Analysis of neovascularization of PEGT/PBT-copolymer dermis substitutes in balb/c-mice
ABSTRACT A fundamental prerequisite for using degradable synthetic biopolymers as composite skin substitutes is the ability to establish vascular tissue. PEGT/PBT block-copolymer matrices have previously been shown as a favorable dermal substitute. In this study, quantitative data on neovascularization of PEGT/PBT block-copolymer matrices are presented.
PEGT/PBT-block-copolymer discs of three different pore diameters (1: < 75 microm, 2: 75-212 microm, 3: 250-300 microm) were implanted into dorsal skinfold chambers of balb/c mice. Histological sections were evaluated 7, 14, and 21 days post implantation by light and scanning electron microscopy. Blood vessel analysis was performed by means of digital image analysis (n = 288) of hematoxylin/eosin stained sections within apical (AOF) and basal (BOF) observation fields of the matrices.
Twenty-one days after implantation the density of blood vessels within the BOF of the scaffolds with a pore size of 75-212 and 250-300 microm were 4.6 +/- 0.45 and 5.8 +/- 0.62 (mean +/- S.E.M.; blood vessel profiles (BVF)), respectively. In <75 microm scaffolds, smaller numbers of BVF were found (4.2 +/- 0.39). In contrast, the evaluation within the AOF revealed significantly higher numbers of BVF in 75-212 microm group (3.5 +/- 0.49) and 250-300 microm group (4.5 +/- 0.66) as compared to the < 75 microm group (2.3 +/- 0.48).
There is evidence that the three-dimensional structure of PEGT/PBT-block-copolymer (pore size structure) influences neovascularization. The porous structures of copolymer matrices with adequate interconnection of pores (pore sizes of 75-212 and 250-300 microm) are characterized by faster ingrowth of vascular tissue.
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ABSTRACT: PEGT/PBT (polyethylene glycol terephthalate/polybutylene terephthalate) copolymer matrices with three different surface coatings [calcium-phosphate (Ca-P), collagen, and gas plasma] were placed into dorsal skinfold chambers of 24 balb/c mice. Untreated PEGT/PBT matrices served as the controls. The basal surfaces of the implants directly contacted the striated skin muscle. Neovascularization of the implants was analyzed by intravital fluorescence microscopy. Microcirculatory observations were performed in the surrounding skin muscle, at the border zone of the implant, and in the center of the implant. The functional vessel density (FVD; mm/mm2), as the length of perfused microvessels per observation area, was measured by computer-assisted analysis. The FVD served as the parameter of neovascularization. At the end of the protocol, histological observation of hematoxylin/eosin-standard-stained sections was performed by light microscopy. The FVD in the center of the implant on day 8 was only observed in gas-plasma-coated (8.8 +/- 10.2 mm/mm2) and Ca-P-coated implants (0.8 +/- 2.0 mm/mm2). None of the other groups showed perfused microvessels in the center of the implant on day 8 (p < 0.05). The FVD values in the center of the gas-plasma-coated and the Ca-P-coated implants were 20.7 +/- 8.2 and 19.2 +/- 15.5 mm/mm2 as compared with 7.1 +/- 17.4 and 7.7 +/- 5.9 mm/mm2 for collagen-coated and untreated implants on day 16. The histological examination confirmed the profound microvascular ingrowth into the matrix pores of the gas-plasma-treated and the Ca-P-coated copolymer matrices in the center of the implants. The study showed that the ingrowth of microvessels into PEGT/PBT matrices can be accelerated by Ca-P coating and gas plasma treatment in the dorsal skinfold chamber in mice.European Surgical Research 03/2007; 39(2):75-81. DOI:10.1159/000099146 · 2.47 Impact Factor
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ABSTRACT: In view of their pain-relieving effect, the non steroidal anti-inflammatory drugs are more and more used as a pain-reducing component in modern wound dressings. To analyse the effect on new blood vessel growth, implants from Biatain Ibu, a polyurethane foam containing ibuprofen, were inserted into the dorsal skinfold chamber of BALB/c mice. Implants from ibuprofen-free polyurethane foam Biatain served as controls (n = 10 per group). Blood vessel growth and the functional vessel density (FVD) as a parameter for microvascularization of implant's border zone were assessed by intravital fluorescence microscopy (IVFM). IVFM was performed on days 3, 7 and 12 after implantation. Direct comparison showed no significant differences in FVD (mm/mm(2)) for the border zone of the ibuprofen-releasing implants versus controls on day 3 (185.49 +/- 4.75 versus 197.17 +/- 5.21) and day 7 (229.60 +/- 8.53 versus 247.99 +/- 5.39). However, the IVFM showed a significant increased FVD for ibuprofen-releasing implants (301.30 +/- 8.44 versus 279.24 +/- 5.78) on day 12 (P < 0.05). Also, a significant increase of FVD was detected for the ibuprofen-releasing implants throughout the implantation time of 12 days. This study shows that local release of small-dose ibuprofen from a polyurethane dressing does not decrease new blood vessel growth during the implantation time of 12 days. In the end, the microvascularization of implant's border zones in both groups was found comparatively undisturbed.International Wound Journal 07/2008; 5(3):464-9. DOI:10.1111/j.1742-481X.2007.00403.x · 2.15 Impact Factor
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ABSTRACT: A dermal equivalent applied in the treatment of scalds has been attracting much attention. We report here the fabrication of a bilayer dermal equivalent (BDE) composed of collagen-sulfonated carboxymethyl chitosan (SCC) porous scaffold and silicone membrane, and its application for accelerating the healing of skin scalds in a Bama miniature pig model. Firstly, the SCC was synthesized, and its chemical structure was characterized by FTIR and 1H- NMR.Then the effect of the ratio of the SCC on the microstructure of the collagen-SCC porous scaffolds was investigated. Sheet-like structure and bigger pores in the scaffolds appeared gradually along with the increase of the SCC amount. In vitro culture of human fibroblasts proved that the scaffold facilitated the proliferation of cells, confirming that it can function as a physical template with good cytocompatibility. Two kinds of BDEs ,i.e. collagen- chitosan/silicone membrane (BDE1) control and collagen-SCC/silicone membrane (BDE2) ,were used to repair skin scalds of Bama miniature pigs. The healing process of both BDEs was studied by macroscopic observation and H&E staining. Immunohistochemical staining of VEGF and CD34 were performed to investigate the angiogenesis ability of these two kinds of BDEs.The results showed that compared to the BDE1,the BDE2 had a stronger ability to enhance the angiogenesis of the skin equivalent and the regeneration of the dermal layer. Transplantation of split- thickness skin graft was further carried out on the regenerated dermal layers. Results showed that only the scalds treated by the BDE2 had the ability to support the restoration of full-thickness skin. All these results demonstrate that the BDE2 with the SCC and collagen as the major component has better effect on accelerating the healing of scalds than that of the BDEl with collagen and chitosan as the major component. One can also conclude that the sulfonated carboxymethyl chitosan, which is more structurally similar as heparin, should take the main role for the better repair results.Acta Polymerica Sinica 02/2009; 009(2):111-117. DOI:10.3724/SP.J.1105.2009.00111 · 0.64 Impact Factor