Erythropoietin in premature infants

The regulation of erythropoiesis during the first three months of life was studied in 30 premature infants who had haemoglobin concentrations which were lower than in term in fants of the same postdelivery age. Erythropoietin and erythropoiesis inhibitors were measured by means of an exhypoxic polycythaemic mouse bioassay. The percentage of haemoglobin F was determined as well. An increased erythropoietin level was detected only in six infants older than six weeks, whose blood haemoglobin concentration was lower than 100 g/l, while in serum from other babies erythropoietin was undetectable by the method used. Erythropoiesis inhibitors were present in 80% of the samples tested. The results presented indicate that in premature infants erythropoiesis is regulated through erythropoietin and that inhibitors of erythropoiesis take part in this regulation as well, but that the haemoglobin level at which erythropoietin is increased is lower in preterm infants than in term babies.     

ERYTHROPOIETIN IN PREMATURE INFANTS

ABSTRACT. The regulation of erythropoiesis during the first three months of life was studied in 30 premature infants who had haemoglobin concentrations which were lower than in term infants of the same postdelivery age. Erythropoietin and erythropoiesis inhibitors were measured by means of an exhypoxic polycythaemic mouse bioassay. The percentage of haemoglobin F was determined as well. An increased erythropoietin level was detected only in six infants older than six weeks, whose blood haemoglobin concentration was lower than 100 g/l, while in serum from other babies erythropoietin was undetectable by the method used. Erythropoiesis inhibitors were present in 80% of the samples tested. The results presented indicate that in premature infants erythropoiesis is regulated through erythropoietin and that inhibitors of erythropoiesis take part in this regulation as well, but that the haemoglobin level at which erythropoietin is increased is lower in preterm infants than in term babies.     

Acquired amegakaryocytic thrombocytopaenia in a child

A boy aged 5 years is described with amegakaryocytic thrombocytopaenia, which was associated with defective granulopoiesis and erythropoiesis, but did not evolve into marrow aplasia. Marrow cultures confirmed the presence of abnormalities in each of the haemopoietic lineages and identified defective maturation of megakaryocytic precursors. The was no evidence of a humoral inhibitor of megakaryopoiesis. The patient's blood cell counts responded to treatment with oxymetholone.     

Physiology of erythropoietin during mammalian development

Growth is a fundamental process of mammalian development. Several observations regarding regulation of erythropoiesis during growth are not easily explained by the hypoxia-erythropoietin (Epo) concept. This review focuses primarily on this aspect of the physiology of Epo. The question is raised of whether this regulation during growth is based on the hypoxia-Epo mechanism alone, or whether Epo acts in concert with general growth-promoting factors, particularly growth hormone (GH) and the insulin-like growth factors (IGF-I and -II). Supporting the latter hypothesis is the observation that the Epo and GH/IGF systems are activated by hypoxia and share similar receptors and pathways. Recent studies indicate that human fetal and infant growth is stimulated by GH, IGF-I and IGF-II. Epo, GH and IGFs are expressed early in fetal life. Although the rate of erythropoiesis in the fetus is high, serum Epo levels are low. The Epo response to hypoxia in the fetus and neonate is reduced compared with adults. Following delivery the Epo levels vary between species, probably related to the oxygen transport capacity of the hemoglobin (Hb) mass. IGF-I levels are low in the fetus and increase slowly following birth, except in preterm infants in whom the levels decline. In all mammals Hb declines following birth, giving rise to "early anemia". Except in the human, Epo levels increase proportionally with the fall in Hb, but there is a discrepancy between the curves for serum immunoreactive Epo (siEpo) and for erythropoiesis stimulating factors (ESF): the latter include other stimulatory factors in addition to Epo. Hypertransfusion of mice in the period of "early anemia" suppresses siEpo, but not ESF and erythropoiesis, as it does in adult mice. GH and IGF-I have direct effects on erythropoiesis in vitro and act particularly at the later stages of red cell differentiation. IGF-I acts synergistically with Epo, and its effects are most marked when Epo levels are low. Human recombinant (rhu) IGF-I stimulates erythropoiesis in neonatal rats, but not in newborn mice and lambs. In adult mice, in hypophysectomized rats and in mice with end-stage renal failure, however, a stimulatory effect of this growth factor was found on red cell production. RhuGH stimulates erythropoiesis in GH-deficient short children. CONCLUSION: Fetal and early postnatal erythropoiesis are dependent on factors in addition to Epo. The likely candidates are GH and IGF-I. The in vitro stimulating effects of these factors on erythropoiesis are convincing, but more data are needed on the in vivo effects.     

ERYTHROPOIESIS IN THE NEWBORN

The normal newborn infant displays active erythropoiesis at birth. Within a few days erythropoietic activity is greatly reduced and remains so for several weeks. During this time the occurrence of anaemia does not evoke an erythropoietic response comparable with that seen in older children. It has been suggested that diminished production of erythropoietin by the infant following transition from the hypoxic intrauterine environment to the atmosphere accounts for these observations. Technical and ethical limitations on plasma erythropoietin assays have prevented adequate study of the mechanisms controlling erythropoiesis in this age group, and urinary erythropoietin assays appeared to offer a feasible alternative. This paper describes urinary assays in normal and anaemic infants, giving details of the technique. The results were inconclusive. The reasons for this are discussed and further studies proposed.     

URINARY EXCRETION OF ERYTHROPOIETIN AND ERYTHROPOIESIS INHIBITORS IN THE NEONATAL PERIOD

ABSTRACT. Lindemann, R. (Pediatric Research Institute, Department of Pediatrics, University Hospital, Rikshospitalet, Oslo, Norway). Urinary excretion of erythropoietin and erythropoiesis inhibitors in the neonatal period. Acta Paediatr Scand, 63:764, 1974. —The regulation and suppression of erythropoiesis in the neonatal period has been studied. Urines from normal newborn babies were collected from time of delivery and during the first week of life. Both erythropoietin (ESF) and an erythropoiesis inhibiting factor (EIF) were separated by Sephadex gel filtration. The factors were tested according to days after birth and related to the creatinine coefficient. The exhypoxic polycythemic mouse bioassay was used and the results were expressed as the per cent incorporation of ⁵⁹Fe into newly formed red blood cells. A demonstrable amount of ESF was found only in the urine voided the first day of life, indicating that the ESF production is shut off immediately after birth. From the third day of Life, a marked inhibitory effect of the EIF fractions was found. This may indicate a dual mechanism behind the decrease in neonatal erythropoiesis: a shut off of the ESF production and the appearence of erythropoiesis inhibitors.     

In-vitro studies on the kinetics of bone-marrow erythropoesis during the first trimester of life (Trimenonreduction)]

This study tries to give further insight into the mechanism and location of the physiological reduction of the bone marrow erythropoiesis during the first trimester (Trimenonreduction). Methods utilized included red blood values, bone marrow morphology, 3H-Thymidine Autoradiography, Feulgen-cytophotometry and 3H-, 14C-Thymidine double labelling techniques of bone marrow erythroblasts of healthy children of different age groups. Besides already known techniques we used especially a modification of the double labelling techniques, developed in our laboratories. We draw the following conclusions from our results: 1. Newborns have a higher rate of bone marrow erythropoiesis in comparison with normal controls of other ages. The reduction of the bone marrow erythropoiesis starts already in the first 2 days of life. 2. The reduction of the bone marrow erythropoiesis in the investigated infants in the second week of life was about to one fifth of values which proved to be normal for healthy older children. 3. This reduction is caused partially by prolongation of proliferation and maturation phases of erythroblasts, partially by a decrease of new erythroblast-formation from the stem cell pool. Medium values of DNA-synthesistime of infants with the highest reduction is double compared with values of healthy controls in vitro. 4. The decrease of cell proliferation and maturation during the reduction of the bone-marrow erythropoiesis includes all precursors and all phases of the cell cycle equally. In the first few days of life however it seems that the decrease of DNA synthesizing erythroblasts surpasses the reduction of maturing cells. 5. An ineffectiveness of erythropoiesis could not be found responsible for the reduction. 6. The reduction in erythropoiesis is seen in those steps in which other autors found stimulations by erythropoietin. Therefore this study supports the thesis, that the trimenonreduction is caused by a lack of erythropoietin stimulation. 7. The sequence of the trimenon reduction in humans is different from results found in animals.     

Hepatic Erythropoiesis in Infants of Diabetic Mothers: A Morphometric Study

Hepatic erythropoietic tissue is inversely proportional to the gestational age both in infants of diabetic mothers and in control cases. Hepatic erythropoietic and indices range from 17.8 in fetuses and babies before 28 week's gestational age to about 1.0 in fetuses and babies at 40-42 week's gestational age. The decline with gestational age is gradual in the last 10-12 weeks of in utero development. Infants of diabetic mothers who are normally grown have normal amounts of erythropoiesis in their livers. At term, large infants of diabetic mothers have excessive hepatic erythropoiesis. Hypoxia, a frequent feature in infants of diabetic mothers, is probably responsible for the increased erythropoiesis, but an alternate mechanism may be that hyperinsulinemia directly stimulates erythroid precursors or erythropoietin production.     

Hepatic erythropoiesis in infants of diabetic mothers: a morphometric study

Hepatic erythropoietic tissue is inversely proportional to the gestational age both in infants of diabetic mothers and in control cases. Hepatic erythropoietic and indices range from 17.8 in fetuses and babies before 28 weeks' gestational age to about 1.0 in fetuses and babies at 40-42 weeks' gestational age. The decline with gestational age is gradual in the last 10-12 weeks of in utero development. Infants of diabetic mothers who are normally grown have normal amounts of erythropoiesis in their livers. At term, large infants of diabetic mothers have excessive hepatic erythropoiesis. Hypoxia, a frequent feature in infants of diabetic mothers, is probably responsible for the increased erythropoiesis, but an alternate mechanism may be that hyperinsulinemia directly stimulates erythroid precursors or erythropoietin production.     

Twin transfusion syndrome causing cutaneous erythropoiesis

Two cases of twin transfusion syndrome are described in which the donor twin exhibited blueberry muffin-like macules and papules associated with cutaneous erythropoiesis. No evidence was found in either case for intrauterine viral infection, the most common cause of cutaneous erythropoiesis. Cutaneous erythropoiesis is these two cases is considered to be due to persistence or reactivation of fetal dermal erythropoiesis secondary to prolonged, severe intrauterine anemia.     

Ineffective erythropoiesis underlies the clinical heterogeneity of congenital dyserythropoietic anemia type II (CDA II)

BACKGROUND: Congenital dyserythropoietic anemia type II (CDA II) is an autosomal recessive disease, and is the most common CDA. The qualitative and quantitative defects of erythropoiesis in CDA II, as estimated by the hematological and biochemical parameters at the time of diagnosis, may not reflect the heterogeneity of the disease course of each patient. METHODS: Three pediatric patients with CDA II are herein presented, having an heterogeneous clinical course. In addition to bone marrow morphology, Ham test and SDS-PAGE of erythrocyte membrane protein, the present study also examined erythroid marrow activity, by measuring serum Erythropoietin (Epo), soluble Transferrin Receptors (sTfR) concentrations and Reticulocyte Production Index (RPI). RESULTS: All patients demonstrated the same pattern of ineffective erythropoiesis, having increased Epo (350-389 IU/L), sTfR concentrations (6.2-7.8 mg/L) and low RPI values (0.8-1.3). Erythron expansion was expressed by RPI values nearly twofold higher than normal values in parallel to raised sTfR and high Epo production. Despite the same degree of ineffective erythropoiesis seen in all patients, the severity of the clinical course was diverse in terms of frequency and clinical relevance of transfusion needs. CONCLUSION: An analysis of the parameters expressing ineffective erythropoiesis in CDA II can provide a better understanding of the degree of dyserythropoiesis, however it is not useful for predicting the clinical course of disease in patients, because the underlying genetic heterogeneity of this disorder remains obscure.     

Treatment of refractory aplastic anemia with plasmapheresis: report of a case in childhood with review of the literature

Treatment of aplastic anemia may raise considerable problems in some patients. This report concerns a boy whose illness started at 11 years of age. At first admission laboratory data were: hemoglobin 7.5 g/l, and counts of leucocytes, neutrophils and platelets were 2.3, 0.6, and 8 x 10(9)/l, respectively. His bone marrow was hypoplastic with sparse erythropoiesis. The patient did not respond to traditional medical treatment. Serum contained a high concentration of erythropoietin but no antibodies against erythropoietin. The patient's serum did neither alone, nor supported with recombinant erythropoietin, stimulate erythropoiesis in a bioassay, suggesting that some factor(s) inhibiting erythropoietic activity was present. Based on this hypothesis, plasma exchange was performed. After 26 weeks of plasmapheresis the hematological parameters were normalized. We conclude that plasmapheresis might be an alternative in treatment of resistant aplastic anemia. Further diagnostic tools to identify patients who might benefit from such a treatment are required.     

Iron-deficient erythropoiesis in neonatal rats.

Anemia in premature infants is extremely common. Precise quantitation of iron status and determination of iron incorporation into erythrocytes are important in monitoring therapy for anemia in premature infants, especially when treating with recombinant human erythropoietin (rhEPO). However, the traditional indices of the iron status have limited usefulness in this population. The goal of the current work is to develop an experimental animal model system that addresses the clinical issue relating to quantitation of iron delivery to erythrocytes. We first determined normal hematological values for nontreated, dam-suckled Sprague-Dawley rats by measuring markers of erythropoiesis and iron status during the first 12 postnatal days (PND). The experimental group of rats were administered parenteral rhEpo (430 IU.kg(-1). day(-1)) for 8 days (from PND 4 until PND 12) in the absence (rhEpo(-Fe)) or presence (rhEpo(+Fe)) of oral iron supplementation (6 mg.kg(-1).day(-1)). Rat pups receiving oral iron only (control(+Fe)) and pups that were sham fed with the orogastric tube (control(-Fe)) were included as controls. Hematological parameters were measured in blood and bone marrow. In a pattern similar to that seen in premature infants during the first 2 months of life, the levels of these hematopoietic markers were dynamic and changed during the first 12 PND. After challenging experimental animals with subcutaneous rhEpo, evidence of iron-deficient erythropoiesis was seen in the rhEpo(-Fe) group. Red blood cell levels and absolute reticulocyte counts were higher in both groups receiving rhEpo as compared with the controls. However, the rhEpo(-Fe) group experienced a lower hemoglobin level, a lower mean red cell volume, a greater red cell distribution width, and a higher zinc protoporphyrin/heme (ratio than the rhEpo(+Fe) group. The neonatal rat is an excellent model of iron-deficient erythropoiesis and will be useful in designing future mechanistic studies examining the interplay between iron and erythropoiesis in the anemic, iron-challenged premature neonate.     

THE PATTERN OF REACTIVATED FETAL ERYTHROPOIESIS IN BONE MARROW DISORDERS OF CHILDHOOD1

ABSTRACT. The expression of fetal characteristics of erythropoiesis (haemoglobin F concentration, haemoglobin A₂ concentration, haemoglobin F cells, globin chain synthesis, carboanhydrase isoenzyme B, hexokinase isoenzymes, erythrocyte membrane antigens of the iI- and the ABH-system) was examined in red cells of twelve patients with different bone marrow disorders (juvenile chronic myeloid leukaemia (JCML), erythroleukaemia (EL), acute myelogenous leukaemia (AML), aplastic anaemia (AA) and Diamond-Blackfan anaemia (DB)). In JCML and EL all red cell parameters studied appeared to be fetal including the distribution of hexokinase isoenzymes. No fetal signs could be found in red cells of patients with AML. In two patients with DB who were treated by transfusion no fetal erythropoiesis could be detected. In one patient with DB under cortisone treatment i-antigen, ABH-antigens, haemoglobin F concentration, globin chain synthesis and hexokinase isoenzyme distribution were of the fetal or mixed type. In patients with AA only slight elevations of haemoglobin F were detectable. The nearly total reversion to fetal erythropoiesis in JCML and EL seems to be a part of the disorder itself, whereas in the other disorders the reactivation of fetal erythropoiesis could be the result of an erythropoietic stress.     

CELL POPULATIONS IN THE BONE MARROW OF GUINEA PIG FETUSES WITH INTRAUTERINE GROWTH RETARDATION

Bone marrow smears and blood samples were examined in guinea pig fetuses in which intrauterine growth retardation (IUGR) had been induced by uterine artery ligation and compared with those of control (well-grown) fetuses from uterine horns with intact circulation. Differential bone marrow cell counts were obtained from a count of 300 cells per smear and blood samples were assayed for hemoglobin concentration and 2,3-diphosphoglycerate (DPG). Results of blood assays showed no difference in hemoglobin concentration. DPG levels were reduced in the IUGR guinea pigs (.05), which could be a consequence of decreased glucose availability or represent an adaptation to reduced oxygen availability. Comparisons of bone marrow counts revealed an increase in total erythrocyte precursors (.05) and a decrease in total granulocytic precursors (.05) in IUGR fetuses. Within the erythroid lineage there was a significant increase in late (orthochromatic) erythroblasts (.005) in the IUGR animals compared with control animals. The granulocytic lineage of the IUGR fetuses showed a significant decrease in mature neutrophils (.05) and eosinophilic precursors (.05) compared with controls. These data suggest that the hypoxic stress of uterine artery ligation leads to an increase in medullary erythropoiesis. In concert with a previous study that showed a reduction in hepatic erythropoiesis, these data suggest a precocious shift of the anatomic site of erythropoiesis from the liver to the bone marrow under conditions of hypoxia.     

Effect of recombinant human growth hormone (rhGH) on hemoglobin concentration in children with idiopathic growth hormone deficiency-related anemia

Normocytic-normochromic anemia (NC/NC) has been attributed to impaired bone marrow erythropoiesis in growth hormone (GH)-deficient patients. Moreover, the GH/insulin-like growth factor-1 (IGF-1) axis has been implicated in erythropoiesis regulation. In this retrospective multicenter study, we evaluated the incidence of NC/NC anemia in 279 children (196 boys), median age 10.52 years, with isolated idiopathic GH deficiency, and the effect of recombinant human growth hormone (rhGH) therapy on hemoglobin levels. At 6-month intervals, we recorded the Hb standard deviation score (Hb-SDS), the IGF-1-SDS, weight, height, and pubertal stage. Forty-one boys and 7 girls had NC/NC anemia before starting substitutive therapy (-2.59 SD). The Hb-SDS was significantly increased (P<0.05) after 12 months of rhGH therapy. The effect of rhGH continued up to 48 months (-0.39 SD), at which point all children had normal hemoglobin values. In conclusion, rhGH therapy resulted in normal hemoglobin values in all children enrolled in the study. These data support the concept that the GH/IGF-1 axis promotes erythropoiesis in vivo.     

Oral iron supplementation in preterm infants treated with erythropoietin

BACKGROUND: It is not known whether a moderate dose of oral iron supplementation would further enhance erythropoiesis in recombinant human erythropoietin (EPO)-treated very low-birthweight (VLBW) infants. METHODS: In total, 24 preterm infants with birthweights 750-1499 g were enrolled at the age of 14-28 days to receive 400 IU/kg per week EPO subcutaneously for 8 weeks. The infants were randomly allocated either to receive oral iron supplementation 4 mg/kg per day or to serve as controls. RESULTS: Hemoglobin and the absolute reticulocyte count in the iron supplementation and the control groups remained identical throughout the study period, whereas serum ferritin was significantly lower in the control group at study exit and follow up. Rates of treatment success (no need for transfusion and hemoglobin never below 8 g/dL) also did not differ between the groups. CONCLUSIONS: In this study we did not find a clear advantage in a moderate dose of oral iron supplementation on erythropoiesis in EPO-treated VLBW infants. Whether a higher dose would lead to enhanced erythropoiesis remains to be answered.     

Diamond-blackfan anemia: etiology, pathophysiology, and treatment

Diamond-Blackfan anemia (DBA) is manifested by a wide variety of clinical and in vitro abnormalities. Despite this biological diversity, the hematological phenotype is remarkably similar for all patients and consists of a normochromic-macrocytic anemia in early childhood, reticulocytopenia, and a normocellular marrow with a selective deficiency of red cell precursors. Fetal hemoglobin is usually increased, distributed heterogeneously, has a fetal G gamma/A gamma pattern, and is associated with increased expression of red cell i antigen. Although most cases are sporadic, there are examples of autosomal recessive and autosomal dominant inheritance patterns. Approximately 70% of patients with DBA respond to prednisone, and many can be maintained on tapered doses. Those who are steroid-dependent at high dosage as well as those who do not respond are managed on a transfusion and iron chelation program. Claims of efficacy for other therapies, such as cyclosporine or high-dose intravenous methylprednisolone, require substantiation. Bone marrow transplantation has been successfully performed in patients who have tissue-matched donors, and the procedure cures the anemia. Recombinant growth factors may be a therapy of the future. Regarding pathophysiology, initial reports of humoral or cellular inhibitors of erythropoiesis were not confirmed in all laboratories. However, some patients have lymphocyte dysfunction with decreased T cells, decreased T4/T8 ratios, and defective lymphocyte-mediated suppression of lymphoproliferation. A large body of data indicates that the erythroid stem cells are intrinsically defective in DBA, and they are partly or completely refractory to erythropoietin. The role of elevated red cell adenosine deaminase activity in the pathogenesis of this abnormal erythropoiesis is not clear, but this finding is characteristic of the syndrome in most patients. Present studies using recombinant growth factors have demonstrated a diversity of defects in erythropoiesis in patients with DBA. Blocks in red cell production and red cell maturation were seen at various levels along the differentiation pathway. Of clinical interest, interleukin-3 has a corrective effect in vitro on the aberrant marrow erythropoiesis of steroid-refractory patients, and, hence, it may have therapeutic application.     

Erythropoiesis of very low-birth-weight infants dependent on prenatal growth rate and protein status

Kivivuori SM, Järvenpää AL, Salmenperä L, Viinikka L, Siimes MA. Erythropoiesis of very low-birth-weight infants dependent on prenatal growth rate and protein status. Acta Paediatr 1994; 83:13–18. Stockholm. ISSN 0803–5253
This study investigated erythropoiesis in very low-birth-weight infants with special reference to the role of protein status in the regulation of erythropoiesis in 22 appropriate- and 11 small-for-gestational-age infants. Blood sampies were drawn at three and six weeks of age. The serum concentrations of erythropoietin, estimated by a solid-phase enzyme immunoassay, were similar in the two groups at both study ages. The total circulating erythrocyte volume and the serum concentration of prealbumin were higher in the appropriate- than in the small-for-gestational-age infants at three and six weeks of age. The former group had a better protein status, although their protein intake was similar or lower. We conclude that erythropoiesis in very low-birth-weight infants is influenced more by protein status and prenatal growth than by serum concentration of erythropoietin.     

Hematopoietic Progenitors in Children with End-Stage Renal Disease

Bone marrow and circulating eythroid progenitors (BFU-E) in six anemic children with end-stage renal disease (ESRD) were 2.0 and 1.9 times as abundant, respectively, as in six age-matched normal controls and were significantly more responsive in vitro to low concentrations of recombinant human etythropoietin (rHuEpo) than those from the controls. After 4 weeks of rHuEpo therapy, both the number and the in vitro rHuEpo response of circulating BFU-E in the ESRD patients returned to normal control values. The numbers of bone narrow and circulating granulocyte-monocyte progenitors in the ESRD patients before and after rHuEpo therapy were comparable to those of normal controls. There was 120 inhibition of in vitro erythropoiesis by either the patients' serum or medium conditioned by their mononuclear cells. These results demonstrate a significant abundance and an increased rHuEpo sensitivity of BFU-E in anemic children with ESRD with no evidence of the presence of uremic inhibitors to erythropoiesis.