Experiments with cultured mammalian cells represent a common in vitro alternative to animal experiments. Fetal calf serum (FCS) is the most commonly used medium supplement. FCS contains a mixture of largely undefined growth factors and cytokines. Since FCS is received from unborn calves older than three months, it represents a massive burden for the pregnant cows and their fetuses. A needle is inserted into the heart of the fetus to collect blood. Since the animal is not under anesthesia, it may suffer pain and discomfort. Furthermore, the undefined nature of FCS is a source of experimental variation, undesired immune responses, and possible contaminations. Thus, alternative, defined, valid, and reliable medium supplements should be identified. We follow the principles of the 3Rs (Replacement, Reduction, Refinement). We established a method to receive human platelet lysate (hPL) from human blood platelets. We investigated if hPL represents potential true alternative for FCS in cell culture experiments and thereby the cruel slaughtering of unborn fetuses. hPL is received by freeze and thawing cycles and centrifugation steps. We successfully adapted three human leukemia cell lines (K562, NB4 and MV4-11) and HCT116 colon cancer cells to culture medium containing 1-5% hPL. We analyzed cell morphology by microscopy. Cell growth kinetics were examined by counting and cell cycle distributions were investigated by flow cytometry. Protein expression patterns were determined globally by global scale proteomics. We additionally determined possible FCS- or hPL-dependent reactions of cells to the well-established anti-cancer drugs Irinotecan, Hydroxyurea and Imatinib, and to epigenetic modulators of the HDAC inhibitor family (FK228 and the new, highly selective HDAC6 inhibitor Marbostat-100) by flow cytometry and Western blot. In these tests, we particularly focused on the expression of the pan-leukemic marker and transcription factor Wilms tumor 1 (WT1) and on the tumor suppressor p53. All tested cell lines grow with 5% FCS and 5% hPL. Cell morphology, cell cycle distribution, and protein expression patterns were not affected by such different culture conditions in resting and treated cells. We further show that the class I HDACs HDAC1-3, but not HDAC6, regulate WT1 and p53. Our findings demonstrate that hPL is a promising replacement for animal serum.

Citation Format: Oliver H. Krämer. Replacing fetal calf serum by human platelet lysate in cancer research and toxicology [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3100.