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Background Aims: Stem cells participate in vascular regeneration following critical ischemia. However, their angiogenic and remodeling properties, as well as their role in ischemia-related endothelial leukocyte activation, need to be further elucidated. Herein, we investigated the effect of bone marrow-derived mesenchymal stromal cells (BM-MSCs) in a critically ischemic murine skin flap model., Methods: Groups received either 1 × 10(5), 5 × 10(5), or 1 × 10(6) BM-MSCs or cell-free conditioned medium (CM). Controls received sodium chloride. Intravital fluorescence microscopy was performed for morphological and quantitative assessment of micro-hemodynamic parameters over 12 days., Results: Tortuosity and diameter of conduit-arterioles were pronounced in the MSC groups (P < 0.01), whereas vasodilation was shifted to the end arteriolar level in the CM group (P < 0.01). These effects were accompanied by angiopoietin-2 expression. Functional capillary density and red blood cell velocity were enhanced in all treatment groups (P < 0.01). Although a significant reduction of rolling and sticking leukocytes was observed in the MSC groups with a reduction of diameter in postcapillary venules (P < 0.01), animals receiving CM exhibited a leukocyte-endothelium interaction similar to controls. This correlated with leukocyte common antigen expression in tissue sections (P < 0.01) and p38 mitogen-activated protein kinase expression from tissue samples. Cytokine analysis from BM-MSC culture medium revealed a 50% reduction of pro-inflammatory cytokines (interleukin [IL]-1β, IL-6, IL-12, tumor necrosis factor-α, interferon-γ) and chemokines (keratinocyte chemoattractant, granulocyte colony-stimulating factor) under hypoxic conditions., Discussion: We demonstrated positive effects of BM-MSCs on vascular regeneration and modulation of endothelial leukocyte adhesion in critical ischemic skin. The improvements after MSC application were dose-dependent and superior to the use of CM alone., (Copyright © 2014 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.)

Purpose: Geographic atrophy (GA) is the end-stage manifestation of atrophic age-related macular degeneration (AMD). The disease progresses slowly over time, eventually causing loss of central vision. Its cause and pathomechanism are not fully known. Previous studies have suggested that vitreoretinal traction (VRT) may contribute to the progression of neovascular AMD. The aim of this study was to examine whether an association between changes at the vitreoretinal interface (VRI), in particular traction (VRT), and the characteristics and progression of GA in eyes with dry AMD can be established., Design: Clinic-based prospective cohort study., Participants: A total of 97 patients (age range, 61-90 years; mean, 78.4 years) with GA secondary to dry AMD were enrolled. Patients exhibiting neovascular signs on fluorescein angiography in either eye were excluded., Methods: The VRI changes were examined using spectral-domain optical coherence tomography (SD-OCT). Characteristics of GA were examined using fundus autofluorescence (FAF) imaging. All imaging was performed using a Spectralis SLO+OCT device (Heidelberg Engineering, Heidelberg, Germany); GA area was measured using the Region Finder (Heidelberg Engineering) software native to the Spectralis platform., Main Outcome Measures: Area and increase in area of GA., Results: A total of 97 eyes were examined. Vitreoretinal traction was found in 39 eyes (40%). The GA area at baseline was 6.65±5.64 mm(2) in eyes with VRT and 5.73±4.72 mm(2) in eyes with no VRT. The annual rate of progression of GA area progression was 2.99±0.66 mm(2) in eyes with VRT and 1.45±0.67mm(2) in eyes without VRT. Differences between groups in both parameters were statistically significant (n = 97 total number of eyes; P<0.001). Multiple regression analysis confirmed this finding (B = 0.714, P<0.001; F3,93 = 72.542, P<0.001; adjusted R(2) = 0.691) CONCLUSIONS: Our results indicate an association between VRT and an increased rate of progression of GA area in dry AMD. Monitoring VRT may contribute to an improved estimate of the prospective time of visual loss and to a better timing of emerging therapies in dry AMD., (Copyright © 2014 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.)

Objective: In the rejection of transplanted retinal pigment epithelium (RPE) cells, an activation of allografts is probably the pivotal point for long-term success. The detailed immunological interactions involved in the rejection after RPE transplantation are still unknown. The aim of this study is to evaluate the interactions of pro-inflammatory cytokines and chemokines in this activation process in vitro., Methods: Human RPE cells (2 x 10(5)/ml) were therefore activated through a pre-treatment with different concentrations of interferon (IFN)-gamma (100 or 1000 U/ml), tumour necrosis factor (TNF)-alpha (1 or 10 ng/ml) or combinations of both, or employed in a nonactivated form. Afterwards, the RPE cells were tested by enzyme-linked immunosorbant assay (ELISA) and ribonuclease protection assays (RPA) for the secretion and mRNA content of the different chemokines (RANTES, MCP-1 and IL-8) and cytokines (IL-6) at various time points up to 48 h., Main Findings: HRPE cells secrete the investigated cytokines in response to pro-inflammatory activation. This could be demonstrated at both the mRNA (RPA) and the protein levels (ELISA). The secretion was time and dose dependent, and significantly upregulated in comparison to that observed with nonactivated cells., Conclusions: This study demonstrates that RPE cells efficiently secrete such cytokines as RANTES, MCP-1, IL-6, and IL-8, and have an accountable neutrophil and monocyte chemotactic activity. Thus, it could be indicated that the investigated cytokines play a central role in the activation cascade of RPE and in RPE rejection as well.

A modification of the MTT based tetrazolium colorimetric assay is described. Using the electron-coupling agent menadione formazan formation by murine splenocytes and P-815 cells was significantly increased whereas dye reduction by macrophages was hardly influenced. These observations suggest that it should be possible to improve the tetrazolium based cytotoxicity assays of murine macrophages against cells of the syngeneic tumour cell line P-815.