The Beneficial Effect of Carboxylated Poly-l-lysine On Cryosurvival of Vitrified Early Stage Embryos

BACKGROUND: In the vitrification of embryos, dimethyl sulfoxide (DMSO) is one of the most effective cryoprotectant agents (CPAs), but cytotoxic effects of DMSO on embryos are well known. Carboxylated poly-L-lysine (CPLL) has been identified as an effective cryoprotectant of cultured cell lines and mammalian oocytes. OBJECTIVE: To evaluate the efficacy and safety of CPLL as a CPA for developmental stage embryos. MATERIALS AND METHODS: Mouse 8-cell embryos and blastocysts were vitrified with ethylene glycol (EG), DMSO/EG, or CPLL/EG and the developmental potency assessed in vitro. RESULTS: In 8-cell embryos, there were no differences between the levels of survival and developmental progress into the blastocyst stage in each solution. At the blastocyst stage, the proportion of dead cells was significantly higher in the EG compared with other solutions. In contrast, there were no differences between the DMSO/EG and CPLL/EG. CONCLUSION: These results indicate that CPLL can be used as a replacement for DMSO in the vitrification of mouse embryos.