Credit score: Columbia College
What does it take to design a brand new needle for medical use? When the needle must be a lot thinner and sharper than any commercially present needle and designed to ship remedies to a beforehand inaccessible tissue, the reply is years of collaboration between a close-knit workforce of physicians and engineers.
The needle’s Columbia creators—ENT surgeon Anil Lalwani and mechanical engineer Jeffrey Kysar—are satisfied their ultrasharp and ultrathin gadget will quickly develop into a necessary instrument in the best way listening to loss and different circumstances of the inside ear are handled. “It’s not an exaggeration to say our microneedle could be key to precision medicine for the inner ear,” Lalwani says.
In an interview, the 2 mentioned how they started their partnership a dozen years in the past, what goes into designing a medical gadget, and why they suppose their microneedle will revolutionize remedies for listening to loss and different circumstances of the inside ear.
Why does drugs want this needle?
AL: We’re now on the cusp of gene therapies that may restore listening to by regenerating cells in our ears that we lose after years of publicity to loud noises. However we actually do not have a option to ship these therapies in a exact, predictable, and protected means.
That is as a result of these cells are inside an nearly inaccessible container within the inside ear referred to as the cochlea. The cochlea is a spiral-shaped, fluid-filled bone, the toughest bone in our our bodies
There’s a tiny membrane—about 2 mm broad—within the cochlea that would theoretically give us entry. However the membrane invariably rips while you attempt to make a gap with normal surgical instruments. When that occurs, you may completely lose your listening to and sense of steadiness.
In order that’s one purpose we have been engaged on this microneedle: to introduce therapies into the cochlea with out ripping the membrane.
Cells within the cochlea after injection through the microneedle of a gene remedy vector (backside row) and a management answer (prime row). Credit score: Anil Lalwani and Jeffrey Kysar/Columbia College
The opposite is to make use of the needle to take away liquid from the cochlea for the analysis of inside ear problems, like Meniere’s illness, which causes dizzy spells, nausea, and listening to loss. By sampling the liquid within the inside ear, we could possibly perceive Meniere’s higher, which can even assist us discover higher remedies sooner or later.
How did the 2 of you begin collaborating?
AL: We truly had our meet-cute or cute-meet, no matter that is referred to as, by two of our postdocs, who had been pals. They realized we might kind a extremely good partnership.
JK: I had imagined that medical doctors might entry anywhere within the human physique. However once I first met Anil, he informed me that, no, the inside ear was just about an unknown entity: nothing could possibly be injected or faraway from it. That is what captured my consideration.
That Saturday, I feel, I went to the bookstore and picked up a guide on human anatomy. I then began trying within the biomedical engineering literature to see what was identified in regards to the membrane. And I discovered little or no. What number of unexplored tissues are left within the human physique to review? This one had some very fascinating properties, each geometric and mechanical, so it appeared like a incredible alternative for me.
What had been a number of the challenges in creating the needle?
JK: So let me speak somewhat bit in regards to the principle of why issues break. That is the final theme of my analysis.
From an engineering perspective, you’ll be able to consider the membrane as a tarp that is been pulled tightly. If you happen to put a extremely small gap within the tarp, that gap is not going to develop spontaneously. But when the outlet is larger than a crucial measurement, it should develop spontaneously and rip the tarp. Engineering principle tells us that if we are able to introduce a gap within the membrane that is smaller than this crucial measurement, the membrane will not rip.
The twin-lumen microneedle as seen by an electron microscope. Credit score: Jeffrey Kysar/Columbia College.
We simply needed to make a microneedle smaller than that crucial measurement, in regards to the width of a human hair within the case of the membrane. It is usually vital for the needle to be ultrasharp with the intention to reduce injury to the tissue through the perforation course of, which promotes therapeutic of the membrane after the process.
We tried lots of other ways to fabricate the needle. Not lengthy after we began our collaboration, a 3D printing technique grew to become out there and that was the enabling expertise. Two photon photolithography permits a so-called voxel decision of round 200 nanometers, a few tenth of a p.c of the diameter of a hair, very, very small. With that, we are able to print needles which can be extraordinarily sharp and are constituted of polymers, just like the epoxy you should buy in a ironmongery store. Our needles are many instances sharper than any commercially out there needle.
We put lots of effort and time into ensuring that the needles are sufficiently sturdy. We had examples that broke, or the channels inside did not kind correctly, or the tip blunted. That is half and parcel of what we do as engineers, work out how we are able to enhance the design.
How have you learnt these needles will do what you need them to do?
AL: We have executed dozens and dozens of animal surgical procedures, and we have by no means seen any unfavourable results or listening to loss. The microneedle would not make a gap larger than the dimensions of the needle, and the outlet heals inside 48 hours or so.
We have additionally proven the potential worth of the microneedle, since this area did not exist till we created the gadget.
In certainly one of our most up-to-date papers [published in Academic Radiology], we used the microneedle to inject a distinction agent into the inside 12 months of guinea pigs so we might use MRI to take a look at the sizes of various chambers within the cochlea. That will help us with diagnosing Meniere’s illness, wherein the center chamber turns into a lot larger. Proper now, imaging the human cochlea is tough. If we are able to diagnose Meniere’s extra precisely, that ought to result in higher medical trials and finally higher remedies.
In a second latest examine [published in Otology & Neurotology], we present that we are able to ship siRNA—a kind of gene remedy—in a dependable, protected style, with out inflicting listening to loss. We needed to make it possible for there is no toxicity of the automobile [liposomes] itself, but in addition that the remedy is distributed all through the cochlea.
With the microneedle, a distinction agent might be injected into the inside ear and can assist physicians see adjustments within the cochlea that would assist them diagnose circumstances like Meniere’s illness. Right here, MRI photos of a guinea pig cochlea reveal the cochlea’s totally different compartments. Credit score: Anil Lalwani/Columbia College Vagelos Faculty of Physicians and Surgeons
What’s subsequent?
JK: With gene remedy, we’re anticipating that comparatively massive volumes of the therapeutic will should be injected into the cochlea, and since the cochlea is a closed house, we’ll have to take away liquid as we inject. In any other case, the strain within the inside ear will enhance and doubtlessly injury the sense of listening to and steadiness. That is why we designed the twin lumen microneedle, which is able to permit us to inject the therapeutic by one lumen and aspirate fluid by the opposite lumen concurrently with out altering the inside ear strain.
AL: We fashioned an organization a few 12 months and a half in the past now, referred to as Haystack Medical, with the purpose of commercializing microneedles. We’re actually excited in regards to the subsequent steps in translating this expertise to make use of in folks. Proper now, we’re speaking to different corporations creating gene therapies about utilizing our expertise. With the microneedle, you may doubtlessly inject the remedy time and again in the identical particular person with out inflicting listening to loss. You could possibly see if the gene remedy is lively, or if you want to readminister the fabric. That is doable with the microneedle as a result of it would not scar or terminally injury the portal to the inside ear.
General, we expect the microneedle goes to open the door—for the primary time—to protected and dependable analysis and therapies for circumstances that have an effect on the inside ear.
JK: We’re each very grateful to our excellent workforce of scholars, postdocs, medical college students, and our engineering colleague Elizabeth Olson, professor of biomedical engineering, in addition to medical clinicians and surgeons who’ve been and are part of our workforce.
Extra data:
Chaoqun Zhou et al, Distinction Enhancement of Cochlea after Direct Microneedle Intracochlear Injection of Gadodiamide by the Spherical Window Membrane with Minimal Dosage, Educational Radiology (2024). DOI: 10.1016/j.acra.2024.10.022
Sharon J. Feng et al, Microneedle-Mediated Supply of siRNA through Liposomal-Primarily based Transfection for Inside Ear Gene Remedy, Otology & Neurotology (2024). DOI: 10.1097/MAO.0000000000004297
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