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This story is part of a series on current advances in regenerative medicine. This article discusses advances in regenerative devices and technologies.
In 1999, I defined regenerative medicine as a collection of interventions that restore normal function to tissues and organs damaged by disease, injured by trauma, or worn out over time. I include a full spectrum of chemical, gene and protein-based drugs, cell-based therapies, and biomechanical interventions that achieve that goal.
A future where microscopic machines permeate the human body to monitor vital signs and diseases may be closer than you think. What was once a figment of science fiction is now a reality as new swallowable vital-monitoring pills are completing their first human trials.
In a study for cell deviceDr. Giovanni Traverso of the Massachusetts Institute of Technology and his colleagues have described a new biosensor they call the VM Pill. The swallowable capsule contains sensors, a microprocessor to gather information, and a radio to send the information back to the physician. But how can such a pill be used to help people? Here, I will analyze his invention and discuss its use in a regenerative medicine context.
As Traverso and colleagues note, swallowable electronics are far from new technology. The first tests of such devices occurred in the 1950s, tracking simple measurements such as temperature and pH balance. However, the VM tablet is much more advanced.
The device is 25 mm long, or about the size of an adult's multivitamin. Inside a sealed plastic shell is a radio equipped with two batteries, a processing unit, an accelerometer, and an antenna. There is an antenna at the receiving end of the signal which feeds data into the monitoring software.
Figure 1: (B) VM pill, a vitamin-sized (9 × 25 mm) swallowable physiological monitoring device. , [+]
The researchers discuss two possible use cases for the device. The more speculative finding of the two is opioid overdose. For people who are struggling with opioid addiction or who are receiving heavy sedative medications, the VM pill may be used on a frequent basis to monitor for respiratory depression that may result from an opioid overdose. Upon detection, the VM pill can notify first responders, similar to a life-alert-style button device designed for the elderly.
They confirmed the detection capability of the VM pill by a controlled swine test in which one subject was given 250 micrograms of fentanyl, at which point the VM pill immediately detected overdose due to respiratory depression. The subject was then given a 1 mg dose of naloxone and rebounded, at which point the VM pill also detected recovery of breathing.
The second use is one they discover more importantly with their own testing: studying sleep. Traditional standard of care sleep observation requires sleeping in a medical lab, attached to a series of wires, resulting in discomfort and inconsistent results.
Sleep studies with the VM pill may allow observations at home while maintaining more consistent sleep settings during data collection.
Figure 2: (B) Standard of care for polysomnography. (C) Capsule-based sleep study evaluation.
Comparing the accuracy of the VM pill to a wired polysomnograph, Traverso and colleagues found that the pill was as accurate as the standard of care monitoring system. The accuracy of respiratory rate in the laboratory system was within one breath per minute, and heart rate was within two to three beats per minute, both within reasonable margins of error. Additionally, the VM pill could also detect when patients were holding their breathing or experiencing moments of sleep apnea. They also found that the VM pill maintained accuracy even when patients with sleep apnea used their ventilators.
So then, what are the limitations of the VM tablet? Two things that immediately come to mind are cost and duration of use. To address the latter, the VM pill can be used only during transit in the body, or for about 36 hours on average. This limits long-term monitoring use cases.
Additionally, based on the device's price per pill, patients will have to regurgitate it after it makes its way through the digestive tract, which is likely to limit enthusiasm for the device. If the pill is relatively inexpensive, given its size and simple design, it could be given to patients in bulk, similar to normal pills, but the study did not provide any cost estimates.
In addition to respiratory and heart rate monitoring, future applications for the pill could come from changes in its design, opening up other avenues of health monitoring. These may include digestive health, blood sugar monitoring, cancer cell detection, etc. I look forward to seeing how the system is adapted and implemented in the coming years.
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