Why the Synthetic Cell Needs Democratic Governance.

Engineering synthetic cells from the bottom up is expected to revolutionize biotechnology. How can synthetic cells support societal transitions necessary to tackle our current global challenges in a socially equitable and sustainable manner? To answer this question, we need to assess socioeconomic considerations and engage in early constructive public dialogue.

The unique status of first-in-human studies: strengthening the social value requirement.

For clinical research to be ethical, risks need to be balanced by anticipated benefits. This is challenging for first-in-human (FIH) studies as participants are not expected to benefit directly, and risks are potentially high. We argue that this differentiates FIH studies from other clinical trials to the extent that they should be given unique status in international research ethics guidelines. As there is a general positive attitude regarding the benefits of science, it is important to establish a more systematic method to assess anticipated social value to safeguard participants not only from enrolling in risky, but also in futile trials. Here, we provide some of necessary steps needed to assess the anticipated social value of the intervention.

Studying the lay of the land: views and experiences of professionals in the translational pluripotent stem cell field.

AIM: The inherent uncertainty of first-in-human trials, combined with the technical complexity of pluripotent stem cells (PSCs), makes early phase PSC studies ethically challenging. Conducting parallel bioethics research based on experiences and views of professionals in the stem cell field is therefore important. MATERIALS & METHODS: We conducted semistructured interviews with various stakeholders to get a lay of the land of ethical issues professionals find relevant to the translation of PSCs. RESULTS: We identified four themes in the interviews: the uniqueness of PSCs, the suitability of the current research paradigm, the justification for early phase PSC studies and the involvement of patients and research participants. CONCLUSION: We conclude that a debate should take place discussing the suitability of the current research paradigm for translational PSC studies.

Participant selection for preventive Regenerative Medicine trials: ethical challenges of selecting individuals at risk.

The innovative field of Regenerative Medicine (RM) is expected to extend the possibilities of prevention or early treatment in healthcare. Increasingly, clinical trials will be developed for people at risk of disease to investigate these RM interventions. These individuals at risk are characterised by their susceptibility for developing clinically manifest disease in future due to the existence of degenerative abnormalities. So far, there has been little debate about the ethical appropriateness of including such individuals at risk in clinical trials. We discuss three main challenges of selecting this participant model for testing RM interventions: the challenge of achieving a proportional risk-benefit balance; complexities in the trial design in terms of follow-up and sample size; and the difficulty of obtaining informed consent due to the many uncertainties. We conclude that selecting the model is not ethically justifiable for first-in-man trials with RM interventions due to the high risks and uncertainties. However, the model can be ethically appropriate for testing the efficacy of RM interventions under the following conditions: interventions should be low risk; the degenerative abnormalities (and other risk factors) should be strongly related with disease within a short time frame; robust preclinical evidence of efficacy needs to be present; and the informed consent procedure should contain extra safeguards with regard to communication on uncertainties.

The social value of clinical research.

BACKGROUND: International documents on ethical conduct in clinical research have in common the principle that potential harms to research participants must be proportional to anticipated benefits. The anticipated benefits that can justify human research consist of direct benefits to the research participant, and societal benefits, also called social value. In first-in-human research, no direct benefits are expected and the benefit component of the risks-benefit assessment thus merely exists in social value. The concept social value is ambiguous by nature and is used in numerous ways in the research ethics literature. Because social value justifies involving human participants, especially in early human trials, this is problematic. DISCUSSION: Our analysis and interpretation of the concept social value has led to three proposals. First, as no direct benefits are expected for the research participants in first-in-human trials, we believe it is better to discuss a risk- value assessment instead of a risk - benefit assessment. This will also make explicit the necessity to have a clear and common use for the concept social value. Second, to avoid confusion we propose to limit the concept social value to the intervention tested. It is the expected improvement the intervention can bring to the wellbeing of (future) patients or society that is referred to when we speak about social value. For the sole purpose of gaining knowledge, we should not expose humans to potential harm; the ultimate justification of involving humans in research lies in the anticipated social value of the intervention. Third, at the moment only the validity of the clinical research proposal is a prerequisite for research to take place. We recommend making the anticipated social value a prerequisite as well. SUMMARY: In this paper we analyze the use of the concept social value in research ethics. Despite its unavoidable ambiguity, we aim to find a best use of the concept, subject to its role in justifying involving humans in first-in-human research.

Variation in Streptococcus pneumoniae susceptibility to human antimicrobial peptides may mediate intraspecific competition.

Streptococcus pneumoniae is a facultative pathogen inhabiting the nasopharynx of humans where it is exposed to a range of antimicrobial peptides (AMPs) of the innate immune response. It is possible therefore that the susceptibility of strains to AMPs plays a role in determining their ability to colonize, and furthermore, that AMPs could mediate competitive interactions between co-colonizing genotypes. However, little is known about patterns of natural variation in AMP susceptibility of S. pneumoniae, and it is unclear whether the susceptibilities of an isolate to multiple human AMPs are correlated. We tested this by characterizing the susceptibility of 31 S. pneumoniae natural isolates to human neutrophil peptide (HNP-1) (α-defensin) and LL-37 (cathelicidin). We observed significant variation in susceptibility between isolates to both AMPs, and in the majority of isolates, susceptibilities to HNP-1 and LL-37 were uncorrelated. Clinical isolates were more susceptible to AMPs than were carriage isolates. The polysaccharide capsule of S. pneumoniae is thought to protect cells against AMPs. However, serotype alone could not explain the observed variation in susceptibility suggesting that genetic background plays an equally important role. We tested directly whether AMPs could mediate competition between isolates using competition experiments in the presence and absence of AMPs. These experiments demonstrated that AMPs could indeed reverse the outcome of competition between selected isolates. AMP-mediated competition could therefore contribute to the maintenance of intraspecific genetic diversity in S. pneumoniae.

Therapeutic antimicrobial peptides may compromise natural immunity.

Antimicrobial peptides (AMPs) have been proposed as a promising new class of antimicrobials despite warnings that therapeutic use could drive the evolution of pathogens resistant to our own immunity peptides. Using experimental evolution, we demonstrate that Staphylococcus aureus rapidly evolved resistance to pexiganan, a drug-candidate for diabetic leg ulcer infections. Evolved resistance was costly in terms of impaired growth rate, but costs-of-resistance were completely ameliorated by compensatory adaptation. Crucially, we show that, in some populations, experimentally evolved resistance to pexiganan provided S. aureus with cross-resistance to human-neutrophil-defensin-1, a key component of the innate immune response to infection. This unintended consequence of therapeutic use could drastically undermine our innate immune system's ability to control and clear microbial infections. Our results therefore highlight grave potential risks of AMP therapies, with implications for their development.

Ecological drivers of the evolution of public-goods cooperation in bacteria.

The role of ecological processes in the evolution of social traits is increasingly recognized. Here, we explore, using a general theoretical model and experiments with bacteria, the joint effects of disturbance frequency and resource supply on the evolution of cooperative biofilm formation. Our results demonstrate that cooperation tends to peak at intermediate frequencies of disturbance but that the peak shifts toward progressively higher frequencies of disturbance as resource supply increases. This appears to arise due to increased growth rates at higher levels of resource supply, which allows cooperators to more rapidly exceed the density threshold above which cooperation is beneficial following catastrophic disturbance. These findings demonstrate for the first time the importance of interactions between ecological processes in the evolution of public-goods cooperation and suggest that cooperation can be favored by selection across a wide range of ecological conditions.

Heterogeneous adaptive trajectories of small populations on complex fitness landscapes.

BACKGROUND: Small populations are thought to be adaptively handicapped, not only because they suffer more from deleterious mutations but also because they have limited access to new beneficial mutations, particularly those conferring large benefits. METHODOLOGY/PRINCIPAL FINDINGS: Here, we test this widely held conjecture using both simulations and experiments with small and large bacterial populations evolving in either a simple or a complex nutrient environment. Consistent with expectations, we find that small populations are adaptively constrained in the simple environment; however, in the complex environment small populations not only follow more heterogeneous adaptive trajectories, but can also attain higher fitness than the large populations. Large populations are constrained to near deterministic fixation of rare large-benefit mutations. While such determinism speeds adaptation on the smooth adaptive landscape represented by the simple environment, it can limit the ability of large populations from effectively exploring the underlying topography of rugged adaptive landscapes characterized by complex environments. CONCLUSIONS: Our results show that adaptive constraints often faced by small populations can be circumvented during evolution on rugged adaptive landscapes.

Spatial structure inhibits the rate of invasion of beneficial mutations in asexual populations.

Populations in spatially structured environments may be divided into a number of (semi-) isolated subpopulations due to limited offspring dispersal. Limited dispersal and, as a consequence, local competition could slow down the invasion of fitter mutants, allowing the short-term coexistence of ancestral genotypes and mutants. We determined the rate of invasion of beneficial mutants of Escherichia coli, dispersed to different degrees in a spatially structured environment during 40 generations, experimentally and theoretically. Simulations as well as experimental data show a decrease in the rate of invasion with increasingly constrained dispersal. When a beneficial mutant invades from a single spot, competition with the ancestral genotype takes place only along the edges of the growing colony patch. As the colony grows, the fitness of the mutant will decrease due to a decrease in the mutant's fraction that effectively competes with the surrounding ancestor. Despite its inherently higher competitive ability, increased intragenotype competition prevents the beneficial mutant from rapidly taking over, causing short-term coexistence of superior and inferior genotypes.

The effect of population structure on the adaptive radiation of microbial populations evolving in spatially structured environments.

Spatial structure is thought to be an important factor influencing the emergence and maintenance of genetic diversity. Previous studies have demonstrated that environmental heterogeneity, provided by spatial structure, leads to adaptive radiation of populations. In the present study, we investigate not only the impact of environmental heterogeneity on adaptive radiation, but also of population fragmentation and niche construction. Replicate populations founded by a single genotype of Escherichia coli were allowed to evolve for 900 generations by serial transfer in either a homogeneous environment, or a spatially structured environment that was either kept intact or destroyed with each daily transfer. Only populations evolving in the structured environment with intact population structure diversified: clones are significantly divergent in sugar catabolism, and show frequency-dependent fitness interactions indicative of stable coexistence. These findings demonstrate an important role for population fragmentation, a consequence of population structure in spatially structured environments, on the diversification of populations.