Introduction: Engineered constructs that attempt to restore or regenerate tissue to fill large defects due to injury or tumor resection often fail due to poor or absent vascularization. Research suggests that during in vivo angiogenesis in the mesentery, capillary sprout endothelial cells and pericytes preferentially migrate along elastic fibers of the extracellular matrix (ECM) in order to form neo-vessels1. It is our goal to engineer nano-structured, three-dimensional scaffolds composed of natural polymeric fibrils that mimic the composition, structure, and nano-mechanics of natural ECM and guide microvessel assembly.
Methods: We have previously shown that scaffolds composed of a blend of the natural polymers silk fibroin (SF) and chitosan (CS) regenerate a well vascularized and integrated abdominal wall in a guinea pig ventral hernia repair model 2,3. In the current study, we induced the formation and alignment of SF fibrils embedded within a CS matrix using the dielectrophoresis technique4. Dielectrophoresis was applied to a 75:25 blend of SFCS solution via an interdigitated bar electrode at 10 Vpp and 100 kHz for 1 hour while freezing the sample with liquid nitrogen vapor. The sample was lyophilized to generate the engineered scaffold structure. The structure of the resultant SFCS scaffold was characterized using polarized light and atomic force microscopies.
Results: We produced a nano-structured layered sheet configuration in three-dimensions similar to the basement membrane. The layered sheets of SFCS were embedded with aligned fibrils of SF (diameter: 1.8±0.2, height: 32.9±3.9 nm) (Figure 1).
Conclusions: The unique composition and the engineered structure of these scaffolds make them ideal for guided in vivo blood vessel assembly as studied in the in vivo rat mesentery model.
1: Anderson CR, Ponce AM, Price RJ.. Journal of Histochemistry and Cytochemistry. 2004. 52 (8): 1063-1072. 2: Gobin AS, Froude VE, Mathur AB. J Biomed Mater Res A. 2005. 74(3): 465-73. 3: Gobin AS, Butler CE, Mathur AB. J Biomed Mater Res A. August 2005, in press. 4: Gascoyne PR, Vykoukal J. Electrophoresis 2002;23(13):1973-1983