Fig. 8
Alterations of protein abundance in the haematopoietic stem cell niche with age. a CXCL12, VCAM1, and FN1 in MSCs and the integrins alpha4, alphaL, beta1, and beta2 (α4, αL, β1, and β2) in HPCs decrease in abundance upon ageing. Age-related changes in connection with nitric oxide (NO) synthesis, the urea cycle, and potential NO crosstalk between MSCs and HPCs is depicted by arrows for unidirectional reactions and strokes for bidirectional reactions. Dotted lines or dotted arrows illustrate reactions for which no enzyme was detected or quantified in this study. The gene names of the respective enzymes are written in capital letters. The colour encodes changes upon ageing, as described in the legend (Spearman's correlation). b Box plot representation of the proteins depicted in a. The dots represent the individual results from younger (age < 30 years) and older (age > 50 years) human subjects. For all box plots, the central line indicates the median, the bottom and top edges of the box the IQR, and the box plot whiskers represent 1.5 times the IQR. Proteins known to have a direct effect on homing or egress of HPCs from or into the bone marrow are shown in the upper and proteins associated with NO signalling and the urea cycle are plotted in the lower graph. An additional box plot depicts the ageing effect on TGFB1 in lymphocytes
