TNFRSF11A and periodontitis: An example is the use of chitosan hydrogels for delivering NF-κB receptor activator (RANK) siRNA in a periodontitis mouse model, where in vivo studies demonstrated that fluorescent signals from the siRNA encapsulated in chitosan hydrogels can be sustained for up to 7 days—significantly longer than the less than one-day longevity of free RANK siRNA (Fig. 10a).583 This chitosan hydrogel could serve as a suitable reservoir and carrier for locally sustained delivery of siRNA in chronic inflammation therapy.