Developing embryos reveal earliest immune response yet

The earliest signs of an innate immune response have been identified in embryos, shedding light on why some fail to form properly during early development.

As reported last week in Nature, early embryos, lacking specialised immune cells, are particularly prone to cellular defects which can lead to developmental failures. Researchers at the Centre for Genomic Regulation in Barcelona, Spain, found that cells in the embryo's epithelium, the first tissue to form during vertebrate development, are able to clear surrounding dead cells, thereby increasing chances of survival, in a process known as 'epithelial phagocytosis'.

'Long before the formation of the organs, one of the first tasks performed by a developing embryo is to create a protective tissue' said Dr Esteban Hoijman, lead author of the study. He added, 'like people distributing food around the dining table before tucking into their meal, we found that epithelial cells push defective cells towards other epithelial cells, speeding up the removal of dying cells.'

The research was conducted using high-resolution time-lapse imaging technology to observe zebrafish and mouse embryos, two widely used model organisms for developmental research. This technique enabled the researchers to both see and quantify the process of defective cells being removed within the embryos.

'Here we propose a new evolutionarily conserved function for epithelia as efficient scavengers of dying cells in the earliest stages of vertebrate embryogenesis' said Dr Verena Ruprecht, who led the project.

The findings of this research may have significant implications for treating infertility and early miscarriages. Dr Ruprecht added, 'Our work may have important clinical applications by one day leading to improved screening methods and embryo quality assessment standards used in fertility clinics.'

The authors have suggested that future work will focus on applying these findings to treat infertility, as well as further study of how cells and tissues cooperate as part of other biological processes.