title: Mechanical stimulation of tissue engineered tendon constructs: effect of scaffold materials.
abstract: Our group has shown that numerous factors can influence how tissue engineered tendon constructs respond to in vitro mechanical stimulation. Although one study showed that stimulating mesenchymal stem cell (MSC)-collagen sponge constructs significantly increased construct linear stiffness and repair biomechanics, a second study showed no such effect when a collagen gel replaced the sponge. While these results suggest that scaffold material impacts the response of MSCs to mechanical stimulation, a well-designed intra-animal study was needed to directly compare the effects of type-I collagen gel versus type-I collagen sponge in regulating MSC response to a mechanical stimulus. Eight constructs from each cell line (n=8 cell lines) were created in specially designed silicone dishes. Four constructs were created by seeding MSCs on a type-I bovine collagen sponge, and the other four were formed by seeding MSCs in a purified bovine collagen gel. In each dish, two cell-sponge and two cell-gel constructs from each line were then mechanically stimulated once every 5 min to a peak strain of 2.4%, for 8 h/day for 2 weeks. The other dish remained in an incubator without stimulation for 2 weeks. After 14 days, all constructs were failed to determine mechanical properties. Mechanical stimulation significantly improved the linear stiffness (0.048+/-0.009 versus 0.015+/-0.004; mean+/-SEM (standard error of the mean ) N/mm) and linear modulus (0.016+/-0.004 versus 0.005+/-0.001; mean+/-SEM MPa) of cell-sponge constructs. However, the same stimulus produced no such improvement in cell-gel construct properties. These results confirm that collagen sponge rather than collagen gel facilitates how cells respond to a mechanical stimulus and may be the scaffold of choice in mechanical stimulation studies to produce functional tissue engineered structures.
authors: Department of Biomedical Engineering, University of Cincinnati, 2901 Campus Drive, 837 Engineering Research Center, Cincinnati, OH 45221-0048, USA. nirmalvs@email.uc.edu
authors: Victor S
authors: VS
authors: Nirmalanandhan
authors: Matthew R
authors: MR
authors: Dressler
authors: Jason T
authors: JT
authors: Shearn
authors: Natalia
authors: N
authors: Juncosa-Melvin
authors: Marepalli
authors: M
authors: Rao
authors: Cynthia
authors: C
authors: Gooch
authors: Gino
authors: G
authors: Bradica
authors: David L
authors: DL
authors: Butler
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry / Q000378:metabolism; D002478:Cells, Cultured; D024042:Collagen Type I / Q000737:chemistry; D004548:Elasticity; D005260:Female; D005782:Gels / Q000737:chemistry; D045164:Mesenchymal Stem Cell Transplantation; D059630:Mesenchymal Stem Cells / Q000737:chemistry / Q000166:cytology / Q000378:metabolism; D011817:Rabbits; D013314:Stress, Mechanical; D013710:Tendons / Q000737:chemistry / Q000166:cytology / Q000378:metabolism; D013718:Tensile Strength / Q000502:physiology*; D023822:Tissue Engineering / Q000295:instrumentation / Q000379:methods*; D054457:Tissue Scaffolds; D014159:Transducers
chemical_list: D001672:Biocompatible Materials; D024042:Collagen Type I; D005782:Gels