I learned a new word this week: bioresorbable. It means pretty much what you might infer -- materials that can be broken down and absorbed into the body, i.e., biodegradable. It is not, as it turns out, a new concept for health care – physicians have been using bioresorbable stitches and even stents for several years. But there are some new developments that further illustrate the potential of bioresorbable materials.
Bioresorbable pacemaker.
Credit: Northwestern University/George Washington
It’s enough to make Green New Deal supporters smile.
Bioresorbable stents and stitches are all well and
good – who wants to be stuck with them or, worse yet, to need them removed? –
but they are essentially passive tools. Not
so with pacemakers, which have to monitor and respond. Medicine has made great progress in making
pacemakers ever smaller and longer lasting, but now we have a bioresorabable
pacemaker.
Researchers from Northwestern University and The George
Washington University just published their success with “fully
implantable and bioresorbable cardiac pacemakers without leads or batteries.” What their title might lack in pithy is more
than offset by the scope of what they’ve done.
Fully implantable! No leads! No batteries!
And bioresorbable!
Most pacemakers are, of course, designed to be
permanent, but there are situations where they are implanted on a temporary basis,
such as after a heart attack or drug overdose.
Dr. Rishi Arora, co-leader
of the study, noted:
“The current standard of care involves inserting a wire, which stays in place
for three to seven days. These have potential to become infected or dislodged.”
Dr. Arora went on to explain:
Instead of using wires that can get infected and dislodged, we can implant this leadless biocompatible pacemaker. The circuitry is implanted directly on the surface of the heart, and we can activate it remotely. Over a period of weeks, this new type of pacemaker ‘dissolves’ or degrades on its own, thereby avoiding the need for physical removal of the pacemaker electrodes. This is potentially a major victory for post-operative patients.
The device is only 15
millimeters long, 250 microns thick and weighs less than a gram, yet still
manages to deliver electric pulses to the heart as needed. It is powered and controlled using near field
communications (NFC); “You know
when you try to charge a phone wirelessly? It’s exactly the same principle,” GW’s
Igor Efimov, a co-leader of the study, told
StatNews.
It dissolves over a period
of days or weeks, based on the specific composition and thickness of the
materials.
Watch it dissolve:
The researchers are pretty pumped. Dr. Efimov says:The transient electronics platform opens an entirely new chapter in medicine and biomedical research. The bioresorbable materials at the foundation of this technology make it possible to create whole host of diagnostic and therapeutic transient devices for monitoring progression of diseases and therapies, delivering electrical, pharmacological, cell therapies, gene reprogramming and more.
They’re not the only ones. Moussa
Mansour, director of the Atrial Fibrillation Program at Massachusetts General
Hospital, who was not involved in the study, told
StatNews: “It seems to be a very revolutionary idea. I believe it’s
going to be well-received in the field. It targets an unmet need, and I believe
it’s going to benefit patients… not only because it targets a temporary patient
application, but because of its potential to be expanded to
other applications in medicine.”
Northwestern’s John A.
Rogers, who led the device development, predicts:
“Transient technologies, in general, could
someday provide therapy or treatment for a wide variety of medical conditions —
serving, in a sense, as an engineering form of medicine.”
Let that sink in: “An engineering form of medicine.”
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Then there is a fracture electrostimulation device
(FED). Researchers at the University of
Wisconsin have
developed an implantable, self-powered, bioresorbable device that stimulates
bone growth and healing, then dissolves when its job is done. The device gets its power by converting
mechanical energy generated by tiny movements into electric power, which then
stimulates the bone. In some situations,
they admit, “We may need the device to respond to other types of internal
mechanical sources, like blood pressure changes.”
The FED. Credit: Jason Daley/UW
As with the pacemaker, the device can be “fine tuned”
to last from weeks to months by “tweaking” the make-up of the materials.
Right now, the device has only been tested on rats,
but lead researcher Xudong Wang is eager for the next steps: “It will be very
interesting and impactful to address the development from animal to human.”
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If you think those are cool, then hold still for bioresorbable 3D printed tissue scaffolds. Tissue scaffolds, if you didn’t know (I didn’t) are used in tissue engineering to provide structures for tissue growth/repair/regeneration, such as after breast cancer treatment. The study concludes:
We have demonstrated that it’s possible to produce highly porous scaffolds with shape memory, and our processes and materials will enable production of self-fitting scaffolds that take on soft tissue void geometry in a minimally invasive surgery without deforming or applying pressure to the surrounding tissues. Over time, the scaffold erodes with minimal swelling, allowing slow continuous tissue infiltration without mechanical degradation.
These new scaffolds offer several advantages over
current approaches, including better elasticity, more ability to retain “shape
memory” after compression, compatibility with tissues, and, of course, being
bioresorbable. The researchers describe
them as “4D” materials because how the materials change over time is a factor.
Bioresorbable tissue scaffolds
Credit: University of Birmingham
The researchers believe: “By focusing on the design of
a material with a unique combination of features, we have been able to achieve
a minimally invasive 4D structure that could reduce surgical impact while
enhancing rates of healing and patient recovery.”
Again, they’re not yet testing on humans, but a
separate study – the INSPIRE
study – has tested a Neuro-Spinal Scaffold that is made of a bioresorbable
polymer on patients with a severe spinal cord injury, demonstrating
“that the potential benefits of
the NSS outweigh the risks in this patient population and support further
clinical investigation in a randomised controlled trial.”
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I love the idea of using bioresorbable materials in
health care. I love the idea of an engineering
form of medicine, just as I love the idea of a biochemical form of
medicine. Much of the history of
medicine has involved inserting foreign substances/materials into us, with
varying degrees of violence and success.
Bioresorbable approaches should
give us better options.
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