The number of secondary spheres arising from a single primary sphere was counted after one week in culture.
Comparison with the limited experimental results indicates potential for polarization ratio as a diagnostic for primary sphere size.
The polarization ratio at 90° is found to be a monotonic function of primary sphere size and relatively independent of agglomerate size.
Third, Kovykta is purely a gas field and thus is firmly within Gazprom's primary sphere; Sakhalin-2, by contrast, has a large oil component and the oil sector in Russia is more competitive.
For secondary sphere formation, primary sphere cultures were filtered using a 70 μm nylon cell strainer, to retain spheres of larger than 70 μm in diameter.
However, while primary sphere formation was reproducibly increased in a dose dependent manner in established cell lines, secondary sphere formation was not increased and neither sphere formation nor CD44+CD24− cells were increased in MDA-IBC-3 tumors cultured with MSC.
A second generation of sarcospheres was formed with an efficiency of 4.7 ± 0.7% (n = 3), yielding a stem cell frequency similar to that of the primary sphere formation assay.
Amongst other results, it is shown that primary sphere diameter reduction is accompanied by an increase of the geometric standard deviation.
We analyzed the effect of MSC on mammosphere formation as a surrogate marker for TIC and report that MSC increase primary sphere formation from human mammary epithelial cells (HMEC) and from E-cadherin expressing breast cancer cell lines, MCF-7, SUM149, and a novel inflammatory line MDA-IBC-3.
The addition of a Notch4 blocking antibody to primary cultures had no effect on primary sphere formation, but completely abolished secondary mammosphere formation (Fig. 3a,3c,3d,3f,3h).
