Cartilage tissue engineering in the inflammatory milieu.
Abstract: Cartilage tissue engineering aims to repair damaged cartilage tissue in arthritic joints. As arthritic joints have significantly higher levels of pro-inflammatory cytokines (such as IL-1β and TNFα) that cause cartilage destruction, it is critical to engineer stable cartilage in an inflammatory environment. Biomaterial scaffolds constitute an important component of the microenvironment ... read morefor chondrocytes in engineered cartilage. However, it remains unclear how scaffold material influences the response of chondrocytes seeded in these scaffolds under inflammatory stimuli. In the present study, the effects of different material derived scaffolds (silk, collagen, and poly lactic acid (PLA)), structure of scaffolds (pore size), and fabrication methods of scaffolds (aqueous derived (AQ) and hexafluoroisopropanol derived (HFIP) silk scaffolds) were investigated on bovine articular chondrocyte in response to pro-inflammatory cytokines, IL-1β and TNFα. The data indicate that biochemical response of the chondrocytes in inflammatory milieu can be influenced by biophysical properties of scaffold materials; cytokine release kinetics and water uptake abilities. In addition to scaffold material, the role of Nkx3.2, a biochemical factor involved in cartilage formation during development, was investigated on chondrogenesis of human primary cells; human mesenchymal stem cells (hMSCs) and human normal articular chondrocytes (nHACs) and its role on cell response under inflammatory condition. Surprisingly, contrast to its role in mouse mesenchymal stem cell line, C3H10T1/2 in prior studies, transduction of Nkx3.2 inhibited chondrogenesis and redifferentiation of hMSCs and nHACs, respectively. However, knockdown of Nkx3.2 in hMSCs also results in inhibition of chondrogenesis, suggesting that Nkx3.2 is necessary for chondrogenesis but should be maintained in a desired level. Interestingly, Nkx3.2 exhibited protective roles on nHACs in response to inflamed condition by IL-1β, suggesting its possible use for cartilage repair and regeneration in inflamed arthritic joints. Studies on optimal microenvironment, created by appropriate biophysical and biochemical cues, for cartilage tissue in inflammatory milieu will not only help develop new strategies to engineer stronger and more stable cartilage but also contribute to future clinical application.
Thesis (Ph.D.)--Tufts University, 2014.
Submitted to the Dept. of Cell, Molecular & Developmental Biology.
Advisor: Li Zeng.
Committee: Heber Nielsen, David Kaplan, John Castellot, and Alan Grodzinsky.
Keywords: Cellular biology, and Biomedical engineering.read less