There is an emerging field of application for human platelet concentrates as they are rich in growth factors for in vitro culture of various cell types. To this end, the platelets are lysed to release the growth factors to the culture medium, for example by freeze–thaw procedures or by ultrasonic treatment. This human platelet lysate (HPL) is advantageous as compared to the traditionally used foetal bovine serum (FBS): it is xenogen-free – and hence suitable for generation of therapeutic products – and it further increases proliferation rates of cells in culture. On the other hand, neither HPL nor FBS are precisely defined, and there is notorious batch-to-batch variation. Further research is required to unravel the relevant compounds to generate fully defined synthetic culture media – until then, HPL provides a suitable and reliable cell culture supplement particularly in cellular therapy.