Meyer, A. A. | Search bioRxiv

bioRxiv2026

Effects of MRI on an Injectable Hydrogel with Magnetically Alignable Microstructures for Oriented Cell Growth

Injectable biomaterials with aligned microstructures play a critical role in tissue engineering and drug-delivery applications where control over the position and orientation of cells and nano/micron-scale architectures enhance intervention efficacy. Patients are often subject to MRI scans; for patient safety and treatment efficacy, we investigated the effects of MRI on a biomaterial treatment consisting of aligned magnetic microstructures being developed for guiding cell growth. Under MRI exposure, potential movement of aligned structures could be detrimental to nearby cells, and potential MRI-induced heating could adversely affect traumatized tissue. In this work, the alignment state and heat conduction of such a treatment were studied using a 9.4 T preclinical MRI. The treatment comprises short magnetic rod-shaped polycaprolactone fibers (rods) with embedded magnetic nanoparticles in a surrounding hydrogel (gelatin methacrylate), with rod alignment observed before and after a 45-minute MRI scan. No change in rod alignment state was observed, and no heat generation was measured. A theoretical framework was developed which supports the experimental observation that the biomaterial is stable under MRI. This work can be extended to other biomaterial systems with aligned architectures used in tissue engineering applications such as spinal cord, muscle and tendon.

bioengineering↗

bioRxiv2025

Fabrication of Short Polymeric μFibers as Building Blocks for Anisotropic High-Throughput Compatible 3D Tissue Models

Modeling the 3D microenvironment and cell growth of natively anisotropic human tissues in vitro constitutes a significant challenge in tissue engineering and biofabrication. Short polymeric fibers gain growing attention in this field due to their applicability as pipettable or injectable anisometric building blocks in 3D hydrogel-based cell culture systems or bioinks. However, the production of monodisperse short fibers with high production rates suitable for screening remains challenging. In this study, short, quasi-monodisperse, magneto-responsive, fluorescent poly({varepsilon}-caprolactone) {micro}fibers with variable dimensions in the micrometer range are produced in a scalable, semi-continuous two-step fabrication process combining controlled wet-dry spinning with subsequent cryosectioning. Influences of the spinning process parameters on fiber properties and process features, as well as boundary spinning conditions and upscaling potential, are explored using Design of Experiments approaches. Further, magnetic alignment of the {micro}fibers in a weak magnetic field and incorporation of nile red as fluorescent dye for facile analysis in 3D are demonstrated. Implementation of aligned {micro}fibers into a hydrogel-based 3D vasculogenesis model, produced in a high-throughput automated manner, is shown to stimulate oriented cell growth. This highlights the potential of our {micro}fibers as guiding elements inside tissue and disease models and their suitability for automated high-throughput applications.

bioengineering↗