Viability and function of primary human endothelial cells on smooth poly(ether imide) films

Abstract

Poly(ether imide) (PEI) is being explored as potential biomaterial for cardiovascular applications.Different studies showed that human umbilical venous endothelial cells (HUVEC) are able to adhere and proliferate on PEI membranes (R q = 13.20 ± 1.58 nm). A recently published study revealed evidence for much lower platelet adhesion on very smooth PEI-films (R q = 2.37 ± 1.40 nm). Therefore, we explored whether primary human venous endothelial cells (HUVEC) are able to adhere and proliferate on such very smooth PEI-films compared to tissue-cultured polystyrene (TCP) as reference material.Cytotoxicity testing revealed that PEI had a slight cytotoxic effect on HUVEC accompanied by a marginal reduced integrity of the plasma membrane and a significant lower mitochondrial activity.However long-term seeding experiments up to eleven days exhibited that HUVEC were able to proliferate on the PEI-films till confluence (TCP 96,190 ± 18,289 cells/cm²; PEI 91,590 ± 19,583 cells/cm²). Further studies are planned to monitor the influence of shear force on the endothelial cell monolayer in a dynamic test system to determine its stability in view of shear resistant endothelialization of PEI for cardiovascular devices. -draft version paper - Viability and function of primary human endothelial cells on smooth poly(ether imide) filmsDipl.-Biochem. Christian Schulz Seite 2 von 21 16.08.2012 Validation of remaining solvent by headspace GCSteam sterilized PEI-film (1 g, ~150 cm²) was incubated in a sealed sample flask with 9 ml Millipore water under shaking at 37 °C for 96 hours. The supernatant atmosphere was analyzed by gas chromatography (GC) using headspace GC (HP 7694 Headspace-Sampler, HP 5890 Series II GC, DB-624, 75m column).-draft version paper - Viability and function of primary human endothelial cells on smooth poly(ether imide) filmsDipl.-Biochem. Christian Schulz Seite 4 von 21 16.08.2012 Surface characterization by contact angle and atomic force measurements (AFM)Surface contact angle measurements (DSA 100, Krüss, captive bubble, water -air) were carried out at three different areas of each sample (n = 3) analyzing the advancing (Ѳ adv. ) and receding (Ѳ rec. ) contact angle with subsequent calculating of the hysteresis.Surface topography of the PEI-films was characterized by using atomic force microscopy (AFM, NanoScope, MultiMode V, Bruker Nano GmbH, tapping mode). Prior the samples were pre-wetted in phosphate buffered saline without calcium and magnesium ions (PBS -/-) at pH 7.4. The scanning area for each scan was 50 µm square size. Surface mean roughness (R a ) and mean square roughness (R q ) were determined by analyzing three samples on three different areas. Endotoxin loadThe endotoxin load of the PEI-film (n = 4) was determined by using the Limulus amebocyte lysate (LAL) test (QCL 1000™, Lonza, Cologne, Germany). Cell culture L929-fibroblastsL929-fibroblasts (NCTC clone 929) from the connective tissue of mice were purchased from ATCC (LGC Standards GmbH, Wesel, Germany) and cultured under static cell culture co...

In vivobiocompatibility assessment of poly (ether imide) electrospun scaffolds

“…Although endothelial cells seeded on PEI films showed decreased cell density after 48 h, cells grew to confluence in long‐term seeding experiments. Analyses of cytoskeletal proteins proved a comparable formation of actin filaments and focal adhesions of endothelial cells on PEI films and on control surfaces, facilitating the development of proper cell–cell and cell–matrix interactions (Schulz et al ., ). Furthermore, it could be shown that cells on PEI films secreted lower amounts of the inflammatory cytokine IL‐6 compared to cells on control surfaces, indicating an anti‐inflammatory effect of the PEI material (Schulz et al ., ).…”

“…Analyses of cytoskeletal proteins proved a comparable formation of actin filaments and focal adhesions of endothelial cells on PEI films and on control surfaces, facilitating the development of proper cell–cell and cell–matrix interactions (Schulz et al ., ). Furthermore, it could be shown that cells on PEI films secreted lower amounts of the inflammatory cytokine IL‐6 compared to cells on control surfaces, indicating an anti‐inflammatory effect of the PEI material (Schulz et al ., ). These results suggest that PEI materials exhibit properties that point to good in vivo biocompatibility, making them potential implant biomaterials.…”

“…In the present study, the in vivo biocompatibility of porous scaffolds built from randomly orientated fibres was compared to solid PEI films with a smooth surface in a model of subcutaneous implantation in mice. Previous in vitro studies showed that cells attach to and grow on flat PEI films and scaffolds (Peluso et al ., ; Rüder et al ., ; Schneider et al ., ; Schulz et al ., ; Seifert et al ., ; Tzoneva et al ., ). Although endothelial cells seeded on PEI films showed decreased cell density after 48 h, cells grew to confluence in long‐term seeding experiments.…”

“…A simple route to tailor PEI surface properties, for example by grafting of functional groups, allows for the adaptation of surface properties to the respective application demands (Braune et al ., ; Neffe et al ., ; Seifert et al ., ; Tzoneva et al ., ), while very good membrane‐forming properties have also been reported for PEI (Kneifel and Peinemann, ; Peinemann et al ., ). With regard to biocompatibility, PEI materials exert minimal cytotoxicity, good haemocompatibility (Imai et al ., ; Richardson et al ., ; Rüder et al ., ; Schulz et al ., ; Tzoneva et al ., ), are immunocompatible (Roch et al ., ) and allow for the attachment and growth of different cell types (Kawakami et al ., ; Kim et al ., ; Schneider et al ., ; Schulz et al ., ; Tzoneva et al ., ). On the basis of these results, PEI membranes have emerged as suitable materials for blood‐contacting applications, such as blood detoxification and oxygenation (Kawakami et al ., ).…”

“…Although PEI has shown great promise for biomedical applications through numerous in vitro studies, especially with vascular cells (Kim et al ., ; Lange et al ., ; Roch et al ., ; Schulz et al ., ; Tzoneva et al ., ) and initial in vivo biocompatibility tests of PEI bulk samples (Peluso et al ., ), the impact of basic material topography on the implant reaction has not yet been investigated. In an effort to expand the previously made observations, we investigated the biocompatibility of two basic forms of material morphology in a physiologically relevant in vivo model.…”