Injectable microgels for targeted keloid radiotherapy

Keloids are abnormal fibroproliferative scars that form when overactive fibroblasts produce excessive collagen after skin injury. Unlike ordinary scars, they can extend beyond the original wound and cause itching, pain and tenderness.

Current treatments, including surgery, corticosteroid injections, lasers and radiotherapy, may require prolonged treatment and can be associated with recurrence. Although radiotherapy can suppress keloid growth, conventional external-beam approaches struggle to precisely target small, irregular lesions while sparing surrounding healthy tissue.

To address this challenge, researchers from Pusan National University, led by Seung Yun Yang, who also serves as CEO of SNVIA Co., Ltd., developed an injectable system designed to deliver radiation directly within keloid tissue.

Yang explains, “We developed an ‘off-the-shelf’ microbrachytherapy approach using injectable, biodegradable hyaluronic acid (HA) microgels for keloid treatment.” The researchers investigated whether freeze-dried HA microgels could provide rapid and sustained local delivery of radioactive iodine-131 (¹³¹I) while minimizing systemic exposure.

This paper was published in Journal of Controlled Release.

The researchers fabricated uniform, biodegradable HA microgels using microfluidic technology and freeze-drying, creating a porous structure that could rapidly absorb radioactive solution. The microgels were then labeled with ¹³¹I and evaluated using patient-derived keloid fibroblasts to assess cytotoxicity and apoptosis. Their therapeutic efficacy, radioactive retention, biodistribution and safety were subsequently evaluated in mice carrying patient-derived keloid tissue.

The microgels enabled rapid and efficient radiolabeling. “Through absorption-mediated rapid radiolabeling, our freeze-dried microgels achieve high labeling efficiency (>90%) of iodine-131 in less than 10 minutes,” Yang said. Following injection, the microgels remained localized within keloid tissue for up to 14 days. In vitro, ¹³¹I-HA microgels at doses of ≥10 MBq induced more than 80% keloid fibroblast death within 48 hours, primarily through apoptosis.

Intralesional injection also reduced keloid size by about 70% after two weeks in a xenograft model, without off-target biodistribution or damage to surrounding healthy tissues. No significant abnormalities were observed in thyroid function, blood parameters or major organs.

The team believes the platform could simplify the preparation and delivery of localized brachytherapy. On-site radiolabeling may reduce radioactive waste and logistical demands while allowing treatment to be tailored to individual lesions. The approach could potentially be adapted for other localized tumors, although further studies are needed to assess its broader applications.

Yang concludes, “This technology provides a minimally invasive approach to deliver precise local radiotherapy, overcoming the targeting limitations of conventional external-beam radiation for small, irregular lesions.” Overall, the findings provide a promising preclinical foundation for targeted microbrachytherapy for keloids. Longer-term studies are still needed to evaluate recurrence, immune responses, dose distribution and clinical safety.

Who’s behind this story?

Swati Mestri

Swati Mestri holds a bachelor’s degree in Electronics Engineering and has worked as a content editor since 2019. She has experience editing research documents across technology, health care, and materials science, and has a particular interest in technology and space.

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Robert Egan

Bachelor’s in mathematical biology, Master’s in creative writing. Well-traveled with unique perspectives on science and language.

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