MKI67 and hydrops fetalis: Optimal cooling at 18°C rescued cell viability, significantly (p < 0.001) restored HF proliferation (42% Ki-67+ cells) and pigmentation, suppressed apoptosis (10% TUNEL+ cells), restored anagen (∼70%) and induced a 2-3-fold increase in hair shaft elongation (p < 0.001), whereas cooling at 26°C was only partially effective.