Papers by Ivana Gadjanski
Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature
During mesenchymal development, the microenvironment gradually transitions from one that is rich ... more During mesenchymal development, the microenvironment gradually transitions from one that is rich in cell-cell interactions to one that is dominated by cell-extracellular-matrix (ECM) interactions. Because these cues cannot readily be decoupled in vitro or in vivo, how they converge to regulate mesenchymal stem cell (MSC) mechanosensing is not fully understood. Here, we show that a hyaluronic acid hydrogel system enables, across a physiological range of ECM stiffness, the independent co-presentation of the HAVDI adhesive motif from the EC1 domain of N-Cadherin and the RGD adhesive motif from fibronectin. Decoupled presentation of these cues revealed that HAVDI ligation (at constant RGD ligation) reduced the contractile state and thereby nuclear YAP/TAZ localization in MSCs, resulting in altered interpretation of ECM stiffness and subsequent changes in downstream cell proliferation and differentiation. Our findings reveal that, in an evolving developmental context, HAVDI/N-Cadherin interactions can alter stem cell perception of the stiffening extracellular microenvironment.
Sensors
Foodborne pathogenic bacteria present a crucial food safety issue. Conventional diagnostic method... more Foodborne pathogenic bacteria present a crucial food safety issue. Conventional diagnostic methods are time-consuming and can be only performed on previously produced food. The advancing field of point-of-need diagnostic devices integrating molecular methods, biosensors, microfluidics, and nanomaterials offers new avenues for swift, low-cost detection of pathogens with high sensitivity and specificity. These analyses and screening of food items can be performed during all phases of production. This review presents major developments achieved in recent years in point-of-need diagnostics in land-based sector and sheds light on current challenges in achieving wider acceptance of portable devices in the food industry. Particular emphasis is placed on methods for testing nucleic acids, protocols for portable nucleic acid extraction and amplification, as well as on the means for low-cost detection and read-out signal amplification.
Neurobiology of Disease, 2005
In habitually loaded tissues, dynamic loading can trigger ATP (ade-nosine-5ʹ-triphosphate) releas... more In habitually loaded tissues, dynamic loading can trigger ATP (ade-nosine-5ʹ-triphosphate) release to the extracellular environment, and result in calcium signaling via ATP binding to purine P2 receptors. 1 In the current study, the purinergic responses (ATP release) of two types of cells: bovine chondrocytes (bCHs) and human mesenchymal stem cells (hMSCs) that were encapsulated in agarose and subjected to dynamic loading were compared. Both cell types were cultured under chondrogenic conditions, and their responses to loading were evaluated by an ATP release assay in combination with a connexin (Cx)-sensitive fluorescent dye (lucifer yellow – LY) and a Cx-hemichannel blocker (flufenamic acid – FFA). In response to dynamic loading , the chondrogenic hMSCs released significantly higher amounts of ATP (5-fold) in comparison to the bCHs early in culture (day 2). The triggering of LY uptake in the bCHs and hMSCs by dynamic loading implies opening of the Cx-hemichannels. However, the number of LY-positive cells in the hMSC-constructs was 2.5-fold lower compared to the loaded bCH-constructs, suggesting utilization of additional mechanisms of ATP release. Cx-reactive sites were detected in both the bCHs and hMSCs-constructs. FFA application led to reduced ATP release in both the bCHs and hMSCs, which confirmed the involvement of connexin hemichannels, with more prominent effects in the bCHs than in the hMSCs, further implying the existence of additional mechanisms of ATP release in chondrogenic hMSCs. Taken together, these results indicate a stronger purinergic response to dynamic loading of the chondrogenic hMSCs than that of primary chondrocytes, by activation of connexin hemichannels and additional mechanisms of ATP release.
Objective: The aim of this study was to investigate the role of voltage-dependent calcium channel... more Objective: The aim of this study was to investigate the role of voltage-dependent calcium channels (VDCCs) in axon degen-eration during autoimmune optic neuritis. Methods: Calcium ion (Ca 2) influx into the optic nerve (ON) through VDCCs was investigated in a rat model of optic neuritis using manganese-enhanced magnetic resonance imaging and in vivo calcium imaging. After having identified the most relevant channel subtype (N-type VDCCs), we correlated immunohistochemistry of channel expression with ON histopathology. In the confirmatory part of this work, we performed a treatment study using-conotoxin GVIA, an N-type specific blocker. Results: We observed that pathological Ca 2 influx into ONs during optic neuritis is mediated via N-type VDCCs. By analyzing the expression of VDCCs in the inflamed ONs, we detected an upregulation of 1B , the pore-forming subunit of N-type VDCCs, in demyelinated axons. However, high expression levels were also found on macrophages/activated microglia, and lower levels were detected on astrocytes. The relevance of N-type VDCCs for inflammation-induced axonal degeneration and the severity of optic neuritis was corroborated by treatment with-conotoxin GVIA. This blocker led to decreased axon and myelin degeneration in the ONs together with a reduced number of macrophages/activated microglia. These protective effects were confirmed by analyzing the spinal cords of the same animals. Interpretation: We conclude that N-type VDCCs play an important role in inflammation-induced axon degeneration via two mechanisms: First, they directly mediate toxic Ca 2 influx into the axons; and second, they contribute to macrophage/microglia function, thereby promoting secondary axonal damage.
Neuritis of the optic nerve is one of the most frequent early symptoms of multiple sclerosis. The... more Neuritis of the optic nerve is one of the most frequent early symptoms of multiple sclerosis. There are only scarce data correlating magnetic resonance imaging (MRI) contrast alterations with the underlying pathology, that is inflammation, demyelination, and axonal damage. Here we studied optic neuritis in a rat model of experimental autoimmune encephalomyelitis by comparing in vivo MRI findings from multiple techniques (T1, T2, proton density, magnetization transfer) to histo-pathology. We further assessed a breakdown of the blood–brain barrier by using Gd-DTPA and indirectly estimated the intracellular accumulation of calcium as a consequence of axonal damage by using manganese-enhanced MRI. Hyperintensity on T2-weighted images and signal enhancement after Gd-DTPA were highly sensitive to lesions of the optic nerve but did not differentiate between mild, moderate, and severe damage. Signal reduction on T1-weighted images was less sensitive but correlated well with the severity of tissue damage. No significant changes in magnetization transfer ratio were observed. Manganese ions tended to accumulate in the central parts of the inflamed optic nerve. The resulting signal enhancement at 24 h after administration positively correlated with the severity of axonal loss. Thus, manganese might be an indicator of intracellular calcium accumulation that is known to be associated with axon damage. Although none of the methods alone distinguished between inflammation, demyelination, and reduced axon density, their specific capabilities should prove useful for future in vivo MRI studies of optic neuritis in both animal models and humans.
In multiple sclerosis (MS), post-mortem studies of human brain tissue as well as data from animal... more In multiple sclerosis (MS), post-mortem studies of human brain tissue as well as data from animal models have shown that apoptosis of neurons occurs to a significant extent during this disease. As neuro-degeneration in MS correlates with permanent neurological deficits in patients, understanding the mechanisms would be an important precondition for designing appropriate neuroprotective therapies. Myelin oligodendrocyte glycoprotein-induced experimental autoimmune ence-phalomyelitis often affects the optic nerve and leads to consecutive apoptosis of retinal ganglion cells (RGCs), the neurons that form its axons. In this study, we fused Bcl-X L to the protein transduction domain of the HIV-transactivator of transcription. Thereby, this anti-apoptotic member of the Bcl-2 family was delivered into RGCs of rats with electrophysiologically diagnosed optic neuritis. Transduction of Bcl-X L in our study led to significant rescue of RGCs indicating the relevance of this pathway for neuronal survival under autoimmune inflammatory conditions.
F1000 - Post-publication peer review of the biomedical literature, 2000
F1000 - Post-publication peer review of the biomedical literature, 2000
F1000 - Post-publication peer review of the biomedical literature, 2000
F1000 - Post-publication peer review of the biomedical literature, 2000
F1000 - Post-publication peer review of the biomedical literature, 2000
F1000 - Post-publication peer review of the biomedical literature, 2000
2015 IEEE 15th International Conference on Bioinformatics and Bioengineering (BIBE), 2015
One of the key challenges in osteochondral tissue engineering is to achieve mechanical properties... more One of the key challenges in osteochondral tissue engineering is to achieve mechanical properties in the engineered tissue that are equivalent to the native tissue. Detailed knowledge of the mechanotransduction pathways occuring in the native tissue is necessary before manipulation towards the aimed properties in the engineered tissue. Purinergic (ATP-mediated) signaling is proving to be one of the main mechanisms how the chondrogenic cells sense and respond to the mechanical stimulation. In this study we performed experiments to evaluate the mechanosensitive purinergic response of chondrocytes and chondrogenic mesenchymal stem cells and we further developed a mathematical model showing ATP release changes in loaded vs. unloaded cell constructs over time. Such model can be of value in determining the potential for pharmacological manipulation of the purinergic mechanotransduction in the engineered osteochondral tissues.
2015 IEEE 15th International Conference on Bioinformatics and Bioengineering (BIBE), 2015
Expert Opinion on Biological Therapy, 2015
A major hurdle in treating osteochondral (OC) defects is the different healing abilities of two t... more A major hurdle in treating osteochondral (OC) defects is the different healing abilities of two types of tissues involved - articular cartilage and subchondral bone. Biomimetic approaches to OC-construct engineering, based on recapitulation of biological principles of tissue development and regeneration, have potential for providing new treatments and advancing fundamental studies of OC tissue repair. Areas covered: This review on state of the art in hierarchical OC tissue graft engineering is focused on tissue engineering approaches designed to recapitulate the native milieu of cartilage and bone development. These biomimetic systems are discussed with relevance to bioreactor cultivation of clinically sized, anatomically shaped human cartilage/bone constructs with physiologic stratification and mechanical properties. The utility of engineered OC tissue constructs is evaluated for their use as grafts in regenerative medicine, and as high-fidelity models in biological research. Expert opinion: A major challenge in engineering OC tissues is to generate a functionally integrated stratified cartilage-bone structure starting from one single population of mesenchymal cells, while incorporating perfusable vasculature into the bone, and in bone-cartilage interface. To this end, new generations of advanced scaffolds and bioreactors, implementation of mechanical loading regimens and harnessing of inflammatory responses of the host will likely drive the further progress.
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Papers by Ivana Gadjanski