Studying Seaweed-Derived Hydrogel for Retinal Issues

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Could seaweed hold a key to future retinal treatments? Researchers from Pohang University of Science and Technology in Pohang, South Korea, and colleagues who are looking for a novel way to treat retinal detachment have published early research exploring the potential of alginate for ophthalmic use. A naturally occurring gelatinous substance, alginate is derived from seaweed.

Their thought is that an artificial vitreous body made from alginate might be a better alternative than using standard agents for vitreous tamponade after vitrectomy to stabilize the retina for conditions such as rhegmatogenous retinal detachment, severe diabetic retinopathy, penetrating ocular trauma, macular hole, and proliferative vitreo­retinopathy.

SOURCING SEAWEED. Researchers are exploring the potential of alginate for retinal detachment treatments. A naturally occurring gelatinous substance, alginate is derived from seaweed.

Current practice. The silicone oil and expansile gases used in vitrectomy are meant to stabilize the retina but can cause side effects, including retinal toxicity, cataract formation, secondary glaucoma, and uveitis. Silicone oil, for example, can lead to corneal decom­pensation and glaucoma and is not bio degradable. And a second surgery to remove the material is required over time.

A drawback to using expansile gases is that patients have to remain in a prone position for a few days following gas tamponade, said lead study author Hyung Joon Cha, PhD, SeAH Chair Professor and Dean of Engineering at the Department of Chemical Engineer­ing and the School of Convergence Science and Technology at Pohang.¹

“This is required for as long as the eye is filled with gas, essentially. During this period, the patient will experience significantly impaired vision,” he said.

Why seaweed. Dr. Cha and col­leagues, an interdisciplinary team of chemical engineers and ophthalmolo­gists, published their findings—tested only in rabbit eyes, so far—in the jour­nal Biomaterials. They chose to study alginate, a polysaccharide extracted from marine brown seaweed, because it “has been one of the most widely used natural biomaterials for tissue engi­neering. Alginate is not biodegraded in mammals and can be retained for a long time in the body,” the authors wrote.

From seaweed to animal eyes. Through a series of chemical pro­cesses, they cre­ated an alginate medical compos­ite hydrogel—more specifically, according to the study, a transpar­ent alginate-phen­ylboronic acid/ polyvinyl alcohol composite hydro­gel novel vitreous substitute with tamponading capabilities. They injected it into the eyes of a rabbit mod­el of vitrectomy retinal detachment to test their theory. The authors reported that “in vivo evaluations confirmed [the hydrogel’s] ability to inhibit retinal detachment recurrence and preserve rabbit vision without adverse effects.”

“Alginate is a very stable polysac­charide molecule because mammals, including humans, lack enzymes for alginate degradation,” said Dr. Cha.

Dr. Cha said the alginate hydrogel also quickly formed in situ after intraocular injection, noting that “while silicone oil has its own refractive index that requires optical adjustments and can also cause corneal decompensation and glaucoma, the refractive index of our alginate hydrogel is similar to the refractive index of native human vitreous and has a tamponading effect similar to that of silicone oil.”

Early days. J. Fernando Arevalo, MD, PhD, Chairman of Ophthalmolo­gy at Johns Hopkins Bayview Medical Center and Professor of Ophthalmolo­gy, said that the new hydrogel material seems to present some positive benefits over traditional tamponading agents. But Dr. Arevalo, who was not involved in the research, said it’s important to emphasize that, as of now, this is very experimental.

Dr. Arevalo said the fact that the hydrogel is described as “transparent” is crucial, given that it would not obstruct vision. He also said that the idea that this material might one day help repair the retina or “integrate seamlessly with­in the eye” is an intriguing theory that needs further study. The notion that the mechanical properties of the hydrogel might one day be adjustable is also an interesting concept, said Dr. Arevalo. And given that alginate is known for being biocompatible means there might be a reduced risk of immune reactions or other complications, he said. But again all of these factors would require further study.

“It is promising. However, it’s im­portant to note that while new materi­als may offer theoretical benefits, they must undergo rigorous clinical testing to ensure they are safe and effective in actual practice,” Dr. Arevalo said, noting that only human studies will be able to confirm its potential.

He said the big question is, will it cause cataracts in humans? “If not, that would be a great advancement over gas and silicone oil.”

Looking to the future. Dr. Cha said the next step will be to standardize the formulation and authorize biological safety assessments and preclinical eval­uations using larger animal models.

—Brian Mastroianni

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1 Choi G et al. Biomaterials. 2024;305:122459.

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Relevant financial disclosures—Dr. Arevalo: None. Dr. Cha: None.

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