Bacteria have been genetically engineered to enter and live inside mouse immune cells, where they released proteins that altered the behaviour of those cells. The work is a first step towards creating “artificial endosymbionts” that could live inside some human body cells and do everything from guiding the regeneration of damaged tissues to treating cancer.

Jesus Christ.

Genetic engineering is like a pajeet trying to re-engineer a computer system with malware. We don't know all the ramifications of what these modified things will do, because we don't understand the system thoroughly. Even just drugs in the human body cause all sorts of side-effects. Genes are on a whole other level.