Expression and affinity of homing-related molecules on steady-state adult and neonate human PB CD34+ cells and their SRC activity.
Although the vast majority of hematopoietic progenitor cells (HPCs) reside within the bone marrow (BM), a small number of HPCs also continuously circulate in the peripheral blood (PB). The examination of the fate of blood-borne HPCs in parabiotic mice, which are surgically conjoined and share a common circulation, recently revealed that steady-state PB HPCs play a physiological role in, at least, the functional re-engraftment of unconditioned BM. To assess the possibility that human HPCs have a similar function, in this study we examined the expression level and affinity of the homing-related molecules, as well as the SCID mouse reconstituting cell (SRC) activity of human PB CD34+ cells, and compared adults with neonates. There was no remarkable difference between adults and neonates in the expression of E- and/or P-selectin ligands by PB CD34+ cells or in these cells' affinity to VCAM-1. In contrast, the expression level of CXCR4 on PB CD34+ cells was much lower in adults than in neonates. Adult cells also showed a much lower SRC activity than neonates. These results suggest that human PB HPCs may contribute to steady-state hematopoiesis in the BM of neonates to some extent, but not so much in adults.
Hirayama
Fumiya
F
Osaka Red Cross Blood Center, Japan. fhirayam@land.linkclub.or.jp
Yano
Maki
M
Tanaka
Mitsunobu
M
Yasui
Kazuta
K
Horie
Yoshinori
Y
Matsumoto
Kayoko
K
Nagao
Nobuo
N
Tani
Yoshihiko
Y
D000328:Adult; D000818:Animals; D018952:Antigens, CD34 / Q000096:biosynthesis* / Q000276:immunology*; D015815:Cell Adhesion Molecules / Q000096:biosynthesis / Q000276:immunology*; D005786:Gene Expression Regulation; D006410:Hematopoiesis / Q000502:physiology*; D006412:Hematopoietic Stem Cells / Q000276:immunology* / Q000502:physiology; D006801:Humans; D007231:Infant, Newborn; D051379:Mice; D016513:Mice, SCID; D019718:Receptors, CXCR4 / Q000096:biosynthesis / Q000276:immunology*
D018952:Antigens, CD34; D015815:Cell Adhesion Molecules; D019718:Receptors, CXCR4