Can Hyaluronidase PH-20 in Embryo Culture Medi-um Improve Developmental Competence of Ovine Oocytes

Background: Hyaluronic acid (HA) plays an important role in regulating various reproductive events. There are different results from supplementation of embryo in vitro culture (IVC) medium with HA. Instead of using HA in IVC, supplementa-tion of IVC with HA system components, including hyaluro-nan synthases (HAS), HA-degrading enzymes (hyaluronidases; HYALs) and HA receptors (HAS) is of great importance and should be investigated. PH-20, is a hyaluronidase, present in spermatozoa and degrade HA into pieces of tetra-saccharide that may play an important role in cell proliferation and mitosis. Therefore, in this study we evaluated the effect of supplementa-tion of IVC medium with two type of HYALs: human recombi-nant PH-20 produced at Royan institute (rhPH-20) and PH-20 sigma (sPH-20) on early embryonic development in terms of blastocyst rate.Materials and Methods: Cumulus-oocyte complexes (COCs) were retrieved from sheep slaughtered ovaries. Selected COCs were cultured in maturation medium. Briefly, after 22–24 hours of maturation, oocytes were fertilized using fresh semen and in-cubated for 18 to 21 hours. Then, denuded presumptive zygotes were divided into three group: two groups with 300 unit/ml of rhPH-20 and purified HYALs from testis from sigma company (sPH-20) and their control counterpart.Results: Our results demonstrated a significant decrease (P< 0.05) in blastocyst rate in both treatment groups (rhPH-20 and sPH-20) (16.38 ± 3.06 and 16.11 ± 3.94, respectively) in compare to control group at and (27.53 ± 3.56).Conclusion: Our data revealed that supplementation of IVC medium with either rhPH-20 or sPH20 couldn t improve blas-tocyst rate in contrast to similar studies. Previous studies used hyaluronidase 2 and found significant improvement in produc-tion of blastocyst in cattle. This difference may be raised from different type of HYALs which we used in this study in com-pare to previous studies. Previous studies used hyaluronidase 2 and may be its product (20 kDa HA) has an efficient impact on embryonic development, which probably connects the product to the CD44 receptor, which can effectively guide the signaling pathways, while in this study we used PH-20 which is similar to hyaluronidase 1 and its product is approximately 0.8 kDa which may have lower interaction with CD44 receptor. In ad-dition previous studies also showed that hyaluronidase 1 has lower expression in compare to hyaluronidase 2 at morula to blastocyst stage. Therefore, using hyaluronidase 2 instead of hyaluronidase 1in IVC medium may promote the developmen-tal competence of ovine oocytes which needs more investiga-tions to be elucidated.

کلیدواژه ها:

Hyaluronic Acid System ، Hyaluronidase PH-20 ، Ovine ، Embryonic Development