Quantitative variations of CD4+CD25+ cells in Peking duck-white leghorn chimeras based on bone marrow mesenchymal stem cells

Purpose: To develop a chimera via microinjection of poultry xenogeneic bone marrow mesenchymal stem cells (BMMSCs), and to assess its immune tolerance based on variations in proportion of CD4⁺CD25⁺ cells in CD4⁺ cells (specific CD4⁺CD25⁺ cells).
Methods: BMMSCs were flush out from femurs and tibias of Peking ducks with phosphate-buffered saline and cultured. Their morphology was determined with a microscope. Several surface markers (i.e., CD44, CD45, CD71, CD73 and CD34) were used to identify the cells.
Results: The results indicate successful chimera development. CD4⁺CD25⁺ cells derived from the thymus of chimeras were migrated to the spleen and cecal tonsils. This migration was more obvious in chimeras than in the control group, suggesting a more robust immune system in the chimeras. The migration tendency gradually decreased with time. There were significant increases in specific CD4⁺CD25⁺ cells, TGF-β and IL-10 in cecal tonsils throughout the experimental period (30 days). However, in thymus and spleen, variations in specific CD4⁺CD25⁺ cells were observed only on the 1st day post-hatching.
Conclusion: The results suggest a relatively pure BMMSC population without contaminating hematopoietic stem cells. Differentiation of the BMMSCs into osteoblasts and adipocytes was inducible, indicating typical MSC character.

Keywords
Bone marrow mesenchymal stem cells, Immune tolerance, Chimera, Specific CD4⁺CD25⁺ cells, Cell migration