Countermeasures for Preventing and Treating Opioid Overdose.

The only medication available currently to prevent and treat opioid overdose (naloxone) was approved by the US Food and Drug Administration (FDA) nearly 50 years ago. Because of its pharmacokinetic and pharmacodynamic properties, naloxone has limited utility under some conditions and would not be effective to counteract mass casualties involving large-scale deployment of weaponized synthetic opioids. To address shortcomings of current medical countermeasures for opioid toxicity, a trans-agency scientific meeting was convened by the US National Institute of Allergy and Infectious Diseases/National Institutes of Health (NIAID/NIH) on August 6 and 7, 2019, to explore emerging alternative approaches for treating opioid overdose in the event of weaponization of synthetic opioids. The meeting was initiated by the Chemical Countermeasures Research Program (CCRP), was organized by NIAID, and was a collaboration with the National Institute on Drug Abuse/NIH (NIDA/NIH), the FDA, the Defense Threat Reduction Agency (DTRA), and the Biomedical Advanced Research and Development Authority (BARDA). This paper provides an overview of several presentations at that meeting that discussed emerging new approaches for treating opioid overdose, including the following: (1) intranasal nalmefene, a competitive, reversible opioid receptor antagonist with a longer duration of action than naloxone; (2) methocinnamox, a novel opioid receptor antagonist; (3) covalent naloxone nanoparticles; (4) serotonin (5-HT)1A receptor agonists; (5) fentanyl-binding cyclodextrin scaffolds; (6) detoxifying biomimetic "nanosponge" decoy receptors; and (7) antibody-based strategies. These approaches could also be applied to treat opioid use disorder.

Prospects of embryonic stem cells in treatment of hematopoietic disorders.

Cellular therapies derived from embryonic stem (ES) cells have gained a renewed interest with the experimental demonstration that an embryonic stem cell lines can be established from human blastocyst-stage embryos and prompted to differentiate into almost all types of cells present in the body including hematopoietic cells. Hematopoiesis is a series of cellular processes whereby short-lived mature blood cells are continuously replenished from a pool of rare pluripotential hematopoietic stem cells, in a highly orchestrated process. Aberrances in this intricate process may lead to a malignancy of essential blood-forming organs, causing diseases such as leukemia, aplastic anemia, lymphoma, myelodysplasia and myeloproliferative disorders. Embryonic stem cells show great potential and it may be technologically feasible to transplant differentiated ES cells and to cure various kinds of blood disorders. Understanding the biology of ES cell derived hematopoiesis may lead to the development of co-transplantation protocols that will result in a decreased morbidity and mortality by providing safer and simpler transplantation procedures for patients with malignant and non-malignant conditions. The potential utility of ES cells for gene therapy, tissue engineering and the treatment of a wide variety of currently untreatable diseases is simply too essential to ignore, however, our knowledge and ability to deliver these forms of therapy in a safe and efficient manner requires additional advances in the understanding of the basic biology of ES cells. In this article, we will discuss the factors and methodologies responsible for the differentiation of ES cells into hematopoietic progenitors and their potential to treat different blood related diseases.

Thrombopoietin enhances generation of CD34+ cells from human embryonic stem cells.

The role of thrombopoietin (TPO) in adult hematopoiesis is well-established. A recent report suggests that TPO and vascular endothelial growth factor (VEGF) play a role in promoting formation of early erythropoietic progenitors in a nonhuman primate embryonic stem cell (ES) model. No such report exists for human ES cells as yet. Because TPO may become an important factor promoting human ES cell-derived hematopoiesis, we sought to investigate whether TPO in combination with VEGF can enhance human ES-derived hematopoiesis in an EB-derived culture system. The emphasis of this work was to demonstrate the molecular mechanisms involved in this process, specifically the role of c-mpl and its ligand TPO. Human ES cells were cultured to the EB state, and EB-derived secondary cultures supporting hematopoietic differentiation were established: condition 1, control (stem cell factor [SCF] and Flt3 ligand [Flt3L]); condition 2, SCF, Flt3L, and TPO; and condition 3, SCF, Flt3L, TPO, and VEGF. Cells were harvested daily, starting at day 2 and continuing until day 8, for reverse transcription-polymerase chain reaction and Western blot. There was no evidence of expression of c-mpl and VEGF receptor on the gene or protein level until day 8, when the formation of well-established hematopoietic colonies began. This correlated with the formation of CD34+/CD31- negative progenitors, mostly found in blast-forming units-erythroid-like colonies. We concluded that TPO and VEGF play an important synergistic role in the formation of early ES-derived hematopoietic progenitors that occurs through the c-mpl and VEGF receptors. Disclosure of potential conflicts of interest is found at the end of this article.