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To investigate the effects of three kinds of artificial dermal scaffolds on vascularization and scar formation of wounds in pigs with full-thickness burn.Eighteen Bama miniature pigs were divided into chitosan scaffold (CS) group, sulfonated carboxymethyl chitosan scaffold (SCCS) group, and acellular dermal matrix (ADM) scaffold group according to the random number table, with 6 pigs in each group. Every pig in all groups was inflicted with 4 or 8 full-thickness scald wounds on the back (totally 96 wounds). Forty-eight hours after injury, eschars of all wounds were excised. Twenty-four wounds in CS group were transplanted with double-layer artificial dermis of collagen-chitosan and silicone rubber, those in SCCS group with double-layer artificial dermis of collagen-sulfonated carboxymethyl chitosan and silicone rubber, and those in ADM scaffold group with ADM. The rest 24 wounds in the three groups were dressed with vaseline gauze as control group. After 2 weeks of treatment, all wounds of every group were covered with skin. In post treatment (scaffold transplantation or gauze covering) week (PTW) 1, 2, 3, and 4, gross condition of wound was observed, and specimens from central parts of wounds were harvested for observation and assessment of vessels or cells with positive expression of CD31, α smooth muscle actin (α-SMA), TGF-β(1) and TGF-β(3) with SP staining. Data were processed with one-way analysis of variance and LSD test.(1) Degree of vascularization in SCCS group was better than that in the other three groups. (2) The number of vessels with positive expression of CD31 in CS, SCCS, ADM scaffold, and control groups increased gradually from PTW 1 to PTW 3, and decreased in PTW 4. There were statistical differences among 4 groups from PTW 1 to PTW 4 (with F value respectively 24.005, 38.822, 25.274, 3.856, P0.05 or P0.01). The numbers of vessels that expressed CD31 in SCCS group from PTW 1 to PTW 3 were more than those in the other three groups (with P values all below 0.05). (3) The numbers of vessels that expressed α-SMA in CS, SCCS, and ADM scaffold groups from PTW 1 to PTW 3 showed the similar trend of change to those of vessels that expressed CD31, which increased gradually in control group from PTW 1 to PTW 4. There were obvious differences among 4 groups from PTW 1 to PTW 4 (with F value respectively 22.637, 28.087, 62.651, 18.055, P values all below 0.01). The number of vessels that expressed α-SMA in SCCS group from PTW 1 to PTW 4 was more than that in the other three groups (with P values all below 0.05). (4) From PTW 1 to PTW 4, the number of cells with expression of TGF-β(1) in CS group was respectively (127 ± 8), (167 ± 19), (170 ± 18), (144 ± 10) per 400 times visual field, that in SCCS group was respectively (171 ± 17), (207 ± 25), (130 ± 30), (69 ± 16) per 400 times visual field, that in ADM scaffold group was respectively (106 ± 8), (159 ± 17), (171 ± 11), (145 ± 11) per 400 times visual field, and that in control group was respectively (100 ± 20), (150 ± 18), (200 ± 14), (172 ± 20) per 400 times visual field. There were statistical differences among 4 groups from PTW 1 to PTW 4 (with F value respectively 29.675, 9.503, 13.107, 54.515, P values all below 0.01). Compared with those in SCCS group, the number of cells that expressed TGF-β(1) in the other three groups was decreased in PTW 1, 2 but increased in PTW 3, 4 (with P values all below 0.05). (5) The number of cells that expressed TGF-β(3) in 4 groups increased gradually from PTW 1 to PTW 3, and decreased or increased continually in PTW 4. There were statistical differences among 4 groups from PTW 1 to PTW 4 (with F value respectively 140.612, 945.850, 714.037, 119.147, P values all below 0.01). The number of cells with positive expression of TGF-β(3) in SCCS group from PTW 1 to PTW 4 was more than that in the other three groups (with P values all below 0.05).The collagen-sulfonated carboxymethyl chitosan dermal scaffold can rapidly induce growth and maturation of blood vessels during wound healing after burn. It is beneficial for wound repair at early stage with inhibition of scar proliferation.

To investigate the effects of vascular endothelial growth factor (VEGF) DNA plasmids, encoded in collagen-sulfonated carboxymethyl chitosan porous scaffold, on the angiogenesis in full-thickness burn wounds.Wounds and pathological changes were observed at Week 1, 2, 3 and 4 after pure collagen-sulfonated carboxymethyl chitosan porous scaffold (group A) and collagen-sulfonated carboxymethyl chitosan porous scaffold encoding VEGF DNA plasmids (group B) were transplanted onto eachar-removed wounds of full-thickness burn in 6 Bama miniature pigs respectively. Wound healing was observed by pathologic slides after epidermal grafting for 2 weeks (at Week 4) onto the surface of different dermal scaffolds transplanted on wounds for 2 weeks. At the same time, new-forming vessels expressing CD31 and mature vessels expressing α-SMA (α-smooth muscle actin) and the expression of VEGF in wounds at Week 1, 2, 3 and 4 were detected in situ by immunohistochemical staining. The burn wounds without any transplanted scaffold (group C) were studied as the controls.Wounds with various scaffolds were different from those without any scaffold. Angiogenesis of the group B was better than that of the group A. Neo-forming micro-vessels expressing CD31 in the wounds of group A or B at Week 1, 2, 3 and 4 were as follows: 18.7 ± 3.1, 25.7 ± 2.3, 36.8 ± 2.526.2 ± 2.9; 24.5 ± 3.8, 32.3 ± 2.8, 39.2 ± 2.227.3 ± 3.0. Mature vessels expressing α-SMA: 11.7 ± 1.9, 20.5 ± 1.9, 35.0 ± 4.524.0 ± 2.8; 20.2 ± 3.1, 33.5 ± 3.7, 38.2 ± 4.526.5 ± 2.3. The expressions of VEGF: 48.7 ± 7.9, 141.7 ± 9.1, 201.5 ± 8.6107.0 ± 8.2; 97.3 ± 7.9, 172.3 ± 8.1, 208.7 ± 8.3114.0 ± 5.8. Expressing intensity of CD31, α-SMA and VEGF in the wounds of group C at Week 1, 2, 34: 6.0 ± 2.0, 9.8 ± 3.4, 19.3 ± 2.518.7 ± 2.2; 3.7 ± 2.0, 8.7 ± 1.8, 13.0 ± 2.514.0 ± 2.8; 3.5 ± 2.3, 10.3 ± 3.5, 23.0 ± 5.621.5 ± 5.1. There were significant statistical differences among three groups.Artificial dermal scaffold encoding exogenous pDNA-VEGF can promote a quicker angiogenesis through a high expression of VEGF. Thus a full-thickness burn wound may be better repaired.

To compare differences of angiogenesis among collagen- chitosan, collagen-sulfonated carboxymethyl chitosan porous scaffolds and acellular dermal matrix after these three different scaffolds with silicone membrane were transplanted on the wounds of full thickness burn, and the wound repair of different scaffolds with epidermis grafting on.Angiogenesis in different dermal scaffolds, the wound surface and epidermis survival were observed in 1, 2, and 3 weeks after the three different scaffolds were respectively transplanted on wounds of full thickness burn with debridement in 6 Bama miniature pigs (total 18 pigs in 3 groups). At the same time, CD34 positive signals (neo-forming microvessels) were detected by immunohistochemical staining. The wounds without any scaffold transplantation were studied as the control.Angiogenesis had been fundamentally finished in 2 weeks after implantation of collagen- sulfonated carboxymethyl chitosan porous scaffold. And fundamental angiogenesis in collagen- chitosan porous scaffolds and acellular dermal matrix needed at least 3 weeks. Neo-forming micro-vessels perpendicular to wound beds with these three different scaffolds were more than those in the control wounds without scaffold. CD34 positive signals (neo-forming micro-vessels) were significantly higher in wounds at the second week than those in wounds at the first week. And those in wounds at the third week were significantly higher than those in wounds at the second week in all wounds with different scaffold transplantations and the control wounds. CD34 positive signals in the group of sulfonated carboxymethyl chitosan porous scaffold on the 1st, 2nd and 3rd week after the scaffold transplantation were significantly higher than those corresponding signals in the other three groups. Epidermis on the sulfonated carboxymethyl chitosan porous scaffold which had been transplanted on burn wound for 1 week could survive perfectly, however, epidermis on the collagen- chitosan porous scaffold or acellular dermal matrix could not survive until these two scaffolds had been transplanted on the burn wounds for at least 2 weeks.These three different scaffolds could repair the full thickness skin defects caused by burn, and angiogenesis of sulfonated carboxymethyl chitosan porous scaffold is the best.

To investigate the roles and differences of angiogenesis of different dermal scaffolds on wound contraction and apoptosis during full-thickness burn wound repair.Wounds were observed at different time after the collagen-sulfonated carboxymethyl chitosan porous scaffold or collagen-chitosan porous scaffold or acellular dermal matrix were respectively transplanted on wounds of full thickness burn with debridement in Bama miniature pigs. At the same time, vessels and myo-fibroblasts expressing α-smooth muscle action(α-SMA) and apoptosis in wounds of different time were detected in situ by immunohistochemical staining, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling. The burn wounds without any scaffold transplantation were studied as the control.Wounds with different scaffolds transplantation were different from granulation wounds. Vessels expressing α-SMA had been increasing continuously in the wounds from 1 to 3 weeks after different scaffolds transplantation and decreased in wounds after epidermis had been grafted for 2 weeks on surface of the scaffolds transplanted on wounds for 2 weeks. Vessels expressing α-SMA were the most in the wounds with collagen-sulfonated carboxymethyl chitosan porous scaffold transplantation and the least in the control wounds without dermal scaffold at different time. Myo-fibroblasts expressing α-SMA was the least in the wounds with collagen-sulfonated carboxymethyl chitosan porous scaffold transplantation and the peak of expressions was on the 2nd week, however, the peak in the wounds with the other two scaffolds transplantation and in the control wound without dermal scaffold was on the 3rd week. Myo-fibroblasts expressing α-SMA was the most in the control wounds. Apoptosis had been increasing continuously in the transplantation wounds from 2 to 4 weeks after different scaffolds transplantation, however, apoptosis had begun to increase continuously from 3 to 4 weeks in the control wounds. Apoptosis was the most in the wounds with collagen-sulfonated carboxymethyl chitosan porous scaffold transplantation and the least in the control wounds without dermal scaffold from 3 to 4 weeks.Sulfonated carboxymethyl chitosan can promote migration of reparative cells and angiogenesis, and it can repair full-thickness burn wound fast and well.

Angiogenesis of dermal equivalent is one of the key issues for treatment of full thickness skin defects. To develop a gene-activated bilayer dermal equivalent (BDE), N,N,N-trimethyl chitosan chloride (TMC), a cationic gene delivery vector, was used to form complexes with the plasmid DNA encoding vascular endothelial growth factor-165 (VEGF-165), which was then incorporated into a collagen-chitosan/silicone membrane scaffold. To evaluate the angiogenesis property in vivo, full thickness skin defects were made on the back of pigs, into which the TMC/pDNA-VEGF complexes loaded BDE and other three control BDEs, i.e. the blank BDE, and the BDEs loaded with pDNA-VEGF and TMC/pDNA-eGFP complexes, respectively, were transplanted. Biopsy specimens were harvested at day 7, 10 and 14 after surgery for histology, immunohistochemistry, immunofluorescence, real-time quantitative PCR (RT-qPCR) and western blotting analyses. The results showed that the TMC/pDNA-VEGF group had the strongest VEGF expression in mRNA and protein levels, resulting in the highest densities of newly-formed and mature vessels. The ultra-thin skin graft was further transplanted onto the dermis regenerated by the TMC/pDNA-VEGF complexes loaded BDE at day 10 and well survived. At 112 days grafting, the healing skin had a similar structure and approximately 80% tensile strength of the normal skin.

To investigate angiogenesis of collagen-chitosan porous scaffold, and to study survive of skin grafts on the scaffold after bilayer dermal equivalent (BDE) was transplanted on wounds with full thickness skin defects.The full thickness skin defects were made on 10 Bama miniature pigs and the BDE composed of collagen-chitosan porous scaffold and silicone membrane was transplanted on wound. Angiogenesis in dermal equivalent, wound healing, and healing and survive of skin grafts on dermal equivalent were observed in 1, 2, and 3 weeks after the BDE transplantation. At the same time, CD34 positive signals (neo-forming micro-vessels) were detected by immunohistochemical staining.Inflammatory cells and fibroblasts infiltrated into dermal equivalent and a few new micro-vessels had been formed in 1 week after the BDE transplantation; neo-forming micro-vessels perpendicular to wound bed had increased significantly in 2 weeks after the BDE transplantation; neo-forming micro-vessels could be observed in almost all dermal equivalents in 3 weeks after the BDE transplantation. CD34 positive signals (neo-forming micro-vessels) in 3 weeks after the BDE transplantation was much more than those in 2 weeks after the BDE transplantation, and CD34 positive signals in 2 weeks after the BDE transplantation was much more than those in 1 week after the BDE transplantation. Survival rate of intermediate split thickness skin graft were 10%, 70% and 100% respectively after the skin grafts had been grafted for 2 weeks on surface of the scaffold which had been transplanted for 1, 2 and 3 weeks. Epidermis which had been grafted on surface of the scaffold for 1 or 2 weeks could perfectly survive after BDE had been transplanted for 1 or 2 weeks.Collagen-chitosan porous scaffold plays a very important role in wound healing of full thickness skin defect and can induce fibroblast infiltration and new micro-vessel formation. Epidermis grafted on surface of collagen-chitosan porous scaffold can perfectly repair wounds, and it has brilliant applied prospects in repairing skin defect.

To observe the effect of the early transplantation of double rectus abdominis musculo-cutaneous flaps on the repair of electrical injury of the wrist.The study involved six patients suffering from circumferential deep electrical burn with only small amount of normal skin left on the dorsal side. The wounds were covered with double rectus abdominis musculo-cutaneous flaps raised from the upper abdomen with pedicles in both proximal and distal ends at an early postburn stage. The postoperative recovery of wrist function and wound repair were evaluated.The wrist wounds in all the 6 patients were primarily healed, with perfect function and appearance.Early application of double rectus abdominis musculocutaneous flaps on the electrically injured wrists can promote the wound healing processes and plays important roles in the preservation of wrist function.