title: Bladder tissue regeneration using acellular bi-layer silk scaffolds in a large animal model of augmentation cystoplasty.
abstract: Acellular scaffolds derived from Bombyx mori silk fibroin were investigated for their ability to support functional tissue regeneration in a porcine model of augmentation cystoplasty. Two bi-layer matrix configurations were fabricated by solvent-casting/salt leaching either alone (Group 1) or in combination with silk film casting (Group 2) to yield porous foams buttressed by heterogeneous surface pore occlusions or homogenous silk films, respectively. Bladder augmentation was performed with each scaffold group (6 × 6 cm(2)) in juvenile Yorkshire swine for 3 m of implantation. Augmented animals exhibited high rates of survival (Group 1: 5/6, 83%; Group 2: 4/4, 100%) and voluntary voiding over the course of the study period. Urodynamic evaluations demonstrated mean increases in bladder capacity over pre-operative levels (Group 1: 277%; Group 2: 153%) which exceeded nonsurgical control gains (144%) encountered due to animal growth.In addition, animals augmented with both matrix configurations displayed increases in bladder compliance over pre-operative levels(Group 1: 357%; Group 2: 338%) similar to growth-related elevations observed in non-surgical controls (354%) [corrected]. Gross tissue evaluations revealed that both matrix configurations supported extensive de novo tissue formation throughout the entire original implantation site which exhibited ultimate tensile strength similar to nonsurgical counterparts. Histological and immunohistochemical analyses showed that both implant groups promoted comparable extents of smooth muscle regeneration and contractile protein (α-smooth muscle actin and SM22α) expression within defect sites similar to controls. Parallel evaluations demonstrated the formation of a transitional, multi-layered urothelium with prominent cytokeratin, uroplakin, and p63 protein expression in both matrix groups. De novo innervation and vascularization processes were evident in all regenerated tissues indicated by synaptophysin-positive neuronal cells and vessels lined with CD31 expressing endothelial cells. Ex vivo organ bath studies demonstrated that regenerated tissues supported by both silk matrices displayed contractile responses to carbachol, α,β-methylene-ATP, KCl, and electrical field stimulation similar to controls. Our data detail the ability of acellular silk scaffolds to support regeneration of innervated, vascularized smooth muscle and urothelial tissues within 3 m with structural, mechanical, and functional properties comparable to native tissue in a porcine model of bladder repair.
authors: Urological Diseases Research Center, Boston Children's Hospital, Boston, MA 02115, USA.
authors: Duong D
authors: DD
authors: Tu
authors: Yeun Goo
authors: YG
authors: Chung
authors: Eun Seok
authors: ES
authors: Gil
authors: Abhishek
authors: A
authors: Seth
authors: Debra
authors: D
authors: Franck
authors: Vivian
authors: V
authors: Cristofaro
authors: Maryrose P
authors: MP
authors: Sullivan
authors: Dolores
authors: D
authors: Di Vizio
authors: Pablo
authors: P
authors: Gomez
authors: Rosalyn M
authors: RM
authors: Adam
authors: David L
authors: DL
authors: Kaplan
authors: Carlos R
authors: CR
authors: Estrada
authors: Joshua R
authors: JR
authors: Mauney
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry; D012831:Bombyx; D004195:Disease Models, Animal; D005260:Female; D005349:Fibroins / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D009119:Muscle Contraction / Q000502:physiology; D009130:Muscle, Smooth / Q000166:cytology / Q000378:metabolism; D012038:Regeneration / Q000502:physiology*; D013552:Swine; D023822:Tissue Engineering / Q000379:methods*; D054457:Tissue Scaffolds; D001743:Urinary Bladder / Q000166:cytology / Q000378:metabolism*; D014563:Urodynamics / Q000502:physiology; D013520:Urologic Surgical Procedures; D019459:Urothelium / Q000166:cytology / Q000378:metabolism
chemical_list: D001672:Biocompatible Materials; D005349:Fibroins
keywords: Bladder; Silk; Tissue engineering; Wound healing
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