Human Hematopoietic Stem Cells: Concepts and Perspectives on the Biology and Use of Fresh Versus In Vitro–Generated Cells for Therapeutic Applications

Differentiated Cells Derived from Hematopoietic Stem Cells and Their Applications in Translational Medicine

Hematopoietic stem cells (HSCs) and their development are one of the most widely studied model systems in mammals. In adults, HSCs are predominantly found in the bone marrow, from where they maintain homeostasis. Besides bone marrow and mobilized peripheral blood, cord blood is also being used as an alternate allogenic source of transplantable HSCs. HSCs from both autologous and allogenic sources are being applied for the treatment of various conditions like blood cancers, anemia, etc. HSCs can further differentiate to mature blood cells. Differentiation process of HSCs is being extensively studied so as to obtain a large number of pure populations of various differentiated cells in vitro so that they can be taken up for clinical trials. The ability to generate sufficient quantity of clinical-grade specialized blood cells in vitro would take the field of hematology a step ahead in translational medicine.

Ex Vivo Manufacture of Megakaryocytes and Platelets from Stem Cells: Recent Advances Toward Transfusion in Humans

The generation of ex vivo functional megakaryocytes (MK) and platelets is an important issue in transfusion medicine as donor dependence implies in limitations, such as shortage of eligible volunteers. Indeed, platelet transfusion is still a procedure that saves the lives of patients with defective platelet production. Recent technological development has enabled the isolation and expansion of stem cells that can be used as a source for the production of functional platelets for transfusion. In this review, we discuss recent approaches of in vitro or ex vivo production of MK and platelets, suggesting that, in the near future, donor-independent sources may become a possibility. The feasibility of using these cells in the clinic may be safer, and in vitro manipulation could generate universally compatible products, solving problems related to platelet refractoriness. However, functionality and survival testing of these products in human beings are scarce; therefore, additional studies are needed to consolidate this purpose.

Could gene therapy cure HIV?

The Human Immunodeficiency Virus (HIV)/Acquired Immune Deficiency Syndrome (AIDS) continues to be a major global public health issue, having claimed almost 33 million lives so far. According to the recent report of the World Health Organization (WHO) in 2019, about 38 million people are living with AIDS. Hence, finding a solution to overcome this life-threatening virus can save millions of lives. Scientists and medical doctors have prescribed HIV patients with specific drugs for many years. Methods such antiretroviral therapy (ART) or latency-reversing agents (LRAs) have been used for a while to treat HIV patients, however they have some side effects and drawbacks causing their application to be not quite successful. Instead, the application of gene therapy which refers to the utilization of the therapeutic delivery of nucleic acids into a patient's cells as a drug to treat disease has shown promising results to control HIV infection. Therefore, in this review, we will summarize recent advances in gene therapy approach against HIV.

Cancer Biology, Epidemiology, and Treatment in the 21st Century: Current Status and Future Challenges From a Biomedical Perspective

Since the second half of the 20th century, our knowledge about the biology of cancer has made extraordinary progress. Today, we understand cancer at the genomic and epigenomic levels, and we have identified the cell that starts neoplastic transformation and characterized the mechanisms for the invasion of other tissues. This knowledge has allowed novel drugs to be designed that act on specific molecular targets, the immune system to be trained and manipulated to increase its efficiency, and ever more effective therapeutic strategies to be developed. Nevertheless, we are still far from winning the war against cancer, and thus biomedical research in oncology must continue to be a global priority. Likewise, there is a need to reduce unequal access to medical services and improve prevention programs, especially in countries with a low human development index.

Human cord blood hematopoietic cells acquire neural features when cultured in the presence of neurogenic cytokines

In vitro growth of hematopoietic cells depends on the presence of hematopoietic cytokines. To date, it is unclear if these cells would be able to respond to non-hematopoietic cytokines. In the present study, we have explored this by culturing human hematopoietic cells in presence of neurogenic cytokines. Lineage-negative (Lin^-) umbilical cord blood (UCB)-derived cells -enriched for hematopoietic stem and progenitor cells- were cultured in presence of different combinations of hematopoietic cytokines, neurotrophins, epidermal growth factor, fibroblast growth factor, and neurogenic culture media, in a 3-phase culture system. A proportion (1-22%) of Lin^- UCB hematopoietic cells normally express neural markers and are capable of responding to neural cytokines. Neural cytokines did not have effects on hematopoietic cell proliferation; however, we observed generation of neural-like cells, assessed by morphology, and a significant increase in the proportion of cells expressing neural markers. Such neural-like cells, however, retained expression of hematopoietic markers. It seems that under our culture conditions, no actual transdifferentiation of hematopoietic cells into neural cells occurred; instead, the cells generated in culture seem to be hematopoietic cells that acquired neural features upon contact with neurogenic factors. The identity of UCB cells that acquired a neural phenotype is still unclear.