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.

Fibrous scaffolds are desired in tissue engineering applications for their ability to mimic extracellular matrix. In this study we compared fibrous scaffolds prepared from polycaprolactone using three different fabrication methods, electrospinning (ES), electro-blowing and melt-blown combined with ES. Scaffolds differed in morphology, fiber diameters and pore sizes. Mesenchymal stem cell adhesion, proliferation and osteogenic differentiation on scaffolds was evaluated. The most promising scaffold was shown to be melt-blown in combination with ES which combined properties of both technologies. Microfibers enabled good cell infiltration and nanofibers enhanced cell adhesion. This scaffold was used for further testing in critical sized defects in rabbits. New bone tissue formation occurred from the side of the treated defects, compared to a control group where only fat tissue was present. Polycaprolactone fibrous scaffold prepared using a combination of melt-blown and ES technology seems to be promising for bone regeneration. The practical application of results is connected with enormous production capacity and low cost of materials produced by melt-blown technology, compared to other bone scaffold fabrication methods.

The study involved the electrospinning of the copolymer poly(L-lactide-co-ε-caprolactone) (PLCL) into tubular grafts. The subsequent material characterization, including micro-computed tomography analysis, revealed a level of porosity of around 70%, with pore sizes of 9.34 ± 0.19 μm and fiber diameters of 5.58 ± 0.10 μm. Unlike fibrous polycaprolactone, the electrospun PLCL copolymer promoted fibroblast and endothelial cell adhesion and proliferation in vitro. Moreover, the regeneration of the vessel wall was detected following implantation and, after six months, the endothelialization of the lumen and the infiltration of arranged smooth muscle cells producing collagen was observed. However, the degradation rate was found to be accelerated in the rabbit animal model. The study was conducted under conditions that reflected the clinical requirements-the prostheses were sutured in the end-to-side fashion and the long-term end point of prosthesis healing was assessed. The regeneration of the vessel wall in terms of endothelialization, smooth cell infiltration and the presence of collagen fibers was observed after six months in vivo. A part of the grafts failed due to the rapid degradation rate of the PLCL copolymer.

Stroke is despite of progressive improvements in treatment and reperfusion strategies one of the most devastating human pathology. However, as quality of acute health care improves and more people survive ischemic attack, healthcare specialists have to solve new challenges to preserve reasonable quality of life to these patients. Thus, novel approaches which prevents comorbidities of stroke and improve quality of life of stroke survivors in general has to be developed and experimentally tested. The aim of the present paper was to establish reliable rat model of middle cerebral occlusion and set of methods allowing selection of animals suitable for long-term experiments. We have compared mortality rates, cerebral blood flow and extension of ischemic lesion induced by intraluminal filament in three widely used outbred rat strains. We have additionally used an animal 18F-DG PET scans to verify its reliability in noninvasive detection of ischemic infarct in acute period (24 h after MCAO) for selecting animals eligible for long survival experiments. Our data clearly indicates that high variability between rat strains might negatively influence stroke induction by intraluminal thread occlusion of middle cerebral artery. Most reliable outbred rat strain in our hands was Sprague-Dawley where maximal reduction of cerebral blood flow and extensive ischemic lesion was observed. Contrary, Wistar rats exhibited higher mortality and Long-Evans rats significantly smaller or no ischemic region in comparison to Sprague-Dawley. Additionally, we have confirmed a positron emission tomography with 18F-fluorodeoxyglucose as suitable method to assess extension of ischemic region in acute period after the experimental arterial occlusion in rats.

Aim: This study evaluates the effect of electrospun dressings in critical sized full-thickness skin defects in rabbits. Materials & methods: Electrospun poly-ε-caprolactone (PCL) and polyvinyl alcohol (PVA) nanofibers were tested in vitro and in vivo. Results: The PCL scaffold supported the proliferation of mesenchymal stem cells, fibroblasts and keratinocytes. The PVA scaffold showed significant swelling, high elongation capacity, limited protein adsorption and stimulation of cells. Nanofibrous dressings improved wound healing compared with the control group in vivo. A change of the PCL dressing every 7 days resulted in a decreased epithelial thickness and type I collagen level in the adhesive group, indicating peeling off of the newly formed tissue. In the PVA dressings, the exchange did not affect healing. Conclusion: The results demonstrate the importance of proper dressing exchange.

The present study investigates the effect of an oxidized nanocrystalline diamond (O-NCD) coating functionalized with bone morphogenetic protein 7 (BMP-7) on human osteoblast maturation and extracellular matrix mineralization in vitro and on new bone formation in vivo. The chemical structure and the morphology of the NCD coating and the adhesion, thickness and morphology of the superimposed BMP-7 layer have also been assessed. The material analysis proved synthesis of a conformal diamond coating with a fine nanostructured morphology on the Ti6Al4V samples. The homogeneous nanostructured layer of BMP-7 on the NCD coating created by a physisorption method was confirmed by AFM. The osteogenic maturation of hFOB 1.19 cells in vitro was only slightly enhanced by the O-NCD coating alone without any increase in the mineralization of the matrix. Functionalization of the coating with BMP-7 resulted in more pronounced cell osteogenic maturation and increased extracellular matrix mineralization. Similar results were obtained in vivo from micro-CT and histological analyses of rabbit distal femurs with screws implanted for 4 or 12 weeks. While the O-NCD-coated implants alone promoted greater thickness of newly-formed bone in direct contact with the implant surface than the bare material, a further increase was induced by BMP-7. It can be therefore concluded that O-NCD coating functionalized with BMP-7 is a promising surface modification of metallic bone implants in order to improve their osseointegration.