PROM1 and hydrops fetalis: To date, due to the lack of genetic tools that can be used to isolate CD133− DP cells, the biological differences between CD133 + and CD133− DP cell populations in terms of DP characteristics and HF neogenesis have remained unclear, hindering efforts to uncover the key driving force in the DP that orchestrates their reciprocal interactions with keratinocytes to generate HFs.