Addition of Hyaluronic Acid to Alginate Embedded Chondrocytes Interferes with Insulin-like Growth Factor-1 SignalingIn VitroandIn Vivo

Abstract

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.

Hydrogels for the Repair of Articular Cartilage Defects

“…80 Hyaluronan may stimulate chondrogenesis through interactions with cell surface receptors, 69,81 although conflicting results regarding the combination of hyaluronan with other types of hydrogels indicate a more complex system. 72 For example, the addition of hyaluronan to collagen I hydrogels increased markers of cartilage formation by encapsulated chondrocytes in a subcutaneous implantation model. 73 The addition of hyaluronan to cell culture medium increased deposition of type II collagen and glycosaminoglycans, markers of the cartilage phenotype, by chondrocytes encapsulated in alginate hydrogels, 82 but decreased such markers by chondrocytes encapsulated in collagen hydrogels.…”

“…83 Other studies have shown that the addition of hyaluronan to alginate hydrogels caused an increase in the expression of type I collagen, a marker of fibrous scar-like cartilage formation. 72 Interestingly, this trend was reversed in the presence of exogenous insulin-like growth factor-1 (IGF-1), suggesting a role for hyaluronan in the modulation of IGF-1 signaling by entrapped chondrocytes. 72 Chitosan: Chitosan is prepared by partial N-deacetylation of chitin, derived from the exoskeleton of arthropods, and is structurally similar to the glycosaminoglycans found in cartilage.…”

“…72 Interestingly, this trend was reversed in the presence of exogenous insulin-like growth factor-1 (IGF-1), suggesting a role for hyaluronan in the modulation of IGF-1 signaling by entrapped chondrocytes. 72 Chitosan: Chitosan is prepared by partial N-deacetylation of chitin, derived from the exoskeleton of arthropods, and is structurally similar to the glycosaminoglycans found in cartilage. 87,96 The gelation of chitosan can be induced by ionic or chemical crosslinking.…”

Silk-Fibrin/Hyaluronic Acid Composite Gels for Nucleus Pulposus Tissue Regeneration

“…It has been common practice that two or more biomaterials are combined to utilize the benefits of both. Matrix engineering by adding various components has been successful in producing composite materials, such as fibrin-alginate, 54 HAalginate, 55 and collagen-fibrin. 56 The results indicated the feasibility of the combined matrix gels as supports for cell proliferation without losing their chondrogenic potential.…”

Intervertebral Disk Tissue Engineering Using Biphasic Silk Composite Scaffolds

“…37 HA is a nonsulfated GAG that constitutes a large proportion of cartilaginous ECM. Two or more polymers can be combined into gels to utilize the benefits of each component, such as fibrin-alginate, 48 HA-alginate, 49 and collagen-fibrin. 50 These previous studies demonstrated the capability of combined matrix gels to support cell proliferation without loss of chondrogenic potential.…”