Primitive hematopoietic cell populations reside in the spleen: Studies in the pig, baboon, and human

Academic Article


  • Objective: We previously observed high levels (>40%) of multilineage hematopoietic cell chimerism following spleen transplantation across full MHC barriers in immunosuppressed miniature swine. We therefore investigated the spleen as a source of hematopoietic progenitor cells (HPCs). Materials and methods: Specific cell-surface markers were used to identify HPCs in the spleen and bone marrow (BM) of young adult (n = 15) and fetal (n = 9) miniature swine by flow cytometry. Hoechst dye-effluxing side population (SP) cells were analyzed in adult spleen, BM, and blood for their expression of c-kit. Functional HPC activity of varying repopulation potential in vitro was investigated by the ability of spleens and BM to give rise to colony-forming units (CFUs) and cobblestone area-forming cells (CAFCs) in long-term stromal cultures. Studies were also carried out on baboon and human spleens and BM. Results: Spleen c-kit+ cells co-expressed more lymphoid markers, but equal myeloid markers, when compared with BM c-kit+ cells. BM and spleen both contained significant percentages of c-kit+ SP cells. Although the frequency of early-forming CFUs in the spleen was only 0.1 to 1.3% of that in the BM, the frequency of CAFCs developing after 8 weeks in culture was comparable to that of BM. Secondary CFUs in long-term culture-initiating cell assays confirmed the presence of long-term repopulating cells at comparable frequencies in spleen and BM. Similar findings were found with regard to baboon and human spleen cells. Conclusion: The adult spleen is a relatively rich source of very primitive HPCs, possibly hematopoietic stem cells (HSCs), and may be of therapeutic value. © 2006 International Society for Experimental Hematology.
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    Author List

  • Dor FJMF; Ramirez ML; Parmar K; Altman EL; Huang CA; Down JD; Cooper DKC
  • Start Page

  • 1573
  • End Page

  • 1582
  • Volume

  • 34
  • Issue

  • 11