Natural killer cells - new understanding of basic biology may lead to more effective allogeneic haematopoietic stem cell transplantation

MICB Genetic Variants and Its Protein Soluble Level Are Associated with the Risk of Chronic GvHD and CMV Infection after Allogeneic HSCT

The aim of the present study was to determine the associations between the MICB genetic variability and the expression and the risk of development of post-transplant complications after allogeneic hematopoietic stem cell transplantation (HSCT). HSCT recipients and their donors were genotyped for two MICB polymorphisms (rs1065075, rs3828903). Moreover, the expression of a soluble form of MICB was determined in the recipients' serum samples after transplantation using the Luminex assay. Our results revealed a favorable role of the MICB rs1065075 G allele. Recipients with donors carrying this genetic variant were less prone to developing chronic graft-versus-host disease (cGvHD) when compared to recipients without any symptoms of this disease (41.41% vs. 65.38%, p = 0.046). Moreover, the MICB rs1065075 G allele was associated with a lower incidence of cytomegalovirus (CMV) reactivation, both as a donor (p = 0.015) and as a recipient allele (p = 0.039). The MICB rs1065075 G variant was also found to be associated with decreased serum soluble MICB (sMICB) levels, whereas serum sMICB levels were significantly higher in recipients diagnosed with CMV infection (p = 0.0386) and cGvHD (p = 0.0008) compared to recipients without those complications. A protective role of the G allele was also observed for the rs3828903 polymorphism, as it was more frequently detected among donors of recipients without cGvHD (89.90% vs. 69.23%; p = 0.013). MICB genetic variants, as well as serum levels of sMICB, may serve as prognostic factors for the risk of developing cGvHD and CMV infection after allogeneic HSCT.

Reprogram or reboot: small molecule approaches for the production of induced pluripotent stem cells and direct cell reprogramming

Stem cell transplantation is a potential therapy for regenerative medicine, which aims to restore tissues damaged by trauma, aging, and diseases. Since its conception in the late 1990s, chemical biology has provided powerful and diverse small molecule tools for modulating stem cell function. Embryonic stem cells could be an ideal source for transplantation, but ethical concerns restrict their development for cell therapy. The seminal advance of induced pluripotent stem cell (iPSC) technology provided an attractive alternative to human embryonic stem cells. However, iPSCs are not yet considered an ideal stem cell source, due to limitations associated with the reprogramming process and their potential tumorigenic behavior. This is an area of research where chemical biology has made a significant contribution to facilitate the efficient production of high quality iPSCs and elucidate the biological mechanisms governing their phenotype. In this review, we summarize these advances and discuss the latest progress in developing small molecule modulators. Moreover, we also review a new trend in stem cell research, which is the direct reprogramming of readily accessible cell types into clinically useful cells, such as neurons and cardiac cells. This is a research area where chemical biology is making a pivotal contribution and illustrates the many advantages of using small molecules in stem cell research.

Novel strategies for immunotherapy in multiple myeloma: previous experience and future directions

Multiple myeloma (MM) is a life-threatening haematological malignancy for which standard therapy is inadequate. Autologous stem cell transplantation is a relatively effective treatment, but residual malignant sites may cause relapse. Allogeneic transplantation may result in durable responses due to antitumour immunity mediated by donor lymphocytes. However, morbidity and mortality related to graft-versus-host disease remain a challenge. Recent advances in understanding the interaction between the immune system of the patient and the malignant cells are influencing the design of clinically more efficient study protocols for MM. Cellular immunotherapy using specific antigen-presenting cells (APCs), to overcome aspects of immune incompetence in MM patients, has received great attention, and numerous clinical trials have evaluated the potential for dendritic cell (DC) vaccines as a novel immunotherapeutic approach. This paper will summarize the data investigating aspects of immunity concerning MM, immunotherapy for patients with MM, and strategies, on the way, to target the plasma cell more selectively. We also include the MM antigens and their specific antibodies that are of potential use for MM humoral immunotherapy, because they have demonstrated the most promising preclinical results.

Tumor-primed natural killer cells from patients with multiple myeloma lyse autologous, NK-resistant, bone marrow-derived malignant plasma cells

Natural killer (NK) cells are cytotoxic lymphocytes able to kill tumor cells and virus-infected cells. Human-resting NK cells can be activated by co-culture with NK-resistant CTV-1a cells. These tumor-activated cells (TaNKs) are cytotoxic to a range of NK-resistant tumor cells in vitro. This potential, however, has not been explored in multiple myeloma (MM). In this study, we demonstrate that TaNK cells from 21 MM patients lyse a variety of myeloma targets, including primary isolates of autologous and allogeneic CD138+ myeloma cells whilst sparing CD138-ve bone marrow cells. Myeloma patients' TaNK-induced lysis of the U266 cell line was significantly higher compared to normal controls (median-specific lysis 79.1% vs. 69.5%) (P = 0.003). In addition, TaNKs induced substantial lysis of autologous and allogeneic CD138+ myeloma cells (median-specific lysis 52.5% and 37.4%, respectively). The percentage of specific lysis did not correlate with important disease characteristics (ISS, age, and high-risk molecular abnormalities) or with the disease status and antimyeloma treatment, including novel agents and dexamethasone. In conclusion, tumor-primed NK cells are able to induce substantial lysis of myeloma targets including autologous and allogeneic CD138+ myeloma plasma cells and could be an additional therapeutic approach in MM, particularly in the era of novel agents.