It can’t eat or reproduce, but it is nonetheless alive: a team of Harvard scientists has created a living, moving stingray ‘robot’ using heart cells taken from rats. The ray can swim in the same manner as its biological counterparts and reacts to light. The team has published their results in Science and is already hailing their creation as a breakthrough for bioengineering.
In an interview with Popular Mechanics, head researcher Kit Parker says this new ray might represent a new class of hybrid life:
I think we’ve got a biological life-form here. A machine, but a biological life form. I wouldn’t call it an organism, because it can’t reproduce, but it certainly is alive.
Researchers can ‘control’ the stingray’s movement using light, a technique known as optogenetics. While the stingray responds to different amplitudes and positions of light, the scientists are in no way directly controlling the creepy “biohybrid;” it reacts on its own to the external stimulus:
Optogenetics allows for phototactic guidance, steering, and turning maneuvers. Optical stimulation induced sequential muscle activation via serpentine-patterned muscle circuits, leading to coordinated undulatory swimming. The speed and direction of the ray was controlled by modulating light frequency and by independently eliciting right and left fins, allowing the biohybrid machine to maneuver through an obstacle course.
The biohybrid stingray was constructed in layers. The uppermost layer was 3D printed from the same type of silicone used in breast implants, allowing for flexibility and translucency. The second layer, the stingray’s skeleton, is composed of gold, which has enough resistance to return to its original shape in between undulations of the ray’s wings. A third layer is flexible silicone like the first.
The last layer of the stingray’s body is where things get interesting. This layer is composed of genetically-engineered living cells taken from the heart muscles of rats. Like the muscles of the heart, these cells can undulate in rhythmic patterns when responding to stimulus, in this case being light. The cells were specially designed to only respond to particular wavelengths and frequencies of light selected by the ray’s designers.
By altering the position and frequency of the light shining upon the ray, the scientists can change how the genetically-engineered cells respond, and thus alter the speed and direction of the creepy raybot.
The living raybot lives in a specially-formulated nutrient bath at rat body temperature that has so far kept it alive for over six weeks. Due to the ray’s lack of immune system or other defenses from microbes, further experimentation and refining is needed before the ray can be let loose in a natural environment.
And thus, we begin altering the course of life on Earth forever. If science fiction has taught us anything, it’s that the ramifications of creating synthetic living things cannot be predicted or controlled. I, for one, welcome our new rat-heart-based overlords.