archives@tulane.edu / 1 / Jessica Margaret Mary Motherwell

München, Techn. Universiẗat, Diss., 2007.

Bone is a dynamic tissue that in some cases, due to fractures, infection or interruption of blood supply, does not repair completely, leading to bone loss; therefore it is necessary to recur to bone grafts. However, bone grafts (i.e.autografts) may require additional surgery and present risks associated with potential disease transmission from donor to recipient (i.e.allografts). The limitations of these grafts have encouraged the pursuit of engineered alternatives that are based on the synchronous interplay between biomaterials, biological macromolecules and cells. 3-D gelatin-based scaffolds were prepared and evaluated for their ability to promote osteogenesis. Three types of gelatin based scaffolds were prepared via the crosslinking of gelatin B with glutaraldehyde or EDC/NHS in the presence or absence of PLG . The porosity and pore size of the scaffolds were controlled by varying the freeze-drying temperature (-20°C and -80°C). To promote osteogenesis, human stromal MIAMI cells were incorporated in the scaffolds. Results demonstrated MIAMI cells grew and spread actively throughout gelatin and gelatin/PLG scaffolds after 14 days of incubation. The rate of osteogenic activity was confirmed through histochemical staining for alkaline phosphatase and calcium. Mineral deposition was increased in the gelatin scaffold as opposed to the gelatin/PLG scaffold after at day 35.

The ability of articular cartilage to self-repair after injury is limited due to the nature of the tissue. Biological repair is a promising treatment for cartilage injuries but success is limited by the ability to integrate with native cartilage. An in vitro model can be developed to investigate factors that regulate cartilage repair. A tissue engineered cartilage construct was placed into a host bovine osteochondral explant and cultured for 4 and 8 weeks. This same construct was cultured under stimulated and unstimulated conditions for 2 and 4 weeks. Autologous osteochondral implants served as controls. Integration was evaluated histologically, biochemically, biomechanically and for changes in gene expression. The tissue-engineered implants integrated over time whereas the autologous implants did not. Mechanical stimulation and prolonged incubation improved integration between implant and host tissue. An in vitro model of repair-native cartilage integration has been developed which is suitable for further study of tissue integration.

The ability of articular cartilage to self-repair after injury is limited due to the nature of the tissue. Biological repair is a promising treatment for cartilage injuries but success is limited by the ability to integrate with native cartilage. An in vitro model can be developed to investigate factors that regulate cartilage repair. A tissue engineered cartilage construct was placed into a host bovine osteochondral explant and cultured for 4 and 8 weeks. This same construct was cultured under stimulated and unstimulated conditions for 2 and 4 weeks. Autologous osteochondral implants served as controls. Integration was evaluated histologically, biochemically, biomechanically and for changes in gene expression. The tissue-engineered implants integrated over time whereas the autologous implants did not. Mechanical stimulation and prolonged incubation improved integration between implant and host tissue. An in vitro model of repair-native cartilage integration has been developed which is suitable for further study of tissue integration.

Whole-organ perfusion decellularization was performed with rat hearts on a modified chromatography apparatus. Analysis of the flow properties and effluent material over time provided insights into the decellularization process, and allowed non-destructive testing of perfused cardiac tissue. Decellularized matrices were stored for up to 1 year at -80°C and then conditioned to remove residual detergent and cryoprotectant. Tissue was reseeded with canine blood outgrowth endothelial cells (BOECs) and cultured in an autoclavable closed-circuit bubble-free reactor. The entire process was considered in the context of eventual scale-up in equipment design, the use of disposable components, and extracellular matrix (ECM) product storage. Tissue patch substrates for cell growth were studied for cytotoxic effects towards process development. Decellularization protocols were compared. Extracellular matrix derived coatings and gels were investigated as process assays and potential cell delivery vehicles. Peracetic acid and UV disinfection were tested. Micronized ECM carriers were developed for scalable culture, with considerations to carrier morphology, cell attachment, and egress. Micronized ECM carriers were tested with a novel in vitro assay to simulate the support of adherent cells for gene-modified cell therapy.

No description available.

Thesis (Ph. D.)--School of Biomedical Engineering, Georgia Institute of Technology, 2004. Directed by Timothy M. Wick. / Vita. Includes bibliographical references (leaves 182-195).

Thesis (Ph.D.)--Drexel University, 2009. / Includes abstract and vita. Includes bibliographical references (leaves 160-177).

Zugl.: München, Techn. Universiẗat, Diss., 2009.