Without genetic modification, scientists have created a new robotlike organism called a ‘xenobot’ from the stem cells of a frog.
Stem cells are basal, unspecialized structures. They do not have a particular purpose in the body prior to maturation, yet their utility is diverse. A stem cell can develop into one of numerous cellular archetypes: muscle cells, blood cells, nerve cells and various others. These specialized cells have clear and essential capabilities needed for the organism to function.
Harvesting stem cells from the embryo of an African clawed frog, researchers from Harvard University, the University of Vermont, and Tufts University formed piles of cellular material and allowed them to grow. Cilia, or quivering hairlike filaments, would emerge on the clumps and spark movement as they disturbed its surrounding solution. This caused the stem cells to swim in swirling patterns.
While spiraling, these cellular configurations occasionally picked up free floating stem cells in their paths. With the original spherical nature of these xenobots, this event was quite uncommon. The researchers circumvented this issue, using an evolutionary algorithm to hypothesize an ideal shape for the xenobots. An evolutionary algorithm is a subset of artificial intelligence with an emphasis on replicating the behaviors of living things.
Their computations indicated that organizing the stem cells in a crescent would allow them to optimally pick up isolated stem cells. By manually shaping the stem cells of the xenobots, researchers effectively ‘programmed’ them. None of the cells’ genetics were altered, but their relative positionings led to specific emergent behaviors desired by the scientists.
When enough stem cells were collected by the spiraling structures, they would separate into their own pile and follow a similar life cycle: grow cilia, start spiraling, collect more stem cells. Of course, these new piles lacked the refined crescent of the researchers’ hand-made variations, but could still slowly execute the same tasks. They were duplicating themselves in a process known as kinematic self-replication.
By ‘programming’ the frog cells in an alternative manner, the xenobots can perform completely different tasks. Scientists hope that they might function as nanobots, doing things such as delivering drugs to specific parts of the human body. This would be a particularly powerful application as the ‘robots’ are completely organic and biodegradable, implying they would have a lessened negative impact on the patient.
Between its programmability and self-replicative capabilities, a xenobot stands at the intersection between robotics and biology. These ‘living robots’ may lead to revolutionary advancements in medicine along with other fields.