In the field of bone regeneration, BMP-2 is considered one of the most important growth factors because of its strong osteogenic activity, and is therefore extensively used in clinical practice. However, the short half-life of BMP-2 protein necessitates the use of supraphysiological doses, leading to severe side-effects. This study investigated the efficiency of bone formation at ectopic and orthotopic sites as a result of a low-cost, prolonged presence of BMP-2 in a large animal model. Constructs consisting of alginate hydrogel and BMP-2 cDNA, together acting as a non-viral gene-activated matrix, were combined with goat multipotent stromal cells (gMSCs) and implanted in spinal cassettes or, together with ceramic granules, intramuscularly in goats, both for 16 weeks. Bone formation occurred in all cell-seeded ectopic constructs, but the constructs containing both gMSCs and BMP-2 plasmid DNA showed higher collagen I and bone levels, indicating an osteogenic effect of the BMP-2 plasmid DNA. This was not seen in unseeded constructs, even though transfected, BMP-2-producing cells were detected in all constructs containing plasmid DNA. Orthotopic constructs showed mainly bone formation in the unseeded groups. Besides bone, calcified alginate was present in these groups, acting as a surface for new bone formation. In conclusion, transfection of seeded or resident cells from this DNA delivery system led to stable expression of BMP-2 during 16 weeks, and promoted osteogenic differentiation and subsequent bone formation in cell-seeded constructs at an ectopic location and in cell-free constructs at an orthotopic location in a large animal model.

Abstract-Geometric remodeling in de novo atherosclerosis and in restenosis after balloon angioplasty constitutes a change in total arterial circumference that, together with plaque growth or neointima formation, determines the lumen of the artery. The heterogeneous nature of arterial obstructions raises the question of whether early and late outcomes (restenosis) of angioplasty are affected by the degree and direction of de novo atherosclerotic remodeling. This study was designed to assess the relationship between atherosclerotic remodeling and the degree and mechanism of restenosis after balloon angioplasty. Atherosclerosis was induced in 27 peripheral arteries of 18 Yucatan micropigs by a combination of denudation and atherogenic diet. Balloon angioplasty was performed, with serial intravascular ultrasound and quantitative angiography before and after intervention and at 42 days' follow-up. We used the relative media-bounded area (MBA), defined as the MBA of the treated site divided by the MBA of the reference, before angioplasty as a measure of remodeling in de novo atherosclerosis and late MBA loss as a measure of remodeling after balloon angioplasty. Relative MBA before angioplasty was not correlated with angiographic and echographic acute gain after balloon angioplasty (rϭ. Key Words: remodeling Ⅲ intravascular ultrasound Ⅲ balloon angioplasty Ⅲ atherosclerosis Ⅲ restenosis G eometric remodeling in de novo atherosclerosis 1-4 and in restenosis after balloon angioplasty 5-9 constitutes a change in total arterial circumference that, together with plaque growth or neointima formation, determines the lumen of the artery. The change in total arterial circumference ranges from enlargement, which may lead to an actual increase in lumen size, to shrinkage. In the latter case, remodeling contributes to luminal (re)narrowing. The different contributions of remodeling and plaque formation to the atherosclerotic process result in a heterogeneity of atherosclerotic arterial obstructions, with a large plaque mass accommodated by a locally enlarged artery at one extreme and a small plaque in a focally shrunken artery at the other. The heterogeneous nature of arterial obstructions with respect to remodeling raises the question of whether early and late outcomes (restenosis) of angioplasty are affected by the degree and direction of de novo atherosclerotic remodeling and whether, for instance, a lesion based predominantly on shrinkage will restenose by remodeling rather than by neointima formation.In a recent serial IVUS study from our laboratory in human femoral arteries, 10 we observed no difference in acute lumen gain between three categories of de novo atherosclerotic remodeling, ie, enlarged, unchanged, and shrunken arteries. However, the mechanism of acute gain by balloon angioplasty was different, showing more plaque reduction or axial redistribution of plaque in enlarged arteries and more stretch of the arterial wall (increase in MBA) in shrunken arteries.Restenosis is the arithmetic sum of neointima formation, [11...

Bone morphogenetic protein-2 (BMP-2) gene delivery has shown to induce bone formation in vivo in cell-based tissue engineering. In addition, the chemoattractant stromal cell-derived factor-1α (SDF-1α, also known as CXCL12) is known to recruit multipotent stromal cells towards its release site where it enhances vascularisation and possibly contributes to osteogenic differentiation. To investigate potential cooperative behaviour for bone formation, we investigated combined release of BMP-2 and SDF-1α on ectopic bone formation in mice. Multipotent stromal cellseeded and cell-free constructs with BMP-2 plasmid DNA and /or SDF-1α loaded onto gelatin microparticles, were implanted subcutaneously in mice for a period of 6 weeks. Histological analysis and histomorphometry revealed that the onset of bone formation and the formed bone volume were both enhanced by the combination of BMP-2 and SDF-1α compared to controls in cell-seeded constructs. Samples without seeded multipotent stromal cells failed to induce any bone formation.We conclude that the addition of stromal cellderived factor-1α to a cell-seeded alginate based bone morphogenetic protein-2 plasmid DNA construct has an additive effect on bone formation and can be considered a promising combination for bone regeneration.

The amount of plaque present before stent placement was a determinant of the amount of intimal hyperplasia present after stent placement.