Risk Factors for High Mortality on the Liver Transplant Waiting List in Times of Organ Shortage: A Single-Center Analysis

Effect of recipient age on prioritisation for liver transplantation in the UK: a population-based modelling study

BACKGROUND

Following the introduction of an algorithm aiming to maximise life-years gained from liver transplantation in the UK (the transplant benefit score [TBS]), donor livers were redirected from younger to older patients, mortality rate equalised across the age range and short-term waiting list mortality reduced. Understanding age-related prioritisation has been challenging, especially for younger patients and clinicians allocating non-TBS-directed livers. We aimed to assess age-related prioritisation within the TBS algorithm by modelling liver transplantation prioritisation based on data from a UK transplant unit and comparing these data with other regions.

METHODS

In this population-based modelling study, serum parameters and age at liver transplantation assessment of patients attending the Scottish Liver Transplant Unit, Edinburgh, UK, between December, 2002, and November, 2023, were combined with representative synthetic data to model TBS survival predictions, which were compared according to age group (25-49 years vs ≥60 years), chronic liver disease severity, and disease cause. Models for end-stage liver disease (UKELD [UK], MELD [Eurotransplant region], and MELD 3.0 [USA]) were used as validated comparators of liver disease severity.

FINDINGS

Of 2093 patients with chronic liver disease, 1808 (86%) had complete datasets and liver disease parameters consistent with eligibility for the liver transplant waiting list in the UK (UKELD ≥49). Disease severity as assessed by UKELD, MELD, and MELD 3.0 did not differ by age (median UKELD scores of 56 for patients aged ≥60 years vs 56 for patients aged 25-49 years; MELD scores of 16 vs 16; and MELD 3.0 scores of 18 vs 18). TBS increased with advancing age (R=0·45, p<0·0001). TBS predicted that transplantation in patients aged 60 years or older would provide a two-fold greater net benefit at 5 years than in patients aged 25-49 years (median TBS 1317 [IQR 1116-1436] in older patients vs 706 [411-1095] in younger patients; p<0·0001). Older patients were predicted to have shorter survival without transplantation than younger patients (263 days [IQR 144-473] in older patients vs 861 days [448-1164] in younger patients; p<0·0001) but similar survival after transplantation (1599 days [1563-1628] vs 1573 days [1525-1614]; p<0·0001). Older patients could reach a TBS for which a liver offer was likely below minimum criteria for transplantation (UKELD <49), whereas many younger patients were required to have high-urgent disease (UKELD >60). US and Eurotransplant programmes did not prioritise according to age.

INTERPRETATION

The UK liver allocation algorithm prioritises older patients for transplantation by predicting that advancing age increases the benefit from liver transplantation. Restricted follow-up and biases in waiting list data might limit the accuracy of these benefit predictions. Measures beyond overall waiting list mortality are required to fully capture the benefits of liver transplantation.

FUNDING

None.

Safety and efficacy of Single-Pass Albumin Dialysis (SPAD), Prometheus, and Molecular Adsorbent Recycling System (MARS) liver haemodialysis vs. Standard Medical Therapy (SMT): meta-analysis and systematic review

Introduction

Because not all liver dysfunction patients are suitable for transplantations and there is a shortage of grafts, liver support therapies have gained interest. In this regard, extracorporeal albumin dialysis devices such as single-pass albumin dialysis (SPAD), Prometheus, and molecular adsorbent recycling system (MARS) have been valuable in supplementing standard medical therapy (SMT). However, the efficacy and safety of these devices is often questioned.Aim: We performed a systematic review to summarize the efficacy and safety of MARS, SPAD, and Prometheus as supportive treatments for liver dysfunction.

Material and methods

PubMed, Medline, Cochrane Library, Web of Science, and Google Scholar electronic databases were extensively searched for all randomized trials published in English. In addition, meta-analytic analyses were performed with Review Manager software, and Cochrane's risk of bias tool embedded in this software was used for bias assessment.

Results

Twelve trials including a total of 653 patients were eligible for inclusion. Subgroup analyses of data from these trials revealed that MARS and Prometheus were associated with significant removal of bilirubin (MD = -5.14 mg/dl; 95% CI: -7.26 - -3.02; p < 0.00001 and MD = -8.11 mg/dl; 95% CI: -12.40 - -3.82; p = 0.0002, respectively) but not bile acids and ammonia when compared to SMT. Furthermore, MARS was as effective as Prometheus and SPAD in the reduction of bilirubin (MD = 2.98 mg/dl; 95% CI: -4.26 - 10.22; p = 0.42 and MD = 0.67 mg/dl; 95% CI: -2.22 - 3.56; p = 0.65), bile acids (MD = -17.06 µmol/l; 95% CI: -64.33 - 30.20; p = 0.48 and MD = 16.21 µmol/l; 95% CI: -17.26 - 49.68; p = 0.34), and ammonia (MD = 26 µmol/l; 95% CI: -12.44 - 64.44; p = 0.18). In addition, MARS had a considerable effect in improving hepatic encephalopathy (HE) (RR = 1.54; 95% CI: 1.15-2.05; p = 0.004). However, neither MARS nor Prometheus had a mortality benefit compared to SMTRR (0.86; 95% CI: 0.71-1.03; p = 0.11 and RR = 0.87; 95% CI: 0.66-1.14; p = 0.31, respectively).

Conclusions

MARS, SPAD, and Prometheus, as liver support therapies, are equally effective in reducing albumin-bound and water-soluble substances. Moreover, MARS is associated with HE improvement. However, none of the therapies was associated with a significant reduction in mortality or adverse events.

The impact of center volume on the utilization and outcomes of machine perfusion technology in liver transplantation: An international survey

INTRODUCTION

Machine perfusion (MP) was developed to expand the donor pool and improve liver transplantation (LT) outcomes. Despite optimal results in clinical trials, the real-world MP benefit in centers with low-/mid-volume activity (LVCs) is still being determined.

METHODS

Online survey on MP for LT, distributed to worldwide LT-centers representatives. Variables of interest included logistics, technicalities, and outcomes. Responders were grouped into high-volume centers (HVCs) (>60 LTs/year) and LVCs and results compared.

RESULTS

Sixty-seven centers were included, 36 HVCs and 31 LVCs. Significant differences in MP regarded: (I) existence of an established program (80.6% vs. 41.9%; p = 0.02), (II) presence of a dedicated perfusionist (58.3% vs. 22.6%; p = 0.006), (III) duration (>4 h: 47.2% vs. 16.1%; p = 0.01), (IV) routine use (20%-40% vs. 5%-20%; p = 0.002), (V) graft utilization (>50%: 75% vs. 51.6%; p = 0.009), (VI) 90-day patient-survival (90%-100% vs. 50%-90%; p = 0.001) and (VII) subjectively perceived benefit (always vs. only in selected ECD; p = 0.009). Concordance was found for indications, type, viability tests, graft-salvage, 90-day graft-loss, and major-complications.

CONCLUSIONS

This study captured a picture of MP in real-world LT-practice. Significant disparities have surfaced between LVCs and HVCs regarding logistics, utilization, and results. To close this gap, efforts should be made to more efficiently deliver dedicated support, training and mentoring to LVC teams adopting MP technology.

Rifaximin Reduces Risk of All-Cause Hospitalization in Cirrhotic Liver Transplant Candidates with Hepatic Encephalopathy

In cirrhotic patients listed for liver transplantation (LT) with a history of hepatic encephalopathy (HE), rifaximin reduces the number of hospitalizations, but whether it influences the time to first hospitalization is unknown.

AIMS

to evaluate the time-dependent impact of rifaximin on the risk of all-cause hospitalization and dropout in patients on the LT waiting list.

METHODS

Consecutive patients listed for LT were retrospectively enrolled. After balancing populations with and without rifaximin treatment using the inverse probability therapy weighting analysis, Fine-Gray multivariable competing risk analyses were run to explore risk factors for the first episode of hospitalization and dropout.

RESULTS

When comparing 92 patients taking rifaximin to the untreated group of 152, rifaximin treatment was not associated with any of the study outcomes. In the subset of patients with a history of HE at waitlist entry (N = 81 rifaximin-treated and N = 39 untreated), rifaximin intake was independently associated with a lower risk of hospitalization for all causes (SHR 0.638; 95.0% CI 0.418-0.973; p = 0.037) and for HE (SHR 0.379; 95.0% CI 0.207-0.693; p = 0.002).

CONCLUSIONS

cirrhotic LT candidates with a prior history of HE rifaximin treatment are associated with a lower risk of time-dependent all-cause hospitalization, likely due to its unique effect on gut microbiome composition/function.

Validation of MELD 3.0 scoring system in East Asian patients with cirrhosis awaiting liver transplantation

Recently, a new predictive model that jointly considers the Model of End-stage Liver Disease (MELD) 3.0 and albumin has been proposed. This study investigated the performance of the MELD 3.0 score in predicting the 3-month survival of East Asian patients with cirrhosis compared with the other MELD-based scores. Validation was performed with the retrospective data of 2153 patients in South Korea who were listed for liver transplantation (LT). Discrimination and calibration analyses were performed using the MELD-based scores as an independent variable. On average, patients had the original MELD score of 18.70 ± 9.65. Alcohol (39.99%) and chronic HBV (38.55%) were the 2 main etiologies. The MELD 3.0 with albumin showed slightly better discrimination [c-index = 0.738, incremental AUC (iAUC) = 0.719] compared with the MELD 3.0 without albumin (c-index = 0.737, iAUC = 0.715), MELD-Na (c-index = 0.730, iAUC = 0.707), or the original MELD (c-index = 0.718, iAUC = 0.687) for predicting 3-month survival but not significantly different compared with prior models. Likewise, in the stratified analysis according to the strata of MELD, although the performance of MELD 3.0 was better throughout all the MELD strata than MELD original, there was no statistical difference in performance. The MELD 3.0 with albumin reclassified 22.61% of cases classified by the original MELD to higher MELD score categories, and there was no significant difference in the reclassification rate between males and females. The predictive power of the MELD-based system is lower in Asian populations than in western countries. Nonetheless, the MELD 3.0 score with albumin was significantly better in predicting the short-term prognosis of East Asian patients on the LT waitlist than the current allocation system, original MELD.

Six-Minute walk distance predicts outcomes in liver transplant candidates

A 6-minute walk test is a simple tool for assessing submaximal exercise capacity. We sought to determine whether a 6-minute walk distance (6MWD) predicts outcomes in patients with cirrhosis. The Pulmonary Vascular Complications of Liver Disease 2 study is a multicenter, prospective cohort study that enrolled adults with portal hypertension during liver transplantation evaluation. We excluded subjects with an incident or prevalent portopulmonary hypertension. The 6-minute walk test was performed using standardized methods. Cox proportional hazards modeling and multivariable linear regression analysis were performed to determine the relationship between baseline 6MWD and outcomes. The study sample included 352 subjects. The mean 6MWD was 391±101 m. For each 50-meter decrease in 6MWD, there was a 25% increase in the risk of death (HR 1.25, 95% CI [1.11, 1.41], p < 0.001) after adjustment for age, gender, body mass index, MELD-Na, and liver transplant as a time-varying covariate. In a multistate model, each 50-meter decrease in 6MWD was associated with an increased risk of death before the liver transplant ( p < 0.001) but not after the transplant. 6MWD was similar to MELD-Na in discriminating mortality. Each 50-meter decrease in 6MWD was associated with an increase in all-cause ( p < 0.001) and transplant-free hospitalizations ( p < 0.001) in multivariable models for time-to-recurrent events. Shorter 6MWD was associated with worse Short Form-36 physical ( p < 0.001) and mental component scores ( p = 0.05). In conclusion, shorter 6MWD is associated with an increased risk of death, hospitalizations, and worse quality of life in patients evaluated for liver transplantation. The 6-minute walk distance may be a useful adjunct for risk assessment in patients undergoing liver transplant evaluation.

Hyperspectral Imaging for Viability Assessment of Human Liver Allografts During Normothermic Machine Perfusion

Normothermic machine perfusion (NMP) is nowadays frequently utilized in liver transplantation. Despite commonly accepted viability assessment criteria, such as perfusate lactate and perfusate pH, there is a lack of predictive organ evaluation strategies to ensure graft viability. Hyperspectral imaging (HSI)-as an optical imaging modality increasingly applied in the biomedical field-might provide additional useful data regarding allograft viability and performance of liver grafts during NMP.

METHODS

Twenty-five deceased donor liver allografts were included in the study. During NMP, graft viability was assessed conventionally and by means of HSI. Images of liver parenchyma were acquired at 1, 2, and 4 h of NMP, and subsequently analyzed using a specialized HSI acquisition software to compute oxygen saturation, tissue hemoglobin index, near-infrared perfusion index, and tissue water index. To analyze the association between HSI parameters and perfusate lactate as well as perfusate pH, we performed simple linear regression analysis.

RESULTS

Perfusate lactate at 1, 2, and 4 h NMP was 1.5 [0.3-8.1], 0.9 [0.3-2.8], and 0.9 [0.1-2.2] mmol/L. Perfusate pH at 1, 2, and 4 h NMP was 7.329 [7.013-7.510], 7.318 [7.081-7.472], and 7.265 [6.967-7.462], respectively. Oxygen saturation predicted perfusate lactate at 1 and 2 h NMP (R² = 0.1577, P = 0.0493; R² = 0.1831, P = 0.0329; respectively). Tissue hemoglobin index predicted perfusate lactate at 1, 2, and 4 h NMP (R² = 0.1916, P = 0.0286; R² = 0.2900, P = 0.0055; R² = 0.2453, P = 0.0139; respectively).

CONCLUSIONS

HSI may serve as a noninvasive tool for viability assessment during NMP. Further evaluation and validation of HSI parameters are warranted in larger sample sizes.

Introducing Incentives and Reducing Disincentives in Enhancing Deceased Organ Donation and Transplantation

Despite the effectiveness of solid organ transplantation, progress to close the gap between donor organs and demand remains slow. An organ shortage increases the waiting time for transplant and involves significant costs including patient morbidity and mortality. Against the background of a low deceased organ donation rate, this article discusses the option of introducing incentives and removing disincentives to deceased organ donation. Perspectives from ethics, general public opinion, and the health care profession are examined to ensure a comprehensive appraisal and illustrate different facets of opinion on this complex area. Special cultural and psychosocial considerations in Asia, including the family based consent model, are discussed.

Alcoholic liver disease: a new insight into the pathogenesis of liver disease

Excessive alcohol consumption contributes to a broad clinical spectrum of liver diseases, from simple steatosis to end-stage hepatocellular carcinoma. The liver is the primary organ that metabolizes ingested alcohol and is exquisitely sensitive to alcohol intake. Alcohol metabolism is classified into two pathways: oxidative and non-oxidative alcohol metabolism. Both oxidative and non-oxidative alcohol metabolisms and their metabolites have toxic consequences for multiple organs, including the liver, adipose tissue, intestine, and pancreas. Although many studies have focused on the effects of oxidative alcohol metabolites on liver damage, the importance of non-oxidative alcohol metabolites in cellular damage has also been discovered. Furthermore, extrahepatic alcohol effects are crucial for providing additional information necessary for the progression of alcoholic liver disease. Therefore, studying the effects of alcohol-producing metabolites and interorgan crosstalk between the liver and peripheral organs that express ethanol-metabolizing enzymes will facilitate a comprehensive understanding of the pathogenesis of alcoholic liver disease. This review focuses on alcohol-metabolite-associated hepatotoxicity due to oxidative and non-oxidative alcohol metabolites and the role of interorgan crosstalk in alcoholic liver disease pathogenesis.

Single Center Experience with Incidence, Impact and Predictors of Biliary Complications in Donation After Circulatory Death Liver Transplantation

Introduction: Utilizing allografts from donors after cardiac death (DCD) has improved organ availability, and DCD livers comprise a growing proportion of transplantations. However, it has been suggested that DCD transplantations have worse outcomes. Research Questions: We aimed to characterize outcomes in a large cohort of DCD transplantations, identify trends in outcomes over time, and identify factors associated with the development of biliary complications. Design: We conducted an observational retrospective cohort study of patients receiving DCD liver allografts within a large academic teaching hospital with a high transplantation volume. Consecutive patients who underwent Type III DCD liver transplantation from 2006-2016 were included in our cohort. Re-transplantations and multi-organ transplant recipients were excluded. Results: Ninety-six type III DCD transplantations occurred between 2006-2016. We report a 1one-year patient survival of 90.6% (87) and a 5five-year patient survival of 69.8% (67). Twenty-nine (30.2%) patients experienced any biliary complication in the first year following discharge, with 17 (17.7%) experiencing ischemic cholangiopathy. Five-year patient (P = 0.04) and graft (P = 0.005) survival improved over time. Post-operative biliary complications experienced during index admission and prior to discharge were found to be associated with the development of biliary complications (P = 0.005) and ischemic cholangiopathy (P = 0.01) following discharge. Conclusion: Our data suggested that outcomes using DCD allografts have improved, however biliary complications remain a significant issue in DCD transplantation. Patients who experienced post-operative biliary complications during index admission may require more frequent screening to allow the initiation of earlier treatment for biliary complications.

Evaluation of equine xenogeneic mixed lymphocyte reactions using 5-ethynyl-2'-deoxyuridine (EdU)

Allogeneic solid organ transplantation is currently the only treatment option for end stage organ disease. The shortage of available donor organs has driven efforts to utilize xenogeneic organs for transplantation. In vitro methods for evaluating immune-compatibility are a quick and low cost means of screening novel tissue products prior to more involved, expensive, and invasive live animal studies. Recently, a new analog of the DNA base thymidine, 5-ethynyl-2'-deoxyuridine (EdU), was developed. It may be used in a fast, efficient and specific means of evaluating cell proliferation via flow cytometry. This study was designed to test and optimize this platform for assessing equine xenogeneic one-way mixed lymphocyte reaction (MLR) to porcine stimulator cells. Furthermore, it was hypothesized that an enriched T-lymphocyte (T-cell) population would generate a stronger proliferative response to stimulation, and higher levels of cytokine production when compared to unfractionated peripheral blood mononuclear cells (PBMCs). PBMCs and T-cells were isolated from 3 horses and 4 pigs. Equine xenogeneic MLRs were set up using porcine allogeneic MLRs as a reference for clinically acceptable levels of cell proliferation. Equine T-cells showed significantly greater EdU incorporation in one-way xenogeneic MLRs than equine PBMCs. However, there was no significant difference in cell proliferation between porcine T-cell and PBMC as responders in allogenic one-way MLRs. Given the results of this study, we consider that enriched equine T-cells should be used in preference to unfractionated PBMCs when attempting to evaluate the equine xenogeneic response using the EdU assay as an indicator of suitability for transplant in vivo.

Liver Transplant Center Size and The Impact on the Clinical Outcomes and Resource Utilization

BACKGROUND

Prior studies suggest that transplant center volume is associated with liver transplantation (LT) outcomes. We compared patient characteristics and waitlist outcomes among transplant centers in the U.S. with different volumes.

METHODS

Data for adult waitlisted candidates and LT recipients in the U.S. between 2008 and 2017 were extracted from the Scientific Registry of Transplant Recipients database. Transplant centers were categorized by transplants/year into tertiles:low-volume centers (LVCs; <20 transplantations per year)medium-volume centers (MVCs; 20-55 transplantations per year)high-volume centers (HVCs; >55 transplantations per year)Patient characteristics, waitlist outcomes, and factors associated with post-transplantation mortality were compared.

RESULTS

From 141 centers, 112,110 patients were waitlisted for LT: 6% at LVCs, 26% at MVCs, and 68% at HVCs. Patients listed in LVCs were less likely to have private insurance but had higher Medicaid and Veterans Affairs healthcare rates. Patients at LVCs were less likely to receive LT (47% vs. 53% in MVC vs. 61% in HVC), had higher transfer rates to other centers, and were more likely to be removed from the waitlist. In competing risk survival analysis, adjusted for center location, MELD score, and clinico-demographic factors, patients listed at an HVC were more likely to receive LT (aHR:1.30; 95%CI= 1.27-1.33; P<0.001). Among LT-recipients (n=62,131), receiving a transplant at an LVC was associated with higher post-LT mortality (aHR:1.16; 95%CI=1.05-1.28; P=0.003).

CONCLUSION

Patients in LVCs were less likely to receive a LT and a higher risk of post-LT death.Supplemental Visual Abstract; http://links.lww.com/TP/C274.

HBV-infection rate and long-term outcome after liver-transplantation of anti-HBc-positive liver-grafts to HBV-naïve recipients: A retrospective study

BACKGROUND

Anti-HBc only positive liver grafts may be suitable for HBV-naive recipients insofar as an appropriate infection prophylaxis is performed. Therefore, we investigated the effect of prophylactic regimens on HBV infection prevention and long-term outcome of anti-HBc-positive graft recipients.

PATIENTS AND METHODS

This retrospective monocenter study consisted of a cohort of 1912 patients who underwent deceased donor liver transplantation at our transplant center between June 1987 and July 2019. 81 HBV-naïve patients after reception of an anti-HBc-positive liver-graft and consecutive HBV prophylaxis were selected for further examination. HBV infection rate and host- and graft-survival rates were compared to a matched control group consisting of 162 HBV-naïve patients after reception of anti-HBc-negative grafts. Pharmaceutical HBV prophylaxis included: only HBIG, only NUCs, or combined HBIG and NUCs.

RESULTS

Compared to control cases of HBV-naïve anti-HBc-negative graft recipients, no differences in host- and graft-survival rate were determined.13 of 81 anti-HBc-positive graft recipients (16%) developed HBV-infection after liver transplantation. No patient suffered from HBV infection after receiving modern NUCs. Survival analysis showed no statistical differences between patients with and without infection concerning host- and graft-survival.

CONCLUSION

Especially in times of organ shortage, anti-HBc-positive liver grafts may be useful for liver transplantation in HBV-naïve recipients. Efficient prophylactic regimens can prevent HBV-infection.

Organ donation in the US and Europe: The supply vs demand imbalance

Organ donation and transplantation remain the best and most cost-effective clinical solution for end-stage organ failure. Several agencies across the US and Europe provide legislative, regulatory, and humanitarian services to generate smoother applications in all transplantation processes and donor-recipient relationships. US and European statistics present nine types of grafts, with kidneys being the most transplanted organ worldwide. However, organ shortage, religion, underrepresented minority groups, difficulties in obtaining consent, lack of understanding, and general ethical concerns present challenging barriers to organ donation, reflecting the complexity of graft procurement and allocation. Breaking down these barriers to reduce the organ-supply imbalance requires an appropriate multifaceted approach. Some of the key areas include increasing the potential donor pool and consent rates, apt organ allocation, and improving organ health. Additionally, suitable policies and standardized guidelines for both donors and recipients, alongside educational initiatives, are needed to ensure patient safety and global awareness. Looking forward, novel and effective research plans and initiatives are needed if we are to avoid a colossal supply-demand gap.

Acute-on-chronic liver failure: to admit to intensive care or not?

Acute-on-chronic liver failure is used to describe an acute decline in liver function in a patient with existing liver disease combined with other organ failure. Acute-on-chronic liver failure is associated with high short-term mortality, and the greater the number and severity of organ failures, the higher the mortality. The most commonly identified precipitants of acute-on-chronic liver failure include bacterial infection, gastrointestinal haemorrhage, viral hepatitis and recent excessive alcohol intake. Since some of these aetiologies are treatable, organ failure may return to pre-decompensation levels in up to 55% of patients. As a result, a trial of critical care treatment may be appropriate for many of these patients. Clinical scoring tools may help clinicians recognise futility, allowing timely withdrawal of organ support and shifting the focus of care toward palliation.

Effect of COVID-19 on liver transplantation in Korea

COVID-19 is now a pandemic with increasing numbers of cases and deaths. In addition to the economic and social damage caused by COVID-19 outbreak prolongation, damage caused by delayed treatment of other diseases such as severe cirrhosis is also serious. We aimed to describe the effect of COVID-19 on the number of liver transplants (LT) in South Korea. The number of LT performed in Korea during the Middle East Respiratory Syndrome (MERS) outbreak, and the COVID-19 pandemic was compared with the average number of LT performed in the past 5 years. There were 108.5 cases of LT performed per month during the MERS outbreak. It was 11% lower than the average of 122.8 cases per month for the last 5 years. LDLT and DDLT decreased by 13% to 75.3 cases and by 7.5% to 33.2 cases per month during the MERS epidemic, respectively. From January to March 2020 (COVID-19 outbreak), the number of LT did not decrease significantly. The lockdown caused by COVID-19 did not affect the number of liver transplants in Korea. Establishing a safe process and procedure of liver transplantation within safe boundaries can be beneficial in reducing the side effects of lockdown and saving patients' lives.

The effects of microgravity on differentiation and cell growth in stem cells and cancer stem cells

A spaceflight has enormous influence on the health of space voyagers due to the combined effects of microgravity and cosmic radiation. Known effects of microgravity (μg) on cells are changes in differentiation and growth. Considering the commercialization of spaceflight, future space exploration, and long-term manned flights, research focusing on differentiation and growth of stem cells and cancer cells exposed to real (r-) and simulated (s-) μg is of high interest for regenerative medicine and cancer research. In this review, we focus on platforms to study r- and s-μg as well as the impact of μg on cancer stem cells in the field of gastrointestinal cancer, lung cancer, and osteosarcoma. Moreover, we review the current knowledge of different types of stem cells exposed to μg conditions with regard to differentiation and engineering of cartilage, bone, vasculature, heart, skin, and liver constructs.

Donación de órganos y trasplante en la era COVID-19: ¿Realmente se deben parar los programas?

Durante los primeros meses de la pandemia por SARS-CoV2 (Coronavirus 2 del Síndrome Respiratorio Agudo y Grave), el agente etiológico de la Enfermedad Infecciosa por Coronavirus de 2019 (COVID-19), la actividad de donación y trasplante de órganos en todo el mundo se ha visto claramente afectada. Las principales razones que en este momento motivan el cese parcial o total de los trasplantes son: 1) la carga asistencial que genera el manejo de un potencial donante en la Unidad de Cuidado Intensivo (UCI), 2) el alto riesgo de contagio entre donante y receptor, 3) el riesgo de inmunosuprimir a un paciente en medio de la pandemia y 4) la escases de camas de UCI. A pesar de que el mundo está enfrentando a una enfermedad emergente que merece especial atención, al mismo tiempo continúan prevaleciendo las complicaciones asociadas a las demás enfermedades incluyendo las complicaciones de patologías crónicas en estado terminal. La decisión de continuar con los programas de trasplante se debe basar en el comportamiento local del virus y en la capacidad asistencial de cada una de las instituciones. En Colombia, el comportamiento epidemiológico del SARS-CoV2 varía significativamente entre las diferentes regionales, permitiendo a las instituciones que hasta el momento, presentan poca carga de atención del COVID-19 retomar sus actividades de trasplante. De esta manera se propone un balance entre mantener las medidas de prevención y atención del COVID-19 y continuar ofreciendo los servicios de trasplante, principalmente a los pacientes con alto riesgo de morbi-mortalidad en lista de espera.