Francesco Iorio

Tendon injuries present significant healing challenges due to poor vascularization and limited regenerative capacity, requiring engineered scaffolds that provide both mechanical support and biological guidance. Current electrospinning methods for fabricating such fibrous scaffolds commonly rely on toxic solvents, creating environmental and safety concerns. Here we report the fabrication of aligned polycaprolactone/gelatin (PCL/GEL) electrospun fibers with covalently conjugated heparin (HEP) using a benign binary solvent system. Uncrosslinked PCL/GEL fibers had an average size of 1.0 ± 0.5 μm and a highly aligned fiber orientation, with chemical crosslinking and HEP conjugation reducing both fiber size and directionality due to the formation of interconnected networks. The crosslinking process proved to improve fiber stability in aqueous medium, allowing for >78% initial weight to be retained after 14 days. HEP conjugation yielded 15.3 ± 1.5 μg/mL per mg of fibers, with >91% HEP still covalently bound to PCL/GEL fibers after 14 days of incubation. PCL/GEL fibers significantly upregulated gene expression of tenogenic markers in amniotic epithelial cells (AECs) seeded on them for 48 hours, while HEP-conjugated fibers proved to possess an anti-inflammatory immunomodulatory activity on AECs.

In this work, the electrospinning technique was used to prepare novel polymeric composite fibers containing Te-doped bioactive glass powders. Bioactive glass powders containing tellurium (STe5 glass) were chosen as fillers for the composites, owing to their bioactive, antibacterial, and antioxidant properties. The biopolymer poly (ϵ-caprolactone) (PCL) and acetic acid (AA) were used as raw materials for the preparation of the polymeric matrix. FESEM analysis confirmed a good incorporation of the glass powders in the polymeric fibers, of up to 20% by weight. Wettability, mechanical, in vitro stability and preliminary antibacterial tests were also performed. The results showed that the treatment in AA did not affect the bioactivity of the glass powders, the presence of STe5 powders in PCL enhanced the wettability of the fibers, and mechanical properties improved by increasing the amount of STe5 powders, as well as the antibacterial effect. Therefore, the obtained materials appear promising for developing multifunctional composite materials for applications in tissue engineering.

The electrospinning technique is a commonly employed approach to fabricate fibers intended for various tissue engineering applications. The aim of this study is to develop a novel strategy for tendon repair through the use of aligned poly(ε‐caprolactone) (PCL) and poly(glycerol sebacate) (PGS) fibers fabricated in benign solvents, and further explore the potential application of PGS in tendon tissue engineering (TTE). The fibers were characterized for their morphological and physicochemical properties; amniotic epithelial stem cells (AECs) were used to assess the fibers teno‐inductive and immunomodulatory potential due to their ability to teno‐differentiate undergoing first a stepwise epithelial to mesenchymal transition, and due to their documented therapeutic role in tendon regeneration. The addition of PGS to PCL improved the spinnability of the polymer solution, as well as the uniformity and directionality of the so‐obtained fibers. The mechanical properties were in the range of most TTE applications, specifically in the case of PCL/PGS 4:1 and 2:1 ratios. Compared to PCL alone, the same ratios also allowed a better AECs infiltration and growth over 7 days of culture, and triggered the activation of tendon‐related genes (SCX, COL1, TNMD) and the expression of tenomodulin (TNMD) at the protein level. Concerning the immunomodulatory properties, both PCL and PCL/PGS fibers negatively affected the immunomodulatory profile of AECs, up‐regulating both anti‐inflammatory (IL‐10) and pro‐inflammatory (IL‐12) cytokines over 7 days of culture. Overall, PCL/PGS 2:1 fibers fabricated with benign solvents proved to be the most suitable composition for TTE application based on their topographical cues, mechanical properties, biocompatibility, and teno‐inductive properties.

This work demonstrates that scaffolds’ fiber alignment has an impact on the immune recognition of the scaffolds and presents TLR reporter cells as a simple and fast read out system for analyzing the recognition of the scaffolds by TLRs.

Aligned biodegradable fibers incorporating bioactive glass particles are being highly investigated for tissue engineering applications. In this study, 5, 7 and 10 wt% melt-derived 1393B3 borate glass (BG) microparticles (average size: 3.15 µm) were incorporated in 83 wt% polycaprolactone (PCL) and 17 wt% gelatin (GEL) (83PCL/17GEL) solutions to produce aligned electrospun composite nanofiber mats. Addition of 5 wt% BG particles significantly increased the alignment of the nanofibers. However, further incorporation of BG particles led to reduced degree of alignment, likely due to an increase of viscosity. Mechanical tests indicated a tensile modulus and tensile strength of approximately 51 MPa and 3.4 MPa, respectively, for 5 wt% addition of 1393B3 BG microparticles, values considered suitable for soft tissue engineering applications. However, with the increasing amount of 1393B3 BG, the nanofiber mats became brittle. Contact angle was reduced after the addition of 5 wt% of 1393B3 BG particles from ∼45° to ∼39°. Cell culture studies with normal human dermal fibroblast (NHDF) cells indicated that 5 wt% 1393B3 BG incorporated nanofiber mats were cytocompatible whereas higher doping with 1393B3 BGs reduced biocompatibility. Overall, 5 wt% 1393B3 BG doped PCL/GEL nanofiber mats were aligned with high biocompatibility exhibiting desirable mechanical properties for soft tissue engineering, which indicates their potential for applications requiring aligned nanofibers, such as peripheral neural regeneration.