Degradation, Bioactivity, and Osteogenic Potential of Composites Made of PLGA and Two Different Sol–Gel Bioactive Glasses

We have developed poly(l-lactide-co-glycolide) (PLGA) based composites using sol–gel derived bioactive glasses (S-BG), previously described by our group, as composite components. Two different composite types were manufactured that contained either S2—high content silica S-BG, or A2—high content lime S-BG. The composites were evaluated in the form of sheets and 3D scaffolds. Sheets containing 12, 21, and 33 vol.% of each bioactive glass were characterized for mechanical properties, wettability, hydrolytic degradation, and surface bioactivity. Sheets containing A2 S-BG rapidly formed a hydroxyapatite surface layer after incubation in simulated body fluid. The incorporation of either S-BG increased the tensile strength and Young’s modulus of the composites and tailored their degradation rates compared to starting compounds. Sheets and 3D scaffolds were evaluated for their ability to support growth of human bone marrow cells (BMC) and MG-63 cells, respectively. Cells were grown in non-differentiating, osteogenic or osteoclast-inducing conditions. Osteogenesis was induced with either recombinant human BMP-2 or dexamethasone, and osteoclast formation with M-CSF. BMC viability was lower at higher S-BG content, though specific ALP/cell was significantly higher on PLGA/A2-33 composites. Composites containing S2 S-BG enhanced calcification of extracellular matrix by BMC, whereas incorporation of A2 S-BG in the composites promoted osteoclast formation from BMC. MG-63 osteoblast-like cells seeded in porous scaffolds containing S2 maintained viability and secreted collagen and calcium throughout the scaffolds. Overall, the presented data show functional versatility of the composites studied and indicate their potential to design a wide variety of implant materials differing in physico-chemical properties and biological applications. We propose these sol–gel derived bioactive glass–PLGA composites may prove excellent potential orthopedic and dental biomaterials supporting bone formation and remodeling

Selected methods of preparation of porous scaffolds for tissue engineering

Inżynieria tkankowa jest interdyscyplinarną dziedziną, której celem jest opracowanie biologicznych substytutów umożliwiających regenerację lub zastąpienie uszkodzonych lub zmienionych chorobowo tkanek czy organów. Dąży się do tego, aby rusztowania tkankowe posiadały wymagane korzystne cechy oraz spełniały przynajmniej niektóre funkcje naturalnej macierzy zewnątrzkomórkowej. Jednym z najważniejszych etapów opracowania podłoży jest projektowanie i wytwarzanie przestrzennej, wysoko porowatej struktury o pożądanym kształcie i rozmiarze porów. W niniejszym opracowaniu przedstawiono stan wiedzy na temat najpopular-niejszych metod wytwarzania przestrzennych rusztowań w inżynierii tkankowej, do których należą: odlewanie z roztworu z wymywaniem porogenu, termicznie indukowana separacja faz oraz separacja faz w układzie rozpuszczalnik–nierozpuszczalnik.Tissue engineering is an interdisciplinary field aiming to develop of biological substitutes, that are able to regenerate or replace damaged or diseased tissues or organs. The approach to tissue engineering is to use scaffolds that mimics multiple advantageous characteristics of the native extracellular matrix. One of the most important stages of building scaffolds is the design and preparation of a porous, three-dimensional structure with high porosity, and required size and shape of the pores. In this review, state of the art of the most common fabrication methods of three-dimensional biomimetic scaffolds are presented that include: solvent casting particle leaching (SCPL), thermally induced phase separation (TIPS), and liquid induced phase separation (LIPS)

Positron annihilation in bioactive glass/poly(glycolide-co-L-lactide) composites

Composites made of bioactive glasses and resorbable polymers are promising biomaterials for bone tissue regeneration. In this study several types of composites produced from bioactive glasses, differing in chemical composition (A2 and S2) and poly(glycolide-co-lactide) (PGLA) were obtained. The resulting composite materials were investigated with positron lifetime spectroscopy and Doppler broadening of annihilation line. It was found that for the composites made of S2 bioglass the intensity of the third positron lifetime component coming from the positronium (Ps) annihilation decreased with increasing in volume fraction of bioglass particles exhibiting behaviour characteristic of microcomposites. For the composites produced from A2 bioglass, such a dependence was not found. The differences obtained may be connected with chemical composition of the bioglass and/or its crystallinity

Bioactive glasses for tissue engineering

Ceramika jest materiałem implantacyjnym powszechnie stosowanym w ortopedii oraz stomatologii. W ostatnich latach szczególną uwagę zwrócono na wykorzystanie materiałów bioaktywnych, do których należą między innymi bioaktywne szkła i szkło-ceramika. W obszarze kontaktu mają one zdolność wywołania specyficznej odpowiedzi biologicznej, która prowadzi do tworzenia trwałego wiązania pomiędzy tkanką i materiałem. Bioaktywność szkieł w dużej mierze zależy od ich składu chemicznego, procesu wytwarzania (proces wysokotemperaturowy lub zol-żel) oraz obróbki termicznej. Uwalniane z powierzchni szkła jony mogą wpływać na odpowiedź wewnątrz- i zewnątrzkomórkową. Jednoczesne aktywowanie odpowiednich genów osteoblastów prowadzi do ich proliferacji oraz produkcji macierzy zewnątrzkomórkowej. W opracowaniu przedstawiono podział ceramiki ze względu na sposób oddziaływania z tkankami, opisano mechanizm bioaktywności szkieł w kontakcie z płynem fizjologicznym, a także możliwości badania tego zjawiska w warunkach in vitro. Ponadto, dokonano porównania właściwości bioaktywnych szkieł wytwarzanych tradycyjną metodą topienia oraz metodą zol-żel.Ceramic materials are widely used in a variety of orthopaedic and dental applications. Over the last few years considerable attention has been directed towards the use of bioactive materials i.e. bioactive glasses and glass-ceramics. They have the ability to elicit a specific biological response at the interface of the material, which results in the formation of a bond between the tissues and the material. Bioactivity of glass mainly depends on the chemical composition, manufacturing process (melt and sol-gel derived glasses) and thermal treatment. The ions released from the glass surface can induce extracellular and intracellular response. Simultaneous activation of the numerous genes leads to proliferation of osteoblasts and expression of extracellular matrix components. The classification of ceramic materials based on the type of material-tissue interaction, the mechanism of glass bioactivity in physiological media, and the possibility of investigation of this phenomenon were presented. Furthermore, the properties comparison of melt-derived glasses and sol-gel-derived glasses was carried out

Influence of environmental factors on contact lenses properties

Nowadays contact lenses are a very common way of vision correction. To be used successfully, they must meet a number of conditions. This article describes studies on the influence of environmental factors such as low temperature (4°C), high temperature (60°C), various fluids (simulated tear fluid (STF), physiological saline, multi-purpose contact lens solution) and ultraviolet radiation on the properties (wettability, dehydration, UV-vis transmission, surface structure/ microstructure) of 3rd generation silicone hydrogel contact lenses. Contact angle measurement device, gravimetric method (measurement of dehydration), UV-vis spectrophotometry, ATR spectroscopy and SEM microscopy were used during the research. The results showed that environmental factors can influence some features of comfilcon A contact lenses. The reduction of contact lens water content, being the result of a long-term storage at high temperature, might cause changes in their elasticity, thereby sense of discomfort for the user, while storage in physiological saline causes slight decrease in visible light transmission. What is more, the temperature and fluids used for storage of silicone hydrogel contact lenses, as well as ultraviolet radiation affect the microstructure of analysed lenses