Angiotensin II promotes erythroid proliferation in a three-stage erythroid culture system.

At present, the numbers of cultured erythroid cells obtained from culture systems are not on a scale that can be used for therapeutics since the cultured erythroid cells have limited proliferation capacity. Stromal cells are believed to play important roles during erythropoiesis. Our previous study shows that factors secreted by stromal cells enhance the proliferation capacity of adult erythroid cells in the culture system. Among the identified factors, angiotensinogen is one of the most abundant proteins secreted by the stromal cells. This study aims to investigate the effect of angiotensin II, an angiotensinogen derivative, on the proliferation of erythroid cells. •The receptor for angiotensin II was first checked by PCR analysis. It was expressed in erythroblasts at all stages during differentiation.•To study the effect of angiotensin II, CD34+ hematopoietic stem cells were cultured in a 3-stage erythroid culture system with and without angiotensin II. The addition of angiotensin II to the culture media, from day 0 to 8, significantly increases the numbers of cultured erythroid cells, whereas no difference in enucleation is observed.

Genetic correction of haemoglobin E in an immortalised haemoglobin E/beta-thalassaemia cell line using the CRISPR/Cas9 system.

ß-thalassaemia is one of the most common genetic blood diseases worldwide with over 300 mutations in the HBB gene affecting red blood cell functions. Recently, advances in genome editing technology have provided a powerful tool for precise genetic correction. Generation of patient-derived induced pluripotent stem cells (iPSCs) followed by genetic correction of HBB mutations and differentiation into haematopoietic stem/progenitor cells (HSPCs) offers a potential therapy to cure the disease. However, the biggest challenge is to generate functional HSPCs that are capable of self-renewal and transplantable. In addition, functional analyses of iPSC-derived erythroid cells are hampered by poor erythroid expansion and incomplete erythroid differentiation. Previously, we generated an immortalised erythroid cell line (SiBBE) with unique properties, including unlimited expansion and the ability to differentiate into mature erythrocytes. In this study, we report a highly efficient genetic correction of HbE mutation in the SiBBE cells using the CRISPR/Cas9 system. The HbE-corrected clones restored ß-globin production with reduced levels of HbE upon erythroid differentiation. Our approach provides a sustainable supply of corrected erythroid cells and represents a valuable model for validating the therapeutic efficacy of gene editing systems.

MTAP-related increased erythroblast proliferation as a mechanism of polycythaemia vera.

Polycythaemia vera (PV) is a haematological disorder caused by an overproduction of erythroid cells. To date, the molecular mechanisms involved in the disease pathogenesis are still ambiguous. This study aims to identify aberrantly expressed proteins in erythroblasts of PV patients by utilizing mass spectrometry-based proteomic analysis. Haematopoietic stem cells (HSCs) were isolated from newly-diagnosed PV patients, PV patients who have received cytoreductive therapy, and healthy subjects. In vitro erythroblast expansion confirmed that the isolated HSCs recapitulated the disease phenotype as the number of erythroblasts from newly-diagnosed PV patients was significantly higher than those from the other groups. Proteomic comparison revealed 17 proteins that were differentially expressed in the erythroblasts from the newly-diagnosed PV patients compared to those from healthy subjects, but which were restored to normal levels in the patients who had received cytoreductive therapy. One of these proteins was S-methyl-5'-thioadenosine phosphorylase (MTAP), which had reduced expression in PV patients' erythroblasts. Furthermore, MTAP knockdown in normal erythroblasts was shown to enhance their proliferative capacity. Together, this study identifies differentially expressed proteins in erythroblasts of healthy subjects and those of PV patients, indicating that an alteration of protein expression in erythroblasts may be crucial to the pathology of PV.

Generation of an immortalised erythroid cell line from haematopoietic stem cells of a haemoglobin E/ß-thalassemia patient.

The ß-thalassemia syndromes are the most prevalent genetic disorder globally, characterised by reduced or absent ß-globin chain synthesis. HbE/ß-thalassemia is a subtype of ß-thalassemia with extremely high frequency in Asia. Studying molecular defects behind ß-thalassemia is severely impeded by paucity of material from patients and lack of suitable cell lines. Approaches to derive erythroid cells from induced pluripotent stem cells (iPSCs) created from patients are confounded by poor levels of erythroid cell expansion, aberrant or incomplete erythroid differentiation and foetal/embryonic rather than adult globin expression. In this study we generate an immortalised erythroid cell line from peripheral blood stem cells of a HbE/ß-thalassemia patient. Morphological analysis shows the cells are proerythroblasts with some early basophilic erythroblasts, with no change in morphology over time in culture. The line differentiates along the erythroid pathway to orthochromatic erythroblasts and reticulocytes. Importantly, unlike iPSCs, the line maintains the haemoglobin profile of the patient's red blood cells. This is the first human cellular model for ß-thalassemia providing a sustainable source of disease cells for studying underlying disease mechanisms and for use as drug screening platform, particularly for reagents designed to increase foetal haemoglobin expression as we have additionally demonstrated with hydroxyurea.

Optimization of an erythroid culture system to reduce the cost of in vitro production of red blood cells.

In vitro generation of red blood cells has become a goal for scientists globally. Directly, in vitro-generated red blood cells (RBCs) may close the gap between blood supply obtained through blood donation and high demand for therapeutic uses. In addition, the cells obtained can be used as a model for haematologic disorders to allow the study of their pathophysiology and novel treatment discovery. For those reasons, a number of RBC culture systems have been established and shown to be successful; however, the cost of each millilitre of packed RBC is still extremely high. In order to reduce the cost, we aim to see if we can reduce the number of factors used in the existing culture system. In this study, we examined how well haematopoietic stem cells proliferate and differentiate into mature red blood cells with modified culture system. •Absence of extra heparin or insulin or both from the erythroid differentiation media did not affect haematopoietic stem cell proliferation and differentiation. Therefore, we show that the cost and complexity of erythroid culture can be reduced, which may improve the feasibility of in vitro generation of red blood cells.

Effects of cytochrome P450 2C19 and paraoxonase 1 polymorphisms on antiplatelet response to clopidogrel therapy in patients with coronary artery disease.

Clopidogrel is an antiplatelet prodrug that is recommended to reduce the risk of recurrent thrombosis in coronary artery disease (CAD) patients. Paraoxonase 1 (PON1) is suggested to be a rate-limiting enzyme in the conversion of 2-oxo-clopidogrel to active thiol metabolite with inconsistent results. Here, we sought to determine the associations of CYP2C19 and PON1 gene polymorphisms with clopidogrel response and their role in ADP-induced platelet aggregation. Clopidogrel response and platelet aggregation were determined using Multiplate aggregometer in 211 patients with established CAD who received 75 mg clopidogrel and 75-325 mg aspirin daily for at least 14 days. Polymorphisms in CYP2C19 and PON1 were genotyped and tested for association with clopidogrel resistance. Linkage disequilibrium (LD) and their epistatic interaction effects on ADP-induced platelet aggregation were analysed. The prevalence of clopidogrel resistance in this population was approximately 33.2% (n = 70). The frequencies of CYP2C19*2 and *3 were significantly higher in non-responder than those in responders. After adjusting for established risk factors, CYP2C19*2 and *3 alleles independently increased the risk of clopidogrel resistance with adjusted ORs 2.94 (95%CI, 1.65-5.26; p<0.001) and 11.26 (95%CI, 2.47-51.41; p = 0.002, respectively). Patients with *2 or *3 allele and combined with smoking, diabetes and increased platelet count had markedly increased risk of clopidogrel resistance. No association was observed between PON1 Q192R and clopidogrel resistance (adjusted OR = 1.13, 95%CI, 0.70-1.82; p = 0.622). Significantly higher platelet aggregation values were found in CYP2C19*2 and *3 patients when compared with *1/*1 allele carriers (p = 1.98 × 10(-6)). For PON1 Q192R genotypes, aggregation values were similar across all genotype groups (p = 0.359). There was no evidence of gene-gene interaction or LD between CYP2C19 and PON1 polymorphisms on ADP-induced platelet aggregation. Our findings indicated that only CYP2C19*2 and *3 alleles had an influence on clopidogrel resistance. The risk of clopidogrel resistance increased further with smoking, diabetes, and increased platelet count.

Paraoxonase 1 polymorphisms as the risk factor of coronary heart disease in a Thai population.

OBJECTIVE: Two common polymorphisms of the paraoxonase (PON1) gene, L55M and Q192R, were proven to mitigate atherosclerosis pathogenesis by protecting lipoproteins against peroxidation. This study was to evaluate the associations between both PON1 gene polymorphisms in Thai hyperlipidaemia with and without coronary heart disease (CHD). METHODS: Both PON1 genotypes were determined using PCR-RFLP in 103 healthy control subjects, 103 primary hyperlipidaemia without history of such diseases and 106 angiographically documented CHD patients. RESULTS: The frequencies of PON1 192R allele and 192RR genotype were significantly higher in CHD patients than in normal control subjects (P = 0.009 and 0.037, respectively). The significantly higher frequencies of 55M allele and 55LM genotype were also observed in CHD patients (P = 0.037 and P = 0.034, respectively). The frequencies of both PON1 polymorphisms were not different in primary hyperlipidaemia as compared to the normal control subjects. The odds ratio (OR) of 192RR genotype and 192R allele for CHD were 2.84 (1.17-6.99, P = 0.011) and 1.70 (1.11-2.61, P = 0.009), respectively. The age-adjusted OR for CHD was 2.72 (1.25-5.94, P = 0.012). These frequencies of both PON1 alleles were similar to those seen in other Asian populations. CONCLUSIONS: The association between PON1 polymorphisms and CHD risk was demonstrated in aThai population. These new data underscore the essence of ethnic variations in the interpretation of CHD associated with PON1 polymorphism.

Glutathione and glutathione peroxidase in type 1 diabetic patients.

OBJECTIVE: Diabetic (DM) patients are claimed to be under oxidative stress because of hyperglycemia. The influence of free radical production by this hyperglycemic induction may involve cardiovascular complications in diabetes. The present study aimed to compare the glutathione (GSH) level and glutathione peroxidase (GPx) activity in type 1 DM and a normal healthy group. MATERIAL AND METHOD: GSH level and GPx activity were determined in red cells of 20 subjects of type 1 DM containing fasting plasma glucose (FPG) > or = 140 mg/dL. Twenty healthy normal subjects with normal plasma glucose level (FPG < or = 110 mg/dL) and matched for gender and age served as the control group. These oxidative stress parameters of type 1 DM were compared to a control group by unpaired student's t-test. The association of these parameters with FPG was performed by Pearson product moment correlation. RESULTS: The level of red cell GSH was significantly lower in type 1 DM (p = 0.011) but red cell GPx activity was significantly increased (p = 0.003) when compared to age-matched normal control. The decrement of red cell GSH may be due to the higher rate of consumption of GSH, increasing GPx activity or a reduction of pentose phosphate pathway, stimulated by insulin, resulting in lowered GSH recycle. The correlation between FPG and GSH in type I diabetic patients compared with healthy normal subjects was also observed and it was found that there was a negative correlation, but not found between FPG and GPx activity. CONCLUSION: The present finding suggested that type 1 DM patients were susceptible to oxidative stress and higher blood glucose level had an association with free-radical-mediated lipid peroxidation. Therefore, any means that can reduce oxidative stress may be beneficial for slow progression of cardiovascular complication in type 1 diabetic patients.

Plasma lipid peroxidation and antioxidiant nutrients in type 2 diabetic patients.

BACKGROUND AND OBJECTIVE: Observation shows diabetic patients to be more prone to oxidative stress because of hyperglycemia. The elevation of free radical production by this hyperglycemic production may exacerbate cardiovascular complication in diabetes. This study aims to investigate the oxidative stress related parameters in type 2 DM. Since the effects of glycemic control and cardiovascular complications in DM on these parameters has been not fully determined, the comparison between plasma MDA (malondialdehyde) and antioxidant nutrients with their age-matched normal healthy group may be used to determine the susceptibility of oxidative stress in this type of DM. MATERIAL AND METHOD: MDA and antioxidant nutrients (vitamin A, C, E and beta-carotene) were analyzed in plasma of 19 subjects with poorly controlled type 2 DM (fasting plasma glucose [FPG] > 180 mg/dl), 26 subjects with fairly controlled type 2 DM (FPG < or = 180 mg/dl), and 20 subjects with type 2 DM complicated coronary heart disease (CHD) who were matched for age and gender. Twenty healthy subjects with normal plasma glucose level (FPG < 110 mg/dl) and matched for age and gender served as a control group. In all groups of DM these oxidative stress parameters were compared to a normal group. RESULTS: The plasma MDA levels were significantly higher in all types of DM compared to age-matched normal control. Plasma antioxidant vitamin C and E significantly lower only in poorly controlled and CHD complicated type 2 DM, respectively. The mean of plasma vitamin E level was lowest in type 2 DM complicated with CHD. No significant differences in both plasma vitamin A and beta-carotene were noted between any types of DM and age-matched normal healthy group. The positive correlation between MDA and FPG was demonstrated in most group of patients with their normal subjects except in fairly controlled type 2 DM and negative correlation between vitamin E and FPG was also demonstrated in type 2 DM with CHD. CONCLUSION: These findings suggested that diabetic patients were susceptible to oxidative stress and higher plasma glucose level had an association with free radical-mediated lipid peroxidation. The lowest level of vitamin E in type 2 DM complicated with CHD indicated that oxidative stress played an important role in cardiovascular complication and vitamin E supplementation may be necessary for treatment and prevention in this group of diabetics.