Trends and targets of various types of stem cell derived transfusable RBC substitution therapy: Obstacles that need to be converted to opportunity

3' UTR-truncated HMGA2 promotes erythroblasts production from human embryonic stem cells

Cultured red blood cells represent an alternative resource for blood transfusions. However, important issues such as low yields and high costs remain. Recently, gene editing of hematopoietic stem cells has been conducted to induce erythroid differentiation in vitro for producing sufficient RBCs to meet the imbalance in blood supply and demand. The differentiation and expansion of hematopoietic stem and progenitor cells are regulated by transcription factors, such as high mobility group AT-hook 2 (HMGA2). In this study, we utilized CRISPR/Cas9 to establish a doxycycline-inducible HMGA2-expressing human embryonic stem cell (hESC) line. In a defined erythroid differentiation system, HMGA2 prolonged erythroid differentiation in vitro, enabling extensive expansion of human erythroblasts. The erythroblasts derived from the HMGA2-expressing hESC line are rich in polychromatic and orthochromatic erythroblasts expressing mostly α- and γ-globin and have the capacity to differentiate into RBCs. Our findings highlight the potential of combining hematopoietic transcription factors with genome editing techniques to enhance RBC production.

Characterization of immortalized bone marrow erythroid progenitor adult (imBMEP-A)-The first inducible immortalized red blood cell progenitor cell line derived from bone marrow CD71-positive cells

BACKGROUND AIMS

Ex vivo production of red blood cells (RBCs) represents a promising alternative for transfusion medicine. Several strategies have been described to generate erythroid cell lines from different sources, including embryonic, induced pluripotent, and hematopoietic stem cells. All these approaches have in common that they require elaborate differentiation cultures whereas the yield of enucleated RBCs is inefficient.

METHODS

We generated a human immortalized adult erythroid progenitor cell line derived from bone marrow CD71-positive erythroid progenitor cells (immortalized bone marrow erythroid progenitor adult, or imBMEP-A) by an inducible expression system, to shorten differentiation culture necessary for terminal erythroid differentiation. It is the first erythroid cell line that is generated from direct reticulocyte progenitors and demonstrates robust hemoglobin production in the immortalized state.

RESULTS

Morphologic analysis of the immortalized cells showed that the preferred cell type of the imBMEP-A line corresponds to hemoglobin-producing basophilic erythroblasts. In addition, we were able to generate a stable cell line from a single cell clone with the triple knockout of RhAG, RhDCE and KELL. After removal of doxycycline, part of the cells differentiated into normoblasts and reticulocytes within 5-7 days.

CONCLUSIONS

Our results demonstrate that the imBMEP-A cell line can serve as a stable and straightforward modifiable platform for RBC engineering in the future.

Generation of Rh D-negative blood using CRISPR/Cas9

Blood supply shortages, especially the shortage of rare blood types, threaten the current medical system. Research on stem cells has shed light on in vitro blood cell manufacturing. The in vitro production of universal red blood cells (RBCs) from induced pluripotent stem cells (iPSCs) has become the focus of transfusion medicine. To obtain O-type Rh D-negative blood, we developed O-type Rh D-negative human (h)iPSCs using homology-directed repair (HDR)-based CRISPR/Cas9. HuAiPSCs derived from human umbilical arterial endothelial cells and showing haematopoietic differentiation preferences were selected for gene modification. Guide RNAs (gRNAs) were selected, and a donor template flanked by gRNA-directed homologous arms was set to introduce a premature stop code to RHD exon 2. CRISPR/Cas9 gene editing has resulted in the successful generation of an RHD knockout cell line. The HuAiPSC-A1-RHD-/- cell line was differentiated into haematopoietic stem/progenitor cells and subsequently into erythrocytes in the oxygen concentration-optimized differentiation scheme. HuAiPSC-A1-RHD-/- derived erythrocytes remained positive for the RBC markers CD71 and CD235a. These erythrocytes did not express D antigen and did not agglutinate in the presence of anti-Rh D reagents. In conclusion, taking the priority of haematopoietic preference hiPSCs, the HDR-based CRISPR/Cas9 system and optimizing the erythroid-lineage differentiation protocol, we first generated O-type Rh D-negative universal erythrocytes from RHD knockout HuAiPSCs. Its production is highly efficient and shows great potential for clinical applications.

Mesenchymal stem cell transfusion: Possible beneficial effects in COVID-19 patients

SARS-CoV-2 attaches to the angiotensin-converting enzyme 2 (ACE-2) receptor on human cells. The virus causes hypercytokinemia, capillary leak, pulmonary edema, acute respiratory distress syndrome, acute cardiac injury, and leads to death. Mesenchymal stem cells (MSCs) are ACE-2 negative cells; therefore, can escape from SARS-CoV-2. MSCs prevent hypercytokinemia and help the resolution of the pulmonary edema and other damages occurred during the course of COVID-19. In addition, MSCs enhance the regeneration of the lung and other tissues affected by SARS-CoV-2. The case series reported beneficial effect of MSCs in COVID-19 treatment. However, there are some concerns about the safety of MSCs, particularly referring to the increased risk of disseminated intravascular coagulation, and thromboembolism due to the expression of TF/CD142. Prospective, randomized, large scale studies are needed to reveal the optimum dose, administration way, time, efficacy, and safety of MSCs in the COVID-19 treatment.

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.

An Overview of Current Position on Cell Therapy in Transfusion Science and Medicine: From Fictional Promises to Factual and Perspectives from Red Cell Substitution to Stem Cell Therapy

Stem cell therapy is a relatively novel field of investigation, in which either differentiated cells or stem cells capable of differentiation are transplanted into an individual with the objective of yielding specific cell types in the damaged tissue and consequently restoring its function. The most successful example of cell therapy is hematopoietic stem cell transplantation, leading to regeneration of a patient's blood cells, now a widely established procedure for many oncologic and non-oncologic diseases. Innovative cell-based therapies are being developed to replace, regenerate or repair injured, absent, or diseased tissues and organs. However, cell therapy bioproducts are based on their inherent biological features such as proliferation, migratory, capability, plasticity, and capacity of self-renewal, posing serious challenges during such bioproduct development. The extraordinary promise of stem cells for future treatments of otherwise intractable diseases has raised great hope and expectations in patients, advocates, physicians, and researchers alike. However, despite thousands of scientific publications and research programs, increased efforts need to be put into the identification of the factors involved, biological mechanisms and materials that affect safety/ efficacy, and into the design of cost-effective methods for the harvesting, expansion, manipulation and purification of the cells.