Paul Slezak

Extracorporeal shock wave therapy (ESWT) is a well-known biophysical therapy that offers several beneficial effects, including a presumed increase in the growth of blood vessels. The chorioallantoic membrane (CAM) assay is a well-established in vivo model for studying angiogenesis. The aim of this study was to develop an experimental setup to apply ESWT to CAM in a three-step process and investigate the vascular response. First, we conducted virtual simulations of various shock-wave application setups to CAM and subsequently tested them in preliminary studies to evaluate their feasibility. In the final stage, we employed the most suitable protocol to investigate the angiogenic effects of shock wave therapy in practical applications. Our findings suggest that ESWT increases the number of vessels in CAM. In the final biological experiment (n = 16 CAM per group), ESWT increased vessel number by approximately 14.3% (p = 0.050) and branching points by approximately 13.5% (p = 0.070), while mean vessel thickness decreased by approximately 8.0% (p = 0.047); total vascular area per image remained unchanged (p = 0.760). These effects were concentrated in short-to-medium, thinner-caliber vessels rather than reflecting a uniform increase in vascularity, consistent with the emergence of a denser microvascular network. This new experimental setup paves the way for future research into the angiogenic effects of ESWT and provides a multifaceted model as an intermediate step between in vitro mechanistic studies and clinical translation.

Background: This study aimed to optimize low-intensity extracorporeal shockwave therapy (Li-ESWT) for the treatment of penile indications through the addition of a secondary reflector. The therapeutic potential of Li-ESWT is well-established, but its efficiency is limited by uncontrolled wave propagation and reflection resulting in regions of increased tensile pressures. The objective is to manage and reduce high tensile pressure and enhance treatment efficacy by reflecting applied shockwaves back into the treatment zone using a novel reflector design. Methods: A comprehensive investigation, including numerical modeling and phantom measurements, exploring a range of improvements to traditional shockwave application by reflecting applied therapeutic shockwaves back into the treatment zone. Computational optimization was employed to identify the most suitable secondary reflector shape for potential future clinical use. Subsequent hydrophone phantom reference measurements were extended to volumetric fields using 3D simulations. Results: Traditional treatment resulted in high tensile pressures in the treatment zone, which was mitigated by introducing an impedance-matched layer (IML) while preserving the initial shockwave’s therapeutic function. The addition of the secondary reflector enabled controlled refocusing of the therapeutic shockwave back into the initial focal zone, thus either increasing the treatment volume or achieving a rapid secondary application. Choice of the reflector’s impedance allowed for the secondary refocusing of either a tensile or positive pressure wave. Conclusions: The combined modifications of employing an IML and secondary reflector eliminate uncontrolled tensile waves and reflections, provide better control over consecutive reflections, and enable repeated shockwave signals with a single applicator shot, potentially reducing the number of required shots per session.

Environmental biophysical interactions are recognized to play an essential part in the human biological processes associated with trauma recovery. Many studies over several decades have furthered our understanding of the effects that Pulsed Electromagnetic Fields (PEMF) have on the human body, as well as on cellular and biophysical systems. These investigations have been driven by the observed positive clinical effects of this non-invasive treatment on patients, mainly in orthopedics. Unfortunately, the diversity of the various study setups, with regard to physical parameters, molecular and cellular response, and clinical outcomes, has made it difficult to interpret and evaluate commonalities, which could, in turn, lead to finding an underlying mechanistic understanding of this treatment modality. In this review, we give a birds-eye view of the vast landscape of studies that have been published on PEMF, presenting the reader with a scaffolded summary of relevant literature starting from categorical literature reviews down to individual studies for future research studies and clinical use. We also highlight discrepancies within the many diverse study setups to find common reporting parameters that can lead to a better universal understanding of PEMF effects.

Chronic wounds remain a serious clinical problem with insufficient therapeutic approaches. In this study we investigated the dose dependency of rhVEGF₁₆₅ in fibrin sealant in both ischemic and non-ischemic excision wounds using our recently developed impaired-wound healing model. An abdominal flap was harvested from the rat with unilateral ligation of the epigastric bundle and consequent unilateral flap ischemia. Two excisional wounds were set in the ischemic and non-ischemic area. Wounds were treated with three different rhVEGF₁₆₅ doses (10, 50 and 100 ng) mixed with fibrin or fibrin alone. Control animals received no therapy. Laser Doppler imaging (LDI) and immunohistochemistry were performed to verify ischemia and angiogenesis. Wound size was monitored with computed planimetric analysis. LDI revealed insufficient tissue perfusion in all groups. Planimetric analysis showed slower wound healing in the ischemic area in all groups. Wound healing was fastest with fibrin treatment—irrespective of tissue vitality. Lower dose VEGF (10 and 50 ng) led to faster wound healing compared to high-dose VEGF. Immunohistochemistry showed the highest vessel numbers in low-dose VEGF groups. In our previously established model, different rhVEGF₁₆₅ treatments led to dose-dependent differences in angiogenesis and wound healing, but the fastest wound closure was achieved with fibrin matrix alone.

Photobiomodulation, showing positive effects on wound healing processes, has been performed mainly with lasers in the red/infrared spectrum. Light of shorter wavelengths can significantly influence biological systems. This study aimed to evaluate and compare the therapeutic effects of pulsed LED light of different wavelengths on wound healing in a diabetic (db/db) mouse excision wound model. LED therapy by Repuls was applied at either 470 nm (blue), 540 nm (green) or 635 nm (red), at 40 mW/cm² each. Wound size and wound perfusion were assessed and correlated to wound temperature and light absorption in the tissue. Red and trend-wise green light positively stimulated wound healing, while blue light was ineffective. Light absorption was wavelength-dependent and was associated with significantly increased wound perfusion as measured by laser Doppler imaging. Shorter wavelengths ranging from green to blue significantly increased wound surface temperature, while red light, which penetrates deeper into tissue, led to a significant increase in core body temperature. In summary, wound treatment with pulsed red or green light resulted in improved wound healing in diabetic mice. Since impeded wound healing in diabetic patients poses an ever-increasing socio-economic problem, LED therapy may be an effective, easily applied and cost-efficient supportive treatment for diabetic wound therapy.

Dysbiosis and impaired gastrointestinal barrier function have emerged as potential chronic kidney disease (CKD) modulators. Accumulation of gut-derived uremic toxins, a subsequent shift in the gut microbiome, and modified expression levels of intestinal tight junction proteins are all contributing factors to hyperpermeability and endotoxemia in CKD. Experimental studies in animals provide evidence that renal decline is linked to gastrointestinal health and that pharmacological or dietary intervention might attenuate this process. In this review, we will highlight the current knowledge on CKD-induced changes in the gut microbiome and the resulting consequences regarding gastrointestinal health with a focus on animal studies. Furthermore, we will explore possible disease management options linking to evidence in humans, if available.

Background: Fibrin sealants are used as antimicrobial-releasing carriers for preventing surgical site infections; however, it is important to determine the release kinetics and antimicrobial effects of drugs added to fibrin sealants and the effects of drugs on clot/clotting properties. Materials and Methods: The antimicrobial and antibiofilm activity of cefazolin, colistin, gentamicin, oxacillin, tobramycin, and silver nitrate released from fibrin sealant were characterized using in vitro and ex vivo assays against bacteria commonly found on the skin. The effects of antimicrobial agents on the physical structure of the fibrin sealant were assessed with scanning electron microscopy (SEM) and on the clotting rate and strength of fibrin clots using run-off tests and rheology. Results: Generally, antibiotic agents were released gradually from fibrin sealant and were stable after release, with antimicrobial effects evident up to three days. Cefazolin, gentamicin, and oxacillin prevented biofilm formation of Staphylococcus aureus in porcine skin explants; gentamicin and colistin prevented biofilm formation of Pseudomonas aeruginosa . Gentamicin, cefazolin, colistin, and tobramycin did not affect the structural integrity or viscoelastic properties of fibrin sealant; changes were observed with oxacillin (SEM) and particularly silver nitrate (SEM and rheology). No antimicrobial agents caused deterioration of clotting time (run-off tests). Conclusions: From the antimicrobial agents tested, gentamicin and cefazolin showed prolonged release from fibrin sealant, sustained antimicrobial activity, and biofilm prevention properties against Staphylococcus aureus ; similar results were observed for gentamicin and colistin against Pseudomonas aeruginosa . For each of these findings, the physical structure of the fibrin sealant, clotting rate, and strength of fibrin clots were unaffected.

Fibrin sealants are well‐established components of the surgical toolbox, especially in procedures that harbor a high risk of perioperative bleeding. Their widespread use as hemostats, sealants or tissue‐adhesives in various surgical settings has shown that the choice of the appropriate sealant system affects the clinical outcome. While many studies have compared the hemostatic efficiency of fibrin sealants to that of other natural or synthetic sealants, there is still limited data on how subtle differences in fibrin sealant formulations relate to their biological performance. Here, we performed an in‐depth physicochemical and biological characterization of the two most commonly used fibrin sealants in the US and Europe: TISSEEL™ (“FS”) and VISTASEAL™/VERASEAL™ (“FS+Osm”). Our chemical analyses demonstrated differences between the two sealants, with lower fibrinogen concentrations and supraphysiological osmolality in the FS+Osm formulation. Rheological testing revealed FS clots have greater clot stiffness, which strongly correlated with network density. Ultrastructural analysis by scanning electron microscopy revealed differences between FS and FS+Osm fibrin networks, the latter characterized by a largely amorphous hydrogel structure in contrast to the physiological fibrillar network of FS. Cytocompatibility experiments with human fibroblasts seeded on FS and FS+Osm fibrin networks, or cultured in presence of sealant extracts, revealed that FS+Osm induced apoptosis, which was not observed with FS. Although differential sealant osmolality and amounts of fibrinogen, as well as the presence of Factor XIII or additives such as antifibrinolytics, may explain the mechanical and structural differences observed between the two fibrin sealants, none of these substances are known to cause apoptosis at the respective concentrations in the sealant formulation. We thus conclude that hyper osmolality in the FS+Osm formulation is the primary trigger of apoptosis—a mechanism that should be evaluated in more detail, as it may affect the cellular wound healing response in situ.

Angiogenesis is a highly regulated process. It promotes tissue regeneration and contributes to tumor growth. Existing therapeutic concepts interfere with different steps of angiogenesis. The quantification of the vasculature is of crucial importance for research on angiogenetic effects. The chorioallantoic membrane (CAM) assay is widely used in the study of angiogenesis. Ex ovo cultured chick embryos develop an easily accessible, highly vascularised membrane on the surface. Tumor xenografts can be incubated on this membrane enabling studies on cancer angiogenesis and other major hallmarks. However, there is no commonly accepted gold standard for the quantification of the vasculature of the CAM. We compared four widely used measurement techniques to identify the most appropriate one for the quantification of the vascular network of the CAM. The comparison of the different quantification methods suggested that the CAM assay application on the IKOSA platform is the most suitable image analysis application for the vasculature of the CAM. The new CAM application on the IKOSA platform turned out to be a reliable and feasible tool for practical use in angiogenesis research. This novel image analysis software enables a deeper exploration of various aspects of angiogenesis and might support future research on new anti-angiogenic strategies for cancer treatment.