Instytut Podstawowych Problemów Techniki

Streszczenie:

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.

Słowa kluczowe:

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

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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.

Słowa kluczowe:

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

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Streszczenie:

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.

Słowa kluczowe:

urinary bladder regeneration, electrospinning

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Streszczenie:

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.

Słowa kluczowe:

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

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Streszczenie:

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.

Słowa kluczowe:

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

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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.

Słowa kluczowe:

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

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Streszczenie:

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.

Słowa kluczowe:

Nanofibres for neurosurgery, protection of scar formation

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