Ex vivo (Latin for 'out of the living') refers to biological studies involving tissues, organs, or cells maintained outside their native organism under controlled laboratory conditions. By carefully managing factors such as temperature, oxygenation, nutrient delivery, and perfusing a nutrient solution through the tissue's vasculature, researchers sustain function long enough to conduct experiments that would be difficult or unethical in a living body. Ex vivo models occupy a middle ground between in vitro (lit. 'in the glass') models, which typically use isolated cells, and in vivo (lit. 'in the living') studies conducted inside living organisms.
Ex vivo platforms support pharmacologic screening, toxicology testing, transplant evaluation, developmental biology, and investigations of disease-mechanism research across medicine and biology, from cardiology and neuroscience to dermatology and orthopedics. Because they often use human tissues obtained from clinical procedures or biobanks, they can reduce reliance on live-animal experimentation; their utility, however, is limited by finite viability, incomplete systemic integration, and post-mortem biochemical changes that accumulate over time. The earliest perfusion studies were conducted in the mid-19th century, and subsequent advances in sterilization, imaging, and microfluidics have facilitated broader adoption into the 20th and 21st centuries. Regulatory oversight depends on specimen origin: human ex vivo research is subject to informed consent, whereas animal-derived models fall under institutional animal care guidelines.
