Collagen distribution in the human vitreoretinal interface

PURPOSE. To evaluate the presence of collagen types I to VII, IX, XI, and XVIII at the posterior pole, the equator and the preequatorial area in human donor eyes, since collagens are important macromolecules that contribute to vitreoretinal adhesion at the vitreoretinal interface. METHODS. Freshly isolated human retinectomy samples from the equator were used for reverse transcription-polymerase chain reaction to detect mRNA of the above-mentioned collagens. In addition, human donor eyes and equatorial retinectomy samples were embedded in paraffin, stained with antibodies against the collagens and evaluated by light microscopy (LM). RESULTS. Retinectomy samples expressed mRNA of all tested collagen types. By LM, vitreous cortex was positive for collagen types II, V, IX, and XI. In all three regions within the donor eyes and in the retinectomy samples, the internal limiting membrane (ILM) showed types IV, VI, and XVIII; the retinal vasculature was positive for types I to VI and XVIII in most specimens; and the retinal layers showed condensed spots of type VII. In addition, type VII increased in density and in distribution over the retinal layers toward the posterior pole. CONCLUSIONS. Staining patterns of collagen types I to V, IX, XI, and XVIII confirmed previous observations. Important new findings include the presence of type VI in the ILM and type VII in several layers of the retina. Both collagens can anchor matrix components, and type VI could be involved in vitreoretinal attachment. Furthermore, the presence of collagen mRNA in human retinectomy samples may be an indication of postnatal collagen production by retinal cells

Dissemination of rat cytomegalovirus through infected granulocytes and monocytes in vitro and in vivo

The role of leukocytes in the in vivo dissemination of cytomegalovirus was studied in this experiment. Rat cytomegalovirus (RCMV) could be transferred to rat granulocytes and monocytes by cocultivation with RCMV-infected fibroblasts in vitro. Intravenous injection of purified infected granulocytes or monocytes resulted in a systemic infection in rats, indicating that our model is a powerful tool to gain further insight into CMV dissemination and the development of new antivirals

Human adipose tissue-derived stromal cells act as functional pericytes in mice and suppress high-glucose-induced proinflammatory activation of bovine retinal endothelial cells

The immunomodulatory capacity of adipose tissue-derived stromal cells (ASCs) is relevant for next-generation cell therapies that aim to reverse tissue dysfunction such as that caused by diabetes. Pericyte dropout from retinal capillaries underlies diabetic retinopathy and the subsequent aberrant angiogenesis. We investigated the pericytic function of ASCs after intravitreal injection of ASCs in mice with retinopathy of prematurity as a model for clinical diabetic retinopathy. In addition, ASCs influence their environment by paracrine signalling. For this, we assessed the immunomodulatory capacity of conditioned medium from cultured ASCs (ASC-Cme) on high glucose (HG)-stimulated bovine retinal endothelial cells (BRECs). ASCs augmented and stabilised retinal angiogenesis and co-localised with capillaries at a pericyte-specific position. This indicates that cultured ASCs exert juxtacrine signalling in retinal microvessels. ASC-Cme alleviated HG-induced oxidative stress and its subsequent upregulation of downstream targets in an NF-kappa B dependent fashion in cultured BRECs. Functionally, monocyte adhesion to the monolayers of activated BRECs was also decreased by treatment with ASC-Cme and correlated with a decline in expression of adhesion-related genes such as SELE, ICAM1 and VCAM1. The ability of ASC-Cme to immunomodulate HG-challenged BRECs is related to the length of time for which ASCs were preconditioned in HG medium. Conditioned medium from ASCs that had been chronically exposed to HG medium was able to normalise the HG-challenged BRECs to normal glucose levels. In contrast, conditioned medium from ASCs that had been exposed to HG medium for a shorter time did not have this effect. Our results show that the manner of HG preconditioning of ASCs dictates their immunoregulatory properties and thus the potential outcome of treatment of diabetic retinopathy

Extracellular matrix components of adipose derived stromal cells promote alignment, organization, and maturation of cardiomyocytes in vitro

Adipose derived stromal cells (ADSC) are relevant therapeutic agents to treat myocardial infarction (MI) in clinical trials. Soluble factors secreted by ADSC, such as growth factors and cytokines, suppress inflammation and apoptosis while promoting angiogenesis and the proliferation of cardiomyocytes (CM). Moreover, ADSC synthesize extracellular matrix (ECM) components into the intercellular space which might contribute to their therapeutic capacity. Thus, ADSC might directly modulate the post-MI microenvironment through a combination of paracrine and juxtacrine signaling. In this study, the juxtacrine role of ADSC and ADSC-derived ECM on the organization and maturation of CM was investiagated. Human ADSC synthesized and deposited a heterogenous and complex mixture of ECM components such as collagen I, III, IV, fibronectin, elastin as well as the matricellular protein periostin. Cocultures of rodent CM with human ADSC or with human ADSC-derived ECM components enhanced the cardiomyocyte alignment, their intercellular connections and the maturation of their sarcomeres, while the proliferation rate of the CM was increased and their level of hypertrophy reduced. The use of human ADSC-derived ECM could serve both to augment in vitro tissue-engineered myocardial constructs and to improve myocardial remodeling after infarction. (c) 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 1840-1848, 2015

Endothelial progenitor cell-based neovascularization:implications for therapy

Ischemic cardiovascular events are a major cause of death globally. Endothelial progenitor cell (EPC)-based approaches can result in improvement of vascular perfusion and might offer clinical benefit. However, although functional improvement is observed, the lack of long-term engraftment of EPCs into neovessels has raised controversy regarding their mechanism of action. We and others have hypothesized that after ischemic injury, EPCs induce neovascularization through the secretion of cytokines and growth factors, which act in a paracrine fashion and induce sprouting angiogenesis by the surrounding endothelium. In this concise review, we discuss the (patho)physiology of EPC-induced neovascularization and focus on the paracrine signals secreted by EPCs and the effects they elicit. In future therapies, clinical administration of these paracrine modulators using slow-release depots might induce neovascularization and might therefore hold promise for vascular regenerative medicine

Cytokine and chemokine dynamics differ between rats and mice after collagen implantation

Implanted scaffold materials induce an inflammatory reaction known as the 'foreign body reaction' (FBR). We hypothesized that the observed difference in FBR between rats and mice correlate with different expression dynamics of cytokines and chemokines, which are key orchestrators of the FBR. After implantation of hexamethylene diisocyanate cross-linked dermal sheep collagen, the overall gene expression pattern of IL-1, IL-6, IL-10, TNF alpha, CXCL1/KC, CXCL2/MIP2 and CCL2/MCP1 was roughly similar for the two species. During the onset of the FBR these genes were maximally expressed in rats and mice, after which the expression decreased to basal levels. The expression of CCL3/MIP1 alpha had a similar course, yet it increased after the progression phase of the FBR in both species. The expression of cytokines and chemokines in sham-operated animals was low throughout, showing that the implanted material by itself exerted the changes in gene expression of the invading cells. During the progression, genes encoding the PMN attractants CXCL1/KC and CXCL2/MIP2 were more highly expressed in mice than in rats, which would explain the prolonged presence of PMNs in mice during the FBR. Additionally, the strong induction of IFN gamma in rats coincided with a higher phagocytotic activity by macrophages. Throughout the FBR, the expression of TGF beta was constitutive and high in both species, but increased in mice during the progression phase. This could explain the extensive stroma formation during the murine FBR. Unexpectedly, the stronger expression of TNFa and CCL3/MIP1 alpha in mice, did not result in high macrophage attraction or phagocytosis of the implanted collagen disks. Copyright (c) 2007 John Wiley & Sons, Ltd

Cellular and molecular dynamics in the foreign body reaction

Intracorporally implanted materials, such as medical devices, will provoke the body to initiate an inflammatory reaction. This inflammatory reaction to implanted materials is known as the foreign body reaction (FBR) and is characterized by 3 distinct phases: onset, progression, and resolution. The FBR proceeds in the creation of a dynamic microenvironment that is spatially well organized. The progression of the FBR is regulated by soluble mediators, such as cytokines, chemokines, and matrix metalloproteinases ( MMPs), which are produced locally by tissue cells and infiltrated inflammatory cells. These soluble mediators orchestrate the cascade of cellular processes in the microenvironment that accompanies the FBR, consisting of cellular activation, angiogenesis, extravasation, migration, phagocytosis, and, finally, fibrosis. The nature of the FBR requires that the soluble mediators act in a spatial and temporally regulated manner as well. This regulation is well known for several inflammatory processes, but scarce knowledge exists about the intricate relationship between the FBR and the expression of soluble mediators. This review discusses the key processes during the initiation, progression, and resolution phase, with emphasis on the role of soluble mediators. Besides other sites of implantation, we focus on the subcutaneous implantation model

The local inflammatory environment and microorganisms in "Aseptic" loosening of hip prostheses

Long term loosening of hip prostheses remains an important problem in orthopedics. Although various loosening mechanisms have been proposed, the exact process is still unclear. Particle disease and the pressure theory are widely known and generally accepted hypotheses to explain long term implant failure. Each proposed mechanism recognizes a local inflammatory response in which macrophages represent the main cell-type and several proinflammatory and antinflammatory cytokines (IL-1 beta, IL-6, TNF alpha, IL-10, TGF beta), chemokines (IL-8/CXCL8, MCP-I/CCL2, RANTES/CCL5, MIP-1 alpha/CCL3) and other mediators (GM-CSF, M-CSF, MMP-1, PDGF-alpha, PGE(2), IL-11) are identified. The cytokines have different functions and some are capable of stimulating bone resorption in various ways; either directly or indirectly. Even though the implant loosening is thought to be "aseptic", several studies suggested a possible role for bacteria and a bacterial biofilm in implant failure. Biofilm-derived bacteria and bacterial products might have an underestimated and potential role in the loosening process. In this article we will discuss the possible role of a bacterial biofilm and the importance of the local surrounding environment in "aseptic" loosening of hip prostheses. (C) 2007 Wiley Periodicals, Inc