June 19, 2014

As the widespread therapeutic use of stem cells moves closer to reality, I just fasten my seatbelt a little tighter. An exciting time for stem cells and their scientist stalkers, a recent paper shows the regeneration of damaged monkey hearts by human embryonic stem cell-derived cardiomyocytes.
 
Human embryonic stem cells (hESCs) can be programmed to differentiate into countless different cell types. hESCs are already being tested in humans to treat retinal diseases and spinal cord injuries. hESCs can be differentiated into cardiomyocytes, or heart muscle cells, to potentially repair a damaged heart after injury or failure. In a recent study, Chong and colleagues used hESC-derived cardiomyocytes (hESC-CMs) to repair injured monkey hearts, which are more comparable to human hearts in size and number of cardiomyocytes required. After first developing techniques for producing large, clinical-scale cryopreserved batches of hESC-CMs, Chong and colleagues found that these cells successfully re-muscularized the injured monkey hearts. The electromechanical coupling between host heart tissue and hESC-CM graft tissue was successful, yet non-fatal arrhythmias were observed. In the images above, host vessels (red) extend into graft tissue (white, boxed region and higher magnification below) and are able to successfully perfuse the graft tissue.

Chong, J., Yang, X., Don, C., Minami, E., Liu, Y., Weyers, J., Mahoney, W., Van Biber, B., Cook, S., Palpant, N., Gantz, J., Fugate, J., Muskheli, V., Gough, G., Vogel, K., Astley, C., Hotchkiss, C., Baldessari, A., Pabon, L., Reinecke, H., Gill, E., Nelson, V., Kiem, H., Laflamme, M., & Murry, C. (2014). Human embryonic-stem-cell-derived cardiomyocytes regenerate non-human primate hearts Nature, 510 (7504), 273-277 DOI: 10.1038/nature13233
Adapted by permission from Macmillan Publishers Ltd, copyright ©2014

May 3, 2012

Where did you come from? Understanding the answer to this question helps you get a grasp on who you are currently, and who you are becoming. Whoa, that was deep…enough of that crap! A recent paper puts the psychotherapy treatment on cells in the developing heart and adds to our understanding of where they are from.

The change that takes place in a developing heart is astounding—a simple tube structure with a single layer of cardiac muscle cells called cardiomyocytes must develop into a complex adult structure. How the early cardiomyocytes divide and move around to form the adult heart is difficult to map out due to their dynamic behavior and their location in a tissue that is difficult to image. A recent paper describes the use of a recently-developed technology called Brainbow, in which different cells can be labeled with about 90 different colors. Using Brainbow techniques, Gupta and Poss were able to track the division and movement of individual cardiomyocytes in the developing zebrafish heart, and found that the cells expand the cardiac tissue in patches of various sizes and shapes. By using clonal dominance as a mechanism for tissue expansion, the process is reminiscent of stem cells. The image above shows the surface of the ventricular side of a developing heart, each color representing a different clonal patch that arose from a single cardiomyocyte.

Gupta, V.; Poss, K. (2012). Clonally dominant cardiomyocytes direct heart morphogenesis Nature, 484 (7395), 479-484 DOI: 10.1038/nature11045

Adapted by permission from Macmillan Publishers Ltd, copyright ©2012