Can we Make SpermFAST? Improving Sperm Function to Increase Fertilisation Rates after in vitro Fertilisation

Abstract

Background: Intracytoplasmic sperm injection (ICSI) usage ([Formula: see text]64% of autologous cycles) has increased in Australia as an attempt to avoid low fertilisation and total fertilisation failure after standard in vitro fertilization (IVF). ICSI and to a lesser extent IVF, bypass key sperm maturation (hyperactivation, capacitation/acrosome reaction) events that naturally occur in the female tract and are vital for successful fertilisation. Current commercial sperm preparation media are not fully designed to induce these changes in sperm prior to insemination. Aim: To improve fertilisation rates following IVF by increasing sperm capacitation and hyperactivation between sperm preparation and insemination ultilising a new sperm medium (SpermFAST). Method: Sperm from 12 consenting normospermic men were incubated in either G-IVF+ (Vitrolife) or SpermFAST (UoA/Monash IVF) following a direct swim-up. Measures of capacitation, hyperactivation, sperm binding, acrosome reaction and oxidative DNA damage were assessed. Further, sperm from male CBAF1 mice (N=8) were incubated in either G-IVF+ or SpermFAST prior to IVF insemination. Fertilisation rates, embryo development, blastocyst cell numbers and DNA damage were assessed. Results: Incubation of human sperm in SpermFAST increased tyrosine phosphorylation (15.8% vs 9.5%, P[Formula: see text]0.05), hyperactive motility (38.3% vs 14.9%, P[Formula: see text]0.01), sperm binding (73.1% vs 47.7%, P[Formula: see text]0.01), while having no impact on sperm acrosomal status or oxidative DNA damage levels. Following IVF in the mouse, sperm incubated in SpermFAST increased fertilisation rates (94% vs 88%, P[Formula: see text]0.05), blastocyst total cell (92.2% vs 77.4%, P[Formula: see text]0.05), inner cell mass (14.9% vs 18.9%, P[Formula: see text]0.01) and epiblast cell numbers (3.7% vs 1.6%, P[Formula: see text]0.01), while the proportion of DNA damaged cells decreased in blastocysts (2.3% vs 4.8%, P[Formula: see text]0.001). Conclusion: Sperm function and fertilisation rates are improved when the sperm medium better mimics the environment of the female reproductive tract during natural conception. Improving IVF culture media to better meet the physiological needs of sperm could potentially improve outcomes following IVF.