Cell Sequence and Mitosis Affect Fibroblast Directional Decision-Making During Chemotaxis in Microfluidic Mazes
Directed fibroblast migration is central to highly proliferative processes in regenerative medicine and developmental biology. However, the mechanisms by which single fibroblasts affect each other’s directional decisions, while chemotaxing in microscopic pores, are not well understood.
We explored effects of cell sequence and mitosis on fibroblast platelet-derived growth factor-BB (PDGF-BB)-induced migration in microfluidic mazes with two possible through paths: short and long. Additionally, image-based modeling of the chemoattractant’s diffusion, consumption and decay, was used to explain the experimental observations.
It both cases, the cells displayed behavior that is contradictory to expectation based on the global chemoattractant gradient pre-established in the maze. In case of the sequence, the cells tend to alternate when faced with a bifurcation: if a leading cell takes the shorter (steeper gradient) path, the cell following it chooses the longer (weaker gradient) path, and vice versa. Image-based modeling of the process showed that the local PDGF-BB consumption by the individual fibroblasts may be responsible for this phenomenon. Additionally, it was found that when a mother cell divides, its two daughters go in opposite directions (even if it means migrating against the chemoattractant gradient and overcoming on-going cell traffic).
It is apparent that micro-confined fibroblasts modify each other’s directional decisions in a manner that is counter-intuitive to what is expected from classical chemotaxis theory. Consequently, accounting for these effects could lead to a better understanding of tissue generation in vivo, and result in more advanced engineered tissue products in vitro.
KeywordsMigration Division Diffusion Fibroblast Gradient Chemotaxis PDGF-BB Proliferation Confinement Modeling
The authors also thank Gustavus and Louise Pfeiffer Research Foundation for their gracious funding of our work. Additionally, the authors would like to thank New Jersey Institute of Technology (NJIT)’s McNair Achievement and Provost Summer Research Programs for providing student labor for this project. A fibroblast donation from Prof. Xiaoyang Xu’s laboratory at NJIT’s Department of Chemical, Biological and Pharmaceutical Engineering is greatly appreciated. Lastly, we would like to thank the anonymous reviewer who provided the order of magnitude estimate of the PDGF uptake rate by a cell in our model, which we have included into the Online Appendix.
This study was funded by the Gustavus and Louise Pfeiffer Research Foundation’s Major Investment Grant, while the custom mask aligner was in part funded by NSF I-Corps Site Award #: 1450182.
Conflict of interest
Authors Quang Long Pham, Lydia N. Rodrigues, Max A. Maximov, Vishnu Deep Chandran, Cheng Bi, David Chege, Timothy Dijamco, Elisabeth Stein, Nhat Anh Nguyen Tong, Sagnik Basuray, and Roman S. Voronov declare that they have no conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
Supplementary material 5 (AVI 8015 kb) Supplemental Video 2: Control experiment, showing a correspondence between the simulated PDGF diffusion kinetics (top row) in an empty maze, and those of experimentally-diffused fluorescent dextran (bottom row) with a similar molecular weight. Left column shows the absolute concentration values, in the case of the simulated PDGF, and the fluorescence intensity, in the case of the dextran experiment; right column shows a % difference relative to the steady state values for the same.
- 14.Ellison, D., A. Mugler, M. D. Brennan, S. H. Lee, R. J. Huebner, E. R. Shamir, L. A. Woo, J. Kim, P. Amar, I. Nemenman, A. J. Ewald, and A. Levchenko. Cell-cell communication enhances the capacity of cell ensembles to sense shallow gradients during morphogenesis. Proc. Natl. Acad. Sci. USA 113(6):E679–E688, 2016.CrossRefGoogle Scholar
- 23.Lepisto, J., J. Peltonen, M. Vaha-Kreula, J. Niinikoski, and M. Laato. Platelet-derived growth factor isoforms Pdgf-Aa, -Ab and -Bb exert specific effects on collagen gene expression and mitotic activity of cultured human wound fibroblasts. Biochem. Biophys. Res. Commun. 209(2):393–399, 1995.CrossRefGoogle Scholar
- 25.Levinstone, D., M. Eden, and E. Bell. Similarity of sister-cell trajectories in fibroblast clones. J. Cell. Sci. 59:105–119, 1983.Google Scholar
- 44.Trepat, X., Z. Chen, and K. Jacobson. Cell migration. Compr. Physiol. 2(4):2369–2392, 2012.Google Scholar
- 48.Yan, J., and D. Irimia. Stochastic Variations of migration speed between cells in clonal populations. Technology (Singap World Sci) 2(3):185–188, 2014.Google Scholar