Erin E. Falco, Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD 20742, J. Scott Roth, Department of General Surgery, University of Maryland Medical School, Baltimore, MD 21201, and John P. Fisher, Fischell Department of Bioengineering, University of Maryland, 3238 Jeong H. Kim Building, College Park, MD 20742-2111.
Incisional hernias are a common clinical problem occurring in up to 10% of all patients undergoing abdominal procedures. Primary closure, synthetic biomaterials, as well as xenografts and allografts have been used to treat incisional hernia defects. Despite these approaches, the incidence of hernia recurrence ranges from 24% to 54%. To address this high recurrence rate, we propose an incisional hernia treatment that utilizes a functional biomaterial developed for skeletal muscle regeneration. To this end, the use of a porous cyclic acetal biomaterial (EH network), based on 5-ethyl-5-(hydroxymethyl)-β,β-dimethyl-1,3-dioxane-2-ethanol diacrylate, coated with poly(ethylene glycol) (PEG) to deliver non-viral lipoplexes encoding for insulin like growth factor 1 (IGF-1) and green fluorescent protein (GFP) in vitro was investigated. Porous EH networks were fabricated using a leachable porogen strategy. Briefly, the EHD monomer was combined with 7wt% benzoyl peroxide (BP) in acetone, 70wt% NaCl and the accelerant N,N-dimethyl-p-toluidine (DMT). The slurry was cast in a glass mold to form porous EH sheets. PEG was then reacted onto one side of the EH network using the same radical initiator solution. To characterize these scaffolds, rectangles with 14x3 mm dimensions were made. These rectangles were then placed in 7.4 pH PBS for 1, 4, 8, 14, 21, 28, 56, 84 days. At each time point the scaffolds were weighed and tested in tension to determine the mass lost and yield strength. Since results indicate that these scaffold have clinically relevant degradation times and mechanical strength, additional scaffolds were fabricated, washed and sterilized under UV light overnight. To demonstrate their utility as a plasmid carrier, IGF-1/GFP plasmids were constructed from the IGF-1 gene which was isolated from human skeletal myoblasts. Plasmids were complexed with Lipofectin (Invitrogen) in a ratio of 1:7. Networks were loaded with three different complex concentrations and the complexes were released into growth media. Released plasmids were analyzed for both the plasmid DNA and lipid concentrations using picogreen and an ammonium ferrothiocyanate solution respectively. Bioactivity of the released plasmid was evaluated through the tranfection of human skeletal myoblasts. Results showed that the networks were able to sustain the release of the lipoplexes over a 48 hours time period with the complexes remaining bioactive.