Is 10% or 15% fetal bovine serum more suitable for raising MSCs?

My routine is to use 15% for the first 3 days of primary culture, then switch to 10% after the cells have basically stabilized adherence and are passaged, and maintain 10% for the long term thereafter. For T75, prepare 50 ml complete medium per batch; 10% means 5 ml serum, and 15% means 7.5 ml. The difference is not large, but it affects MSC morphology. Do not reduce the serum right from the start; perform at least two passages for lot screening. Under the same fetal bovine serum lot, the concentration can also affect the subsequent osteogenic and adipogenic induction status, so it is best to keep it fixed at 10% before differentiation. Low serum is not simply a matter of reducing the concentration; it usually needs to be combined with growth factors or platelet lysate, otherwise slowed proliferation and elongated cell bodies are likely to occur.

It depends on the MSC source. Umbilical cord- and adipose-derived MSCs differ in their sensitivity to serum concentration. Most umbilical cord-derived MSCs can be maintained at 10%, while adipose-derived MSCs are more stable at 15% during the primary adherence stage. For bone marrow MSCs, 10% is usually sufficient, whereas 15% may instead increase the risk of spontaneous differentiation. When preparing 50 ml per T75 flask, it is recommended to use a pipette to add serum accurately rather than estimating based on the markings on the bottle. If the cells proliferate rapidly and maintain stable morphology after passaging, you can first try 7.5%-10%, reducing the concentration each time and observing for 3 passages. Regarding South American fetal bovine serum, lead times have recently not been very stable. With a budget of 5000, it is recommended to focus on in-stock lots and MSC validation data rather than chasing only the lowest price.

10% and 15% are not fixed answers. It is recommended to perform a gradient experiment with the same batch of serum: set two groups at 10% and 15% for primary culture, then reduce both to 10% after passaging to P1, and observe the 72-hour doubling time and morphological changes. If 15% gives better primary attachment, but after P1 the cells become larger and age faster, then use 15% for the first 3 days and switch to 10% after passaging. For low-serum culture, it is best to use a transitional approach, such as gradually reducing 10% complete medium combined with serum replacement, and do not jump directly to 2%-5%. For procurement, with a budget of 5000, focus first on in-stock items from legitimate channels, ask clearly about the certificate of origin, COA, and MSC culture validation records, and keep 2-3 bottles as safety stock.