Research Paper Volume 4, Issue 9 pp 606—619

Figure 5. Comparing competence of thymic T-lymphopoiesis associated with BM progenitor ages or their niche ages in repopulating IL7R^−/− host mouse thymus in a BMT microenvironment.

(A) A schematic diagram of workflow. (B) Left panel shows the gross appearance of young IL7R^−/− mouse thymus size from a representative experiment, 5 weeks after infusion with PBS, or equal numbers of 2-, 8-, 12-, 18-, or 22-month-old WT BM cells. Right panel shows a summary of total thymocyte number in young IL7R^−/− host mouse thymus, derived from donor WT mouse BM cells of different ages. (C) Left panel shows the gross appearance of 1- (left column) and 12-month-old (right column) IL7R^−/− mouse thymus size from a representative experiment, 5 weeks after transplantation with equal numbers of ~2-month-old WT BM cells (top row) or PBS (bottom row). Right panel shows a summary of total thymocyte number derived from young donor WT mouse BM cells in IL7R^−/− host niches of different ages. (D) Left panel shows the linear regression of thymocyte number derived from donor WT BM cells of different ages in young IL7R^−/− host niches (blue line, Exp-A) and from young donor WT BM cells in IL7R^−/− host niches of different ages (red line, Exp-B). Test for equal slopes for the blue (slope −3.72 ~ −1.28) and red (slope −7.23 ~ −3.97) gives a (2-sided) p-value of 0.016 (significantly different). Right panel shows donor-derived thymocyte numbers from 11-to-13-month-old donor WT BM cells in young IL7R^−/− host niches (left bar) and young donor WT BM cells in 11-to-13-month-old IL7R^−/- host niches (right bar). Data show mean ± SEM in all bar graphs, n = IL7R^−/− host animal number, each triangle and square in C represents one animal. Experiments were repeated over 5 times.