MEIS inhibitors reduce the viability of primary leukemia cells and Stem cells by inducing apoptosis.

Leukemia stem cells (LSCs) exhibit self-renewal, resistance to standard treatments, and involvement in leukemia relapse. Higher Myeloid Ecotropic Integration Site-1 (MEIS1) expression in leukemic blast samples has been linked to resistance to conventional treatment. We studied the MEIS1 and associated factors in relapsed LSCs and assessed the effect of recently developed MEIS inhibitors (MEISi). Meis1 gene expression was found to be higher in patients with leukemia and relapsed samples. The majority of CD123+ and CD34+ LSCs demonstrated higher MEIS1/2/3 content. Depending on the patient chemotherapy regimen, Meis1 expression increased in relapsed samples. Although there are increased Meis2, Meis3, Hoxa9, Pbx1, or CD34 expressions in the relapsed patients, they are not correlated with Meis1 content in every patient or regimen. MEISi has reduced MEIS1 transcriptional activity and LSC cell survival by apoptosis. Pharmacological targeting with MEISi in LSCs could have a potential effect in limiting leukemia relapse and chemotherapeutic resistance.

Determination of the relationship between CD34+ stem cell amount and DMSO in hematopoetic stem cell transplantation.

It is important to calculate the CD34+ stem cell (SC) count at the right time in patients with hematological malignancies who will undergo Hematopoietic Stem Cell Transplantation (HSCT). The amount of SC infused into the patient affects the engraftment time and healing process of the patient. In this study, we aimed to compare which of the DMSO-not removed and DMSO-removed samples showed the CD34 + SC amount more accurately as the SC amount determination method after the SC was dissolved after cryopreservation in patients who will undergo HSCT. A total of 22 patients were included in the study. All 22 patients were transplanted from frozen samples using DMSO. After the SC products were dissolved in a 37 °C water bath, they were washed 2 times and the amount of CD34+ SC was studied from the samples taken by removing DMSO and without removing DMSO. In the findings, the amounts of CD34+ SC studied with both methods were compared. The increase in the number and percentage of CD34+ SC after DMSO-removed was found to be statistically significant both in terms of difference and proportionally, and the calculated effect sizes also showed that the increase was clinically significant (Cohen's d is between 0.43 and 0.677). After thawing the frozen SCs of the patients who will undergo HSCT, the analysis of CD34+ SCs from which DMSO is removed provides a more accurate calculation of the CD34+ SC amount in the AP.

Patients experienced serious adverse reactions within one hour of hematopoietic stem-cell infusion.

METHODS: SARs were examined occurred within 1 hour after initiating HSC product infusions in all HSCT done in Turkey's Anadolu Medical Center Hospital accredited for HSCTs between 2013 and 2015, targeting 315 patients. RESULTS: SARs were carefully evaluated in this study based on a comparison of the amount of stem cells infused, age, frozen sample (FS) / non-frozen samples (NFS) between HSCs sources. Rate of SARs is significantly higher in FS infusions supports the hypothesis that DMSO plays an important role in the development of SAR. CONCLUSION: The rate of SARs is significantly higher in infusions given using FSs confirms the hypothesis that the preservative agent DMSO plays an important role in the development of SAR. Our study provides guidance for future studies on the necessity of reducing the amount of DMSO in the HSCT product and using other alternative freezing agents instead of DMSO.

The Historical Relationship Between Meis1 and Leukemia.

Acute leukemia (AL) is a poor progressive resistant hematological disease, which has different subtypes and immunophenotypic properties according to leukemic blasts. AL is caused by genetic changes and associated with leukemia stem cells (LSCs), which determine its prognosis and endurance. LSCs are thought to be hematopoietic progenitor and stem cell (HPSCs)-like cells that underwent a malignant transformation. In addition to their low number, LSCs have the characteristics of self-renewal, resistance to chemotherapy, and relapse of leukemia. The myeloid ecotropic integration site-1 (MEIS1) protein is a member of the three-amino acid loop extension (TALE) family of homeodomain (HD) proteins that can bind to DNA sequence-specific manner. Studies have shown that overexpression of MEIS1 and associated cofactors involves tumorigenesis of numerous cancers. Historically, increased expression of Meis1 transcript as well as protein has been determined in acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) patients. Moreover, resistance to conventional chemotherapy was observed in leukemic blast samples with high Meis1 content. In this review article, the molecular mechanism of the oncological role of the MEIS1 protein in leukemia and LSC is discussed. In addition, it was suggested that MEIS1 protein could be utilized as a possible treatment target in leukemia with an emphasis on the inhibition of MEIS1, which is overexpressed in LSC.

Development of Small Molecule MEIS Inhibitors that modulate HSC activity.

Meis1, which belongs to TALE-type class of homeobox gene family, appeared as one of the key regulators of hematopoietic stem cell (HSC) self-renewal and a potential therapeutical target. However, small molecule inhibitors of MEIS1 remained unknown. This led us to develop inhibitors of MEIS1 that could modulate HSC activity. To this end, we have established a library of relevant homeobox family inhibitors and developed a high-throughput in silico screening strategy against homeodomain of MEIS proteins using the AutoDock Vina and PaDEL-ADV platform. We have screened over a million druggable small molecules in silico and selected putative MEIS inhibitors (MEISi) with no predicted cytotoxicity or cardiotoxicity. This was followed by in vitro validation of putative MEIS inhibitors using MEIS dependent luciferase reporter assays and analysis in the ex vivo HSC assays. We have shown that small molecules named MEISi-1 and MEISi-2 significantly inhibit MEIS-luciferase reporters in vitro and induce murine (LSKCD34l°w cells) and human (CD34+, CD133+, and ALDHhi cells) HSC self-renewal ex vivo. In addition, inhibition of MEIS proteins results in downregulation of Meis1 and MEIS1 target gene expression including Hif-1α, Hif-2α and HSC quiescence modulators. MEIS inhibitors are effective in vivo as evident by induced HSC content in the murine bone marrow and downregulation of expression of MEIS target genes. These studies warrant identification of first-in-class MEIS inhibitors as potential pharmaceuticals to be utilized in modulation of HSC activity and bone marrow transplantation studies.

Developments in Artificial Platelet and Erythroid Transfusion Products.

Platelet and blood transfusions have vital importance to the lives of many patients. Platelet transfusions are a life-saving intervention by reducing risk of bleeding in thrombocytopenic patients. Due to the short shelf life of platelets and their limited availability, researchers have developed various platelet transfusion production technologies. Understanding the cellular and biophysical mechanisms of platelet release is particularly important for development of platelet transfusion products (PTPs) and to translate them to clinical applications in patients requiring platelet infusion. Similarly, due to donor dependence and increased clinical need of blood transfusions, studies on the erythroid transfusion products (ETPs) have recently gained momentum. This led to development of ETP technologies involving differentiation of stem cells to fully functional erythrocytes in vitro. During megakaryopoiesis or erythropoiesis, various stimulatory factors, growth factors, transcription factors, and biophysical conditions have been shown to play a crucial role in the formation final blood products. Thus, understanding of the in vivo mechanisms of platelet release and erythrocyte maturation is particularly important for mimicking these conditions in vitro. This review focuses on latest and up-to-date information about the innovations in PTP and ETP technologies. We also discuss some of the recent fundamental findings that have changed our understanding of in vivo platelet release and blood formation. Human bone marrow acts as a source of cells required for erythropoiesis and megakaryopoeiesis. Understanding of molecular mechanism and physiology of these vital and curitial events allowed us to mimic these conditions ex vivo and to develop artificial platelet and erythroid transfusion production technologies.

c-Myc Inhibitor 10074-G5 Induces Murine and Human Hematopoietic Stem and Progenitor Cell Expansion and HDR Modulator Rad51 Expression.

BACKGROUND: c-Myc plays a major role in the maintenance of glycolytic metabolism and hematopoietic stem cell (HSC) quiescence. OBJECTIVE: Targeting modulators of HSC quiescence and metabolism could lead to HSC cell cycle entry with concomitant expansion. METHODS AND RESULTS: Here we show that c-Myc inhibitor 10074-G5 treatment leads to 2-fold increase in murine LSKCD34low HSC compartment post 7 days. In addition, c-Myc inhibition increases CD34+ and CD133+ human HSC number. c-Myc inhibition leads to downregulation of glycolytic and cyclindependent kinase inhibitor (CDKI) gene expression ex vivo and in vivo. In addition, c-Myc inhibition upregulates major HDR modulator Rad51 expression in hematopoietic cells. Besides, c-Myc inhibition does not alter proliferation kinetics of endothelial cells, fibroblasts or adipose-derived mesenchymal stem cells, however, it limits bone marrow derived mesenchymal stem cell proliferation. We further demonstrate that a cocktail of c-Myc inhibitor 10074-G5 along with tauroursodeoxycholic acid (TUDCA) and i-NOS inhibitor L-NIL provides a robust HSC maintenance and expansion ex vivo as evident by induction of all stem cell antigens analyzed. Intriguingly, the cocktail of c-Myc inhibitor 10074-G5, TUDCA and L-NIL improves HDR related gene expression. CONCLUSION: These findings provide tools to improve ex vivo HSC maintenance and expansion, autologous HSC transplantation and gene editing through modulation of HSC glycolytic and HDR pathways.