Colloids: Applications in Sperm Preparation for Assisted Reproduction

Abstract

Colloids have been used for several decades to prepare spermatozoa for assisted reproduction, initially for in vitro fertilization but, with the development of scaled-up techniques, increasingly for artiicial insemination and cryopreservation as well. The colloids usually consist of coated silica particles. Using colloid centrifugation, it is possible to select sperm subpopulations consisting of motile spermatozoa with intact membranes, stable DN" and normal morphology and to separate them from the rest of the ejaculate. This review explains why diferent protocols for colloid centrifugation are needed for diferent species, as well as species-speciic colloid formulations, to match the physical characteristics of the semen. The advantages and disadvantages of sperm preparation by this technique will be outlined. "n emerging area of interest is the ability to separate spermatozoa from the bacteria that contaminate semen during collection. Thus, colloid centrifugation represents an alternative to using antibiotics in semen extenders. Since there is a worldwide movement to restrict the use of antibiotics, the possibility of physically removing the bacteria is of considerable interest. Moreover, it may be possible to use colloids to reduce viruses in semen. Transmission of viruses through semen is an emerging problem as more and more viruses are being identiied that can potentially be spread in this manner.Keywords: sperm quality, single layer centrifugation, antimicrobial resistance . Introduction "ssisted reproduction is the creation of a pregnancy by a means other than natural mating [ ].The most widely used form of assisted reproduction in animals is artiicial insemination "I in vitro fertilization IVF and intracytoplasmic sperm injection ICSI are conined to specialist laboratories, for example, for bovine IVF, or are used occasionally for research or for conservation breeding. In contrast, human fertility treatments usually involve either IVF or ICSI. However, there are many diferences between species regarding sperm numbers needed for "I, the type of semen used fresh, stored or cryopreserved , the timing relative to ovulation, and site of deposition of the semen. These diferences create a range of challenges for sperm preparation according to the species concerned. Despite the diferences, one feature common to all species is that the chance of a successful outcome, that is, a pregnancy, is related to the quality of the sperm sample used. Colloid centrifugation can be used to select good quality spermatozoa for assisted reproduction [ ].The purpose of this review is to describe colloid centrifugation through species-speciic colloids, particularly single layer centrifugation SLC , to select functional spermatozoa. In this review, the history of single layer centrifugation SLC will be presented, the method of preparing semen will be explained and its applications in the semen industry will be proposed. "part from describing the necessity for species-speciic protocols, this review will also look at species-s...

Nanotechnology-based approach for safer enrichment of semen with best spermatozoa

“…Therefore, the use of silane- and polyvinylpyrrolidone-coated colloid silica in density (DLC) and single (SLC) layer centrifugation protocols has revealed beneficial for selecting high quality spermatozoa [23–26], through the purification of high sperm number per analysis (i.e., up to 100 × 10 6 boar spermatozoa). However, the molecular mechanism of the SLC technique remains unclair [23], and its cost and low recovery yield may limit routine applications in swine farms [24, 27]. Recent studies have reported the use of conjugated magnetic nanoparticles as novel tools for molecular-based selection of spermatozoa regardless of the species [28–30].…”

Novel agents for sperm purification, sorting, and imaging

“…Different strategies were adopted to select the best spermatozoa within an ejaculate through targeted elimination of poor‐quality or damaged spermatozoa. Such techniques range from simple differential migration of spermatozoa, called the swim‐up assay (Chen et al, ; Mahadevan & Baker, ; Mortimer, ; Mortimer & Mortimer, ), to more complicated procedures based on density gradient centrifugation (e.g., albumin density (Ericsson, Langevin, & Nishino, ), or polyvinylpyrrolidone‐ and silane‐coated silica colloid solutions, such as Percoll™ and PureSperm®, respectively (Kaneko et al, ; Lessley & Garner, ; Morrell, )); filtration (glass wool (Paulson & Polakoski, ; Van der Ven et al, ), sephadex gel (Steeno, Adimoelja, & STEENO, ), or membrane (Agarwal, Manglona, & Loughlin, ); and microfluidic devices (Li et al, ; Shirota et al, ; Suarez & Wu, ). These purification procedures yield pure and high‐quality spermatozoa (motile and morphological normal) from both humans and animals, but the observed low and highly variable recovery efficiencies (10% to 63%), additional labor, and time‐consumption (>60 min) limit their utility to small‐scale applications (i.e., in vitro fertilization and intracytoplasmic sperm injection).…”

“…The SLC permits the selection of highly motile and viable spermatozoa, with good chromatin integrity and better resistance to cryopreservation (Martinez‐Alborcia et al, , ). Furthermore, SLC is currently the most‐promising method for fast (∼30 min) purification of viable spermatozoa through species‐specific colloids (i.e., Androcoll™‐P for porcine and Androcoll™‐E for equine) (Morrell, ; Morrell & Wallgren, ). Yet, full integration of SLC in the swine breeding industry remains limited, likely due to its cost.…”

“…Nanoparticles offer the opportunity to specifically target spermatozoa, and—like the use of colloid conjugated‐silica nanoparticles for centrifugation‐based sperm purification methods (Morrell, )—may become part of standard practices in commercial settings. Magnetic iron oxide nanoparticles (Fe 3 O 4 ), for example, offer specific properties that facilitate sperm purification: biocompatibility (soluble in water‐based solutions), physical nature (i.e., size and surface characteristics for bio‐conjugation), and magnetism (Pankhurst, Connolly, Jones, & Dobson, ).…”

Purification of cryopreserved camel spermatozoa following protease‐based semen liquefaction by lectin‐functionalized DNA‐defrag magnetic nanoparticles

“…The typical procedures for sperm purification rely basically either on sedimentation or migration approaches to isolate fertile spermatozoa based on their density or motility (Singh et al., 2019). These include different density gradient filtration strategies (Morrell, 2016), swim‐up assay (Arias et al., 2017), single layer centrifugation (Nongbua et al., 2017) and Sephadex column filtration (Galarza et al., 2018). Moreover, taking the biochemical properties of abnormal spermatozoa into account, that is, lack of plasma membrane integrity and abnormal surface glycocalyx, has played an influential rule in developing these procedures even further (Odhiambo et al., 2011).…”