Enhanced Efficacy of Human Brain-Derived Neural Stem Cells by Transplantation of Cell Aggregates in a Rat Model of Parkinson's Disease

OBJECTIVE: Neural tissue transplantation has been a promising strategy for the treatment of Parkinson's disease (PD). However, transplantation has the disadvantages of low-cell survival and/or development of dyskinesia. Transplantation of cell aggregates has the potential to overcome these problems, because the cells can extend their axons into the host brain and establish synaptic connections with host neurons. In this present study, aggregates of human brain-derived neural stem cells (HB-NSC) were transplanted into a PD animal model and compared to previous report on transplantation of single-cell suspensions. METHODS: Rats received an injection of 6-OHDA into the right medial forebrain bundle to generate the PD model and followed by injections of PBS only, or HB-NSC aggregates in PBS into the ipsilateral striatum. Behavioral tests, multitracer (2-deoxy-2-[18F]-fluoro-D-glucose ([18F]-FDG) and [18F]-N-(3-fluoropropyl)-2-carbomethoxy-3-(4-iodophenyl)nortropane ([18F]-FP-CIT) microPET scans, as well as immunohistochemical (IHC) and immunofluorescent (IF) staining were conducted to evaluate the results. RESULTS: The stepping test showed significant improvement of contralateral forelimb control in the HB-NSC group from 6-10 weeks compared to the control group (p<0.05). [18F]-FP-CIT microPET at 10 weeks posttransplantation demonstrated a significant increase in uptake in the HB-NSC group compared to pretransplantation (p<0.05). In IHC and IF staining, tyrosine hydroxylase and human beta2 microglobulin (a human cell marker) positive cells were visualized at the transplant site. CONCLUSION: These results suggest that the HB-NSC aggregates can survive in the striatum and exert therapeutic effects in a PD model by secreting dopamine.

Simvastatin inhibits osteoclast differentiation by scavenging reactive oxygen species

Osteoclasts, together with osteoblasts, control the amount of bone tissue and regulate bone remodeling. Osteoclast differentiation is an important factor related to the pathogenesis of bone-loss related diseases. Reactive oxygen species (ROS) acts as a signal mediator in osteoclast differentiation. Simvastatin, which inhibits 3-hydroxy-3-methylglutaryl coenzyme A, is a hypolipidemic drug which is known to affect bone metabolism and suppresses osteoclastogenesis induced by receptor activator of nuclear factor-kappaB ligand (RANKL). In this study, we analyzed whether simvastatin can inhibit RANKL-induced osteoclastogenesis through suppression of the subsequently formed ROS and investigated whether simvastatin can inhibit H2O2-induced signaling pathways in osteoclast differentiation. We found that simvastatin decreased expression of tartrate-resistant acid phosphatase (TRAP), a genetic marker of osteoclast differentiation, and inhibited intracellular ROS generation in RAW 264.7 cell lines. ROS generation activated NF-kappaB, protein kinases B (AKT), mitogen-activated protein kinases signaling pathways such as c-JUN N-terminal kinases, p38 MAP kinases as well as extracellular signal-regulated kinase. Simvastatin was found to suppress these H2O2-induced signaling pathways in osteoclastogenesis. Together, these results indicate that simvastatin acts as an osteoclastogenesis inhibitor through suppression of ROS-mediated signaling pathways. This indicates that simvastatin has potential usefulness for osteoporosis and pathological bone resorption.

Calcification Comparison of Polymers for Vascular Graft

Polytetrafluoroethylene (PTFE), polyurethane (PU) and silicone are widely known biocompatible polymers which are commonly used for vascular grafts. However, in vitro and in vivo calcifications of these polymers have been found to seriously compromise their quality as biomaterials. In consideration of this problem, the present study compared the calcification rate and extent of PTFE, PU and silicone. Using the in vitro flow-type method, PTFE, PU and silicone films were tested for 1, 4, 7, 10, 14 and 21 days. After 21 days of in vitro calcification test, the calcium levels on PTFE, PU and silicone were 35.89 5.01 microgram /cm2, 23.73 0.68 microgram/cm2 and 19.86 5.28 microgram/cm2, respectively. The higher observed calcium level for PTFE may be due to the effect of the rough surface of PTFE in accumulating calcium ions on the polymer surface. From the 7th day of test, the [Ca]/[P] molar ratio started to decrease over time, and PTFE showed a faster calcification process. This decreasing [Ca]/[P] molar ratio demonstrated the typical calcification mechanism consisting of phosphorus ion accumulation following calcium ion accumulation. This study concluded that PU and silicone are less calcified than PTFE film, a finding in good agreement with previously published studies.

Characterization of UV-irradiated dense/porous collagen membranes: morphology, enzymatic degradation, and mechanical properties

Collagen-based membranous materials of various shapes (gel, film, sponge) are known to be the most promising materials in terms of facilitating the regeneration of dermal defects. In this study, dense and porous collagen membranes were fabricated using air-drying and freeze-drying processes, respectively, and the effect of ultraviolet (UV) radiation on the degree of membrane crosslinking was evaluated by in vitro biodegradation and mechanical testing. A non-irradiated membrane group was used as the negative control and a glutaraldehyde (GA) treated group as the positive control. Scanning electron microscopy showed that, as the freezing temperature decreased to -196 degrees C, the resultant mean pore sizes also decreased; optimal pore size was obtained at a freezing temperature of -70 degrees C. In vitro biodegradation and mechanical testing demonstrated that GA treatment or 4 hours of exposure to UV radiation significantly increased both resistance to collagenase and mechanical strength versus the untreated controls, regardless of the collagen membrane type (dense or porous). Our results suggest that UV treatment is a useful tool for the fabrication of collagen membranes designed to be used as dermal dressings.

Viability evaluation of engineered tissues

Biohybrid artificial organs encompass all devices capable of substituting for an organ or tissue function and are fabricated from both synthetic materials and living cells. The viability of engineered tissue could be related to the viability of implanted cells. The system of viability assay for mammalian cell culture can be applied to the determination of cell viability for engineered tissue. This review explores various methods of cell viability assay which can be applied to the viability evaluation of engineered tissue. The major criteria employed in viability assays include survival and growth in tissue culture, functional assay, metabolite incorporation, structural altercation, and membrane integrity. Each viability assay method is based on different definitions of cell viability, and has inherent advantages and disadvantages. In order to be able to assess the viability of cells with one assay method, it is desirable to compare the viability measurements from various assays derived from different criteria.