Assessment of electromechanically stimulated bone marrow stem cells seeded acellular cardiac patch in a rat myocardial infarct model.

In this study, we evaluated cardiomyogenic differentiation of electromechanically stimulated rat bone marrow-derived stem cells (rt-BMSCs) on an acellular bovine pericardium (aBP) and we looked at the functioning of this engineered patch in a rat myocardial infarct (MI) model. aBP was prepared using a detergent-based decellularization procedure followed by rt-BMSCs seeding, and electrical, mechanical, or electromechanical stimulations (3 millisecond pulses of 5 V cm-1at 1 Hz, 5% stretching) to enhance cardiomyogenic differentiation. Furthermore, the electromechanically stimulated patch was applied to the MI region over 3 weeks. After this period, the retrieved patch and infarct region were evaluated for the presence of calcification, inflammatory reaction (CD68), patch to host tissue cell migration, and structural sarcomere protein expressions. In conjunction with any sign of calcification, a higher number of BrdU-labelled cells, and a low level of CD68 positive cells were observed in the infarct region under electromechanically stimulated conditions compared with static conditions. More importantly, MHC, SAC, Troponin T, and N-cad positive cells were observed in both infarct region, and retrieved engineered patch after 3 weeks. In a clear alignment with other results, our developed acellular patch promoted the expression of cardiomyogenic differentiation factors under electromechanical stimulation. Our engineered patch showed a successful integration with the host tissue followed by the cell migration to the infarct region.

Polyethyleneimine brushes effectively inhibit encrustation on polyurethane ureteral stents both in dynamic bioreactor and in vivo.

Polyurethane (PU) ureteral stents have been widely used as biomedical devices to aid the flow of the urine. Due to the biofilm formation and encrustation complications it has been hindered their long term clinical usage. To overcome these complications, in this study, cationic polyethyleneimine (PEI) brushes grafted on PU stents and their performances were tested both in a dynamic biofilm reactor system (in vitro) and in a rat model (in vivo). Thus, we hypothesized that PEI brushes inhibit bacterial adhesion owing to the dynamic motion of brushes in liquid environment. In addition, cationic structure of PEI disrupts the membrane and so kills the bacteria on time of contact. Cationic PEI brushes decreased the biofilm formation up to 2 orders of magnitude and approximately 50% of encrustation amount in respect to unmodified PU, in vitro. In addition, according to Atomic Absorption Spectroscopy (AAS) results, approximately 90% of encrustation was inhibited on in vivo animal models. Decrease in encrustation was clearly observed on the stents obtained from rat model, by Scanning Electron Microscopy (SEM). Also, histological evaluations showed that; PEI brush grafting decreased host tissue inflammation in close relation to decrease in biofilm formation and encrustation. As a results; dual effect of anti-adhesive and contact-killing antibacterial strategy showed high efficiency on PEI brushes grafted PU stents both in vitro and in vivo.

Characterization and evaluation of triamcinolone, raloxifene, and their dual-loaded microspheres as prospective local treatment system in rheumatic rat joints.

In this study, injectable microspheres were developed for the local treatment of joint degeneration in rheumatoid arthritis (RA). Microspheres loaded with triamcinolone (TA), a corticosteroid drug, and/or raloxifene (Ral), a cartilage regenerative drug, were prepared with a biodegradable and biocompatible polymer, polycaprolactone (PCL). Microspheres were optimized for particle size, structural properties, drug release, and loading properties. In vitro release of Ral was very slow because of the low solubility of the drug and hydrophobic nature of PCL. However, when coloaded with TA, both drugs were released at higher amounts compared with their single forms. Smallest particle sizes were obtained in dual drug-loaded microspheres. In vitro cytotoxicity tests showed biocompatibility of microspheres. In vivo bioefficacy of these microspheres was also examined in adjuvant-induced arthritis model in rats. In vivo histological studies of control groups showed development of RA with high median lesion score (5.0). Compared with control and intra-articular free drug injections, microsphere treatment groups showed lower lesion scores and better healing outcomes in histological evaluations. Results suggest that a controlled delivery system of TA and RAL by a single injection in inflamed joints holds promise for healing and suppressing inflammation.

Brain targeting of Atorvastatin loaded amphiphilic PLGA-b-PEG nanoparticles.

The objective of this study was to develop polysorbate 80 coated and Atorvastatin loaded poly(lactic-co-glycolic acid)-block-poly(ethylene glycol) (PLGA-b-PEG) nanoparticles and to investigate advantages of coating on nanoparticles for brain delivery of Atorvastatin. The nanoparticles were prepared by nanoprecipitation method. The effects of polymer concentration, PEG content and polysorbate 80 coating on the particle size, drug loading efficiency and release behaviour of nanoparticles were investigated. Additionally, cellular uptake and brain targeting of formulated nanoparticles were studied. Particle sizes were in the range of 30-172 nm depending on formulation parameters. Increasing the polymer concentration significantly increased the nanoparticle size. Decreasing the PEG content from 15% to 5% (w/w) in polymer composition increased the nanoparticle size from 69 to 172 nm. Both coated and uncoated polysorbate 80 nanoparticles were effectively internalised within the endothelial cells. Moreover, both types of nanoparticles were able to penetrate the blood brain barrier and reach the maximum in brain 1 h post injection. It was concluded that these nanoparticles are promising nanosystems for treatment of neurological disorders.

Effects of vascular bundle implantation on autograft, fresh-frozen allograft, and xenograft incorporation in a rabbit model.

This study examined the effects of vascular bundle implantation into a bone graft. Vascularized and nonvascularized autografts, allografts, and xenografts were placed inside defects in the proximal tibia in rabbits. Evaluation using radiographs, magnetic resonance imaging, bone scintigraphy, and microscopy showed autografts fused more rapidly than allografts and xenografts, and the majority of the vascularized grafts were incorporated completely. Autografts emerged as the gold standard. These findings indicate vessel implantation enhances and accelerates vascularization, new bone formation, and incorporation in autografts, allografts, and xenografts.