Human umbilical cord mesenchymal stem cells reduce platelet α-granule release in rats via the AKT/MEK/ERK pathway during acute exposure to high-altitude hypoxia

Figure 1 Isolation, culture, identification, and induced differentiation of human umbilical cord mesenchymal stem cells. A: On day 15 of primary cell culture, human umbilical cord mesenchymal stem cells exhibited robust growth and over 90% confluence (magnification 100 ×); B: Identification of human umbilical cord mesenchymal stem cell surface antigens by flow cytometry; C: Induction of chondroblastic differentiation for three weeks resulted in the appearance of chondrocytes that stained blue with Alcian Blue (magnification 50 ×); D: Induction of adipogenic differentiation for two weeks resulted in the appearance of lipid droplets that stained red with Oil Red O (magnification 200 ×); E: Induction of osteogenic differentiation for three weeks led to the appearance of calcium nodules that stained red with Alizarin Red (magnification 100 ×).

Figure 2 Transmission electron microscopy images of platelets in the different groups. A: Platelet morphology in the low-altitude group; B: Platelet morphology in the high-altitude group; C: Platelet morphology in the human umbilical cord mesenchymal stem cell group.

Figure 3 Expression levels of von Willebrand factor, platelet factor 4, and beta-thromboglobulin. A: Expression of von Willebrand factor in the different groups; B: Expression of platelet factor 4 in the different groups; C: Expression of beta-thromboglobulin in the different groups. n = 8 in each group. ^aP < 0.05, ^bP < 0.01, ^cP < 0.001, ^dP < 0.0001. vWF: von Willebrand factor; hUC-MSC: Human umbilical cord mesenchymal stem cell; PF4: Platelet factor 4; β-TG: Beta-thromboglobulin.

Figure 4 Expression of CD62p on platelet surfaces, as shown by flow cytometry. A: The expression rate of CD62p in the low-altitude group was 14.3%; B: The expression rate of CD62p in the high-altitude group was 20.1%; C: The expression rate of CD62p in the human umbilical cord mesenchymal stem cell group was 14.4%; D: The expression rate of CD62p in low-altitude group, high-altitude group, and human umbilical cord mesenchymal stem cell group. n = 8 in each group. ^dP < 0.0001. hUC-MSC: Human umbilical cord mesenchymal stem cell.

Figure 5 Human umbilical cord mesenchymal stem cells reduce the release of platelet α-granules in rats exposed to acute high-altitude hypoxia via the protein kinase B/mitogen-activated protein kinase/extracellular-signal regulated kinase pathway. A: Expression of p-protein kinase B in the different groups; B: Expression of p-mitogen-activated protein kinase in the different groups; C: Expression of p-extracellular-signal regulated kinase in the different groups. ^aP < 0.05, ^bP < 0.01, ^cP < 0.001. AKT: Protein kinase B; MEK: Mitogen-activated protein kinase; ERK: Extracellular-signal regulated kinase; hUC-MSC: Human umbilical cord mesenchymal stem cell.