Addition of hyaluronic acid to alginate embedded chondrocytes interferes with insulin-like growth factor-1 signaling in vitro and in vivo.
The development of an engineered tissue requires a clear understanding of the interactions between the individual components. In this study, we investigated how the addition of hyaluronic acid (HA) to a cartilage tissue engineered scaffold alters chondrocytic expression, and specifically the expression of insulin-like growth factor-1 (IGF-1) signaling molecules. Bovine chondrocytes were embedded (7 million cells/mL) in 2.0% w/v alginate hydrogels containing varying HA concentrations (0, 0.05, 0.50, and 5.00 mg/mL). In vitro constructs were cultured with exogenous IGF-1, and gene expression was monitored at days 1, 4, and 8 for IGF-1, IGF-1 receptor (IGF-1R), IGF binding protein 3 (IGFBP-3), type II collagen and type I collagen. In vivo constructs were precultured for 24 h with exogenous IGF-1 before being implanted subcutaneously in severe combined immunodeficient mice; samples were analyzed using histology at days 7, 14, and 21. Results indicate that, with the addition of high levels (5.00 mg/mL) of HA, IGF-1 can become entrapped within the matrix and therefore interfere with the delivery of IGF-1 to chondrocytes. In vitro and in vivo data showed that increasing the concentration of HA in an alginate hydrogel can decrease chondrocyte IGF-1 expression. IGF-1R expression did not change with HA concentration, and the addition of any HA did not significantly alter IGFBP-3 expression. Chondrocytes continuously expressed phenotypic type II collagen in vitro and in vivo throughout the study for all the groups. However, for all the HA concentrations investigated, chondrocytes showed more of a fibroblastic phenotype, as indicated by greater expression of type I collagen than with no HA, in vitro and in vivo. In conclusion, these results indicate that HA interferes with the delivery of IGF-1 to chondrocytes, affecting the endogenous expression of IGF-1 signaling molecules and the resulting chondrocyte phenotype, and therefore demonstrating the critical effect of biomaterial scaffolds on encapsulated cell function.
Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, Maryland 20742, USA.
Diana M
DM
Yoon
Shane
S
Curtiss
A Hari
AH
Reddi
John P
JP
Fisher
D000464:Alginates / Q000737:chemistry*; D000818:Animals; D002417:Cattle; D018929:Cell Culture Techniques / Q000379:methods; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D020219:Chondrogenesis / Q000187:drug effects / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D006820:Hyaluronic Acid / Q000008:administration & dosage*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D051379:Mice; D016513:Mice, SCID; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D023822:Tissue Engineering / Q000379:methods*
D000464:Alginates; D006603:Hexuronic Acids; D007334:Insulin-Like Growth Factor I; D020723:Glucuronic Acid; D006820:Hyaluronic Acid