Microfluidics and numerical simulation as methods for standardization of zebrafish sperm cell activation

Abstract

Sperm cell activation plays a critical role in a range of biological and engineering processes, from fertilization to cryopreservation protocol evaluation. Across a range of species, ionic and osmotic effects have been discovered that lead to activation. Sperm cells of zebrafish (Danio rerio) initiate motility in a hypoosmotic environment. In this study, we employ a microfluidic mixer for the purpose of rapidly diluting the extracellular medium to initiate the onset of cell motility. The use of a microchannel offers a rapid and reproducible mixing profile throughout the device. This greatly reduces variability from trial to trial relative to the current methods of analysis. Coupling these experiments with numerical simulations, we were able to investigate the dynamics of intracellular osmolality as each cell moves along its path through the micromixer. Our results suggest that intracellular osmolality, and hence intracellular ion concentration, only slightly decreases, contrary to the common thought that larger changes in these parameters are required for activation. Utilizing this framework, microfluidics for controlled extracellular environments and associated numerical modeling, has practical applicability in standardizing high-throughput aquatic sperm activation, and more fundamentally, investigations of the intracellular environment leading to motility.

Designing 3-Dimensional In Vitro Oviduct Culture Systems to Study Mammalian Fertilization and Embryo Production

“…Research into microfluidics and reproductive events have increased in the past years, and relatively new papers on microfluidics and gamete development have been published 4,15,20,21,24,31,41,42,52,56,62,78,99,111,121,124. In most cases, these papers relate to sperm migration, and none have included OECs in the model.…”

Microfluidics for cryopreservation

“…Fortunately, both the designs for the staggered herringbone microfluidic mixer (Park et al, 2012) and the passive, planar micromixer based on logarithmic spirals (Scherr et al, 2015; Scherr et al, 2012) (Figure 7E), which are initially developed for sperm activation, can be potentially adopted for CPA processing, since where controllable extracellular mixing is supplied.…”

“…Significant progress has been made in recent years for application of microfluidics in ART, e.g., sperm activation, sorting and isolation, oocyte processing, fertilization, and embryo culture (Cho et al, 2003; de Wagenaar et al, 2016; Huang et al, 2014; Li et al, 2016; Ohta et al, 2010; Samuel et al, 2016; Sano et al, 2010; Scherr et al, 2015; Schuster et al, 2003; Suh et al, 2003; Tsai et al, 2010; Zhang et al, 2011b). As an important and indispensable part of fertility preservation, cryopreservation on-chip has also achieved considerable progress, e.g., on-chip CPA-free cryopreservation of small amounts of human spermatozoa was successfully accomplished (Zou et al, 2013).…”

“…(E) A sequential logarithmic microfluidic mixer for zebrafish sperm activation. Reproduced from (Bala Chandran et al, 2012; Lusianti and Higgins, 2014; Scherr et al, 2013; Song et al, 2009)(Scherr et al, 2015) with permission.…”

Three-dimensional printing with polylactic acid (PLA) thermoplastic offers new opportunities for cryobiology

“…Three-dimensional printing has offered tremendous opportunities to other fields such as medical prosthetics where designs requiring custom fit can be created from scanned patient body geometries, inexpensively printed, and fitted to the end user [7]. Similarly for cryogenic applications, 3-D printing can accelerate progress in development of custom devices for handling, sorting, freezing, and storage of cryobiological samples as has been seen for technologies such as microfabrication [9]. 3-D printers continue to advance in capability and decrease in cost, and are now affordable for individual laboratories (~$2,500) and should receive greater attention in cryobiology research and application.…”