title: Effects of cell seeding and cyclic stretch on the fiber remodeling in an extracellular matrix-derived bioscaffold.
abstract: The porcine small intestine submucosa, an extracellular matrix-derived bioscaffold (ECM-SIS), has been successfully used to enhance the healing of ligaments and tendons. Since the collagen fibers of ECM-SIS have an orientation of +/- 30 degrees , its application in improving the healing of the parallel-fibered ligament and tendon may not be optimal. Therefore, the objective was to improve the collagen fiber alignment of ECM-SIS in vitro with fibroblast seeding and cyclic stretch. The hypothesis was that with the synergistic effects of cell seeding and mechanical stimuli, the collagen fibers in the ECM-SIS can be remodeled and aligned, making it an improved bioscaffold with enhanced conductive properties. Three experimental groups were established: group I (n = 14), ECM-SIS was seeded with fibroblasts and cyclically stretched; group II (n = 13), ECM-SIS was seeded with fibroblasts but not cyclically stretched; and group III (n = 8), ECM-SIS was not seeded with fibroblasts but cyclically stretched. After 5 days' experiments, the scaffolds from all the three groups (n = 9 for group I; n = 8 for groups II and III) were processed for quantification of the collagen fiber orientation with a small-angle light scattering (SALS) system. For groups I and II, in which the scaffolds were seeded with fibroblasts, the cell morphology and orientation and newly produced collagen fibrils were examined with confocal fluorescent microscopy (n = 3/group) and transmission electronic microscopy (n = 2/group). The results revealed that the collagen fiber orientation in group I was more aligned closer to the stretching direction when compared to the other two groups. The mean angle decreased from 25.3 degrees to 7.1 degrees (p < 0.05), and the associated angular dispersion was also reduced (37.4 degrees vs. 18.5 degrees , p < 0.05). In contrast, groups II and III demonstrated minimal changes. The cells in group I were more aligned in the stretching direction than those in group II. Newly produced collagen fibrils could be observed along the cells in both groups I and II. This study demonstrated that a combination of fibroblast seeding and cyclic stretch could remodel and align the collagen fiber orientation in ECM-SIS bioscaffolds. The better-aligned ECM-SIS has the prospect of eliciting improved effects on enhancing the healing of ligaments and tendons.
authors.affiliation: Department of Bioengineering, Musculoskeletal Research Center, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
authors.forename: Tan D
authors.initials: TD
authors.lastname: Nguyen
authors.forename: Rui
authors.initials: R
authors.lastname: Liang
authors.forename: Savio L-Y
authors.initials: SL
authors.lastname: Woo
authors.forename: Shawn D
authors.initials: SD
authors.lastname: Burton
authors.forename: Changfu
authors.initials: C
authors.lastname: Wu
authors.forename: Alejandro
authors.initials: A
authors.lastname: Almarza
authors.forename: Michael S
authors.initials: MS
authors.lastname: Sacks
authors.forename: Steven
authors.initials: S
authors.lastname: Abramowitch
mesh_terms: D000818:Animals; D005109:Extracellular Matrix; D005347:Fibroblasts / Q000166:cytology*; D007421:Intestine, Small / Q000166:cytology; D018613:Microscopy, Confocal; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D011817:Rabbits; D013552:Swine; D023822:Tissue Engineering / Q000295:instrumentation* / Q000379:methods*; D054457:Tissue Scaffolds / Q000737:chemistry*
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