Production of Gelatinases and Tissue Inhibitors of Matrix Metalloproteinases by Equine Ovarian Stromal Cells

Matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs) play very important roles in extracellular matrix (ECM) remodeling in ovarian follicle growth and ovulation. Equine follicles are embedded in cortex that is at the center of the ovary, and they must expand/emigrate to the fossa, the only site in the ovary for ovulation. Therefore, equine ovarian stromal cells (EOSC) are probably involved in ECM remodeling during follicle growth. This study examined whether cultured EOSC synthesize gelatinases and TIMPs, molecules essential for ECM remodeling in other systems. Results showed that cultured EOSC (passage 3–8) had a fibroblast-like morphology and were posi-tive for a-smooth muscle actin and type I procollagen by im-munostaining. Gelatinase A (MMP-2), gelatinase B (MMP-9), TIMP-1, and TIMP-2 were present in EOSC-conditioned medi-um, and TIMP-3 in ECM of EOSC. Transforming growth factor b significantly stimulated the activity of gelatinases A and B and TIMP-1 in conditioned medium from EOSC (p, 0.05). Phorbol 12-myristate 13-acetate also significantly stimulated the activity of gelatinases A and B and TIMP-1 in conditioned medium and of TIMP-3 in ECM (p, 0.05). Our results suggest that EOSC produce important components of the ECM remodeling machin-ery and, therefore, may play a role in the ECM remodeling dur-ing follicle growth in this species