Hyaluronan and hyaluronidase, which is better for embryo development?

Area of Science:

• Reproductive Biology
• Developmental Biology
• Biochemistry

Background:

• Hyaluronan (HA) is abundant in the oviduct and plays a role in reproductive processes.
• The size of HA molecules may influence its biological activity.
• Understanding HA's role is crucial for improving assisted reproductive technologies.

Purpose of the Study:

• To investigate the size-specific effects of Hyaluronan (HA) on preimplantation ovine embryo development.
• To determine whether large HA fragments (500-750 kDa) or smaller fragments (20 kDa) differentially affect embryo development in vivo and in vitro.
• To explore the molecular mechanisms underlying HA's effects on oviductal epithelial cells (OECs) and embryo quality.

Main Methods:

• Experiment 1 (in vivo): Ovine oviducts were infused with different sizes of HA or PBS, and embryo development was assessed.
• Experiment 2 (in vitro): Ovine embryos were cultured with different HA treatments to isolate direct effects.
• Gene expression analysis (HSP70, IGF2, IGFBP2) in OECs was performed.

Main Results:

• Large HA (Hyalovet) impaired blastocyst formation and hatching rates in vivo and in vitro.
• Smaller HA fragments (Hyaluronidase-2 treated) improved blastocyst rates, cell numbers, and hatching.
• Hyaluronidase-2 treatment increased HSP70 expression and reduced inner cell mass apoptosis, while Hyalovet decreased IGF2 and IGFBP2 expression in OECs.

Conclusions:

• Large-sized HA (500-750 kDa) negatively impacts ovine embryo development in the oviductal environment.
• Breakdown of HA into smaller fragments by Hyaluronidase-2 is essential for optimal embryo development and blastocyst quality.
• Size-specific modulation of HA may be a therapeutic target for improving reproductive outcomes.