Technical library

PromoCell is using a pan-cytokeratin antibody rather than a specific type of cytokeratin for the quality control of our keratinocytes.

PromoCell guarantees more than 500,000 viable cells per vial.
To reliably meet this guarantee, more than 500,000 cells must be frozen at the time of cryopreservation. This is necessary because the post‑thaw viability cannot be determined at the moment of freezing.

Additional factors
For technical and organizational reasons, the initial cell number may vary between different lots. As a result:

• Two lots with the same post‑thaw viability may still contain different absolute cell numbers.
• The actual number of cells in a vial may therefore be significantly higher than 500,000.

 

Yes, there is a reference (Campuzano et al.; J Immunol. 2020 Jun 15;204(12):3296) where bone marrow-derived macrophages from mouse were detached using our Macrophage Detachment Solution (40 minutes at 4°C).

Further Information

Campuzano et al.; J Immunol . 2020 Jun 15;204(12):3296

PromoCell Normal Human Epidermal Keratinocytes (NHEK) from juvenile donors are isolated from both the outer (cutaneous) epidermis and the inner (mucosal) epidermal layer of the foreskin.
As a result, each vial contains a mixed population of mucosal and cutaneous keratinocytes.

Even non-activated macrophages do release a certain amount of cytokines. Furthermore, you would have to be sure that the release of a certain cytokine is a direct consequence of the activation. Therefore, we do not think it is possible to have a general negative control for the cytokine release.

No, we do not provide data about the cytokine profile of our M1/M2 macrophages after activation and we do not provide any further data beyond the scope of our quality control.

Representative M1 and M2 macrophage activation conditions are summarized in Table 1 of the corresponding PromoCell Application Note.
This table lists the published differentiation factor/activator combinations to serve as a basic guidance. Specific effects of activation on macrophages should be tested in comparison to the most appropriate non-activated M(-)-baseline variant as a control.

We did not plate the cryo-macrophages in 96-well plates. However, we heard from other customers that they have successfully used our macrophages in this kind of plate.

Scientific findings from different groups, as well as our own results indicate that the presence or absence of α-SMA is not a valid indicator for the composition of a given cell population. Research findings and our inhouse data suggest that endothelial cells are not α-SMA-negative under all circumstances. α-SMA negativity is not an intrinsic property of endothelial cells but can vary depending on extrinsic influences. Lot-specific values for α-SMA in our Certificates of Analysis (CoAs) are therefore not considered meaningful.

Further Information

Ando et al.; Am J Physio l. 1999 May;276(5):H1755-68

Lu et al.; Stem Cells Dev . 2004 Oct;13(5):521-7

Azuma et al.; Biochem Biophys Res Commun . 2009 Mar 13;380(3):620-6

Frid et al.; Circ Res . 2002 Jun 14;90(11):1189-96

Kovacic et al.; J Am Coll Cardiol . 2019 Jan 22;73(2):190-209

Jones et al.; Am J Respir Cell Mol Biol . 1999 Apr;20(4):582-94

Ma et al.; Front Cell Dev Biol . 2020 Apr 21;8:260

Kocher and Madri; In Vitro Cell Dev Biol . 1989 May;25(5):424-34

Amberger et al.; FEBS Lett . 1991 Aug 5;287(1-2):223-5

Secretory granules called Weibel-Palade bodies (WPBs) containing Von Willebrand factor (vWF) are more linked to the formation of a confluent endothelial monolayer. Research shows that vWF expression is dynamic and highly dependent on the cell culture conditions such as confluence and passage number. Therefore, having vWF as a quality control marker for each lot of ECs is not really necessary.

Further Information

Howell et al.; Mol Membr Biol. Nov-Dec 2004;21(6):413-21