In vitro and in vivo evaluation of possible pro-survival activities of PGE2, EGF, TPO and FLT3L on human hematopoiesis

Engineered hematopoietic and immune cells derived from human pluripotent stem cells

For the past decade, significant advances have been achieved in human hematopoietic stem cell (HSC) transplantation for treating various blood diseases and cancers. However, challenges remain with the quality control, amount, and cost of HSCs and HSC-derived immune cells. The advent of human pluripotent stem cells (hPSCs) may transform HSC transplantation and cancer immunotherapy by providing a cost-effective and scalable cell source for fundamental studies and translational applications. In this review, we discuss the current developments in the field of stem cell engineering for hematopoietic stem and progenitor cell (HSPC) differentiation and further differentiation of HSPCs into functional immune cells. The key advances in stem cell engineering include the generation of HSPCs from hPSCs, genetic modification of hPSCs, and hPSC-derived HSPCs for improved function, further differentiation of HPSCs into functional immune cells, and applications of cell culture platforms for hematopoietic cell manufacturing. Current challenges impeding the translation of hPSC-HSPCs and immune cells as well as further directions to address these challenges are also discussed.

No time to die? Intrinsic apoptosis signaling in hematopoietic stem and progenitor cells and therapeutic implications

PURPOSE OF REVIEW

Dysregulated apoptosis contributes to the pathogenesis of many hematologic malignancies. BH3-mimetics, antagonists of antiapoptotic BCL-2 proteins, represent novel, and promising cancer drugs. While the acute myelosuppressive effects of Venetoclax, the first Food and Drug Administration approved BCL-2 inhibitor, are fairly well described, little is known about side effects of novel BH3-mimetics and effects of chronic Venetoclax treatment.

RECENT FINDINGS

Highly relevant publications focused on the effects of acute and chronic Venetoclax therapy, with focus on cell-type specific adaptive mechanisms, the emergence of clonal hematopoiesis, and the selection of BAX-mutated hematopoietic cells in patients treated with Venetoclax for a long period. Important advances were made in understanding primary and secondary Venetoclax resistance and prediction of Venetoclax response. Combination therapies of BH3-mimetics targeting different BCL-2 proteins are highly anticipated. However, human stem and progenitors require both MCL-1 and BCL-XL for survival, and serious myelosuppressive effects of combined MCL-1/BCL-XL inhibition can be expected.

SUMMARY

Long-term studies are indispensable to profile the chronic side effects of Venetoclax and novel BH3-mimetics and better balance their risk vs. benefit in cancer therapy. Combination therapies will be powerful, but potentially limited by severe myelosuppression. For precision medicine, a better knowledge of BCL-2 proteins in the healthy and diseased hematopoietic system is required.

A Retrospective Trial Exploring Erzhu Yiren Decoction in Gastric Ulcer with Spleen Deficiency and Dampness-Heat

Objective

To assess the efficacy of Erzhu Yiren Decoction in treating gastric ulcer of spleen deficiency and dampness-heat and its effect on serum NO, EGF, and PGE2 levels.

Methods

A retrospective study was conducted among 64 patients with gastric ulcers of spleen deficiency and dampness heat admitted to our hospital from September 2019 to May 2020, and they were divided at a ratio of 1 : 1 into an observation group (rabeprazole sodium enteric-coated capsules plus Erzhu Yiren Decoction) and a control group (rabeprazole sodium enteric-coated capsules) based on different treatment methods. The clinical symptom scores, the effective rate of ulcer healing under gastroscopy, the quality of ulcer healing (QOUH), serum nitric oxide (NO), endothelial growth factor (EGF), and prostaglandin E2 (PGE2) levels were compared between the two groups.

Results

The clinical symptom scores of the observation group after treatment were significantly lower than those of the control group (P < 0.001). The observation group obtained a remarkably higher efficacy of ulcer healing under gastroscopy than the control group (P = 0.039). The observation group outperformed the control group in terms of the number of patients with excellent and good QOUH (P = 0.003, 0.014), but no statistical difference in the number of patients with poor QOUH between the two groups was found (P > 0.05). Serum NO, EGF, and PGE2 levels of the observation group after treatment were significantly better than those of the control group (P < 0.001).

Conclusion

Erzhu Yiren Decoction can relieve the clinical symptoms of patients with gastric ulcers of spleen deficiency and dampness heat; improve the serum NO, EGF, and PGE2 levels; optimize the mucosal maturity; and enhance the overall efficacy, which merits clinical promotion.

FLT3 ligand in acute myeloid leukemia: a simple test with deep implications

In contrast to Fms-like tyrosine kinase 3 (FLT3), the influence of FLT3 ligand (FLT3L) on acute myeloid leukemia (AML) biology and disease prognosis has been poorly described. Here we provide an overview of the role played by FLT3L in AML. While being a cytokine implicated in the regulation of hematopoiesis, both in normal situation and after intensive chemotherapy, FLT3L has also a role in enhancing proliferation, inhibiting apoptosis and conferring resistance to FLT3 inhibitors in AML. Moreover, recent independent data show how its measurement may be helpful in the disease management. Indeed, FLT3L could provide a low cost, rapid and noninvasive assessment of chemosensitivity and blast clearance that has robust prognostic significance for patients with AML.

BCL-XL expression is essential for human erythropoiesis and engraftment of hematopoietic stem cells

The anti-apoptotic BCL-2 proteins (BCL-2, BCL-XL, MCL-1, A1, BCL-W) counteract apoptotic signals emerging during development and under stress conditions, and are thus essential for the survival of every cell. While the “BCL-2 addiction” of different cell types is well described in mouse models, there is only limited information available on the role of different anti-apoptotic BCL-2 proteins in a given human cell type. Here we characterize the role of BCL-XL for survival and function of human hematopoietic cells, with the aim to predict hematological side effects of novel BCL-XL-inhibiting BH3-mimetics and to identify hematological malignancies potentially responsive to such inhibitors. Earlier clinical studies have shown that the combined BCL-2/BCL-XL/BCL-W inhibitor, Navitoclax (ABT-263) induces severe thrombocytopenia caused by direct platelet demise and counteracted by increased megakaryopoiesis. In contrast, murine studies have reported important contribution of BCL-XL to survival of late erythroid cells and megakaryocytes. Using lentiviral knockdown, we show that the roles of BCL-XL for human hematopoietic cells are much more pronounced than expected from murine data and clinical trials. Efficient genetic or chemical BCL-XL inhibition resulted in significant loss of human erythroid cells beginning from very early stages of erythropoiesis, and in a reduction of megakaryocytes. Most importantly, BCL-XL deficient human hematopoietic stem cells and multipotent progenitors were reduced in numbers, and they showed a severely impaired capacity to engraft in mice during xenotransplantation. BCL-XL deficiency was fully compensated by BCL-2 overexpression, however, loss of its antagonist BIM did not result in any rescue of human erythroid or stem and progenitor cells. We thus conclude that novel and specific BCL-XL inhibitors might be efficient to treat malignancies of erythroid or megakaryocytic origin, such as polycythemia vera, acute erythroid leukemia, essential thrombocytosis or acute megakaryocytic leukemia. At the same time, it can be expected that they will have more severe hematological side effects than Navitoclax.

FLT3L and granulocyte macrophage colony-stimulating factor enhance the anti-tumor and immune effects of an HPV16 E6/E7 vaccine

HPV16 infections promote the development and progression of cervical cancer. We investigated Fms-like Tyrosine Kinase 3 Ligand and granulocyte macrophage colony-stimulating factor as new adjuvants to an HPV16 vaccine. C57BL/6 mice were immunized by intramuscular injections of HPV16 E6/E7 plasmids every two weeks, three times in all. An in vivo imaging system was used to observe tumor growth and metastasis. Pathological changes to the heart, liver, spleen, lungs, brain and kidneys were recorded, and the survival rate of the mice was determined. The constructed HPV16 E6/E7 vaccine had no notable side effects in terms of physiological or biochemical indexes. Fms-like Tyrosine Kinase 3 Ligand and granulocyte macrophage colony-stimulating factor increased the inhibitory effects of the HPV16 E6/E7 vaccine on tumor growth and metastasis in vivo. The HPV16 E6/E7 vaccine enhanced the survival of mice and increased their serum-specific antibody and interferon-γ levels. Fms-like Tyrosine Kinase 3 Ligand and granulocyte macrophage colony-stimulating factor augmented these effects. In a cytotoxic lymphocyte killing test, Fms-like Tyrosine Kinase 3 Ligand and granulocyte macrophage colony-stimulating factor improved the ability of splenic lymphocytes from HPV16 E6/E7-vaccinated mice to kill B16 cells. As Fms-like Tyrosine Kinase 3 Ligand and granulocyte macrophage colony-stimulating factor enhanced the anti-tumor and immune effects of the HPV16 vaccine, these adjuvants should be considered for the treatment of cervical cancer.