In Vitro Synergistic Photodynamic, Photothermal, Chemodynamic, and Starvation Therapy Performance of Chlorin e6 Immobilized, Polydopamine-Coated Hollow, Porous Ceria-Based, Hypoxia-Tolerant Nanozymes Carrying a Cascade System.

A synergistic therapy agent (STA) with photothermal, photodynamic, chemodynamic, and starvation therapy (PTT, PDT, CDT, and ST) functions was developed. Hollow, mesoporous, and nearly uniform CeO2 nanoparticles (H-CeO2 NPs) were synthesized using a staged shape templating sol-gel protocol. Chlorin e6 (Ce6) was adsorbed onto H-CeO2 NPs, and a thin polydopamine (PDA) layer was formed on Ce6-adsorbed H-CeO2 NPs. Glucose oxidase (GOx) was bound onto PDA-coated Ce6-adsorbed H-CeO2 NPs to obtain the targeted STA (H-CeO2@Ce6@PDA@GOx NPs). A reversible photothermal conversion behavior with the temperature elevations up to 34 °C was observed by NIR laser irradiation at 808 nm. A cascade enzyme system based on immobilized GOx and intrinsic catalase-like activity of H-CeO2 NPs was rendered on STA for enhancing the effectiveness of PDT by elevation of ROS generation and alleviation of hypoxia in a tumor microenvironment. Glucose-mediated generation of highly toxic hydroxyl radicals (·OH) was evaluated for CDT. The effectiveness of PDT on glioblastoma T98G cells was markedly enhanced by O2 generation started by the decomposition of glucose. A similar increase in cell death was also observed when ST and CDT functions were enhanced by photothermal action. The viability of T98G cells decreased to 10.6% by in vitro synergistic action including ST, CDT, PDT, and PTT without using any antitumor agent.

Investigation of UV-treated mesenchymal stem cells in an in vitro wound model.

This study examines the effects of ultraviolet-induced adipose tissue-derived mesenchymal stem cells and their supernatants on wound healing regarding cell viability, percentage of wound healing, released cytokine, and growth factors. It has been reported in previous studies that mesenchymal stem cells are resistant to ultraviolet light and have a protective effect on skin cells against ultraviolet-induced damage. At the same time, there are many studies in the literature about the positive effects of cytokines and growth factors secreted by mesenchymal stem cells. Based on this information, the effects of ultraviolet-induced adipose-derived stem cells and supernatants containing their secreted cytokines and growth factors on an in vitro two-dimensional wound model created with two different cell lines were investigated in this study. It was determined from the results that the highest cell viability and the least apoptotic staining were 100 mJ in mesenchymal stem cells (**p < 0.01). Furthermore, analysis of cytokines and growth factors collected from supernatants also supported 100 mJ as the optimal ultraviolet dose. It was observed that cells treated with ultraviolet and their supernatants significantly increased cell viability and wound-healing rate over time compared to other groups. In conclusion, with this study, it has been shown that adipose-derived stem cells exposed to ultraviolet light can have an important use in wound healing, both with their potential and with the more cytokines and growth factors they secrete. However, further analysis and animal experiments should be performed before clinical use.

Effects of calcium silicate cements on neuronal conductivity.

Objectives: This study evaluated alterations in neuronal conductivity related to calcium silicate cements (CSCs) by investigating compound action potentials (cAPs) in rat sciatic nerves. Materials and Methods: Sciatic nerves were placed in a Tyrode bath and cAPs were recorded before, during, and after the application of test materials for 60-minute control, application, and recovery measurements, respectively. Freshly prepared ProRoot MTA, MTA Angelus, Biodentine, Endosequence RRM-Putty, BioAggregate, and RetroMTA were directly applied onto the nerves. Biopac LabPro version 3.7 was used to record and analyze cAPs. The data were statistically analyzed. Results: None of the CSCs totally blocked cAPs. RetroMTA, Biodentine, and MTA Angelus caused no significant alteration in cAPs (p > 0.05). Significantly lower cAPs were observed in recovery measurements for BioAggregate than in the control condition (p < 0.05). ProRoot MTA significantly but transiently reduced cAPs in the application period compared to the control period (p < 0.05). Endosequence RRM-Putty significantly reduced cAPs. Conclusions: Various CSCs may alter cAPs to some extent, but none of the CSCs irreversibly blocked them. The usage of fast-setting CSCs during apexification or regeneration of immature teeth seems safer than slow-setting CSCs due to their more favorable neuronal effects.

Comparison of the different isoforms of vitamin e against amyloid beta-induced neurodegeneration.

Neurodegeneration is the progressive loss of structure or function of neurons. Amyloid beta oligomers and aggregates have been linked to neurodegeneration. While previous studies have suggested that dietary α-tocopherol intake can prevent amyloid beta aggregation and protect the brain against neurotoxicity, other research, however, indicated that tocotrienol forms might be used as an alternate agent against this kind of degeneration. In the presented research, we compared the in vitro protective effects of α-tocopherol and α-tocotrienol. In this context, we formed an in vitro neurodegeneration model with primary isolated neurons and measured α-tocopherol's and α-tocotrienol's protective effects. As a result, α-tocopherol and α-tocotrienol prevent the degeneration of neurons. Moreover, α-tocopherol and α-tocotrienol regulated the neuron's calcium channels mechanism by decreasing the expression of the calcium channel alpha 1C subunit. We also observed that the amount of amyloid beta accumulation in the extracellular matrix decreased with the application of these isoforms. In specific time points, α-tocopherol and α-tocotrienol differ in terms of protective effects. In conclusion, it could be interpreted that, in more extended periods, α-tocotrienol could be a significant protective agent against amyloid beta-induced neurodegeneration, and it can be used as an alternative to other protective agents, especially α-tocopherol.

DMSA-coated cubic iron oxide nanoparticles as potential therapeutic agents.

Aim: Superparamagnetic cubic iron oxide nanoparticles (IONPs) were synthesized and functionalized with meso-2,3-dimercaptosuccinic acid (DMSA) as a potential agent for cancer treatment. Methods: Monodisperse cubic IONPs with a high value of saturation magnetization were synthesized by thermal decomposition method and functionalized with DMSA via ligand exchange reaction, and their cytotoxic effects on HeLa cells were investigated. Results: DMSA functionalized cubic IONPs with an edge length of 24.5 ± 1.9 nm had a specific absorption rate value of 197.4 W/gFe (15.95 kA/m and 488 kHz) and showed slight cytotoxicity on HeLa cells when incubated with 3.3 × 1010, 6.6 × 1010 and 9.9 × 1010 NP/mL for 24, 48 and 72 h. Conclusion: To the best of our knowledge, this is the first study to investigate both the cytotoxic effects of DMSA-coated cubic IONPs on HeLa cells and hyperthermia performance of these nanoparticles.

Comparative Effects of Single-Dose Cardioplegic Solutions Especially in Repeated Doses During Minimally Invasive Aortic Valve Surgery.

OBJECTIVE: This study aims to compare del Nido cardioplegia (DNC) and histidine-tryptophan-ketoglutarate (HTK) cardioplegic solutions in minimally invasive aortic valve replacement (mini-AVR) surgery to discuss the safety level of myocardial protection and rationale for redosing intervals. METHODS: During the period from January 2017 to June 2019, 200 patients undergoing mini-AVR (solely or with concomitant procedures) were prospectively randomized to DNC (n = 100) andHTK (n = 100), both up to 90 minutes ischemic time. Patients with ischemic time over 90 minutes, needing a redosing, were further analyzed in 2 subgroups with DNC-R (n = 30) and HTK-R (n = 36). Sensitive biomarkers, in addition to routine biochemistry, were also documented at baseline (T1), after cessation of cardiopulmonary bypass (T2), and on the first postoperative day (T3). Transmural myocardial biopsies were sampled for staining. RESULTS: No statistical differences could be demonstrated in DNC and HTK groups with up to 90 minutes cross-clamp times in routine biochemical measurements and basic perioperative clinical outcomes. DNC-R showed significantly more arrhythmia/AV block incidence resulting in more extended intensive care unit (ICU) stay. Interleukin-6 and syndecan-1 in DNC and DNC-R groups were substantially higher at T2. Aquaporin-4 levels were significantly lower in the DNC-R group, demonstrating unsatisfactory response of cells to an excessive volume at T2. CONCLUSIONS: DNC and HTK provided acceptable myocardial protection as single-dose applications. DNC-R had significantly unbalanced levels of biomarkers, and more arrhythmia/AV block incidence resulting in more extended ICU stay. For patients who may need redosing HTK may be preferable to DNC.

Long-Term Protective Effects of Single-Dose Cardioplegic Solutions in Cell Culture Models.

Despite the popularity of single-dose cardioplegic techniques, the time window and targeted population for successful reperfusion remain unclear. We tested currently available techniques based on cell viability and integrity to demonstrate long-term cardioprotection and clarify whether these solutions were performed on neonatal/adult endothelium and myocardium by examining different cell lines. Cell viability with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test proliferation assay and membrane integrity with the lactic dehydrogenase (LDH) cytotoxicity test were documented in a cell culture/microscopy setting on adult (human umbilical vein endothelium [HUVEC]), neonatal (H9C2-cardiomyocytes), and myofibroblast (L929) cell lines. Apoptotic cell activity and necrosis were evaluated by acridine orange/propidium iodide (AO/PI) staining. Twenty-four hours after seeding, cells were incubated in control (Dulbecco's modified Eagle), St. Thomas and blood cardioplegia (4:1), histidine-tryptophan-ketoglutarate (HTK), and del Nido solutions at 32°C followed by an additional 6, 24, and 48 hours in standard conditions (37°C, 5% CO2). Experiments were repeated eight times. In MTT cell viability analysis, HTK protection was significantly better than the control medium in L929 cell lines at 48th hours follow-up and acted markedly better on the HUVEC cell line at 24th and 48th hours. del Nido and HTK provided significantly better protection on H9C2 (at 24th and 48th hours). Apoptotic and necrotic cell scoring as a result of AO/PI staining was found consistent with MTT results. The LDH test demonstrated that the level of cell disruption was significantly higher for St. Thomas and blood cardioplegia in H9c2 cells. Experimental studies on cardioplegia aimed at assessing myocardial protection use time-consuming and often expensive approaches that are unrealistic in clinical practice. We have focused on identifying the most effective cell types and the direct consequences of different cardioplegia solutions to document long-term effects that we believe are the most underestimated ones in the cardioplegia literature.

Effects of N-acetyl cysteine, vitamin E and vitamin C on liver glutathione levels following amiodarone treatment in rats.

INTRODUCTION: Amiodarone, a pharmaceutical extensively used to suppress atrial and ventricular tachyarrhythmias, is also known to cause many side effects on many tissues. N-acetyl-cysteine (NAC), vitamin E and vitamin C are known as antioxidants for their ability to minimize oxidative stress. In the peer-reviewed literature, there is no study reporting on the protective effects of these antioxidant agents against its hepatotoxicity. AIM: We investigated the oxidative effects of NAC, vitamins E and C on liver tissue after amiodarone treatment. MATERIAL AND METHODS: Rats were randomly assigned to: control; amiodarone group; amiodarone + NAC treated group; amiodarone + Vit. E group and amiodarone + Vit. C group. Liver tissues were isolated from animals and total glutathione levels were measured. RESULTS: In all time intervals, the level of glutathione increased. When all time intervals were compared, the amiodarone group revealed the lowest levels. The antioxidant co-administered group was studied; the glutathione levels were statistically significantly higher than the sole amiodarone group. When vitamins E, C or N-acetyl cysteine were examined, there was no statistically significant difference among them. CONCLUSIONS: In this study we found that hepatotoxicity capacity of amiodarone may be reduced by taking up antioxidants. In addition, the effect documented here may be reproducible and may be applied to clinical settings.

The cytotoxic properties and apoptotic potential of N-butyl and 2-octyl cyanoacrylates used in surgical treatment of chronic venous insufficiency.

BACKGROUND: This study aims to investigate the cytotoxic effects and apoptotic potential of N-butyl cyanoacrylate and 2-octyl cyanoacrylate used in surgical treatment of chronic venous insufficiency. METHODS: N-butyl cyanoacrylate and 2-octyl cyanoacrylate were cultured in cell-culture using human umbilical endothelial cell-line. Cytotoxicity and viability were assessed at 24 and 72 hours with lactate dehydrogenase and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays, respectively. Apoptotic potential was documented at 24 and 72 hours with relative caspase-3 activity. RESULTS: The mean cytotoxicity at 24 and 72 hours were: N-butyl cyanoacrylate with an area of dot/line: 37.0±3.9%/29.3±2.7% and 46.4±1.6%/45.1±7.1%, 2-octyl cyanoacrylate with an area of dot/line: 39.0±7.0%/37.3±4.6% and 47.0±2.3%/40.7±7.5%. Cytotoxicity increased by time in each group (p<0.05). The mean viability at 24 and 72 hours were: N-butyl cyanoacrylate with an area of dot/line: 53.4±7.7%/72.0±5.7% and 35.7±1.9%/37.8±3.7%, 2-octyl cyanoacrylate with an area of dot/line: 54.3±4.4%/73.5±19.9% and 33.6±2.8%/30.7±4.5%. The mean viability decreased by time in each group (p<0.05). The mean relative caspase-3 activity at 24 and 72 hours were: control group: 0.084±0.006 and 0.065±0.002, N-butyl cyanoacrylate with an area of dot/line: 0.940±0.037/0.924±0.053 and 0.999±0.072/1.056±0.015, 2-octyl cyanoacrylate with an area of dot/line: 0.900±0.044/0.928±0.018 and 0.989±0.084/0.999±0.072. The mean relative caspase-3 activity was higher than control group in each group at each time interval (p<0.05) and activity increased by time in N-butyl cyanoacrylate line and in 2-octyl cyanoacrylate line groups (p<0.05). CONCLUSION: Our findings indicate that N-butyl cyanoacrylate and 2-octyl cyanoacrylate cause cytotoxicity in cell-culture media. We may also postulate that they induce apoptosis in cell-culture media.

Investigation of axonal regeneration of Triturus ivanbureschi by using physiological and proteomic strategies.

Peripheral nerve injuries are frequently observed and successful treatment depends mainly on the injury type, location of the damage, and the elapsed time prior to treatment. The regenerative capacity is limited only to the embryonic period in many mammalian tissues, but urodele amphibians do not lose this feature during adulthood. The main purpose of this study is to define the recovery period after serious sciatic nerve damage of a urodele amphibian, Triturus ivanbureschi. Experimental transection damage was performed on the sciatic nerves of T. ivanbureschi specimens. The recovery period of sciatic nerves were investigated by walking track analysis, electrophysiological recordings, and bottom-up proteomic strategies at different time points during a 35-day period. A total of 34 proteins were identified related to the nerve regeneration process. This study showed that the expression levels of certain proteins differ between distal and proximal nerve endings during the regeneration period. In distal nerve stumps, transport proteins, growth factors, signal, and regulatory molecules are highly expressed, whereas in proximal nerve stumps, neurite elongation proteins, and cytoskeletal proteins are highly expressed.

Investigation of survival and migration potential of differentiated cardiomyocytes transplanted with decellularized heart scaffold.

Mesenchymal stem cell-derived cardiomyocytes are employed as a source for myocardial cell transplantation as well as for tissue engineering in decellularized tissue scaffolds. The present study aimed at investigating the survival and migration potential of differentiated cardiomyocytes integrated to decellularized scaffolds after implantation into retroperitoneum of rats, and to assess the feasibility of their ectopic use for future cardiovascular tissue engineering. For this purpose, adipose tissue-derived mesenchymal stem cells (AdMSCs) were first isolated. Cells were labeled by bromodeoxyuridine (BrdU). Decellularized cardiac tissue scaffolds were acquired by application of ionic and non-ionic detergents and the labeled differentiated cells were seeded onto these tested decellularized scaffolds. After 1, 2, and 4 weeks of implantation, either cell free scaffold (CFS) or cell scaffold (CS) composites were examined by various techniques for ectopic migration potential of the implanted cells and interaction between the seeded cells on scaffolds. Throughout the first and second weeks of implantation, positively stained cells were observed in renal tissue samples. Observations, for cardiomyocytes-specific gene expression during weeks 1, 2, and 4, showed potential increased over each time period. A reverse transcription polymerase chain reaction (RT-PCR) results revealed an increased interaction between cells seeded on scaffolds, however CFS test groups showed no significant difference in gene expression. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 561-570, 2019.

Bone marrow derived mesenchymal stem cells ameliorate inflammatory response in an in vitro model of familial hemophagocytic lymphohistiocytosis 2.

BACKGROUND: Familial hemophagocytic lymphohistiocytosis 2 (FHL2) is the most common familial type of hemophagocytic lymphohistiocytosis with immune dysregulation. FHL2 patients have mutations in the perforin gene which cause overactivation and proliferation of cytotoxic T lymphocytes and natural killer cells. Perforin is the key component of the cytolytic granule response function of cytotoxic T lymphocytes and natural killer cells. Perforin dysfunction causes a cytotoxic immune deficiency with a clinical outcome of uncontrolled and continuous immune stimulation response. This excessive stimulation leads to continuous systemic inflammation and, ultimately, multiorgan failure. Radical therapy is hematopoietic stem cell transplantation which is limited by the availability of a donor. Exacerbations of inflammatory attacks require a palliative immunosuppressive regimen. There is a need for an alternative or adjuvant therapy to maintain these patients when immunosuppression is ineffective or a donor is not available. Beneficial actions of mesenchymal stem cells (MSCs) have been shown in autoimmune diseases in clinical trials and are attributed to their immune-modulatory properties. This study aimed to assess the immune-modulatory effect of MSCs in an in-vitro model of FHL2. METHODS: We generated a targeted mutation in the perforin gene of NK92 cells to create an in-vitro FLH2 model using Crispr/Cas technology. A coculture setup was employed to assess the immunomodulatory efficacy of MSCs. RESULTS: Engineered NK92 clones did not show PRF1 mRNA expression and failed to secrete perforin upon phorbol myristate acetate-ionomycin stimulation, providing evidence for a valid FHL2 model. Coculture media of the engineered cells were investigated for the abundance of several cytokines. Coculture with MSCs revealed a reduction in major proinflammatory cytokines and an induction in anti-inflammatory and immunomodulatory cytokines compared to the parental NK92 cells. CONCLUSIONS: This study shows the ameliorating effect of MSCs as an adjuvant immune modulator toward the therapy of FHL2 patients. MSCs are supportive therapy candidates for FHL2 patients under circumstances where prolonged immunosuppression is required to gain time before allogeneic hematopoietic stem cell transplantation.

Cellular localization and biological effects of 20nm-gold nanoparticles.

Gold nanoparticles (AuNPs) have recently emerged as prominent vehicles for many biomedical applications from sensing to delivery. The relevant literature contains conflicting data about the effects of AuNPs on living cells. The aim of present study is the synthesis and characterization of AuNPs at nanoscale, tracking their cellular localization and determining their effects on cell viability, migration and angiogenesis. Within this scope, 20 nm AuNPs were synthesized and characterized using various spectrometric techniques to determine their size, shape and surface properties such as charge and texture. Two main cell types including mouse fibroblast (L929) and human cervix adenocarcinoma (HeLa) were used in the study to compare the biological effects of colloidal gold on both non-cancer and cancer cells. AuNPs were allowed to interact with HeLa cells to determine their intracellular localization. AuNPs were mainly attached to the cell membrane/membranous compartments and to be captured in small amounts in cytoplasmic vacuoles or to be distributed freely in the cytosol. Scratch assay results showed that AuNPs reduced cancer cell migration especially at increasing concentrations. According to the chick chorioallantoic membrane assay, AuNPs exhibited strong anti-angiogenetic properties and can inhibit vascularization during angiogenesis. In addition, the MTT assay confirmed that AuNP-treated cells caused concentration dependent cytotoxic effects on both cell types. As a result, AuNPs not only have inhibitory effects on cancer cells, but also possess antiangiogenic activity, thus making them a multipotent agent for cancer therapy. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1708-1721, 2018.

Hyperoxic or hypoxic environment?

We read the article by Khan et al. (2017) in a recent issue of this journal with great interest. We would like to congratulate the authors for this report. In the article, the authors focused primarily on the characteristics of adiposederived mesenchymal stem cells (Ad-MSCs) by altering culture environment. The results of the study showed that culture medium containing 0.5% gelatin enhanced the proliferation rate, induced immunosuppression, and activated BMP-7 and the wnt/AXIN/ß-catenin pathway in Ad-MSCs. However, we believe there is a misunderstanding in the introduction section of the article. A review of the literature shows that certain characteristics of MSCs can be modified with altered culture environments or preconditioned incubation processes. Khan et al. also cited a review published by Song et al. in 2010, as mentioned in the Introduction. This study indicated that preconditioning MSCs under hypoxic conditions enhanced the activity of the MSCs, suggesting a new perspective for the cellular treatment of cardiac tissue damages. In this review, hypoxic conditions were shown to have cytoprotective effects for MSCs, regulated paracrine factors, and increased the VEGF secretion (Song et al., 2010). Likewise, several studies with different designs in the literature yielded similar results (Kadle et al., 2016; Ciria et al., 2017). Therefore, we believe that the term "hyperoxic conditions" mentioned in the introduction of Khan et al.'s article (in citation to the study of Song et al.) is confusing. We recommend that this erroneous term be corrected to prevent any misunderstanding for the readers. We believe that the authors of the article would regard our opinion as a contribution.

Decellularization of rat adipose tissue, diaphragm, and heart: a comparison of two decellularization methods.

Decellularization is a process that involves the removal of cellular material from the tissues and organs while maintaining the structural, functional, and mechanical properties of extracellular matrix. The purpose of this study was to carry out decellularization of rat adipose tissue, diaphragm, and heart by using two different methods in order to compare their efficiency and investigate proliferation profiles of rat adipose-tissue-derived mesenchymal stem cells (AdMSCs) on these scaffolds. Tissues were treated with an optimized detergent-based decellularization (Method A) and a freeze-and-thaw-based decellularization (Method B). AdMSCs were then seeded on scaffolds having a density of 2 × 105 cells/scaffold and AO/PI double-staining and MTT assays were performed in order to determine cell viability. In this study, which is the first research comparing two methods of decellularization of an adipose tissue, diaphragm, and heart scaffolds with AdMSCs, Method A provided efficient decellularization in these three tissues and it was shown that these porous scaffolds were cyto-compatible for the cells. Method B caused severe tissue damage in diaphragm and insufficient decellularization in heart whereas it also resulted in cyto-compatible adipose tissue scaffolds.

Effects of propolis on warfarin efficacy.

INTRODUCTION: Warfarin is commonly used to avoid thromboembolism, predominantly for cardiovascular pathologies. However, the consumption of several herbal products is not permitted during its use due to the associated interactions. Propolis is a popular phytotherapy product made by honey bees. The use of propolis has been dramatically increasing in recent times. AIM: To evaluate the possible interactions between propolis and warfarin in a mouse model with determination of the international normalized ratio (INR) values. MATERIAL AND METHODS: CD-1 mice were employed in the experimental model. The mice were warfarinized, and propolis was administered simultaneously. The INR values were obtained. All animals were sacrificed at the end of the study. RESULTS: The baseline INR value was 0.8 ±0.1. After 72 h, the INR value increased as expected. The INR value was 7.28 ±1.08 in the control group and 5.8 ±2.88 in the propolis group. At the end of the study, the INR value was 1.3 ±0.37. Propolis interacted with warfarin and caused a decrease in the INR value. CONCLUSIONS: Propolis interactions, especially with warfarin, should be kept in mind and further studied. Healthcare specialists should be aware of this possible interaction between warfarin and propolis and inform patients about it.

Effects of VEGF and MSCs on vascular regeneration in a trauma model in rats.

In the human body, vascular injuries that are caused by trauma, vessel lumen stenosis, and occlusions are often irreversible and can lead to sequelae formation as the vessels cannot reproduce fast enough. To solve this problem, the blood flow must be returned to the region as fast as possible. The adipose tissue contains progenitor cells with angiogenic potential and can be used to resolve the issue. In the present study, mesenchymal stem cells (MSCs) derived from rat adipose tissue, vascular endothelial growth factor (VEGF), and their mixture were applied on the dorsum of a rat, which was traumatized and its contribution to vascular regeneration was reviewed. No application was made to the control group. The results showed that the percentage of necrotic area was significantly lower in the MSC group than that of all the other groups. When the VEGF group was compared to the VEGF + MSCs, the percentage of necrotic area was observed to be similiar. However, VEGF showed effects only when a large quantites of VEGF was applied to the flap area. VEGF could not fully respond to the needs, whereas MSCs can produce VEGF according to the needs of tissue. This makes them superior to stem cells.

Characterization and cellular interaction of fluorescent-labeled PHEMA nanoparticles.

The aim of this study is to label the cells with polymeric nanoparticles properly and efficiently. For this purpose, acridine orange (AO)-loaded poly(2-hydroxyethyl methacrylate) (PHEMA) nanoparticles were synthesized by miniemulsion polymerization. PHEMA nanoparticles were characterized by zeta sizer, zeta potential, atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), fluorescence microscopy, Fourier transform infrared spectrophotometer (FTIR), and elemental analysis. In addition, the toxicity of the nanoparticles were investigated by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay.

Derivation, characterization and expansion of fetal chondrocytes on different microcarriers.

Fetal chondrocytes (FCs) have recently been identified as an alternative cell source for cartilage tissue engineering applications because of their partially chondrogenically differentiated phenotype and developmental plasticity. In this study, chondrocytes derived from fetal bovine cartilage were characterized and then cultured on commercially available Cytodex-1 and Biosilon microcarriers and thermosensitive poly(hydroxyethylmethacrylate)-poly(N-isopropylacrylamide) (PHEMA-PNIPAAm) beads produced by us. Growth kinetics of FCs were estimated by means of specific growth rate and metabolic activity assay. Cell detachment from thermosensitive microcarriers was induced by cold treatment at 4 °C for 20 min or enzymatic treatment was applied for the detachment of cells from Cytodex-1 and Biosilon. Although attachment efficiency and proliferation of FCs on PHEMA-PNIPAAm beads were lower than that of commercial Cytodex-1 and Biosilon microcarriers, these beads also supported growth of FCs. Detached cells from thermosensitive beads by cold induction exhibited a normal proliferative activity. Our results indicated that Cytodex-1 microcarrier was the most suitable material for the production of FCs in high capacity, however, 'thermosensitive microcarrier model' could be considered as an attractive solution to the process scale up for cartilage tissue engineering by improving surface characteristics of PHEMA-PNIPAAm beads.

Do resin cements alter action potentials of isolated rat sciatic nerve?

OBJECTIVES: The purpose of this study was to explore the effects dual-cure resin cements on nerve conduction. METHODS: Panavia F, RelyX ARC, and Variolink II polymerized either by light-emitting diode (LED) or quartz tungsten halogen (QTH) were used in the study (n=10). The conductance of sciatic nerves of 50 rats were measured before and after contact with the specimens for 1 h. RESULTS: The time-dependent change in nerve conductance and the comparison of LED versus QTH showed that differences between groups are significant (P<.05). For both polymerization techniques, pair-wise comparisons of resin cements showed that the nerve conductance between groups is different (P<.05). RelyX ARC elicited irreversible inhibition of compound action potentials (more than 50% change) and Panavia F and Variolink II polymerized by LED and QTH did not alter nerve conduction beyond physiologic limits. CONCLUSIONS: Resin cements may alter nerve conductance and even lead to neurotoxic effects.