title: Erythroid progenitor cells expanded from peripheral blood without mobilization or preselection: molecular characteristics and functional competence.
abstract: BACKGROUND
  Continued development of in-vitro procedures for expansion and differentiation of erythroid progenitor cells (EPC) is essential not only in hematology and stem cell research but also virology, in light of the strict erythrotropism of the clinically important human parvovirus B19.
  
  
  RESULTS
  We cultured EPC directly from ordinary blood samples, without ex vivo stem cell mobilization or CD34+ cell in vitro preselection. Profound increase in the absolute cell number and clustering activity were observed during culture. The cells obtained expressed the EPC marker combination CD36, CD71 and glycophorin, but none of the lymphocyte, monocyte or NK markers. The functionality of the generated EPC was examined by an in vitro infection assay with human parvovirus B19, tropic for BFU-E and CFU-E cells. Following infection (i) viral DNA replication and mRNA production were confirmed by quantitative PCR, and (ii) structural and nonstructural proteins were expressed in >50% of the cells. As the overall cell number increased 100-200 fold, and the proportion of competent EPC (CD34+ to CD36+) rose from <0.5% to >50%, the in vitro culture procedure generated the EPC at an efficiency of >10,000-fold. Comparative culturing of unselected PBMC and ex vivo-preselected CD34+ cells produced qualitatively and quantitatively similar yields of EPC.
  
  
  CONCLUSIONS
  This approach yielding EPC directly from unmanipulated peripheral blood is gratifyingly robust and will facilitate the study of myeloid infectious agents such as the B19 virus, as well as the examination of erythropoiesis and its cellular and molecular mechanisms.
authors.affiliation: Department of Virology, Haartman Institute, University of Helsinki and Helsinki University Laboratory Division, Helsinki, Finland.
authors.forename: Claudia
authors.initials: C
authors.lastname: Filippone
authors.forename: Rauli
authors.initials: R
authors.lastname: Franssila
authors.forename: Arun
authors.initials: A
authors.lastname: Kumar
authors.forename: Leena
authors.initials: L
authors.lastname: Saikko
authors.forename: Panu E
authors.initials: PE
authors.lastname: Kovanen
authors.forename: Maria
authors.initials: M
authors.lastname: Söderlund-Venermo
authors.forename: Klaus
authors.initials: K
authors.lastname: Hedman
mesh_terms: D015703:Antigens, CD / Q000096:biosynthesis; D018952:Antigens, CD34 / Q000096:biosynthesis; D018955:CD36 Antigens / Q000096:biosynthesis; D018929:Cell Culture Techniques; D015672:Erythroid Precursor Cells / Q000166:cytology*; D005434:Flow Cytometry / Q000379:methods; D005821:Genetic Techniques; D006021:Glycophorins / Q000096:biosynthesis; D019650:Hematopoietic Stem Cell Mobilization / Q000379:methods; D006801:Humans; D017992:Parvovirus / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011990:Receptors, Transferrin / Q000096:biosynthesis; D057905:Stem Cell Research; D013234:Stem Cells
chemical_list: D015703:Antigens, CD; D018952:Antigens, CD34; D018955:CD36 Antigens; C068126:CD71 antigen; D006021:Glycophorins; D011990:Receptors, Transferrin