Abstract
Immune cell therapy has emerged as a promising approach to treat malignancies that were up until recently only treated on a palliative basis. Chimeric antigen receptor- (CAR-) modified T lymphocytes (T cells) in particular have proven to be very effective for certain hematological malignancies. The production of CAR T cells usually involves viral transduction and ex vivo culture of T cells. The aim of this study was to explore the use of human platelet lysate (HPL) compared to two commonly used supplements, human AB serum (ABS) and fetal bovine serum (FBS), for modified T cell production. For studying transduction, activated T cells were transduced with lentivirus to deliver GFP transgenes with three different promoters. Transduction efficiency (percent GFP) was similar among the supplements, and a modest increase in the transgene product (mean fluorescence intensity) was observed when HPL was used as a supplement compared to ABS. To study the effect of supplements on expansion, peripheral blood mononuclear cells (PBMCs) were activated and expanded in the presence of interleukin 2 (IL2) for fourteen days. T cell expansions using HPL and ABS were comparable and slightly less than the expansion obtained with FBS. Interestingly, cells expanded in media supplemented with HPL showed a higher percentage of T cells with a central memory phenotype compared to those expanded in ABS or FBS. Protein profiling revealed that the phenotypic differences may be explained by elevated levels of several cytokines in HPL, including IL7. The results suggest that the use of HPL as a cell culture supplement during the production of modified T cells is a reasonable alternative to ABS. Furthermore, the use of HPL may enhance in vivo performance of the final product by enriching for central memory T cells that are associated with long-term persistence following adoptive transfer.
Highlights
Cellular adoptive immunotherapy with ex vivo-modified T lymphocytes (T cells) has emerged as a promising therapeutic strategy to treat various cancer and autoimmune diseases [1, 2]
We evaluated the efficiency of genetic modification of primary T cells following activation and lentiviral transduction with a CMV-GFP reporter transgene in media containing fetal bovine serum (FBS), AB serum (ABS), or human platelet lysate (HPL)
We observed an increase of transgene levels of GFP+ cells in HPL (2 0 ± 0 3-fold) vs. ABS (0 7 ± 0 2-fold), relative to FBS at day seven (P = 0 0008) (Figure 1(b))
Summary
Cellular adoptive immunotherapy with ex vivo-modified T lymphocytes (T cells) has emerged as a promising therapeutic strategy to treat various cancer and autoimmune diseases [1, 2]. T cells engineered to express chimeric antigen receptors (CARs) have elicited high rates of clinical response against pediatric acute lymphoblastic leukemia, and efforts to target solid tumors are promising and ongoing [3, 4]. The manufacture of CAR T cell therapies typically begins with the collection of mononuclear cells via leukapheresis, followed by genetic modification with viral vectors and ex vivo expansion of the modified cells [5]. The factors determining clinical efficacy of CAR T cell therapy are not entirely understood, the field continues to look for biological features of infused cells that lead to better clinical response. Recent studies have generated a model wherein a balance between CD4+ and CD8+ cells is desirable in immunotherapy transfusion products [7, 10, 11]
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