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. 2022 Dec 23;24:197–235. doi: 10.1016/j.bioactmat.2022.11.019

Fig. 4.

Fig. 4

3D printing for wound healing application. (A) Poly (lactic-co-glycolic acid) (PLGA)/Alginate hydrogels (i) Schematic process of bilayer PLGA/Alginate membrane scaffold. (ii) In vivo wound healing of blank control, PLGA, alginate hydrogel (AH), and bilayer membrane scaffold (BLM) scaffold on days 0, 4, 8, and 12. (iii) Analysis of wound healing rates for different treatments. (iv) Quantification of collagen with trichrome blue staining. (v) Quantification of blood vessel area by analyzing the CD31-positive area. Reprinted and adapted with permission from Yang et al., 2019 [78]. (B). Polyacrylamide (PAM) based hydrogels (i) Swollen state of solid and 3D printed super porous polyacrylamide PAM/hydroxypropyl methylcellulose (HPMC) hydrogels and their schematic representation. (ii) Healing process of wounds treated by PAM/chitosan, (silver nanoparticle) AgNP-PAM/HPMC, or PAM/HPMC over time. (iii) Closure degree of wounds over time. Quantification of scar width (iv) and newborn granulation tissue (v) by H&E staining, and quantification of blood vessels (vi) and thickness of neo-epidermis (vii) by Mason's trichrome staining. Reprinted and adapted with permission from Wu et al., 2019 [79]. (C) Gelatin methacryloyl (GelMA)-vascular endothelial growth factor (VEGF) printing (i) Schematic illustration of in vivo printing of GelMA-VEGF hydrogel by a handheld bioprinter. The in situ crosslinking process promotes the proper adhesion of the hydrogel to the wound surface. (ii) Representative pictures of the wounds administrated with VEGF, GelMA or GelMA + VEGF on day 7 and day 14 post surgery. (iii) Wound contraction relative to the original wound size. (iv) wound re-epithelialization, calculated based on the area of new epithelium over the total wound area. (v) Amount of granulation tissue. (vi) scar elevation index (SEI) is calculated based on the total area of the healed skin over the area of normal skin below the buildup of hypertrophic scarring. (vii) The degree of inflammation was analyzed by the hematoxylin and eosin (H&E) staining of wound sections to observe the infiltration of inflammatory cells. Reprinted and adapted with permission from Nuutila et al., 2022 [81].