Stem cells--a source of adult red blood cells for transfusion purposes: present and future

Recent updates of stem cell-based erythropoiesis

Blood transfusions are now an essential part of modern medicine. Transfusable red blood cells (RBCs) are employed in various therapeutic strategies; however, the processes of blood donation, collection, and administration still involve many limitations. Notably, a lack of donors, the risk of transfusion-transmitted disease, and recent pandemics such as COVID-19 have prompted us to search for alternative therapeutics to replace this resource. Originally, RBC production was attempted via the ex vivo differentiation of stem cells. However, a more approachable and effective cell source is now required for broader applications. As a viable alternative, pluripotent stem cells have been actively used in recent research. In this review, we discuss the basic concepts related to erythropoiesis, as well as early research using hematopoietic stem cells ex vivo, and discuss the current trend of in vitro erythropoiesis using human-induced pluripotent stem cells.

Stem cell therapy for patients with diabetes: a systematic review and meta-analysis of metabolomics-based risks and benefits

Background

There is a general agreement that to ensure promising results of stem cell therapy in patients with diabetes, one must first understand its risks and benefits; thus, if the risk is sufficiently low along with many benefits, it can lead to developing a novel therapeutic approach based on sound science.

Methods

A systematic review and meta-analysis was performed using all available clinical trials to determine the benefits and risks associated with stem cell therapy in patients with diabetes (both T1DM and T2DM). An extensive search was conducted across several databases using all MeSH words regarding stem cell therapy and diabetes.

Results

In T2DM, a large body of research has shown that stem cell therapy has improved the insulin daily requirement and glycosylated hemoglobin (HbA1C) levels, and also has a positive effect on these variables, but has a negative impact on c-peptide. Hence, in T1DM, stem cell therapy improves c-peptide and HbA1C levels and has a positive effect on these variables, but has a negative impact on insulin daily requirement.

Conclusions

A total of 639 cells have the ability to self-renew and differentiate into a variety of cells, including blood, heart, nervous and cartilage cells. Paradoxically, it has been stated that these cells also have the potential to form cancer cells. These possible risks warrant caution by both medical specialists and patients while proceeding with the treatment; thus, it is critically crucial to conduct further research on stem cell therapy but with first considering their risk and benefits.

Cholinergic and cytoprotective signaling cascades mediate the mitigative effect of erythropoietin on acute radiation syndrome

The present investigation aimed to evaluate the radiomitigative efficacy of the recombinant human erythropoietin (EPO) against acute radiation syndrome (ARS) in a rat model. Rats were irradiated with a single sublethal dose of γ-radiation (7 Gy; total body irradiation; TBI) on the 1st day of experimental course, then received EPO (5000 IU/kg; i.p.) 24 h after irradiation, and rats were observed for 30 days of survival analysis. Administration of EPO improved 30-day survival, alleviated TBI-induced myelosuppression and pancytopenia, by augmenting lymphocytes and other white blood cells in the peripheral blood of rats, while bone marrow and spleen cellularity were restored. EPO post-exposure treatment alleviated hepatotoxicity biomarkers and restored splenic function. EPO abrogated radiation-induced oxidative stress through the upregulation of the cholinergic anti-inflammatory nicotinic acetylcholine receptor (α-7-nAChR) and the pro-survival Janus kinase-2 and signal transducers and activators of transcription JAK-2/STAT-3 signaling mediated via enhancing nuclear factor erythroid-2 related factor-2 (Nrf-2) cytoprotective machinery in liver and spleen of irradiated rats. Moreover, EPO treatment prevented hepatic and splenic apoptosis. The present study establishes the implication of α-7-nAChR-JAK-2/STAT-3-Nrf-2 signaling cascade in the radiomitigative potential of EPO against ARS.

Application of mutant JAK2V617F for in vitro generation of red blood cells

BACKGROUND

In vitro generation of red blood cells (RBCs) from hematopoietic stem cells (HSCs) has been reported, but the collection of 1 × 10(5) to 1 × 10(6) CD34+ cells present in cord and peripheral blood is too small for expansion to 1 × 10(12) cells in 1 unit of RBCs. We transduced JAK2V617F gene, the most common mutation with polycythemia vera (PV), into cord blood-derived CD34+ cells. This PV model was expected to increase cell proliferation without the addition of erythropoietin (EPO) in early phase of differentiation.

STUDY DESIGN AND METHODS

Empty vector (control), wild-type JAK2 (wJAK2), and mutant JAK2V617F (mJAK2) were transduced into CD34+ cells using a lentivirus system. The CD34+ cells were then differentiated to the RBCs in a culture system. The cells were analyzed for cell number, differential count, and morphologic changes. Cultured RBCs were tested for oxygen equilibrium.

RESULTS

wJAK2- and mJAK2-transduced cells showed higher proliferation capacity until Day 21 than control cells; interestingly, only mJAK2-transduced cells were highly increased on Day 7 during EPO-free culture. However, both wJAK2- and mJAK2-tranduced cells had more delayed differentiation than control, but they had a higher portion of completely matured RBCs and orthochromatic erythroblasts. Furthermore, mJAK2-tranduced cells showed more differentiation into RBCs than wJAK2-transduced cells and they had a normal hemoglobin dissociation curve.

CONCLUSION

This is the first trial to use a PV erythropoiesis model for RBC differentiation from stem cells. The transduction of HSCs with mJAK2 increased their proliferation capacity in EPO-free culture conditions. This model may also be useful for investigating the pathogenesis of PV.

Anemia and Transfusion in Critical Care

Objective:

The objective of this report is to review the physiology and management of anemia in critical care. Selected publications on physiology and transfusion related to anemia and critical care, including the modern randomized trials of conservative versus liberal transfusion policy, were used. Anemia is compensated and tolerated in most critically ill patients as long as oxygen delivery is at least twice oxygen consumption. There are risks to blood transfusion which can be minimized by blood banking practice. The availability of cultured red cells may allow correction of anemia without significant risk. The benefit of transfusion in anemia must be weighted against the risk in any specific patient.

Conclusion and Recommendation:

In a criticially ill patient, anemia should be managed to avoid oxygen supply dependency (oxygen delivery less than twice comsumption) and to maintain moderate oxygen delivery reserve (DO2/VO2 > 3).

Advances in cellular technology in the hematology field: What have we learned so far?

Despite the advances in the hematology field, blood transfusion-related iatrogenesis is still a major issue to be considered during such procedures due to blood antigenic incompatibility. This places pluripotent stem cells as a possible ally in the production of more suitable blood products. The present review article aims to provide a comprehensive summary of the state-of-the-art concerning the differentiation of both embryonic stem cells and induced pluripotent stem cells to hematopoietic cell lines. Here, we review the most recently published protocols to achieve the production of blood cells for future application in hemotherapy, cancer therapy and basic research.

Role of Erythropoietin and Other Growth Factors in Ex Vivo Erythropoiesis

Erythropoiesis is a vital process governed through various factors. There is extreme unavailability of suitable donor due to rare phenotypic blood groups and other related complications like hemoglobinopathies, polytransfusion patients, and polyimmunization. Looking at the worldwide scarcity of blood, especially in low income countries and the battlefield, mimicking erythropoiesis using ex vivo methods can provide an efficient answer to various problems associated with present donor derived blood supply system. Fortunately, there are many ex vivo erythropoiesis methodologies being developed by various research groups using stem cells as the major source material for large scale blood production. Most of these ex vivo protocols use a cocktail of similar growth factors under overlapping growth conditions. Erythropoietin (EPO) is a key regulator in most ex vivo protocols along with other growth factors such as SCF, IL-3, IGF-1, and Flt-3. Now transfusable units of blood can be produced by using these protocols with their set of own limitations. The present paper focuses on the molecular mechanism and significance of various growth factors in these protocols that shall remain helpful for large scale production.

Manufacturing blood ex vivo: a futuristic approach to deal with the supply and safety concerns

Blood transfusions are routinely done in every medical regimen and a worldwide established collection, processing/storage centers provide their services for the same. There have been extreme global demands for both raising the current collections and supply of safe/adequate blood due to increasingly demanding population. With, various risks remain associated with the donor derived blood, and a number of post collection blood screening and processing methods put extreme constraints on supply system especially in the underdeveloped countries. A logistic approach to manufacture erythrocytes ex-vivo by using modern tissue culture techniques have surfaced in the past few years. There are several reports showing the possibilities of RBCs (and even platelets/neutrophils) expansion under tightly regulated conditions. In fact, ex vivo synthesis of the few units of clinical grade RBCs from a single dose of starting material such as umbilical cord blood (CB) has been well established. Similarly, many different sources are also being explored for the same purpose, such as embryonic stem cells, induced pluripotent stem cells. However, the major concerns remain elusive before the manufacture and clinical use of different blood components may be used to successfully replace the present system of donor derived blood transfusion. The most important factor shall include the large scale of RBCs production from each donated unit within a limited time period and cost of their production, both of these issues need to be handled carefully since many of the recipients among developing countries are unable to pay even for the freely available donor derived blood. Anyways, keeping these issues in mind, present article shall be focused on the possibilities of blood production and their use in the near future.

Establishment of immortalized human erythroid progenitor cell lines able to produce enucleated red blood cells

Transfusion of red blood cells (RBCs) is a standard and indispensable therapy in current clinical practice. In vitro production of RBCs offers a potential means to overcome a shortage of transfusable RBCs in some clinical situations and also to provide a source of cells free from possible infection or contamination by microorganisms. Thus, in vitro production of RBCs may become a standard procedure in the future. We previously reported the successful establishment of immortalized mouse erythroid progenitor cell lines that were able to produce mature RBCs very efficiently. Here, we have developed a reliable protocol for establishing immortalized human erythroid progenitor cell lines that are able to produce enucleated RBCs. These immortalized cell lines produce functional hemoglobin and express erythroid-specific markers, and these markers are upregulated following induction of differentiation in vitro. Most importantly, these immortalized cell lines all produce enucleated RBCs after induction of differentiation in vitro, although the efficiency of producing enucleated RBCs remains to be improved further. To the best of our knowledge, this is the first demonstration of the feasibility of using immortalized human erythroid progenitor cell lines as an ex vivo source for production of enucleated RBCs.

Alternative blood products and clinical needs in transfusion medicine

The primary focus of national blood programs is the provision of a safe and adequate blood supply. This goal is dependent on regular voluntary donations and a regulatory infrastructure that establishes and enforces standards for blood safety. Progress in ex vivo expansion of blood cells from cell sources including peripheral blood, cord blood, induced pluripotent stem cells, and human embryonic stem cell lines will likely make alternative transfusion products available for clinical use in the near future. Initially, alloimmunized patients and individuals with rare blood types are most likely to benefit from alternative products. However, in developed nations voluntary blood donations are projected to be inadequate in the future as blood usage by individuals 60 years and older increases. In developing nations economic and political challenges may impede progress in attaining self-sufficiency. Under these circumstances, ex vivo generated red cells may be needed to supplement the general blood supply.

Compartmental hollow fiber capillary membrane-based bioreactor technology for in vitro studies on red blood cell lineage direction of hematopoietic stem cells

Continuous production of red blood cells (RBCs) in an automated closed culture system using hematopoietic stem cell (HSC) progenitor cell populations is of interest for clinical application because of the high demand for blood transfusions. Previously, we introduced a four-compartment bioreactor that consisted of two bundles of hollow fiber microfiltration membranes for transport of culture medium (forming two medium compartments), interwoven with one bundle of hollow fiber membranes for transport of oxygen (O(2)), carbon dioxide (CO(2)), and other gases (forming one gas compartment). Small-scale prototypes were developed of the three-dimensional (3D) perfusion cell culture systems, which enable convection-based mass transfer and integral oxygenation in the cell compartment. CD34(+) HSC were isolated from human cord blood units using a magnetic separation procedure. Cells were inoculated into 2- or 8-mL scaled-down versions of the previously designed 800-mL cell compartment devices and perfused with erythrocyte proliferation and differentiation medium. First, using the small-scale 2-mL analytical scale bioreactor, with an initial seeding density of 800,000 cells/mL, we demonstrated approximately 100-fold cell expansion and differentiation after 7 days of culture. An 8-mL laboratory-scale bioreactor was then used to show pseudocontinuous production by intermediately harvesting cells. Subsequently, we were able to use a model to demonstrate semicontinuous production with up to 14,288-fold expansion using seeding densities of 800,000 cells/mL. The down-scaled culture technology allows for expansion of CD34(+) cells and stimulating these progenitors towards RBC lineage, expressing approximately 40% CD235(+) and enucleation. The 3D perfusion technology provides an innovative tool for studies on RBC production, which is scalable.

Ex-vivo expansion of red blood cells: how real for transfusion in humans?

Blood transfusion is indispensable for modern medicine. In developed countries, the blood supply is adequate and safe but blood for alloimmunized patients is often unavailable. Concerns are increasing that donations may become inadequate in the future as the population ages prompting a search for alternative transfusion products. Improvements in culture conditions and proof-of-principle studies in animal models have suggested that ex-vivo expanded red cells may represent such a product. Compared to other cell therapies transfusion poses the unique challenge of requiring great cell doses (2.5×10(12) cells vs 10(7) cells). Although production of such cell numbers is theoretically possible, current technologies generate red cells in numbers sufficient only for safety studies. It is conceived that by the time these studies will be completed, technical barriers to mass cell production will have been eliminated making transfusion with ex-vivo generated red cells a reality.

Proof of principle for transfusion of in vitro-generated red blood cells

In vitro RBC production from stem cells could represent an alternative to classic transfusion products. Until now the clinical feasibility of this concept has not been demonstrated. We addressed the question of the capacity of cultured RBCs (cRBCs) to survive in humans. By using a culture protocol permitting erythroid differentiation from peripheral CD34(+) HSC, we generated a homogeneous population of cRBC functional in terms of their deformability, enzyme content, capacity of their hemoglobin to fix/release oxygen, and expression of blood group antigens. We then demonstrated in the nonobese diabetes/severe combined immunodeficiency mouse that cRBC encountered in vivo the conditions necessary for their complete maturation. These data provided the rationale for injecting into one human a homogeneous sample of 10(10) cRBCs generated under good manufacturing practice conditions and labeled with (51)Cr. The level of these cells in the circulation 26 days after injection was between 41% and 63%, which compares favorably with the reported half-life of 28 ± 2 days for native RBCs. Their survival in vivo testifies globally to their quality and functionality. These data establish the proof of principle for transfusion of in vitro-generated RBCs and path the way toward new developments in transfusion medicine. This study is registered at http://www.clinicaltrials.gov as NCT0929266.

Phenotypic definition of the progenitor cells with erythroid differentiation potential present in human adult blood

In Human Erythroid Massive Amplification (HEMA) cultures, AB mononuclear cells (MNC) generate 1-log more erythroid cells (EBs) than the corresponding CD34^pos cells, suggesting that MNC may also contain CD34^neg HPC. To clarify the phenotype of AB HPC which generate EBs in these cultures, flow cytometric profiling for CD34/CD36 expression, followed by isolation and functional characterization (colony-forming-ability in semisolid-media and fold-increase in HEMA) were performed. Four populations with erythroid differentiation potential were identified: CD34^posCD36^neg (0.1%); CD34^posCD36^pos (barely detectable-0.1%); CD34^negCD36^low (2%) and CD34^negCD36^neg (75%). In semisolid-media, CD34^posCD36^neg cells generated BFU-E and CFU-GM (in a 1 : 1 ratio), CD34^negCD36^neg cells mostly BFU-E (87%) and CD34^posCD36^pos and CD34^negCD36^low cells were not tested due to low numbers. Under HEMA conditions, CD34^posCD36^neg, CD34^posCD36^pos, CD34^negCD36^low and CD34^negCD36^neg cells generated EBs with fold-increases of ≈9,000, 100, 60 and 1, respectively, and maturation times (day with >10% CD36^highCD235a^high cells) of 10–7 days. Pyrenocytes were generated only by CD34^neg/CD36^neg cells by day 15. These results confirm that the majority of HPC in AB express CD34 but identify additional CD34^neg populations with erythroid differentiation potential which, based on differences in fold-increase and maturation times, may represent a hierarchy of HPC present in AB.

Under HEMA conditions, self-replication of human erythroblasts is limited by autophagic death

The number of erythroblasts generated ex-vivo under human-erythroid massive-amplification conditions by mononuclear cells from one unit of adult blood (~10(10)) are insufficient for transfusion (~10(12) red cells), emphasizing the need for studies to characterize cellular interactions during culture to increase erythroblast production. To identify the cell populations which generate erythroblasts under human-erythroid-massive-amplification conditions and the factors that limit proliferation, day 10 non-erythroblasts and immature- and mature-erythroblasts were separated by sorting, labelled with carboxyfluorescein-diacetate-succinimidyl-ester and re-cultured either under these conditions (for proliferation, maturation and/or apoptosis/autophagy determinations) or in semisolid media (for progenitor cell determination). Non-erythroblasts contained 54% of the progenitor cells but did not grow under human-erythroid-massive-amplification conditions. Immature-erythroblasts contained 25% of the progenitor cells and generated erythroblasts under human-erythroid-massive-amplification conditions (FI at 48 h=2.57±1.15). Mature-erythroblasts did not generate colonies and died in human-erythroid-massive-amplification conditions. In sequential sorting/re-culture experiments, immature-erythroblasts retained the ability to generate erythroblasts for 6 days and generated 2-5-fold more cells than the corresponding unfractionated population, suggesting that mature-erythroblasts may limit erythroblast expansion. In co-cultures of carboxyfluorescein-diacetate-succinimidyl-ester-labelled-immature-erythroblasts with mature-erythroblasts at increasing ratios, cell numbers did not increase and proliferation, maturation and apoptotic rates were unchanged. However, Acridine Orange staining (a marker for autophagic death) increased from ~3.2% in cultures with immature-erythroblasts alone to 14-22% in cultures of mature-erythroblasts with and without immature-erythroblasts. In conclusion, these data identify immature-erythroblasts as the cells that generate additional erythroblasts in human-erythroid-massive-amplification cultures and autophagy as the leading cause of death limiting the final cellular output of these cultures.

Banking of pluripotent adult stem cells as an unlimited source for red blood cell production: potential applications for alloimmunized patients and rare blood challenges

The transfusion of red blood cells (RBCs) is now considered a well-settled and essential therapy. However, some difficulties and constraints still occur, such as long-term blood product shortage, blood donor population aging, known and yet unknown transfusion-transmitted infectious agents, growing cost of the transfusion supply chain management, and the inescapable blood group polymorphism barrier. Red blood cells can be now cultured in vitro from human hematopoietic, human embryonic, or human-induced pluripotent stem cells (hiPSCs). The highly promising hiPSC technology represents a potentially unlimited source of RBCs and opens the door to the revolutionary development of a new generation of allogeneic transfusion products. Assuming that in vitro large-scale cultured RBC production efficiently operates in the near future, we draw here some futuristic but realistic scenarios regarding potential applications for alloimmunized patients and those with a rare blood group. We retrospectively studied a cohort of 16,486 consecutive alloimmunized patients (10-year period), showing 1 to 7 alloantibodies with 361 different antibody combinations. We showed that only 3 hiPSC clones would be sufficient to match more than 99% of the 16,486 patients in need of RBC transfusions. The study of the French National Registry of People with a Rare Blood Phenotype/Genotype (10-year period) shows that 15 hiPSC clones would cover 100% of the needs in patients of white ancestry. In addition, one single hiPSC clone would meet 73% of the needs in alloimmunized patients with sickle cell disease for whom rare cryopreserved RBC units were required. As a result, we consider that a very limited number of RBC clones would be able to not only provide for the need for most alloimmunized patients and those with a rare blood group but also efficiently allow for a policy for alloimmunization prevention in multiply transfused patients.

A research agenda for malaria eradication: basic science and enabling technologies

Today's malaria control efforts are limited by our incomplete understanding of the biology of Plasmodium and of the complex relationships between human populations and the multiple species of mosquito and parasite. Research priorities include the development of in vitro culture systems for the complete life cycle of P. falciparum and P. vivax and the development of an appropriate liver culture system to study hepatic stages. In addition, genetic technologies for the manipulation of Plasmodium need to be improved, the entire parasite metabolome needs to be characterized to identify new druggable targets, and improved information systems for monitoring the changes in epidemiology, pathology, and host-parasite-vector interactions as a result of intensified control need to be established to bridge the gap between bench, preclinical, clinical, and population-based sciences.

Red blood cells from pluripotent stem cells for use in transfusion

The use of donated red blood cells in transfusion is a well-established cellular therapy. However, problems including insufficient supply, transfusion-transmitted infections and the need for immunological matching hamper even in the best services. These issues may be eliminated by using pluripotent stem cells to generate universal donor group O, Rhesus D-negative red blood cells. Human embryonic stem cells can be maintained and expanded indefinitely and can, therefore, produce the very large cell numbers required for this application. Red blood cell production is also an attractive goal for pluripotent stem cell-derived therapeutics because it is a well-characterized single cell suspension, lacking nucleated cells and with a low expression of HLA molecules. Much progress has been made; however, a number of challenges remain including scale-up, clinical effectiveness and product safety.