Technical library

Yes. The PromoCell Macrophage Detachment Solution has been successfully used to detach mouse bone marrow‑derived macrophages, as reported by Campuzano et al. in the Journal of Immunology (2020). In this study, macrophages were detached by incubation with the solution for 40 minutes at 4°C.

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.

For cytokine release studies, non-activated (polarized) macrophages are the recommended negative control.
Because macrophages constitutively secrete certain cytokines, the effects of M1 or M2 activation should always be assessed relative to a corresponding non-activated M(-) control. To ensure meaningful comparisons, the control cells should be cultured and handled under the same conditions as the activated macrophages, with the activation stimulus being the only difference.

No. PromoCell does not provide data on cytokine profiles or extended marker expression of M1/M2 macrophages after activation.

• PromoCell does not analyze or supply functional readouts such as cytokine secretion profiles following activation.
• No additional characterization data beyond the scope of standard quality control (QC) are provided.

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.

PromoCell has not directly tested the plating of cryopreserved macrophages in 96‑well plates.
However, based on feedback from customers, our macrophages have been successfully used in 96‑well plate formats in their experimental setups.

No. α‑SMA negativity is not an intrinsic or universal property of endothelial cells.
Scientific findings from multiple research groups, as well as PromoCell’s own internal data, indicate that the presence or absence of α‑SMA is not a reliable marker to define the composition of an endothelial cell population. Endothelial cells can express α‑SMA under certain conditions, and its expression may vary depending on extrinsic factors, such as culture conditions or environmental cues.
For this reason, lot‑specific α‑SMA values are not considered meaningful quality criteria and are not reported in PromoCell Certificates of Analysis (CoAs).

Von Willebrand factor (vWF) is commonly associated with endothelial cells, as it is stored in Weibel-Palade bodies (WPBs), which are endothelial‑specific secretory granules.
However, there are important limitations to consider:
 
vWF expression is highly dynamic
Its expression strongly depends on culture conditions, particularly:

• Cell confluence
• Passage number
• Overall cellular activation state

Association with confluence rather than identity
WPBs containing vWF are more closely linked to the formation of a confluent endothelial monolayer than to endothelial cell identity per se.
Because of this variability, vWF is not a robust standalone quality control marker for endothelial cells, especially when comparing different lots or culture conditions. For these reasons, routine testing of vWF expression for every endothelial cell lot is not strictly necessary and should be interpreted with caution.
 
Further reading
Howell et al.; Mol Membr Biol. 2004 Nov-Dec;21(6):413

Yes. Accutase Solution can be thawed, aliquoted, and refrozen.
 
Handling recommendations
Thawing:

• Thaw overnight in the refrigerator, or
• Place the bottle in a container of cold tap water.
• Do not thaw in a 37°C water bath.

Aliquoting and storage:

• After thawing, Accutase can be aliquoted and refrozen for later use.

Stability after thawing:

• Once thawed, Accutase is stable for at least 2 months at 4-8°C, provided it is stored promptly after use.

Yes. CD34⁺ progenitor cells can be re‑frozen after expansion in PromoCell Hematopoietic Progenitor Cell Expansion Medium XF.
After successful amplification, the expanded cells may be cryopreserved using an appropriate freezing medium (e.g. Cryo-SFM Plus, C-29920) and protocol, allowing their use in subsequent experiments at a later time.