltransferase activity when compared to those of control. Enzyme-linked lectinosorbent assay showed that the heterozygote GalT-KO pig had more sialylα2,6- and sialylα2,3-linked glycan than the control. Furthermore, the heart, liver, and kidney of the heterozygote GalT-KO pig had a higher N-glycolylneuraminic acid (Neu5Gc) content than the control, whereas the lung of the heterozygote GalT-KO pig had Neu5Gc content similar to the control. Collectively, the data strongly indicated that Neu5Gc is a more critical xenoantigen to overcoming the next acute immune rejection in pig to human xenotransplantation.

Gal/non-Gal antigens in pig tissues and human non-Gal antibodies in the GalT-KO era

Our knowledge regarding Gal and non-Gal antigens in GalT-KO pig tissues can be summarized as α3Galactosyl-tranferase gene knock out eliminates the Galα3Galβ4GlcNAc-R antigen expression in pig tissues as well as anti-Gal antibody binding. Other Galα-terminating saccharides (e.g. iGb3 glycolipids and Galα2 determinants) may be present but have not been documented. α3Galactosyl-tranferase gene knock out slightly changes the carbohydrate antigen expression but no "new" antigens recognized by the human immune system have been found. Non-Gal antigens are both of protein and carbohydrate nature but their exact chemical structures are poorly defined. Regarding human non-Gal antibodies our knowledge is as Non-Gal antibodies exist naturally and increase in humans/non-human primate (NHP) receiving WT or GalT-KO pig grafts. Non-Gal antibodies with new antigen epitope recognition can be induced in humans/NHP after challenge by WT or GalT-KO pig grafts. Non-Gal antibodies react with both carbohydrates and proteins. Part of the protein reactivity is directed to glycoprotein carbohydrates chains. Non-Gal antibodies reacting with neuraminic acid terminated saccharides (both N-Acetyl and N-Glycoloyl variants) are present in humans/NHP. Anti-neuraminic acid antibodies are increased, as well as induced, after grafting pig organs into humans/NHP. Non-Gal antibodies does not cause hyperacute xenorejection but can be cytotoxic and cause xenoorgan damage. If humans sensitized to HLA antigens are at a higher risk of rejecting pig xenograft compared with non-sensitized individuals is not fully clarified. Clinical trials are needed to evaluate the relevance of non-Gal antigens/antibodies and for the xenofield to advance.

Identification of new carbohydrate and membrane protein antigens in cardiac xenotransplantation

BACKGROUND

α1,3-Galactosyltransferase gene knockout (GTKO) pigs reduced the significance of antibody to galactose alpha 1,3-galactose (Gal) antigens but did not eliminate delayed xenograft rejection (DXR). We hypothesize that DXR of GTKO organs results from an antibody response to a limited number of non-Gal endothelial cell (EC) membrane antigens. In this study, we screened a retrovirus expression library to identify EC membrane antigens detected after cardiac xenotransplantation.

METHODS

Expression libraries were made from GT:CD46 and GTKO porcine aortic ECs. Viral stocks were used to infect human embryonic kidney cells (HEK) that were selected by flow cytometry for IgG binding from sensitized cardiac heterotopic xenograft recipients. After three to seven rounds of selection, individual clones were assessed for non-Gal IgG binding. The porcine complementary DNA was recovered by polymerase chain reaction amplification, sequenced, and identified by homology comparisons.

RESULTS

A total of 199 and 317 clones were analyzed from GT:CD46 and GTKO porcine aortic EC complementary DNA libraries, respectively. Sequence analysis identified porcine CD9, CD46, CD59, and the EC protein C receptor. We also identified porcine annexin A2 and a glycosyltransferase with homology to the human β1,4 N-acetylgalactosaminyl transferase 2 gene.

CONCLUSION

The identified proteins include key EC functions and suggest that non-Gal antibody responses may compromise EC functions and thereby contribute to DXR. Recovery of the porcine β1,4 N-acetylgalactosaminyl transferase 2 suggests that an antibody response to a SD-like carbohydrate may represent a new carbohydrate moiety involved in xenotransplantation. The identification of these porcine gene products may lead to further donor modification to enhance resistance to DXR and further reduce the level of xenograft antigenicity.

Molecular characterization of the human ABO blood group orthologus system in pigs

The selection and use of animals with blood group 0 in the process of transplanting pig organs or tissues into humans can positively contribute to the control of acute immune rejection due to differences in blood groups. Exon-specific PCRs for the porcine blood group A transferase gene against genomic DNA from either blood group A or 0 animals resulted in the amplification failure of the A0 blood group gene exon 8 from blood group 0 animals. To characterize the genetic abnormality in the genome of blood group 0 animals, we screened bacterial artificial chromosome (BAC) clones from a Korean native pig BAC library which had the blood group 0 allele, and carried out shotgun sequencing. The analysis showed that the 0 allele has a large deletion between exon 7 of the A0 blood group gene and the neighbouring SURF6. We also showed that the ABO blood group antigens in humans and the A0 blood group antigens in pigs are coded by mutations within the orthologous glycosyltransferase gene. In addition, we developed a multiplex genotyping method for the porcine A0 blood group gene.

Structural characterization of alpha1,3-galactosyltransferase knockout pig heart and kidney glycolipids and their reactivity with human and baboon antibodies

BACKGROUND

alpha1,3-galactosyltranferase knockout (GalT-KO) pigs have been established to avoid hyperacute rejection in GalT-KO pig-to-human xenotransplantation. GalT-KO pig heart and kidney glycolipids were studied focusing on elimination of Gal-antigens and whether novel antigens would appear. Non-human primates are used as pre-clinical transplantation experimental models. Therefore, sera from baboons transplanted with GalT-KO hearts were compared with human serum regarding reactivity with pig glycolipids.

METHODS

Neutral and acidic glycolipids were isolated from GalT-KO and WT pig hearts and kidneys. Glycolipid immune reactivity was tested on TLC plates using human affinity-purified anti-Gal Ig, anti-blood group monoclonal antibodies, lectins, and human serum as well as baboon serum collected before and after GalT-KO pig heart transplantations. Selected glycolipid fractions, isolated by HPLC, were structurally characterized by mass spectrometry and proton NMR spectroscopy.

RESULTS

GalT-KO heart and kidney lacked alpha3Gal-terminated glycolipids completely. Levels of uncapped N-acetyllactosamine precursor compounds, blood group H type 2 core chain compounds, the P1 antigen and the x(2) antigen were increased. Human serum antibodies reacted with Gal-antigens and N-glycolylneuraminic acid (NeuGc) in WT organs of which only the NeuGc reactivity remained in the GalT-KO tissues. A clear difference in reactivity between baboon and human antibodies with pig glycolipids was found. This was most pronounced for acidic, not yet identified, compounds in GalT-KO organs which were less abundant or lacking in the corresponding WT tissues.

CONCLUSIONS

GalT-KO pig heart and kidney completely lacked Gal glycolipid antigens whilst glycolipids synthesized by competing pathways were increased. Baboon and human serum antibodies showed a different reactivity pattern to pig glycolipid antigens indicating that non-human primates have limitations as a human pre-clinical model for immune rejection studies.

Genetically engineered pig red blood cells for clinical transfusion: initial in vitro studies

BACKGROUND

Pigs are a potential source of red blood cells (RBCs) and could resolve the shortage of human blood for transfusion. This study investigated in vitro the compatibility of genetically engineered pig RBCs (pRBCs) with the human innate immune response.

STUDY DESIGN AND METHODS

Human volunteers of all ABO blood types were sources of sera and those of O blood type were sources of circulating monocytes/macrophages. RBCs from ABO-compatible (ABO-C) and ABO-incompatible (ABO-I) humans and wild-type (WT) and alpha-1,3-galactosyltransferase gene-knockout (GTKO) pigs were tested for hemagglutination, immunoglobulin (Ig)M/IgG antibody binding, and complement-dependent cytotoxicity (CDC) using human sera. Phagocytosis of RBCs by human monocyte-derived macrophages was measured by coculture in the absence or presence of pooled human O serum.

RESULTS

RBCs showed significant differences (p < 0.01) with regard to hemagglutination, IgM and IgG binding, and CDC (ABO-C < GTKO < ABO-I < WT). In the absence of pooled human O serum (antibodies), there was no phagocytosis of any RBCs; in the presence of serum (antibodies), phagocytosis of ABO-I RBCs was greater than of WT (p < 0.01), which in turn was greater than of GTKO RBCs (p < 0.05).

CONCLUSIONS

GTKO RBCs were significantly more compatible than ABO-I and WT RBCs, but were not comparable to ABO-C combinations. In the presence of antibody, human monocyte-derived macrophages phagocytosed ABO-I RBC/sera combinations more efficiently than pRBCs. These observations contribute to our ultimate goal of using genetically engineered pRBCs for clinical blood transfusion. However, pigs will require other modifications or manipulations if they are to become suitable for human transfusion.

Normal hematology and hematologic disorders in potbellied pigs

Potbellied pigs have become a notable portion of small animal and farm animal practitioners' caseload. Relatively little information is readily accessible for the veterinary practitioner in regard to normal hematologic values or alterations of the hemogram in response to disease, however. This article is a review of blood collection techniques in swine adaptable to potbellied pigs in addition to collection artifacts observed in the swine hemogram. Alterations of the hemogram in disease states that may be encountered in potbellied pig medicine are reviewed.

Studies on glycolipid antigens in small intestine and pancreas from alpha1,3-galactosyltransferase knockout miniature swine

BACKGROUND

To avoid hyperacute rejection of xeno-organs, alpha1,3-galactosyltransferase knockout (GalT-KO) pigs have been produced. Galalpha1,3Gal determinant elimination may expose cryptic carbohydrate antigens and/or generate new antigens. This is the first biochemical study of carbohydrate antigens in GalT-KO pig organs.

METHODS

Neutral and acidic glycolipids were isolated from small intestine and pancreas of two GalT-KO and one wild-type (WT) pig. Glycolipid immune reactivity was tested on thin-layer chromatograms. Small intestine neutral glycolipids were separated by high-performance liquid chromatography and selected fractions were analyzed by proton nuclear magnetic resonance spectroscopy. Total gangliosides were quantified on thin-layer chromatograms and in microtiter wells.

RESULTS

Using Galalpha1,3nLc4 glycolipid reference, total Galalpha1,3Gal glycolipid antigens in the WT animal was estimated at about 30 microg (small intestine) and 3 microg (pancreas) per gram of dry tissue. Galalpha1,3Gal determinants were not detected in GalT-KO tissues at a detection limit of less than 0.25% (small intestine) and 0.5% (pancreas) of the WT tissues. Isoglobotriaosylceramide (iGb3) was absent but trace amounts of Fuc-iGb3 was found in both GalT-KO and WT pig small intestine. Blood group H type 2 core saccharide compounds were increased in GalT-KO pancreas. Total amount of gangliosides was decreased in GalT-KO tissues. The alpha1,3-galactosyltransferase acceptor, N-acetyllactosamine determinant, was not increased in GalT-KO tissues. Human serum antibodies reacted with WT organ Galalpha1,3Gal antigens and gangliosides, of which the ganglioside reactivity remained in GalT-KO tissues.

CONCLUSIONS

Knockout of porcine alpha1,3-galactosyltransferase gene results in elimination of Galalpha1,3Gal-terminated glycolipid compounds. GalT-KO genetic modification did not produce new compensatory glycolipid compounds reactive with human serum antibodies.