Off-the-clot (OTC) serum is collected while the blood is clotting, capturing the platelet degranulation event that releases growth factors including PDGF, EGF, TGF-β and IGF-1 into the serum. Standard clotted serum is collected after the clot has fully formed and these factors have been partly consumed or lost. The result is a substantially higher and more physiological growth factor content in OTC serum — directly relevant for cell expansion applications where these factors drive proliferation, migration or differentiation.

Cell types that respond to PDGF, EGF, TGF-β or IGF-1 signalling benefit most: mesenchymal stem cells (MSC), fibroblasts, smooth muscle cells and epithelial cells. For these types, OTC serum can support higher expansion rates, improved viability and enhanced differentiation potential compared to standard clotted serum at the same percentage in medium. For cell types not dependent on these growth factor signals — most established continuous lines — standard clotted serum is equally effective and more cost-efficient.

Both are off-the-clot serum with the same native growth factor profile. Human Serum OTC (Mixed) uses a pooled mixed-gender, mixed blood-type donor population — providing maximum lot size and cost-effective pricing. Human Serum OTC Type AB Male applies the same OTC collection format but restricts donors to blood type AB males only, providing blood-type neutrality, no TRALI risk and reduced hormonal variability. Choose OTC Mixed when donor definition is not required; choose OTC Type AB Male for stricter process control or TRALI-sensitive workflows.

Human Serum OTC from SeamlessBio is intended for non-GMP research and process development workflows. For regulated ATMP manufacturing, we provide Ph. Eur. 5.2.12-compliant donor documentation on request, which is a prerequisite for regulatory submissions involving human serum-based process components. If you are developing an ATMP process, we recommend contacting our team early to ensure the right documentation package is in place for your regulatory strategy.

Each batch is supplied with a Certificate of Analysis (CoA). On request, we provide ATMP-relevant donor documentation per Ph. Eur. 5.2.12, heat inactivation or gamma irradiation records, low-endotoxin test certificates and lot reservation agreements. All documents are available in English.

Yes. Heat inactivated (56 °C, 30 min) and gamma irradiated versions are available on request. Note that heat inactivation reduces growth factor activity — particularly for PDGF and EGF — compared to native OTC serum. If complement inactivation is required alongside preserved growth factor content, gamma irradiation is generally preferred. Please discuss your requirements with the SeamlessBio team so we can recommend the right treatment for your application.

Available in standard bottle formats and in bag formats for larger volumes. There is no minimum order quantity. Bulk orders and lot reservations for scale-up or long-running process development programmes can be arranged on request. Contact us for current stock, pricing and lead times.

Yes. SeamlessBio ships Human Serum OTC cold-chain to all EU member states, the United Kingdom and Switzerland. We manage all required export and import documentation. Contact us for current lead times and shipping conditions for your region.