High-Throughput Rheotaxis-Based Sperm Separa-tion Using A Simple Microfluidic Device

Background: Human infertility affects almost 200 million people worldwide, and nearly one-third of these population are male related. Several technologies offer to assist the reproduc-tion cycle, and in all of them, the most crucial part which con-trols the success rate is sperm sorting and selection process. Current clinical solutions for sperm sorting and selection have faced few problems through the years; especially they fall short when sorting for sperm free of reactive oxygen species, DNA damage, and epigenetic aberrations. Hence, recently microflu-idic systems have attracted researcher’s attention due to their numerous capabilities, for sperm selection purposes. So far, several microfluidic platforms have succeeded in the selection process, but often they are not straightforward to use or fabri-cate which prevents them from clinical adoption. Inspired by the natural physics of female reproductive tract and spermʼs rheotaxis behavior, a novel microfluidic system was designed to fulfill the needs for sperm sorting and separation. This device takes advantages of oval-shaped microgrooves to optimize the shear stress acting on sperms and to create rheotaxis zones for the separation of highly motile spermsMaterials and Methods: It has been confirmed that in the absence of the flow or when the shear rate is below a critical value, sperms swim in all directions but if the shear rate exceeds the critical value, they were seen to reorient and swim against the flow. Based on these observations and researches and by the use of a finite-element method simulation, we investigated how flow can provide a rheotaxis zone in a microchannel and how to use that as a lever to separate sperms with different motili-ties. By imitating the microgrooves existed on the uterine wall, a microfluidic system featuring oval-shaped microgrooves that efficiently and noninvasively isolates highly motile and mor-phologically normal sperm, with lower epigenetic global meth-ylation, from raw semen, is presented.Results: The primary tests show that comparing to conventional methods the device is simple to use, requires only a small amount of semen, has a high throughput and the processing time of 15 minutes. Also, since the whole process is passive, in further experiments, we expect to see great improvements in DNA integrity and morphology of the sample.Conclusion: The proposed system shows to be a promising substitute for conventional techniques.

کلیدواژه ها:

Sperm-Separation ، DNA-Fragmentation ، Rheotaxis ، Microfluidics