Impact of Secondary Reactive Species on the Apparent Decoupling of Poly(Ethylene Glycol) Diacrylate Hydrogel Average Mesh Size and Modulus

Poly(ethylene glycol) diacrylate (PEGDA) hydrogels are widely used in biotechnology due to their in situ crosslinking capacity and tunable physical properties. However, as with all single component hydrogels, the modulus of PEGDA networks cannot be tailored independently of mesh size. This interdependence places significant limitations on their use for defined, 3D cell-microenvironment studies and for certain controlled release applications. The incorporation of secondary reactive species (SRS) into PEGDA hydrogels has previously been shown to allow the identification of up to 6 PEGDA hydrogel formulations for which distinct moduli can be obtained at consistent average mesh size (or vice versa). However, the modulus and mesh size ranges which can be probed by these formulations are quite restricted. This work presents an in-depth study of SRS incorporation into PEGDA hydrogels, with the goal of expanding the space for which decoupled examination of modulus and mesh size effects is achievable. Towards this end, over 100 PEGDA hydrogels containing either N-vinyl pyrrolidone or star PEG-tetraacrylate as SRS were characterized. To our knowledge, this is the first study to demonstrate that SRS incorporation allows for the identification of a number of modulus ranges that can be probed at consistent average mesh size (or vice versa)

Dehydrated Human Amnion/Chorion Membrane Allograft Nerve Wrap Around the Prostatic Neurovascular Bundle Accelerates Early Return to Continence and Potency Following Robot-assisted Radical Prostatectomy: Propensity Score–matched Analysis

Abstract We present a propensity-matched analysis of patients undergoing placement of dehydrated human amnion/chorion membrane (dHACM) around the neurovascular bundle (NVB) during nerve-sparing (NS) robot-assisted laparoscopic prostatectomy (RARP). From March 2013 to July 2014, 58 patients who were preoperatively potent (Sexual Health Inventory for Men [SHIM] score >19) and continent (no pads) underwent full NS RARP. Postoperative outcomes were analyzed between propensity-matched graft and no-graft groups, including time to return to continence, potency, and biochemical recurrence. dHACM use was not associated with increased operative time or blood loss or negative oncologic outcomes ( p >0.500). Continence at 8 wk returned in 81.0% of the dHACM group and 74.1% of the no-dHACM group ( p =0.373). Mean time to continence was enhanced in group 1 patients (1.21 mo) versus (1.83 mo; p =0.033). Potency at 8 wk returned in 65.5% of the dHACM patients and 51.7% of the no-dHACM group ( p =0.132). Mean time to potency was enhanced in group 1, (1.34 mo), compared to group 2 (3.39 mo; p =0.007). Graft placement enhanced mean time to continence and potency. Postoperative SHIM scores were higher in the dHACM group at maximal follow-up (mean score 16.2 vs 9.1). dHACM allograft use appears to hasten the early return of continence and potency in patients following RARP

Collagen-Mimetic Hydrogels Promote Human Endothelial Cell Adhesion, Migration and Phenotypic Maturation

This work evaluates the response of human aortic endothelial cells (HAECs) to thromboresistant collagen-mimetic hydrogel coatings toward improving the biocompatibility of existing off-the-shelf small-caliber vascular grafts. Specifically, bioactive hydrogels-previously shown to support α1/α2 integrin-mediated cell adhesion but to resist platelet activation-were fabricated by combining poly(ethylene glycol) (PEG) with a 120 kDa, triple-helical collagen-mimetic protein (Scl2-2) containing the GFPGER adhesion sequence. Analysis of HAECs seeded onto the resulting PEG-Scl2-2 hydrogels demonstrated that HAEC adhesion increased with increasing Scl2-2 concentration, while HAEC migration rate decreased over this same concentration range. In addition, evaluation of HAEC phenotype at confluence indicated significant differences in the gene expression of NOS3, thrombomodulin, and E-selectin on the PEG-Scl2-2 hydrogels relative to PEG-collagen controls. At the protein level, however, only NOS3 was significantly different between the PEG-Scl2-2 and PEG-collagen surfaces. Furthermore, PECAM-1 and VE-cadherin expression on PEG-Scl2-2 hydrogels versus PEG-collagen controls could not be distinguished at either the gene or protein level. Cumulatively, these data indicate the PEG-Scl2-2 hydrogels warrant further investigation as off-the-shelf graft coatings. In future studies, the Scl2-2 protein can potentially be modified to include additional extracellular matrix or cytokine binding sites to further improve endothelial cell responses

PERIOPERATIVE AND ONCOLOGICAL OUTCOMES IN HIGH RISK ELDERLY PATIENTS

Aim of the study ontroversy continues to exist concerning the treatment of choice for D\u2019Amico high risk elderly patients. The purpose of this study is to compare the perioperative and oncologic outcomes of robotic assisted radical prostatectomy (RARP) in D\u2019Amico high risk, propensity score-matched elderly and younger cohorts. Materials and methods From January 2008 through August 2012, 3818 patients underwent RARP at our institution by a single surgeon (VP). Retrospective analysis of prospectively collected data from our Institutional Review Board approved registry identified 80 D\u2019Amico high risk patients, 70 years of age and over. A propensity scorematch analysis was conducted using multivariable analysis to compare elderly patients (age 70 and over) to those under 70. The final two study cohorts \u2013 D\u2019Amico high risk elderly patients (n=80) and D\u2019Amico high risk younger patients (n=80) constituted the clinical material for this comparative study of perioperative and oncologic outcomes. Results Preoperative clinical characteristics were similar for the two matched groups. The operative time, transfusion rate and intra-operative complications were similar for the two groups.The mean estimated blood loss was significantly greater in younger patients (156.1 \ub1 84.2 mLvs 113.6 \ub1 67.7; p=0.002). No significant differences were observed in laterality, ease of nerve sparing or surgeon subjectively assessed anastomosis and pathological outcomes between the groups. No significant differences were found in postoperative complication rates, overall pain scores, length of stay or duration of indwelling catheterization. At follow-up, freedom from biochemical recurrence (BCR) in elderly patients was 85.0% vs. 83.8% in younger patients. The mean time to BCR in elderly patients was 15.0 months (range, 2.3 to 38.8) and 14.5 months (range, 5.2 to 35.1) in younger patients. Discussion Conclusions This study clearly demonstrates that RARP can be performed in D\u2019Amico high risk elderly patients without increasing perioperative morbidity and with oncologic outcomes comparable to high risk younger patients. RARP in elderly patients presenting with localized prostate cancer should be considered a viable treatment alternative based on the individual\u2019s life expectancy

3D printing for the development of in vitro cancer models

In vitro engineering of tumor milieus is complex because cancer progression and metastasis involve spatio-temporally evolving cell-matrix interactions, myriad interactions between tumor cells and auxiliary cells, hypoxic cores, leaky unorganized vasculature and a host of signaling molecules. Recent advances in 3D printing approaches enable the precise placement of cells, bioactive factors and biomaterials, thus permitting the recapitulation of several features associated with the in vivo tumor microenvironment. 3D printed in vitro tumor models can serve as robust platforms to study mechanisms of disease progression, enable high throughput screening of drugs and aid the development of next generation molecular therapies. This focused review discusses the importance and relevance of 3D printing technologies in building 3D tumor models in vitro. Several recent 3D printed cancer models are discussed, as also the evolution and features of next-generation models

Experimental investigation of instabilities in charged polymer solutions

Electrospinning is a process that utilizes electric fields to create non-woven fibrous matrices. The main goal of the work is to determine the effect of potential drop

Fabrication of electrospun meshes from natural polymers for biomedical applications

Diabetic retinopathy (DR) involves a progressively worsening cycle of microglial cell activation and inflammation that leads to severe retinal damage. While the inflammatory nature of DR is well-established, the exact role of microglial cells in contributing to disease progression is not clear. Towards the long-term goal of creating in vitro platforms to understand microglial cells responses in health/disease, the objective of this work is to create electrospun substrates from natural polymers with systematically varying properties for the in vitro culture of microglial cells. Accordingly, gelatin and composite nanofibers with different diameters and architectures were successfully electrospun. Increasing the concentration of gelatin in solution resulted in a slight increase in fiber diameter. Concurrently, a 10% (w/v) gelatin solution was mixed with 10% polycaprolactone (PCL) solution at a ratio of 50:50 and electrospun to produce gelatin/ PCL composite nanofibers. In a parallel study, fiber architecture was varied by changing the collector geometry. While randomly oriented gelatin and PCL fibers (with angular standard deviation >50°) were generated by electrospinning onto a flat plate collector, semi-aligned (with angular standard deviation >30°) and highly aligned fibers (with angular standard deviation <20°) were collected by using a drum collector rotating at 750 rpm and 1500 rpm respectively. To improve the stability of gelatin in aqueous environments, nanofibers were crosslinked with glutaraldehyde (GTA) vapor at room temperature for different time periods, namely 2h, 6h, 12h and 24h. While the non-crosslinked control fibers almost entirely degraded within 1 day of exposure to aqueous buffer at 37 °C, fibers crosslinked with GTA for 2h or more remained stable for at least four days in buffer, indicating that 2h was sufficient to retard degradation. Culture of primary mixed retinal cells on randomly oriented and aligned fibers resulted in randomly oriented and highly aligned vimentin and cell nuclei. In summary, the work demonstrates that the properties of gelatin meshes can be changed by systematically varying electrospinning parameters. In the future, the effects of fiber diameter and chemistry on cell phenotypic activation will be studied. Furthermore, fibers will be tethered with cytokines that can be released in a controlled manner through fiber degradation

A Three-Dimensional Chondrocyte-Macrophage Coculture System to Probe Inflammation in Experimental Osteoarthritis

The goal of the present study was to develop a fully three-dimensional (3D) coculture system that would allow for systematic evaluation of the interplay between activated macrophages (AMs) and chondrocytes in osteoarthritic disease progression and treatment. Toward this end, our coculture system was first validated against existing in vitro osteoarthritis models, which have generally cultured healthy normal chondrocytes (NCs)—in two-dimensional (2D) or 3D—with proinflammatory AMs in 2D. In this work, NCs and AMs were both encapsulated within poly(ethylene glycol) diacrylate hydrogels to mimic the native 3D environments of both cell types within the osteoarthritic joint. As with previous studies, increases in matrix metalloproteinases (MMPs) and proinflammatory cytokines associated with the early stages of osteoarthritis were observed during NC-AM coculture, as were decreases in protein-level Aggrecan and collagen II. Thereafter, the coculture system was extended to osteoarthritic chondrocytes (OACs) and AMs to evaluate the potential effects of AMs on pre-existing osteoarthritic phenotypes. OACs in coculture with AMs expressed significantly higher levels of MMP-1, MMP-3, MMP-9, MMP-13, IL-1β, TNF-α, IL-6, IL-8, and IFN-γ compared to OACs in mono-culture, indicating that proinflammatory macrophages may intensify the abnormal matrix degradation and cytokine secretion already associated with OACs. Likewise, AMs cocultured with OACs expressed significantly more IL-1β and VEGF-A compared to AM mono-culture controls, suggesting that OACs may intensify abnormal macrophage activation. Finally, OACs cultured in the presence of nonactivated macrophages produced lower levels of MMP-9 and proinflammatory cytokines IL-1β, TNF-α, and IFN-γ compared to OACs in the OAC-AM system, results that are consistent with anti-inflammatory agents temporarily reducing certain OA symptoms. In summary, the 3D coculture system developed herein captures several key features of inflammatory OA and may prove useful in future screening of therapeutic agents and/or assessment of disease progression mechanisms