C-32: Lyoprotection during bovine sperm desiccation and osmotic damage model

Abstract

Designing excipients for stable desiccation preservation protocols of bovine sperm at low moisture content and ambient storage conditions for the animal husbandry industry requires subsequent retention of motility. We shall discuss the role of various excipients such as the lyoprotectant trehalose and osmotolerant sorbitol plays in bovine sperm. Since it is hypothesized that much of the damage during drying is related to the osmotic stress encountered due to increased osmolarity of the extracellular environment, we wanted to develop a predictive tool that captured the osmotic damage of sperm during drying. Our approach was to subject bovine sperm to anisosmotic environments for different times and then extract parameters for motility loss and subsequently predict desiccation experiments. We saw a two-step motility response; a rapid drop that can be considered instantaneous and a slower one. We developed two models (a) First order rate injury model (Fast or Slow) and (b) Multi-modal (MM) injury model. For desiccation, the MM model was able to closely bracket motility loss as an osmotic change event with a time independent and a time dependent component. While the mechanistic basis of osmotic damage requires further exploration, the model can serve as a bracketing tool for predicting motility loss during desiccation based on excipients designed to minimize osmotic damage.