Analysis of neovascularization of PEGT/PBT-copolymer dermis substitutes in balb/c-mice

Introduction 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. Materials and methods PEGT/PBT-block-copolymer discs of three different pore diameters (1: <75 μm, 2: 75–212 μm, 3: 250–300 μm) 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. Results 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 μm were 4.6 ± 0.45 and 5.8 ± 0.62 (mean ± S.E.M.; blood vessel profiles (BVF)), respectively. In <75 μm 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 μm group (3.5 ± 0.49) and 250–300 μm group (4.5 ± 0.66) as compared to the <75 μm group (2.3 ± 0.48). Conclusion 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 μm) are characterized by faster ingrowth of vascular tissue