Effects of hypoxia on megakaryocyte progenitors obtained from the umbilical cord blood of term and preterm neonates

Matthew A. Saxonhouse, Lisa M Rimsza, Gary Stevens, Nazanin Jouei, Robert D. Christensen, Martha C. Sola

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Abstract

Background: Placental insufficiency is associated with early-onset thrombocytopenia in preterm neonates. Prior studies demonstrated a reduction in circulating megakaryocyte (Mk) progenitors, suggesting decreased platelet production. We hypothesized that decreased Mk production is the result of a direct inhibitory effect of hypoxia on the proliferation of Mk progenitors, or a hypoxia-induced change in the fetal hematopoietic environment. Objective: To test the effects of hypoxia on the clonogenic maturation of Mk progenitors obtained from term and preterm cord blood CD34 pos cells, either cultured alone or in conjunction with CD34 neg light density mononuclear cells (LDMCs). Methods: CD34 pos cells and CD34 neg LDMCs were isolated from the cord blood of term and preterm deliveries, and mobilized peripheral blood CD34 pos cells were obtained from healthy adults. CD34 pos cells were then cultured alone or co-cultured with CD34 neg LDMCs in a semisolid, serum-free media containing rTpo, IL-3, and IL-6. Cultures were exposed to 20%, 5%, or 1% oxygen for 10-12 days. Mk colonies were then quantified following immunohistochemical staining. Results: Pure CD34 pos cells from preterm (n = 5) and term (n = 5) neonates and from adults (n = 4) generated similar numbers of Mk colonies in all three oxygen concentrations. However, the number of Mk colonies in preterm co-cultures was progressively lower with decreasing O 2 concentrations. Conclusions: Hypoxia did not appear to directly inhibit colony formation of Mk progenitors from preterm and term cord blood CD34 pos cells. However, co-culture studies showed a decrease in Mk colony formation with hypoxia, suggesting an indirect inhibitory effect of hypoxia on Mk clonogenic maturation mediated by non-progenitor cells in the hematopoietic microenvironment.

Original languageEnglish (US)
Pages (from-to)104-108
Number of pages5
JournalBiology of the Neonate
Volume89
Issue number2
DOIs
Publication statusPublished - Feb 2006

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Keywords

  • Hypoxia
  • Megakaryocyte progenitors
  • Neonatal thrombocytopenia
  • Placental insufficiency

ASJC Scopus subject areas

  • Developmental Biology
  • Pediatrics, Perinatology, and Child Health

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