Have a question about one of our products? Check out our technical library for recently asked questions from other scientists around the world.
Technical Library
Recent Entries in Technical Library
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What is the number of primary cells per vial frozen at PromoCell? How can I calculate the number of viable cells and how should I calculate the optimal plating density?
At PromoCell we guarantee for our primary human cells ≥ 500,000 viable cells after thawing. For this, we dispense > 500,000 cells per cryovial before cryopreservation as there will always be a certain percentage of dead cells after freeze/thaw.
In order to know the number of cells that survived the procedure, we defrost a representative number of vials per lot during QC, determine the cell viability using an electronic counting device and then calculate the number of viable cells that can be recovered after thawing. Both numbers – the calculated number of viable cells and the viability – can be found on the lot-specific Certificate of Analysis (CoA) that can be downloaded from our website.
Example: When the CoA indicates 600,000 viable cells and a viability of 80%, this means that the vial actually contains 750,000 cells (viable + dead), 80% thereof (600,000) were viable after thawing in our QC. We do not indicate the total number of cells per vial but just the number of expected viable cells which can be recovered when the recommended thawing protocol is used. You don’t have to calculate any viabilities by yourself.
When the recommended plating density for your cell type is 5,000 – 10,000 cells/cm², then the 600,000 viable cells can be plated e.g. in a T75 (corresponding to 8,000 cells/cm²) or in a T75 + a T25 (corresponding to 6,000 cells/cm²).Related Links and Documents
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I am having problems isolating RNA from peripheral blood MNC pellets. Is there any reason you can think of why this would be?
Problems in obtaining RNA with good yield and purity from mononuclear cells (hMNCs) are quite common. The reason for this is the large amount of free genomic DNA usually contained in MNC preparations. This DNA originates mostly from granulocytes which underwent lysis during the isolation of the MNC. The granulocytes are gone in the final MNC preparation, but their genomic DNA – released during cellular lysis – is still there "sticking" to the MNCs. Solution: Remove DNA prior to RNA purification by a DNase digestion step. Most commercial systems include the option for such a DNase digest.
Related Links and Documents
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What is the exact localization of PromoCell’s HRCEpC? Are the cells isolated from proximal or distal tubuli?
Our Human Renal Cortical Epithelial Cells (C-12660) are isolated from the cortex of the human kidney. The renal cortex is the outer portion of the kidney. It contains the renal corpuscles, the proximal and distal convoluted tubules, and the cortical collecting ducts.
Related Links and Documents
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How does PromoCell determine the phototype of skin tissue donors?
We use a classification system similar but not identical to the Fitzpatrick Skin Classification. The Fitzpatrick classification has six different categories (phototypes I-VI) which correlate with the level of skin pigmentation (melanin) and sunburn following sun exposure. Fitzpatrick I corresponds with the lightest of skin complexions, while Fitzpatrick VI corresponds with the darkest skin.
- I: Pale white skin, blue/hazel eyes, blond/red hair, always burns, does not tan
- II: Fair skin, blue eyes, burns easily, tans poorly
- III: Darker white skin, tans after initial burn
- IV: Light brown skin, burns minimally, tans easily
- V: Brown skin, rarely burns, tans darkly easily
- VI: Dark brown or black skin, never burns, always tans darkly
At PromoCell, we have knowledge of the patients’ skin color (white, brown or black skin), color of eyes and hair, but we don’t have any details about the burning/tanning abilities.
We therefore classify our tissue donors as follows:- Light (comprising phototypes I and II)
- Moderate (comprising phototypes III and IV)
- Dark (comprising phototypes V and VI)
Information on the phototype is available for most cell lots isolated from juvenile or adult skin.
Related Links and Documents
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When subculturing PromoCell’s proliferating HUVEC (T25 flask; C-12250), which TC flask should I use?
A subconfluent T25-flask typically contains between 0.9 and 1.2 million cells corresponding to 36,000-48,000 cells per cm2. It is recommended to count the existing cell number after trypsinization and to calculate the needed number of new flasks.
Recommended seeding density for HUVEC is 5,000-10,000 cells/cm2. This usually corresponds to a split ratio of 1:4-1:6. 1:6 means that you can increase the culture surface by factor 6 (e.g. from 1x T25 to 6x T25 or 2x T75).Related Links and Documents
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At what passage should I induce the differentiation of the SkMC?
For efficient differentiation of our SkMC into myotubes, we recommend to use cells that have undergone a maximum of 4-5 population doublings, i.e. not more than 1 additional subculturing step after thawing the original vial. For more details about differentiation, please see the instruction manual of our Skeletal Muscle Cell Media.
Related Links and Documents
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Where can I find the composition of your basal media?
The formulation of our basal media is proprietary information. If you need to know the concentration of a particular component for your experiments, please contact the PromoCell Technical Customer Service.
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What chondrocyte structures are stained using Alcian Blue? Can I use this staining method for chondrocytes in monolayer cultures?
Alcian Blue stains the extracellular matrix of chondrocytes, e.g. cartilage-specific aggrecan and other glycosaminoglycans. To our knowledge, chondrocytes only express aggrecans when grown in 3-D culture and not in 2-D culture.
To detect cartilage specific markers in monolayer culture, it is recommended to perform immunofluorescence detection of collagen type II.Related Links and Documents
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Does PromoCell recommend growing their osteoblasts on type I collagen?
PromoCell generally culture their HOB on uncoated tissue culture dishes. It is possible however to grow them on collagen type I- or fibronectin-coated dishes as well. Please note: The type of extracellular matrix used may influence the expression of certain genes (e.g. integrins) and thereby affect cellular metabolism. Therefore, we recommend to always use the same type of coating matrix for a whole set of experiments.
Related Links and Documents
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How do I best isolate RNA from PromoCell cell pellets (C-14**)?
There are two options for isolating RNA from cells stored in RNAlater Solution:
1) The solution is removed from the cells prior to extraction by centrifugation at 5,000 x g for 10 minutes at 4°C.
Note: Because of the density of RNAlater® solution, greater centrifugal forces are required to spin down the cells.2) If no pellet is visible after centrifugation, RNA can also be purified directly from the RNAlater® solution. This can be done by adding 2 ml of 10x lysis buffer, and proceeding normally.
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