Cyclic strain increases fibroblast proliferation, matrix accumulation, and elastic modulus of fibroblast-seeded polyurethane constructs.
Rapid induction of matrix production and mechanical strengthening is essential to the development of bio-artificial constructs for repair and replacement of load-bearing connective tissues. Toward this end, we describe the development of a mechanical bioreactor and its application to investigate the influence of cyclic strain on fibroblast proliferation, matrix accumulation, and the mechanical properties of fibroblast-seeded polyurethane constructs (FSPC). Human fibroblasts were cultured in 10% serum-containing conditions within three-dimensional, porous elastomeric substrates under static conditions and a model regime of cyclic strain (10% strain, 0.25 Hz, 8 h/day), with and without ascorbic acid supplementation. After one week, the combination of cyclic strain and ascorbic acid resulted in significantly increased construct elastic modulus (>110%) relative to either condition alone. In contrast, cyclic strain alone was sufficient to stimulate significant increases in fibroblast proliferation. Mechanical strengthening of FSPCs was accompanied by increased type I collagen and fibronectin matrix accumulation and distribution, and significantly increased gene expression for type I collagen, TGFbeta-1, and CTGF. These results suggest that strain-induced conditioning in vitro leads to mechanical strengthening of fibroblast/material constructs, most likely resulting from increased collagen matrix deposition, secondary to strain-induced increases in cytokine production.
Webb
Ken
K
Department of Bioengineering, The Keck Center for Tissue Engineering, University of Utah, Salt Lake City, UT 84112, USA.
Hitchcock
Robert W
RW
Smeal
Roy M
RM
Li
Wenhua
W
Gray
Steven D
SD
Tresco
Patrick A
PA
D001205:Ascorbic Acid / Q000494:pharmacology; D019149:Bioreactors; D018929:Cell Culture Techniques; D049109:Cell Proliferation / Q000187:drug effects*; D005109:Extracellular Matrix / Q000187:drug effects / Q000235:genetics; D005347:Fibroblasts / Q000187:drug effects*; D006801:Humans; D008022:Ligaments; D008969:Molecular Sequence Data; D011140:Polyurethanes / Q000494:pharmacology*; D013314:Stress, Mechanical; D013710:Tendons; D023822:Tissue Engineering / Q000379:methods*; D014182:Transplantation, Autologous; D016474:Weight-Bearing / Q000502:physiology
D011140:Polyurethanes; D001205:Ascorbic Acid