Andrew P Street
Andrew P Street is a widely published journalist, non-fiction author and former columnist for the Sydney Morning Herald.
Every so often the march of research seems to take an abrupt turn into the realm of science fiction. For example, a new paper in the journal Science Robotics contains the tantalising promise of cell-regenerating robots acting within a living body.
Before you thrill to images of Star Wars bacta tanks or swarms of tiny nanobots zipping along the bloodstream, be advised that the reality is rather less visually dazzling – but far more scientifically exciting.
An international, multi-institutional team led by Dana Damian of Boston Children’s Hospital in the US has created a robotic implant that is, the researchers write, “designed to induce lengthening of tubular organs, such as the oesophagus and intestines, by computer-controlled application of traction forces”.
There are significant structural challenges involved in repairing tubular structures in the body, which is a problem since most biological creatures – including we humans – are chock-full of them.
Current solutions such as organ transplantation are high cost and high risk, while the surgical treatment options for conditions such as long-gap oesophageal atresia (a closure or severing of the oesophagus) require a patient to be sedated in traction for a number of weeks as the sections of are gently stretched and reconnected.
By comparison, the pigs used to test the robotic device designed by Damian’s team remained not just alive, but awake and mobile while an implant was attached to their oesophagus.
The implant mechanically increases cell growth by using mechanical stimulation to speed up normal healing.
That process, properly called mechanostimulation, is not a new technology: it was first described in the 1930s and is a common technique for growing cell cultures, among other uses.
However, improvements in microelectronics has meant that the necessary mechanics required for the process can now be made in an implantable size.
The advantage of this technique over current practice is not merely time, but the development of living tissue avoids some significant problems. Current treatment, in which the tissue expansions are carried out in separate steps over hours or days increases the risk of conditions such as fibrosis and poorer nerve reconnection.
In the process outlined in the paper, a robotic implant about ten centimetres long is attached to the outside of the organ with two steel ‘O’ rings fixed around the tubular sections of the oesophagus. The unit containing the motor, sensors and electronics is sheathed in a biocompatible waterproof skin and connected by cable to a wearable control unit outside the body, and mechanostimulation encourages cell growth in the area between the rings.
The results were encouraging. Over nine days the implant extended the test pigs’ oesophageal length by 77% between the two rings, not by stretching the organ but by stimulating cellular growth within it. During this period the organ also experienced normal blood flow and functionality.
The researchers even speculate that future tweaks to the system to recognise the muscular contractions and relaxation marking digestion may even permit the subject to eat while undertaking the procedure.
So, not quite the sci-fi dream of swarms of cell-droids bots zapping our insides to health, but maybe tube-stretching robots are not as far away from them as you’d imagine.
As the authors point out, “Beyond their use for organ growth, robotic implants represent a new direction in medical robotics. These bionic systems can assist in performing normal body functions either temporarily, until the body repairs itself, or permanently.
“The ongoing miniaturisation of sensors and actuators, together with the continuing development of techniques for wireless communication, power transfer, and energy scavenging, may lead to devices surpassing even those proposed in science fiction.”
