Browsing by Author "Allen, Leah Marie"

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    Generation of Tissue-Engineered Cartilage Constructs in Stirred Suspension Bioreactors
    (2016) Allen, Leah Marie; Sen, Arindom; Hart, David; Matyas, John; Ungrin, Mark; Schmidt, Tannin; Ramirez-Serrano, Alejandro
    Traumatic injuries to articulating joints, such as the knee and hip, can result in the formation of defects within the articular cartilage contained therein. These defects do not heal spontaneously and can initiate a degenerative process, eventually resulting in osteoarthritis (OA). Current cartilage repair options are limited and do not result in the regeneration of durable cartilage. Mesenchymal stem cells (MSCs) isolated from the synovial fluid within joints have an inherent ability to differentiate towards a chondrogenic lineage. Tissue engineered cartilage constructs (TECs) formed from MSCs have been shown to contribute to cartilage repair when implanted into a defect site, thereby providing a potential approach to prevent the onset or the progression of OA. TECs have traditionally been formed in the wells of static culture plates and serum-containing medium. Unfortunately, TECs made in this manner can exhibit variable characteristics which are likely exacerbated by the use of animal-sourced serum in the medium. Therefore, a need still exists to better optimize the generation of uniform TECs to enhance the clinical translatability of this otherwise promising technology. This work investigated the aggregation and culture of human MSCs within suspension bioreactors and serum-free culture conditions for eventual use in filling articular cartilage defects. It also investigated the impact of low-oxygen tension and chondrogenic medium to enhance the MSC differentiation into a chondrogenic phenotype. Expanding on a body of knowledge, this work demonstrated the ability of suspension bioreactors to create a population of aggregates using serum-free culture conditions and non-osteoarthritic human SF-MSCs. Additionally, it demonstrated that the application of low-oxygen tension and chondrogenic growth factors to the suspension bioreactor system is simple. The culture of MSC aggregates in suspension bioreactors under low-oxygen tension resulted in up-regulated gene expression for aggrecan, significantly more collagen/DNA production, and less necrosis on the inside of the aggregates as compared to ambient oxygen tension. The application of chondrogenic medium to the aggregates in the suspension bioreactors resulted in enhanced collagen type-II gene expression and deposition as compared to the static TECs. Although, the overall amount of ECM quantified and staining for glycosaminoglycans was more prominent in the static TECs.