Single human sperm cryopreservation method using hollow-core agarose capsules

Abstract

A cryopreservation method for a single sperm using an agarose capsule has been developed. The method is expected to be useful in ICSI treatment in patients with few spermatozoa.

Agarose capsules as new tools for protecting denuded mouse oocytes/embryos during handling and freezing-thawing and supporting embryonic development in vivo

“…Agarose capsules were produced according to the method described in a previous study 13 . Briefly, alginate beads were prepared using 0.5% calcium carbonate and 4% alginate acid solutions.…”

“…Recently, Araki et al . produced an agarose capsule that can be used to store sperm individually 13 . The shape of the agarose capsule is extremely similar to that of the ZP, and it is possible to create a capsule with a ZP-like size.…”

Microfluidics for cryopreservation

“…Additionally, sperm cryopreservation is a critical part of assisted reproductive technology (ART) (Araki et al, 2015; Tomita et al, 2016; Zou et al, 2013), while most of the applications of microfluidics in sperm processing were focused on sorting or isolation of sperm from semen sample; few studies were found on CPA addition and removal (Cho et al, 2003; Huang et al, 2014; Li et al, 2016; Samuel et al, 2016; Sano et al, 2010; Schuster et al, 2003). 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.…”

“…Furthermore, the high surface-area-to-volume ratio of cell suspension on a chip intrinsically enables rapid cooling and warming needed for vitrification. More importantly, this technique provides an urgently needed method for preserving very limited volumes of biological samples, as often occurs with assisted reproductive technologies and stem cell research (Araki et al, 2015; Cohen and Garrisi, 1997; Cohen et al, 1997; Montag et al, 1998; Rao et al, 2015; Wang et al, 2016). Microfluidics can further be used to produce biological agents and cells in micro-scale volumes, enabling low-CPA droplet or encapsulation vitrification (Choi et al, 2015a; He et al, 2008; Huang et al, 2015; Risco et al, 2007; Tasoglu et al, 2013).…”

“…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). Single or a small number of human sperms have been successfully cryopreserved using microcapsules (Araki et al, 2015; Cohen and Garrisi, 1997; Cohen et al, 1997; Montag et al, 1998), and due to the fact that microfluidics is an well-established method for cell encapsulation (Huang et al, 2015; Koster et al, 2008; Zimmermann et al, 2007), we believe that cryopreservation of gamete and embryo on-chip is an emerging technology which will cause extensive attention.…”