Discipline: Technology and Engineering
Subcategory: Biomedical Engineering
Jessica Trinh - University of Washington
Danon disease is a condition caused by a mutation on the LAMP2 gene located in the X chromosome. Individuals carrying the disease typically possess hypertrophic cardiomyopathy, in which thickened heart cardiomyocytes limit blood flow. The deficiency in blood flow due to weakened heart muscles can lead to complications in cardiac function resulting in death. In collaboration with the Song lab at the University of Colorado, we aim to better understand the differences in contractile function between healthy cardiomyocytes and those from individuals with Danon disease. The Song lab obtained primary adult cells from two control groups: healthy individuals without cardiac problems and three diseased groups consisting of people suffering from Danon disease. The patient cells were used to generate induced pluripotent stem cells (iPSC), from which they derived cardiomyocytes that possess genetic information of the original donor. The Sniadecki lab has the technology to make micropost substrates from polydimethylsiloxane (PDMS), using a soft lithography process. The iPSC-cardiomyocytes were seeded onto the microposts where they contract and cause underlying posts to deflect. Videos were captured at the tips of the microposts underneath the beating cells, to record the post deflection over time. A still image was taken at the bottom of the microposts to determine the relative deflection of each post. Based on the data obtained, we were able to measure contractile forces produced by the iPSC-cardiomyocytes using beam bending theory. For this experiment, we used microposts with following dimensions: height = 4.14 μm, diameter = 1.75 μm, and center-to-center spacing of 6 μm. These dimensions gave each post a stiffness = 56 nN/μm, which was used to calculate the force. We hypothesized that the diseased cardiomyocytes would produce lower contractile forces than the control cells. The results demonstrated no significant differences in contractile function between the control and diseased groups. However, the data compiled is reflective of adolescent single cell cardiomyocytes and maturation of the cells must be taken into account. The disease typically takes 1 to 3 decades for the phenotype to be expressed in individuals with the LAMP2 mutation. To further test the contractile force, we will test how nutrient depletion and humoral stimulation affect mitochondrial function. Due to the LAMP2 mutation, we suspect mitochondrial function impairment is affecting cell autophagy and quality control of cells. By introducing stressors such as glucose starvation, we hope to understand more of the mechanisms resulting from the genetic mutation on LAMP2, characterized by Danon disease. We hope this study contributes to understanding the effect of Danon disease on the contractile function of cardiomyocytes. This work would exemplify a methodology to investigate cardiac disease modeling and treatments.
Funder Acknowledgement(s): Nathan J. Sniadecki, Andrea Leonard, the Cell Biomechanics Lab, in addition to Kunhua Song, Congwu Chi, and Yingqiong Cao of the Song Lab from the University of Colorado.
Faculty Advisor: Nathan J. Sniadecki, firstname.lastname@example.org
Role: My role in this research project is substrate preparation for cell culture and data analysis. For substrate preparation, I needed to fabricate microposts, which are fabricated from polydimethyl silicon. Microposts are casted from negative molds of posts, which are fabricated from master molds. The microposts have dimensions which would result in a stiffness, then used to measure contractility in diseased and controlled cells.