Chemical modification of hyaluronic acid improves its supportive action on embryo implantation

Hyaluronic acid (HA) is a supplement of the embryo transfer medium that improves embryo implantation. We have suggested that the supportive action of HA can be promoted by introducing additional artificial binding sites on the HA structure. HA was modified at carboxyl sites separately with thiol (SH) and N-hydroxysuccinimide (NHS), as mucoadhesive and amine-reactive groups, respectively. The mouse blastocysts were incubated with HA derivatives for 15 min. The HA coatings maintained their potential for enzymatic degradation and showed no detrimental effect on embryonic viability and developmental potential. After in vivo transfer, a significantly higher implantation rate was attained by HA-NHS treatment (80 %) compared with the HA-SH (53 %) and the commercial transfer medium, EmbryoGlue® (56 %). The HA-NHS was produced by a slight modification on the native structure of HA using a simple, fast, non-expensive and scalable chemistry which all promise applicability of this new HA derivative in assisted reproductive technologies.