Injectable microgels for targeted keloid radiotherapy

Keloids are scar tissues that form when skin fibroblasts overreact to injury, resulting in excess collagen and potentially painful, itchy growths. Existing keloid treatments, such as surgery, corticosteroids, lasers and radiotherapy, often involve lengthy procedures with limited success in preventing recurrence. Conventional radiation therapies face difficulties in precisely targeting the small, irregular keloid lesions while avoiding damage to surrounding healthy tissue.

A team of researchers from Pusan National University, led by Seung Yun Yang (also CEO of SNVIA Co., Ltd.), has developed an injectable microgel system to deliver targeted radiation directly into keloid tissues. Yang explained that they "developed an off-the-shelf microbrachytherapy approach using injectable, biodegradable hyaluronic acid (HA) microgels for keloid treatment."

The researchers created uniform, biodegradable HA microgels using microfluidic technology and freeze-drying, which produced a porous structure capable of rapidly absorbing a radioactive iodine-131 solution. The microgels were labeled with ¹³¹I and tested on fibroblasts derived from patient keloids to assess their cytotoxic effects. The microgels were then injected into mice carrying patient-derived keloid tissue to evaluate their therapeutic efficacy, radioactive retention, biodistribution and safety.

The microgels demonstrated rapid and efficient radiolabeling, achieving 90% iodine-131 labeling within 10 minutes. After injection, the microgels remained localized within the keloid tissue for up to 14 days. In vitro studies showed that ≥10 MBq doses of ¹³¹I-HA microgels induced over 80% fibroblast death within 48 hours, primarily through apoptosis.

Administered intralesionally, the ¹³¹I-HA microgels reduced keloid size by approximately 70% within two weeks in a xenograft model, while sparring surrounding healthy tissues from off-target biodistribution or damage.

No significant abnormalities were observed in the treated mice's thyroid function, blood parameters, or major organs. The researchers believe this platform could simplify the preparation and delivery of localized brachytherapy, potentially reducing radioactive waste and logistical demands while allowing treatment to be tailored to individual lesions. The approach may also be adaptable for treating other localized tumors, though further studies are required to assess its applicability beyond keloids.

According to Yang, this technology offers a minimally invasive method to deliver precise local radiotherapy, addressing the targeting limitations of conventional external-beam radiation for small, irregular keloid lesions. The preclinical findings provide a promising foundation for targeted microbrachytherapy in keloid treatment, although longer-term studies are still needed to fully evaluate recurrence rates, immune responses, dose distribution, and clinical safety.