title: Electrospun bilayer fibrous scaffolds for enhanced cell infiltration and vascularization in vivo.
abstract: Bilayer poly(L-lactic acid) fibrous scaffolds consisting of a thin aligned-fiber layer (AFL) and a relatively thick random-fiber layer (RFL) were fabricated by an electrospinning technique, which uses two slowly rotating parallel disks as the collector. The morphology and structure of the bilayer scaffolds were examined by high-magnification scanning electron microscopy and confocal microscopy. The bilayer scaffolds demonstrated a gradual variation in through-thickness porosity and fiber alignment and an average porosity much higher than that of conventionally electrospun scaffolds (controls) with randomly distributed fibers. The biocompatibility and biological performance of the bilayer fibrous scaffolds were evaluated by in vivo experiments involving subcutaneous scaffold implantation in Sprague-Dawley rats, followed by histology and immunohistochemistry studies. The results illustrate the potential of the bilayer scaffolds to overcome major limitations of conventionally electrospun scaffolds associated with intrinsically small pores, low porosity and, consequently, poor cell infiltration. The significantly higher porosity and larger pore size of RFL enhances cell motility through the scaffold thickness, whereas the relatively dense structure of AFL provides the scaffold with the necessary mechanical strength. The bilayer scaffolds show more than two times higher cell infiltration than controls during implantation in vivo. The unique structure of the bilayer scaffolds promotes collagen fiber deposition, cell proliferation, and ingrowth of smooth muscle cells and endothelial cells in vivo. The results of this study illustrate the high prospect of the fabricated bilayer fibrous scaffolds in tissue engineering and regeneration.
authors.affiliation: Department of Mechanical Engineering, University of California, Berkeley, CA 94720, USA.
authors.forename: Juan
authors.initials: J
authors.lastname: Pu
authors.affiliation: Department of Bioengineering, University of California, Berkeley, CA 94720, USA.
authors.forename: Falei
authors.initials: F
authors.lastname: Yuan
authors.affiliation: Department of Bioengineering, University of California, Berkeley, CA 94720, USA.
authors.forename: Song
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Mechanical Engineering, University of California, Berkeley, CA 94720, USA. Electronic address: kyriakos@me.berkeley.edu.
authors.forename: Kyriakos
authors.initials: K
authors.lastname: Komvopoulos
mesh_terms: D000818:Animals; D002465:Cell Movement; D049109:Cell Proliferation; D003094:Collagen / Q000096:biosynthesis; D042783:Endothelial Cells / Q000378:metabolism*; D020007:Implants, Experimental; D019344:Lactic Acid / Q000737:chemistry*; D032389:Myocytes, Smooth Muscle / Q000378:metabolism*; D011091:Polyesters; D011108:Polymers / Q000737:chemistry*; D016062:Porosity; D051381:Rats; D017207:Rats, Sprague-Dawley; D054457:Tissue Scaffolds / Q000737:chemistry*
chemical_list: D011091:Polyesters; D011108:Polymers; D019344:Lactic Acid; C033616:poly(lactide); D003094:Collagen
keywords: Bilayer fibrous scaffolds; Cell infiltration; Electrospinning; Mechanical strength; Tissue engineering