Fig. 1

Effect of culture medium differences on MSCs proliferation. A The number of MSCs cultured in Dulbecco’s modified Eagle’s medium (DMEM) with 10% fetal bovine serum (S-MSC) or serum-free medium STK2 (SF-MSC). Data are presented as means ± SD (n = 4 per group). *p < 0.05. ****P < 0.001. B Microscopic images showing proliferation of S-MSCs and SF-MSCs. Scale bar, 200 µm. C Volcano plot showing the gene expression profiles of S-MSCs and SF-MSCs (n = 3 per group). Upregulated (FC ≥ 2.0, FDR P < 0.05) and downregulated (FC ≤ − 2.0, FDR p < 0.05) differentially expressed genes (DEGs) are marked by red and blue dots, respectively. The gray dots represent insignificant DEGs. D Hierarchical clustered heatmap showing the gene expression patterns of DEGs (FC ≤ -2.0, or ≥ 2.0; P < 0.05). Each row and line represent one sample and one DEG, respectively. Red and blue colors indicate upregulation and downregulation, respectively. E In the principal component analysis (PCA), each dot represents one MSC sample. The distance between the dots indicates the level of difference between the gene expression profiles of the samples. Dots with the same color created two distinct groups (red: S-MSC and blue: SF-MSC), and the distance between the differentially colored groups was prominent. F Upregulated and downregulated terms in Gene Ontology (GO) enrichment pathway analysis when comparing SF-MSCs with S-MSCs. The terms are categorized into biological process (BP), cellular component (CC), and molecular function (MF). The y-axis shows the top 10 terms, and the x-axis shows the negative logarithm of the p value. G The significantly enriched KEGG pathways (P < 0.05) are presented. For each KEGG pathway, the bar shows fold enrichment of the pathway. The y-axis indicates the top 10 pathway categories, and the x-axis indicates the -log10 of the false discovery rate (FDR)-adjusted p value