Browsing Publications of Dept. Gene Regulation and Differentiation (RDIF) by Subject (MeSH)
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Comparison of in vitro and in vivo protein release from hydrogel systems.Hydrogel systems based on hydroxyethyl starch-polyethylene glycol methacrylate (HES-P(EG)(6)MA) or hydroxyethyl starch methacrylate (HES-MA) were used to assess the protein release behavior. Here, we analyzed the in vitro release of FITC-anti-human antibodies incorporated in either HES-P(EG)(6)MA or HES-MA hydrogel delivery systems in PBS or human serum. In addition, hydrogel disks and microparticles prepared from the two polymers were subcutaneously implanted in BALB/c mice. The in vivo release of FITC-IgG was non-invasively monitored by an in vivo imaging system (IVIS 200) over a time period of up to 3 months. The imaging system allowed to asses individual animals over time, therefore only a small number of animals was required to obtain high quality data. The reduction in fluorescence intensity at the site of administration was compared to in vitro release profiles. These investigations demonstrated a sustained release from HES-MA hydrogel disks compared to rapidly degrading HES-P(EG)(6)MA disks and microparticles. The sustained release from HES-MA disks could be further optimized by using increased polymer concentrations. Human serum as in vitro release medium reflected better the in vivo release from HES-P(EG)(6)MA systems than PBS, suggesting that the presence of organic substances like proteins or lipids may play a significant role for the release kinetics.
Elevated expression of VEGFR-3 in lymphatic endothelial cells from lymphangiomas.BACKGROUND: Lymphangiomas are neoplasias of childhood. Their etiology is unknown and a causal therapy does not exist. The recent discovery of highly specific markers for lymphatic endothelial cells (LECs) has permitted their isolation and characterization, but expression levels and stability of molecular markers on LECs from healthy and lymphangioma tissues have not been studied yet. We addressed this problem by profiling LECs from normal dermis and two children suffering from lymphangioma, and also compared them with blood endothelial cells (BECs) from umbilical vein, aorta and myometrial microvessels. METHODS: Lymphangioma tissue samples were obtained from two young patients suffering from lymphangioma in the axillary and upper arm region. Initially isolated with anti-CD31 (PECAM-1) antibodies, the cells were separated by FACS sorting and magnetic beads using anti-podoplanin and/or LYVE-1 antibodies. Characterization was performed by FACS analysis, immunofluorescence staining, ELISA and micro-array gene analysis. RESULTS: LECs from foreskin and lymphangioma had an almost identical pattern of lymphendothelial markers such as podoplanin, Prox1, reelin, cMaf and integrin-alpha1 and -alpha9. However, LYVE-1 was down-regulated and VEGFR-2 and R-3 were up-regulated in lymphangiomas. Prox1 was constantly expressed in LECs but not in any of the BECs. CONCLUSION: LECs from different sources express slightly variable molecular markers, but can always be distinguished from BECs by their Prox1 expression. High levels of VEGFR-3 and -2 seem to contribute to the etiology of lymphangiomas.
Mandibular bone repair by implantation of rhBMP-2 in a slow release carrier of polylactic acid--an experimental study in rats.The aim of the present study was to test the hypothesis that human recombinant bone morphogenic protein 2 (rhBMP-2) implanted in a slow release carrier of polylactic acid (PLA) can repair a non-healing defect in the rat mandible and maintain the thickness of an augmented volume. p-DL-lactic acid discs were produced and loaded with 48 and 96 microg rhBMP-2 and inserted into non-healing defects of the mandible of 45 Wistar rats. Fifteen rats received implants with 96 microg rhBMP-2 (Group 2), 48 microg rhBMP-2 (Group 1) and blank implants without BMP (Group 0) each on one side of the mandible. Unfilled defects of the same size on the contralateral sides of the mandibles served as empty controls. After 6, 13 and 26 weeks, implants of each group were retrieved from five animals each and submitted to flat panel detector computed tomography. Bone formation and thickness of augmentation was assessed by computer-assisted histomorphometry. In Group 2 significantly more bone was produced than in Group 1. Implants of Group 1 induced significantly more bone than the blank controls only after 6 weeks, whereas the difference was not significant after 13 and 26 weeks. Differences between Group 2 and Group 1 were clearly significant after 26 weeks. The thickness of bone tissue was maintained in Group 2 whereas it decreased in Group 1 and was negligible in Group 0. It is concluded that the PLA implants with 96 microg rhBMP-2 were able to bridge a non-healing defect in the rat mandible and maintained the thickness of an augmented volume. However, continuous supply of osteogenic signals appears to be required to compensate for adverse effects during polymer degradation.
Whole-blood flow-cytometric analysis of antigen-specific CD4 T-cell cytokine profiles distinguishes active tuberculosis from non-active states.T-cell based IFN-γ release assays do not permit distinction of active tuberculosis (TB) from successfully treated disease or latent M. tuberculosis infection. We postulated that IFN-γ and IL-2 cytokine profiles of antigen-specific T cells measured by flow-cytometry ex vivo might correlate with TB disease activity in vivo. Tuberculin (PPD), ESAT-6 and CFP-10 were used as stimuli to determine antigen-specific cytokine profiles in CD4 T cells from 24 patients with active TB and 28 patients with successfully treated TB using flow-cytometry. Moreover, 25 individuals with immunity consistent with latent M. tuberculosis infection and BCG-vaccination, respectively, were recruited. Although the frequency of cytokine secreting PPD reactive CD4 T cells was higher in patients with active TB compared to patients with treated TB (median 0.81% vs. 0.39% of CD4 T cells, p = 0.02), the overlap in frequencies precluded distinction between the groups on an individual basis. When assessing cytokine profiles, PPD specific CD4 T cells secreting both IFN-γ and IL-2 predominated in treated TB, latent infection and BCG-vaccination, whilst in active TB the cytokine profile was shifted towards cells secreting IFN-γ only (p<0.0001). Cytokine profiles of ESAT-6 or CFP-10 reactive CD4 T cells did not differ between the groups. Receiver operator characteristics (ROC) analysis revealed that frequencies of PPD specific IFN-γ/IL-2 dual-positive T cells below 56% were an accurate marker for active TB (specificity 100%, sensitivity 70%) enabling effective discrimination from non-active states. In conclusion, a frequency lower than 56% IFN-γ/IL-2 dual positive PPD-specific circulating CD4 T-cells is strongly indicative of active TB.