Introduction

Polyvinyl alcohol hydrogel (PVA-H) vascular models have emerged as valuable tools in medical training and the devel-opment of vascular implants, offering advantages over in vivo studies. However, creating complex anatomical models, such as large-sac aneurysms, requires sacrificial materials compatible with PVA-H to form the vessel lumen.

Methods

This study explors various sacrificial materials, including carbohydrate glass and different wax mixtures, for fabricating vascular lumens. Preliminary characterizations assess lumen stability during PVA-H crosslinking, solubility in appropri-ate solvents, and the physical and mechanical properties of PVA-H after sacrificial lumen dissolution. Following optimi-zation of physical and mechanical properties of the selected sacrificial material, a combination of 3D printing and mold-ing technologies were used to fabricate big-sac aneurysms.

Results

Fabrication of complex aneurysm lumens using carbohydrate glass and different wax mixtures was achievable. Howev-er, carbohydrate glass exhibited premature dissolution upon contact with PVA-H. Different wax types showed varying melting temperatures, ranging between 53°C and 60°C, with melting times of up to 30 minutes . Dissolution times for the wax lumens from anatomical big-sac and standardized aneurysms were less than 30 minutes, differing among wax types. The compliance of PVA-H aneurysms closely resembled that of natural vessels, falling within the range of 0.4% to 0.5 % per mmHg.

Conclusion

This study demonstrates the feasibility of fabricating complex vascular models using PVA-H and sacrificial materials. Compared to carbohydrate glass, wax emerged as the optimal sacrificial material due to its stability and dissolution properties. These findings offer promising results for fabrication of accurate complex anatomical vascular models based of hydrogel with a potential of advancing medical training and testing of vascular implants.

Despite the wide variety of knitting patterns present in the global market for synthetic meshes, the influence of mesh morphology on the mechanical behaviour of these devices is not yet clear. The goal of this project is to determine how the mechanical properties of monofilament polypropylene warp-knitted meshes are influenced by their morphological characteristics. Multivariate linear regression models were developed using nine meshes to quantify a correlation between these two crucial aspects. Additionally, porous mesoscale Finite Element (FE) models were implemented in Abaqus to replicate in vitro tests conducted in a previous study. High values of the determination coefficient were obtained for all the models and their robustness was confirmed by good performance in a leave one out validation method. The porous FE models successfully replicated the multidirectional behaviour of the meshes after the calibration of the elastic modulus based on the uniaxial tensile test. This combined approach demonstrates valuable results paving the way for advancements in hernia treatment and meshes design.

Introduction

Laser-induced periodic surface structures (LIPSS) offer the potential to engineer cell adhesion, cell orientation, and cell density on implant surfaces through periodic structures on the nanometer and micrometer scale. However, the application of LIPSS on biomedical devices is highly limited due to limited fabrication techniques for polymeric implant surfaces. Within this study, methods of implementing LIPSS on a polymer possessing USP class VI certification and ISO 10993 proven biocompatibility are established.

Methods

The LIPSS are generated on a stainless steel plate by a femtosecond laser system embedded into a 4-axis CNC system. The structured substrate is used as a template for fabricating the polymer films by spray coating and spin coating. Fi-nally, the polymer films containing the LIPSS are transferred to flat metal and glass substrates for analysis by means of SEM and CLSM.

Results

Very homogeneous LIPSS are formed on the entire metal surface, possessing a periodicity of 951 nm and an averaged peak-to-valley height difference of 147 nm. A homogeneous structure is also found on the polymer films for both fabrication methods, resembling the inverted LIPSS. In comparison to the metal substrate, the surface structure is shrunk in peak-to-valley height as well as periodicity, which can be attributed to a shrinking of the polymer during drying.

Conclusion

A sequential process was used to fabricate LIPSS-like structures on polymeric surfaces. It is shown that besides the expected shrinking of the polymer, the LIPSS can perfectly be transferred to the polymer by two major fabrication techniques used in biomedical engineering: spin coating and spray coating. Due to the USP class VI certification and the ISO 10993 proved biocompatibility of the used polymer, the established process can directly be used to apply the field of nanostructured polymer surfaces to polymer-encapsulated or polymer-finished implants, i.e., devices containing flexible electronics, polymer-covered vascular implants, and implantable mechanical and electrical probes.

In vitro alveolar models are an important tool study respiratory physiology, investigate lung diseases, develop and test new therapies, and simulate inhalation exposure to environmental pollutants or therapeutic agents. A defined cell culture medium is essential for maintaining consistent and reliable in vitro models. In this study a defined cell culture medium for advanced alveolar models based on epithelial A549 cell line and endothelial EaHy926 cell line is developed. Cellular survival was proven by quantification of LDH release. It was shown that co-culture of the cells enhances cellular survival compared to the endothelial monoculture. The formation of a homogeneous monolayer on laminin coated membranes was confirmed by actin staining. Further, the expression of cell type specific proteins (endothelial: CD31, VE-cadherin; epithelial: ZO1 and E-cadherin) was shown. Overall, we demonstrated a completely defined cell culture medium that can be used for the setup of an advanced in vitro alveolar model for biomedical application like drug development or breath gas analysis.

Abstract:

A novel pathway for pro- and anti-angiogenesis was recently reported by our group, while

testing polymer phase biohybrids carrying immobilized bone morphogenetic protein (BMP-2)

in OEC/pOB cell co-cultures. Pro-angiogenic therapy e.g. for tissue regeneration and anti-

angiogenic therapy for combatting cancer, both based on vascular epithelial growth factor

(VEGF), are major therapeutic challenges of modem medicine. Thus antibody-targetting of

VEGF induced tumor vessels is often ineffective, due to the sudden emergence of quiescent,

circumventing blood vessls from unknown alternative pathways. In the present perspective

characteristic receptor properties of BMP-2 induced angiogenesis are compared to the

receptor properties of the omnipresent blood vessel-inducing VEGF, demonstrating VEGF-

independence of BMP-2 induced angiogenesis on the background of current therpeutic

challenges.

Abstract: In this paper, a thorough analysis of nanosecond

laser texturing on Ti-6A1-4V ELI material was carried out,

with a particular emphasis on the modulation of laser process

parameters and their effects on surface morphology,

elemental composition, microscale topographical features,

and wettability. The laser-textured samples exhibit unique

surface morphologies that were identified by different

topographical metrics such as average surface roughness

(Sa), surface development ratio (Sdr), peak-to-peak distance

(dp), and peak-to-valley height (hp) along parallel and

perpendicular to laser scanning directions. The energy

dispersive x-ray spectroscopy (EDS) was used to examine the

differences in elemental composition and crystallographic

constitution of the samples revealed using the x-ray

diffraction analysis (XRD). Further contact angle

measurement in both the parallel and perpendicular directions

revealed the hydrophobicity of the laser-textured surfaces.

Out of 4 samples, LT-2 and LT-4 samples displayed

noticeably larger contact angles, demonstrating a high degree

of hydrophobicity in both directions. Improved

hydrophobicity of the textured surfaces may lead to reduced

bacterial attachment, whereas anisotropic surface features at

the microscale may provide contact guidance to osteoblast

cells, opening up avenues for regenerative tissue engineering

on biomaterial interfaces.