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Erythropoietin responsive progenitors in anaemia

Circulating erythroid progenitors (BFU-E) in five anaemic preterm infants (haemoglobin<100 g/l) were about 2 and 4-4 times as abundant as in 10 preterm infants who were not anaemic and five healthy adults, respectively, and were significantly more responsive to low concentrations of recombinant human erythropoietin (rHuEpo) than those from healthy adults. These results encourage further studies in the use of rHuEpo for the treatment of the anaemia of prematurity. There is interest in the use of recombinant human erythropoietin (rHuEpo) for the prevention and treatment of anaemia of prematurity, which is an hyporegenerative anaemia associated with low concentrations of erythropoietin.' The clinical efficacy of this hormone for the treatment of anaemic premature infants has not yet been shown, though one uncontrolled study suggests that it may increase the packed cell volume.2 Progenitors committed to the erythroid line can be recognised in cell culture systems. These are of two types: the primitive progenitor, the erythroid burst forming unit (BFU-E), which is found in the peripheral circulation, and the more mature progenitor, the erythroid colony forming unit (CFU-E), which is predominantly found in bone marrow. In this study we report the relative numbers of BFU-E progenitors in infants with the anaemia of prematurity, and their response to various doses of rHuEpo, compared with those of progenitors that are present in healthy adults and cord blood from term infants. leosides, insulin, inorganic salts, and antibiotics.3 This system had previously been validated in our laboratory for the growth of erythroid progenitors in blood samples from premature infants (submitted for publication). Six doses of rHuEpo from 0-21U were added to the culture dishes containing a total volume of 1 ml, and all cultures were done in duplicate. The BFU-E were counted through an Olympus CK2 tissue culture microscope and the number of circulating erythroid progenitors was derived from the dishes containing 2IU/ml of rHuEpo. The significance of differences was assessed by Wilcoxon's rank sum test. Ethical approval was given by the local ethics committee. The baseline measurements for the premature infants are shown in table 1. All infants were well and were not being ventilated. No blood transfusions had been given within a week of the blood samples being taken. Results The results show that in the five infants with anaemia of prematurity there were 4-4 times the concentration of circulating erythroid progenitors found in normal healthy adults (p=0 01, table 2). There are twice the number of circulating BFU-E progenitors in anaemic infants (35-5) than in infants who were not anaemic (17-5) although this is not significant. In addition, neonatal progenitors respond at least as well to rHuEpo as those from adult or cord blood (figure). At the low concentrations of 01 and 0 5 IU/ml of rHuEpo there is a significant difference between the responsiveness of progenitors from anaemic preterm infants and those from healthy adults (p=0.05). United Medical and Dental Schools of St Thomas's and Guy's Hospitals, St Thomas's Campus, London SEI 7EH Department of Neonatal Paediatrics A J B Emmerson C M M Stern Department of Haematology N B Westwood R A Rackham T C Pearson Correspondence to: Dr Emmerson. Accepted 30 January 1991 (Arch Dis (hild 1991;66:810-81 1) Patients and methods Two millilitres of venous blood were drawn into preservative free heparin from each of 10 premature infants who were not anaemic and five who were anaemic (haemoglobin < 100 g/l). Five cord blood samples from normal term infants and samples from 10 healthy adult volunteers were collected for comparison. The progenitors were separated by centrifugation over a Ficoll metrizoate density barrier (1077 g/l); 1 x 105 cells from the light density cell fraction were cultured for 14 days at 37°C under 5% carbon dioxide in air in a serum free culture medium with a 2-2% methyl cellulose base, and containing Iscove's modified Dulbecco's medium, bovine serum albumin, cholesterol, sodium pyruvate, transferrin, 1-glutamine, nucTable I Characteristics of the preterm infants studied. Values are expressed as mean (SD) Anaemic Injiants nfaants not anaemic (n=5) (n= 10) Gestational age (weeks) 31 1 (2-2) 29-7 (3 9) Age at time of study (days) 35 4 (15-6) 27-2 (17-7) Birth weight (g) 1670 (450) 1440 (450) Haemoglobin concentration (g/l) 88 (9) 143 (33) Table 2 Median (upper and lower quartile) numbers of circulating erythroid progenitors (BFU-E)/Il0 mononuclear cells at 2IUIml recombinant erythropoietin Subjects Median (quartiles) Anaemic infants (n=5) 35 5 (174-52-4)* Infants not anaemic (n=10) 17-5 (8-5-21-9) Cord blood from term infants (n=5) 10 5 (8 5-11 0) Healthy adults (n=10) 8-0 (20-17-0) *p=0-01 compared with healthy adults. 810 group.bmj.com on February 9, 2018 Published by http://adc.bmj.com/ Downloaded from