INTRODUCTION: Permanent hernia repair materials rely on pro-fibrotic wound healing. As a result, repair sites are commonly composed of disorganized fibrotic tissue, resulting in greater risk of re-herniation. Electrospun scaffolds are a novel class of biomaterials which may provide a unique platform for the design of increasingly advanced soft tissue repair materials. These scaffolds are simple, inexpensive, non-woven materials composed of micro- or nano-scale polymer fibers which readily mimic structural elements of the natural extracellular matrix. Unlike currently available permanent meshes, absorbable electrospun scaffolds possess the ability to direct cellular orientation through the presentation of ordered topographical cues and to prevent chronic foreign body response through resorption of the scaffold. However, the mechanical properties of electrospun scaffolds are currently unknown. Thus, the primary aim of the present study was to evaluate the physiomechanical properties of several novel scaffold designs and to determine their suitability for hernia repair applications. Based on prior experimentation, scaffolds possessing at least 20N suture retention strength, 20N tear resistance, and 50N/cm tensile strength will be suitable for hernia repair applications.
METHODS: Six novel scaffolds were designed, fabricated, and tested in our laboratory. The scaffolds were fabricated using various combinations of polymer concentration (10-12%) and flow rate (3.5-10mL/hr). Briefly, poly(ε-caprolactone) (PCL) was dissolved in a solvent mixture, loaded into a syringe, and electrospun onto a planar metal collector, yielding scaffolds with randomly oriented fibers. Physiomechanical properties of each scaffold were subsequently evaluated through scanning electron microscopy, laser micrometry, and mechanical testing (suture retention, tear resistance, and ball burst testing).
RESULTS: Scanning electron micrographs revealed fiber diameters ranging from 1.0±0.1µm (10%PCL, 3.5mL/hr) to 1.5±0.2µm (12%PCL, 4mL/hr). Laser micrometry showed thicknesses ranging from 0.72±0.07mm (12%PCL, 10mL/hr) to 0.91±0.05mm (10%PCL, 3.5mL/hr). Only 2 designs achieved suture retention values above 20N (12%PCL, 10mL/hr and 12%PCL, 6mL/hr), and none of the designs achieved tear resistance values above 20N (range: 4.7±0.9N to 10.6±1.8N). Tensile strengths ranged from 35.27±2.08N/cm (10%PCL, 3.5mL/hr) to 81.76±15.85N/cm (12%PCL, 4mL/hr), with 3 out of 6 designs achieving strengths above 50N/cm (12%PCL, 10mL/hr; 12%PCL, 6mL/hr; 12%PCL, 4mL/hr).
CONCLUSIONS: Two scaffold designs (12%PCL, 10mL/hr and 12%PCL, 6mL/hr) possessed suture retention and tensile strengths appropriate for hernia repair applications. The incorporation of aligned fibers or other patterned designs may improve tear resistance values of the 12%PCL, 10mL/hr and 12%PCL, 6mL/hr scaffold designs for preclinical testing in a hernia repair model.
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