Aysegül Temiz Artmann

Osmotic fragility (OF) is widely used to evaluate red blood cell (RBC) membrane stability, water transport dynamics and hemoglobinopathies, traditionally via spectrophotometric, visual, or flow cytometric techniques. Here, we present a novel flow chamber-based platform integrated with a proprietary imaging software providing AI-driven RBC detection for automated and reproducible OF analysis (BioExP). To assess agreement, we compared MCF₅₀ values from four healthy donors using classical and flow chamber methods. Protocol optimization included determining the “satiation time” (optimal incubation required to induce maximal hemolysis without overexposure) and hemolysis kinetics. Biological sensitivity was tested using two modulators: HgCl₂ (40 µM) to inhibit aquaporin (AQP) channels and lipopolysaccharide (LPS, 1000 µg/mL) to increase membrane fragility. Both treatments caused significant shifts in MCF₅₀ when compared to control: AQP inhibition decreased MCF₅₀ to 0.37 ± 0.01% NaCl (flow chamber) and 0.40 ± 0.01% NaCl (classical), while LPS increased MCF₅₀ to 0.44 ± 0.01% NaCl and 0.47 ± 0.004% NaCl, respectively ( p < 0.001 for all). The BioExP replicated classical OF measurements, captured donor-specific variability, and detected changes. Importantly, it demonstrated that LPS alone, in plasma-free conditions, can compromise RBC membrane integrity. The platform requires minimal sample volume and enables real-time imaging and multi-condition testing.

We propose the interfacial water quantum-transition (IWQ) model to explain how proteins respond to temperature changes through specific quantum transitions of water at the protein-water interface. This model links key functional temperatures, such as human body temperature, to these transitions. By examining proteins like hemoglobin and thermosensitive channels, the IWQ model reveals a fundamental connection between water behavior and biological temperature regulation, shedding light on evolutionary adaptations in humans and animals.

We propose the Interfacial Water Quantum-transition model (IWQ model) explaining temperature-dependent functional transitions in proteins. The model postulates that measured critical temperatures, T_C, correspond to reference temperatures, T_W, defined by rotational quantum transitions of temporarily free water molecules at the protein-water interface. The model’s applicability is demonstrated through transitions in hemoglobin and thermosensitive TRP channels. We suggest this mechanism also defines basal body temperatures in homeotherms, with T_W=36.32°C for humans. We demonstrate that human (mammal) and chicken (Aves) body temperatures align with specific reference temperatures, and correlate with pronounced transitions at T_C in hemoglobin oxygen saturation. This suggests evolutionary adaptations in homeotherms involve an interplay between oxygen supply and water’s rotational transition temperatures. The IWQ-model states that proteins sense and water sets critical physiological temperatures. Significance Statement We propose the Interfacial Water Quantum-transition (IWQ) model that offers a new way to understand how proteins respond to critical temperature changes. We suggest that the key temperatures at which proteins change their function are linked to specific quantum transitions of water molecules at the protein-water interface. This model explains why certain critical temperatures, like human body temperature, align with these transitions. By exploring this connection in proteins like hemoglobin and in thermosensitive channels, the IWQ model highlights a fundamental link between water behavior and biological temperature regulation, shedding light on evolutionary adaptations in humans and other animals.

Advances in polymer science have significantly increased polymer applications in life sciences. We report the use of free-standing, ultra-thin polydimethylsiloxane (PDMS) membranes, called CellDrum, as cell culture substrates for an in vitro wound model. Dermal fibroblast monolayers from 28- and 88-year-old donors were cultured on CellDrums. By using stainless steel balls, circular cell-free areas were created in the cell layer (wounding). Sinusoidal strain of 1 Hz, 5% strain, was applied to membranes for 30 min in 4 sessions. The gap circumference and closure rate of un-stretched samples (controls) and stretched samples were monitored over 4 days to investigate the effects of donor age and mechanical strain on wound closure. A significant decrease in gap circumference and an increase in gap closure rate were observed in trained samples from younger donors and control samples from older donors. In contrast, a significant decrease in gap closure rate and an increase in wound circumference were observed in the trained samples from older donors. Through these results, we propose the model of a cell monolayer on stretchable CellDrums as a practical tool for wound healing research. The combination of biomechanical cell loading in conjunction with analyses such as gene/protein expression seems promising beyond the scope published here.

Biocompatibility, flexibility and durability make polydimethylsiloxane (PDMS) membranes top candidates in biomedical applications. CellDrum technology uses large area, p < 0.01). They also differed from the calculated values. At room temperatures between 22 and 26 °C, significant differences in average thickness values were found, as well as a continuous decrease in thicknesses within a 4 °C temperature elevation. No correlation was found between the membrane thickness groups (between 3–4 µm) in terms of deflection and compliance. We successfully present a fabrication method for thin bio-functionalized membranes in conjunction with a four-step quality management system. The results highlight the importance of tight regulation of production parameters through quality control. The use of membranes described here could also become the basis for material testing on thin, viscous layers such as polymers, dyes and adhesives, which goes far beyond biological applications.

Background: Septic cardiomyopathy increases mortality by 70% to 90% and results in mechanical dysfunction of cells. Methods: Here, we created a LPS-induced in-vitro sepsis model with mouse embryonic stem cell-derived cardiomyocytes (mESC-CM) using the CellDrum technology which simultaneously measures mechanical compliance and beat frequency of mESCs. Visualization of reactive oxygen species (ROS), actin stress fibers, and mRNA quantification of endothelial protein C receptor (EPCR) and protease-activated receptor 1 (PAR1) before/after LPS incubation were used for method validation. Since activated protein C (APC) has cardioprotective effects, samples were treated with human recombinant APC (rhAPC) with/-out LPS predamage to demonstrate the application in therapeutic studies. Results: Twelve hours LPS treatment (5 μg/mL) increased ROS and decreased actin stress fiber density and significantly downregulated EPCR and PAR1 compared to control samples (0.26, 0.39-fold respectively). rhAPC application (5 μg/mL, 12 h) decreased ROS and recovered actin density, EPCR, and PAR1 levels were significantly upregulated compared to LPS predamaged samples (4.79, 3.49-fold respectively). The beat frequencies were significantly decreased after 6- (86%) and 12 h (73%) of LPS application. Mechanical compliance of monolayers significantly increased in a time-dependent manner, up to eight times upon 12-h LPS incubation compared to controls. rhAPC incubation increased the beat frequency by 127% (6h-LPS) and 123% (12h-LPS) and decreased mechanical compliance by 68% (12h-LPS) compared to LPS predamaged samples. Conclusion: LPS-induced contraction dysfunction and the reversal effects of rhAPC were successfully assessed by the mechanical properties of mESC-CMs. The CellDrum technology proved a decent tool to simulate sepsis in-vitro.

This study aimed to establish a precise and well-defined working model, assessing pharmaceutical effects on vascular smooth muscle cell monolayer in-vitro. It describes various analysis techniques to determine the most suitable to measure the biomechanical impact of vasoactive agents by using CellDrum technology. The so-called CellDrum technology was applied to analyse the biomechanical properties of confluent human aorta muscle cells (haSMC) in monolayer. The cell generated tensions deviations in the range of a few N/m² are evaluated by the CellDrum technology. This study focuses on the dilative and contractive effects of L-type Ca2+ channel agonists and antagonists, respectively. We analyzed the effects of Bay K8644, nifedipine and verapamil. Three different measurement modes were developed and applied to determine the most appropriate analysis technique for the study purpose. These three operation modes are called, particular time mode" (PTM), "long term mode" (LTM) and "real-time mode" (RTM). It was possible to quantify the biomechanical response of haSMCs to the addition of vasoactive agents using CellDrum technology. Due to the supplementation of 100nM Bay K8644, the tension increased approximately 10.6% from initial tension maximum, whereas, the treatment with nifedipine and verapamil caused a significant decrease in cellular tension: 10nM nifedipine decreased the biomechanical stress around 6,5% and 50nM verapamil by 2,8%, compared to the initial tension maximum. Additionally, all tested measurement modes provide similar results while focusing on different analysis parameters. The CellDrum technology allows highly sensitive biomechanical stress measurements of cultured haSMC monolayers. The mechanical stress responses evoked by the application of vasoactive calcium channel modulators were quantified functionally (N/m²). All tested operation modes resulted in equal findings, whereas each mode features operation-related data analysis.

To restore damaged organ function or to investigate organ mechanisms, it is necessary to prepare replicates that follow the biological role model as faithfully as possible. The interdisciplinary field of tissue engineering has great potential in regenerative medicine and might overcome negative side effects in the replacement of damaged organs. In particular, tubular organ structures of the genitourinary tract, such as the ureter and urethra, are challenging because of their complexity and special milieu that gives rise to incrustation, inflammation and stricture formation. Tubular biohybrids were prepared from primary porcine smooth muscle cells embedded in a fibrin gel with a stabilising poly(vinylidene fluoride) mesh. A mechanotransduction was performed automatically with a balloon kyphoplasty catheter. Diffusion of urea and creatinine, as well as the bursting pressure, were measured. Light and electron microscopy were used to visualise cellular distribution and orientation. Histological evaluation revealed a uniform cellular distribution in the fibrin gel. Mechanical stimulation with a stretch of 20% leads to a circumferential orientation of smooth muscle cells inside the matrix and a longitudinal alignment on the outer surface of the tubular structure. Urea and creatinine permeability and bursting pressure showed a non-statistically significant trend towards stimulated tissue constructs. In this proof of concept study, an innovative technique of intraluminal pressure for mechanical stimulation of tubular biohybrids prepared from autologous cells and a composite material induce bi-directional orientation of smooth muscle cells by locally and cyclically applied mechanical tension. Such geometrically driven patterns of cell growth within a scaffold may represent a key stage in the future tissue engineering of implantable ureter replacements that will allow the active transportation of urine from the renal pelvis into the bladder.