Functional evaluation of ex vivo expanded cord blood lymphocytes: possible use for adoptive cellular immunotherapy

Efficient lentiviral transduction method to gene modify cord blood CD8+ T cells for cancer therapy applications

Adoptive T cell therapy utilizing tumor-specific autologous T cells has shown promising results for cancer treatment. However, the limited numbers of autologous tumor-associated antigen (TAA)-specific T cells and the functional aberrancies, due to disease progression or treatment, remain factors that may significantly limit the success of the therapy. The use of allogeneic T cells, such as umbilical cord blood (CB) derived, overcomes these issues but requires gene modification to induce a robust and specific anti-tumor effect. CB T cells are readily available in CB banks and show low toxicity, high proliferation rates, and increased anti-leukemic effect upon transfer. However, the combination of anti-tumor gene modification and preservation of advantageous immunological traits of CB T cells represent major challenges for the harmonized production of T cell therapy products. In this manuscript, we optimized a protocol for expansion and lentiviral vector (LV) transduction of CB CD8⁺ T cells, achieving a transduction efficiency up to 83%. Timing of LV treatment, selection of culture media, and the use of different promoters were optimized in the transduction protocol. LentiBOOST was confirmed as a non-toxic transduction enhancer of CB CD8⁺ T cells, with minor effects on the proliferation capacity and cell viability of the T cells. Positively, the use of LentiBOOST does not affect the functionality of the cells, in the context of tumor cell recognition. Finally, CB CD8⁺ T cells were more amenable to LV transduction than peripheral blood (PB) CD8+ T cells and maintained a more naive phenotype. In conclusion, we show an efficient method to genetically modify CB CD8⁺ T cells using LV, which is especially useful for off-the-shelf adoptive cell therapy products for cancer treatment.

Cord blood as a source of non-senescent lymphocytes for tumor immunotherapy

While proof of concept that the immune system can be harnessed to attack cancer cells has been established, only a minority of patients are cured with immunotherapeutic regimens designed to enhance host autologous immunity. Recently acquired knowledge indicates that the low response rates associated with conventional cancer immunotherapy could be attributed, at least in part, to the processes of immunosenescence and replicative senescence, which consequently render the anti-tumor T cell clones of the aged host quantitatively insufficient and qualitatively impaired to elicit an effective anti-cancer response. Therefore, it is anticipated that the efficacy of adoptive T cell cancer immunotherapy can be dramatically improved by utilizing "young" T cells with targeted antigen specificity derived from umbilical cord blood, instead of current practice using autologous senescent T cells derived usually from aged cancer patients. Functionally competent CD8(+) T cells specific against tumor antigens (e.g. Her2/neu and MAGEA3) as well as against viral antigens have been recently generated from cord blood mononuclear cells suggesting that cord blood can be a source of "young" anti-tumor T cells for adoptive cancer immunotherapy. Moreover, cord blood can give rise to antigen non-specific effector cells including NK cells and dendritic cells. Finally, umbilical cord blood anti-tumor specific T cell clones are unlikely to have participated in tumor immunoediting, making them more efficient than host T cells in eradicating tumor cells.

Clinical expansion of cord blood-derived T cells for use as donor lymphocyte infusion after cord blood transplantation

Allogeneic stem cell transplantation (SCT) from cord blood (CB) as a stem cell source is a promising alternative when no human leukocyte antigen-matched donor is found. Donor lymphocyte infusion (DLI) is a possible treatment modality for threatening graft failure or relapse of an underlying malignancy after transplantation. Ethical and logistical reasons limit the possibility of DLI in the setting of CB SCT. To remedy this restriction, we performed expansion of donor T cells in vitro from CB grafts in a clinical setting for use as future DLI and characterized the expanded cells in comparison to T cells from CB acquired ex vivo and adult peripheral blood. T cells were expanded from grafts used for transplantation, upon CD3/CD28 crosslinking and culture in interleukin-2. Phenotype and function of T cells were assessed by flow cytometry and mixed lymphocyte culture assays. T-cell receptor repertoire distribution was evaluated with polymerase chain reaction-based spectratyping. We were able to amplify T cells to sufficient amounts for DLI in 13 out of 13 initiated expansions. Expanded T cells presented with an activated phenotype and could be induced to produce cytokines by a nonspecific stimulus. When exposed to allogeneic targets, expanded CB T cells proliferated at comparable levels to their ex vivo and adult blood counterparts. In summary, clinical expansion of CB T cells for DLI is feasible and may be a future modality for treatment of graft failure or relapse after SCT.

Ex vivo expanded cord blood CD4 T lymphocytes exhibit a distinct expression profile of cytokine-related genes from those of peripheral blood origin

With an increase in the importance of umbilical cord blood (CB) as an alternative source of haematopoietic progenitors for allogenic transplantation, donor lymphocyte infusion (DLI) with donor CB-derived activated CD4(+) T cells in the unrelated CB transplantation setting is expected to be of increased usefulness as a direct approach for improving post-transplant immune function. To clarify the characteristics of activated CD4(+) T cells derived from CB, we investigated their mRNA expression profiles and compared them with those of peripheral blood (PB)-derived activated CD4(+) T cells. Based on the results of a DNA microarray analysis and quantitative real-time reverse transcriptase-polymerase chain reaction (RT-PCR), a relatively high level of forkhead box protein 3 (Foxp3) gene expression and a relatively low level of interleukin (IL)-17 gene expression were revealed to be significant features of the gene expression profile of CB-derived activated CD4(+) T cells. Flow cytometric analysis further revealed protein expression of Foxp3 in a portion of CB-derived activated CD4(+) T cells. The low level of retinoic acid receptor-related orphan receptor gamma isoform t (RORgamma t) gene expression in CB-derived activated CD4(+) T cells was speculated to be responsible for the low level of IL-17 gene expression. Our data indicate a difference in gene expression between CD4(+) T cells from CB and those from PB. The findings of Foxp3 expression, a characteristic of regulatory T cells, and a low level of IL-17 gene expression suggest that CB-derived CD4(+) T cells may be a more appropriate source for DLI.

Characterization of natural killer and natural killer-like T cells derived from ex vivo expanded and activated cord blood mononuclear cells: implications for adoptive cellular immunotherapy

OBJECTIVE

Cord blood (CB) is limited by the absence of available donor effector cells for post-unrelated CB transplantation adoptive cellular immunotherapy. We reported the ability to ex vivo expand (EvE) CB mononuclear cells (MNC) after short-term incubation with anti-CD3, interleukin (IL)-2, IL-7, and IL-12 (antibody/cytokine [AB/CY]) into subpopulations of CD3(-)/56(+) natural killer (NK) cells with enhanced in vitro and in vivo tumor cytotoxicity.

MATERIALS AND METHODS

We compared 2- vs 7-day EvE of rethawed CB MNCs in AB/CY and activation of NK and NK-like T (NKT) cell (CD3(+)/56(+)) subsets expressing specific NK-cell receptors along with IL-15, IL-18, and interferon-gamma production.

RESULTS

Nonadherent total cell number were significantly increased at day 7 (p<0.001) along with NK-cell number (20-fold) and an enrichment in NKT-like subsets (36-fold). There was no change in the NK(dim) subset; yet the NKT(bright) and NKT KIR3DL1(dim) subsets were significantly increased (p<0.05). NK cells expressing the inhibitory natural cytoxicity receptor CD94/NKG2A were decreased (p<0.001), while those expressing activating natural cytoxicity receptor CD94/NKG2D receptor and activating NK and NKT KIR2DS4 subsets were significantly increased (p<0.001). IL-18 and interferon-gamma protein production was also significantly increased (p<0.001 and p<0.05, respectively). Lysosomal-associated membrane protein-1 and granzyme B expression were increased (p<0.001 and p>0.01, respectively), which correlated with the significant increase in NK, LAK, and tumor cytotoxicity of the EvE cells.

CONCLUSION

This study demonstrates that previously cryopreserved and rethawed CB MNCs can be EvE up to 7 days to yield viable and activated NK and NKT-like subsets that appear to be cytolytic based on the cell repertoire and could be utilized in the future as adoptive cellular immunotherapy post-unrelated CB transplantation.

Differentiation of naive cord-blood T cells into CD19-specific cytolytic effectors for posttransplantation adoptive immunotherapy

Disease relapse is a barrier to achieving therapeutic success after unrelated umbilical cord-blood transplantation (UCBT) for B-lineage acute lymphoblastic leukemia (B-ALL). While adoptive transfer of donor-derived tumor-specific T cells is a conceptually attractive approach to eliminating residual disease after allogeneic hematopoietic stem cell transplantation, adoptive immunotherapy after UCBT is constrained by the difficulty of generating antigen-specific T cells from functionally naive umbilical cord-blood (UCB)-derived T cells. Therefore, to generate T cells that recognize B-ALL, we have developed a chimeric immunoreceptor to redirect the specificity of T cells for CD19, a B-lineage antigen, and expressed this transgene in UCB-derived T cells. An ex vivo process, which is compliant with current good manufacturing practice for T-cell trials, has been developed to genetically modify and numerically expand UCB-derived T cells into CD19-specific effector cells. These are capable of CD19-restricted cytokine production and cytolysis in vitro, as well as mediating regression of CD19+ tumor and being selectively eliminated in vivo. Moreover, time-lapse microscopy of the genetically modified T-cell clones revealed an ability to lyse CD19+ tumor cells specifically and repetitively. These data provide the rationale for infusing UCB-derived CD19-specific T cells after UCBT to reduce the incidence of CD19+ B-ALL relapse.

Ex vivo amplification of T cells from human cord blood

The current status of immunotherapy for cancer is here summarized with particular attention to the new methodologies developed for ex vivo expansion of T cells from neonatal cord blood. Umbilical cord blood (UCB) mononuclear cells (MNC) generate CD45RA naive T lymphocytes when cultured under serum-deprived conditions with appropriate combinations of growth factors. These ex vivo generated T cells resemble precursors for the lymphoid lineage present in adult bone marrow in terms of active transcription of RAG-2 and pTalpha.

Ex Vivo Expansion of Human Umbilical Cord Blood-Derived T-Lymphocytes with Homologous Cord Blood Plasma

This study was designed to establish a more effective and safe culture system for adoptive immunotherapy by investigating the use of homologous cord blood plasma (HCBP) instead of fetal bovine serum (FBS), which has various limitations including ethical problems for the ex vivo expansion of human umbilical T lymphocytes. Fresh human umbilical mononuclear cell fractions were isolated by Ficoll-Hypaque density centrifugation. Nonadherent mononuclear cell fractions were cultured with anti-CD3 antibody (5 microg/ml), IL-2 (175 U/ml), and either 10% FBS or 10% HCBP. On day 8, the cellular proliferation rate and cell surface markers were assessed. There was no significant difference in proliferation when human umbilical cord blood T lymphocytes were grown in medium supplemented with FBS or HCBP (p > 0.05). In medium containing FBS, the proportion of CD3(+)CD4(+) (markers for helper T cell), CD3(+)CD8(+) (cytotoxic T cell), CD3(+)CD25(+) (activated T cell), CD3(+)CD38(+) (immature T cell), and CD3(+)CD45RO(+) (memory T cell) cells was significantly increased (p < 0.05), whereas proportion of CD3(+)CD45RA(+) (naive T cell) and CD16(+)CD56(+) (NK cell) cells was significantly decreased (p < 0.05). In HCBP supplemented medium, the proportion of CD3(+)CD8(+), CD3(+)CD25(+), CD3(+)CD45RA(+), and CD3(+)CD45RO(+) cells was significantly increased (p < 0.05). The proportion of CD3(+)CD4(+), CD3(+)CD45RO(+) and CD3(+)CD38(+) cells was significantly higher, but proportion of CD3(+)CD45RA(+) and CD3(+)CD8(+) cells was significantly lower in FBS compared with HCBP supplemented medium (p < 0.05). Our results support the feasibility of ex vivo expansion of human umbilical cord blood T lymphocytes in medium supplemented with HCBP for future adoptive cellular immunotherapy.

Cytotoxic Difference of T Cells Expanded with Anti-CD3 Monoclonal Antibody in the Presence and Absence of Anti-CD28 Monoclonal Antibody

Bulk T cells can be expanded by CD3 stimulation alone (CD3-Ts) or by CD3/CD28 dual stimulation (CD3/CD28-Ts) of peripheral blood mononuclear cells (PBMC). However, few reports have described the difference of features between CD3-Ts and CD3/CD28-Ts. PBMC were stimulated with anti-CD3 monoclonal antibody (mAb) alone or co-stimulated with anti-CD3/CD28 mAbs immobilized on plastic plates, in the presence of rhIL-2 for 4 days, subsequently cultured in the presence of rhIL-2 with no antibody then analyzed. The expansion rate was significantly lower for CD3-Ts (965 + 510-fold, n=5) than CD3/CD28-Ts (2263 + 856-fold, n=5) (p<0.05). The CD4/CD8 ratio, the percentage of CD28(+) cell, and the percentage of T cells with no ability to generate intracytoplasmic interleukin-4 (IL-4) or interferon-gamma (IFN-gamma) were all significantly higher, but, phenotypically, memory cells were lower in CD3/CD28-Ts than in CD3-Ts. The levels of activity of both natural killer (NK) and lymphocyte-activated killer (LAK) cells were lower in CD3/CD28-Ts than CD3-Ts. In comparison to CD3-Ts, CD3/CD28-Ts showed impaired migration toward RANTES. In conclusion, T cells expanded with anti-CD3 and anti-CD28 mAbs differ from those expanded with anti-CD3 alone with proliferation, cytotoxicity, chemotaxis, and phenotype. These differences may exert profound influences on the therapeutic potential of output cells.

Complete resolution of severe chronic active Epstein-Barr virus infection by cultured, activated donor T lymphocyte infusion after nonmyeloablative stem cells allografting

A patient with chronic active Epstein-Barr virus (EBV) infection was treated by allogeneic SCT from an HLA-identical sibling donor, using a nonmyeloablative regimen. Even on day 70, mixed chimerism remained together with a quite high viral load. On days 76 and 90, donor lymphocytes were infused after short-term culture with OKT3 plus recombinant IL-2. At 8 days after the last dose, all hematopoietic cells were shown to be donor-type dominant; thereafter, the viral load started to decrease and finally disappeared. Anti-mHA-specific CTLs were generated in vitro, which were shown to be effective in eradicate viral-infected recipient T lymphocytes.

Amplification of T cells from human cord blood in serum-deprived culture stimulated with stem cell factor, interleukin-7 and interleukin-2

We report the effects exerted by cytokine combinations, including stem cell factor (SCF), interleukin-7, interleukin-4 and interleukin-2, on the amplification of T cells from cord blood (CB) mononuclear cells cultured for 10-11 days under serum-deprived conditions. Of all the combinations investigated, SCF+interleukin-7 sustained the best fold increase (FI) of total nucleated cells (FI=6.4+/-1.17), amplifying preferentially CD4(+) over CD8(+) T-cell subsets (FI=4.72+/-0.79 vs 2.73+/-1.2, respectively, P<0.05). The addition of interleukin-2 to this combination did not significantly increase the total number of cells generated (FI=7.4+/-2.27), but allowed preferential amplification of CD8(+) over CD4(+) T cells (FI=6.04+/-0.14 vs 1.67+/-0.6, respectively, P<0.05). Single-strand conformation polymorphism analysis of the T-cell receptor V(beta)-chain rearrangements expressed by the expanded T cells indicated that the complexity of the T-cell repertoire had increased after 10 days of culture in the presence of SCF and IL-7. Interestingly, a modest expansion (FI=8.67+/-1.5) of myeloid progenitor cells was also observed in these cultures. These results indicate that it is possible to expand specific T-cell subsets for adoptive immunotherapy without losing myeloid progenitor cells necessary for neutrophil recovery after CB transplantation, by modulating the cytokines added to the cultures.