title: Chondrocyte culture in three dimensional alginate sulfate hydrogels promotes proliferation while maintaining expression of chondrogenic markers.
abstract: The loss of expression of chondrogenic markers during monolayer expansion remains a stumbling block for cell-based treatment of cartilage lesions. Here, we introduce sulfated alginate hydrogels as a cartilage biomimetic biomaterial that induces cell proliferation while maintaining the chondrogenic phenotype of encapsulated chondrocytes. Hydroxyl groups of alginate were converted to sulfates by incubation with sulfur trioxide-pyridine complex (SO3/pyridine), yielding a sulfated material cross-linkable with calcium chloride. Passage 3 bovine chondrocytes were encapsulated in alginate and alginate sulfate hydrogels for up to 35 days. Cell proliferation was five-fold higher in alginate sulfate compared with alginate (p=0.038). Blocking beta1 integrins in chondrocytes within alginate sulfate hydrogels significantly inhibited proliferation (p=0.002). Sulfated alginate increased the RhoA activity of chondrocytes compared with unmodified alginate, an increase that was blocked by β1 blocking antibodies (p=0.017). Expression and synthesis of type II collagen, type I collagen, and proteoglycan was not significantly affected by the encapsulation material evidenced by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and immunohistochemistry. Alginate sulfate constructs showed an opaque appearance in culture, whereas the unmodified alginate samples remained translucent. In conclusion, alginate sulfate provides a three dimensional microenvironment that promotes both chondrocyte proliferation and maintenance of the chondrogenic phenotype and represents an important advance for chondrocyte-based cartilage repair therapies providing a material in which cell expansion can be done in situ.
authors: 1 Cartilage Engineering+Regeneration, ETH Zürich , Zürich, Switzerland .
authors: Rami
authors: R
authors: Mhanna
authors: Aditya
authors: A
authors: Kashyap
authors: Gemma
authors: G
authors: Palazzolo
authors: Queralt
authors: Q
authors: Vallmajo-Martin
authors: Jana
authors: J
authors: Becher
authors: Stephanie
authors: S
authors: Möller
authors: Matthias
authors: M
authors: Schnabelrauch
authors: Marcy
authors: M
authors: Zenobi-Wong
mesh_terms: D000464:Alginates / Q000737:chemistry*; D000818:Animals; D061249:Batch Cell Culture Techniques / Q000295:instrumentation / Q000379:methods; D040761:Biomimetic Materials / Q000138:chemical synthesis; D002358:Cartilage, Articular / Q000166:cytology* / Q000254:growth & development*; D002417:Cattle; D002454:Cell Differentiation; D049109:Cell Proliferation / Q000502:physiology; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology* / Q000502:physiology*; D020219:Chondrogenesis / Q000502:physiology*; D016326:Extracellular Matrix Proteins / Q000378:metabolism*; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D013431:Sulfates / Q000737:chemistry; D023822:Tissue Engineering / Q000295:instrumentation / Q000379:methods; D054457:Tissue Scaffolds
chemical_list: D000464:Alginates; D016326:Extracellular Matrix Proteins; D006603:Hexuronic Acids; D013431:Sulfates; D020723:Glucuronic Acid