Xenotransplantation: public health risks--patient vs. society in an emerging field

Lebanese medical students' knowledge on and attitude toward xenotransplantation and its ethical issues: A cross-sectional study

INTRODUCTION

Xenotransplantation is the transplantation of animal parts into humans. This study's aim is to assess the Lebanese medical students' attitude toward xenotransplantation and their knowledge of its related ethical issues.

METHODS

A questionnaire was answered by 120 Lebanese medical students. Statistical analysis and ethical reflections were performed on the results.

RESULTS

Out of the 120 participants, 100 already knew about xenotransplantation, and 61.7% of the students believe that it is applied clinically. Only 25% trust that the animals need to be genetically modified for the organs to be eligible for transplantation. About 25.8% and 46.7% of the students, respectively, strongly agree that the patients' and physicians' beliefs play an important role in agreeing to the procedure. Students were likely to accept the animal organ for transplantation if the transplant could completely cure or improve the course of an untreatable disease (86.6% and 75.0%) or if the outcomes and risks were the same as with a human transplant with a shorter waiting period (71.7%). Students who agreed that animal rights and welfare/wellbeing should be respected tended to disagree with the statement that it is acceptable to use animals for human ends (p = .026).

CONCLUSION

Medical students proved to be knowledgeable on the ethical dilemmas related to xenotransplantation and showed a favorable attitude toward this procedure, which is crucial in its establishment as an absolute clinical reality in the near future and in the development and strengthening of research in this field.

How the COVID-19 pandemic may impact public support for clinical xenotransplantation in the United States?

Many patients who would undergo organ transplantation cannot proceed due to the inability of human organ donation to satisfy medical needs. Xenotransplantation has the potential to offer unlimited availability of pig organs for transplantation, and pig-to-non-human primate models have demonstrated outcomes that may soon justify clinical trials. However, one of the unique ethical challenges faced by xenotransplantation is that the risk of introducing potential zoonotic disease into the community must be weighed along with the benefit to the patient. While most experts believe that zoonosis is manageable, apprehension over disease transmission from animal donors to human recipients remains a frequent concern of many who are undecided or opposed to clinical xenotransplantation. The COVID-19 pandemic represents a scenario (rapid worldwide spread of a highly contagious novel zoonotic disease with no natural defense in humans) that would seem to justify apprehension, especially in the United States, which has largely avoided previous pandemic outbreaks. However, there are many differences between zoonosis found in the wild or after xenotransplantation that favor the safety of the latter. Still, these differences, as well as the benefits of xenotransplantation, are not widely understood outside of the field. We must therefore ask what impact the COVID-19 pandemic will have on attitudes toward xenotransplantation.

Ethical considerations in tissue engineering research: Case studies in translation

Tissue engineering research is a complex process that requires investigators to focus on the relationship between their research and anticipated gains in both knowledge and treatment improvements. The ethical considerations arising from tissue engineering research are similarly complex when addressing the translational progression from bench to bedside, and investigators in the field of tissue engineering act as moral agents at each step of their research along the translational pathway, from early benchwork and preclinical studies to clinical research. This review highlights the ethical considerations and challenges at each stage of research, by comparing issues surrounding two translational tissue engineering technologies: the bioartificial pancreas and a tissue engineered skeletal muscle construct. We present relevant ethical issues and questions to consider at each step along the translational pathway, from the basic science bench to preclinical research to first-in-human clinical trials. Topics at the bench level include maintaining data integrity, appropriate reporting and dissemination of results, and ensuring that studies are designed to yield results suitable for advancing research. Topics in preclinical research include the principle of "modest translational distance" and appropriate animal models. Topics in clinical research include key issues that arise in early-stage clinical trials, including selection of patient-subjects, disclosure of uncertainty, and defining success. The comparison of these two technologies and their ethical issues brings to light many challenges for translational tissue engineering research and provides guidance for investigators engaged in development of any tissue engineering technology.

Prevention, detection, and management of early bacterial and fungal infections in a preclinical cardiac xenotransplantation model that achieves prolonged survival

BACKGROUND

We analyzed bacterial and fungal infectious complications in a cohort of 16 consecutive experiments with the longest surviving cardiac xenografts to date.

METHODS

Transgenic, porcine-to-baboon, heterotopic (abdomen) cardiac xenotransplantation was performed in 16 consecutive experiments, using rapamycin, tacrolimus, corticosteroids, anti-CD20 monoclonal antibody, and an alpha-Gal-PEG polymer, as immunosuppression. Prophylactic anti-microbials included i.v. trimethoprim/sulfamethoxazole, oral ganciclovir/valganciclovir, and oral itraconazole. An episode of bacterial infection was defined as a positive blood and/or wound culture with: leukocytosis, fever >101.5 degrees F, and/or clinical deterioration.

RESULTS

Mean graft survival was 71 +/- 29 days; the longest was 113 days. There were 23 episodes of bacterial infection; 14 resolved with treatment. The mean time to the first episode of infection was 44 +/- 21 days (n=12). Eight of 16 deaths were due to infection: two bacterial-only, two cytomegalovirus (CMV) only, four both bacterial and CMV, and none fungal. The frequency of infection was 1, 2.8, and 1.8 episodes/100 survival days, respectively, for animals whose grafts survived for 30 to 59, 60 to 89, and >90 days. CMV infection (reviewed in detail in a separate communications) was due to baboon CMV, and was associated with low serum levels of ganciclovir.

CONCLUSION

In a cardiac xenograft model that achieved prolonged (>3 months) survival, bacteremia was common, but usually reversible, and fungal infection was prevented with prophylaxis. The level of immunosuppression required to achieve clinically meaningful xenograft survival is associated with a level of bacterial and fungal infectious complications that is manageable and similar to the early clinical experiences in human transplantation. Further research will determine if the viral infectious complications observed in these experiments can be reduced by optimizing blood levels of anti-viral prophylaxis and monitoring viral polymerase chain reaction levels.

Public opinion surveys about xenotransplantation

BACKGROUND

Xenotransplantation may eventually provide a solution to the worldwide shortage of human organs for transplantation. Xenotransplantation is surrounded by profound ethical issues, both for the potential recipients and for the society as a whole. Concurrent with increased scientific interest, there has been an increasing number of quantitative public opinion surveys conducted about xenotransplantation in the last decade. The aim of the present study was to elucidate these surveys, and to assess some factors that may affect the outcome of them.

MATERIALS AND METHODS

Surveys were identified by web and literature searches using key words in Medline and ISI Web of Knowledge. Reference lists of identified surveys were checked. Data was obtained from Inter-University Consortium for Political and Social Research (ICPSR) and directly from authors whose data were presented in another way than percentages. In total, the present material covered surveys from 35 sources, including 23 countries.

RESULTS AND DISCUSSION

Results showed that almost half of the respondents accept xenotransplantation, whereas the remaining half did either not accept or did not have/state an opinion. Over time, the proportions of acceptance seemed unchanged. The proportion of those who did not accept decreased and the remaining proportion increased. This pattern was evident in Europe and the US, but not in Japan. Gender and education were found to be associated with opinions to xenotransplantation. The influence of religion was not as straightforward. This may partly depend on how religiosity was measured in the polls. Wording of items influenced levels of acceptance. If a xenotransplant was the ''only choice'' proportions of acceptance increased, and if a ''risk for zoonotic diseases'' was stated proportions of acceptance decreased. When wording of survey items was somewhat comparable, there were often, but not always, minor differences in proportions of acceptance between surveys from different sources. Trends in opinions are best measured by the use of the same items. It is however difficult to phrase items that will not be affected by external events.

The challenge of emerging and re-emerging infectious diseases

Infectious diseases have for centuries ranked with wars and famine as major challenges to human progress and survival. They remain among the leading causes of death and disability worldwide. Against a constant background of established infections, epidemics of new and old infectious diseases periodically emerge, greatly magnifying the global burden of infections. Studies of these emerging infections reveal the evolutionary properties of pathogenic microorganisms and the dynamic relationships between microorganisms, their hosts and the environment.