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Journal of Hepatology Jun 2023With the increasing number of accepted candidates on waiting lists worldwide, there is an urgent need to expand the number and the quality of donor livers. Dynamic... (Review)
Review
With the increasing number of accepted candidates on waiting lists worldwide, there is an urgent need to expand the number and the quality of donor livers. Dynamic preservation approaches have demonstrated various benefits, including improving liver function and graft survival, and reducing liver injury and post-transplant complications. Consequently, organ perfusion techniques are being used in clinical practice in many countries. Despite this success, a proportion of livers do not meet current viability tests required for transplantation, even with the use of modern perfusion techniques. Therefore, devices are needed to further optimise machine liver perfusion - one promising option is to prolong machine liver perfusion for several days, with ex situ treatment of perfused livers. For example, stem cells, senolytics, or molecules targeting mitochondria or downstream signalling can be administered during long-term liver perfusion to modulate repair mechanisms and regeneration. Besides, today's perfusion equipment is also designed to enable the use of various liver bioengineering techniques, to develop scaffolds or for their re-cellularisation. Cells or entire livers can also undergo gene modulation to modify animal livers for xenotransplantation, to directly treat injured organs or to repopulate such scaffolds with "repaired" autologous cells. This review first discusses current strategies to improve the quality of donor livers, and secondly reports on bioengineering techniques to design optimised organs during machine perfusion. Current practice, as well as the benefits and challenges associated with these different perfusion strategies are discussed.
Topics: Animals; Liver Transplantation; Organ Preservation; Liver; Perfusion; Bioengineering
PubMed: 37208105
DOI: 10.1016/j.jhep.2023.02.009 -
Nature Aug 2022After cessation of blood flow or similar ischaemic exposures, deleterious molecular cascades commence in mammalian cells, eventually leading to their death. Yet with...
After cessation of blood flow or similar ischaemic exposures, deleterious molecular cascades commence in mammalian cells, eventually leading to their death. Yet with targeted interventions, these processes can be mitigated or reversed, even minutes or hours post mortem, as also reported in the isolated porcine brain using BrainEx technology. To date, translating single-organ interventions to intact, whole-body applications remains hampered by circulatory and multisystem physiological challenges. Here we describe OrganEx, an adaptation of the BrainEx extracorporeal pulsatile-perfusion system and cytoprotective perfusate for porcine whole-body settings. After 1 h of warm ischaemia, OrganEx application preserved tissue integrity, decreased cell death and restored selected molecular and cellular processes across multiple vital organs. Commensurately, single-nucleus transcriptomic analysis revealed organ- and cell-type-specific gene expression patterns that are reflective of specific molecular and cellular repair processes. Our analysis comprises a comprehensive resource of cell-type-specific changes during defined ischaemic intervals and perfusion interventions spanning multiple organs, and it reveals an underappreciated potential for cellular recovery after prolonged whole-body warm ischaemia in a large mammal.
Topics: Animals; Cell Death; Cell Survival; Cytoprotection; Gene Expression Profiling; Ischemia; Organ Specificity; Perfusion; Swine; Warm Ischemia
PubMed: 35922506
DOI: 10.1038/s41586-022-05016-1 -
American Journal of Transplantation :... Feb 2023The American Society of Transplant Surgeons supports efforts to increase the number of organs that are critically needed for patients desperately awaiting... (Review)
Review
The American Society of Transplant Surgeons supports efforts to increase the number of organs that are critically needed for patients desperately awaiting transplantation. In the United States, transplantation using organs procured from donation after circulatory death (DCD) donors has continued to increase in number. Despite these increases, substantial variability in the utilization and practices of DCD transplantation still exists. To improve DCD organ utilization, it is important to create a set of best practices for DCD recovery. The following recommendations aim to provide guidance on contemporary issues surrounding DCD organ procurement in the United States. A work group was composed of members of the American Society of Transplant Surgeon Scientific Studies Committee and the Thoracic Organ Transplantation Committee. The following topics were identified by the group either as controversial or lacking standardization: prewithdrawal preparation, definition of donor warm ischemia time, DCD surgical technique, combined thoracic and abdominal procurements, and normothermic regional perfusion. The proposed recommendations were classified on the basis of the grade of available evidence and the strength of the recommendation. This information should be valuable for transplant programs as well as for organ procurement organizations and donor hospitals as they develop robust DCD donor procurement protocols.
Topics: Humans; United States; Tissue and Organ Procurement; Organ Transplantation; Tissue Donors; Cardiovascular System; Perfusion; Death; Organ Preservation
PubMed: 36695685
DOI: 10.1016/j.ajt.2022.10.009 -
JAMA Surgery Mar 2022Ischemic cold storage (ICS) of livers for transplant is associated with serious posttransplant complications and underuse of liver allografts. (Randomized Controlled Trial)
Randomized Controlled Trial
IMPORTANCE
Ischemic cold storage (ICS) of livers for transplant is associated with serious posttransplant complications and underuse of liver allografts.
OBJECTIVE
To determine whether portable normothermic machine perfusion preservation of livers obtained from deceased donors using the Organ Care System (OCS) Liver ameliorates early allograft dysfunction (EAD) and ischemic biliary complications (IBCs).
DESIGN, SETTING, AND PARTICIPANTS
This multicenter randomized clinical trial (International Randomized Trial to Evaluate the Effectiveness of the Portable Organ Care System Liver for Preserving and Assessing Donor Livers for Transplantation) was conducted between November 2016 and October 2019 at 20 US liver transplant programs. The trial compared outcomes for 300 recipients of livers preserved using either OCS (n = 153) or ICS (n = 147). Participants were actively listed for liver transplant on the United Network of Organ Sharing national waiting list.
INTERVENTIONS
Transplants were performed for recipients randomly assigned to receive donor livers preserved by either conventional ICS or the OCS Liver initiated at the donor hospital.
MAIN OUTCOMES AND MEASURES
The primary effectiveness end point was incidence of EAD. Secondary end points included OCS Liver ex vivo assessment capability of donor allografts, extent of reperfusion syndrome, incidence of IBC at 6 and 12 months, and overall recipient survival after transplant. The primary safety end point was the number of liver graft-related severe adverse events within 30 days after transplant.
RESULTS
Of 293 patients in the per-protocol population, the primary analysis population for effectiveness, 151 were in the OCS Liver group (mean [SD] age, 57.1 [10.3] years; 102 [67%] men), and 142 were in the ICS group (mean SD age, 58.6 [10.0] years; 100 [68%] men). The primary effectiveness end point was met by a significant decrease in EAD (27 of 150 [18%] vs 44 of 141 [31%]; P = .01). The OCS Liver preserved livers had significant reduction in histopathologic evidence of ischemia-reperfusion injury after reperfusion (eg, less moderate to severe lobular inflammation: 9 of 150 [6%] for OCS Liver vs 18 of 141 [13%] for ICS; P = .004). The OCS Liver resulted in significantly higher use of livers from donors after cardiac death (28 of 55 [51%] for the OCS Liver vs 13 of 51 [26%] for ICS; P = .007). The OCS Liver was also associated with significant reduction in incidence of IBC 6 months (1.3% vs 8.5%; P = .02) and 12 months (2.6% vs 9.9%; P = .02) after transplant.
CONCLUSIONS AND RELEVANCE
This multicenter randomized clinical trial provides the first indication, to our knowledge, that normothermic machine perfusion preservation of deceased donor livers reduces both posttransplant EAD and IBC. Use of the OCS Liver also resulted in increased use of livers from donors after cardiac death. Together these findings indicate that OCS Liver preservation is associated with superior posttransplant outcomes and increased donor liver use.
TRIAL REGISTRATION
ClinicalTrials.gov Identifier: NCT02522871.
Topics: Death; Female; Humans; Liver; Liver Transplantation; Living Donors; Male; Middle Aged; Organ Preservation; Perfusion
PubMed: 34985503
DOI: 10.1001/jamasurg.2021.6781 -
The Lancet. Microbe Dec 2021Hypervirulent (hv) strains of capsule type K1 and K2 cause invasive infections associated with hepatic abscesses, which can be difficult to treat and are frequently...
BACKGROUND
Hypervirulent (hv) strains of capsule type K1 and K2 cause invasive infections associated with hepatic abscesses, which can be difficult to treat and are frequently associated with relapsing infections. Other strains (non-hv), including lineages that have acquired carbapenem resistance, do not manifest this pathology. In this work we aimed to test the hypothesis that within-macrophage replication is a key mechanism underpinning abscess formation in hv infections.
METHODS
In this exploratory investigation, to study the pathophysiology of abscess formation, mice were intravenously infected with 10 colony forming units (CFU) of either hv isolates (six strains) or non-hv isolates (seven strains). Intracellular bacterial replication and neutrophil influx in liver and spleen was quantified by fluorescence microscopy of sliced cryopreserved organs of mice collected 30 min, 6 h, and 24 h after infection with the aim to provide data of bacterial association to Kupffer cells in the liver and to the different tissue macrophages in the spleen. Microbiological and microscopy analysis of an ex-vivo model of pig liver and spleen infection were used to confirm within-macrophage replication. Pig organs were perfused with heparinised, autologous pig's blood and injected with 6·5 × 10 CFU of hv K2 sequence type 25 strain GMR151. Blood and tissue biopsies collected before infection and 30 min, 1 h, 2 h, 3 h, 4 h, and 5 h after infection were used to measure bacterial counts and to identify the subcellular localisation of bacteria by immunohistochemistry analysis.
FINDINGS
We show that hv resisted phagocyte-mediated clearance and replicated in mouse liver macrophages to form clusters 6 h after infection, with a mean of 7·0 bacteria per Kupffer cell (SD 6·2); however, non-hv were efficiently cleared (mean 1·5 bacteria per cell [SD 1·1]). Hv infection promoted neutrophil recruitment to sites of infection, which in the liver resulted in histopathological signs of abscess formation as early as 24 h post-infection. Experiments in pig organs which share a high functional and anatomical resemblance to human organs, provided strong evidence for the propensity of hv to replicate within the hepatic macrophages.
INTERPRETATION
These findings show subversion of innate immune processes in the liver by and resistance to Kupffer cell mediated clearance as an explanation for the propensity of hv strains to cause hepatic abscesses.
FUNDING
University of Oxford and a Royal Society Wolfson grant funded biosafety facility.
Topics: Animals; Klebsiella Infections; Klebsiella pneumoniae; Liver Abscess; Macrophages; Mice; Perfusion; Swine; Virulence
PubMed: 34901898
DOI: 10.1016/S2666-5247(21)00195-6 -
Nature Communications Apr 2023Normothermic machine perfusion (NMP) has emerged as an innovative organ preservation technique. Developing an understanding for the donor organ immune cell composition...
Normothermic machine perfusion (NMP) has emerged as an innovative organ preservation technique. Developing an understanding for the donor organ immune cell composition and its dynamic changes during NMP is essential. We aimed for a comprehensive characterization of immune cell (sub)populations, cell trafficking and cytokine release during liver NMP. Single-cell transcriptome profiling of human donor livers prior to, during NMP and after transplantation shows an abundance of CXC chemokine receptor 1/2 (CXCR1/CXCR2) neutrophils, which significantly decreased during NMP. This is paralleled by a large efflux of passenger leukocytes with neutrophil predominance in the perfusate. During NMP, neutrophils shift from a pro-inflammatory state towards an aged/chronically activated/exhausted phenotype, while anti-inflammatory/tolerogenic monocytes/macrophages are increased. We herein describe the dynamics of the immune cell repertoire, phenotypic immune cell shifts and a dominance of neutrophils during liver NMP, which potentially contribute to the inflammatory response. Our findings may serve as resource to initiate future immune-interventional studies.
Topics: Humans; Aged; Liver Transplantation; Liver; Perfusion; Organ Preservation; Sequence Analysis, RNA
PubMed: 37085477
DOI: 10.1038/s41467-023-37674-8 -
Transplant International : Official... Jan 2021There has been increasing use of organs from extended criteria or donation after circulatory death donors to meet the demands of the transplant waiting list. Over the... (Review)
Review
There has been increasing use of organs from extended criteria or donation after circulatory death donors to meet the demands of the transplant waiting list. Over the past decade, there has been considerable progress in technologies to preserve organs prior to transplantation to improve the function of these marginal organs. This has led to the development of normothermic machine perfusion, whereby an organ is perfused with warmed, oxygenated blood and nutrients to resume normal physiological function in an isolated ex-vivo platform. With this advance in preservation comes significant opportunities to recondition, repair and regenerate organs prior to transplantation using cellular therapies. This review aims to discuss the possibilities of machine perfusion technology; highlighting the potential for organ-directed reconditioning and the future avenues for investigation in this field.
Topics: Cell- and Tissue-Based Therapy; Humans; Liver Transplantation; Organ Preservation; Perfusion; Tissue Donors
PubMed: 33131097
DOI: 10.1111/tri.13780 -
The Journal of Extra-corporeal... Mar 2022Standards and guidelines for cardiopulmonary bypass have been established by various professional societies. They serve as an instrument to guide safe and effective...
Standards and guidelines for cardiopulmonary bypass have been established by various professional societies. They serve as an instrument to guide safe and effective patient care. We conducted a survey of practicing perfusionists in Kenya to learn about their background, education, current clinical practice and about their knowledge, and attitude regarding standards and guidelines. Two multiple-choice surveys were distributed to all known practicing perfusionist in Kenya using SurveyMonkey (San Mateo, CA). Multiple-choice questions related to professional background, training, annual procedure volume, staffing models, clinical practices, the use of safety devices, and the use of checklists were included in the questionnaires. The survey also inquired about familiarity with American and European perfusion practice standards and guidelines and opinions on establishing standards in Kenya. Responses were received from 12 perfusionists practicing at 10 centers. Professional backgrounds included anesthesia nursing, clinical officers, and critical care nursing. Sixty-seven percent (8/12) received formal training and 33% (4/12) trained primarily through clinical instruction. Of those that received formal training, 63% (5/8) received 1-2 years of training, 25% (2/8) <1 year but more than 6 months, and 12.5% (1/8) received 6 months of formal training. The median clinical experience was 5 years (range 1-22). The median annual case load was 54 (range 0-100). Use of safety devices was reported as follows: level sensor 75% (9/12), air bubble detector 17% (2/12), one-way vent valves 67% (8/12), continuous venous oxygen saturation monitoring 25% (3/12), and gas supply analyzers 33% (4/12). More than one-third of the respondents had no knowledge of the American and European perfusion practice standards, and nearly two-thirds were aware of or had read them. This survey provides contextual information about perfusion practice in Kenya in 2021. There was consensus among perfusionists to develop standards and practice guidelines for Kenya.
Topics: Humans; Kenya; Perfusion; Cardiopulmonary Bypass; Surveys and Questionnaires
PubMed: 36380824
DOI: 10.1182/ject-5-18 -
Current Opinion in Organ Transplantation Feb 2020To summarise recently published studies of donor pretreatment and machine perfusion strategies in kidney transplantation. (Review)
Review
PURPOSE OF REVIEW
To summarise recently published studies of donor pretreatment and machine perfusion strategies in kidney transplantation.
RECENT FINDINGS
The sparsity of donor pretreatment trials has resulted in the re-analysis of already existing data, and RCTs are urgently needed to reinvigorate this aspect of donor research. Uncontrolled donation after circulatory death kidney transplantation has the highest risk of delayed graft function and graft failure, and recent studies have reported that normothermic regional perfusion improves graft function and survival in this setting. Hypothermic machine perfusion reduces delayed graft function following deceased donor kidney transplantation across donor types but unanswered questions still remain regarding its use. The use of oxygenated hypothermic machine perfusion appears to improve graft function in controlled donation after circulatory death mediated by a reduction in acute rejection. Ex-situ normothermic perfusion is emerging and while technically challenging it may facilitate the delivery of pretreatments.
SUMMARY
RCTs are urgently needed to reinvigorate research into donor pretreatment and to establish the place of specific preservation techniques in deceased donor kidney transplantation.
Topics: Humans; Organ Preservation; Organ Transplantation; Perfusion; Tissue Donors
PubMed: 31834008
DOI: 10.1097/MOT.0000000000000725 -
Advanced Healthcare Materials May 2021Engineering functional human tissues in vitro is currently limited by difficulty replicating the small caliber, complex connectivity, cellularity, and 3D curvature of...
Engineering functional human tissues in vitro is currently limited by difficulty replicating the small caliber, complex connectivity, cellularity, and 3D curvature of the native microvasculature. Multiphoton ablation has emerged as a promising technique for fabrication of microvascular structures with high resolution and full 3D control, but cellularization and perfusion of complex capillary-scale structures has remained challenging. Here, multiphoton ablation combined with guided endothelial cell growth from pre-formed microvessels is used to successfully create perfusable and cellularized organ-specific microvascular structures at anatomic scale within collagen hydrogels. Fabrication and perfusion of model 3D pulmonary and renal microvascular beds is demonstrated, as is replication and perfusion of a brain microvascular unit derived from in vivo data. Successful endothelialization and blood perfusion of a kidney-specific microvascular structure is achieved, using laser-guided angiogenesis. Finally, proof-of-concept hierarchical blood vessels and complex multicellular models are created, using multistep patterning with multiphoton ablation techniques. These successes open new doors for the creation of engineered tissues and organ-on-a-chip devices.
Topics: Ablation Techniques; Endothelial Cells; Humans; Microvessels; Perfusion; Tissue Engineering; Veins
PubMed: 33586357
DOI: 10.1002/adhm.202100031