Technical library

A change in cell morphology can have several biological or technical causes and does not necessarily indicate a problem with the cells themselves.
 
Common reasons include:

• Change in culture medium or supplements: Switching media, using incorrect supplements, or changes in serum concentration can alter cell morphology.
• Cross‑contamination with another cell type: Even low‑level contamination can lead to the appearance of cells with a different morphology.
• Differentiation: Some Normal Human Cells may spontaneously differentiate under certain culture conditions, resulting in altered shape and growth behavior.
• Senescence: As primary cells age in vitro, they may enter senescence, which is often accompanied by noticeable morphological changes (e.g. enlarged, flattened cells).

Normal Human Cells are primary cells and therefore have a finite lifespan in vitro.
After a certain number of population doublings, they will stop proliferating, enter senescence, and eventually die. This is a normal and expected behavior of primary cells.
In addition to their limited lifespan, other factors can accelerate growth arrest or induce cell death, including:

• Incorrect medium preparation (missing or wrong supplements)
• Suboptimal trypsinization conditions
• Microbial contamination (e.g. mycoplasma)
• Excessive passaging combined with high seeding density
• Insufficient gas exchange (e.g. when using non-vented caps)

In principle, all microvascular endothelial cells, including human dermal microvascular endothelial cells (HDMEC), should be able to migrate, proliferate, and form tubes or sprouts in appropriate angiogenesis assays after stimulation with angiogenic factors.
 
Limitations of routine quality control
Migration and tube formation assays are not part of PromoCell’s routine quality control.
Therefore, we cannot guarantee that every HDMEC lot will respond uniformly to angiogenic stimuli.
 
Pre‑screened option
For applications where a defined angiogenic response is critical, PromoCell offers:

• HDMEC pre‑screened for VEGF-responsiveness (C‑12215)

These cells are specifically tested for a positive response to VEGF, providing greater confidence for angiogenesis‑focused assays.

No. PromoCell does not routinely determine the ratio of Human Dermal Lymphatic Endothelial Cells (HDLEC) and Human Dermal Blood Endothelial Cells (HDBEC) within its HDMEC lots.
Based on our experience, the proportion of lymphatic endothelial cells is highly lot-dependent and can vary considerably, typically ranging from approximately 10% to 80%.
In general, juvenile HDMEC (C‑12210) tend to contain a lower proportion of HDLECs, whereas adult HDMEC (C‑12212) typically show a considerably higher proportion of lymphatic endothelial cells.
For applications requiring a pure endothelial cell population, PromoCell also offers Human Dermal Blood Endothelial Cells (HDBEC; C‑12211, C‑12225) and Human Dermal Lymphatic Endothelial Cells (HDLEC; C‑12216, C‑12217), which are derived from HDMEC cultures and subsequently enriched for either blood or lymphatic endothelial cells, respectively.

PromoCell Human Dermal Microvascular Endothelial Cells (HDMEC) are isolated from the dermis of juvenile foreskin or adult skin.
The dermis contains both blood capillaries and lymphatic capillaries. As a result, HDMEC cultures typically comprise a mixture of blood microvascular endothelial cells and lymphatic microvascular endothelial cells, which may display distinct morphologies in culture.
Both cell populations are of endothelial origin and can be identified using established endothelial and lymphatic markers.
Please note: The proportion of blood and lymphatic endothelial cells may vary from lot to lot and is not routinely determined by PromoCell.
 
For applications requiring a more homogeneous endothelial cell population, PromoCell also offers:

• Human Dermal Blood Endothelial Cells (HDBEC; C‑12211, C‑12225)
• Human Dermal Lymphatic Endothelial Cells (HDLEC; C‑12216, C‑12217)

These cell types are derived from HDMEC cultures and subsequently enriched for either blood endothelial cells or lymphatic endothelial cells, respectively.
Our Scientific Support team will be happy to assist you in selecting the most suitable endothelial cell type for your application.

In the detachment protocol for PromoCell’s Macrophage Detachment Solution, Human Serum Albumin (HSA) is recommended as an additive to PBS.
 
Use of FBS instead of HSA

• FBS (or BSA) can technically be used as a substitute for HSA.
• However, this is not recommended, as FBS can cause unwanted immunological stimulation of human macrophages.
• Such stimulation may alter macrophage activation status, gene expression, or downstream functional readouts.

For this reason, HSA is preferred to maintain macrophages in a more defined and physiologically neutral state during detachment.
 
Role of EDTA (2 mM) in the PBS

• EDTA chelates Ca²⁺ and Mg²⁺ ions, which are required for many cell–cell and cell–surface adhesion mechanisms.
• In combination with Ca²⁺/Mg²⁺‑free PBS, EDTA:
  • Further reduces cell–cell adhesion
  • Enhances the anti‑clumping effect
  • Facilitates gentle detachment of macrophages without enzymatic treatment

In general, no. To completely inactivate trypsin, a serum concentration of > 10% FBS is required.
Because most PromoCell Growth Media are serum‑reduced or serum‑free, they do not contain sufficient serum to reliably stop trypsin activity. Therefore, the use of a dedicated trypsin inhibitor, such as Trypsin Neutralizing Solution (TNS), is strongly recommended.

The standard medium recommended by PromoCell for the isolation and expansion of HUVEC, HUAEC, HPAEC, and HSaVEC is Endothelial Cell Growth Medium (C‑22010).
 
Endothelial Cell Growth Medium (C‑22010)

• Contains ECGS (Endothelial Cell Growth Supplement), an extract derived from bovine hypothalamus
• ECGS has mitogenic activity and robustly supports endothelial cell proliferation
• Widely used as a classical, well-established endothelial cell culture medium
• Contains 2% FBS

Endothelial Cell Growth Medium 2 (C‑22011)
For researchers who prefer a more defined formulation, PromoCell offers Endothelial Cell Growth Medium 2. 

• In Endothelial Cell Growth Medium 2, ECGS is replaced by defined recombinant growth factors, including VEGF and IGF, as well as higher levels of bFGF and EGF than in C-22010.
• Like Endothelial Cell Growth Medium, Endothelial Cell Growth Medium 2 also contains 2% FBS.
• To support users who routinely culture endothelial cells in Endothelial Cell Growth Medium 2, PromoCell also offers Growth Medium 2-adapted cells: HUVEC 2, single donor (C‑12206) and pooled HUVEC 2 (C‑12208) are isolated directly in Endothelial Cell Growth Medium 2.

Summary

• Standard choice: Endothelial Cell Growth Medium (C‑22010)
• More defined alternative: Endothelial Cell Growth Medium 2 (C‑22011)
• FBS content: Both media are low-serum media containing 2% FBS
• Both media are suitable for HUVEC culture. The choice depends primarily on whether a classical ECGS-based formulation or a more defined recombinant growth factor composition is preferred.

 

PromoCell Human Dermal Lymphatic Endothelial Cells (HDLEC) are isolated from the dermis of human skin and are delivered at passage 2 (P2).

Tissue localization

• Juvenile donors (C‑12216): Cells are isolated from foreskin.
• Adult donors (C‑12217): The exact localization depends on the type of surgery (e.g. breast, temple, labia).

Detailed information on the specific tissue origin of each cell lot is provided in the Certificate of Analysis (CoA).

Cell characterization
PromoCell HDLEC are quality‑controlled and tested positive for:

• CD31
• Podoplanin
• Ac‑LDL uptake

Recommended culture medium
The recommended medium for culturing HDLEC is Endothelial Cell Growth Medium MV2 (C‑22022).

No. Additional supplementation with FBS or other factors is not necessary.
PromoCell’s Endothelial Cell Growth Medium (C‑22010) is a complete medium for the culture of HUVEC once the SupplementMix has been added.
The SupplementMix already contains:

• FBS (final concentration 2% v/v)
• Recombinant growth factors
• Hormones
• Bovine brain extract (ECGS) and heparin.

Together, these components provide the mitogenic activity required for endothelial cell growth. Adding extra FBS or supplements is therefore not recommended.