Scientists from Northwestern University in Chicago have revealed that the process of producing red blood cells in the human body occurs in a completely different way than previously thought, overturning scientific assumptions that persisted for decades and were mostly based on animal research.

The study was led by Dr. Bing Ji from the Feinberg School of Medicine, whose team used advanced microscopic techniques to directly observe what are known as 'red blood cell islands,' structures long believed to act as 'incubators' where these cells mature.

Ji said in a statement: 'For decades, our understanding of these structures was derived almost entirely from studies on mice. Most experiments relied on isolating cells and studying them in flat two-dimensional systems, which disrupted their natural organization.'

In this study, the researchers were able to preserve the natural structure of 'red blood cell islands' while directly comparing mouse and human samples. The mouse results were as expected: the islands formed around a specialized phagocyte carrying the protein C1Q, located at the center of clusters of developing red blood cells and contributing to the removal of damaged cell debris.

However, the surprise came from the human results: it turned out that there is no similar regulatory center in the human body.

Ji explained: 'In humans, red blood cells aggregate on their own without the need for a central phagocyte. This overturns a long-standing assumption that human blood formation mirrors what we see in mice.'

In their report published in the journal Science, the researchers described the discovery as a 'radical shift' in understanding how the body produces its most abundant cells, noting that a large part of biomedical research relies on mouse models, and that differences in the fundamental biological system affect the interpretation of disease mechanisms and the development of treatments.

The results raise new questions about how the human body compensates for the absence of central phagocytes, especially since these cells play a crucial role in mice in removing expelled nuclei during red blood cell maturation. Ji emphasized that future research will focus on answering this and other questions.