The influence of collagen-glycosaminoglycan scaffold relative density and microstructural anisotropy on tenocyte bioactivity and transcriptomic stability.
Biomaterials for orthopedic tissue engineering must balance mechanical and bioactivity concerns. This work describes the fabrication of a homologous series of anisotropic collagen-GAG (CG) scaffolds with aligned tracks of ellipsoidal pores but increasing relative densities (ρ(∗)/ρ(s)), and we report the role scaffold relative density plays in directing tenocyte bioactivity. Scaffold permeability and mechanical properties, both in tension and compression, were significantly influenced by relative density in a manner predicted by cellular solids models. Equine tenocytes showed greater levels of attachment, metabolic activity, soluble collagen synthesis, and alignment as well as less cell-mediated scaffold contraction in anisotropic CG scaffolds of increasing relative density. Notably, the lowest density scaffolds experienced significant cell-mediated contraction with associated decreases in tenocyte number as well as loss of microstructural integrity, aligned contact guidance cues, and preferential tenocyte orientation over a 14 day culture period. Gene expression analyses suggested tenocyte de-differentiation in the lowest density scaffold while indicating that the highest density scaffold supported significant increases in COMP (4-fold), tenascin-C (3-fold), and scleraxis (15-fold) expression as well as significant decreases in MMP-1 (9-fold) and MMP-13 (13-fold) expression on day 14. These results suggest that anisotropic scaffold relative density can help to modulate the maintenance of a more tendon-like microenvironment and aid long-term tenocyte transcriptomic stability. Overall, this work demonstrates that relative density is a critical scaffold parameter, not only for insuring mechanical competence, but also for directing cell transcriptomic stability and behavior.
Department of Chemical & Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
Steven R
SR
Caliari
Daniel W
DW
Weisgerber
Manuel A
MA
Ramirez
Douglas O
DO
Kelkhoff
Brendan A C
BA
Harley
D000818:Animals; D016880:Anisotropy; D001672:Biocompatible Materials / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D002356:Cartilage / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D002417:Cattle; D002470:Cell Survival / Q000187:drug effects; D003094:Collagen / Q000096:biosynthesis / Q000378:metabolism*; D005109:Extracellular Matrix / Q000187:drug effects / Q000378:metabolism; D006025:Glycosaminoglycans / Q000378:metabolism*; D020782:Matrix Metalloproteinases / Q000235:genetics; D055595:Mechanical Phenomena; D010539:Permeability; D010641:Phenotype; D016062:Porosity; D019063:Tenascin / Q000235:genetics; D013710:Tendons / Q000166:cytology*; D023822:Tissue Engineering; D054457:Tissue Scaffolds / Q000737:chemistry*; D059467:Transcriptome / Q000187:drug effects*
D001672:Biocompatible Materials; D006025:Glycosaminoglycans; D019063:Tenascin; D003094:Collagen; D020782:Matrix Metalloproteinases