What is the main function of fetal bovine serum for cell culture? Is there a significant difference between different batches?

Annual usage is 20-30 bottles of 500 mL. It is recommended to sign a locked-batch agreement through an agent, obtain the same lot number in one order, or have the agent reserve sufficient stock of the same lot number. After arrival, QC should at least include: sterile filtration validation, endotoxin, hemoglobin, and mycoplasma testing, and use your fibroblasts for adherence rate, doubling time, and morphological stability testing. Regarding lead time, imported in-stock items generally take 1-2 weeks, overseas transfers take 3-5 weeks, and lead times exceeding 6 weeks should be treated with caution; domestic agents usually keep stock available and can ship within about 1 week. Within budget, do not focus only on brand; prioritize suppliers that can provide retained samples from the same lot, complete QC certificates, and allow small-sample testing before batch changes.

Serum is not a single component in fibroblast culture; it mainly provides attachment factors (fibronectin, vitronectin, etc.), proliferation-related growth factors (PDGF, FGF, etc.), and lipids/trace elements. Functional assessment should not rely solely on viability. It is recommended to perform three tests for each lot: attachment rate at 6-12 hours after seeding, doubling time or colony formation rate at 48-72 hours, and morphology and viability over 3 consecutive passages. Primary fibroblasts are highly sensitive to lot-to-lot variation; after selecting a lot number, reserve at least six months to one year's supply. The large differences between domestic and South American lots are usually related to elevated endotoxin and hemoglobin. It is recommended to first reduce endotoxin to below 10 EU/mL and hemoglobin to below 20 mg/dL, then evaluate the growth curve.

It doesn't necessarily have to be Australian. Primary fibroblasts have source requirements, but Australian, South American, and domestic sources are more about differences in origin management and do not guarantee that every batch is superior. My approach is to first request 3-5 batch quality inspection certificates and BSE/TSE statements from the supplier, prioritizing batches with low endotoxin and hemoglobin, pH between 7.2-7.6, and clear color. If South American or domestic sources can maintain cell proliferation without decline for three consecutive batches, there is no need to switch to Australian; if the current batch has already affected experimental stability, you can use an Australian batch for parallel comparison before deciding. The biggest taboo when changing sources is switching everything at once; it is recommended to first order 2-3 bottles as a trial batch.