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Abstract:
The growing popularity of solution blow spinning as a method for the production of fibrous tissue engineering scaffolds and the vast range of polymer-solvent systems available for the method raises the need to study the effect of processing conditions on fiber morphology and develop a method for its qualitative assessment. Rheological approaches to determine polymer solution spinnability and image analysis approaches to describe fiber diameter and alignment have been previously proposed, although in a separate manner and mostly for the widely known, well-researched electrospinning method. In this study, a series of methods is presented to determine the processing conditions for the development of submicron fibrous scaffolds. Rheological methods are completed with extensive image analysis to determine the spinnability window for a polymer–solvent system and qualitatively establish the influence of polymer solution concentration and collector rotational speed on fiber morphology, diameter, and alignment. Process parameter selection for a tissue engineering scaffold target application is discussed, considering the varying structural properties of the native extracellular matrix of the tissue of interest.

Keywords:
solution blow spinning, rheology, image analysis, nanofibers, fiber alignment, biodegradable nanofibers

Abstract:
Background: Currently, radiotherapy is one of the most popular choices in clinical practice for the treatment of cancers. While it offers a fantastic means to selectively kill cancer cells, it can come with a host of side effects. To minimize such side effects, and maximize the therapeutic effect of the treatment, we propose the use of targeted radiopharmaceuticals. In the study presented herein, we investigate two synthetic pathways of dextran-based radiocarriers and provide their key chemical and physical properties: stability of the bonding of chelating agent and tertiary structure of obtained formulations and its influence on biological properties. Additionally, PSMA small molecule inhibitor was attached and quantified using DELFIA fluorescence assay. Finally, biological properties and radiolabeling yield were studied using confocal microscopy and ITLC-SG chromatography. Results: Two types of Dex-conjugates - micelle-like nanoparticles (NPs) and non-folded conjugates - were successfully generated and shown to exhibit cellular effects. The tertiary structure of the conjugates was found to influence the selectivity of PSMA and mediate cell binding as well as cellular uptake mechanisms. NPs were shown to be internalized by other, non - PSMA mediated channels. Simultaneously, the uptake of non-folded conjugates required PSMA inhibitor to pass through cell membrane. The radiochemical yield of NHS coupled DOTA chelator was between 91.3 and 97.7% while the TCT-amine bonding showed higher stability and gave the yields of 99.8-100%. Conclusions: We obtained novel, dextran-based radioconjugates, and presented a superior method of chelator binding, resulting in exquisite radiochemical properties as well as selective cross-membrane transport.

Keywords:
dextran, radioconjugates, nanoparticles, prostate cancer, DOTA-conjugates

Abstract:
When evaluating a novel bone substitute material, advanced in vivo testing is an important step in development and safety affirmation. Sheep seems to be a valuable model for human one turnover and remodeling activity. The experimental material composed with the stem cells is an advanced therapy medicinal product (acc. to EC Regulation 1394/2007). Our research focuses on histological differences in bone formation (guided bone regeneration n GBR) in sheep maxillas after implantation of the new chitosan / tricalcium phosphate / alginate (CH/TCP/Alg) biomaterial in comparison to the commercially available xenogenic bone graft and a/m enhanced with the stem cells isolated from the adipose tissue. Twelve adult female sheep of BCP synthetic line, weighing 60-70 kg were used for the study. The 11 mm diameter defects in maxilla bone were prepared with a trephine bur under general anesthesia and then filled with the bone substitute materials: CH/TCP/Alg, BioOss Collagen, Geistlich AG (BO), CH/TCP/Alg composed with the stem cells (CH/S) or left just with the blood clot (BC). Inbreeding cycle of the animals terminated at 4 months after surgery. Dissected specimens of the maxilla were evaluated histologically and preliminary under microtomography. Histological evaluation showed early new bone formation observed around the experimental biomaterial and commercially available BO. There were no features of purulent inflammation and necrosis, or granulomatous inflammation. Microscopic examination after 4 months following the surgery revealed trabecular bone formation around chitosan based bone graft and xenogenic material with no significant inflammatory response. Different results – no bone recreation were observed for the negative control (BC). In conclusion, the tested materials (CH/TCP/Alg and BO) showed a high degree of biocompatibility and some osteoconductivity in comparison with the control group. Although the handiness, granules size and setting time of CH/TCP/Alg may be refined for future clinical tests. The relevant beneficial influence of using the adipose derived stem cells in GBR was not confirmed in this model.

Keywords:
alginate, bone substitute material, chitosan, guided bone regeneration, β-tricalcium phosphate, sheep model, stem cells

Abstract:
In the hereby presented work the authors describe a technique of high-compression-resistant biodegradable bone scaffold preparation. The methodology is based on the agglomeration of chitosan (CH) and chitosan/β-tricalcium phosphate (CH/TCP) microspheres and represents a novel approach to 3D matrices design for bone tissue engineering application. The materials were prepared from high deacetylation degree chitosan. The authors describe the method for scaffold fabrication, essential properties of the materials manufactured and the influence of various TCP concentrations on material morphology, mechanical properties (for dry and hydrated materials) and preliminary study on the interaction between CH or CH/TCP scaffolds and within cultured MG-63 osteoblast-like cells. The properties of the obtained materials were significantly affected by the calcium phosphate content, which had a particular influence on the granule microstructure, size distribution and inner biomaterial pore size. The water uptake ability was found to be lower for the materials enriched with the inorganic phase and tended to decrease with the increasing calcium phosphate concentration. The evaluation of mechanical properties has revealed that scaffolds produced with the usage of granule-based technology display a potential to be used as a load-bearing material since the Young’s modulus values were limited to the range of 200–500 MPa for dry materials and 15–20 MPa for the hydrated state of the scaffolds. The cell number, identified in three time points (48 h, 7 and 14 days) by Pico Green assay, was lower for the materials enriched with inorganic phase (75 % of control), however cell distribution, when compared to CH only biomaterial, was acknowledged as steadier on the surface of the material containing the highest calcium phosphate concentration.

Abstract:
Over the last few years, alloplastic bone substitute materials are raising much interest as an alternative to autologic transplants and xenogenic materials especially in oral surgery. These non-immunogenic and completely resorbable biomaterials are becoming the basis for complete and predictable guided bone regeneration in many cases. The objective of our research was to evaluate the dynamics of bone formation in rats’ skulls after implantation of the new chitosan/tricalcium phosphate/alginate biomaterial in comparison to the commercially available alloplastic bone graft. A total of 45 adult male rats weighing 300–400 g were used for the study. The 85-mm-diameter defects in calvaria bone were prepared with a trephine bur, and then filled with the bone substitute materials: chitosan/tricalcium phosphate/alginate or easy-graft Classic (Degradable Solutions AG) (EA) or left just with the blood clot. Animals were sacrificed at 1 and 3 months for histological, histomorphometrical and micro-tomographic evaluations. Histological evaluation at 1 month showed early new bone formation, observed around the experimental biomaterial (CH/TCP/Alg). There were no features of purulent inflammation and necrosis or granulomatous inflammation. Microscopic examination after 3 months following the surgery revealed trabecular bone formation around chitosan-based bone graft with no significant inflammatory response. Less satisfactory and differing results were observed for the commercially available EA and control blood clot. The tested material (chitosan) showed a high degree of biocompatibility and osteoconductivity in comparison with the control groups. Additionally, it seemed to be a “user-friendly” material for oral surgeons.

Keywords:
Alginate, bone substitute material, chitosan, guided bone regeneration, β-tricalcium phosphate, rat model