Application of coumaric acid and rhCOMP-Ang1 for the regeneration of hPLFs cells and critical-sized defects in rats (A) (Reprinted/adapted with permission from Ref. [63]. 2022, Elsevier). Application of PPCN-Sr revealed high levels of osteocalcin expression and cell infiltration in DAPI analysis in comparison to pure PPCN (a,b) Alizarin red stain test showed high mineralization in the PPCN-Sr group compared to the PPCN group(c,d) (B) (Reprinted/adapted with permission from Ref. [65]. 2018, Wiley Materials). Application of the chitin/poly(L-lactide-co-glycolide) (PLGA)-CaSO4 hydrogel with lactoferrin and substance P in calvarial bone regeneration in a critical-sized defect model in mice which was demonstrated with μ-CT images (a), quantification of B/TV% (b) (*: p < 0.05, **: p < 0.01, ns: not significant), H&E staining (c) and MTC staining (d) (black arrows indicate the mineralized and osteoid tissue) (C) (Reprinted/adapted with permission from Ref. [66]. 2021, Elsevier).