Contact-mediated cell-assisted cell proliferation in a model eukaryotic single-cell organism: an explanation for the lag phase in shaken cell culture.
In cell culture, when cells are inoculated into fresh media, there can be a period of slow (or lag phase) growth followed by a transition to exponential growth. This period of slow growth is usually attributed to the cells' adaptation to a new environment. However, we argue that, based on observations of shaken suspension culture of Dictyostelium discoideum, a model single-cell eukaryote, this transition is due to a density effect. Attempts to demonstrate the existence of implicit cell signaling via long-range diffusible messengers (i.e., soluble growth factors) through cell-medium separation and microfluidic flow perturbation experiments produced negative results. This, in turn, led to the development of a signaling model based on direct cell-to-cell contacts. Employing a scaling argument for the collision rate due to fluid shear, we reasonably estimate the crossover density for the transition into the exponential phase and fit the observed growth kinetics.
Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY 14853, USA.
Carl
C
Franck
Wui
W
Ip
Albert
A
Bae
Nathan
N
Franck
Elijah
E
Bogart
Thanhbinh Thi
TT
Le
D000818:Animals; D018929:Cell Culture Techniques; D002453:Cell Cycle; D049109:Cell Proliferation; D002478:Cells, Cultured; D003260:Contact Inhibition / Q000502:physiology; D004023:Dictyostelium / Q000166:cytology / Q000254:growth & development / Q000502:physiology; D005057:Eukaryotic Cells / Q000166:cytology* / Q000502:physiology*; D007700:Kinetics; D008954:Models, Biological