The Intrinsic Relation between the Hydrogel Structure and In Vivo Performance of Hyaluronic Acid Dermal Fillers: A Comparative Study of Four Typical Dermal Fillers.

[BACKGROUND] Hyaluronic acid dermal fillers are composed of cross-linked viscoelastic particles with high biocompatibility. The performance of the fillers is determined by the viscoelastic properties of particles and the connecting force between particles. However, the relationships among the properties of fillers, the interaction of the gels and the surrounding tissue are not clear enough.

[METHOD] Four kinds of typical dermal filler were selected in this research to reveal the interaction between the gels and cells. A series of analytical tools was applied to characterize the structure and physicochemical properties of the gel, as well as observing their interaction with the surrounding tissues in vivo and discussing their internal mechanism.

[RESULT] The large particles internal the gel and the high rheological properties endow the Restylane2 with excellent support. However, these large-size particles have a significant impact on the metabolism of the local tissue surrounding the gel. Juvéderm3 present gel integrity with the high cohesiveness and superior support. The rational matching of large and small particles provides the Juvéderm3 with supporting capacity and excellent biological performance. Ifresh is characterized by small-size particles, moderate cohesiveness, good integrity, lower viscoelasticity and the superior cellular activity located the surrounding tissues. Cryohyaluron has high cohesion and medium particle size and it is prominent in cell behaviors involving localized tissues. Specific macroporous structure in the gel may facilitate the nutrients delivering and removing the waste.

[CONCLUSION] It's necessary to make the filler both sufficient support and biocompatibility through the rational matching of particle sizes and rheological properties. Gels with macroporous structured particle showed an advantage in this area by providing a space inside the particle.