Enhanced wound healing by topical administration of mesenchymal stem cells transfected with stromal cell-derived factor-1.

The objective of this study was to investigate the ability of mesenchymal stem cells (MSC) genetically engineered with stromal cell-derived factor-1 (SDF-1) to heal skin wounds. When transfected with SDF-1 plasmid DNA, MSC which were isolated from the bone marrow of rats, secreted SDF-1 for 7 days. In vitro cell migration assay revealed that the SDF-1-engineered MSC (SDF-MSC) enhanced the migration of MSC and dermal fibroblasts to a significantly greater extent than MSC. The SDF-MSC secreted vascular endothelial growth factor, hepatocyte growth factor, and interleukin 6 at a significantly high level. A skin defect model of rats was prepared and MSC and SDF-MSC were applied to the wound to evaluate wound healing in terms of wound size and histological examinations. The wound size decreased significantly faster with SDF-MSC treatment than with MSC and PBS treatments. The length of the neoepithelium and the number of blood vessels newly formed were significantly larger. A cell-tracing experiment with fluorescently labeled cells demonstrated that the percent survival of SDF-MSC in the tissue treated was significantly high compared with that of MSC. It was concluded that SDF-1 genetic engineering is a promising way to promote the wound healing activity of MSC for a skin defect.

Gelatin nanospheres incorporating siRNA for controlled intracellular release.

The objective of this study is to develop a sustained release system of small interfering RNA (siRNA) inside cells aiming at a prolonged time period of gene suppression. Gelatin aqueous solution containing luciferase siRNA was coacelvated by acetone addition, followed by the glutaraldehyde (GA) crosslinking of gelatin to prepare gelatin nanospheres incorporating siRNA. The nanospheres were degraded with time in phosphate-buffered saline solution containing collagenase to release siRNA incorporated. The nanospheres were degraded more slowly as the GA concentration become higher, and consequently the rate of siRNA become lower. siRNA was released from the nanospheres as a result of nanospheres degradation. The nanospheres were internalized into colon 26 cells luciferase stably expressed, irrespective of the GA concentration. The gene expression was suppressed by the nanospheres incorporating siRNA capable for the longer-term release, and subsequently the time period of gene suppression was prolonged. The siRNA release inside the cell was observed, while the release period became longer for the slow-degraded nanospheres. It is possible that the intracellular siRNA release for a longer time period contributes to the prolonged time period of gene suppression.

Liver Anti-Fibrosis Therapy with Mesenchymal Stem Cells Secreting Hepatocyte Growth Factor.

The objective of this study is to investigate the anti-fibrotic effect of combined mesencymal stem cells (MSCs) and gene therapy on liver fibrosis. When transfected by the complex with a plasmid DNA of hepatocyte growth factor (HGF) and the spermine-introduced pullulan of gene carrier, MSCs secreted HGF protein over 1 week. The HGF secreted from transfected MSC had the biological activity to promote the albumin production of hepatocytes. After intravenous injection, the HGF-secreting MSCs (HGF-MSC) accumulated in the liver. The injection of HGF-MSC decreased the fibrosis area in a rat model of liver fibrosis to a significantly great extent compared with that of original MSC. In the in vitro experiment, the higher number of HGF-transfected MSCs was migrated by stromal cell-derived factor (SDF)-1α more strongly than the original MSC. Considering the promotion of SDF-1α secretion in the liver fibrosis, it is possible that, when transplanted, genetically-engineered MSCs are accumulated in the liver due to their higher response to SDF-1α. It is concluded that the intravenous injection of genetically-engineered MSCs is a promising therapy for liver fibrosis.

Molecular characteristics of outbreaks of nosocomial infection with influenza A/H3N2 virus variants.

OBJECTIVE: To describe outbreaks of nosocomial influenza infection with molecular methods and to elucidate the viral linkages among outbreak case patients including both inpatients and healthcare workers (HCWs). SETTING: A 180-bed acute and long-term care hospital in Japan. METHODS: Retrospective observational study of nosocomial outbreaks of infection with influenza A/H3N2. Together with information about onset dates and vaccination history, we obtained nasopharyngeal swab samples from individuals with cases of influenza or influenza-like illness (ILI). The hemagglutinin genes of the recovered viruses were sequenced and compared, along with those of community-circulating strains, for similarity by phylogenetic tree analysis. RESULTS: The outbreaks occurred from February 26 through April 3, 2007, during the 2006-2007 epidemic season, and they involved 11 patients and 13 HCWs. The 2 outbreaks involved 2 different genotypes of influenza A/H3N2 viruses. These virus variants were closely related to the influenza strains that were circulating in the community during the same epidemic season. CONCLUSION: This study showed the dissemination of highly homologous influenza virus variants among inpatients and HCWs within a short period, as a result of nosocomial transmission. These strains were also similar to influenza strains that were circulating in the community.

High prevalence of amantadine-resistance influenza a (H3N2) in six prefectures, Japan, in the 2005-2006 season.

Substantial increase in amantadine-resistant influenza A (H3N2) was reported in Asia and North America in 2005. In this study the frequency and genetic characteristics of amantadine-resistant influenza A, circulated in Japan in 2005-2006 season, were investigated. Isolates were tested by amantadine susceptibility test (TCID(50)/0.2 ml method), and sequencing of the M2 gene to identify mutations that confer resistance. Additionally, the hemagglutinin (HA) and neuraminidase (NA) genes of the viruses were examined. In total, 415 influenza A isolates from six prefectures were screened, and 231 (65.3%) of 354 influenza A (H3N2) were amantadine-resistant, with a serine to asparagine (S31N) change in the M2 gene. However, none of 61 A (H1N1) isolates were resistant. In addition, genetic analyses of the HA gene showed all amantadine-resistant viruses clustered in one (named clade N), possessing specific double mutations at 193, serine to phenylalanine (S193F), and at 225, asparatic acid to asparagine (D225N), and sensitive viruses belonged to another group (clade S). The clinical presentations at the clinical visit did not differ between patients shedding clade N virus and those shedding clade S virus. None of the patients had received previous treatment with amantadine. The results indicate an unusually high prevalence and wide circulation of the amantadine-resistance influenza A (H3N2) in Japan in the 2005-2006 season. These strains had the characteristic double mutations in the HA, in addition to the M2 mutation responsive for resistance. Antiviral resistance monitoring should be intensified and maintained for rapid feedback into treatment strategies, and selection of alternative therapeutic agents.