Human Embryonic Stem Cell Therapy for Cardiomyocyte Degeneration Brittney Williams

What is a hESC? Human Embryonic Stem Cells Pluripotent cells capable of differentiating into any cell type Derived before the embryo would normally implant in the uterus They originate from the blastocyst

How do we get hESC? Derived from in vitro fertilized human embryos Culture of pluripotent stem cells Inner cell mass separated from trophectoderm Inner cell mass cells are plated onto cells to support them These cells are fed daily and separated every four to seven days © 2006 Terese Winslow

Why are these so controversial? Moral implication of destroying a human embryo When does life actually start? Is a human embryo a child? Does the destruction of one embryo justify the use as a cure for many people?

What are they used for? Tissue regeneration due to injury Ways to study early development without hurting the resulting child

Cardiomyocyte Repair Myocardial infarction (MI) Heart disease Heart attack Leading cause of death around the world Occurs when cardiomyocyte function is loss Heart disease Leading cause of death in the Western world Cardiomyocyte and mitochondrial function decrease

hESC-derived cardiomyocyte regulation Peroxisome Proliferator-activated Receptor-γ Coactivator (PGC-1) Repression occurs during cardiomyocyte development ROS Control of the ROS levels controls the production of cardiomyocytes As levels are decreased, PGC-1  is knocked down Calcium transient amplitude increased This was discovered through the inhibition of contraction and/or the action potential and calcium transit. Contraction inhibited by Myosin II ATPase inhibitor blebbistatin L-type calcium channel inhibitor nifedipine inhibited the AP and calcium transit.

What does knowing this mean? PGC-1 -dependent development stimulates mitochondrial biogenesis Cardiomyocyte mitochondria are essential to supplying the ATP required during intense heart beating If this function is damaged, there may be consequences Most of what we know is derived from a mouse model These stem cells however are vastly different from humans The ability to see the model in humans gives more insight to mitochondrial regulation Cardiomyocyte identity is linked to the mitochondrial biogenesis phenotype

Use of hESC-derived cardiomyocytes in rats with MI To learn the extent of use for these cells, they must be tested in animal trials Tested in rats with MI to see if myocardial function is improved Immunosuppressed healthy and infarcted rat hearts were injected with one of four things Undifferentiated hESCs hESC-derived cardiomyocytes Noncardiomyocyte hESC derivatives Saline Histological analysis and echocardiography determined the stuctural and functional results

What happens when hESCs are implanted? In Vivo transplant of undifferentiated hESC Results in teratoma-like structures No differentiation into the cardiac lineage In vivo cardiac environment did not enhance hESC cardiomyogenesis Transplantation of hESC-CMs in a healthy heart Grafted cells present however no tetratoma structures Cell grafts consisted of mases of human cells interspersed within myocardium Transplantation of hESC-CMs in the infracted heart Grafted cells present with no tetratoma structure Aligned with host cells with no inflammatory encapsulation Gap junctions could be identified

What happens (cont) Transplant of noncardiomyocyte hESC derivatives Does not change the remodeling process No changes detected Transplant of hESC-CMs improve myocardial performance in the model Grafting ex vivo pre-differentiated hESC-CMs into infracted hearts showed cardiomyocyte survival and integration into the host cell

Citations Embryonic Stem Cells. (n.d.). Retrieved December 02, 2017, from https://stemcells.nih.gov/info/Regenerative_Medicine/2006Chapter1.htm Birket, M. J., Casini, S., Kosmidis, G., Elliott, D. A., Gerencser, A. A., Baartscheer, A., … Mummery, C. L. (2013). PGC-1α and Reactive Oxygen Species Regulate Human Embryonic Stem Cell-Derived Cardiomyocyte Function. Stem Cell Reports, 1(6), 560– 574. https://doi.org/10.1016/j.stemcr.2013.11.008 Caspi, O., Huber, I., Kehat, I., Habib, M., Arbel, G., Gepstein, A., … Gepstein, L. (2007). Transplantation of Human Embryonic Stem Cell-Derived Cardiomyocytes Improves Myocardial Performance in Infarcted Rat Hearts. Journal of the American College of Cardiology, 50(19), 1884–1893. https://doi.org/10.1016/j.jacc.2007.07.054