We draw the conclusion that all positive effects observed using the 3D PCL nanofibre scaffold are related to the larger fibre surface area available to the cells. Thus, the proposed 3D structure of the nanofibre layer will find a wide array of applications in tissue engineering and regenerative medicine.

No abstract

Incisional hernia affects up to 20% of patients after abdominal surgery. Unlike other types of hernia, its prognosis is poor, and patients suffer from recurrence within 10 years of the operation. Currently used hernia-repair meshes do not guarantee success, but only extend the recurrence-free period by about 5 years. Most of them are nonresorbable, and these implants can lead to many complications that are in some cases life-threatening. Electrospun nanofibers of various polymers have been used as tissue scaffolds and have been explored extensively in the last decade, due to their low cost and good biocompatibility. Their architecture mimics the natural extracellular matrix. We tested a biodegradable polyester poly-ε-caprolactone in the form of nanofibers as a scaffold for fascia healing in an abdominal closure-reinforcement model for prevention of incisional hernia formation. Both in vitro tests and an experiment on a rabbit model showed promising results.

A three-dimensional scaffold of type I collagen and hydroxyapatite enriched with polycaprolactone nanofibers (Coll/HA/PCL), autologous mesenchymal stem cells (MSCs) in osteogenic media, and thrombocyte-rich solution (TRS) was an optimal implant for bone regeneration in vivo in white rabbits. Nanofibers optimized the viscoelastic properties of the Coll/HA scaffold for bone regeneration. MSCs and TRS in the composite scaffold improved bone regeneration. Three types of Coll/HA/PCL scaffold were prepared: an MSC-enriched scaffold, a TRS-enriched scaffold, and a scaffold enriched with both MSCs and TRS. These scaffolds were implanted into femoral condyle defects 6 mm in diameter and 10-mm deep. Untreated defects were used as a control. Macroscopic and histological analyses of the regenerated tissue from all groups were performed 12 weeks after implantation. The highest volume and most uniform distribution of newly formed bone occurred in defects treated with scaffolds enriched with both MSCs and TRS compared with that in defects treated with scaffolds enriched by either component alone. The modulus of elasticity in compressive testing was significantly higher in the Coll/HA/PCL scaffold than those without nanofibers. The composite Coll scaffold functionalized with PCL nanofibers and enriched with MSCs and TRS appears to be a novel treatment for bone defects.

Collagen/hydroxyapatite (HA) composite scaffolds are known to be suitable scaffolds for seeding with mesenchymal stem cells (MSCs) differentiated into osteoblasts and for the in vitro production of artificial bones. However, the optimal collagen/HA ratio remains unclear. Our study confirmed that a higher collagen content increased scaffold stiffness but that a greater stiffness was not sufficient for bone tissue formation, a complex process evidently also dependent on scaffold porosity. We found that the scaffold pore diameter was dependent on the concentration of collagen and HA and that it could play a key role in cell seeding. In conclusion, the optimal scaffold for new bone formation and cell proliferation was found to be a composite scaffold formed from 50 wt % HA in 0.5 wt % collagen I solution.

Incisional hernia is the most common postoperative complication, affecting up to 20% of patients after abdominal surgery. Insertion of a synthetic surgical mesh has become the standard of care in ventral hernia repair. However, the implementation of a mesh does not reduce the risk of recurrence and the onset of hernia recurrence is only delayed by 2–3 years. Nowadays, more than 100 surgical meshes are available on the market, with polypropylene the most widely used for ventral hernia repair. Nonetheless, the ideal mesh does not exist yet; it still needs to be developed. Polycaprolactone nanofibers appear to be a suitable material for different kinds of cells, including fibroblasts, chondrocytes, and mesenchymal stem cells. The aim of the study reported here was to develop a functionalized scaffold for ventral hernia regeneration. We prepared a novel composite scaffold based on a polypropylene surgical mesh functionalized with poly-ε-caprolactone (PCL) nanofibers and adhered thrombocytes as a natural source of growth factors. In extensive in vitro tests, we proved the biocompatibility of PCL nanofibers with adhered thrombocytes deposited on a polypropylene mesh. Compared with polypropylene mesh alone, this composite scaffold provided better adhesion, growth, metabolic activity, proliferation, and viability of mouse fibroblasts in all tests and was even better than a polypropylene mesh functionalized with PCL nanofibers. The gradual release of growth factors from biocompatible nanofiber-modified scaffolds seems to be a promising approach in tissue engineering and regenerative medicine.

Additive manufacturing, also called 3D printing, is an effective method for preparing scaffolds with defined structure and porosity. The disadvantage of the technique is the excessive smoothness of the printed fibers, which does not support cell adhesion. In the present study, a 3D printed scaffold was combined with electrospun classic or structured nanofibers to promote cell adhesion. Structured nanofibers were used to improve the infiltration of cells into the scaffold. Electrospun layers were connected to 3D printed fibers by gluing, thus enabling the fabrication of scaffolds with unlimited thickness. The composite 3D printed/nanofibrous scaffolds were seeded with primary chondrocytes and tested in vitro for cell adhesion, proliferation and differentiation. The experiment showed excellent cell infiltration, viability, and good cell proliferation. On the other hand, partial chondrocyte dedifferentiation was shown. Other materials supporting chondrogenic differentiation will be investigated in future studies.

These simply functionalized scaffolds present new possibilities for nanofibre applications, as smart cell scaffolds equipped with a GF delivery tool.