Revascularization promoted by platelet pro-angiogenic factors or hyaluronan oligomers – A step towards endodontic regeneration using injectable systems

INTRODUCTION: Revascularization of pulp canal after endodontic treatment attains to rescue teeth from mid-term extraction fate, and can be promoted by the injection of hydrogels containing adequate cues. Herein are explored the proangiogenic effect of platelet-origin mediators modulated release [1] or hyaluronan oligomers instructive cues [2] within hydrogels aiming endodontic regeneration. METHODS: Hyaluronic acid (HA) hydrogels incorporating PL were produced by mixing 2% aldehyde-modified HA solution containing aldehyde-functionalized cellulose nanocrystals (CNCs) with 2% hydrazide- functionalized HA dissolved in human platelet lysate (PL). Were assessed the sprouting of human dental pulp cells (hDPCs) or DPCs/HUVECs 1:1 pellets encapsulated in the HA hydrogels, and the neovascularization in a chicken choriallantoic membrane (CAM) assay. Also, low (LMW) or high (HMW) molecular weight (6 kDa and 230 kDa; Lifecore) HA were immobilized over methacrylated gelatin hydrogels (GelMA) and the response of HUVECs in terms of viability and arrangement analyzed. RESULTS & DISCUSSION: PL incorporation enhanced the sprouting of DPCs both in single and co-cultures (p>0.001). Moreover, the combined effect of PL and DPCs encapsulation promoted the ingrowth of vascularized tissue into the hydrogels. The immobilization of LMW-HA over GelMA hydrogels enhanced the metabolic activity and promoted the organization of HUVECs into capilarlikestructures. CONCLUSIONS: Our findings from in vitro studies show that both the incorporation of humanoriginproangiogenic growth factors and the creation of instructive paths of HA oligomers within injectable hydrogels, might promote the revascularization required for endodontic regeneration.