Controlled release of vascular endothelial growth factor from spray-dried alginate microparticles in collagen-hydroxyapatite scaffolds for promoting vascularization and bone repair

2015 ◽  
Vol 11 (4) ◽  
pp. 1097-1109 ◽  
Author(s):  
Elaine Quinlan ◽  
Adolfo López-Noriega ◽  
Emmet M. Thompson ◽  
Alan Hibbitts ◽  
Sally Ann Cryan ◽  
...  
Keyword(s):  
Vascular Endothelial Growth Factor ◽  
Controlled Release ◽  
Growth Factor ◽  
Bone Repair ◽  
Vascular Endothelial ◽  
Endothelial Growth Factor ◽  
Spray Dried

scholarly journals Local, Controlled Release In Vivo of Vascular Endothelial Growth Factor Within a Subcutaneous Scaffolded Islet Implant Reduces Early Islet Necrosis and Improves Performance of the Graft

2018 ◽  
Vol 27 (3) ◽  
pp. 531-541 ◽  
Author(s):  
John A. Gebe ◽  
Anton Preisinger ◽  
Michel D. Gooden ◽  
Leonard A. D’Amico ◽  
Robert B. Vernon
Keyword(s):  
Vascular Endothelial Growth Factor ◽  
Controlled Release ◽  
Growth Factor ◽  
Islet Transplantation ◽  
Implant Design ◽  
Vascular Endothelial ◽  
Test Bed ◽  
Endothelial Growth Factor ◽  
Implant Test

Islet transplantation remains the only alternative to daily insulin therapy for control of type 1 diabetes (T1D) in humans. To avoid the drawbacks of intrahepatic islet transplantation, we are developing a scaffolded islet implant to transplant islets into nonhepatic sites. The implant test bed, sized for mice, consists of a limited (2-mm) thickness, large-pore polymeric sponge scaffold perforated with peripheral cavities that contain islets suspended in a collagen hydrogel. A central cavity in the scaffold holds a 2-mm diameter alginate sphere for controlled release of the angiogenic cytokine vascular endothelial growth factor ( VEGF). Host microvessels readily penetrate the scaffold and collagen gel to vascularize the islets. Here, we evaluate the performance of the implant in a subcutaneous (SC) graft site. Implants incorporating 500 syngeneic islets reversed streptozotocin-induced diabetes in mice approximately 30 d after SC placement. Controlled release of a modest quantity (20 ng) of VEGF within the implant significantly reduced the time to normoglycemia compared to control implants lacking VEGF. Investigation of underlying causes for this effect revealed that inclusion of 20 ng of VEGF in the implants significantly reduced central necrosis of islets 24 h after grafting and increased implant vascularization (measured 12 d after grafting). Collectively, our results demonstrate (1) that the scaffolded islet implant design can reverse diabetes in SC sites in the absence of prevascularization of the graft site and (2) that relatively low quantities of VEGF, delivered by controlled release within the implant, can be a useful approach to limit islet stress after grafting.

Adenovirus-mediated expression of vascular endothelial growth factor-a potentiates bone morphogenetic protein9-induced osteogenic differentiation and bone formation

2016 ◽  
Vol 397 (8) ◽  
pp. 765-775 ◽  
Author(s):  
Chang-jun Pi ◽  
Kai-lu Liang ◽  
Zhen-yong Ke ◽  
Fu Chen ◽  
Yun Cheng ◽  
...  
Keyword(s):  
Vascular Endothelial Growth Factor ◽  
Growth Factor ◽  
Bone Formation ◽  
Osteogenic Differentiation ◽  
Bone Repair ◽  
Osteoporotic Fractures ◽  
Angiogenic Factor ◽  
Vascular Endothelial ◽  
Akt Inhibitor ◽  
Endothelial Growth Factor

Abstract Mesenchymal stem cells (MSCs) are suitable seed cells for bone tissue engineering because they can self-renew and undergo differentiation into osteogenic, adipogenic, chondrogenic, or myogenic lineages. Vascular endothelial growth factor-a (VEGF-a), an angiogenic factor, is also involved in osteogenesis and bone repair. However, the effects of VEGF-a on osteogenic MSCs differentiation remain unknown. It was previously reported that bone morphogenetic protein9 (BMP9) is one of the most important osteogenic BMPs. Here, we investigated the effects of VEGF-a on BMP9-induced osteogenesis with mouse embryo fibroblasts (MEFs). We found that endogenous VEGF-a expression was undetectable in MSCs. Adenovirus-mediated expression of VEGF-a in MEFs potentiated BMP9-induced early and late osteogenic markers, including alkaline phosphatase (ALP), osteocalcin (OCN), and osteopontin (OPN). In stem cell implantation assays, VEGF-a augmented BMP9-induced ectopic bone formation. VEGF-a in combination with BMP9 effectively increased the bone volume and osteogenic activity. However, the synergistic effect was efficiently abolished by the phosphoinositide 3-kinase (PI3K)/AKT inhibitor LY294002. These results demonstrated that BMP9 may crosstalk with VEGF-a through the PI3K/AKT signaling pathway to induce osteogenic differentiation in MEFs. Thus, our findings demonstrate the effects of VEGF-a on BMP9-induced bone formation and provide a new potential strategy for treating nonunion fractures, large segmental bony defects, and/or osteoporotic fractures.

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