3D Bioprinting Meniscus for Future Tissue Replacement in Osteoarthritis Affected Knee Joints
Examensarbete för masterexamen
Olsson Widjaja, Amanda
Progressive cartilage defects in human knee joints are a worldwide health issue that exposes a great burden on society as well as on single individuals. Sudden traumas to the knees can induce tears in the structures of the joints such as the articular cartilage and the meniscus. Lesions in the cartilage tissue of the knee joints have a high probability to eventuate in osteoarthritis (OA). The emerging technique of 3D bioprinting tissue is a novel approach for cartilage repair and regeneration. The choice of bioink and cell type are important factors that considerably impact the resulting cartilage repair potential after the process of 3D bioprinting. Induced pluripotent stem cells possess the ability to differentiate into almost any cell type and their potential in future regenerative medicine is of great interest. The present study has investigated the possibility of 3D bioprinting chondrocytederived human induced pluripotent stem (iPS) cells into meniscus structures with initiated cartilage regeneration. A combination of nanofibrillated cellulose (NFC) and alginate (A) was used as bioink. At first, the bioink was subjected to optimization to augment printing properties and cell viability during and after bioprinting. The composition of nanofibrillated cellulose and alginate originated from a ratio of 60/40 NFC/A (% w/w) that was compared with one ratio of 48/52 NFC/A (% w/w) and one ratio of 80/20 NFC/A (% w/w). The optimization of bioink involved measurements of printability, rheology, and cell viability. The formation of microtissues enabled differentiation of iPS cells toward extracellular matrix (ECM) producing cells prior to 3D bioprinting. 3D bioprinted menisci, as well as cultured microtissues, were analyzed with LIVE/DEAD assay, immunohistochemical analysis, and quantitative reverse transcription polymerase chain reaction (qRT PCR). The work also comprised an in vivo assay of 3D bioprinted constructs transplanted subcutaneously in mice to enable the evaluation of tissue formation in a realistic milieu. Induced pluripotent stem cells further modified to express green fluorescence protein under the aggrecan promotor have been subjected to a screening of a library of small Food and Drug Administration (FDA) approved molecules. Changes in intensity indicated induction or inhibition of the synthesis of aggrecan. Moreover, the screening highlighted molecules included in the induction or inhibition of aggrecan production. These molecules will be subjected to further investigations to evaluate their possible contribution in future OA-treatments. The prevailing work demonstrates the feasibility of utilizing microtissues formed by iPS cells for the 3D bioprinting of cartilage tissue. The culturing of iPS cells as microtissues has proven to induce differentiation and synthesis of components included in the ECM, both in vitro and in vivo. Simultaneously, the study has included a comparison of three bioinks that resulted in an optimized protocol for the production of the bioink composed of 60/40 NFC/A (% w/w). This optimized bioink fulfilled the requirements of being printable while supporting cell viability.
Alginate , Articular Cartilage , Bioink , Induced Pluripotent Stem Cells , Meniscus , Nanofibrillated Cellulose , Osteoarthritis , Screening , 3D Bioprinting