Sperm microencapsulation in bovine: An overview

Abstract

Artificial insemination is so far the most successful and widely adopted assisted reproductive technique for genetic improvement in bovines. Despite their widespread adoption, the field conception rate using frozen semen straws remain low. Prediction of ovulation time, the short lifespan of frozen-thawed sperm, and retrograde backflow of semen following insemination result in fewer sperm available in the sperm reservoir in the oviduct and thus lessen the chances of fertilization. To tackle this, the idea of sustained release of spermatozoa inside the oviduct to maximize the odds of fertilizing the descendent ova is generated. Cell microencapsulation is a strategy that allows the implantation of cells, keeping the cells isolated from the host immune response by semipermeable membrane permitting the selective diffusion of gases, nutrients, and therapeutics but not of host immune cells. At present, few studies have been conducted where spermatozoa were encapsulated in a polymer shell/bead and successfully cryopreserved. The frozen-thawed encapsulated spermatozoa had shown comparable results in terms of in vitro functional assessment as well as in achieving pregnancy as compared to conventional semen dose. The purity of encapsulating material is very crucial to nullify maternal immune response as well as to achieve higher biocompatibility. In this manuscript, an overview of sperm encapsulation has been compiled, with more stress on types of encapsulating materials, their characterization, purity, and prospects of this method to come up as a robust method for achieving higher success following artificial insemination.