Dear readers,

The sad news of the passing of Marty Stephens brings home that while looking forward to the exciting future of the 3Rs field, we should also take time to reflect on its history and the people who have shaped it. This issue contains a report by Michael Balls et al. on the 60 Years of 3Rs symposium with an extensive table documenting the main developments in the 3Rs field by year, and reflections on the many milestones and how they were reached by the people who made it all happen. Inspired by these trailblazing contributions, the Centers for Alternatives to Animal Testing, CAAT and CAAT-Europe, together with ALTEX announce the establishment of the 3Rs Hall of Honor to celebrate the pioneers in the 3Rs field.

In conjunction with DNT-5, this issue’s Food for Thought … contribution by Lena Smirnova and colleagues looks back on the progress in establishing non-animal methods for developmental neurotoxicity testing over the past two decades leading to last year’s OECD guidance on the interpretation of the battery of in vitro DNT tests. The article also explores the potential of current technological advances to drive the field further toward a better understanding of the hazards of chemical exposure to human brain development.

Aina Mogas Barcons et al. introduce a model of spinal cord injury using slices of spinal cord tissue from chick embryos aiming to partially replace live adult animal testing. Improvements of repair mechanisms in injured sections, such as outgrowth of nerve cells and activity of immune cells, after implantation of a novel scaffold could be demonstrated.

Steven Kunnen et al. analyze transcriptomics gene co-expression networks to identify the mechanisms associated with exposure of primary hepatocytes and HepaRG cells to known liver toxicants and to derive benchmark concentrations. The approach can inform adverse outcome pathways and chemical risk assessment without the use of animals.

Adverse outcome pathways seek to collate and structure information on the toxic effects of chemicals. This concept has been expanded to include non-chemical stressors such as nanomaterials, radiation, viruses, biological therapeutic material, and microorganisms used as pesticides, which can trigger the same key events and adverse outcomes as chemicals. Laure-Alix Clerbaux and colleagues explain the challenges and benefits of accommodating these stressors in the system.

Tom Roos and colleagues describe their protocol to conduct a systematic mapping review of studies on the effects of pollutants on human heart disease that aims to collate a comprehensive database on available evidence for 129 chemicals including heavy metals, air pollutants, and pesticides to contribute to the development of non-animal testing methods.

Calls to plan the phase-out of animal experimentation from governments, parliaments, and non-governmental organizations have brought this discussion into the political arena and incited some ardent opposition. Nico Müller pulls together ten central documents to distill what is meant by the phrase, and what measures, milestones, and monitoring are needed to advance a constructive discussion. The article elegantly contrasts charitable versus uncharitable interpretations of the documents and formulates the central moral argument as well as seven action points.

The t⁴ Workshop Report by Alexandra Maertens et al. discusses the path towards implementing an artificial intelligence-based probabilistic risk assessment in toxicology. This approach will provide a deeper understanding of the risks of chemicals to human health and the environment.

The t⁴ Workshop Report by Emily Golden et al. brings forward the discussion on using virtual control groups to replace animal controls in pharmaceutical safety studies by describing an industry initiative to collect and curate existing data, to identify and assess suitable matching criteria to build virtual control groups, and to qualify the approach.

Safety testing seeks to identify any relevant hazard of a chemical on the organism. Walter Zobl et al. challenge the limits of a cell-based test battery representing cells from various sensitive organs by testing a set of chemicals known to cause effects in organs not represented in the battery. Most compounds did cause effects that translated to protective thresholds, and those that did not indicate that the approach can be improved further by adding an assay that captures hematotoxicity.

Meeting Reports, including one on designing a qualification framework for organ-on-chip approaches, and the Corners update you with further developments. The dates for the MPS World Summit, the EUSAAT Congress, and the 13^th World Congress as well as other events can be found on the ALTEX website.

Hoping you are inspired by this exciting issue of ALTEX,

Sonja von Aulock
Editor-in-chief

Martin “Marty” L. Stephens, PhD, a thought leader in the field of humane science and animal alternatives, passed away at his home in Clarksburg, MD, on February 17, 2024. Throughout his esteemed career, Marty dedicated himself to the advancement of alternatives across research, education, and safety testing. His professional positions included Vice President of Animal Research Issues for the Humane Society of the United States, Founding Director of the Evidence-Based Toxicology Collaboration (EBTC), and Senior Research Associate at the Center for Alternatives to Animal Testing (CAAT) at the Johns Hopkins Bloomberg School of Public Health. Outside of his professional roles, Marty Stephens was widely known for being a remarkably kind, committed, and curious person.

Marty’s worked extended well beyond scientific study to include legislation and animal advocacy initiatives. He played a crucial role in the National Research Council committee, driving governmental initiatives aimed at reducing the use of animals in toxicity testing and making instrumental contributions to the uptake and advancement of non-animal testing methodologies. Marty was not only a gifted scientist but also a skilled diplomat able to bring together scientists, activists, academics, and industry professionals to effect positive change in the pursuit of more humane science.

Among his many achievements, the Russell and Burch Award in 2014, which honored a lifelong commitment to advancing the 3Rs, specifically targeting industry and regulatory acceptance, stands out. Interestingly, Marty was the creator of this award and personally traveled to the United Kingdom to meet The Principles of Humane Experimental Technique authors William Russell and Rex Burch and request their permission to name the award after them. In doing so, he not only reconnected these two colleagues, who had lost touch, but introduced them to the profound impact their early work had had and prompted their enthusiastic engagement with the passionate community that had grown out of their seminal text.

Marty’s impact extends well beyond his professional achievements; he was a beloved figure in the field, admired for his gentle nature and unwavering commitment to the welfare of both humans and animals. An avid hiker, kayaker, biker, and birdwatcher, Marty found joy in the natural world he worked so tirelessly to protect.

As we mourn the loss of Marty Stephens, we also celebrate his extraordinary life and legacy. His work has undoubtably laid the foundation for more humane approaches in scientific research to flourish. Marty’s spirit, passion, and unyielding commitment to this cause will certainly continue to inspire those who choose to dedicate themselves to advancing a more humane world.

Marty will be remembered in a virtual seminar on April 17; see CAATfeed in this issue for more information. Marty will be honored as one of the first inductees into the newly created Hall of Honor announced in this issue of ALTEX. The Evidence-Based Toxicology Collaboration (EBTC) has announced it will dedicate a new award to the memory of Marty, see CAATfeed in this issue.