Expression Level of Prostaglandin D2 Receptor 2 Regulates Hair Regression

In a 2019 study, researchers discovered that the prostaglandin D2 receptor 2 (DP2 receptor) is highly expressed during the early catagen phase of the hair cycle in mice, a period when hair follicles start to regress. They demonstrated that reducing DP2 receptor expression in human hair follicles through siRNA could inhibit the transition from the growth phase (anagen) to the regression phase (catagen), indicating the receptor's role in hair growth inhibition. Furthermore, cells from the outer root sheath (ORS) and dermal papilla (DP) of patients with male pattern baldness showed increased levels of DP2 receptor expression compared to those from non-balding individuals. These results imply that the PGD2-DP2 receptor pathway might be a potential target for hair loss prevention treatments. However, the exact number of human samples used in the study was not mentioned in the summary.