Xenogeneic cardiac extracellular matrix (cECM) scaffolds for reconstructive heart surgery applications have potential to overcome the limitations of current clinically utilized patch materials. A potentially ideal cECM scaffold would be immunologically acceptable while preserving the native cECM niche. Production of such a scaffold necessitates removal of cellular and antigenic components from cardiac tissue while preserving cECM structure/function properties. Existing decellularization methodologies predominantly utilize denaturing detergents which might irreversibly alter cECM material properties. To overcome the potential deficiencies of current approaches, the effect of sarcomere relaxation and disassembly on resultant cECM scaffold cellularity was investigated. Additionally, the ability of sequential differential protein solubilization (Antigen Removal-AR) to reduce cECM scaffold antigenicity was examined. Sarcomeric relaxation and disassembly were necessary to achieve scaffold acellularity. All groups in which AR was employed displayed statistically significant decreases in residual antigenicity regardless of their degree of acellularity. Structural, biochemical and mechanical properties were preserved using the developed sarcomeric disassembly/AR approach, while sodium dodecyl sulfate (SDS) decellularization significantly altered cECM properties. Additionally, AR cECM was compatible with Mesenchymal Stem Cell (MSC) recellularization and was transformed into adipose tissue after 12 weeks in a subcutaneous mouse in vivo model, displaying a constructive remodeling response reminiscent of the negative immunological allograft control group. In contrast, SDS resulted in a chronic inflammatory response similar to the xenogeneic rat native cardiac tissue control group (Xeno). Implantation of mouse MSC-seeded constructs resulted in a positive immunomodulatory effect in the recellularized native group (Xeno-R) but paradoxically triggered a persistent chronic inflammatory response in the recellularized AR group (AR-R) that resembled Xeno group. This work demonstrates the importance of solubilizing both cellular elements and antigenic components in a stepwise manner for production of a potentially ideal cECM scaffold that could be used in immunocompetent recipients. Importantly, it solidifies the concept that the immunomodulatory potential of MSCs may be harnessed only at the appropriate context and may have implications for future tissue engineering and regenerative medicine applications.
|Advisor:||Griffiths, Leigh G.|
|Commitee:||Baar, Keith, Chiamvimonvat, Nipavan|
|School:||University of California, Davis|
|Department:||Molecular, Cellular and Integrative Physiology|
|School Location:||United States -- California|
|Source:||DAI-B 77/10(E), Dissertation Abstracts International|
|Subjects:||Biology, Biomedical engineering|
|Keywords:||Cardiac tissue engineering, Decellularization, Extracellular matrix, Immunomodulation, Mesenchymal stem cells, Xenogeneic scaffold|
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