Anyone who has walked through fertility treatment knows the quiet burden of needles and calendars, the weeks of injections timed to a body's rhythm. In a laboratory at Yonsei University, researchers have tried to fold that long choreography into a single small patch that releases its hormones one after another, on its own schedule. Tested so far only in rabbits, the approach matched the ovulation results of repeated injections while easing the bodily strain that sometimes follows an overly strong response. It is an early step, one that points toward a gentler future for patients, though much r
Microneedle Patch Replaces Four Fertility Injections With One, Cutting Fluid Buildup in Rabbit Study
One patch, left in place for three days, did the work of four injections
Mark
So what actually changed here? Four injections became one patch?
Mimi
Yes. In rabbits, one patch with FSH in the outer hydrogel layer and hCG in the inner layer replaced three FSH shots and one hCG shot. Heating it to about 50°C for 30 seconds after three days triggers the second hormone.
Mark
And it worked as well?
Mimi
On ovulation, the groups were statistically comparable: mature oocytes, ovulated oocytes, ovulation rate and recovery rate. Ovarian tissue looked similar too.
Luke
Comparable isn't the same as proven equal, though. Differences fell below the significance threshold, and the source gives no group sizes. That's worth keeping in mind.
Mark
What about the safety side, the OHSS piece?
Mimi
Patch rabbits had less abdominal fluid, less dye leakage, lower VEGF and IL-6, and clotting measures close to untreated animals. The injection group showed increased clot firmness.
Luke
Those are markers in rabbits, not OHSS in patients. And there's a confound: the patch carried about 33% more of each hormone than the injections. So the reduction came despite higher loading, but the researchers themselves say a dose-matched study is still needed.
Mark
Why would a gentler curve matter?
Mimi
Injections produced repeated sharp spikes in FSH, while the patch rose and fell more gradually with a lower hCG peak. That smoother profile is the plausible link to less leakage, though the team hasn't isolated it yet.
Luke
Plausible, not shown. And nobody knows yet whether it works in human skin, whether release is reproducible over time, or whether it affects pregnancy. No pregnancy outcomes were measured.
Mark
So what's next?
Mimi
Human skin insertion and shape recovery tests, stability studies, infertility models for pregnancy outcomes, and the dose-matched comparison.
Der Puls
- A patient's weeks of repeated hormone injections are being challenged by a single patch that must do the work of four.
- The rabbit study shows matching ovulation outcomes, yet the patch carried about 33% more hormone than the injections, a caveat the team openly flags.
- Patch-treated animals showed less abdominal fluid, less vascular leakage and lower clotting-related markers linked to ovarian hyperstimulation syndrome.
- Heat triggers a shape change in each needle to release the second hormone, and the researchers are now planning matched-dose follow-up work.
- Human skin trials, long-term release stability and pregnancy outcome studies still stand between this prototype and any clinical use.
Anyone who has walked through fertility treatment knows the quiet burden of needles and calendars, the weeks of injections timed to a body's rhythm. In a laboratory at Yonsei University, researchers have tried to fold that long choreography into a single small patch that releases its hormones one after another, on its own schedule. Tested so far only in rabbits, the approach matched the ovulation results of repeated injections while easing the bodily strain that sometimes follows an overly strong response. It is an early step, one that points toward a gentler future for patients, though much remains to be proven before it reaches human hands.
A single patch, pressed into a rabbit's skin and left in place for three days, accomplished what usually takes four separate hormone injections. The study, led by a team from Yonsei University and published in Advanced Functional Materials, speaks to a problem many people in fertility treatment know well: the pain of repeated shots and the discipline of keeping to a strict schedule.
Controlled ovarian stimulation depends on two hormones given in order. First comes follicle-stimulating hormone, which helps follicles grow, and then human chorionic gonadotropin, which triggers the final maturation of the egg. When the ovaries respond too strongly, a condition called ovarian hyperstimulation syndrome can develop, with fluid leaking into the abdomen and blood thickening enough to raise clotting risk.
The researchers built a microneedle with two layers of gelatin-based hydrogel. The outer layer holds the first hormone and dissolves slowly over 72 hours. The inner layer holds the second. After three days, gentle heat reshapes each needle, breaking the inner layer and releasing the second hormone over the following day.
The results were encouraging. Ovulation outcomes matched those of the injection group, and the blood profiles were gentler, with fewer sharp spikes. Patch-treated rabbits also showed less abdominal fluid, less vascular leakage and lower inflammatory and clotting markers.
The team is candid about one limitation: the patch carried roughly a third more hormone than the injections. They plan to repeat the work with matched doses. Human skin trials, long-term stability tests and pregnancy outcome studies still lie ahead. Still, the lead researcher sees the platform as a possible model for other treatments that require several drugs delivered in sequence.
A single patch, pressed into the skin of a rabbit and left for three days, did the work that normally takes four separate hormone injections. That is the central result of a study from Yonsei University announced on October 26, 2026, and published in Advanced Functional Materials.
The problem it addresses is familiar to anyone who has been through fertility treatment. Controlled ovarian stimulation relies on two hormones in a set order. Follicle-stimulating hormone, or FSH, encourages follicles to grow. Then human chorionic gonadotropin, or hCG, triggers the final maturation of the egg and ovulation. Patients face the pain of repeated injections and the work of keeping to a schedule. An overly strong ovarian response can also cause ovarian hyperstimulation syndrome, or OHSS, in which fluid leaks out of blood vessels into the abdomen and the thickened blood raises clotting risk.
The research team included Professors Hak-Joon Sung, Sungwoo Cho and Seung Eun Yu and student Hyunjae Kim of the Department of Medical Engineering, together with Professor Young Sik Choi of the Department of Obstetrics and Gynecology at Severance Hospital. They built a shape-memory microneedle whose needles are 700 micrometers long and coated with two layers of gelatin-based hydrogel. FSH sits in the outer layer and hCG in the inner one.
Once the patch is in the skin, the outer layer degrades slowly and releases FSH over 72 hours. Heat then changes the cross-section of each needle from an X shape to an O shape. That breaks the inner hydrogel and pushes out hCG, which is released over the next 24 hours.
In rabbits, the team compared the patch with the conventional approach. The injection group received 75 IU of FSH at 24-hour intervals for three doses, then one 750-IU injection of hCG. The microneedle group received one patch loaded with 300 IU of FSH and 1,000 IU of hCG. After three days, the patch was warmed to about 50°C for 30 seconds to start the hCG release.
Ovulation results were comparable. The proportion of mature oocytes, the number of ovulated oocytes, the ovulation rate and the oocyte recovery rate showed differences that did not reach statistical significance. Counts of preovulatory follicles and corpora lutea in ovarian tissue were similar as well.
The blood profiles differed. Repeated injections produced a series of sharp rises in circulating FSH, while the patch group showed a gentler rise and fall and a lower peak hCG concentration. On the OHSS markers, patch-treated rabbits had less abdominal fluid and less tracer dye leaking into the abdominal cavity. Their blood levels of VEGF, which promotes vascular permeability, and the inflammatory molecule interleukin-6 were lower. Ovarian tissue showed higher expression of proteins that hold together the cells lining blood vessels. Clot firmness rose after treatment in the injection group, but in the patch group it stayed comparable to rabbits given no hormones. Ovarian swelling and inflammatory markers were also lower than with injections.
There is an important caveat in the design. The patch carried roughly 33% more of each hormone than the total given by injection. The researchers say they set the loading amounts by considering overall exposure in the blood over time, and they plan a follow-up study with matched doses to see how the release pattern itself affects ovulation and OHSS outcomes.
The path to clinical use remains long. The team lists long-term stability and reproducibility of hormone release, and tests of needle insertion and shape recovery in human skin. They also need infertility animal models to assess pregnancy outcomes, and adjustments to device and dose for individual stimulation schedules. Sung said the work offers a way to change drug delivery at the required moment through a change in needle shape, and that the team hopes to develop it into a platform for treatments needing several drugs in sequence.
Bemerkenswerte Zitate
The study presents a new approach to changing drug-delivery patterns at the required time through changes in microneedle shape, and the team plans to develop it into a platform for treatments requiring sequential delivery of multiple drugs.— Professor Hak-Joon Sung, Yonsei University
Möchten Sie die ganze Geschichte?
Das Original lesen bei 헬스코리아뉴스 ↗
Health & Medicine