RESUMO
Dental pulp stem cells (DPSCs) have previously demonstrated potential pericyte-like topography and function. However, the mechanisms regulating their pericyte function are still unknown. In this study, murine DPSC angiogenic and pericyte function were investigated. Tie2-GFP mouse DPSCs were negative for GFP, indicating the absence of endothelial cells in DPSC cultures. Endothelial cells co-cultured with DPSCs formed more mature in vitro tube-like structures as compared with those co-cultured with bone marrow stromal cells (BMSCs). Many DPSCs were located adjacent to vascular tubes, assuming a pericyte location. Subcutaneous DPSC transplants in mice with matrigel (MG) (DPSC-MG) induced more vessel formation than BMSC-MG. Soluble Flt (sFlt), an angiogenic inhibitor that binds VEGF-A, significantly decreased the amount of blood vessels in DPSC-MG, but not in BMSC-MG. sFlt inhibited VEGFR2 and downstream ERK signaling in DPSCs. Similar to sFlt inhibition, VEGFR2 knockdown in DPSCs resulted in down-regulation of Vegfa, Vegf receptors, and EphrinB2 and decreased angiogenic induction of DPSCs in vivo. Therefore, the capacity of DPSCs to induce angiogenesis is VEGFR2-dependent. DPSCs enhance angiogenesis by secreting VEGF ligands and associating with vessels resembling pericyte-like cells. This study provides first insights into the mechanism(s) of DPSC angiogenic induction and their function as pericytes, crucial aspects for DPSC use in tissue regeneration.
Assuntos
Polpa Dentária/citologia , Neovascularização Fisiológica/fisiologia , Pericitos/fisiologia , Células-Tronco/fisiologia , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/fisiologia , Inibidores da Angiogênese/farmacologia , Animais , Vasos Sanguíneos/efeitos dos fármacos , Técnicas de Cultura de Células , Técnicas de Cocultura , Colágeno , Combinação de Medicamentos , Células Endoteliais/fisiologia , Efrina-B2/efeitos dos fármacos , Matriz Extracelular , Humanos , Laminina , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Células-Tronco Mesenquimais/fisiologia , Mesoderma/citologia , Camundongos , Músculo Esquelético/cirurgia , Neovascularização Fisiológica/efeitos dos fármacos , Pericitos/efeitos dos fármacos , Proteoglicanas , Receptores Proteína Tirosina Quinases/análise , Receptor TIE-2 , Receptores de Fatores de Crescimento do Endotélio Vascular/efeitos dos fármacos , Transplante de Células-Tronco , Alicerces Teciduais , Fator A de Crescimento do Endotélio Vascular/efeitos dos fármacos , Receptor 1 de Fatores de Crescimento do Endotélio Vascular/farmacologia , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/antagonistas & inibidoresRESUMO
BACKGROUND: Processes of restenosis, following arterial injury, are complex involving different cell types producing various cytokines and enzymes. Among those enzymes, smooth muscle cell-derived matrix metalloproteinases (MMPs) are thought to take part in cell migration, degrading of extracellular matrix, and neointima formation. MMP-9, also known as gelatinase B, is expressed immediately after vascular injury and its expression and activity can be inhibited by statins. Using an established in vivo model of vascular injury, we investigated the effect of the HMG-CoA reductase inhibitor rosuvastatin on MMP-9 expression and neointima formation. MATERIALS AND METHODS: 14-week old male Sprague Dawley rats underwent balloon injury of the common carotid artery. Half of the animals received rosuvastatin (20 mg/kg body weight/day) via oral gavage, beginning 3 days prior to injury. Gelatinase activity and neointima formation were analyzed 3 days and 14 days after balloon injury, respectively. 14 days after vascular injury, proliferative activity was assessed by staining for Ki67. RESULTS: After 14 days, animals in the rosuvastatin group showed a decrease in total neointima formation (0.194±0.01 mm2 versus 0.124±0.02 mm2, p<0.05) as well as a reduced intima/media ratio (1.26±0.1 versus 0.75±0.09, p<0.05). Balloon injury resulted in increased activity of MMP-9 3 days after intervention for both rosuvastatin treated animals and controls with no significant difference observed between the groups. There was a trend towards a reduction in the number of Ki67-positive cells 14 days after injury. CONCLUSIONS: Rosuvastatin attenuates neointima formation without affecting early MMP-9 activity in a rat model of vascular injury.
