1343 Efficacy of asymmetric siRNA targeting androgen receptor for the treatment of androgenetic alopecia

Asymmetric small interfering RNA (asiRNA) that induces RNA interference has been investigated for its therapeutic use in various tissues, including the skin. Androgenetic alopecia (AGA) is caused by a combination of genetic factors resulting in sensitivity to dihydrotestosterone (DHT), which binds to the androgen receptor (AR) to induce a series of biomolecular changes leading to hair loss. This study aimed to evaluate the therapeutic potential of a cell penetrating, AR-targeting asiRNA (cp-asiAR), which was designed to silence the AR gene, for AGA treatment. AGA mouse models were generated by stimulation with DHT, and ex vivo human scalp tissues were also used. Cp-asiAR-mediated changes in AR mRNA expression and protein level were assessed together with phenotypic improvement in hair loss. We also assessed AR downstream signaling in primary human dermal papilla (DP) cells. Several cp-asiARs were screened for selecting the optimal sequence for AR using cell lines in vitro. A cholesterol-conjugated, chemically modified cp-asiAR candidate was optimized under passive uptake conditions in vitro. Intradermal cp-asiAR injection efficiently reduced AR mRNA and protein levels in mouse models. Moreover, cp-asiAR injection promoted hair growth in DHT-induced AGA mouse models. In ex vivo human hair follicle culture, the proportion of telogen hair decreased, and the mean hair bulb diameter increased in the cp-asiAR-treated group. In isolated primary human DP cells, AR expression in DP cells was effectively downregulated by cp-asiAR. Concurrently, cp-asiAR attenuated DHT-induced increases in interleukin-6, transforming growth factor-β1, and dickkopf-1 levels. No significant toxicity was observed in DP cells after cp-asiAR treatment. Effective downregulation of AR expression and prevention of DHT-induced changes in the hair cycle and hair diameter were achieved using cp-asiAR treatment, indicating its potential as a novel therapeutic option for AGA.