Procyanidin Oligomers Selectively and Intensively Promote Proliferation of Mouse Hair Epithelial Cells In Vitro and Activate Hair Follicle Growth In Vivo11The authors disclosed conflict of interest.

In a study from 1999, researchers found that procyanidin oligomers, specifically procyanidin B-2 (a dimer) and procyanidin C-1 (a trimer), derived from grape seeds, significantly promoted the proliferation of mouse hair epithelial cells in vitro and stimulated hair growth in vivo. The procyanidin B-2 showed a maximum growth-promoting activity of about 300% at a concentration of 30 microM, while procyanidin C-1 reached about 220% at 3 microM, compared to control levels set at 100%. These compounds were more effective than other flavonoid compounds tested. The study also demonstrated that only epithelial cells, such as hair keratinocytes, responded to procyanidin oligomers. When applied topically at 1% concentration to C3H mice in the telogen phase of hair growth, procyanidin oligomers significantly induced hair regeneration, with procyanidin B-2 achieving 69.6% ± 21.8%, procyanidin B-3 achieving 80.9% ± 13.0%, and procyanidin C-1 achieving 78.3% ± 7.6% hair regrowth on the shaven area, compared to a 41.7% (SD = 16.3%) regrowth with the vehicle only. This study suggested the potential of procyanidin oligomers as agents to induce hair growth.