title: Hyaluronan and hyaluronidase, which is better for embryo development?
abstract: Our aim was to examine size-specific effects of Hyaluronan (HA) on preimplantation embryo development. We investigated the effects of Hyalovet (HA, 500-750 kDa; the size produced by HA synthase-3, which is abundant in the oviduct), or HA treated with Hyaluronidase-2 (Hyal2; also expressed in the oviduct that breaks down HA into 20 kDa fragments). In experiment 1 (in vivo), oviducts of synchronized and superovulated ewes (n = 20) were surgically exposed on Day 2 post-mating, ligated, and infused with either Hyalovet, Hyalovet + Hyal2, Hyal2, or PBS (control). Ewes were killed 5 days later for recovery of embryos and oviductal epithelial cells (OEC). Blastocyst rates were significantly higher in Hyal2 and Hyalovet + Hyal2 oviducts. Hyaluronidase-2 infusion resulted in higher blastocyst cell numbers and hatching rates. This was associated with increased HSP70 expression in OEC. In contrast, Hyalovet resulted in the lowest development to blastocyst stage and lowest hatching rates, and decreased IGF2 and IGFBP2 expression in OEC. IGF1 and IL1α expression were not affected. In experiment 2, to rule out indirect effects of oviductal factors, ovine embryos were produced and cultured with the same treatments in vitro from Day 2 to 8. Hyaluronidase-2, but not Hyalovet, enhanced blastocyst formation and reduced inner cell mass apoptosis. Hyalovet inhibited hatching. In conclusion, the presence of large-size HA (500-750 kDa) in the vicinity of developing embryos appears to disturb the oviductal environment and embryo development in vivo and in vitro. In contrast, we show evidence that breakdown of HA into smaller fragments is required to maximize embryo development and blastocyst quality.
authors.affiliation: Reproduction and Development Research Group, Department of Comparative Biomedical Sciences, Royal Veterinary College, Hatfield, Herts, UK; Department of Theriogenology, Faculty of Veterinary Medicine, Cairo University, Giza, Egypt.
authors.forename: Waleed F A
authors.initials: WFA
authors.lastname: Marei
authors.affiliation: Reproduction and Development Research Group, Department of Comparative Biomedical Sciences, Royal Veterinary College, Hatfield, Herts, UK; Department of Veterinary Surgery and Theriogenology, Michael Okpara University of Agriculture, Umudike, Nigeria.
authors.forename: Kabir A
authors.initials: KA
authors.lastname: Raheem
authors.affiliation: Reproduction and Development Research Group, Department of Comparative Biomedical Sciences, Royal Veterinary College, Hatfield, Herts, UK.
authors.forename: Mazdak
authors.initials: M
authors.lastname: Salavati
authors.affiliation: Reproduction and Development Research Group, Department of Comparative Biomedical Sciences, Royal Veterinary College, Hatfield, Herts, UK.
authors.forename: Tina
authors.initials: T
authors.lastname: Tremaine
authors.affiliation: Reproduction and Development Research Group, Department of Comparative Biomedical Sciences, Royal Veterinary College, Hatfield, Herts, UK.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Khalid
authors.affiliation: Reproduction and Development Research Group, Department of Comparative Biomedical Sciences, Royal Veterinary College, Hatfield, Herts, UK. Electronic address: afouladi@rvc.ac.uk.
authors.forename: Ali A
authors.initials: AA
authors.lastname: Fouladi-Nashta
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D001755:Blastocyst / Q000187:drug effects*; D005187:Fallopian Tubes; D005260:Female; D018507:Gene Expression Regulation, Developmental; D006820:Hyaluronic Acid / Q000008:administration & dosage / Q000494:pharmacology*; D006821:Hyaluronoglucosaminidase / Q000008:administration & dosage / Q000494:pharmacology*; D012756:Sheep / Q000196:embryology*; D013480:Superovulation; D020858:Tissue and Organ Harvesting
chemical_list: D000276:Adjuvants, Immunologic; D006820:Hyaluronic Acid; D006821:Hyaluronoglucosaminidase
keywords: Blastocyst; HSP70; Hyaluronidase-2; IGF; IL1α