Lise Eamer

Bio: Lise Eamer is an academic researcher from University of Toronto. The author has contributed to research in topics: Sperm & Inlet. The author has an hindex of 3, co-authored 5 publications receiving 143 citations.

Rapid selection of sperm with high DNA integrity.

Abstract: Sperm selection is essential to assisted reproductive technology (ART), influencing treatment outcomes and the health of offspring. The fundamental challenge of sperm selection is dictated by biology: a heterogeneous population of ~108 sperm per milliliter with a short lifetime in vitro. However, conventional sperm selection approaches result in less than 50% improvement in DNA integrity. Here, a clinically applicable microfluidic device is presented that selects sperm based on the progressive motility in 500 parallel microchannels. The result is a one-step procedure for semen purification and high DNA integrity sperm selection from 1 mL of raw semen in under 20 minutes. Experiments with bull sperm indicate more than 89% improvement in selected sperm vitality. Clinical tests with human sperm show more than 80% improvement in human DNA integrity, significantly outperforming the best current practices. These results demonstrate the presence of a sub-population of sperm with nearly intact chromatin and DNA integrity, and a simple clinically-applicable lab-on-a-chip method to select this population.

Turning the corner in fertility: high DNA integrity of boundary-following sperm.

Abstract: We present a passive microfluidic sperm selection strategy that collects motile sperm based on their preference to follow boundaries and turn corners. Clinical assessment of selected human sperm from the device revealed a strong correlation between high DNA integrity and the tendency for sperm to follow boundaries. Human sperm with preference to follow boundaries on the left- or right-hand sides have higher (>51%) DNA integrity than straight swimmers and significantly higher (>67%) DNA integrity than sperm in raw semen. Boundary following behaviour offers a strategy to selecting sperm with the highest DNA integrity to improve the success rate of assisted reproduction.

Microfluidic assessment of swimming media for motility-based sperm selection

Abstract: Selection medium is important in sperm isolation for assisted reproductive technologies. Contrary to the naturally occurring human cervical mucus which has a high viscosity, most current practices for motility based sperm selection use a low viscosity medium. In this study, we used a microfluidic device to assess the effects of high viscosity media made with hyaluronic acid (HA) and methyl cellulose (MC) on bovine and human sperm motility and viability (sperm transferred directly from cryoprotectant). The microfluidic penetration test, viability, and motility were compared for sperm swimming in both HA and MC media with about 20cp viscosity (measured at 20 °C). Our resulted indicate that MC medium resulted in a significantly higher number of viable bovine sperm penetrating the medium as compared to HA. Furthermore, MC resulted in the selection of a sperm subpopulation with a 274% increase in sperm viability in comparison to the raw semen, while HA increased viability by only 133%. In addition to viability, bovine sperm motility parameters were significantly higher in the MC medium as compared with HA. Experiments with human sperm swimming in MC indicate that sperm swim slower and straighter at higher viscosities. In conclusion, the results indicate that in a micro-confined environment representative of the in vivo environment, MC is a preferred high viscosity medium to ensure the highest concentration of motile and viable sperm.

Apparatus and methods for sperm separation

Abstract: Various embodiments of methods and apparatuses for separating sperm, including apparatus having an inlet and an outlet reservoir, and either: i) a radial array of microchannels disposed between the inlet and outlet reservoirs to provide fluid communication therebetween and to direct motile sperm inwardly from the inlet reservoir to the outlet reservoir; or ii) at least one microchannel path disposed between the inlet and outlet reservoirs to provide fluid communication therebetween, the at least one microchannel path having a path inlet adjacent the inlet reservoir, a path outlet adjacent the outlet reservoir, and a junction located between the path inlet and the path outlet for directing a portion of sperm that enter the path inlet towards the outlet reservoir based on wall-swimming behavior of sperm. Methods include filling an apparatus with buffer fluid, introducing semen into an inlet reservoir, and retrieving sperm separated from the semen from the outlet reservoir.

Two-dimensional slither swimming of sperm within a micrometre of a surface.

Abstract: Sperm motion near surfaces plays a crucial role in fertilization, but the nature of this motion has not been resolved. Using total internal reflection fluorescence microscopy, we selectively imaged motile human and bull sperm located within one micron of a surface, revealing a distinct two-dimensional (2D) 'slither' swimming mode whereby the full cell length (50-80 μm) is confined within 1 μm of a surface. This behaviour is distinct from bulk and near-wall swimming modes where the flagellar wave is helical and the head continuously rotates. The slither mode is intermittent (∼1 s, ∼70 μm), and in human sperm, is observed only for viscosities over 20 mPa·s. Bull sperm are slower in this surface-confined swimming mode, owing to a decrease in their flagellar wave amplitude. In contrast, human sperm are ∼50% faster-suggesting a strategy that is well suited to the highly viscous and confined lumen within the human fallopian tube.

Microfluidics for sperm analysis and selection

Abstract: Infertility is a growing global health issue with far-reaching socioeconomic implications. A downward trend in male fertility highlights the acute need for affordable and accessible diagnosis and treatment. Assisted reproductive technologies are effective in treating male infertility, but their success rate has plateaued at ∼33% per cycle. Many emerging opportunities exist for microfluidics - a mature technology in other biomedical areas - in male infertility diagnosis and treatment, and promising microfluidic approaches are under investigation for addressing male infertility. Microfluidic approaches can improve our fundamental understanding of sperm motion, and developments in microfluidic devices that use microfabrication and sperm behaviour can aid semen analysis and sperm selection. Many burgeoning possibilities exist for engineers, biologists, and clinicians to improve current practices for infertility diagnosis and treatment. The most promising avenues have the potential to improve medical practice, moving innovations from research laboratories to clinics and patients in the near future.

Acoustic actuation of bioinspired microswimmers

Abstract: Acoustic actuation of bioinspired microswimmers is experimentally demonstrated. Microswimmers are fabricated in situ in a microchannel. Upon acoustic excitation, the flagellum of the microswimmer oscillates, which in turn generates linear or rotary movement depending on the swimmer design. The speed of these bioinspired microswimmers is tuned by adjusting the voltage amplitude applied to the acoustic transducer. Simple microfabrication and remote actuation are promising for biomedical applications.