Mesenchymal Stromal Cells from Perinatal Tissues as an Alternative for Ex Vivo Expansion of Hematopoietic Progenitor and Stem Cells from Umbilical Cord Blood.

Umbilical cord blood (UCB) serves as a source of hematopoietic stem and progenitor cells (HSPCs) utilized in the regeneration of hematopoietic and immune systems, forming a crucial part of the treatment for various benign and malignant hematological diseases. UCB has been utilized as an alternative HSPC source to bone marrow (BM). Although the use of UCB has extended transplantation access to many individuals, it still encounters significant challenges in selecting a histocompatible UCB unit with an adequate cell dose for a substantial proportion of adults with malignant hematological diseases. Consequently, recent research has focused on developing ex vivo expansion strategies for UCB HSPCs. Our results demonstrate that co-cultures with the investigated mesenchymal stromal cells (MSCs) enable a 10- to 15-fold increase in the cellular dose of UCB HSPCs while partially regulating the proliferation capacity when compared to HSPCs expanded with early acting cytokines. Furthermore, the secretory profile of UCB-derived MSCs closely resembles that of BM-derived MSCs. Moreover, both co-cultures exhibit alterations in cytokine secretion, which could potentially impact HSPC proliferation during the expansion process. This study underscores the fact that UCB-derived MSCs possess a remarkably similar supportive capacity to BM-derived MSCs, implying their potential use as feeder layers in the ex vivo expansion process of HSPCs.

Ex vivo expansion of regulatory T cells from long-term Belatacept-treated kidney transplant patients restores their phenotype and suppressive function but not their FOXP3 TSDR demethylation status.

We recently reported that Tregs from long-term Belatacept-treated kidney transplant patients displayed an altered phenotype and impaired suppressive function compared to Tregs from healthy controls. However, it remains unknown whether ex vivo expansion of Tregs from patients who underwent long-term immunosuppression may be feasible to be used in their treatment. In this work, Tregs from Belatacept-treated patients were polyclonally expanded in vitro in the presence of rapamycin and IL-2. After four weeks of expansion, Tregs from patients expressed high levels of FOXP3, CD25, CTLA-4, Helios and CCR7, and showed strong suppressive activity, even in the presence of pro-inflammatory cytokines. However, FOXP3 TSDR demethylation remained lower in expanded Tregs from Belatacept-treated patients compared to healthy control Tregs. These data suggest that ex vivo expansion of Tregs from patients undergoing long-term immunosuppression may require the use of epigenetic modifying agents to stabilize FOXP3 expression to be considered as treatment in kidney transplant patients.

Natural killer cell adoptive immunotherapy: Coming of age.

Cell therapy is a promising alternative to harsh chemotherapy and radiation therapy for cancer. Natural killer (NK) cells in particular have great potential for direct use in adoptive immunotherapy (AI) for cancer and to improve the graft-vs-leukemia (GVL) effect of hematopoietic stem cell transplants (HSCTs). NK cell number and function are associated with a strong GVL effect without inducing graft-versus-host disease in most settings. Clinical trials demonstrating the therapeutic role of NK cells in HSCT recipients or testing the safety and efficacy of AI with NK cells have been primarily directed at treating acute myeloid leukemia, although investigators have used NK cells for treatment of other hematological diseases, sarcomas, carcinomas, and brain tumors. Major challenges must be overcome in making NK cell-based therapy cost-effective, the most important being the need to collect or generate an adequate number of effector cells. In this review, we discuss protocols for isolation, expansion, and in vitro propagation of large quantities of functional NK cells that meet the criteria for clinical applications. Among the methods described are the use of bioreactors for scaling up production and expansion of NK cells in the presence of interleukins and feeder cells. We also discuss novel methodologies that optimize the generation of clinical grade NK-cell products for AI.