Thromboxane Governs the Differentiation of Adipose-Derived Stromal Cells Toward Endothelial Cells In Vitro and In Vivo
Rationale: Autologous adipose-derived stromal cells (ASCs) offer great promise as angiogenic cell therapy for ischemic diseases. Due to their limited self-renewal capacity and pluripotentiality, the therapeutic efficacy of ASCs is still relatively low. Thromboxane (Tx) has been shown to play an important role in the maintenance of vascular homeostasis. However, little is known about the effects of Tx on ASC-mediated angiogenesis.
Objective: To explore the role of the Tx receptor (TP) in mediating the angiogenic capacity of ASCs in vivo.
Methods and Results:: ASCs were prepared from mouse epididymal fat pads and induced to differentiate into endothelial cells (ECs) by vascular endothelial growth factor (VEGF). Cyclooxygenase-2 (COX-2) expression, Tx production, and TP expression were upregulated in ASCs upon VEGF treatment. Genetic deletion or pharmacological inhibition of TP in mouse or human ASCs accelerated EC differentiation and increased tube formation in vitro, enhanced angiogenesis in in vivo Matrigel plugs and ischemic mouse hindlimbs. TP deficiency resulted in a significant cellular accumulation of β-catenin by suppression of calpain-mediated degradation in ASCs. Knockdown of β-catenin completely abrogated the enhanced EC differentiation of TP-deficient ASCs, while inhibition of calpain reversed the suppressed angiogenic capacity of TP re-expressed ASCs. Moreover, TP was coupled with Gαq to induce calpain-mediated suppression of β-catenin signaling through calcium influx in ASCs.
Conclusions: Tx restrained EC differentiation of ASCs through TP-mediated repression of the calpain-dependent β-catenin signaling pathway. These results indicate TP inhibition could be a promising strategy for therapy utilizing ASCs in the treatment of ischemic diseases.
- thromboxane-prostanoid receptor
- adipose-derived stromal cells
- adipose tissue
- Received October 17, 2015.
- Revision received March 2, 2016.
- Accepted March 8, 2016.