Prediction of sperm progression in three dimensions using rapid optical imaging and dynamic mechanical modeling

Abstract

We present a multidisciplinary approach for predicting how sperm cells with various morphologies swim in three-dimensions (3D), over time scales of milliseconds to hours at spatial resolutions of less than half a micron. We created the sperm 3D geometry and built a numerical mechanical model using the experimentally acquired dynamic 3D refractive index profiles of sperm cells swimming freely in vitro as imaged by high-resolution optical diffraction tomography. By controlling parameters in the model, such as the size and shape of the sperm head and tail, we can then predict how different sperm cells, normal or abnormal, would swim in 3D, in the short or long term. We quantified various 3D structural factor effects on the sperm long-term motility. We found that some abnormal sperm cells swim faster than normal sperm cells, in contrast to the commonly-used sperm selection assumption during IVF, according to which sperm cells should mainly be chosen based on their progressive motion. We established a new tool for sperm analysis and male-infertility diagnosis, as well as new sperm selection criteria for fertility treatments.

Evaluation of women’s aging influence on sperm passage inside the fallopian tube using 3D dynamic mechanical modeling

“…Most of the 3D trajectories of the normal sperm models were close to the fallopian tube walls near the internal longitudinal folds of the mucosal layer. Our findings match the results of previous studies about tracking healthy human sperm cells (Chenoweth, 2005;Su et al, 2012;Dardikman-Yoffe et al, 2020;World Health Organization, 2021;Nassir et al, 2022;Nassir et al, 2023) and sperm cell-to-surface interactions (Guidobaldi et al, 2015;Rode et al, 2019;Zaferani et al, 2021). For all age groups, most of the normal sperm models accumulated in the intramural and isthmus regions due to the small luminal area.…”

“…For all ages, we observed that the normal sperm models moved forward inside the fallopian tube with a small lateral displacement. This swimming behavior is equivalent to the swimming pattern of the normal sperm cells reported in previous bio-mechanical, microfluidic, and experimental imaging studies of human sperm cell motility (Chenoweth, 2005;Su et al, 2012;Sartori et al, 2016;Rode et al, 2019;Dardikman-Yoffe et al, 2020;World Health Organization, 2021;Nassir et al, 2022Nassir et al, , 2023. Figure 4 shows that most of the normal sperm models accumulated in the intramural and isthmus regions due to the small luminal area.…”

“…We used the 3D geometrical models of the normal and abnormal sperm cells developed in our previous study (Nassir et al, 2022;. We built a numerical mechanical sperm model based on previous dynamic 3D optical imaging experimental results of sperm cells done by our group (Dardikman-Yoffe et al, 2020).…”

“…Frontiers in Bioengineering and Biotechnology frontiersin.org sperm cells swimming close to walls (Chenoweth, 2005;Su et al, 2012;Dardikman-Yoffe et al, 2020;World Health Organization, 2021;Nassir et al, 2022;Nassir et al, 2023).…”

“…In the current study, using a unique combination of simulative tools, we developed a mechanical model of sperm-cell swimming behavior within the human fallopian tube in different age groups and analyzed the women's aging effects on the chances of normal and pathological sperm cells reaching the fertilization site. We used the 3D detailed geometrical models of the normal and pathological sperm cells developed in our previous studies (Nassir et al, 2022;, but simplified the 3D geometry of the sperm models, including the external sperm cell real organs (head, flagellum, and midpiece) to allow dynamic 3D simulation of many sperm cells swimming together in the woman's body. The pathological sperm models include frequent defects in the sperm head and flagellum morphologies appearing in WHO-2021guidelines (World Health Organization, 2021.…”