Objective: To study whether human placenta contains hematopoietic stem/progenitor cells (HSPCs), and analyze phenotypes of lymphocyte subpopulations in the placenta.
Methods: Nucleated cells from fresh human placenta were analyzed for phenotypes of HSPCs and lymphocyte subpopulations by flow cytometry (FCM). And CD(34)(+) cells were sorted from human placenta nucleated cells by FCM or MiniMACS.
Results: (1) CD(34)(+) cells, CD(34)(+)/CD(38)(+) cells, and CD(34)(+)/CD(38)(-) cells from a human placenta were 8.8, 4.6 and 11.9 times higher than those from umbilical cord blood (UCB), respectively. (2) The yields and purity of CD(34)(+) cells isolated from human placenta by FCM sorting system were (63.05 +/- 10.14)% and (86.39 +/- 11.27)%, respectively. (3) Lymphocytes, T cells (CD(3)(+)/CD(2)(+)), B cells (CD(19)(+)), Th cells (CD(3)(+), CD(4)(+)), and Th/Ts ratio in the placenta tissue were apparently lower than those in the UCB, while the CD(8)(+)/CD(28)(-) T suppressor cells were higher in the placenta than in the UCB.
Conclusions: Human placenta is rich in HSPCs, and has important hematopoietic function in ontogeny. It is probable that human placenta would be graft resource for HSPCs transplantation. CD(8)(+)/CD(28)(-) T suppressor cells might play an important role in feto-maternal immunologic tolerance.