02/08/2025
Are you getting quality stem cells? The answer's in the passage.
WHAT YOU NEED TO KNOW
Verifying the passage number of stem cells you're getting is extremely important. It could mean the difference between noticeable results or barely any improvement.
During consultations, always request a sample cell report then ask where the passage number and viability are shown. Request a report (that you can keep) again for the cells you're receiving before your treatment to verify the culture and viability of your batch.
• Passage 3 cells are the best that can be cultured in a lab. They are the purest and youngest which correlates with viability and performance.
• Passage 1 and 2 cells are impure and cannot be used - so watch out for claims that include P1 or P2, they're likely marketing misinformation.
• Anything from Passage 6 onwards significantly lose viability and potency and may not deliver the regenerative results you desire.
THE SCIENCE
When Mesenchymal stem cells are harvested from umbilical chord tissue they're grown and purified in a dish with a nutrient medium that helps the cells multiply.
Stem cells like to stick to the bottom of the dish. Which makes it easier to wash away the non-stem cells that don’t stick, when the nutrient medium is changed.
Each time this process is repeated, it’s called a Passage.
So, Passage 1, or P1 is one round, P3 is 3 rounds, and so on.
And here's where it matters.
• At P1 and P2 the cells are still to impure to use.
• But by P3 you get a clean young batch that has peak potency. That's what we use exclusively since it's the gold standard.
• At P5, the cells are older and their regenerative power noticeably weakens.
• From P6 onward, it becomes a losing game even though the cells have multiplied significantly.
---------
References:
Wu et al. (2014) compared early- vs. late-passage hUC-MSCs and found that by Passage 3, cells still exhibit the classic youthful, spindle-shaped morphology, high proliferation rates, low β-galactosidase (senescence) activity, and robust differentiation potential—traits you need for safe, effective clinical use. In contrast, by Passage 15 the cells are visibly enlarged, flattened, and growth-arrested.
https://pmc.ncbi.nlm.nih.gov/articles/PMC4237101
Liu et al. (2016) (and related reviews) chart a nonlinear decline in functional assays (clonogenicity, cytokine secretion, population doubling) starting around P5–P6, with near-complete senescence by P10–P12. They emphasize that early passages (P1–P3) preserve telomere length and minimal DNA damage—key for translational therapies.
https://pubmed.ncbi.nlm.nih.gov/25339265/
