Date of this Version
Tissue engineering, involving the use of three-dimensional (3-D) scaffolds for cell and tissue culture, is a promising technique for establishing in vitro culture models that mimic in vivo environments. In vitro models present ethical and cost advantages over in vivo models, and allow for controlled, mechanistic studies on factors that regulate normal and abnormal tissue development. Alginate, a linear polysaccharide derived from brown algae, has properties that make it a favorable material as a 3-D extracellular matrix for in vitro cell and tissue models. After demonstrating alginate’s tunable physical and chemical properties with respect to gel formation, stiffness, and cellular interactions, alginate hydrogel was employed in two separate culture systems that share in common the ultimate goal of serving as in vitro models of tissue development and function: 1) an in vitro model of pig embryo elongation to develop strategies for improving pregnancy outcomes, and 2) an in vitro model of growth plate cartilage to discover factors necessary for inducing native cartilage architecture for tissue engineering applications. In regards to pig embryo culture, embryos encapsulated within alginate hydrogels exhibited greater survival and morphological changes than non-encapsulated control embryos, along with increased expression of steroidogenic transcripts and estrogen production, consistent with in vivo elongation. For the growth plate model, alginate hydrogels were used for the encapsulation of mouse growth plate chondrocytes in vitro to study the effects of soluble parathyroid hormone (PTH), a signaling factor that regulates growth plate structure and function in vivo, along with the effects of an arginine-glycine-aspartic acid (RGD) peptide conjugated to the alginate. PTH and RGD peptide treatment resulted in decreased collagen X and Indian hedgehog transcript expression in encapsulated chondrocytes, demonstrating the role of these factors on the regulation of chondrocyte hypertrophy in vitro. Overall, information gained from utilizing these in vitro models as research tools can be used to advance the field of developmental biology and enhance tissue engineering therapies for the treatment of degenerative diseases.
Advisor: Angela K. Pannier