Speaker
Description
Introduction
Cartilage defects present significant challenges in long-term repair, with current treatments, such as cell-based therapies, often failing to restore sustained biomechanical function due to poor integration and/or lack of type II collagen organization[1]. The native depth-dependent fiber orientations in the arched collagen structure provide the mechanical support necessary to withstand cyclic loading in the joints[2]. Melt Electrofibrillation (MEF), a novel biofabrication technique, creates aligned polycaprolactone (PCL) nanofibers through polymer blend phase separation[3]. In contrast to traditional Melt Electrowriting (MEW) microfibers, we hypothesized that MEF nanofibers can guide type II collagen organization during chondrogenesis. This approach offers a pioneering solution for the development of functional articular cartilage tissue.
Methods
PCL microfibers (MEW) and PCL/polyvinyl acetate (PVAc) nanofibers (MEF) were printed using a custom-built MEW platform. PVAc was dissolved by incubating the MEF constructs in 70% ethanol and PBS, thereby exposing the PCL nanofibrils. Fiber diameters were characterized using scanning electron microscopy (Fig.1A). Rhombus-shaped scaffolds were seeded with equine articular cartilage progenitor cells (ACPCs, 5×10⁶ cells/ml) to assess cell–material interactions (Fig.1B) using immunofluorescence (DAPI/Actin/Collagen-II). To replicate the native arched collagen architecture of articular cartilage (Fig. 1C), sinusoidal constructs of 288 layers were fabricated with an overall height of up to 1 mm (Fig.1D). ACPCs were seeded and chondrogenically differentiated for 28 days, and collagen alignment analysed by picrosirius red staining and polarized light microscopy, with orientation assessed via Fiji software (Fig.1E).
Results
The MEF generated fibers had significant smaller diameter (560 ± 160 nm) when compared to MEW microfibers (9 ± 1 µm) (Fig.1A). The nanofibers effectively guided ACPC alignment (Fig.1B) and supported organized type II collagen deposition. In contrast, cells on MEW-only scaffolds formed aggregates, with collagen primarily deposited around these clusters. Interestingly, ACPCs seeded on constructs with arched MEF nanofibres were distributed uniformly throughout the constructs and after 28 days of culture type II collagen structures were observed that followed the underlying fiber orientation (Fig.1E), resulting in arched collagen networks.
Conclusion
To the best of our knowledge, this study provides the first evidence of material-guided type II collagen organisation by chondrocytes. Using the MEF technology will thus enable us to control the type II collagen structures within engineered cartilage constructs, which opens new possibilities for engineering implants that can provide long-term mechanical stability.
References
[1] G. R. Talesa et al., 2022.
[2] A. Pueyo Moliner et al., 2025
[3] M. Ryma et al., 2021
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