Senescence-Associated ß-Galactosidase Detection in Pathology.

Activity of ß-galactosidase at pH 6 is a classic maker of senescence in cellular biology. Cellular senescence, a state of highly stable cell cycle arrest, is often compared to apoptosis as an intrinsic tumor suppression mechanism. It is also thought that SA-ß-gal is crucial in malignant cell transformation. High levels of senescence-associated ß-galactosidase (SA-ß-gal) can be found in cancer and benign lesions of various localizations making the enzyme a highly promising diagnostic marker for visualization of tumor margins and metastases. These findings facilitate the research of therapy induced senescence as a promising therapeutic strategy. In this review, we address the need to collect and analyze the bulk of clinical and biological data on SA-ß-gal mechanisms of action to support wider implementation of this enzyme in medical diagnostics. The review will be of interest to pathologists, biologists, and biotechnologists investigating cellular senescence for purposes of regenerative medicine and oncology.

Analysis of the vein wall destruction under endovenous laser ablation in an ex vivo model.

This work was aimed at elaborating an experimental ex vivo endovenous laser ablation (EVLA) model and evaluating the possibility of using differential scanning calorimetry (DSC) to determine the degree of collagen denaturation of the venous tissue and optimize the laser treatment settings. The control (non-varicose) and varicose vein specimens were subjected to chemical, thermal and morphological analyses. Varicose vein fragments were irradiated with 1.56-µm and 0.97-µm lasers in conditions closely similar to those of the clinical EVLA procedure. The laser treated specimens were subjected to thermal and histological analyses. A noticeable difference in chemical composition and structure was detected between the control and varicose veins. Glycosaminoglycan content increased significantly in varicose vein (P = .02), elastin content decreased insignificantly (P = .26) while collagen content showed a slight, but not significant, increase (P = .14). Varicose vein demonstrated regional variability in wall thickness, some decrease in the amount of smooth muscle cells, thinning and loosening of collagen fibers and fibrosis. The critical laser radiation power was demonstrated simultaneously to cause complete denaturation of collagen (as indicated by the DSC data) and coagulation necrosis of all the three venous wall layers, total homogenization of the tissue and obliteration of vasa vasorum (as indicated by the histological analysis data). Lower laser radiation powers fail to produce these effects. Critical laser power provides the desired result of the thermal effect on the vein ex vivo, namely, tissue necrosis and vasa vasorum destruction. The complete degradation of the collagen recorded by DSC could be a marker of the irreversible destruction of the vein wall in modeling of endoluminal thermal treatment.

Ex vivo and animal study of the blue diode laser, Tm fiber laser, and their combination for laparoscopic partial nephrectomy.

BACKGROUND AND OBJECTIVES: To evaluate the feasibility of using a novel blue diode laser (blue laser), a thulium fiber laser (Tm laser), and their combination as a directed-energy surgical tool in laparoscopic partial nephrectomy (LPN). STUDY DESIGN/MATERIALS AND METHODS: The blue laser emitting at 442 nm, the Tm laser emitting at 1,940 nm wavelengths, and the combination of them were tested. First, cutting and coagulative abilities of the lasers were characterized ex vivo on porcine kidney in air and CO2 . Histological staining was performed to assess the efficiency of ablation and coagulation. Next, experimental LPN was performed on a porcine model at zero ischemia. Upper and lower segments of both kidneys were resected. Total operation time and resection time were measured; bleeding and carbonization were evaluated. RESULTS: Ex vivo data show that laser-induced ablation and coagulation processes do not differ substantially between CO2 and air environments. Histological analysis of ex vivo incisions demonstrates that the blue laser produced deep ablation with relatively narrow coagulation zone, whereas Tm laser was less efficient in terms of ablation but possessed excellent coagulative properties. Experimental LPN revealed that the blue laser provided fast cutting with minimal carbonization, whereas Tm laser induced slow cutting with strong carbonization. The combination of the blue and Tm lasers provided the most promising results demonstrating the highest resection rate, almost carbonization free resection surface and clinically acceptable hemostasis enabling LPN without the need for vessel clamping. CONCLUSIONS: The blue laser can be efficiently utilized in LPN. Furthermore, the combination of the blue and Tm lasers into a single modality may be beneficial for further development of successful laser-assisted LPN. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.

Chemical cross-linking of xenopericardial biomeshes: A bottom-up study of structural and functional correlations.

Decellularized bovine pericardium (DBP)-based biomeshes are the gold standard in reconstructive surgery. In order to prolong their stability after the transplantation, various chemical cross-linking strategies are employed. However, structural and functional properties of the biomeshes differ in dependence on the cross-linker used. Here, we performed a bottom-up study of structural and functional alterations of DBP-based biomeshes following cross-linking with hexamethylene diisocyanate (HMDC), ethylene glycol diglycidyl ether (EGDE), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and genipin. The in vitro cytotoxicity tests supported their clinical applicability. Their structural differences (eg roughness, fibre thickness, pore morphology) were evaluated using the two-photon confocal laser scanning, atomic force, scanning electron and polarized light microscopies. HMDC and EDC samples appeared to be the roughest. Complex mechanical trials indicated the tendency to reduced Young's Modulus and mechanical anisotropy values of DBP upon cross-linking. The lowest mechanical anisotropy was found in EDC and genipin sample groups. In vitro collagenase susceptibility was the highest for EDC samples and the lowest for EGDE samples. The comparative analysis of the results allowed us to recognize the strengths and weaknesses of each cross-linker in relation to a particular clinical application.

From Aggregates to Porous Three-Dimensional Scaffolds through a Mechanochemical Approach to Design Photosensitive Chitosan Derivatives.

The crustacean processing industry produces large quantities of waste by-products (up to 70%). Such wastes could be used as raw materials for producing chitosan, a polysaccharide with a unique set of biochemical properties. However, the preparation methods and the long-term stability of chitosan-based products limit their application in biomedicine. In this study, different scale structures, such as aggregates, photo-crosslinked films, and 3D scaffolds based on mechanochemically-modified chitosan derivatives, were successfully formed. Dynamic light scattering revealed that aggregation of chitosan derivatives becomes more pronounced with an increase in the number of hydrophobic substituents. Although the results of the mechanical testing revealed that the plasticity of photo-crosslinked films was 5⁻8% higher than that for the initial chitosan films, their tensile strength remained unchanged. Different types of polymer scaffolds, such as flexible and porous ones, were developed by laser stereolithography. In vivo studies of the formed structures showed no dystrophic and necrobiotic changes, which proves their biocompatibility. Moreover, the wavelet analysis was used to show that the areas of chitosan film degradation were periodic. Comparing the results of the wavelet analysis and X-ray diffraction data, we have concluded that degradation occurs within less ordered amorphous regions in the polymer bulk.