Technical library

The optimal calcium concentration for keratinocyte proliferation or differentiation depends on the species and the specific medium formulation used.
To maintain primary human keratinocytes in a proliferative state, low calcium concentrations are generally required, typically in the range of 0.03–0.15 mM. For example, PromoCell Keratinocyte Growth Medium 2 contains 0.06 mM calcium, which supports proliferation.
Increasing the calcium concentration to above 1 mM induces terminal differentiation of keratinocytes and leads to a loss of proliferative capacity.

No, PromoCell does not perform CD90‑based immunomagnetic separation for pericytes.
However, fibroblast contamination can be reliably excluded based on the following criteria:

How fibroblast contamination is ruled out
1. Growth behavior after isolation

• Pericytes require up to 2 weeks before they start proliferating.
• Fibroblasts, in contrast, proliferate immediately after isolation and would rapidly overgrow the culture.
•  Any fibroblast contamination would therefore be clearly detectable shortly after isolation.

2. Phenotypic characterization during Quality Control

• Pericytes are characterized by flow cytometry for CD146 expression.
• Pericytes express CD146, whereas placental fibroblasts do not.
• This marker analysis confirms the identity and purity of the pericyte population.

CD146 (also known as MUC18) is a surface marker that is expressed on pericytes, but it can also be found on mesenchymal stem cells (MSCs) and endothelial cells from large vessels. Importantly, microvascular endothelial cells do not express CD146.
 
Marker combination for pericyte identification
To reliably distinguish pericytes from other cell types, CD146 is used in combination with CD34:

• Pericytes: CD146⁺ / CD34⁻
• Endothelial and hematopoietic cells: CD34⁺

The absence of CD34 expression ensures that the CD146‑positive cells are not of endothelial or hematopoietic origin, allowing a clear identification of pericytes by FACS analysis.
 
Additional pericyte markers
Other markers that have been described for pericytes in the literature include NG2, CD90, α‑smooth muscle actin (α‑SMA), PDGFR‑β.
Please note: These markers are not part of PromoCell's routine Quality Control (QC) testing for pericytes and are therefore not included in the lot-specific Certificate of Analysis (CoA).
 

PromoCell Human Renal Cortical Epithelial Cells (HRCEpC, C‑12660) are isolated from the cortex of the human kidney. The renal cortex is the outer region of the kidney and contains:

• the renal corpuscles,
• the proximal convoluted tubules,
• the distal convoluted tubules, and
• the cortical collecting ducts.

Accordingly, HRCEpC represent a mixed population of epithelial cells originating from cortical nephron segments, including both proximal and distal tubules.

PromoCell human pulmonary fibroblasts (HPF, C‑12360) are isolated from peripheral lung tissue.

Recommended procedure

• Thaw the vial according to the PromoCell protocol.
• Seed part of the cells (5,000 cells/cm²) directly into multiwell plates intended for differentiation.
  • Culture in Preadipocyte Growth Medium until 100% confluency is reached.
  • Then induce differentiation following the recommended protocol.
• Seed the remaining cells (5,000 cells/cm²) into a tissue culture dish for expansion in Preadipocyte Growth Medium.   
  • Trypsinize at subconfluency; if needed, split again:
    • one part for differentiation assays
    • one part to maintain undifferentiated HWP cultures

Important note

• Differentiation capacity may decline after 1-2 passages in vitro.
• Therefore, perform differentiation experiments at early passages.
• Cells at higher passages can still be used for experiments requiring undifferentiated preadipocytes (e.g. proliferation studies).

Yes, to a certain extent, depending on the available donor information for each cell lot.
 
Available donor information
The basic donor information provided by the surgeons typically includes:

• Age
• Gender
• Ethnicity

For many subcutaneous preadipocyte (HWP) donors, additional information is available, such as:

• BMI
• Skin pigmentation
• In some cases, smoking status and/or known diseases (e.g. diabetes)
• Most subcutaneous HWP donors are between ~20 and 70 years of age.

For visceral HWP donors:

• Donors are mostly between ~20 and 85 years of age.
• For many lots, BMI is known, and in some cases additional information such as smoking habits, and/or known diseases (e.g. diabetes or COPD)

Custom donor requirements
If you are looking for specific donor characteristics (e.g. obese BMI, non‑smoker, non‑diabetic, or defined age range), please contact PromoCell Scientific Support. Based on current availability, we can advise on and offer appropriate HWP lots.

PromoCell Normal Human Epidermal Melanocytes (NHEM, NHEM M3) are primary cells. For these cells, we guarantee at least 15 population doublings (PDs) under recommended culture conditions.
In practical terms, this corresponds to approximately 6-8 passages (subcultivations), depending on the seeding density and split ratio used.

However, it is important to note that:

• While proliferation is guaranteed for 15 PDs, we cannot guarantee that the expression or activity of all melanocyte-specific genes remains unchanged over this period.
• Like all primary cells, melanocytes gradually undergo phenotypic changes during in vitro culture.

For this reason, we strongly recommend performing critical experiments at low passage numbers, where the cells most closely reflect their in vivo phenotype.

Mature articular chondrocytes are post‑mitotic cells that produce extracellular matrix components such as collagen types II, IX, and XI, as well as proteoglycans.
After isolation from cartilage and seeding in monolayer culture, chondrocytes re‑enter the cell cycle and begin to proliferate. Following approximately 1-3 weeks in monolayer culture, they gradually start to de‑differentiate and adopt a fibroblast‑like phenotype.
 
Indicators of de‑differentiation
De‑differentiation can be detected by:

• Decreased expression of collagen type II
• Increased expression of collagen type I
• Appearance of the fibroblast marker Thy‑1/CD90

Re‑differentiation

• Chondrocyte re‑differentiation can be induced by switching from conventional 2D monolayer culture to a 3D culture system.

Yes, this is possible in many cases.
All PromoCell Human Chondrocytes (C‑12710) are isolated from either the knee joint or the femoral head.
 
Lot‑specific selection
If you specifically require articular chondrocytes from the knee joint, please contact PromoCell Scientific Support before placing your order. They can:

• check current lot availability, and
• provide you with lot numbers corresponding to the desired anatomical origin.

The exact tissue localization for each lot is documented in the Certificate of Analysis (CoA).