Halim Ayan

Exogenous nitric oxide (NO) generated by NO-plasma treatment modulates osteoprogenitor cells early differentiation

In this study, we investigated whether nitric oxide (NO) generated using a non-thermal plasma system can mediate osteoblastic differentiation of osteoprogenitor cells without creating toxicity. Our objective was to create an NO delivery mechanism using NO-dielectric barrier discharge (DBD) plasma that can generate and transport NO with controlled concentration to the area of interest to regulate osteoprogenitor cell activity. We built a non-thermal atmospheric pressure DBD plasma nozzle system based on our previously published design and similar designs in the literature. The electrical and spectral analyses demonstrated that N2 dissociated into NO under typical DBD voltage–current characteristics. We treated osteoprogenitor cells (MC3T3-E1) using NO-plasma treatment system. Our results demonstrated that we could control NO concentration within cell culture media and could introduce NO into the intracellular space using NO-plasma treatment with various treatment times. We confirmed that NO-plasma treatment maintained cell viability and did not create any toxicity even with prolonged treatment durations. Finally, we demonstrated that NO-plasma treatment induced early osteogenic differentiation in the absence of pro-osteogenic growth factors/proteins. These findings suggest that through the NO-plasma treatment system we are able to generate and transport tissue-specific amounts of NO to an area of interest to mediate osteoprogenitor cell activity without subsequent toxicity. This opens up the possibility to develop DBD plasma-assisted tissue-specific NO delivery strategies for therapeutic intervention in the prevention and treatment of bone diseases.

Equiaxial Strain Modulates Adipose-derived Stem Cell Differentiation within 3D Biphasic Scaffolds towards Annulus Fibrosus

Recurrence of intervertebral disc (IVD) herniation is the most important factor leading to chronic low back pain and subsequent disability after discectomy. Efficacious annulus fibrosus (AF) repair strategy that delivers cells and biologics to IVD injury site is needed to limit the progression of disc degeneration and promote disc self-regeneration capacities after discectomy procedures. In this study, a biphasic mechanically-conditioned scaffold encapsulated with human adipose-derived stem cells (ASCs) is studied as a potential treatment strategy for AF defects. Equiaxial strains and frequencies were applied to ASCs-encapsulated scaffolds to identify the optimal loading modality to induce AF differentiation. Equiaxial loading resulted in 2–4 folds increase in secretion of extracellular matrix proteins and the reorganization of the matrix fibers and elongations of the cells along the load direction. Further, the equiaxial load induced region-specific differentiation of ASCs within the inner and outer regions of the biphasic scaffolds. Gene expression of AF markers was upregulated with 5–30 folds within the equiaxially loaded biphasic scaffolds compared to unstrained samples. The results suggest that there is a specific value of equiaxial strain favorable to differentiate ASCs towards AF lineage and that ASCs-embedded biphasic scaffold can potentially be utilized to repair the AF defects.

Miniature Dielectric Barrier Discharge Nonthermal Plasma Induces Apoptosis in Lung Cancer Cells and Inhibits Cell Migration

Traditional cancer treatments like radiotherapy and chemotherapy have drawbacks and are not selective for killing only cancer cells. Nonthermal atmospheric pressure plasmas with dielectric barrier discharge (DBD) can be applied to living cells and tissues and have emerged as novel tools for localized cancer therapy. The purpose of this study was to investigate the different effects caused by miniature DBD (mDBD) plasma to A549 lung cancer cells. In this study, A549 lung cancer cells cultured in 12 well plates were treated with mDBD plasma for specified treatment times to assess the changes in the size of the area of cell detachment, the viability of attached or detached cells, and cell migration. Furthermore, we investigated an innovative mDBD plasma-based therapy for localized treatment of lung cancer cells through apoptotic induction. Our results indicate that plasma treatment for 120 sec causes apoptotic cell death in 35.8% of cells, while mDBD plasma treatment for 60 sec, 30 sec, or 15 sec causes apoptotic cell death in 20.5%, 14.1%, and 6.3% of the cell population, respectively. Additionally, we observed reduced A549 cell migration in response to mDBD plasma treatment. Thus, mDBD plasma system can be a viable platform for localized lung cancer therapy.

Sterilization of Biofilm on a Titanium Surface Using a Combination of Nonthermal Plasma and Chlorhexidine Digluconate

Nosocomial infections caused by opportunistic bacteria pose major healthcare problem worldwide. Out of the many microorganisms responsible for such infections, Pseudomonas aeruginosa is a ubiquitous bacterium that accounts for 10–20% of hospital-acquired infections. These infections have mortality rates ranging from 18 to 60% and the cost of treatment ranges from

Localized surface functionalization of polycaprolactone with atmospheric-pressure microplasma jet

20,000 to

Antimicrobial Effectiveness of Regular Dielectric-Barrier Discharge (DBD) and Jet DBD on the Viability of Pseudomonas aeruginosa

80,000 per infection. The formation of biofilms on medical devices and implants is responsible for the majority of those infections. Only limited progress has been made to prevent this issue in a safe and cost-effective manner. To address this, we propose employing jet plasma to break down and inactivate biofilms in vitro. Moreover, to improve the antimicrobial effect on the biofilm, a treatment method using a combination of jet plasma and a biocide known as chlorhexidine (CHX) digluconate was investigated. We found that complete sterilization of P. aeruginosa biofilms can be achieved after combinatorial treatment using plasma and CHX. A decrease in biofilm viability was also observed using confocal laser scanning electron microscopy (CLSM). This treatment method sterilized biofilm-contaminated surfaces in a short treatment time, indicating it to be a potential tool for the removal of biofilms present on medical devices and implants.

Sterilization of methicillin-resistant staphylococcus aureus with dielectric barrier discharge

Surface properties of biopolymers are crucial for providing topographical and chemical cues to affect cellular behaviors, such as attachment, spreading, viability, proliferation, and differentiation. As an effective surface modification technique, plasma treatment is often applied to enhance surface wettability, adhesion, and biocompatibility of polymers. In this study, an atmospheric-pressure microplasma jet based on dielectric barrier discharge was installed on an automated arm which allows movement in the x–y–z directions at various trajectory presets. Polycaprolactone (PCL) samples were functionalized with helium-oxygen plasma generated by this system and characterized via water contact angle, x-ray photoelectron spectroscopy, and scanning electron microscopy. Mouse osteoblast cells (7F2) were cultured on both treated and native PCL samples and examined by MarkerGene™ Live: Dead/Cytotoxicity and alamarBlue® assaying techniques. The surface and biological characterization results indicate that microplasma treatment improved surface hydrophilicity, as well as cell viability and proliferation. The localized microplasma treatment can lead to the application of bioactive scaffolds with selective surface functionalization.

Investigation of non-thermal plasma effects on lung cancer cells within 3D collagen matrices

Bacterial biofilm formation on medical implants is a major cause of illness in patients and is, therefore, increasing healthcare costs due to extended hospital stays and the failure/disposal of contaminated implants. Only limited progress has been made to prevent or eradicate this growing problem. Effective approaches include inhibiting the initiation of biofilm growth by killing planktonic bacteria and breaking down existing biofilms. We propose to employ atmospheric pressure nonthermal regular dielectric-barrier discharge (DBD) and jet plasma to kill bacteria that have been grown planktonically or in biofilms. In this paper, Pseudomonas aeruginosa was grown either planktonically or on titanium coupons in a bioreactor under dynamic conditions to form mature biofilms. The planktonic bacteria and biofilms were exposed to regular DBD and jet plasma and bacterial survival was evaluated after treatment for various times and at different distances. Within 5 min of plasma treatment, we observed complete decontamination of planktonically grown bacteria, and within 15 min, we observed more than a 3 log reduction (99.9%) of bacteria grown as biofilms. The efficacy of plasma treatment was also visualized using scanning electron microscopy, where disruption of biofilm was found with an increasing treatment time. This paper also determined that jet plasma is more effective in treating biofilms than regular DBD plasma.

Antimicrobial Effectiveness of Regular Dielectric- Barrier Discharge (DBD) and Jet DBD on the Viability of Pseudomonas aeruginosa

In this study we aim to address treatment of Staphylococcus aureus, one of the most common causes of infection after injury or surgery. Besides the infecting wounds, Staphylococcus aureus may even spread to the bone and antibiotic resistance in Staphylococcus aureus is a serious problem. The application of atmospheric pressure non-thermal dielectric barrier discharge is an effective method in decontamination of the living tissue. In this project we apply non-thermal plasma on contaminated liquid and surfaces to evaluate sterilization efficacy with log reduction in bacterial concentration as a function of different parameters such as plasma treatment time and power density. We test the effects of non-thermal plasma treatment in decontamination of Staphylococcus aureus, methicillinresistant Staphylococcus aureus and Escherichia coli (as benchmark species) in different media and on different surfaces. Mechanisms of plasma decontaminations were studied using various assays and characterization methods. All three bacteria species were studied in their early logarithmic growth phase and late lag phase. In conclusion, we found that atmospheric pressure non-thermal plasma can effectively sterilize methicillin-resistant Staphylococcus aureus.