Zbynek Tonar

Charles University in Prague | CUNI · Institute of Histology and Embryology (Pilsen)

Only a fraction of specimens under study are usually selected for quantification in histology. Multilevel sampling or tissue probes, slides and fields of view (FOVs) in the regions of interest (ROIs) are required. In general, all parts of the organs under study should be given the same probability to be taken into account; that is, the sampling sho...

Diabetic foot ulcer (DFU) is a serious complication of diabetes and hyperbaric oxygen therapy (HBOT) is also considered in comprehensive treatment. The evidence supporting the use of HBOT in DFU treatment is controversial. The aim of this work was to introduce a DFU model in ZDF rat by creating a wound on the back of an animal and to investigate th...

Despite the wide choice of commercial heart valve prostheses, cryopreserved semilunar allograft heart valves (C-AHV) are required, and successfully transplanted in selected groups of patients. The expiration limit (EL) criteria have not been defined yet. Most Tissue Establishments (TE) use the EL of 5 years. From physiological, functional, and surg...

The aim of the study was to develop an orthopedic implant coating in the form of vancomycin-loaded collagen/hydroxyapatite layers (COLHA+V) that combine the ability to prevent bone infection with the ability to promote enhanced osseointegration. The ability to prevent bone infection was investigated employing a rat model that simulated the clinical...

In liver surgery, biliary obstruction can lead to secondary biliary cirrhosis, a life-threatening disease with liver transplantation as the only curative treatment option. Mesenchymal stromal cells (MSC) have been shown to improve liver function in both acute and chronic liver disease models. This study evaluated the effect of allogenic MSC transpl...

Background/aim: Anastomotic leakage is a feared complication in colorectal surgery. Postoperative peritoneal adhesions can also cause life-threatening conditions. Nanofibrous materials showed their pro-healing properties in various studies. The aim of the study was to evaluate the impact of double-layered nanofibrous materials on anastomotic heali...

Objective: The liver is frequently injured in blunt abdominal trauma caused by road traffic accidents. The testing of safety performance of vehicles, e.g. belt usage, head support, seat shape, or air bag shape, material, pressure and reaction, could lead to reduction of the injury seriousness. Current trends in safety testing include development o...

Tumor oxygenation and vascularization are important parameters that determine the aggressiveness of the tumor and its resistance to cancer therapies. We introduce dual-modality ultrasound and photoacoustic imaging (US-PAI) for the direct, non-invasive real-time in vivo evaluation of oxygenation and vascularization of patient-derived xenografts (PDX...

Background: In patients with colorectal liver metastases, the possibility for radical liver resection can be limited by oxaliplatin-induced sinusoidal obstruction syndrome (SOS). This study investigates the potential of mesenchymal stem cells (MSC) to improve the outcome of liver resections in pigs with SOS. Materials and methods: SOS was induce...

The rise and growth of mechanistic thought and explanation has been a central theme in the historiography of biology in the twentieth and twenty first centuries. However, this historiography often treats mechanism and mechanistic thought as a distinct and distinguishable element within biology, one which was more or less uniform, and which possesse...

Hydrogels are suitable for osteochondral defect regeneration as they mimic the viscoelastic environment of cartilage. However, their biomechanical properties are not sufficient to withstand high mechanical forces. Therefore, we have prepared electrospun poly-ε-caprolactone-chitosan (PCL-chit) and poly(ethylene oxide)-chitosan (PEO-chit) nanofibers,...

Comment on: PETER MAKOVICKÝ, PAVOL MAKOVICKÝ: Histological aspects of skeletal muscle fibers splitting of C57BL/6NCrl mice.

Currently, there are at least 70 pure domestic pig breeds, but only certain breeds are used in biomedical research. The domestic pig liver is suitable for preclinical research because its size, physiology, and anatomy are similar to that of the human liver; in addition, there is a high degree of genetic similarity between the two species. For plann...

Anastomotic leakage is a severe complication in gastrointestinal surgery. It is often a reason for reoperation together with intestinal passage blockage due to formation of peritoneal adhesions. Different materials as local prevention of these complications have been studied, none of which are nowadays routinely used in clinical practice. Nanofabri...

Both acute and chronic liver diseases are frequent and potentially lethal conditions. Development of new therapeutic strategies and drugs depends on understanding of liver injury pathogenesis and progression, which can be studied on suitable animal models. Due to the complexity of liver injury, the understanding of underlying mechanisms of liver di...

Background: In clinical medicine, little is known about the use of allografts for portal vein (PV) reconstruction after pancreaticoduodenectomy (PD). Portal and caval systems are physiologically different, therefore the properties of allografts from caval and portal systems were studied here in a pig model. Materials and methods: PD with PV reco...

Information about the tissue characteristics of abdominal aortic aneurysms (AAAs), some of which may be reflected in the serum, can help to elucidate AAA pathogenesis and identify new AAA biomarkers. This information would be beneficial not only for diagnostics and follow-up but also for potential therapeutic intervention. Therefore, the aim of our...

Background: Using animal models in experimental medicine requires mapping of their anatomical variability. Porcine common carotid arteries (CCA) are often preferred for the preclinical testing of vascular grafts due to their anatomical and physiological similarity to human small-diameter arteries. Comparing the microscopic structure of animal mode...

Objective: The mechanical properties and microstructure of the perineal body are important for the improvement of numerical models of pelvic organs. We determined the mechanical parameters and volume fractions of the ewe perineal body as an animal model. Methods: The 39 specimens of 13 pregnant swifter ewes delivering by cesarean section (aged 2...

One of the main aims of bone tissue engineering, regenerative medicine and cell therapy is development of an optimal artificial environment (scaffold) that can trigger a favorable response within the host tissue, it is well colonized by resident cells of organism and ideally, it can be in vitro pre-colonized by cells of interest to intensify the pr...

Aim: This study evaluates the effect of electrospun dressings in critical sized full-thickness skin defects in rabbits. Materials & methods: Electrospun poly-ε-caprolactone (PCL) and polyvinyl alcohol (PVA) nanofibers were tested in vitro and in vivo. Results: The PCL scaffold supported the proliferation of mesenchymal stem cells, fibroblasts and k...

The aortic and pulmonary allograft heart valves (AHV) are used in the cardiac surgery for replacing the impaired semilunar valves. They are harvested from donor hearts and cryostored in tissue banks. The expiration period was set to 5 years arbitrarily. We hypothesized that their mechanical and structural properties do not deteriorate after this pe...

Laser capture microdissection (LCM) is an excellent tool using a laser beam for specific selection and harvesting of cells or cell populations from heterogeneous tissue sections prepared on special slides. The aim of our study was to apply mathematical methods for optimizing the planning of laser trajectory in LCM combining positive and negative se...

Lipid droplets are found in most cells, where they are needed for lipid metabolism and energy homeostasis. Their biogenesis is still not entirely described process, in which an organelle with monomolecular layer on the surface originates from two-layer membrane of the smooth endoplasmic reticulum. Large lipid droplets can be formed either by growth...

Background In glioblastoma, a fraction of malignant cells consists of therapy-resistant glioblastoma stem cells (GSCs) residing in protective niches that recapitulate hematopoietic stem cell (HSC) niches in bone marrow. We have previously shown that HSC niche proteins stromal cell-derived factor-1 α (SDF-1α), C-X-C chemokine receptor type 4 (CXCR4)...

This study evaluated the subacute morphologic alterations in renal artery wall and renal nerves in response to catheter-based renal denervation in sheep and also compared the efficiency of single-point and multiple-point ablation catheters. Effect of each ablation catheter approved for the clinical use (Symplicity Flex(TM), Medtronic, INC. or Enlig...

The study involved the electrospinning of the copolymer poly(L-lactide-co-ε-caprolactone) (PLCL) into tubular grafts. The subsequent material characterization, including micro-CT analysis, revealed a level of porosity of around 70%, with pore sizes of 9.34 ± 0.19 µm and fiber diameters of 5.58 ± 0.10 µm. Unlike fibrous polycaprolactone, the electro...

The aim of this study was to compare data on the volume fraction of bone and the thickness of the cortical compact bone acquired during microcomputed tomography (micro-CT) analysis with data acquired from identical samples using stereological analysis of either decalcified paraffin sections or ground sections. Additionally, we aimed to compare adja...

The pig is a large animal model that is often used in experimental medicine. The aim of this study was to assess, in normal pig livers, sexual dimorphism in the normal fraction of hepatic interlobular and intralobular connective tissue (CT) in six hepatic lobes and in three macroscopical regions of interest (ROIs) with different positions relative...

Objective: The perineal body connects muscles from the pelvic floor and is critical for support of the lower part of the vagina and proper function of the anal canal. We determined mechanical parameters and volume fractions of main components of the human female postmenopausal perineal body. Methods: The specimens were taken from 15 fresh female...

Aims: To evaluate the regional collagen fiber network in the human temporomandibular joint (TMJ) disc by using biochemical magnetic resonance imaging (MRI) and quantitative histology. Methods: MRI of 5 heads (10 TMJ discs) obtained from partially dentate or edentulous cadavers was performed at 3-Tesla MRI by using a flexible, 8-channel transmit-...

Bone regeneration is a long-term process requiring proper scaffolding and drug delivery systems. The current study delivers a three-dimensional (3D) scaffold prepared by blend centrifugal spinning loaded with the osteogenic supplements (OS) β-glycerol phosphate, ascorbate-2-phosphate and dexamethasone. The OS were successfully encapsulated into a f...

Bisphenols belong to the endocrine disruptors, affecting reproduction even in extremely low doses. Bisphenol S (BPS) has become widely used as a substitute for the earlier-used BPA; however, its harmnessless is questionable. The aim of this study was to evaluate the effect of BPS on folliculogenesis and oocyte quality after in vivo exposure to low...

Purpose Incisional hernia repair is an unsuccessful field of surgery, with long-term recurrence rates reaching up to 50% regardless of technique or mesh material used. Various implants and their positioning within the abdominal wall pose numerous long-term complications that are difficult to treat due to their permanent nature and the chronic forei...

Aims: Micro-CT is a powerful and well-established method for non-destructive visualization and analysis in 2D and 3D. However, the verification of results obtained by micro-CT analysis of structural characteristics at micro-scale level is complicated and hard to achieve. Bias introduced by image noise, image processing (e.g. noise-reducing operatio...

Introduction: Sinusoidal obstruction syndrome (SOS) is a disease which is caused by toxic injury to hepatic sinusoids. This syndrome is most frequently caused by myeloablative radiochemotherapy in patients before hematopoietic stem cells transplantation and also by oxaliplatin mainly in patients with colorectal liver metastases. The aim of this st...

Introduction: Portal vein embolization or ligation (PVE/PVL) is part of most multi-stage liver procedures in the case of low future liver remnant volume (FLRV). PVE initiates compensatory hypertrophy of non-occluded liver parenchyma. This hypertrophy is stimulated by an increased volume of portal blood in the non-occluded veins. PVE results in ade...

Micro-CT (micro-computed tomography) is a modern preclinical imaging method allowing non-destructive visualizations and structure analysis yielding at a resolution of a few micrometres. Tissue engineering scaffolds are a promising treatment for bone defects. Micro-CT application for the evaluation of tissue engineering scaffolds for bone surgery an...

Quantification of the structure and composition of biomaterials using micro-CT requires image segmentation due to the low contrast and overlapping radioopacity of biological materials. The amount of bias introduced by segmentation procedures is generally unknown. We aim to develop software that generates three-dimensional models of fibrous and poro...

Introduction Glioblastoma multiforme (GBM) represents the most malignant primary brain tumor characterized by pathological vascularization. Mutations in isocitrate dehydrogenases 1 and 2 (IDH1 and IDH2) were observed in GBM. We aimed to assess the intra-tumor hypoxia, angiogenesis and microvessel formation in GBM and to find their associations with...

In glioblastoma, a fraction of malignant cells consists of therapy-resistant glioblastoma stem cells (GSCs) residing in protective niches that recapitulate hematopoietic stem cell (HSC) niches in bone marrow. We have previously shown that HSC niche proteins stromal cell-derived factor-1α (SDF-1α), C-X-C chemokine receptor type 4 (CXCR4), osteoponti...

Currently, titanium endosseous implants represent the standard in dental implantology. To improve their mechanical properties, biocompatibility and osseointegration, the concept of bulk nanostructured titanium with variously textured surface is being developed. Different animal species, mostly pigs, minipigs and rabbits, are used for the osseointeg...

Lipid droplets are found in most cells, where they are needed for lipid metabolism and energy homeostasis. Their biogenesis is still not entirely described process, in which an organelle with mono-molecular layer on the surface originates from two-layer membrane of the smooth endoplasmic reticulum. Large lipid droplets can be formed either by growt...

To provide basic data on the local differences in density of microvessels between various parts of the human brain, including representative grey and white matter structures of the cerebral hemispheres, the brain stem and the cerebellum, we quantified the numerical density NV and the length density LV of microvessels in two human brains. We aimed t...

Fibrous scaffolds are desired in tissue engineering applications for their ability to mimic extracellular matrix. In this study we compared fibrous scaffolds prepared from polycaprolactone using three different fabrication methods, electrospinning, electro-blowing and melt-blown combined with electrospinning. Scaffolds differed in morphology, fiber...

Porcine liver is widely used as a model organ in experimental surgery. The ammount of connective tissue (CT) is key histological parameter for analysis of such experiments, but no quantitative study of the CT displacement in the porcine liver has been published so far, nor a valid sampling scheme. Therefore, we: 1. Quantified area fraction of the C...

Lentiviruses are suitable to transfer potential therapeutic genes into non-replicating cells such as neurons, but systematic in vivo studies on transduction of neural cells within the complete brain are missing. We analysed the distribution of transduced cells with respect to brain structure, virus tropism, numbers of transduced neurons per brain,...

In teaching and learning human anatomy, anatomical autopsy and prosected specimens have always been indispensable. However, alternative methods must often be used to demonstrate particularly delicate structures. Corrosion casting of porcine organs with Biodur E20® Plus is valuable for teaching and learning both gross anatomy and, uniquely, the micr...

Renal sympathetic hyperactivity is critically involved in hypertension pathophysiology; renal denervation (RDN) presents a novel strategy for treatment of resistant hypertension cases. This study assessed effects of two RDN systems to detect acute intravascular, vascular and peri-vascular changes in the renal artery, and renal nerve alterations, in...

“If you can't explain it simply, you don't understand it well enough”. This paraphrase of Albert Einstein's thought is as valid as ever. We are living in an age of rapid increase of information, which places escalating demands on students who are under the pressure of incredible progresses in biomedical sciences. It is thus vitally important from t...

s The primary objective was to create a clinically relevant model of right ventricular hypertension and to study right ventricular myocardial pathophysiology in growing organism. The secondary objective was to analyse the effect of oral enoximone (phosphodiesterase inhibitor) therapy on right ventricular haemodynamic parameters and myocardial chang...

Human cryopreserved allografts of pulmonary and aortic valves are routinely used as total valve replacement. For successful surgery it is needed to sufficiently preserve biomechanical properties and histological structures of allografts. However, it is not known how the mechanical properties of these allografts relate to their histological composit...

We analyzed histological data statistically describing the distribution of orientations of vascular smooth muscle cells (VSMC) within porcine aorta. The data were correlated with the fractions of actin, desmin, vimentin, elastin and collagen within the same samples. In samples with more contractile VSMC and less elastin, the symmetrical helices of...

The porcine liver is frequently used as a large animal model for verification of surgical techniques, as well as experimental therapies. Often, a histological evaluation is required that include measurements of the size, nuclearity or density of hepatocytes. Our aims were to assess the mean number-weighted volume of hepatocytes, the numerical densi...

The aim of this paper is to review the experimental methods currently being used to evaluate the osseointegration of nanostructured titanium implants using animal models. The material modifications are linked to the biocompatibility of various types of oral implants, such as lasertreated, acid-etched, plasma-coated, and sand-blasted surface modific...

Tunica adventitia or tunica externa is the outer layer of the blood vessel wall. It consists of connective tissue with vasa and nervi vasorum and plays a key role in vascular health. The aim of our study was to compare the wall layers beyond tunica media in arteries of different type and location. The following arteries of pig, dog and cat were pro...

Introduction: The descending branch of the lateral circumflex femoral artery (DBLCFA) has been suggested as an option for use in coronary artery bypass grafting (CABG). Our aim was to combine radiological examination, surgical and anatomical preparation, and histological assessment of the DBLCFA to map its variability and to assess the benefits of...

Degenerative affections of nerve tissues are often accompanied by changes of vascularization. In this regard, not much is known about hereditary cerebellar degeneration. In this study, we compared the vascularity of the individual cerebellar components and the mesencephalon of three-month-old wild type mice (n=5) and Lurcher mutant mice, which repr...

The primary data of the stereological assessment of cerebellar vascularity in the wild type (WT) and Lurcher (Lc) mice.

Statistical evaluation of reported values when comparing wild type and Lurcher mice. (A) Mann–Whitney U-test to compare both animal groups; (B) Wilcoxon signed-rank test for comparing the data within each group.

Purpose: Quantitative description of hepatic microvascular bed could contribute to understanding perfusion CT imaging. Micro-CT is a useful method for the visualization and quantification of capillary-passable vascular corrosion casts. Our aim was to develop and validate open-source software for the statistical description of the vascular networks...

A number of growth and differentiation factors are involved in tissue healing to restore cells, tissue matrix, and microvascular bed. These processes may be targeted and promoted by in vivo implantation of bioengineered meshes and fibers. This chapter reviews the chemical composition, dimensions, surface modifications, and spatial properties (spaci...