The goal of this clinical trial is to learn if local scalp injection of human umbilical cord mesenchymal stem cell-derived exosomes (hUCMSC-Exos) can treat androgenetic alopecia (AGA) in male patients with AGA.

The main question it aims to answer is:

Does hUCMSC-Exos injection improve hair regrowth compared with placebo?

Researchers will compare hUCMSC-Exos injection to placebo injection to see if hUCMSC-Exos leads to superior efficacy in hair follicle regeneration, as measured by changes in hair density, hair thickness, and patient-reported outcomes.

Participants will:

Receive randomized, double-blinded local scalp injections of either hUCMSC-Exos or placebo

Attend scheduled follow-up visits for hair assessment and safety monitoring

Undergo photography, trichoscopy, and complete quality-of-life or psychosocial burden questionnaires as applicable

Androgenetic alopecia (AGA) is a chronic, progressive condition characterized by gradual miniaturization of hair follicles in a patterned distribution, primarily influenced by genetic susceptibility and androgen-mediated signaling pathways. The condition involves disruption of the hair cycle, particularly shortening of the anagen phase and progressive conversion of terminal hair follicles into vellus-like follicles, ultimately resulting in visible hair thinning and reduced hair density. In addition to its dermatological manifestations, AGA is associated with significant psychological burden, including decreased self-confidence and impaired quality of life.

Current pharmacological interventions mainly aim to slow disease progression rather than fully restore follicular function. However, their limited efficacy and dependency on continuous administration highlight the unmet need for regenerative and disease-modifying therapeutic strategies.

Mesenchymal stem cell-derived exosomes (MSC-Exos) represent a novel class of cell-free biologics with regenerative and immunomodulatory properties. These nano-sized extracellular vesicles contain bioactive molecules such as proteins, lipids, and nucleic acids, which mediate intercellular communication and regulate multiple biological processes. Among different MSC sources, human umbilical cord-derived MSCs are considered to possess advantageous biological characteristics, including higher proliferative capacity, lower immunogenicity, and more stable paracrine activity, making their exosomes particularly suitable for clinical translation.

Experimental studies have demonstrated that MSC-Exos may influence hair follicle biology through multiple complementary mechanisms, including modulation of dermal papilla cell activity, regulation of signaling pathways involved in follicular cycling, enhancement of vascular support within the perifollicular environment, and attenuation of local inflammatory responses. These combined effects may contribute to the reactivation of dormant follicles and support the transition of hair follicles into the anagen growth phase.

This clinical investigation is designed to translate these preclinical findings into a controlled human study setting, aiming to systematically evaluate the therapeutic potential of hUCMSC-derived exosomes for hair regeneration. The study will generate evidence regarding both clinical efficacy and safety profile, providing foundational data for future development of exosome-based regenerative therapies in androgenetic alopecia.

Inclusion Criteria

Participants must meet all of the following criteria to be eligible for enrollment:

1. Male subjects aged 18 to 55 years;
2. Diagnosis of androgenetic alopecia classified as Norwood-Hamilton grade III-V;
3. Stable pattern of hair loss for at least 6 months prior to screening;
4. Willingness to refrain from using any other hair loss treatments during the study period and for 6 months after completion of treatment.

Exclusion Criteria

Participants meeting any of the following criteria will be excluded:

1. Other types of alopecia, including alopecia areata, cicatricial alopecia, or telogen effluvium;
2. Use of minoxidil, finasteride, spironolactone, or other hair growth-related medications within 1 year prior to screening;
3. Receipt of platelet-rich plasma (PRP), laser cap therapy, or other scalp procedures within 6 months prior to screening;
4. History of autoimmune disease, active scalp infection, coagulation disorders, or malignancy;
5. Known hypersensitivity to the investigational product or any of its components;
6. Inability to comply with study procedures, incomplete clinical data, or conditions that may interfere with efficacy evaluation;
7. Participation in another clinical trial within the study period;
8. Any condition that, in the opinion of the investigator, makes the participant unsuitable for the study.

Individual participant data (IPD) sharing has not yet been determined. Data sharing policies will be considered after study completion in accordance with institutional regulations, ethical requirements, and participant privacy protection.