Types of Matrigel- GFR? hESC qualified?

We’ve had questions recently about the type of Matrigel to use with the Allen Institute for Cell Science cell lines.

To our knowledge… without doing lot testing in your own lab, the “safest” bet would be to use an hESC qualified product (Corning cat#354277). If this product is too expensive for your lab, or you are interested in doing lot testing with hiPSCs that you already have grown and banked in LN2, we recommend testing a few lots of the Growth Factor-Reduced (GFR) Matrigel (Corning cat#354230). As we understand it, the “GFR” means that the growth factors have been quantified and found to be within a certain range by the manufacturer, so the standard of the GFR product (vs. non-GFR) is a little more tightly controlled. That being said, the hESC-qualified products aren’t stated as “GFR”- but that’s ok, because they’ve already been tested on hESCs, so the growth factors were empirically found to be within a good range.

We have found significant variation lot-to-lot with the GFR products, so if you go this route, please do ask Corning to lot test a few batches before you commit to a large purchase. If you’re interested in our lot testing protocol, please reach out to us at cells@alleninstitute.org

If I am reading it correctly the hESC-qualified product from Corning has undergone additional QC testing to make sure that hESCs grown on this matrix for five passages remain undifferentiated based on standard morphology criteria and surface markers, isn’t it? So would they not be taking into consideration/quantifying the growth factors (GF) too in the matrigel?
Or is it done only for the ones classified as GFR-matrigel?
If the hESC-qualified matrigel is more stringent for ESC work wouldn’t they be more tightly controlled or am I messing up the thought process here?