Papers by Keyword: Smooth Muscle Cells

Abstract: Small caliber vascular replacement (<4 mm) still remains a challenge for medical and research teams, as no available vascular substitutes (VS) are suitable for small diameter bypass. Vascular engineering proposes new models of small diameter VS but rare are those that meet the biocompatibility and mechanical criteria. In this study, we developed a new scaffold made by the combination of two natural biomacromolecules: collagen and silk fibroin. The scaffold was further cellularised with porcine smooth muscle cells. First, the behavior of cells in the collagen-fibroin constructs was verified in order to evaluate the biocompatibility of the scaffold with the cells. Then, gel mass loss and cellular attachment, morphology, spreading and viability were analysed. The results showed an excellent interaction and biocompatibility between collagen, silk fibroin fibers and cells. Thus, the collagen-fibroin construct appears to be a very attractive material for vascular tissue engineering.

Abstract: Diseases occurring to blood vessel are preferentially solved by replacing the vessel by an autologous graft. When it is not available, a synthetic graft is used which has low patency rates for small diameter (<6 mm) vessels. Tissue engineering of blood vessel aims to improve the performance of vascular substitutes. Bioreactors are used in vascular tissue engineering to mimic the mechanical and biochemical environment of blood vessel. A 2D bioreactor was custom made in order to impose a dynamical strain to silicone membrane receiving the collagen cell-based construct. Collagen gels with vascular smooth muscle cells cultured inside were subdued to maturation under dynamical uniaxial stretch regimes at 1Hz for 48 hours. The percentage of deformation encountered by the silicone membrane was measured by ImageJ. Collagen fibrils and porcine smooth muscle cells (PSMC) orientations were assessed by scanning electron microscopy (SEM). Results show that the study of mechanical conditioning on cell activity is an important issue for enhancing the alignment of collagen fibrils.

Abstract: Porosity and pore size are needed for successful cell seeding and proliferation into porous scaffolds. This study was focused on a hydrogel-seeding method to improve cell adhesion and proliferation in tubular porous scaffolds for vascular grafts application. Tubular scaffolds were fabricated from a biodegradable elastic polymer, poly(L-lactide-co-ε-caprolactone) (PLCL) (50:50, Mn 1.58×105), by an extrusion-particulate leaching method. Vascular smooth muscle cells (VSMCs) were dispersed in collagen hydrogel and then seeded into the tubular PLCL scaffolds having various pore sizes, 50-100 μm, 100-200 μm, and 300-500 μm, respectively. As a result, the efficiency of cell adhesion and proliferation was dependent on the pore size of the scaffolds. Especially, the cell proliferation efficiency was improved by using the hydrogel-seeding method as compared with by using a previously established method. In summary, this study demonstrates that the efficiency of cell adhesion and proliferation was dependent on the pore size of the scaffolds in the hydrogel-seeding method.

Abstract: Macrophages play a critical role in inflammatory response to implanted biomaterials and formation of restenosis. Macrophage adhesion may lead to macrophage activation and smooth muscle cell proliferation. Titanium oxide films on stainless steel are potential biomaterials for application to vascular stents. They have different influences on smooth muscle cell proliferation in in vivo tests, which could be the main reason for restenosis, but the mechanism is not clear. In this study we show that titanium oxide films can reduce inflammatory reaction with macrophages. Unstimulated macrophages release small amounts of chemical substance such as NO and give slight effect on smooth muscle cell proliferation.

Abstract: Poly (D,L-latic-co-glycolic acid) (PLGA) has been used as the artificial scaffold for blood vessel formation. In order to hinder smooth muscle cell (SMC) angiogenesis, new scaffold design method of loading Epigallocatechin 3-O-gallate (EGCG) on PLGA film was introduced. PLGA and EGCG were dissolved in acetone and film-shape scaffold was manufactured. Antiangiogenetic effect of EGCG released on scaffold was analyzed for SMC and human umbilical vein endothelial cell (HUVEC) and method for selective inhibition from the difference of growth of SMC and HUVEC was suggested.

Abstract: Clinical applications of expanded polytetrafluoroethylene (ePTFE) as a small diameter graft have been limited due to its limited patency rates, even though its demands are high. After fabricating the biodegradable PLGA layers on both the inside and outside of ePTFE, long-term in vitro smooth muscle cell culture was performed on the luminal scaffold surface. The fabricated hybrid ePTFE scaffolds were designed to have three distinctive layers and porous structures in the biodegradable layers generated by gas-foaming of the ammonium bicarbonate porogens, i.e. two layers of poly(lactide-co-glycolide) (PLGA) as biodegradable layers for tissue engineering and an ePTFE layer in the middle as a non-biodegradable layer. We evaluated the regenerated vascular tissues after applying either static or pulstile flow on a smooth muscle cells-seeded hybrid scaffold. Analysis of the engineered tissues was performed with SEM for morphological observation and H&E staining for observation of tissue development dependent upon a mode of culture system, flow patterns and scaffold species.

Abstract: Collagen is the most used naturally occurring scaffold material. It’s a structural protein ubiquitous among mammalian. The ability of collagen type I to host different cell phenotype in vitro and its low antigenecity in vivo are well known. However, the principal drawback of collagenbased materials consists in their low mechanical properties. For vascular tissue engineering this represents a major limit, as the aim is to mimic the structure of a native vessel, which is known to be resistant and viscoelastic. Moreover, vascular cells are known to be susceptible in vivo to reorganize the matrix in which they proliferate. Therefore, the aim of this project is to study the micro structural organization of collagen-based scaffolds, and to assess the interactions between collagen and smooth muscle cells during regeneration. This knowledge will then allow the development of appropriate strategies to tailor the microstructure of the scaffold and its properties. Smooth muscle cells (SMCs) were selected to study the interactions between cells and matrix during the proliferation. Atomic Force Microscopy (AFM) in dry state in tapping mode and Confocal Laser Scanning Microscopy (CLSM) in reflection mode were used to investigate the microstructure of the scaffold. For the former technique cells were seeded on top of the collagen gel after jellification, while for the latter, cells were embedded into the collagen gel and stained with Rhodamine. The contact points between matrix and cells were investigated, as well as the capacity of vascular cells to induce a structural reorganization of collagen fibrils in the scaffold.

Abstract: A variety of attempts have been made to improve small diameter expanded polytetrafluoroethylene (ePTFE) vascular grafts through cellular and tissue engineering. Some of these techniques have made their way into clinical trials. Coating of endothelial cells via surface modifications has increased graft patency in some hands but lack of firm adhesion of the seeded cells on the graft surface can lead to graft failures. We increased cell-graft and graft-tissue interactions by inducing smooth muscle cell growth into the pores of the graft wall through chemical modification of superficial surfaces, including those of the transmural pores. In contrast to non-modified surfaces seeded cells adhered on and proliferated into the modified pores and internodal surfaces. Cellular growth into these critical pores spaces seemed to arise from surface modification including defluorination and oxygenation incorporation leading to changes in chemical composition, surface tension, cell-surface interaction and modified surface fibril aggregation.

Abstract: The biocompatibility of the NiTi alloy self-expanding stent, its dilating effect on the vascular wall, and the apoptosis of smooth muscle cells (SMCs) were studied by implantation of stent into the rabbit’s abdominal aorta for different period. All the animals lived throughout the study. There was no detectable migration or dissection of the stent, and there were no acute closures or sub-acute thromboses in the vessels. The rates of patency were 100% both at the beginning when the stent was implanted and at the end when the animal was sacrificed. It may be concluded that the vascular intima covers the whole stent at the 8-week point. The atherosclerotic process existed in the vascular intima in contact with the stent surface, while the proliferation and apoptosis of SMCs occured simultaneously. After stent implantation, the apoptosis happened in both intima and media, which indicated that the stent might not only stimulate the intima but also compress the media, leading to proliferation and apoptosis. This might contribute to vessel remodeling after stenting.

Abstract: The feasibility of using an alternating magnetic field from induction heating furnace to heat the NiTi stent and the influence of hyperthermic on smooth muscle cells (SMCs) have been studied in the present work. The electromagnetic field is capable of significantly heating NiTi stents and the heating temperature can be adjusted by changing the voltage and heating time of the furnace and the position of NiTi stents. The shape and living status of SMCs were influenced by the heat treatment procedures. There were three stages of SMCs reaction to heat: (1) when the temperature below 44°C, the living status was not changed; (2) between 44°C to 50°C, the cells shrinked and were less dyed with trypan blue, which indicated that they were still alive; (3) when the temperature was above the 50°C, all the cells died. It was found that from 44°C to 50°C, the SMCs died in apoptosis, which might allow us to heat the implanted stent to prevent restenosis.