The effect of bone marrow microenvironment on the functional properties of the therapeutic bone marrow-derived cells in patients with acute myocardial infarction.

BACKGROUND: Treatment of acute myocardial infarction with stem cell transplantation has achieved beneficial effects in many clinical trials. The bone marrow microenvironment of ST-elevation myocardial infarction (STEMI) patients has never been studied even though myocardial infarction is known to cause an imbalance in the acid-base status of these patients. The aim of this study was to assess if the blood gas levels in the bone marrow of STEMI patients affect the characteristics of the bone marrow cells (BMCs) and, furthermore, do they influence the change in cardiac function after autologous BMC transplantation. The arterial, venous and bone marrow blood gas concentrations were also compared. METHODS: Blood gas analysis of the bone marrow aspirate and peripheral blood was performed for 27 STEMI patients receiving autologous stem cell therapy after percutaneous coronary intervention. Cells from the bone marrow aspirate were further cultured and the bone marrow mesenchymal stem cell (MSC) proliferation rate was determined by MTT assay and the MSC osteogenic differentiation capacity by alkaline phosphatase (ALP) activity assay. All the patients underwent a 2D-echocardiography at baseline and 4 months after STEMI. RESULTS: As expected, the levels of pO(2), pCO(2), base excess and HCO(3) were similar in venous blood and bone marrow. Surprisingly, bone marrow showed significantly lower pH and Na(+) and elevated K(+) levels compared to arterial and venous blood. There was a positive correlation between the bone marrow pCO(2) and HCO(3) levels and MSC osteogenic differentiation capacity. In contrast, bone marrow pCO(2) and HCO(3) levels displayed a negative correlation with the proliferation rate of MSCs. Patients with the HCO(3) level below the median value exhibited a more marked change in LVEF after BMC treatment than patients with HCO(3) level above the median (11.13 ± 8.07% vs. 2.67 ± 11.89%, P = 0.014). CONCLUSIONS: Low bone marrow pCO(2) and HCO(3) levels may represent the optimal environment for BMCs in terms of their efficacy in autologous stem cell therapy in STEMI patients.

Tumor necrosis factor alpha promotes the expression of immunosuppressive proteins and enhances the cell growth in a human bone marrow-derived stem cell culture.

Mesenchymal stem cells (MSCs) are widely used in experimental treatments for various conditions that involve normal tissue regeneration via inflammatory repair. It is known that MSCs can secrete multiple soluble factors and suppress inflammation. Even though the effect of MSCs on inflammation has been extensively studied, the effect of inflammation on MSCs is poorly understood. One of the major cytokines released at the site of inflammation is tumor necrosis factor alpha (TNF-α) which is known to induce MSC invasion and proliferation. Therefore, we wanted to test the effects of TNF-α exposure on MSCs derived from human bone marrow. We found, as expected, that cell proliferation was significantly enhanced during TNF-α exposure. However, according to the cell surface marker analysis, the intensity of several antigens in the minimum criteria panel for MSCs proposed by International Society of Cellular Therapy (ISCT) was decreased dramatically, and in certain cases, the criteria for MSCs were not fulfilled. In addition, TNF-α exposure resulted in a significant but transient increase in human leukocyte antigen and CD54 expression. Additional proteomic analysis by two-dimensional difference gel electrophoresis and mass spectrometry revealed three proteins whose expression levels decreased and 8 proteins whose expression levels increased significantly during TNF-α exposure. The majority of these proteins could be linked to immunosuppressive and signalling pathways. These results strongly support reactive and immunosuppressive activation of MSCs during TNF-α exposure, which might influence MSC differentiation stage and capacity.