Developmental changes in pluripotent hematopoietic progenitors.
In rats of various prenatal and postnatal ages, the number of pluripotent hematopoietic progenitor cells (CFU-GEMM) in the blood, liver, spleen and bone marrow was determined, and their cell-cycle characteristics compared. Similar to human neonates, fetal and neonatal rats had a much higher concentration of CFU-GEMM in the blood than did mature animals (2060-8320 CFU-GEMM/ml blood at 15 days gestation vs. 20-120/ml at six weeks of age, P less than 0.001). However, the total body pool of CFU-GEMM/g body weight was significantly less in fetal animals than in adults (2010 CFU-GEMM/g, range 850-2650/g at 20 days gestation vs. 10 550/g, range 7900-14,900/g at 6 weeks, P less than 0.001). The proportion of CFU-GEMM killed by tritiated thymidine was 2% (0-12%) in adults rats, whereas younger animals had progressively higher rates, reaching over 90% (68-100) in fetal animals (P less than 0.001). Following incubation with Interleukin 3 (IL-3), the thymidine suicide rate of CFU-GEMM from mature rates increased significantly (from 4 +/- 3% to 53 +/- 4%, P less than 0.01), but no increase was detected in CFU-GEMM from fetal rats. These features might contribute to the limited capacity of neonatal subjects to significantly increase production of the progeny of CFU-GEMM.
Christensen
R D
RD
Department of Pediatrics, University of Utah School of Medicine, Salt Lake City 84132.
D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D002453:Cell Cycle; D003114:Colony-Forming Units Assay; D005333:Fetus / Q000166:cytology; D005865:Gestational Age; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000187:drug effects; D006413:Hematopoietic System / Q000166:cytology / Q000187:drug effects / Q000254:growth & development*; D007377:Interleukin-3 / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
D007377:Interleukin-3