Differential Gene Expression of Mesenchymal Stromal Cell and Granulosa Cell Markers in Equine Follicular Aspirates

ABSTRACT Equine follicular aspirates obtained during ovum pick‐up contain a heterogeneous mixture of mesenchymal stromal cells (MSC) and granulosa cells (GC). This study evaluates how selective isolation and expansion of MSC decrease GC populations. Follicular aspirates‐derived cells were cultured up to passage four (P4) following a previously validated protocol. While freshly isolated follicular aspirates cells (FAC) displayed heterogeneous morphologies, early passages (P3‐P4) showed a uniform, spindle‐shaped phenotype compatible with MSC. Gene expression analysis by RT‐qPCR revealed a marked upregulation of mesenchymal and stemness‐associated genes ( FN1, THY1, FGF2 and CD105 ) in P4‐MSC compared with FAC, confirming enrichment of the MSC population. Conversely, GC‐specific genes ( FSHR, FOXL2 and CYP11A1 ) were significantly upregulated in FAC. These findings suggest that early passages efficiently promote selective MSC expansion while progressively eliminating GC.