Poly(ether ester) block-copolymer scaffolds of different pore size were implanted into the dorsal skinfold chamber of balb/c mice. Using intravital fluorescent microscopy, the temporal course of neovascularization into these scaffolds was quantitatively analyzed. Three scaffold groups (diameter, 5 mm; 220 -260 thickness, m; n ϭ 30) were implanted. Different pore sizes were evaluated: small (20 -75 m), medium (75-212 m) and large pores (250 -300 m). Measurements were performed on days 8, 12, 16, and 20 in the surrounding normal tissue, in the border zone, and in the center of the scaffold. Standard microcirculatory parameters were assessed (plasma leakage, vessel diameter, red blood cell velocity, and functional vessel density). The largepored scaffolds showed significantly higher functional vessel density in the border zone and in the center (days 8 and 12) compared with the scaffold with the small and mediumsized pores. These data correlated with a larger vessel diameter and a higher red blood cell velocity in the largepored scaffold group. Interestingly, during the evaluation period the microcirculatory parameters on the edge of the scaffolds returned to values similar to those found in the surrounding tissue. In the center of the scaffold, however, neovascularization was still active 20 days after implantation. Plasma leakage and vessel diameter were higher in the center of the scaffold. Red blood cell velocity and functional vessel density were 50% lower than in the surrounding tissue. In conclusion, the dorsal skinfold chamber model in mice allows long-term study of blood vessel growth and remodeling in porous biomedical materials. The rate of vessel ingrowth into poly(ether ester) block-copolymer scaffolds is influenced by pore size and was highest in the scaffold with the largest pores. The data generated with this model contribute to knowledge about the development of functional vessels and tissue ingrowth into biomaterials.

Thoracic wall reconstruction provides sufficient thoracic wall stability to maintain pulmonary function, but postoperative pain and sensation disorders are considerable. However, chest wall repair can contribute to palliation and even cure after full-thickness resections.

The recovery of skin function is the goal of each burn surgeon. Split-skin graft treatment of full-thickness skin defects leads to scar formation, which is often vulnerable and instable. Therefore, the aim of this study was to analyze wound healing and scar tissue formation in acute full-thickness wounds treated with clinically available biopolymer dermal regeneration templates. Full-thickness wounds (3 x 3 cm) on both flanks of Gottingen mini pigs (n= 3) were treated with split-thickness skin graft alone or in combination with a 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) cross-linked-collagen scaffold, Integra, or a polyethyleneglycol terephthalate-polybutylene terephthalate (PEGT/PBT) scaffold. The wounds (n= 12 per group) were examined weekly for six weeks to evaluate graft take, contraction (planimetry), and cosmetic appearance. Histologic samples taken after one and six weeks were used to assess scaffold angiogenesis, biocompatibility, and scar tissue quality. In all wounds, one week postwounding graft take was between 93 and 100 percent. The control wound, treated with split-skin graft, showed little granulation tissue formation, whereas the EDC-collagen treated wounds showed two to three times more granulation tissue formation. The collagen scaffold was completely degraded within one week. The Integra and PEGT/PBT scaffolds showed angiogenesis only through two-thirds of the scaffold, which resulted in loss of integrity of the epidermis. Only basal cells survived, proliferated, and regenerated a fully differentiated epidermis within three weeks. Granulation thickness was comparable to collagen scaffold-treated wounds. After six weeks, control wounds showed a wound contraction of 27.2 +/- 6.1 percent, Integra-treated wounds 34.6 +/- 6.4 percent, collagen scaffold-treated wounds 38.1 +/- 5.0 percent, and PEGT/PBT scaffold-treated wounds 54.5 +/- 3.9 percent. The latter wounds had significantly more contraction than wounds of other treatment groups. Microscopically, the control and collagen scaffold-treated wounds showed an immature scar tissue that was two times thicker in the EDC-collagen treated wounds. The Integra-treated wounds showed nondegraded collagen scaffold fibers with partly de novo dermal tissue formation and partly areas with giant cells and other inflammatory cells. The PEGT/PBT scaffold was almost completely degraded. Scaffold particles were phagocytosized and degraded intracellularly by clusters of macrophages. The scar tissue was in the early phase of ECM remodeling. In conclusion, this study showed that the rate of dermal tissue formation and scarring is influenced by the rate of scaffold angiogenesis, degradation, and host response induced by the scaffold materials.