Comparison of Six Different Silicones In Vitro for Application as Glaucoma Drainage Device

Tetrapodal ZnO-Based Composite Stents for Minimally Invasive Glaucoma Surgery

The glaucoma burden increases continuously and is estimated to affect more than 100 million people by 2040. As there is currently no cure to restore the optic nerve damage caused by glaucoma, the only controllable parameter is the intraocular pressure (IOP). In recent years, minimally invasive glaucoma surgery (MIGS) has emerged as an alternative to traditional treatments. It uses micro-sized drainage stents that are inserted through a small incision, minimizing the trauma to the tissue and reducing surgical and postoperative recovery time. However, a major challenge for MIGS devices is foreign body reaction and fibrosis, which can lead to a complete failure of the device. In this work, the antifibrotic potential of tetrapodal ZnO (t-ZnO) microparticles used as an additive is elucidated by using rat embryonic fibroblasts as a model. A simple, direct solvent-free process for the fabrication of stents with an outer diameter of 200-400 μm is presented, in which a high amount of t-ZnO particles (45-75 wt %) is mixed into polydimethylsiloxane (PDMS) and a highly viscous polymer/particle mixture is extruded. The fabricated stents possess increased elastic modulus compared to pure PDMS while remaining flexible to adapt to the curvature of an eye. In vitro experiments showed that the fibroblast cell viability was inhibited to 43 ± 3% when stents with 75 wt % t-ZnO were used. The results indicate that cell inhibiting properties can be attributed to an increased amount of protruding t-ZnO particles on the stent surface, leading to an increase in local contacts with cells and a disruption of the cell membrane. As a secondary mechanism, the released Zn ions could also contribute to the cell-inhibiting properties in the close vicinity of the stent surface. Overall, the fabrication method and the antifibrotic and mechanical properties of developed stents make them promising for application in MIGS.

Biological evaluation of preceramic organosilicon polymers for various healthcare and biomedical engineering applications: A review

Preceramic organosilicon materials combining the properties of a polymer and an inorganic ceramic phase are of great interest to scientists working in biomedical sciences. The interdisciplinary nature of organosilicon polymers and their molecular structures, as well as their diversity of applications have resulted in an unprecedented range of devices and synergies cutting across unrelated fields in medicine and engineering. Organosilicon materials, especially the polysiloxanes, have a long history of industrial and medical uses in many versatile aspects as they can be easily fabricated into complex-shaped products using a wide variety of computer-aided or polymer manufacturing techniques. Thus far, intensive research activities have been mainly devoted to the processing of preceramic organosilicon polymers toward magnetic, electronic, structural, optical, and not biological applications. Herein we present innovative research studies and recent developments of preceramic organosilicon polymers at the interface with biological systems, displaying the versatility and multi-functionality of these materials. This article reviews recent research on preceramic organosilicon polymers and corresponding composites for bone tissue regeneration and medical engineering implants, focusing on three particular topics: (a) surface modifications to create tailorable and bioactive surfaces with high corrosion resistance and improved biological properties; (b) biological evaluations for specific applications, such as in glaucoma drainage devices, orthopedic implants, bone tissue regeneration, wound dressing, drug delivery systems, and antibacterial activity; and (c) in vitro and in vivo studies for cytotoxicity, genotoxicity, and cell viability. The interest in organosilicon materials stems from the fact that a vast array of these materials have complementary attributes that, when integrated appropriately with functional fillers and carefully controlled conditions, could be exploited either as polymeric Si-based composites or as organosilicon polymer-derived Si-based ceramic composites to tailor and optimize properties of the Si-based materials for various proposed applications.

Characterization of six canine prostate adenocarcinoma and three transitional cell carcinoma cell lines derived from primary tumor tissues as well as metastasis

Canine prostate adenocarcinoma (PAC) and transitional cell carcinoma (TCC) of prostate and urinary bladder are highly invasive and metastatic tumors of closely neighbored organs. Cell lines are valuable tools to investigate tumor mechanisms and therapeutic approaches in vitro. PAC in dogs is infrequent, difficult to differentiate from TCC and usually characterized by poor prognosis, enhancing the value of the few available cell lines. However, as cell lines adapt to culturing conditions, a thorough characterization, ideally compared to original tissue, is indispensable. Herein, six canine PAC cell lines and three TCC cell lines were profiled by immunophenotype in comparison to respective original tumor tissues. Three of the six PAC cell lines were derived from primary tumor and metastases of the same patient. Further, two of the three TCC cell lines were derived from TCCs invading into or originating from the prostate. Cell biologic parameters as doubling times and chemoresistances to commonly used drugs in cancer treatment (doxorubicin, carboplatin and meloxicam) were assessed. All cell lines were immunohistochemically close to the respective original tissue. Compared to primary tumor cell lines, metastasis-derived cell lines were more chemoresistant to doxorubicin, but equally susceptive to carboplatin treatment. Two cell lines were multiresistant. COX-2 enzyme activity was demonstrated in all cell lines. However, meloxicam inhibited prostaglandin E2 production in only seven of nine cell lines and did neither influence metabolic activity, nor proliferation. The characterized nine cell lines represent excellent tools to investigate PAC as well as TCC in prostate and urinary bladder of the dog. Furthermore, the profiled paired cell lines from PAC primary tumor and metastasis provide the unique opportunity to investigate metastasis-associated changes PAC cells undergo in tumor progression. The combination of nine differently chemoresistant PAC and TCC cell lines resembles the heterogeneity of canine lower urinary tract cancer.

Isoquinolinamine FX-9 Exhibits Anti-Mitotic Activity in Human and Canine Prostate Carcinoma Cell Lines

Current therapies are insufficient for metastatic prostate cancer (PCa) in men and dogs. As human castrate-resistant PCa shares several characteristics with the canine disease, comparative evaluation of novel therapeutic agents is of considerable value for both species. Novel isoquinolinamine FX-9 exhibits antiproliferative activity in acute lymphoblastic leukemia cell lines but has not been tested yet on any solid neoplasia type. In this study, FX-9′s mediated effects were characterized on two human (PC-3, LNCaP) and two canine (CT1258, 0846) PCa cell lines, as well as benign solid tissue cells. FX-9 significantly inhibited cell viability and induced apoptosis with concentrations in the low micromolar range. Mediated effects were highly comparable between the PCa cell lines of both species, but less pronounced on non-malignant chondrocytes and fibroblasts. Interestingly, FX-9 exposure also leads to the formation and survival of enlarged multinucleated cells through mitotic slippage. Based on the results, FX-9 acts as an anti-mitotic agent with reduced cytotoxic activity in benign cells. The characterization of FX-9-induced effects on PCa cells provides a basis for in vivo studies with the potential of valuable transferable findings to the benefit of men and dogs.

Comparison of two prototypes of a magnetically adjustable glaucoma implant in rabbits

Glaucoma drainage devices are used in surgical glaucoma therapy. Success of controlling the intraocular pressure is limited due to fibrous implant encapsulation and fibrin coating on the implant which lead to drainage obstructions. An innovative implant with a magnetically adjustable valve was developed. The valve opening of the implant should eliminate inflammatory products from the outflow area and affect fibrous tissue formation to achieve a sufficient long-term aqueous humour outflow. Lifting of this valve should disturb cell adhesion by exerting mechanical forces. Before testing this hypothesis, the flow characteristics of glaucoma drainage devices, especially the outflow resistance by regular IOP, should be considered in a pilot study, as they are important in preventing too low postoperative intraocular pressure known as ocular hypotony. Therefore, two prototypes of the innovative implant differing in their valve area design were examined regarding their flow characteristics in a limited animal experiment lasting two weeks. Ten healthy New Zealand White rabbits were divided into two groups (A & B) with different implanted prototypes. Daily, tonometry and direct ophthalmoscopy were performed to assess the intraocular pressure and the inflammatory reaction of the eye. After two weeks, the rabbits were euthanised to evaluate the initially histological inflammatory reaction to the implant. In group A, one case of hypotony emerged. When considering the entire observation period, a highly statistically significant difference between the intraocular pressure in the operated eye and that in the control eye was detected in group A (p < 0.0001) in contrast to group B (p = 0.0063). The postoperative inflammatory signs decreased within two weeks. Histologically, a typical but low level foreign body reaction with macrophages and lymphocytes as well as mild to moderate fibrosis was seen after the short experimental period. Based on our tonometric results, prototype B seems to be the system of choice for further research assessing its long-term function and biocompatibility.

The Study of a New Modified Bicanalicular Intubation for the Repairment of Traumatic Canalicular Laceration

Introduction

To investigate the efficacy and safety of a modified bicanalicular intubation (MBCI) used in canalicular laceration.

Materials and Methods

This study is a retrospective consecutive chart review. A total of 43 eyes from 43 patients (36 males and 7 females) who underwent canalicular intubation were enrolled. Success rate was determined at 6 months after the surgery. Anatomical success was determined by diagnostic probing and irrigation; functional success was determined by asking patients about tearing.

Results

Irrigation of the lacrimal passages in all 43 eyes showed that they were free from obstruction. The anatomical success was 100%, and 37 eyes (86%) achieved functional success. 6 eyes (14%) could not achieve functional success because there were some residual symptoms under irritating conditions, such as wind or winter weather, among which 2 eyes had bicanalicular lacerations and 4 eyes had lower canalicular laceration before surgery. There were no other complications observed in this study.

Conclusions

The MBCI was simple and safe for using in canalicular laceration.