Reprogramming efficiency and pluripotency of mule iPSCs over its parents†

The mule is the interspecific hybrid of horse and donkey and has hybrid vigor in muscular endurance, disease resistance, and longevity over its parents. Here, we examined adult fibroblasts of mule (MAFs) compared with the cells from their parents (donkey adult fibroblasts and horse adult fibroblasts) (each species has repeated three independent individuals) in proliferation, apoptosis, and glycolysis and found significant differences. We subsequently derived mule, donkey, and horse doxycycline (Dox)-independent induced pluripotent stem cells (miPSCs, diPSCs, and hiPSCs) from three independent individuals of each species and found that the reprogramming efficiency of MAFs was significantly higher than that of cells of donkey and horse. miPSCs, diPSCs, and hiPSCs all expressed the high levels of crucial endogenous pluripotency genes such as POU class 5 homeobox 1 (POU5F1, OCT4), SRY-box 2 (SOX2), and Nanog homeobox (NANOG) and propagated robustly in single-cell passaging. miPSCs exhibited faster proliferation and higher pluripotency and differentiation than diPSCs and hiPSCs, which were reflected in co-cultures and separate-cultures, teratoma formation, and chimera contribution. The establishment of miPSCs provides a unique research material for the investigation of heterosis and perhaps is more significant to study hybrid gamete formation. We found that mule adult fibroblasts have significant advantages in reprogramming efficiency compared with donkey and horse adult fibroblasts, and the establishment of mule iPSCs provides an accessible in vitro model to study hybrid gamete formation.

Automated summary

This study found significant differences in proliferation, apoptosis, and glycolysis between adult fibroblasts of mules, donkeys, and horses. The reprogramming efficiency of mule fibroblasts was significantly higher than that of donkey and horse cells. The establishment of mule induced pluripotent stem cells (miPSCs) provides a unique research material for studying hybrid gamete formation.