FBS is the default serum supplement in cell culture — used in over 70% of mammalian cell culture protocols worldwide. For many applications it performs well. For others, particularly human cell culture, cell therapy, and ATMP manufacturing, FBS introduces avoidable risks and regulatory complications. This guide explains the key differences, the regulatory context, and the practical decision criteria for choosing between FBS and human serum.
| Parameter | FBS | Human Serum (Type AB Male OTC) |
|---|
| Species origin | Bovine — fetal calf | ✅ Human — matched to cultured cell species |
| Xenogenic antigens | ❌ Present — bovine proteins trigger anti-bovine immune responses in human cells | ✅ None — no xenogenic components |
| EMA/410/01 (ATMPs) | ⚠️ Use discouraged — risk of xenogenic agents, zoonoses | ✅ Preferred ancillary material |
| CAR-T / NK cell expansion | ⚠️ Suboptimal — bovine antigen sensitisation in T cells | ✅ Gold standard — AB Male OTC is the industry reference |
| MSC expansion | Used historically, but ATMP regulations increasingly restrict | ✅ Human Serum AB OTC or hPL — preferred xeno-free options |
| Blood group antibodies | N/A — not applicable to bovine serum | Type AB: none ✅ — universal donor, no anti-A/B cell lysis |
| TRALI risk from female donors | N/A | Male donors only: none ✅ |
| Native growth factor content (OTC) | High — PDGF, EGF, IGF-1 from bovine platelets | ✅ High — PDGF, EGF, TGF-β, IGF-1 from human platelet degranulation (OTC) |
| Lot-to-lot variability | High — major challenge in cell therapy scale-up | High — but male-only donors reduce hormonal variability |
| Cost | ✅ Lower — widely available at competitive price | Higher — limited donor pool, collection costs |
| Regulatory path (Phase I/II) | ⚠️ Requires justification in ATMP dossier | ✅ Preferred — cleaner regulatory path |
| Serum-free alternative | Replace with HSA or recombinant supplements | Replace with HSA, rHSA, or hPL for xeno-free defined media |
| Application | FBS is Appropriate |
|---|
| Standard immortalised cell lines (HeLa, CHO, HEK293, Vero) | No regulatory requirement for human serum. FBS well-validated and cost-effective. |
| Research not involving human cell products | No xenogenic risk concern — FBS performance is validated for these systems. |
| Hybridoma / mAb production (non-ATMP) | Regulatory path established with FBS. Switch to Ultra Low IgG grade if IgG interference is an issue. |
| Protein expression in CHO/HEK293 (non-clinical) | FBS appropriate — switch to serum-free or human serum only if required by downstream regulatory strategy. |
| Application | Human Serum Grade | Reason to Switch |
|---|
| CAR-T cell ex vivo expansion | AB Male Off-the-Clot | EMA/410/01, GMP cell therapy — bovine antigen sensitisation risk in clinical product |
| NK cell expansion | AB Male Off-the-Clot | Xeno-free requirement for ATMP manufacturing |
| MSC expansion for clinical use | AB Male OTC or hPL | EMA/410/01 — phase I/II ATMP dossier |
| Primary human immune cell culture | Heat Inactivated Human Serum | Species match — no bovine antigens activating human immune cells non-specifically |
| Plasmodium falciparum culture | AB OTC | Standard protocol requires AB human serum — blood group specificity and growth factors |
Cells adapted to FBS require a step-wise transition to avoid osmotic shock and growth disruption. A validated protocol:
