Fig. 1

CD34⁺/CD31⁻ cells are present in human wound granulation tissue. A Overview of human granulation tissue cellularity and identification of CD34-expressing cells shown as uniform manifold approximation and projection (UMAP) plots. B Unsupervised clustering of fibroblast subtypes and expression of CD34. C Immunofluorescence staining of a representative granulation tissue section from a chronic lower limb wound in a 53-year-old male patient. The higher magnification detail (right image) indicates the presence of CD34⁺/CD31⁻ single and CD34⁺/CD31⁺ double positive cells. D Immunofluorescence staining of the same specimen. The higher magnification detail (right image) shows the proximity of CD68⁺ cells to CD34⁺ cells. E, F Flow cytometry analysis of single-cell suspensions from human granulation tissue samples (n = 6). E Left panel: Frequency of CD45⁺ and CD45⁻ cells shown as a percentage of viable granulation tissue cells. Right panel: Frequency of CD31⁺ cells shown as a percentage of CD45⁻ cells. F Left panel: frequency of CD34⁺ endothelial progenitor cells shown as a percentage of CD45⁻/CD31⁺ endothelial cells. Right panel: frequency of CD34⁺ cells shown as a percentage of CD45⁻/CD31⁻/CD90⁺ cells. Details of patients are described in Supplement Table 1