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: 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. · 1.60 Impact Factor
- Acta Polymerica Sinica - ACTA POLYM SIN. 01/2009; 009(2):111-117.
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ABSTRACT: The NO/cGMP pathway plays a crucial role in regulation of tissue perfusion. However, a NO-induced desensitization of cGMP-mediated relaxation has been reported in isolated tissue. To examine whether a similar phenomenon can be detected in vivo, we analyzed relaxations of microvessels in response to repeated applications of NO. The investigations were performed by means of dynamic intravital fluorescence microscopy in the dorsal skinfold chamber of female balb/mice. First, the microvasculature was maximally preconstricted by the application of the vasoconstrictor 5-hydroxytryptamine. Subsequently, relaxation was induced by applying an NO-donator, the S-nitrosoglutathione, to the contracted vessels. Following buffer exchange, constriction and relaxation were repeated. Drugs were given topically into the chamber, directly onto the skin muscle. The response of arterioles to topical administration of vasoactive drugs was determined as the change of the diameter, and quantified using standard software. The relaxation of arterioles was reduced after repetitive application. The short pretreatment with NO-donor entailed a reduced relaxation of arterioles in response to following application. The absolute change in vessel diameter induced by S-nitrosoglutathione was significantly reduced from 21 μm to 16 μm after the first and the second application, respectively. However, the data also revealed a noticeable reduction of the constricting activity of 5-hydroxytryptamine during the second application, indicating a possible desensitization of the 5-hydroxytryptamine response or a humoral and/or neuronal compensatory mechanisms. The NO-induced cGMP-mediated relaxation of microvessels was quantified, and the phenomenon of desensitization visualized in vivo by means of dynamic fluorescence microscopy.Journal of Surgical Research 11/2010; 164(1):169-74. · 2.02 Impact Factor