No abstract

Effective skeletal muscle tissue engineering relies on control over the scaffold architecture for providing muscle cells with the required directionality, together with a mechanical property match with the surrounding tissue. Although recent advances in 3D printing fulfill the first requirement, the available synthetic polymers either are too rigid or show unfavorable surface and degradation profiles for the latter. In addition, natural polymers that are generally used as hydrogels lack the required mechanical stability to withstand the forces exerted during muscle contraction. Therefore, one of the most important challenges in the 3D printing of soft and elastic tissues such as skeletal muscle is the limitation of the availability of elastic, durable, and biodegradable biomaterials. Herein, we have synthesized novel, biocompatible and biodegradable, elastomeric, segmented polyurethane and polyurethaneurea (TPU) copolymers which are amenable for 3D printing and show high elasticity, low modulus, controlled biodegradability, and improved wettability, compared to conventional polycaprolactone (PCL) and PCL-based TPUs. The degradation profile of the 3D printed TPU scaffold was in line with the potential tissue integration and scaffold replacement process. Even though TPU attracts macrophages in 2D configuration, its 3D printed form showed limited activated macrophage adhesion and induced muscle-like structure formation by C2C12 mouse myoblasts in vitro, while resulting in a significant increase in muscle regeneration in vivo in a tibialis anterior defect in a rat model. Effective muscle regeneration was confirmed with immunohistochemical assessment as well as evaluation of electrical activity produced by regenerated muscle by EMG analysis and its force generation via a custom-made force transducer. Micro-CT evaluation also revealed production of more muscle-like structures in the case of implantation of cell-laden 3D printed scaffolds. These results demonstrate that matching the tissue properties for a given application via use of tailor-made polymers can substantially contribute to the regenerative outcomes of 3D printed tissue engineering scaffolds.

Background: Bortezomib, an inhibitor of 26S proteasome, is an anti-cancer therapeutic agent used in different cancer types. It leads to the arrest of the cancerous cell cycle by inhibiting angiogenesis and inducing apoptosis. Liver is the vital organ for detoxification and excretion of toxic products. The treatment with chemotherapy is a challenge, drugs are used to destroy cancer cells, but healthy cells can be affected during cancer treatment as well. The main objective of this study was to analyze the histopathological and biochemical effects of bortezomib on liver.Materials, Methods & Results: Twenty-four female C57BL/6 mice were distributed into 4 groups, bortezomib injected treatment groups (Btz1, Btz2) and saline injected control groups (C1, C2). Bortezomib and saline treated twice per week for 6 weeks and sacrificed at the end of one day (Btz1, C1) and 4 weeks (Btz2, C2) after the last injection. Liver samples were examined for histopathological analysis and the serum samples processed for biochemical analysis. Tissue samples were fixed, routinely processed, sectioned, and stained with Hematoxylin and Eosin (H&E). Periodic Acid-Schiff (PAS), Sudan Black staining and Masson's trichrome histochemical staining methods were performed to characterize the lesions. Histopathological analysis of the Btz1 and Btz2 groups revealed acute hepatic morphological changes such as hepatocellular swelling (cloudy swelling), necro-inflammatory reaction, and increased mononuclear polyploidy. Based on the negative staining with PAS and Sudan Black staining, hepatocellular swelling was diagnosed as hydropic degeneration. Necro-inflammatory reaction observed in the form of acute hepatitis was composed of mainly mononuclear cell infiltration accompanied by multifocal necrotic foci. Kupffer cell proliferation was observed in parallel with degenerative and necrotic changes. An Increase in hepatocellular mononuclear polyploidy visualized as hepatocytes with a single enlarged nucleus was detected in all liver sections of Btz1 and Btz2 groups Individual cases of cholestasis (n = 1) and mild hepatic fibrosis (n = 1) were also reported. Significant elevated levels of alanine aminotransferase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP) and gamma-glutamyl transferase (GGT) were detected in bortezomib treated groups.Discussion: Few clinical casesreported liver injury related to bortezomib used for cancer treatment. However, the liver was not considered as a target for bortezomib treatment. Our data suggesting that bortezomib caused liver damage and induce elevations in serum levels. The reported hepatic lesions including hepatocellular swelling, acute hepatitis and mononuclear polyploidy were mainly mild and moderate in severity. The increase of polyploidy in liver tissue of mice treated with bortezomib in this study was explained as a reaction of the liver facing the drug-induced hepatic damage. The mechanism leading to the hepatotoxicity of bortezomib treatment is not known but the production of a toxic metabolite through its metabolism in the liver can be suggested. Moreover, no recovery was also observed in histopathological and biochemical analyses suggesting that the bortezomib effect is non-reversible four weeks after the drug was withdrawn. Patients should be informed about the possibility of acute drug-induced hepatitis and hepatotoxicity of this chemotherapeutic agent after the treatment.Keywords: bortezomib, cancer, chemotherapy, hepatotoxicity, liver, proteasome inhibitor.

Pilomatricoma is a benign adnexal skin neoplasm uncommonly reported in dogs. Three nodules surgically removed from the back of a 13-year-old female papillon dog at the Surgery Department of Ankara University, Faculty of Veterinary Medicine, formed the material of this study. The mass formation started six months earlier. Surgically resected nodules were sent to the Pathology Department of Ankara University, Faculty of Veterinary Medicine, for a detailed histopathological examination. Grossly, the nodules were 1x0,5x0,5 cm; 2x2x1 cm and 1x1x1 cm in diameter and covered with ulcerated skin. The masses were elastic in consistency with yellow-reddish cut sections. Histopathological examination revealed subcutaneous cystic structures surrounded by ghost cells or shadow cells and containing keratin filaments on the surface in all the nodules. The tumor was diagnosed according to the pilomatricoma chronological staging method used in human medicine as an early stage of pilomatricoma due to the presence of cystic structures and the absence of calcification and giant cells. This study is thought to assist by the definition of early lesion of canine pilomatricoma to the histopathological classification of pilomatricomas in canine species.

No abstract