Aims: Shear stress-induced apoptosis is one of the leading problems in seeding cells of tissue-engineered blood vessels (TEBVs). We aim to determine the human bone mesenchymal stem cell (hBMSC) apoptosis under shear stress and its possible mechanism.
Main methods: hBMSCs were subjected to 3-, 10-, and 30-dyn/cm(2) shear stress in vitro. Cell multiplication and apoptosis were analyzed by flow cytometry. Apoptosis-related genes were screened by a microarray and evidenced by real-time polymerase chain reaction (RT-PCR). hBMSCs were treated with the human recombinant cell inhibitor of apoptosis protein 1 (cIAP1) and its inhibitor, direct IAP-binding protein with low pl (DIABLO), and then cell apoptosis was analyzed.
Key findings: Exposure to shear stress (3dyn/cm(2) for >6h) activated apoptosis progress of hBMSCs. However, the same degree of shear stress (3dyn/cm(2) for 6h) did not induce apoptosis. Microarray screening and RT-PCR revealed that Bcl-2-related ovarian killer (BOK) and apoptotic protease-activating factor 1 (APAF1), key molecules of the mitochondrial apoptosis pathway, were markedly upregulated under 3-dyn/cm(2) shear stress. Then, we observed that cIAP1, a Caspase 9 inhibitor, was elevated under 3dyn/cm(2) at short-time exposure (2 or 6h), and it was reduced at long-time exposure (24h). When treated with human recombinant cIAP1, Caspase 3 activity and LDH release of hBMSCs were decreased, and vice versa when treated with DIABLO.
Significance: cIAP1 attenuates hBMSC apoptosis when cells were exposed to shear stress through the regulation of the BOK-APAF1-Caspase 9-Caspase 3 pathway. It may present a pharmacological target to enhance hBMSC biological function in the application of TEBVs.
Keywords: Bone mesenchymal stem cells; Inhibitor of apoptosis protein; Microarray; Mitochondrial apoptosis; Shear stress.
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