Asiaticoside-Loaded Nanosponges Hydrogel Has an Anti-inflammatory Effect and Promotes Human Dental Pulp Regeneration

Asiaticoside (AS) demonstrated potential in wound healing and anti-inflammation. However, its therapeutic applications are limited due to poor solubility and low bioavailability, which make it difficult to use as dental pulp capping agent. The nanosponges (Ns) are nanosized carriers capable of carrying small drug molecules. We proposed a method to encapsulate AS in Ns (asiaticoside-loaded nanosponges) and incorporate it into hydrogel (asiaticoside-loaded nanosponges hydrogel [AS/Ns-gel]).

Using different concentrations of polymer and carbopol four different fractions of asiaticoside-loaded nanosponges (N1-N4) and AS/Ns-gel (G1-G4) were prepared. The optimal fraction was determined by characterizing physiochemical properties and in vitro release kinetics. An in vitro model of inflammatory human dental pulp cells (hDPCs) was induced using a cytokine cocktail and/or lipopolysaccharide prior to application of AS/Ns-gel. Messenger ribonucleic acid (mRNA) and protein expression of inflammatory cytokines were measured. To assess the wound healing potential of AS/Ns-gel, an in vitro scratch test was performed.

N1/G3 AS/Ns-gel exhibited the most optimized and uniform particle size distribution, with good solubility, sustained AS release, and effective encapsulation. In an in vitro study of hDPCs pretreated with lipopolysaccharide or cytokine cocktail, the AS/Ns-gel downregulated interleukin 6 and interleukin 8 mRNA expression while upregulating interleukin 10 expression. Reverse transcription quantitative polymerase chain reaction and western blot analysis revealed a time-dependent increase in transforming growth factor β1, collagen type 1 and matrix metalloproteinase 9 mRNA/protein levels. Additionally, AS/Ns-gel accelerated hDPCs migration.

We successfully developed an AS/Ns-gel that reduced the expression of inflammatory cytokines in an inflamed pulp model in vitro. AS-loaded hydrogels have sustained release properties, promote cell proliferation and cell migration, thus suggesting its potential to be used in regenerative endodontic therapy.