Studying Beating Characteristics of Bovine Sperm cells using Microfluidics

A Master of Science thesis in Biomedical Engineering by Aisha Hamidu entitled, “Studying Beating Characteristics of Bovine Sperm cells using Microfluidics”, submitted in December 2022. Thesis advisor is Dr. Mohamed Abdelgawad. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).

Abstract

Infertility is a serious global health problem affecting 8-12% of couples worldwide. Both men and women are responsible with nearly half of the infertility cases due to the male factor. Although male infertility can be attributed to various causes such as varicocele, genetic abnormalities and immunological factors, there is a high level of unknown factors in male infertility. This serves as a challenge due to the lack of understanding of these underlying mechanisms and not knowing the factors that are causing infertility in men. Analyzing the ability of sperm cells to reach and fertilize an oocyte is important in defining new factors that can explain the unexplained infertility cases and their causes. The spermatozoa journey from the cervix to the oviducts where fertilization takes place is a complex one and studying it is crucial for exploring new causes of male infertility. Any abnormality that befalls the sperm during its transport within the biophysical and biochemical environment of the human female reproductive tract may result in infertility. In this current study, high speed imaging analysis was used to study the beating pattern of immobilized bovine sperm cells flagellum under different chemical stimuli (Caffeine and Heparin) and physical stimuli (flow and no flow conditions). Bovine sperm cells where immobilized on islands of fibronectin deposited on glass slides using microcontact printing before being subjected to chemical and physical stimuli. Following stimulation with Caffeine, the analysed cells exhibited a decreased beat frequency of 25.07 ± 3.02, 22.08 ± 4.03, and 19.47 ± 2.01 Hz at the three tested concentrations compared to control frequency of, 33.15 ± 10.84 Hz. Heparin had an opposite effect of increasing the frequency to 41.26 ± 4.58 Hz. Both stimulants caused an increase in the flagellum beating amplitude. When sperm cells were subjected to a continuous flow velocity of 100 μm/s, it was noticed that the beating frequency decreased significantly from 33.15 Hz to 16.94 Hz. These results show the heterogenous behaviour of Bovine sperm cells under the different conditions that may exist in the female reproductive tract.