Human platelet lysate as a media supplement for ex vivo expansion of immune cells

Adoptive immunotherapy with ex vivo-derived T lymphocytes (T cells) and natural killer cells (NK cells) has emerged as a very effective therapeutic strategy to treat various cancer and autoimmune diseases. Adoptive cellular therapy involves the ex vivoexpansion of lymphocytes under cGMP regulations. The use of fetal bovine serum (FBS) as a supplement for cell culture carries a risk of pathogen transmission as well as xenoimmunization against bovine antigens. Human AB serum, yet another cell culture option for T cells and NK cells, has supply limitations and therefore may not be sufficient to meet the expected demand for immunotherapies. Platelet lysate (HPL) obtained from outdated human donor platelets is widely recognized as a valuable, alternative to both FBS and human AB serum for cell culture. This study explores the potential use of HPL to expand T cells and NK cells. Primary human CD3+ and CD56+ cells were isolated from peripheral blood mononuclear cells using negative and positive immunomagnetic separation, respectively. Both T and NK cells were expanded in vitro using basal media supplemented with either FBS, AB serum or HPL with the addition of CD3/CD28 activator plus interleukin-2 for T cells and interleukin-2 plus interleukin-15 for NK cells. The growth kinetics and viability of T cells expanded with the three different media supplements were comparable, whereas higher expansion rate and better viability was observed for NK cells expanded with HPL compared to FBS and AB serum. This study demonstrates the feasibility to use human HPL as a successful alternative to FBS and human AB serum to effectively propagate primary human lymphocytes.