Fig. 5
Increased pro-inflammatory signaling pathways between macrophages and MuSC/MPCs is associated with premature differentiation phenotype of MuSC/MPCs in the ischemia-damaged human limb of CLTI patients. A, B UMAP visualization presenting single-cell data gathered from human skeletal muscle tissue samples encompassing 3 CLTI patients under both proximal and distal conditions, along with data from 10 healthy individuals. A A total of 34,950 cells are represented in the UMAP graph. B The cells in clusters 2 and 13, illustrated in purple, exhibit Pax7 (left) and MyoG (right) expression respectively. C Cells from Pax7+ and MyoG+ clusters delineated in B are extracted from total cells and projected with an increased resolution onto a separate UMAP space that contain 5 sub-clusters (cluster 0–4), depicted in different colors. D Within this refined UMAP representation in D, cells in clusters 2 and 4 are denoted as “MPC”, demonstrating the expression of myogenic differentiation markers like MyoG and CKM. Conversely, the cells congregated in clusters 0 and 1 are identified as MuSCs, characterized by the expression of quiescent MuSCs markers Pax7 and Myf5. E The MPC and MuSCs defined in D are separated into healthy (yellow), distal (red), and proximal (blue) conditions for gene expression analyses. Violin plots show the expression of MyoG, MYH3, SPRY1, and CKD6 expression in MPCs (left) and in MuSCs (right), respectively. *P-value < 0.05; **P-value < 0.01. P-values were calculated by the Wilcoxon rank-sum test. F The numbers (left) and interaction strength (right) of inferred signaling interactions calculated by CellChat between macrophages and MuSCs in distal (pink, ischemic) and proximal (blue, non-ischemic) muscles of CLTI patients. G The significant signaling pathways between macrophages and MuSCs/MPCs are ranked based on their inferred strength differences between distal (ischemic) and proximal (non-ischemic) skeletal muscles. Signaling pathways colored in red are enriched in distal muscle, while those colored in blue are enriched in proximal tissues between macrophages and MuSCs/MPCs. H Ligand-receptor interactions inferred by CellPhoneDB between macrophages and MPCs or MuSCs in distal (ischemic) and proximal (non-ischemic) conditions. In distal conditions, we observed stronger pro-inflammatory signaling pathways, such as IL6, CCL4, and SPP1, compared to proximal conditions