Article Comments - 'Differences in the way a mammalian cell and yeast cells coordinate cell growth and cell-cycle progression'

Critical analysis of the Conlon/Raff model is published

Stephen Cooper — 2004-10-05T00:00:00Z

I would like to draw attention of those interested in the model and experiments of Conlon and Raff to a different view of the subject now published in BMC Cell Biology. The paper is:

Control and maintenance of mammalian cell size

Stephen Cooper

BMC Cell Biology 2004, 5:35 (29 September 2004)

Immediately following this paper is a reply by Conlon and Raff:

Control and maintenance of mammalian cell size: Response

Ian Conlon, Martin Raff

BMC Cell Biology 2004, 5:36 (30 September 2004)

I look forward to hearing from those with questions, comments, critiques, suggestions, thoughts, or additional ideas on the subject. Please write to me at cooper@umich.edu

Why are primary cells smaller than cultured cells of the same type?

Martin C. Raff — 2003-08-11T00:00:00Z

It may be that freshly isolated primary cells are smaller than cells that have been in culture for a while because cells in tissues are exposed to relatively low concentrations of growth factors compared to the situation in culture, where growth factors are usually used at saturating concentrations.

Primary cells increasing in volume

Ian Conlon — 2003-05-08T00:00:00Z

It is indeed quite an interesting observation, and one that we observed in the isolation and purification steps of our cells. Schwann cells (at least in the conditions we use) do not undergo senescence, so the size of cells proliferating in standard (serum-containing) conditions can be stably maintained after the initial purification steps. The size can be modified, however, depending on the conditions that they are proliferated in. Cells proliferating in serum-containing medium are much bigger than cells proliferating in serum-free conditions (see paper), and the size of cells proliferating in serum-free conditions is much more similar to the size of freshly isolated cells. Therefore, I expect the observed increase in size is simply due to the conditions that the cells are put into after isolation. Another complication for Schwann cells is that some of the cells may have started to myelinate at the time of isolation. The isolation procedure results in a loss of the myelinated structure making those cells smaller when freshly isolated than they were in the animal.

Primary cells double their diameter within 1 or 2 passages in vitro.

Hayden Coon — 2003-04-30T00:00:00Z

An excellent paper; interesting, and convincing. I just wondered if the authors had any reaction to the old observation (made independently by Gordon Sato and me) that primary (trypsinized) cells measured at the time of their first plating, double their diameter within 1 or 2 passages. They are pretty stable after that (until senescence sets in). The long term cultured Schwann's cells you have been looking at may well be about 8 times the volume of a freshly liberated (and presumably native) cell. There may be something interesting there...