Comparision of mechanical properites of biodegradable PCL-based binary and ternary composites

Celem poniższych badań było porównanie właściwości mechanicznych włókien kompozytów polimerowo-ceramicznych na osnowie polikaprolaktonu (PCL) jako potencjalnego materiału do wytworzenia rusztowań do regeneracji ubytków tkanki kostnej w organizmie człowieka. Jako napełniacz wykorzystano mikro-cząstki trójfosforanu wapnia (TCP). Wytworzono również kompozyt potrójny zawierający dodatkowo kopolimer kwasu mlekowego i glikolowego (PLGA). Przeprowadzono próbę rozciągania oraz obserwację na skaningowym mikroskopie elektronowym. Wprowadzenie mikrocząstek TCP do osnowy PCL tylko w małym stopniu poprawiło właściwości mechaniczne kompozytów. Dopiero dodatek PLGA spowodował znaczy wzrost sztywności oraz podwyższenie granicy plastyczności.The aim of present study was to compare the mechanical properties of binary and ternary composite fibers fabricated by means of combined solvent casting and fused deposition modeling techniques. The tested composites were composed of polycaprolactone (PCL) matrix and tricalcium (TCP) micro-particles (binary composite) and additionally poly(D,L-lactide- co-glycolide), PLGA, (ternary composite). TCP and PLGA were used as a reinforcement of the composites. Tensile test was conducted in order to determine the effect of TCP and PLGA on mechanical properties of the composites. Introduction to TCP particles had slight effect of the Young's modulus. However, addition of TCP and PLGA to PCL matrix significantly improved the mechanical properties of the ternary composite

Fabrication of porous poly (3-hydroxybutyrate- co-3-hydroxyvalerate) scaffolds using a rapid prototyping technique

Poli(3-hydroksymaślan-ko-3-hydroksywalerian) (PHBV) jest polimerem biodegradowalnym należącym do grupy poliestrów alifatycznych. Polimer ten jest termoplastem o wysokim wskaźniku szybkości płynięcia, co utrudnia jego przetwarzanie za pomocą wytłaczania. W przedstawionych badaniach wytworzono mieszankę PHBV z PLGA oraz wyznaczono jej masowy wskaźnik szybkości płynięcia (MFR). Dodatek PLGA obniżył MFR, co umożliwiło wytworzenie trójwymiarowego rusztowania za pomocą techniki szybkiego prototypowania.Poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a biodegradable polymer which belongs to a group of aliphatic polyesters. PHBV is a thermoplast with a relatively high melt flow index. This property makes it difficult to process by means of extrusion. In the present study we have prepared PHBV blended with PLGA and determined its melt flow rate (MFR). The addition of PLGA decreased MFR, which enabled fabrication of three-dimensional scaffold by means of Fused Deposition Modeling (FDM)

Three-dimensional imaging of bone scaffolds seeded with stem cells

W pierwszym etapie niniejszej pracy wytworzono i zasiedlono agregatami komórek macierzystych innowacyjne biomateriały. Rusztowania wykonano z mieszaniny poli(3-hydroksymaślanu-ko-3-hydroksywalerianu) (PHBV), poli(L-laktydu-ko-glikolidu) (PLGA) oraz trójfosforanu wapnia (TCP). W drugim etapie pracy, scharakteryzowano wytworzone biomateriały wykorzystując techniki rentgenowskiej mikrotomografii komputerowej z użyciem środka kontrastującego. Poddano je także analizie powierzchniowej przy pomocy mikroskopu sił atomowych. Wyniki odniesiono do materiału referencyjnego, którym były rusztowania wykonane z PHBV i PLGA. Mikrotomografia komputerowa zapewniła wnikliwą ocenę struktury rusztowań kostnych. Oprócz obrazowania komórek macierzystych umożliwiła obserwację mikrostruktury w całej objętości badanego materiału w 3D. Kolejną techniką szeroko stosowaną do badań rusztowań polimerowych była mikroskopia sił atomowych. Umożliwiła ona wizualną ocenę topografii badanych materiałów oraz analizę ich chropowatości. Wytworzone rusztowania kostne miały odpowiednie parametry dla proliferacji komórek macierzystych. Wyniki niniejszej pracy wykazały, że tomografia komputerowa jest odpowiednim narzędziem do obrazowania komórek macierzystych zasiedlonych na porowatych biomateriałach. Dodatkowo stwierdzono, że specjalnie modyfikowane sondy skanujące umożliwiły dokładniejszy w stosunku do standardowych pomiar chropowatości powierzchni rusztowań.The first stage of this study involved the preparation and seeding of innovative biomaterials with stem cell Scaffolds through a mixture of poly (3-hydroxybutyrate-co-3-hydroksy-valerat) (PHBV), poly (L-lactide-co-glycolide) (PLGA) and tricalcium phosphate (TCP). In the second stage, biomaterials were characterized using a X-ray computed microtomography (CT) with a contrast agent. They were also subjected to surface analysis using atomic force microscopy. The results were compared to the reference material, of a PHBV/PLGA composite scaffold. The computed microtomography ensured rigorous assessment of the bone scaffold structure. Apart from stem cell imaging it also enabled the observation of the microstructure in the entire volume of the material in 3D. Another technique used to study polymeric scaffold was atomic force microscopy (AFM). It allowed for the visual assessment of the topography of the tested materials, as well as the analysis of their surface roughness. The tested bone scaffolds showed appropriate parameters for stem cell proliferation. The results of this study indicated that tomography is a suitable tool for the imaging of stem cell seeding on porous biomaterials. In addition, we couclude that specially modified scanning probes enabled more accurate surface roughness measurements

Tailored degradation of biocompatible poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/calcium silicate/poly(lactide-co-glycolide) ternary composites: an in vitro study

Biodegradable materials, which are currently available for bone tissue regeneration, still have limitations regarding their degradation rate, mechanical stability and/or biological response. Thus, a novel generation of materials for bioactive bone scaffolds is needed that triggers hydroxyapatite formation and can be tailored to suit application-specific requirements. In this study we developed ternary bioactive composite materials composed of poly(3-hydroxybutyrate-co-3-hydroxyvalerate), calcium silicate and poly(lactide-co-glycolide) (PHBV/CS/PLGA), which merged the good bioactivity of CS/PHBV composite and the improved degradation velocity of PHBV/PLGA blend. Bioactive character of all composites was proven by formation of hydroxyapatite-like crystals after already one week of incubation in simulated body fluid. Addition of PLGA significantly increased initial ultimate tensile strength (UTS0) and Young's modulus of the ternary composites from 14.3 ± 1.1 MPa (binary composite) to 22.3 ± 2.6 MPa and 1.23 ± 0.05 GPa up to 1.64 ± 0.14 GPa, respectively. Furthermore the degradation rate (measured as a decrease of UTS during degradation) could be successfully tailored and was in range of − 0.033 UTS0 to − 0.118 UTS0 MPa/week. The bioacceptance of the materials was proven in vitro using 2-D (conventional setup) and 3-D (multicellular spheroids) human bone marrow stromal cell cultures

Post Processing and Biological Evaluation of the Titanium Scaffolds for Bone Tissue Engineering

Nowadays, post-surgical or post-accidental bone loss can be substituted by custom-made scaffolds fabricated by additive manufacturing (AM) methods from metallic powders. However, the partially melted powder particles must be removed in a post-process chemical treatment. The aim of this study was to investigate the effect of the chemical polishing with various acid baths on novel scaffolds’ morphology, porosity and mechanical properties. In the first stage, Magics software (Materialise NV, Leuven, Belgium) was used to design a porous scaffolds with pore size equal to (A) 200 µm, (B) 500 µm and (C) 200 + 500 µm, and diamond cell structure. The scaffolds were fabricated from commercially pure titanium powder (CP Ti) using a SLM50 3D printing machine (Realizer GmbH, Borchen, Germany). The selective laser melting (SLM) process was optimized and the laser beam energy density in range of 91–151 J/mm3 was applied to receive 3D structures with fully dense struts. To remove not fully melted titanium particles the scaffolds were chemically polished using various HF and HF-HNO3 acid solutions. Based on scaffolds mass loss and scanning electron (SEM) observations, baths which provided most uniform surface cleaning were proposed for each porosity. The pore and strut size after chemical treatments was calculated based on the micro-computed tomography (µ-CT) and SEM images. The mechanical tests showed that the treated scaffolds had Young’s modulus close to that of compact bone. Additionally, the effect of pore size of chemically polished scaffolds on cell retention, proliferation and differentiation was studied using human mesenchymal stem cells. Small pores yielded higher cell retention within the scaffolds, which then affected their growth. This shows that in vitro cell performance can be controlled to certain extent by varying pore sizes

3D Tissue Modelling of Skeletal Muscle Tissue

Skeletal muscle tissue exhibits endogenous ability to regenerate. However, the self-repair mechanism is restricted only to small damages. The increasing number of extensive injuries of skeletal muscles due to various accidents, more active life-style or cancer resection, combined with the shortcomings of the conventional treatment procedures, creates demand for new, more advanced solutions. Muscle tissue engineering (TE) appears as a promising strategy for fabrication of tissue substitutes from biomaterials, cells and bioactive factors, alone or combined. In this chapter, we present current state of the art of regeneration and engineering of skeletal muscle tissue. The chapter begins with a brief introduction to structure and functions of skeletal muscle tissue, followed by discussion of cells with potential for repair of muscle injuries and dysfunctions. Next, we provide an overview of natural and synthetic biomaterials used in skeletal muscle TE, as well as description of techniques used to process the biomaterials into scaffolds. We also highlight the importance of mechanical and electrical stimulation during in vitro culture and their effect on cell differentiation and maturation. Last but not least, the latest results of in vivo studies are reported. The chapter is concluded with a short summary and outlook on future developments

Irradiation with 365 nm and 405 nm wavelength shows differences in DNA damage of swine pancreatic islets.

Introduction3D printing is being used more extensively in modern biomedicine. One of the problems is selecting a proper crosslinking method of bioprinted material. Amongst currently used techniques we can distinguish: physical crosslinking (e.g. Ca2+ and Sr2+) and chemical crosslinking-the UV light crosslinking causing the biggest discussion. UV radiation is selectively absorbed by DNA, mainly in the UV-B region but also (to some extent) in UV-A and UV-C regions. DNA excitement results in typical photoproducts. The amount of strand breaks may vary depending on the period of exposition, it can also differ when cells undergo incubation after radiation.AimThe aim of this study was to show whether and how the time of irradiation with 405 nm and 365 nm wavelengths affect DNA damage in cell lines and micro-organs (pancreatic islets).Materials and methodsThe degree of DNA damage caused by different wavelengths of radiation (405 nm and 365 nm) was evaluated by a comet assay. The test was performed on fibroblasts, alpha cells, beta cells and porcine pancreatic islets after 24 hours incubation period. Samples without radiation treatment were selected as a control group. Results analysis consisted of determining the percent of cells with damaged DNA and the tail intensity evaluation.ResultsThe degree of DNA damage in pancreatic islets after exposure to 405 nm wavelength oscillated between 2% and 6% depending on the tested time period (10 - 300 seconds). However, treating islets using 365 nm wavelength resulted in damage up to 50%. This clearly shows significantly less damage when using 405 nm wavelength. Similar results were obtained for the tested cell lines.ConclusionsCrosslinking with 405 nm is better for pancreatic islets than crosslinking with 365 nm UV light