Interactive effects of surface topography and pulsatile electrical field stimulation on orientation and elongation of fibroblasts and cardiomyocytes
Hoi Ting H. Au, Irene Cheng, Mohammad F. Chowdhury and Milica Radisic
To engineer cardiac tissue, proper structural organization of cardiomyocytes and fibroblasts must be attained. Since functionality of these cells is depended on cellular orientation, it is important to understand what cues govern this. Previous studies have focused on topgraphical, adhesive or electrical cues alone, but this study focuses on the interactive effects of topography and electrical fields on the orientation and elongation of fibroblasts and cardiomyocytes. The authors hypothesized that the same molecular pathways were involved in responding to both cues, and did a pharmacological study to analyze the effects of the actin polymerization and p13k pathways on cell orientation and elongation. To test topographical effects, microabraded coverslips were used with a variation of grain sizes, with half of the coverslip abraded perpendicular to the other half. 3T3 fibroblasts and cardiomyocytes from neotanal rats were used.
The abraded surfaces improved elongation of both fibroblasts and cardiomyocytes, The most significant improvement in comparison to the nonabraded occurred in the surfaces worn with greatest grain size. Electrical field simulation yielded more elongated fibroblasts on abraded surfaces at low voltage, while at higher voltage, the nonabraded surfaces showed a greatly increased elongation, meaning there was no significant difference in elongation between surfaces. The cardiomyocytes showed similar results, with the cells aligning perpendicular to the field lines when the abrasions were also perpendicular. The improved orientation from electrical field stimulation was observed using ImageJ. These results indicated that topographical cues were a stronger determinant of orientation than electrical fields, and also that the same pathways could be involved in responding to both cues. The pharmacological study showed that blocking actin polymerization inhibited the ability of cardiomyocytes to respond to topographical and electrical cues, while the P13K pathway showed reduced alignment and elongation.
I chose this paper because it involved techniques we had done in lab (culture of 3T3s in T75s, live/dead assays, ImageJ, etc) but took them a step further and applied them to a real problem. Effectively engineering cardiac tissue is becoming an increasingly important area of research, and the authors are able to offer suggestions for future improvements, and provide information about the never before studied interaction of various cues on cell orientation.
5 comments:
Did the article explain how pulsatile electrical field stimulation is designed in native tissue? I think it’s important to know this because we are trying to mimicking nature.
How do you think this experiment could be applied to 3-dimensional cell cultures? Also, it would be interesting seeing this experiment used as a control for studying the application of such techniques in vivo.
Since fibroblast and cardiomyocytes respond to both topographical and electrical cues, when we engineer this tissue, which pathway would be easier and more efficient to use? Would we be more likely to use just one pathway or both as an extra measure?
If cells were cultured on an asymmetric topography, such as a mechanical stiffness gradient perhaps, which way would you predict the cells would elongate from the information in this article?
It is interesting that in a study that studies the topographical properties of fibroblasts and cardiomyocytes, that atomic force microscopy is not used (unless I am mistaken about the details of the experiment). AFM is extemely useful for 3D cell cultures, and can be used even when cells are submerged in an original liquid microenvironment.
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