Reprogramming of human peripheral blood monocytes to erythroid lineage by blocking of the PU-1 gene expression

Novel heterozygous SPI1c.538C>T p.(Leu180Phe) variant causes PU.1 haploinsufficiency leading to agammaglobulinemia

PU.1 is an Ets family transcription factor crucial for hematopoietic cell fate. Complete PU.1 deficiency lethally arrests lympho- and myelopoiesis in mice. Individuals with SPI1 heterozygous loss-of-function variants exhibit disrupted gene expression patterns associated with B cell development. We identified the vertical transmission of a heterozygous SPI1c.538C>T p.(L180F) variant in a Finnish family. The index patient and his mother had severe bacterial infections, agammaglobulinemia, and low myeloid and plasmacytoid dendritic cell counts. The variant carrier sister had slightly reduced B cell counts, isolated IgA deficiency, and reduced dendritic cell counts. All individuals had diminished PU.1 protein expression in monocytes. In vitro studies showed that PU.1 L180F variant is less expressed and predominantly located in the cytoplasm. PU.1 WT mainly interacts with chromatin and centrosome-associated proteins, while the L180F variant showed fewer interactions. Our findings describe a novel PU.1 variant leading to agammaglobulinemia with variable penetrance.

Blood Pharming – eine realistische Option?

Die Bluttransfusion ist ein wesentlicher und unersetzlicher Teil der modernen Medizin. Jedoch stellt vor allem bei Patienten mit sehr seltenen Blutgruppenkonstellationen der Mangel an Blutprodukten auch heute noch ein wichtiges Gesundheitsproblem weltweit dar. Um diesem Problem entgegenzutreten, versucht man seit einiger Zeit künstlich rote Blutzellen zu generieren. Diese haben potenzielle Vorteile gegenüber Spenderblut, wie z. B. ein verringertes Risiko für die Übertragung von Infektionskrankheiten. Diese Übersicht fasst die aktuellen Entwicklungen über den Prozess der Erythropoese, die Expansionsstrategien der erythrozytären Zellen, der verschiedenen Quellen für ex vivo expandierte Erythrozyten, die Hürden für die klinische Anwendung und die zukünftigen Möglichkeiten der Anwendung zusammen.

Hematopoietic Reprogramming Entangles with Hematopoiesis

Hematopoiesis generally refers to hematopoietic development in fetuses and adults, as well as to hematopoietic stem cell differentiation into progeny lineages. The multiple processes that generate diverse hematopoietic cells have been considered to be unidirectional. However, many reports have recently demonstrated that these processes are not only reversible but also interconvertible via cell reprogramming. The cell reprogramming that occurs in hematopoietic cells is termed hematopoietic reprogramming. We focus on both autogenous and artificial hematopoietic reprogramming under physiological and pathological conditions that is mainly directed by the actions of transcription factors (TFs), chemical compounds, or extracellular cytokines. A comprehensive understanding of hematopoietic reprogramming will help us not only to generate desirable cells for cell therapy but also to further analyze normal and malignant hematopoiesis.

Molecular Interaction Networks to Select Factors for Cell Conversion

The process of identifying sets of transcription factors that can induce a cell conversion can be time-consuming and expensive. To help alleviate this, a number of computational tools have been developed which integrate gene expression data with molecular interaction networks in order to predict these factors. One such approach is Mogrify, an algorithm which ranks transcriptions factors based on their regulatory influence in different cell types and tissues. These ranks are then used to identify a nonredundant set of transcription factors to promote cell conversion between any two cell types/tissues. Here we summarize the important concepts and data sources that were used in the implementation of this approach. Furthermore, we describe how the associated web resource ( www.mogrify.net ) can be used to tailor predictions to specific experimental scenarios, for instance, limiting the set of possible transcription factors and including domain knowledge. Finally, we describe important considerations for the effective selection of reprogramming factors. We envision that such data-driven approaches will become commonplace in the field, rapidly accelerating the progress in stem cell biology.

Research advances in erythrocyte regeneration sources and methods in vitro

Erythrocytes (red blood cells, RBCs) facilitate gas exchange in the lungs and transport oxygen to the tissues. The human body must maintain erythrocyte regeneration to support metabolically active cells and tissues. In many hematological diseases, erythrocyte regeneration is impaired. Researchers have studied erythrocyte regeneration for many years both in vivo and in vitro. In this review, we summarize the sources and main culture methods for generating mature and functional red blood cells in vitro. Hematopoietic stem cells (HSCs), embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) are classic sources for erythrocyte regeneration. In addition, alternative sources such as immortalized adult human erythroid cell lines and transformed fibroblasts have also been generated and have produced functional red blood cells. The culture systems for erythrocytes differ among laboratories. Researchers hope that improvements in culture techniques may contribute to improved RBC outcomes for blood transfusions, drug delivery and the treatment of hematological diseases.