Please join us Tuesday, November 15, 2016, at 3:00 pm in Schiciano Auditorium, Side A, for our first BME Dissertation Award Seminar. Mark Juhas, recipient of the 2016 BME Dissertation Award, will present “Engineering Regeneration: Applications for Tissue-engineered Skeletal Muscle"
Bio: Mark received his doctorate earlier this year for his work in Dr. Nenad Bursac’s lab focused on engineering regenerative skeletal muscle tissues. Prior to coming to Duke, he received a degree in Bioengineering at the University of Pittsburgh. Currently, Mark is searching for a post-doctorate position and welcomes any leads or advice.
Abstract: During my doctoral work in a tissue engineering lab, I worked to develop native-like, three-dimensional skeletal muscle constructs for application as drug screening and development platforms or on-site tissue reconstruction therapy. My optimization of neonatal muscle stem cell (MuSC) preparation and engineered tissue culture resulted in the formation of constructs containing both undifferentiated MuSCs and fully-differentiated myofibers capable of generating force comparable to aged-matched natural muscle. I revealed the benefit of exposing an activated MuSC pool to an environment promoting rapid myogenic fusion events to enhance the homing of the stem cells to their niche on newly-formed myofibers and their subsequent shift to quiescence. To verify the self-repair capacity of the engineered tissue and, specifically, the functionality of the MuSC pool, I developed an in vitro regeneration assay to track myogenesis and structural and functional repair following cardiotoxin-induced injury. Transferring to expanded adult-derived MuSCs, I worked to maintain the MuSC phenotype with passage to generate tissues with a pool of the regenerative cell type. I developed a real-time assay by combining cellular transduction of a genetically-encoded florescent calcium indicator with a live-cell imaging system capable of electrical stimulation and non-invasive mapping to allow monitoring of muscle function to efficiently track repair post-injury. Significantly, I found that the development of a more systemic niche through the introduction of macrophages, essential for natural muscle repair, was necessary to enable regeneration in adult-derived tissues. Through limiting apoptotic events, macrophages reduced myofiber degeneration post-injury allowing MuSCs to proliferate, differentiate, and participate in repair. Coupling a window chamber implantation model that enabled intravital imaging with a florescent calcium sensor, I developed an in vivo platform to non-invasively track engineered tissue vascularization and function in a live animal. With this method, I revealed the capacity of survival, vascularization, and continued myogenesis in neonatal- and adult-derived tissues following implantation and the beneficial role of macrophages in accelerating this process. On-going work includes the search for a mechanistic understanding of macrophage-mediated repair. Preliminary work suggests the immune cell type aids in preventing apoptosis through the reduction of pro-inflammatory factors, mimicking the role of tissue-resident macrophages in natural organs.