Viscous Cervical Environment-on-a-Chip for Selecting High-Quality Sperm from Human Semen.

Manhee Lee,Seungki Lee,Jung Kyu Choi,Dae Keun Kim,Min Jeong Cho,Dongwon Kim,Do Gyeung Byeun,Jin Woo Park,Jae Ho Lee,Tai Eun Shin,Jung Jae Ko,Eun Ji Lee,Hyojeong Kwon

doi:10.3390/biomedicines9101439

Manhee Lee, Seungki Lee + Show 11 more

Open Access

https://doi.org/10.3390/biomedicines9101439

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Abstract

When ejaculated sperm travels through the vagina to the uterus, mucus secreted by the cervical canal generally filters out sperm having low motility and poor morphology. To investigate this selection principle in vivo, we developed a microfluidic sperm-sorting chip with a viscous medium (polyvinylpyrrolidone: PVP) to imitate the biophysical environment mimic system of the human cervical canal. The material property of the PVP solution was tuned to the range of viscosities of cervical mucus using micro-viscometry. The selection of high-quality human sperm was experimentally evaluated in vitro and theoretically analyzed by the convection-diffusion mechanism. The convection flow is shown to be dominant at low viscosity of the medium used in the sperm-sorting chip when seeded with raw semen; hence, the raw semen containing sperm and debris convectively flow together with suppressed relative dispersions. Also, it was observed that the sperm selected via the chip not only had high motilities but also normal morphologies and high DNA integrity. Therefore, the biomimetic sperm-sorting chip with PVP medium is expected to improve male fertility by enabling the selection of high-quality sperm as well as uncovering pathways and regulatory mechanisms involved in sperm transport through the female reproductive tract for egg fertilization.

Highlights

Licensee MDPI, Basel, Switzerland.Assisted reproductive technologies (ARTs) have helped in the birth of approximately5 million babies since the first reported birth from in vitro fertilization (IVF) in 1978 in England, and these numbers are rapidly increasing each year [1]
The female reproductive tract is represented in Figure 1A; from the vagina to cervix, followed by a semielliptic path to the fallopian tube through the uterus
A drop of raw semen was seeded at the inlet of the sperm-sorting chips (SSCs), and a drop of the sorted solution was collected at the outlet after approximately 40 min; this solution was subsequently investigated for sperm motility, head vacuole, and DNA fragmentation

Summary

Introduction

5 million babies since the first reported birth from in vitro fertilization (IVF) in 1978 in England, and these numbers are rapidly increasing each year [1]. ARTs such as IVF and intracytoplasmic sperm injection (ICSI) have become effective treatment options for infertile couples [2]. Biomedicines 2021, 9, 1439 indicating a very limited birth rate in current clinical practice of ARTs. Male infertility accounts for approximately 30–50% of the total cases of infertility, with infertile men having increased tendencies for abnormal morphologies, low concentrations, poor motilities, and elevated levels of DNA damage in their sperm [3].

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