Combined 5-Fluorouracil and Low Molecular Weight Heparin for the Prevention of Postoperative Proliferative Vitreoretinopathy in Patients with Retinal Detachment

Review question / Objective: The aim of this meta-analysis is to evaluate the efficacy and safety of intraoperative infusion of combined 5-fluorouracil and low molecular weight heparin (LMWH) for the prevention of postoperative proliferative vitreoretinopathy in patients with retinal detachment. Condition being studied: Postoperative proliferative vitreoretinopathy (PVR) is the primary cause of failure of retinal reattachment surgery. 5-fluorouracil (5-FU) inhibits the proliferation of fibroblasts, and suppresses collagen contraction. On the other hand, heparin reduces fibrin exudation, and inhibits the adhesion and migration of retinal pigment epithelial cells. We conduct this comprehensive literature search and meta-analysis to address whether intraoperative infusion of combined 5-FU and LWMH improves the primary success rate of pars plana vitrectomy, as well as reduces postoperative PVR. Our study aims to provide clinical evidence for retinal surgeons concerning their choice of intraoperative medication.

An Oenothera biennis Cell Cultures Extract Endowed with Skin Anti-Ageing Activity Improves Cell Mechanical Properties

Skin aging is a very well-known process setting a gradual worsening of skin mechanical features due to a decline in the production of the extra-cellular matrix machinery and to a concurrent change in the contraction process. To slow this progression, it is crucial to induce the expression of several proteins able to promote elastic fibers formation and tissue repair. Here, the Oenothera biennis cell culture aqueous extract has been investigated from a chemical point of view and then it was tested in vitro, in cell, and in ex vivo experiments as adjuvant in counteracting skin aging. Accordingly, it has been shown that the Oenothera biennis extract was able, by increasing MYLK gene expression, to promote matrix collagen contraction, actin polymerization, and the production of essential ECM proteins.

Contractile Effects of Radiofrequency Energized Helium Plasma on the Fibrous Septal Network

Body contouring with liposuction has evolved significantly from the early approach of simply debulking excess fatty tissue, to affecting the mechanical properties of different tissue types and layers. Operative paradigms have been expanded to apply energy-based technologies intraoperatively to provide more uniform aspiration, selective fatty tissue emulsification in soft and fibrous body areas, minimize trauma to nerves and vessels, expose the fibrous septal network, reduce operator fatigue and help deliver smooth shapes with less discomfort and bruising. Advanced refinements with the delivery of monopolar and bipolar radiofrequency energy for soft tissue heating have been shown to reduce the residual soft tissue laxity that often follows voluminous fat removal. The Renuvion® (Apyx™ Medical, Clearwater, FL) radiofrequency powered helium plasma technology introduces an emerging concept in which the delivery of subdermal thermal energy preferentially coagulates the fascia and fibrous septal network through a conductive helium plasma stream seeking the path of least resistance, which in turn results in collagen contraction and tissue shrinkage that permits re-draping of the skin and enhanced definition. The physics and mechanics of Renuvion® subdermal soft tissue coagulation will be presented, along with clinical applications that have provided the authors more contouring finesse and has augmented liposuction outcomes.

Abstract 16406: Epigenetic Regulation of Myofibroblast Differentiation and Persistence is Mediated by Enhanced Glutaminolysis

Cardiac fibrosis is mediated by the activation and differentiation of resident cardiac fibroblasts. While initially reparative, chronic activation leads to progressive cardiac dysfunction. Associated with myofibroblast formation are changes in metabolites directly linked to the activity of epigenetic-modifying enzymes. To define the signaling linking fibroblast activation with changes to the epigenetic landscape, we treated primary adult murine cardiac fibroblasts (CFs) with the pro-fibrotic agonist, TGFβ, and subjected them to next-gen sequencing techniques (RNA-seq, ATAC-seq). Following activation, we observed alterations in chromatin accessibility corresponding to the transcriptional activation and suppression of key fibrotic genes. Intriguingly, increased chromatin accessibility was strongly associated with both transcriptional activation and suppression, while decreased accessibility correlated with neither transcriptional repression or activation. Regions of increased accessibility were enriched for canonical fibrotic TF binding motifs (e.g. SMADs, NFAT). We recently reported that αKG-dependent lysine demethylases may be required for myofibroblast formation, so we made correlative comparisons between chromatin remodeling and the synthesis and utilization of metabolites critical for (de)methylation by applying unbiased, stable isotope metabolomics. These studies indicated enhanced glutaminolysis as the driver of increased αKG abundance. In the presence of TGFβ, pharmacologic inhibition (CB-839) or genetic deletion ( Gls1 -/- ) of glutaminolysis prevented myofibroblast formation as indicated by αSMA positivity, fibrotic gene program activation, and collagen contraction assays. Following myofibroblast formation, inhibition of glutaminolysis was sufficient to revert activated myofibroblasts to a non-fibrotic phenotype, during sustained stress. Remarkably, these results were recapitulated in CFs from human heart failure patients. Collectively, these findings suggest that metabolic remodeling is necessary for the epigenetic modifications that underlie myofibroblast formation and persistence, providing substantial rationale to evaluate several new therapeutic targets to treat fibrosis.

The role of lamina cribrosa tissue stiffness and fibrosis as fundamental biomechanical drivers of pathological glaucoma cupping

The primary biomechanical driver of pathological glaucomatous cupping remains unknown. Finite element modeling indicates that stress and strain play key roles. In this article, primarily a review, we utilize known biomechanical data and currently unpublished results from our lab to propose a three-stage, tissue stiffness-based model to explain glaucomatous cupping occurring at variable levels of translaminar pressure (TLP). In stage 1, a short-term increase in TLP gradient induces a transient increase in lamina cribrosa (LC) strain. Beyond a critical level of strain, the tissue stiffness rises steeply provoking cellular responses via integrin-mediated mechanotransduction. This early mechanoprotective cellular contraction reduces strain, which reduces tissue stiffness by return of the posteriorly deflected LC to baseline. In stage 2 a prolonged period of TLP increase elicits extracellular matrix (ECM) production leading to fibrosis, increasing baseline tissue stiffness and strain and diminishing the contractile ability/ability to return to the baseline LC position. This is supported by our three-dimensional collagen contraction assays, which show significantly reduced capacity to contract in glaucoma compared with normal LC cells. Second, 15% cyclic strain in LC cells over 24 h elicits a typical increase in ECM profibrotic genes in normal LC cells but a highly blunted response in glaucoma LC cells. Stage 3 is characterized by persistent fibrosis causing further stiffening and inducing a feed-forward ECM production cycle. Repeated cycles of increased strain and stiffness with profibrotic ECM deposition prevent optic nerve head (ONH) recoil from the new deflected position. This incremental maladaptive modeling leads to pathological ONH cupping.

AR12286 Alleviates TGF-β-Related Myofibroblast Transdifferentiation and Reduces Fibrosis after Glaucoma Filtration Surgery

Scar formation can cause the failure of glaucoma filtration surgery. We investigated the effect of AR12286, a selective Rho-associated kinase inhibitor, on myofibroblast transdifferentiation and intraocular pressure assessment in rabbit glaucoma filtration surgery models. Cell migration and collagen contraction were used to demonstrate the functionality of AR12286-modulated human conjunctival fibroblasts (HConFs). Polymerase chain reaction quantitative analysis was used to determine the effect of AR12286 on the production of collagen Type 1A1 and fibronectin 1. Cell migration and collagen contraction in HConFs were activated by TGF-β1. However, compared with the control group, rabbit models treated with AR12286 exhibited higher reduction in intraocular pressure after filtration surgery, and decreased collagen levels at the wound site in vivo. Therefore, increased α-SMA expression in HConFs induced by TGF-β1 could be inhibited by AR12286, and the production of Type 1A1 collagen and fibronectin 1 in TGF-β1-treated HConFs was inhibited by AR12286. Overall, the stimulation of HConFs by TGF-β1 was alleviated by AR12286, and this effect was mediated by the downregulation of TGF-β receptor-related SMAD signaling pathways. In vivo results indicated that AR12286 thus improves the outcome of filtration surgery as a result of its antifibrotic action in the bleb tissue because AR12286 inhibited the TGF-β receptor-related signaling pathway, suppressing several downstream reactions in myofibroblast transdifferentiation.

TGF-β1 Activates Nasal Fibroblasts through the Induction of Endoplasmic Reticulum Stress

(1) Background: Tissue remodeling and extracellular matrix (ECM) accumulation contribute to the development of chronic inflammatory diseases of the upper airway. Endoplasmic reticulum (ER) stress is considered to be the key signal for triggering tissue remodeling in pathological conditions. The present study aimed to investigate the role of ER-stress in TGF-β1-stimulated nasal fibroblasts and inferior turbinate organ cultures; (2) Methods: Fibroblasts and organ cultures were pretreated with 4-phenylbutyric acid (PBA) and stimulated with TGF-β1 or thapsigargin (TG). Expression of ER-stress markers, myofibroblast marker, and ECM components was measured by Western blotting and real-time PCR. Reactive oxygen species (ROS) were quantified using 2′,7′-dichlorofluorescein diacetate. Cell migration was evaluated using Transwell assays. Contractile activity was measured by collagen contraction assay; (3) Results: 4-PBA inhibited TGF-β1 or TG-induced ER-stress marker expression, phenotypic changes, and ECM. Pre-treatment with ROS scavengers inhibited the expression of TGF-β1-induced ER-stress markers. Migration and collagen contraction of TGF-β1 or TG-stimulated fibroblasts were ameliorated by 4-PBA treatment. These findings were confirmed in ex vivo organ cultures; (4) Conclusions: 4-PBA downregulates TGF-β1-induced ER-stress marker expression, migration, and collagen contraction via ROS in fibroblasts and organ cultures. These results suggest that ER-stress may play an important role in progression of chronic upper airway inflammatory diseases by aiding pathological tissue remodeling.

Isolation and Characterization of an Adult Stem Cell Population from Human Epidural Fat

Study Design. Isolation and characterization of human epidural fat (HEF) stem/progenitor cells. Objective. To identify a progenitor population within HEF and to determine if they meet the minimal criteria of a mesenchymal stem cell (MSC). Summary of Background Data. The biological function, if any, has yet to be determined for HEF. The presence of MSCs within HEF may indicate a regenerative potential within the HEF. Methods. HEF was isolated from 10 patients during elective spinal surgery. HEF cells were differentiated along osteo-, adipo-, and chondrogenic lineages, with differentiation analyzed via qPCR and histology. The cell surface receptor profile of HEF cells was examined by flow cytometry. HEF cells were also assayed through the collagen contraction assay. Prx1CreERT2GFP:R26RTdTomato MSC lineage-tracking mice were employed to identify EF MSCs in vivo. Results. HEF cell lines were obtained from all 10 patients in the study. Cells from 2/10 patients demonstrated full MSC potential, while cells from 6/10 patients demonstrated progenitor potential; 2/10 patients presented with cells that retained only adipogenic potential. HEF cells demonstrated MSC surface marker expression. All patient cell lines contracted collagen gels. A Prx1-positive population in mouse epidural fat that appeared to contribute to the dura of the spinal cord was observed in vivo. Conclusions. MSC and progenitor populations are present within HEF. MSCs were not identified in all patients examined in the current study. Furthermore, all patient lines demonstrated collagen contraction capacity, suggesting either a contaminating activated fibroblast population or HEF MSCs/progenitors also demonstrating a fibroblast-like phenotype. In vivo analysis suggests that these cell populations may contribute to the dura. Overall, these results suggest that cells within epidural fat may play a biological role within the local environment above providing a mechanical buffer.