This Phase 1 split-site pilot study will evaluate the safety and dermal tolerability of a topical exosome-containing liquid in 10 healthy adult volunteers. The investigational liquid will be applied to a small defined area of intact skin. A vehicle liquid without exosomes may be applied to a matched contralateral skin site as a control. The study will assess local skin reactions, systemic adverse events, vital signs, clinical laboratory parameters, and feasibility of topical administration. No burn wound or artificial skin wound will be induced in participants in this Phase 1 safety study.

The investigational product is a sterile topical exosome-containing liquid being developed for future evaluation in burn wound repair. Preclinical in vivo evaluation in murine wound models suggested improved wound closure and better histological organization of repaired skin after topical exosome-containing formulation administration, with the therapeutic effect being more pronounced in the thermal burn model. In the burn model, the exosome-containing formulation group showed faster wound-area reduction, improved epidermal and dermal organization, reduced inflammatory cellularity, and no significant body-weight differences compared with control groups.

This first-in-human Phase 1 study is designed to evaluate safety and dermal tolerability in healthy adult volunteers before the product is tested in patients with burn wounds. No artificial burn wound or skin wound will be created. The investigational liquid will be applied to a small defined area of intact skin according to the protocol-defined dose and schedule. If a split-site design is used, vehicle liquid without exosomes will be applied to a matched contralateral intact skin site as a control. Participants will be monitored for local skin irritation, erythema, edema, pruritus, burning sensation, pain, rash, allergic reaction, systemic adverse events, vital signs, and clinical laboratory abnormalities.

The first two participants will be enrolled as sentinel participants. Safety data through at least 72 hours after first application will be reviewed before enrollment of the remaining participants. The main purpose of the study is to determine whether topical administration of the exosome-containing liquid is safe and tolerable on intact human skin.

Inclusion Criteria:

1. Healthy adult volunteers aged 18 to 55 years.
2. Able and willing to provide written informed consent.
3. No clinically significant abnormality based on medical history, physical examination, vital signs, and screening laboratory tests.
4. Intact healthy skin at the planned application sites.
5. Willingness to avoid applying other topical products, cosmetics, antiseptics, or irritant substances to the application sites during the study period.
6. Willingness to avoid excessive sun exposure, sauna, swimming pool use, and mechanical irritation of the application sites during the study period.
7. Willingness to comply with all study visits, topical application procedures, local skin assessments, skin photography, safety assessments, and follow-up.
8. For women of childbearing potential, a negative pregnancy test before first application and willingness to use an acceptable method of contraception during the study period.

Exclusion Criteria:

1. Any active skin disease, dermatitis, eczema, psoriasis, urticaria, acneiform eruption, skin infection, open wound, scar, tattoo, burn scar, pigmentation disorder, or clinically significant skin abnormality at the planned application sites.
2. History of severe allergy, anaphylaxis, or hypersensitivity to topical liquids, dressings, biological products, exosome-containing products, or any component of the investigational product or vehicle liquid.
3. Current acute illness, fever, or active infection.
4. Known autoimmune disease, immunodeficiency, or current systemic immunosuppressive therapy.
5. Use of systemic corticosteroids, immunomodulatory drugs, biological agents, or investigational products within 30 days before enrollment.
6. Use of topical corticosteroids, topical immunomodulators, topical antibiotics, retinoids, keratolytic agents, or other medicated topical products on or near the planned application sites within 14 days before enrollment.
7. Clinically significant hepatic, renal, cardiovascular, hematologic, endocrine, neurologic, psychiatric, or systemic disease that may increase risk or interfere with interpretation of study results.
8. Known active malignancy or history of malignancy within the past 5 years.
9. Positive screening test for clinically relevant transmissible infection, if required by the protocol.
10. Pregnancy or breastfeeding.
11. Positive pregnancy test at screening or before first application in women of childbearing potential.
12. Participation in another interventional clinical trial within 30 days before enrollment.
13. Blood donation or major blood loss within 30 days before enrollment, if laboratory safety monitoring is included in the protocol.
14. Any condition that, in the investigator's judgment, would make participation unsafe or interfere with interpretation of study results.

No. Individual participant data will not be shared because this is a small Phase 1 first-in-human safety and dermal tolerability study in 10 healthy volunteers, and de-identified individual-level data may still carry a risk of participant re-identification. Aggregate study results, adverse event summaries, and protocol-defined outcome summaries may be reported in ClinicalTrials.gov and in peer-reviewed publications.