Researchers have now taken a step toward that vision of molecular systems that repair cells inside the human body. Molecular repair built from a patient's own cells will eventually ferret out cancer, repair injured tissue, and even remove plaque from blood vessels.

They have gotten tracheal cells to form coordinated groups called organoids that can propel themselves with tiny appendages. When added to wounded neurons in the lab, these anthrobots helped neurons repair themselves.

These organoids can help with monitoring inside the body, delivering drugs and improving repair at the cellular level. These are living versions of the vision of nanobots. Advanced versions of these systems could accelerate healing of neurons, nerves and the spinal cord and many other tissues. The neuron, nerve and spinal cord repair would be critical for the brain repair, brain swapping and new body growth proposal for a form of immortality.

Michael Levin, a developmental biologist at Tufts University and leader of the new study, made his first living robots 4 years ago. He and his colleagues stitched together embryonic heart and skin cells from the African clawed frog to create an organoid with cilia, tiny hairs that move back and forth, enabling it to crawl and even swim. Levin demonstrated that cells can be coached to do something they would never have done on their own.

In the new study, Levin's graduate student, Gizem Gumuskaya, started with cells that line the adult human trachea. These cells also sport cilia, and the researchers hoped to harness the appendages as tiny oars to power and move the organoid.

Gumuskaya put individual tracheal cells in a 3D scaffolding, made from rat tissue, which resembles the environment in the human trachea. After 2 weeks, the cells multiplied and formed tiny spheres, but their cilia were inside these spheres and thus useless for locomotion. So the researchers immersed the cells in a special bath, whose liquid properties prompted them to turn their cilia out.