Diyabetik Yara Tedavisinde Kullanılmak Üzere Nanopartiküler Statin ve Kök Hücre İçeren Doku İskelelerinin Formülasyonu ve İn Vitro/İn Vivo Değerlendirilmesi
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Simvastatin has been shown to support wound healing and stem cell treatment efficacy independent of cholesterol-lowering mechanism in recent studies. Under the light of these facts, in order to provide a new treatment approach in diabetic wound care, novel three dimensional and biodegradable wound healing system has been formulated by preparing tissue scaffolds consisting of biological polimers, simvastatin loaded nanostructured lipid carriers (NLCs) and mesenchimal stem cells. NLC formulations containing simvastatin at the concentrations of 10% or 20% of lipid phase were prepared by high pressure homogenization technique at 50:50 or 70:30 liquid:solid lipid ratio. Precirol ATO 5 as solid lipid, Maisine as liquid lipid, Tween 80 as hydrophilic surfacactant and Lipoid S100 as lipophilic surfactant were used in the formulations. Simvastatin loaded NLC formulations are prepared having 158 nm particle size, homogeneous spherical particles with PDI values below 0.17 and encapsulation efficiency above 99%. As a result of in vitro release studies, release of simvastatin from the NLC formulations has been characterized by a high burst release tendency that was followed by a slow release rate and finally reaching plateau at about 12-24 hours. In stability studies carried out at 25°C and 4°C, the formulations were found to maintain monodisperse distributions below 200 nm for 90 days at 4°C and simvastatin was observed to be stable for 15 days at 4°C. Tissue scaffold formulations containing simvastatin loaded NLCs were prepared by freeze drying method in a combination of 1:1 or 2:1 chitosan:collagen polymers with unconcentrated or 2-fold concentrated NLC formulations. The cross-linked tissue scaffold formulation prepared with 2:1 chitosan:collagen polymer ratio and 2-fold concentrated NLC formulation, having a three-dimensional high porous structure with a porosity value of 74.38% and sufficient large pore size distribution from 20 μm to 200 μm and with 710.88% high water absorption capacity, 57.7% low weight loss and good mechanical strength was found to be suitable for in vivo studies. Incorporation of NLCs into tissue scaffolds decreased the initial simvastatin burst release ratio and maintained a more controlled release profile. Cytotoxic effect of tissue scaffolds was not observed on L929 mouse fibroblast cells in cell culture studies. In vivo studies have indicated that tissue scaffolds containing simvastatin lipid nanoparticles increased wound closure rate and promoted the vascularization of injured tissue when compared to control groups. In pathological investigations, simvastatin has been shown to enhance viability and proliferation of stem cells. Thereupon, tissue scaffold formulation containing simvastatin lipid nanoparticles and stem cells together provided effective wound healing with increased epithelialization, proliferation and vascularization.