Objective:

To provide a structured, evidence-based narrative review of platelet-rich plasma (PRP), extracellular vesicles/exosomes, and emerging adjunctive therapies in the context of hair transplantation.

Approach:

• Literature Search: A structured literature search was conducted in PubMed/MEDLINE, Scopus, and Google Scholar databases from inception to February 2025, focusing on English-language studies evaluating regenerative therapies in hair loss and hair transplantation.

Key Findings:

• PRP shows moderate to strong evidence in androgenetic alopecia; increases in hair density of approximately 10–30 hairs/cm2 have been reported in randomized trials, but evidence specific to transplantation is limited and heterogeneous.
• Exosome-based approaches show preclinical effects on dermal papillary cell proliferation and angiogenesis, but lack robust clinical validation and standardized characterization.
• Emerging adjuvant therapies, including low-level laser therapy, microneedling-assisted application, and photoactivated PRP, exhibit variable efficacy with limited transplantation-specific data.

Interpretation:

PRP is the most evidence-supported adjuvant therapy in hair transplantation, while exosome-based and emerging regenerative approaches are still under investigation.

Limitations:

• Heterogeneity in preparation protocols and outcome reporting for PRP.
• Limited standardization and variability in sourcing and characterization of exosomes.
• Fragmented evidence base for emerging therapies with significant differences in study design and outcome measures.

Conclusion:

Standardization of protocols, quantitative outcome reporting, and transplantation-specific endpoints are necessary to improve clinical translation and quality of evidence.