Institute of Fundamental Technological Research

Wounds and chronic wounds can be caused by bacterial infections and lead to discomfort in patients. To solve this problem, scientists are working to create modern wound dressings with antibacterial additives, mainly because traditional materials cannot meet the general requirements for complex wounds and cannot promote wound healing. This demand is met by material engineering, through which we can create electrospun wound dressings. Electrospun wound dressings, as well as those based on hydrogels with incorporated antibacterial compounds, can meet these requirements. This manuscript reviews recent materials used as wound dressings, discussing their formation, application, and functionalization. The focus is on presenting dressings based on electrospun materials and hydrogels. In contrast, recent advancements in wound care have highlighted the potential of thermoresponsive hydrogels as dynamic and antibacterial wound dressings. These hydrogels contain adaptable polymers that offer targeted drug delivery and show promise in managing various wound types while addressing bacterial infections. In this way, the article is intended to serve as a compendium of knowledge for researchers, medical practitioners, and biomaterials engineers, providing up-to-date information on the state of the art, possibilities of innovative solutions, and potential challenges in the area of materials used in dressings.

wound dressings, drug delivery systems, thermoresponsive hydrogels

Bone repair and regeneration require physiological cues, including mechanical, electrical, and biochemical activity. Many biomaterials have been investigated as bioactive scaffolds with excellent electrical properties. Amongst biomaterials, piezoelectric materials (PMs) are gaining attention in biomedicine, power harvesting, biomedical devices, and structural health monitoring. PMs have unique properties, such as the ability to affect physiological movements and deliver electrical stimuli to damaged bone or cells without an external power source. The crucial bone property is its piezoelectricity. Bones can generate electrical charges and potential in response to mechanical stimuli, as they influence bone growth and regeneration. Piezoelectric materials respond to human microenvironment stimuli and are an important factor in bone regeneration and repair. This manuscript is an overview of the fundamentals of the materials generating the piezoelectric effect and their influence on bone repair and regeneration. This paper focuses on the state of the art of piezoelectric materials, such as polymers, ceramics, and composites, and their application in bone tissue engineering. We present important information from the point of view of bone tissue engineering. We highlight promising upcoming approaches and new generations of piezoelectric materials.

piezoelectricity, scaffolds, smart scaffolds, PVDF, PLLA, PVDF-TRFE, collagen, keratin, tissue engineering, bone tissue engineering, smart medicine, regenerative medicine

Bone tissue engineering using different scaffolds is a new therapeutic approach in regenerative medicine. This study explored the osteogenic potential of human dental pulp stem cells (hDPSCs) grown on a hydrolytically modified poly(L-lactide-co-caprolactone) (PLCL) electrospun scaffold and a non-woven hyaluronic acid (HYAFF-11™) mesh. The adhesion, immunophenotype, and osteogenic differentiation of hDPSCs seeded on PLCL and HYAFF-11™ scaffolds were analyzed. The results showed that PLCL and HYAFF-11™ scaffolds significantly supported hDPSCs adhesion; however, hDPSCs’ adhesion rate was significantly higher on PLCL than on HYAFF-11™. SEM analysis confirmed good adhesion of hDPSCs on both scaffolds before and after osteogenesis. Alizarin red S staining showed mineral deposits on both scaffolds after hDPSCs osteogenesis. The mRNA levels of runt-related transcription factor 2 (Runx2), collagen type I (Coll-I), osterix (Osx), osteocalcin (Ocn), osteopontin (Opn), bone sialoprotein (Bsp), and dentin sialophosphoprotein (Dspp) gene expression and their proteins were higher in hDPSCs after osteogenic differentiation on both scaffolds compared to undifferentiated hDPSCs on PLCL and HYAFF-11™. These results showed that PLCL scaffolds provide a better environment that supports hDPSCs attachment and osteogenic differentiation than HYAFF-11™. The high mRNA of early osteogenic gene expression and mineral deposits observed after hDPSCs osteogenesis on a PLCL mat indicated its better impact on hDPSCs’ osteogenic potential than that of HYAFF-11™, and hDPSC/PLCL constructs might be considered in the future as an innovative approach to bone defect repair.

dental stem cells, hDPSCs, osteogenesis, PLCL scaffold, HYAFF-11 scaffold

Aiming at biomedical applications, the present work developed a new bio-nanocomposite fibrous mat based on natural rubber (NR) reinforced with 45S5 bioglass particles (BG) and cellulose nanowhiskers (CNW), which reveals excellent mechanical properties, good biocompatibility and bioactivity properties. Analyses of the specimens were conducted by means of morphological observa-tions (SEM) and thermal analysis (TG/DTG), as well as mechanical tests used to verify the effect of the incorporation of BG particles and CNW on the ultimate properties of these flexible NR-CWN/BG fibrous membranes. An SEM analysis revealed that all filaments possessed a ribbon-like morphology, with increasing diameters as the BG concentration increased. This likely results from an increased viscosity of the solution used for fiber blowing. In comparison with neat NR fibrous mats, the ultimate mechanical properties of bio-nanocomposites were sig-nificantly improved due to the presence of CNW and BG particles dispersed in the NR matrix. According to the TG/DTG analysis, the specimens' thermal stability was unaffected by the high BG content, and the thermal profiles were similar, with isoprene chains decomposition of the NR occurring between 350 and 450°C. In-vitro analysis on fibroblasts confirmed that the bio-nanocomposite fibrous mats are noncytotoxic. It was found that fibrous mats enhanced cellular growth and hold great promise for tissue engineering applications.

bioactive particles,cellulose nanowhiskers,fibrous mat bio-nanocomposite,natural rubber

The solution blow spinning technique was used to fabricate a new biocomposite fibrous mat consisting of natural rubber (NR) and polyhydroxybutyrate (PHB) bioblend, with various loads of 45S5 bioglass (BG) particles. According to SEM analysis, NR fibers exhibited ribbon-like morphologies, whereas the addition of PHB resulted in improved fiber formation and a reduction in their diameter. In NR-PHB/BG biocomposites with varying BG loadings, typical thermal degradation events of PHB (stage i) and NR (stage ii) were observed. In comparison with pure PHB, the TG/DTG curves of NR-PHB/BG specimens revealed a lower stage i degradation peak. Such an outcome is possibly due to the fact that PHB in the NR-PHB fibers is located predominantly at the surface, that is, PHB is more susceptible to thermal degradation. The NR-PHB/BG biocomposite possessed an increased stiffness due to the addition of PHB and BG, resulting in an increased stress and a decreased strain at rupture compared to the pure NR and NR-PHB mats. DMA analysis revealed two well-defined regions, above and below the glass transition temperature (Tg), for the storage modulus (E') of the NR-PHB/BG specimens. The values of E' were in both regions for NR-PHB/BG specimens increased at higher BG content. The measured tanδ = E″/E' was used to determine the Tg value for all specimens, with Tg found to be in the −49 to −46°C range. Finally, NR-PHB/BG biocomposite fibrous were proven noncytotoxic by in-vitro testing on fibroblasts. These biocomposites enhanced cell growth, holding great promise for tissue engineering applications.

45S5 bioglass, biocomposite fibrous mat, biomedical applications, natural rubber, polyhydroxybutyrate, solution blow spinning

Poly(l-lactide-co-caprolactone) (PLCL) electrospun scaffolds with seeded stem cells have drawn great interest in tissue engineering. This study investigated the biological behavior of human dental pulp stem cells (hDPSCs) grown on a hydrolytically-modified PLCL nanofiber scaffold. The hDPSCs were seeded on PLCL, and their biological features such as viability, proliferation, adhesion, population doubling time, the immunophenotype of hDPSCs and osteogenic differentiation capacity were evaluated on scaffolds. The results showed that the PLCL scaffold significantly supported hDPSC viability/proliferation. The hDPSCs adhesion rate and spreading onto PLCL increased with time of culture. hDPSCs were able to migrate inside the PLCL electrospun scaffold after 7 days of seeding. No differences in morphology and immunophenotype of hDPSCs grown on PLCL and in flasks were observed. The mRNA levels of bone-related genes and their proteins were significantly higher in hDPSCs after osteogenic differentiation on PLCL compared with undifferentiated hDPSCs on PLCL. These results showed that the mechanical properties of a modified PLCL mat provide an appropriate environment that supports hDPSCs attachment, proliferation, migration and their osteogenic differentiation on the PLCL scaffold. The good PLCL biocompatibility with dental pulp stem cells indicates that this mat may be applied in designing a bioactive hDPSCs/PLCL construct for bone tissue engineering.

hDPSCs, poly(l-lactide-co-caprolactone), electrospun scaffold, biocompatibility, adhesion, proliferation, osteogenic differentiation, tissue engineering

Electrospun hybrid nanofibers, based on functional agents immobilized in polymeric matrix, possess a unique combination of collective properties. These are beneficial for a wide range of applications, which include theranostics, filtration, catalysis, and tissue engineering, among others. The combination of functional agents in a nanofiber matrix offer accessibility to multifunctional nanocompartments with significantly improved mechanical, electrical, and chemical properties, along with better biocompatibility and biodegradability. This review summarizes recent work performed for the fabrication, characterization, and optimization of different hybrid nanofibers containing varieties of functional agents, such as laser ablated inorganic nanoparticles (NPs), which include, for instance, gold nanoparticles (Au NPs) and titanium nitride nanoparticles (TiNPs), perovskites, drugs, growth factors, and smart, inorganic polymers. Biocompatible and biodegradable polymers such as chitosan, cellulose, and polycaprolactone are very promising macromolecules as a nanofiber matrix for immobilizing such functional agents. The assimilation of such polymeric matrices with functional agents that possess wide varieties of characteristics require a modified approach towards electrospinning techniques such as coelectrospinning and template spinning. Additional focus within this review is devoted to the state of the art for the implementations of these approaches as viable options for the achievement of multifunctional hybrid nanofibers. Finally, recent advances and challenges, in particular, mass fabrication and prospects of hybrid nanofibers for tissue engineering and biomedical applications have been summarized.

hybrid nanofibers, electrospinning, nanoparticles, functional agents, tissue engineering, nanomedicine, drug delivery, bone regeneration

Micro- and nanofibers are historically-known materials that are continuously reinvented due to their valuable properties. They display promise for applications in many fields, from tissue engineering to catalysis or sensors. In the first application, micro- and nanofibers are mainly produced from a limited library of biomaterials with properties that need alteration before use. Post-modification is a very effective method for attaining on-demand features and functions of nonwovens. This review summarizes and presents methods of functionalization of nonwovens produced by electrostatic means. The reviewed modifications are grouped into physical methods, chemical modification, and mixed methods.

nanofiber post-modification, functional nanofibers, tissue engineering

Przedstawiono metodę modyfikacji żywic epoksydowych biscyklicznymi węglanami sześcioczłonowymi. Wykazano, że katalizowana kwasami Lewisa reakcja oksiranów z sześcioczłonowymi węglanami cyklicznymi przebiega głównie z wytworzeniem spiroortowęglanu pięcio-sześcioczłonowego. W jej wyniku powstają poli(etero-węglany), polietery i pięcioczłonowe węglany cykliczne. W niskiej temperaturze reakcja może ulec zahamowaniu na etapie spiroortowęglanu. Wykazano, że żywice epoksydowe zmodyfikowane dodatkiem 10 % mas. oligomeru uretanowego, zakończonego sześcioczłonowymi cyklicznymi węglanami lub biscyklicznym węglanem zawierającym resztę glikolu tri(oksyetylenowego), charakteryzują się udarnością o 66–83 % większą niż żywica niemodyfikowana, przy zachowanym poziomie wartości pozostałych cech wytrzymałościowych.

biscykliczne węglany sześcioczłonowe, modyfikacja żywicy epoksydowej, cykliczny węglan jako aktywny rozcieńczalnik, kationowa kopolimeryzacja oksiranów z sześcioczłonowymi cyklicznymi węglanami, polimeryzacja z otwarciem pierścienia

BACKGROUND: Electrospun nanofibers have widespread putative applications in the field of regenerative medicine and tissue engineering. When compared to naturally occurring collagen matrices, electrospun nanofiber scaffolds have two distinct advantages: they do not induce a foreign body reaction and they are not at risk for biological contamination. However, the exact substrate, structure, and production methods have yet to be defined. MATERIAL AND METHODS: In the current study, tubular-shaped poly(L-lactide-co-caprolactone) (PLCL) constructs produced using electrospinning technology were evaluated for their potential application in the field of tissue regeneration in two separate anatomic locations: the skin and the abdomen. The constructs were designed to have an internal diameter of 3 mm and thickness of 200 μm. Using a rodent model, 20 PLCL tubular constructs were surgically implanted in the abdominal cavity and subcutaneously. The constructs were then evaluated histologically using electron microscopy at 6 weeks post-implantation. RESULTS: Histological evaluation and analysis using scanning electron microscopy showed that pure scaffolds by themselves were able to induce angiogenesis after implantation in the rat model. Vascularization was observed in both tested groups; however, better results were obtained after intraperitoneal implantation. Formation of more and larger vessels that migrated inside the scaffold was observed after implantation into the peritoneum. In this group no evidence of inflammation and better integration of scaffold with host tissue were noticed. Subcutaneous implantation resulted in more fibrotic reaction, and differences in cell morphology were also observed between the two tested groups. CONCLUSIONS: This study provides a standardized evaluation of a PLCL conduit structure in two different anatomic locations, demonstrating the excellent ability of the structure to achieve vascularization. Functional, histological, and mechanical data clearly indicate prospective clinical utilization of PLCL in critical size defect regeneration.

Polymers, Regenerative medicine, Tissue Engineering, Tissue Scaffolds, Urinary Diversion

Objective
Due to the capacity of the amniotic membrane (Am) to support re-epithelisation and inhibit scar formation, Am has a potential to become a considerable asset for reconstructive urology i.e., reconstruction of ureters and urethrae. The application of Am in reconstructive urology is limited due to a poor mechanical characteristic. Am reinforcement with electrospun nanofibers offers a new strategy to improve Am mechanical resistance, without affecting its unique bioactivity profile. This study evaluated biocomposite material composed of Am and nanofibers as a graft for urinary bladder augmentation in a rat model.

Material and Methods
Sandwich-structured biocomposite material was constructed from frozen Am and covered on both sides with two-layered membranes prepared from electrospun poly-(L-lactide-co-E-caprolactone) (PLCL). Wistar rats underwent hemicystectomy and bladder augmentation with the biocomposite material.

Results
Immunohistohemical analysis (hematoxylin and eosin [H&E], anti-smoothelin and Masson’s trichrome staining [TRI]) revealed effective regeneration of the urothelial and smooth muscle layers. Anti-smoothelin staining confirmed the presence of contractile smooth muscle within a new bladder wall. Sandwich-structured biocomposite graft material was designed to regenerate the urinary bladder wall, fulfilling the requirements for normal bladder tension, contraction, elasticity and compliance. Mechanical evaluation of regenerated bladder wall conducted based on Young’s elastic modulus reflected changes in the histological remodeling of the augmented part of the bladder. The structure of the biocomposite material made it possible to deliver an intact Am to the area for regeneration. An unmodified Am surface supported regeneration of the urinary bladder wall and the PLCL membranes did not disturb the regeneration process.

Conclusions
Am reinforcement with electrospun nanofibers offers a new strategy to improve Am mechanical resistance without affecting its unique bioactivity profile.

Bladder, Smooth muscles, Muscle regeneration, Bionanotechnology, Renal system, Urothelium, Urology, Nanomaterials

Albumin is rarely used for electrospinning because it does not form fibres in its native globular form. This paper presents a novel method for electrospinning human albumin from a solution containing pharmaceutical grade protein and 25% polyethylene oxide (PEO) used as the fibre-forming agent. After spontaneous cross-linking at body temperature, with no further chemicals added, the fibres become insoluble and the excess PEO can be washed out. Albumin deposited along the fibres retains its native characteristics, such as its non-adhesiveness to cells and its susceptibility for degradation by macrophages. To demonstrate this we evaluated the mechanical properties, biocompatibility and biodegradability of this novel product. After subcutaneous implantation in mice, albumin mats were completely resorbable within six days and elicited only a limited local inflammatory response. In vitro, the mats suppressed cell attachment and migration. As this product is inexpensive, produced from human pharmaceutical grade albumin without chemical modifications, retains its native protein properties and fulfils the specific requirements for anti-adhesive dressings, its clinical use can be expedited. We believe that it could specifically be used when treating paediatric patients with epidermolysis bullosa, in whom non-healing wounds occur after minor hand injuries which lead to rapid adhesions and devastating contractures.

albumin, nanofibers, wound dressing, biocompatibility, bioresorption

Drug delivery systems based on nanofibrous mats appear to be a promising healing practice for preventing brain neurodegeneration after surgery. One of the problems encountered during planning and constructing optimal delivery system based on nanofibrous mats is the estimation of parameters crucial for predicting drug release dynamics. This study describes our experimental setup allowing for spatial and temporary evaluation of drug release from nanofibrous polymers to obtain data necessary to validate appropriate numerical models. We applied laser light sheet method to illuminate released fluorescent drug analog and CCD camera for imaging selected cross-section of the investigated volume. Transparent hydrogel was used as a brain tissue phantom. The proposed setup allows for continuous observation of drug analog (fluorescent dye) diffusion for time span of several weeks. Images captured at selected time intervals were processed to determine concentration profiles and drug release kinetics. We used presented method to evaluate drug release from several polymers to validate numerical model used for optimizing nanofiber system for neuroprotective dressing.

neural therapy, brain phantom, drug delivery, laser light sheet, computational modeling, nanofibers

The purpose of this study was to compare: a new five-layered poly (L–lactide–co–caprolactone) (PLC) membrane and small intestinal submucosa (SIS) as a control in rat urinary bladder wall regeneration. The five-layered poly (L–lactide–co–caprolactone) membrane was prepared by an electrospinning process. Adipose tissue was harvested from five 8-week old male Wistar rats. Adipose derived stem cells (ADSCs) were seeded in a density of 3×106 cells/cm2 onto PLC membrane and SIS scaffolds, and cultured for 5-7 days in the stem cell culture medium. Twenty male Wistar rats were randomly divided into five equal groups. Augmentation cystoplasty was performed in a previously created dome defect. Groups: (I) PLC+ 3×106ADSCs; (II) SIS+ 3×106ADSCs; (III) PLC; (IV) SIS; (V) control. Cystography was performed after three months. The reconstructed urinary bladders were evaluated in H&E and Masson's trichrome staining. Regeneration of all components of the normal urinary bladder wall was observed in bladders augmented with cell-seeded SIS matrices. The urinary bladders augmented with SIS matrices without cells showed fibrosis and graft contraction. Bladder augmentation with the PLC membrane led to numerous undesirable events including: bladder wall perforation, fistula or diverticula formation, and incorporation of the reconstructed wall into the bladder lumen. The new five-layered poly (L–lactide–co–caprolactone) membrane possesses poorer potential for regenerating the urinary bladder wall compared with SIS scaffold.

urinary bladder regeneration, electrospinning

The aim of this study was to compare two different acellular scaffolds: natural and synthetic, for urinary conduit construction and ureter segment reconstruction. Acellular aortic arch (AAM) and poly(L-lactide-co-caprolactone) (PLCL) were used in 24 rats for ureter reconstruction in both tested groups. Follow-up period was 4 weeks. Intravenous pyelography, histological and immunohistochemical analysis were performed. All animals survived surgical procedures. Patent uretero-conduit junction was observed only in one case using PLCL. In case of ureter segment reconstruction ureters were patent in one case using AAM and in four cases using PLCL scaffolds. Regeneration of urothelium layer and focal regeneration of smooth muscle layer was observed on both tested scaffolds. Obtained results indicates that synthetic acellular PLCL scaffolds showed better properties for ureter reconstruction than naturally derived acellular aortic arch.

Ureter, Muscle regeneration, Kidneys, Collagens, Urine, Surgical and invasive medical procedures, Smooth muscles, Inflammation

The study was conducted to evaluate the cytocompatibility and hydrolytic degradability of the new poly(lactic acid)/polyethylene glycol-polyhedral oligomeric silsesquioxane (peg-POSS/PLLA) nanocomposite as potential material for cartilage regeneration. PLLA scaffolds containing 0 to 5% of peg-POSS were fabricated by electrospinning. Human mesenchymal stem cells (hMSC’s) were cultured in vitro to evaluate the cytocompatibility of the new nanocomposite material. Hydrolytic degradation studies were also carried out to analyze the mass loss rate of the nanocomposites through time. The addition of the peg-POSS to the PLLA did not affect the processability of the nanocomposite by electrospinning. It was also observed that peg-POSS did not show any relevant change in fibers morphology, concluding that it was well dispersed. However, addition of peg-POSS caused noticeable decrease in mean fiber diameter, which made the specific surface area of the scaffold to rise. hMSC’s were able to attach, to proliferate, and to differentiate into chondrocytes in a similar way onto the different types of electrospun peg-POSS/PLLA and pure PLLA scaffolds, showing that the peg-POSS as nano-additive does not exhibit any cytotoxicity. The hydrolytic degradation rate of the material was lower when peg-POSS was added, showing a higher durability of the nanocomposites through time. Results demonstrate that the addition of peg-POSS to the PLLA scaffolds does not affect its cytocompatibility to obtain hyaline cartilage from hMSC’s.

PLLA, peg-POSS, nanocomposite, electrospinning, chondrocyte, stem cells, scaffold, cartilage repair, hydrolytic degradation

Traumatic/surgical brain injury can initiate a cascade of pathological changes that result, in the long run, in severe damage of brain parenchyma and encephalopathy. Excessive scarring can also interfere with brain function and the glial scar formed may hamper the restoration of damaged brain neural pathways. In this preliminary study we aimed to investigate the effect of dressing with an L-lactide-caprolactone copolymer nanofiber net on brain wound healing and the fate of the formed glial scar. Our rat model of surgical brain injury (SBI) of the fronto-temporal region of the sensorimotor cortex imitates well the respective human neurosurgery situation. Brains derived from SBI rats with net-undressed wound showed massive neurodegeneration, entry of systemic inflammatory cells into the brain parenchyma and the astrogliosis due to massive glial scar formation. Dressing of the wound with the nanofiber net delayed and reduced the destructive phenomena. We observed also a reduction in the scar thickness. The observed modification of local inflammation and cicatrization suggest that nanofiber nets could be useful in human neurosurgery.

brain injury, L-lactide-caprolactone copolymer nanofiber net, glial scar, neurodegeneration

Large ureter damages are difficult to reconstruct. Current techniques are complicated, difficult to perform, and often associated with failures. The ureter has never been regenerated thus far. Therefore the use of tissue engineering techniques for ureter reconstruction and regeneration seems to be a promising way to resolve these problems. For proper ureter regeneration the following problems must be considered: the physiological aspects of the tissue, the type and shape of the scaffold, the type of cells, and the specific environment (urine). 
This review presents tissue engineering achievements in the field of ureter regeneration focusing on the scaffold, the cells, and ureter healing.

Excessive cicatrisation or epidural fibrosis in the operative field is an inappropriate event occasionally occurring after neurosurgical procedures (i.e., spine procedures and craniotomies). This excessive process may disturb the postopera­tive course and render reoperations more difficult and risky. The literature describes this phenomenon as accompanying up to 20% of neurosurgical procedures. The scar tissue that forms postoperatively adheres to the dura mater, penetrates into the spinal canal and can cause narrowing symptoms, neurological deficits and pain. The incidence and spread of this excessive scar or epidural fibrosis can be prevented through the modification of the surgical technique by incorporating endoscopic or microscopic access to minimize the operative field and the use of isolating substances (autogenous or heterogeneous) administered intraoperatively.

The aim of this experimental study was to morphologically assess the cicatrisation process, adhesion and to prevent excessive scar formation with the local use of membranes manufactured by an electrospinning process (nanotechnology). We also investigated whether the biodegradable nanofibrous net triggers or modifies the immunological response or the local inflammatory process.

Micro-nanofibrous membranes were produced by the electrospinning process. A biodegradable, medically certified copolymer poly(L-lactide-co-caprolactone) (PLCL) was used as the electrospun material.

An experimental rat model was used in this study. Experimental and control groups were formed with specified follow-up times of 4, 14 and 30 days. During the operation, a two-level laminectomy in the thoracic segment was performed. The operative field was divided into two regions. Isolating material was used on the dura mater and surface of the spinal cord in the area where the laminectomy was performed. The material was analysed with the use of light and electron microscopy.

Local cicatrisation can be modified using nanomaterials. Scar formation and epidural fibrosis can be limited and modi­fied locally. No local inflammation process was observed.

Initial observations indicate the potential for the effective use of materials obtained in the electrospinning process to prevent cicatrisation.

neurosurgery, cicatrisation, epidural fibrosis, copolymer, poly(L-lactide-co-caprolactone), nanofibrous net, rat model

Introduction.
Tissue engineering and biomaterials science currently offer the technology needed to replace the urinary tract wall. This review addresses current achievements and barriers for the regeneration of the urinary bladder based on tissue engineering methods. Materials and methods. Medline was search for urinary bladder tissue engineering regenerative medicine and stem cells.

Results.
Numerous studies to develop a substitute for the native urinary bladder wall using the tissue engineering approach are ongoing. Stem cells combined with biomaterials open new treatment methods, including even de novo urinary bladder construction. However, there are still many issues before advances in tissue engineering can be introduced for clinical application.

Conclusions.
Before tissue engineering techniques could be recognize as effective and safe for patients, more research studies performed on large animal models and with long follow–up are needed to carry on in the future.

stem cells, bladder regeneration, tissue engineering

Electrospun nonwovens have recently been successfully applied as a dressing material in spinal neurosurgery. Scarring is known to be one of the major post-operative complications for neurosurgery. If it occurs, it may trap a nerve, so that when a patient moves the nerve becomes stretched, causing nerve damage, pain, and internal scarring of the nerve. This causes subsequent complications related to ingrowths of connective tissue onto the spinal canal. The formation of an astroglial scar is another serious postoperative complication of brain neuro-surgery. The use of bio-absorbable isolative materials as anti-liaison protection and as possible carriers for neuroprotective drug delivery is expected to help in solving such problems. The nanostructured material acts as an anti-bacterial and anti-liaison barrier while enabling transport of oxygen, nutrients, and metabolites, facilitating the healing process of the surgical wound.

Nanofibres for neurosurgery, protection of scar formation

Biodegradable polymeric nanofibrous coatings were obtained by electrospinning different polymers onto sintered 45S5 Bioglass®-based glass-ceramic pellets. The investigated polymers were poly(3-hydroxybutyrate) (P3HB), poly(3-hydroxybutyrate-co-hydroxyvalerate) (PHBV) and a composite of poly(caprolactone) (PCL) and poly(ethylene oxide) (PEO) (PCL–PEO). The fibrous coatings morphology was evaluated by optical microscopy and scanning electron microscopy. The electrospinning process parameters were optimised to obtain reproducible coatings formed by a thin web of polymer nanofibres. In-vitro studies in simulated body fluid (SBF) were performed to investigate the bioactivity and mineralisation of the substrates by inducing the formation of hydroxyapatite (HA) on the nanofiber-coated pellets. HA crystals were detected on all samples after 7 days of immersion in SBF, however the morphology of the HA layer depended on the characteristic fibre diameter, which in turn was a function of the specific polymer-solvent system used. The bioactive and resorbable nanofibrous coatings can be used to tailor the surface topography of bioactive glass-ceramics for applications in tissue engineering scaffolds.

Electrospinning, Nanofibers, Bioglass®, Polyhydroxyalkanoates, Tissue engineering

Electrospinning of the globular protein, bovine serum albumin (BSA), was optimized to obtain proteinous fibers suitable asbiosensors. It was shown that the as-spun protein preserves its native form, whereas solubility of the cross-linked in the ambient conditions BSA nanofibers evidently decreases. Insoluble BSA fibers can be easily modified to be used as two-dimensional biosensors. Here, we show the micro pH sensor obtained from the BSA fiber stained with a fluorescein derivative (FITC).

Electrospinning BSA, pH sensor

Comprehensive studies of drug transport in nanofibres based mats have been performed to predict drug release kinetics. The paper presents our approach to analyze the impact of fibers arrangement, one of the parameters varied in our parallel experimental studies. Drug encapsulation in submicron fibers and subsequent controlled release of drugs is a tedious task due to the large number of process and material parameters involved. In the numerical study we constructed a 3D finite element geometry representing nanofibrous cubic element. COMSOL Multiphysics has been used to assess the impact of the various purposed arrangements of fibers within the mat. Drug release from nanofibers was modeled by adsorption -desorption and diffusion equation, where drug diffusion coefficient in the fluid between the fibers was altered depending on porosity of the material. Our study shows that for the same material porosity drug release from the matrix of regularly oriented fibers is slower than from randomly oriented, isotropic nanofibrous material. Also by decreasing distance between the fibers drug transport rate is reduced.

Nanofibres, finite elements, drug release modelling

A fast discrete model for the simulations of thin charged jets produced during the electrospinning process is derived, based on an efficient implementation of the boundary element method for the computation of electrostatic interactions of the jet with itself and with the electrodes. Short-range electrostatic forces are evaluated with slender-body analytical approximations, whereas a hierarchical force evaluation algorithm is used for long-range interactions. Qualitative comparisons with experiments is discussed.

modelling electrospinning, electrostatic interactions, BEM

electrospinning, microfibers, nanofibers, in vivo, animal model

elektroprzędzenie, nanowłókna, uwalnianie leków, TBI

brain, drug delivery, nanofibres, mathematical modelling