Plasmatic Membrane Expression of Adhesion Molecules in Human Cardiac Progenitor/Stem Cells Might Explain Their Superior Cell Engraftment after Cell Transplantation

Abstract

Human bone marrow mesenchymal stem cells (BM-MSCs) and cardiac progenitor/stem cells (CPCs) have been extensively studied as a potential therapeutic treatment for myocardial infarction (MI). Previous reports suggest that lower doses of CPCs are needed to improve cardiac function relative to their bone marrow counterparts. Here, we confirmed this observations and investigated the surface protein expression profile that might explain this effect. Myocardial infarction was performed in nude rats by permanent ligation of the left coronary artery. Cardiac function and infarct size before and after cell transplantation were evaluated by echocardiography and morphometry, respectively. The CPC and BM-MSC receptome were analyzed by proteomic analysis of biotin-labeled surface proteins. Rats transplanted with CPCs showed a greater improvement in cardiac function after MI than those transplanted with BM-MSCs, and this was associated with a smaller infarct size. Analysis of the receptome of CPCs and BM-MSCs showed that gene ontology biological processes and KEGG pathways associated with adhesion mechanisms were upregulated in CPCs compared with BM-MSCs. Moreover, the membrane protein interactome in CPCs showed a strong relationship with biological processes related to cell adhesion whereas the BM-MSCs interactome was more related to immune regulation processes. We conclude that the stronger capacity of CPCs over BM-MSCs to engraft in the infarcted area is likely linked to a more pronounced cell adhesion expression program.

Figure 1

Improvement of left ventricular function in CPC-treated animals 4 weeks after transplantation. (a) Quantified values of fractional area change (FAC, %), fractional shortening (FS, %), and anterior wall thickening (AWT, %) from the control, BM-MSC, and CPC animal groups measured in 2D and M-Mode imaging 4 weeks after myocardial infarction (n = 10 in each group). (b) Representative images of heart sections from infarcted rats stained with Masson's trichrome. Fibrotic area in the left ventricle is stained in blue. (c) Quantification of the fibrotic area represented as the percentage scar tissue. (d) Quantification of the left ventricular wall (LVW) thickness in millimeters. Data are represented as mean ± SEM. ^∗p < 0.05, ^∗∗p < 0.01, and ^∗∗∗p < 0.001. (e) Detection of transplanted CPCs after transplantation in infarcted rats at different time points. Percentage of rats in which human Alu-DNA was detected in the indicated organs on days: 2 (red), 10 (green), and 21 (black) after myocardial infarction. Scale bar = 1 mm.

Figure 2

Graphical representation of upregulated GO biological processes identified by proteomic analysis in CPCs and BM-MSCs. (a) Venn diagram of data from proteomic analysis of membrane fractions, 140 proteins were expressed in CPCs, 117 were expressed in BM-MSCs, and 59 proteins were commonly expressed in both cell types. (b) Treemap diagram of biological processes overrepresented in cardiac-derived stromal cells using REVIGO webtool after proteomic analysis. (c) Dotplot representing GO biological processes overrepresented in CPCs. (d) Treemap diagram of biological processes significantly overrepresented in bone marrow mesenchymal stem cells using REVIGO webtool after proteomic analysis. (e) Dotplot representing GO biological processes significantly overrepresented in BM-MSCs.

Figure 3

Graphical representation of CPC (a) and BM-MSC (b) interaction networks based on proteomics data sets.