Xenotransplantation最新文献

Whole blood and its constituents are primary treatments for numerous human patients with a vast array of clinical conditions. Each year, these include >10 million blood transfusions performed in the USA and approximately 16 million patients globally that receive plasma-derived medicinal products costing $30 billion. As the clinical indications and demand for blood products continue to grow, there is a critical impetus for establishing sources that are more reliable, cost-effective, and efficacious than the current system that is largely built around samples derived from human donors. In particular, genetically-engineered pigs that have been developed for solid organ xenotransplantation could also serve as a source of blood products, representing a potential source for fulfilling global clinical needs. Here we provide an overview of the blood product economy and assess the feasibility of genetically-engineered pigs as a source of clinical-grade blood products for use in human recipients. Although the potential need for these products is immense, we draw attention to the special requirement for them in patients with pig organ grafts.

Porcine endogenous retroviruses (PERVs) are present in the germ lines of domesticated pigs (Sus scrofa) and related suids. There are three types of PERVs, PERV-A, -B, and -C, which differ in their host range. PERV-A and -B can infect human and porcine cells, while PERV-C only infects porcine cells. PERV-A and -B are found in the genomes of all pigs, while PERV-C is found in most but not all pigs. Although many PERV provirus insertions are defective, in vitro culture of porcine cells has produced infectious virions of all three types as well as PERV-A/C recombinants, which show enhanced replication competence. Identifying pigs that are PERV-C negative could help prevent such recombination events and would advance the development of porcine germplasm as a safer source of xenografts for humans. Here, we present the results of extensive screening involving 142 Landrace, Duroc, Large White, and crossbred pigs using up to nine primer pairs to identify putative PERV-C-negative animals. Long-read whole genome sequencing was conducted on a subset of four pigs (one PERV-C PCR positive and three PERV-C PCR putative negatives), which confirmed their status as PERV-C positive or negative, respectively. Our results confirmed that the screened pigs were truly PERV-C negative, establishing the existence of PERV-C-negative germplasm within the herd. These findings support the feasibility of developing or selecting PERV-C-negative pigs as a source of germplasm for xenotransplantation and other biomedical applications.

Genetically engineered porcine organs are redefining the boundaries of clinical xenotransplantation. Zhang et al. now report the first functional pig-to-human liver xenotransplantation in a living patient, demonstrating that a 10-gene-edited auxiliary porcine liver can engraft, produce bile, and synthesize metabolic and coagulation factors in vivo. The xenograft supported a high-risk hepatectomy with borderline remnant volume and contributed to early postoperative stability, although xenotransplant-associated thrombotic microangiopathy ultimately required graft removal. The case highlights both the promise of xenogeneic hepatic support and the physiologic limits that currently preclude durable therapy, including thrombocytopenia, complement-coagulation incompatibility, portal-flow competition, and challenges in assessing dual-graft function. These results establish proof-of-concept for temporary porcine liver support in humans and outline key priorities for next-generation designs: optimized thromboregulation, mitigation of xTMA, improved immunomodulation, and strategies for controlled transition to native-liver autonomy.

This Investigational New Drug (IND) enabling study evaluated life-supporting kidney xenotransplantation using porcine source animals with 10 gene edits (10 GE) in a nonhuman primate (NHP) test system. Twelve baboons received xenografts with either calcineurin inhibitor (CNI)-based or CD40/154 costimulation blockade immunosuppression. Source-specific screening prevented early xenograft antibody-mediated rejection in recipients, and clinically relevant preservation with hypothermic machine perfusion-maintained xenograft viability after off-site procurement at a high health herd facility. No zoonotic infections were detected. Six of 12 recipients achieved survival >3 months without evidence of cell- or antibody-mediated rejection. CNI-based regimens were well-tolerated and achieved the longest survivals to date using this approach, contingent on maintenance of therapeutic drug levels. However, xenograft loss among recipients of each immunosuppression regimen was associated with complement activation and microangiopathy, despite 10 GE Xenokidney expression of hCD46 and hCD55. Complement activation, potentially worsened by infection-related inflammation, may lead to long-term 10 GE Xenokidney failure.

Background: Porcine islet xenotransplantation is limited by the availability of clinically applicable immunosuppressive regimens. We tested four depletional induction strategies and maintenance regimens in a non-human primate (NHP) islet xenotransplant model.

Methods: Genetically modified or wild-type neonatal porcine islets were transplanted via portal vein infusion in diabetic NHPs. Induction consisted of rhesus anti-thymocyte globulin (rhATG) (Group 1, n = 4), anti-CD4 monoclonal antibody (mAb, Group 2, n = 3), or human anti-thymocyte globulin (huATG) tocilizumab (Groups 3 and 4; n = 3 and n = 4, respectively). Maintenance consisted of B7 (Groups 1-3) or anti-CD154 (Group 4) costimulation blockade, tacrolimus transitioned to sirolimus (sirolimus only in Group 4), and mycophenolate mofetil. Xenografts were monitored for blood glucose and porcine c-peptide.

Results: Median graft survivals were <14 days (Group 1), <14 days (Group 2), 99 days (Group 3), and 119 days (Group 4). Insulin independence was achieved in one animal in Group 4. Graft survival significantly correlated with islet dose >40,000 IEQ/kg. Rejection was predominately CD3⁺ T-cell mediated. Selective depletion of CD4⁺ T cells led to increased proliferation of CD8⁺ T cells and CD8⁺ infiltrates.

Conclusions: Induction with huATG/tocilizumab and maintenance with 5c8 led to the best functional outcomes. CD4 T-cell depletion with anti-CD4 mAb induced compensatory CD8 T-cell proliferation and graft infiltration.

The B4GALNT2 gene has become an important target for xenotransplantation because its inactivation reduces the antigenicity of porcine tissues. The growing use of organ-source pig models has led to an increased demand for the rapid creation of these animals. However, the physiological role of this gene in pigs remains poorly understood. In 2015, after generating pigs lacking B4GALNT2 expression, researchers observed a third allele for this gene. Subsequently, another gene, described as B4GALNT2-like, was found in the porcine genome. We have collected data over four years since the production of our first line of xenotransplantation pigs lacking B4GALNT2 and B4GALNT2-like expression. In this study, we were able to show that pig cells expressing B4GALNT2-like also reacted to Dolichos biflorus agglutinin (DBA) lectin, which recognizes GalNAc epitopes. Additionally, we demonstrated that B4GALNT2/B4GALNT2-like knockout embryos were able to be carried to term in females with the same genotype. We hypothesized that the presence of both genes in the porcine genome might have occurred due to duplication, inversion, and reinsertion of part of the Phospho1-B4GALNT2 segment. Finally, the pig B4GALNT2-like gene showed greater similarity to the human, bovine, and murine B4GALNT2 genes than the original pig B4GALNT2. These data clarify the importance of targeting both B4GALNT2 and B4GALNT2-like for xenotransplantation studies and have improved our knowledge about their genomic structure and role in pig reproduction.

Introduction: Non-invasive biomarkers that detect xenograft injury before irreversible damage are essential for improving kidney xenotransplantation outcomes. This study investigated whether xenograft-derived cell-free DNA (xdcfDNA) is helpful as a non-invasive, early biomarker of antibody-mediated rejection.

Methods: Kidneys from genetically engineered pigs (GGTA1/CMAH/iGb3s/B4GalNT2 knockout; CD39, CD55, CD46, TBM knock-in) were transplanted into 10 cynomolgus monkeys, which received thymoglobulin, rituximab, anti-CD154 monoclonal antibody, corticosteroid, tacrolimus, and mycophenolate mofetil. Plasma xdcfDNA was measured using species-specific quantitative polymerase chain reaction. Pathological scoring and rejection diagnosis of the kidney xenograft biopsy were performed based on the Banff 2022 criteria.

Results: XdcfDNA levels increased markedly before an overt increase in serum levels of creatinine and blood urea nitrogen after kidney xenotransplantation. When recipients were classified into low- and high-score groups based on the Banff score of kidney xenograft biopsy, xdcfDNA levels were higher in the high-score groups for intimal arteritis (v), composite vasculitis (g + ptc + v), tubular atrophy (ct), interstitial fibrosis (ci), and IgG deposition. Furthermore, the rejection group showed higher xdcfDNA levels than the non-rejection group (p = 0.0270). The cut-off xdcfDNA value for xenograft rejection was 2.545%, with an apparent sensitivity of 100% (95% confidence interval, 64.57%-100.00%) and specificity of 100% (43.85%-100.00%).

Conclusions: XdcfDNA is a potentially sensitive, noninvasive, and early biomarker of xenograft rejection, capturing vasculitis and subsequent chronic injury. Periodic monitoring of xdcfDNA could support noninvasive screening of rejection before overt functional changes in xenografts emerge and might contribute to guiding confirmatory xenograft biopsy and subsequent immunosuppression modification.

Purpose: To compare the effectiveness and prognosis of lamellar keratoplasty (LK) using human cornea and acellular porcine corneal stroma (APCS) for noninfectious peripheral ulcerative keratitis (PUK).

Methods: Fifty-eight patients with noninfectious PUK who underwent LK from 2013 to 2023 were included in this retrospective study. Patients were divided into human cornea (n = 27) and APCS (n = 31) groups according to corneal graft material. The primary outcome was best-corrected visual acuity (BCVA) at 1, 3, 6, and 12 months postoperatively. Kaplan-Meier analysis was used to evaluate graft survival rates within 12 months.

Results: BCVA improved in both groups. The human cornea group had better BCVA at 3 months (p = 0.045) and 6 months (p = 0.010) postoperatively, but no significant difference was observed at 1 or 12 months (p > 0.05). Corneal epithelial healing time was similar overall, but prolonged in the APCS group among patients with autoimmune diseases (p = 0.012). The number of transparent corneal grafts was higher in the human cornea group at 1, 3, and 6 months (p < 0.05), but comparable at 12 months (p > 0.05). Complications occurred in 13 APCS patients and 10 human cornea patients (p > 0.05). Graft survival rates were 80.6% for APCS and 88.8% for human cornea at 12 months (p > 0.05).

Conclusion: APCS is a feasible alternative for noninfectious PUK, with promising visual recovery and long-term outcomes. However, its midterm effectiveness may be slightly inferior, especially in patients with autoimmune diseases, suggesting a need for tailored approaches.

Kidney allotransplantation remains the optimal treatment for end-stage renal disease, but the shortage of donor organs is a persistent issue. Xenotransplantation using gene-edited pig kidneys has shown promise in overcoming this limitation. However, there remain hurdles that include ischemic injury during transportation. The impact of prolonged storage on gene-edited porcine kidneys is not well understood, and few studies have evaluated preservation methods under conditions relevant to xenotransplantation. The present review examines various methods of kidney preservation, focusing on their applicability to xenotransplantation. Methods such as static cold storage (SCS), hypothermic machine perfusion (HMP), and normothermic machine perfusion (NMP) each offer advantages and drawbacks. SCS is widely used but can lead to poor outcomes when kidneys are stored for extended periods. HMP improves renal function and reduces ischemia-reperfusion injury but is limited by its low-temperature metabolic restrictions and benefits from oxygenation. NMP, by maintaining kidneys at physiological temperatures, allows for metabolic activity and real-time viability assessment, though it is associated with logistical challenges. Recent studies suggest that for long periods of storage NMP may better preserve kidney function than HMP. Techniques such as supercooling and partial freezing are in their infancy but offer the prospect of long-term preservation. In summary, long-term storage of pig kidneys could become feasible with advances in machine perfusion or supercooling/cryopreservation techniques. If successful, these innovations would enable the global distribution of gene-edited pig kidneys. However, if meaningful results are to be obtained that are relevant to clinical pig kidney xenotransplantation, future preclinical studies need to be much simpler than those carried out in relation to kidney allotransplantation.

Introduction: With the advent of genome editing technology, xenotransplantation has been attracting attention in recent years as a potential solution to the shortage of organs for transplantation. In Japan, several Japanese universities have reportedly been preparing for the first Japanese clinical trial. However, xenotransplantation poses social issues. Therefore, it is necessary to understand the public's awareness and opinions of it, and policymakers and researchers of xenotransplantation must prepare for social issues.

Materials and methods: In December 2024, an online survey was conducted on Japanese aged 20 to 79, asking questions about their awareness, acceptability, and preferred transplant method. IBM SPSS was used for statistical analysis, and correlations with attributes were also examined.

Results: Valid responses were obtained from 3209 people (response rate: 10.8%). Only 34.6% knew the meaning of xenotransplantation, and 53.8% had a favorable opinion about xenotransplantation being performed as a medical treatment in the future. However, 77.0% predicted that they would feel uncomfortable if a doctor suggested xenotransplantation to them, and 60.9% predicted that they would decide not to undergo xenotransplantation. Fifty-eight percent responded that they would be anxious about discrimination, and 88.2% responded that they would be anxious about being infected with animal-derived pathogens if they received a xenotransplant. In addition, only 1.7% ranked xenotransplantation as their first preference.

Conclusion: The results imply the Japanese public is not ready enough to accept xenotransplantation. This study proposes four points that policymakers and researchers should prepare for social issues before the clinical trial begins in Japan.