Printing bone in a gel: using nanocomposite bioink to print functionalised bone scaffolds

Free-form printing offers a novel biofabrication approach to generate complex shapes by depositing hydrogel materials within a temporary supportive environment. However, printed hydrogels typically lack the requisite mechanical properties and functionality of the desired tissue, limiting application and, more importantly, safety and efficacy of the implant. The study authors have developed an innovative nanoclay-based bioink to print high shape fidelity functional constructs for potential skeletal application. Laponite® (LAP) nanoclay was combined with gellan gum (GG) to generate a printable hydrogel that was highly stable in vitro, displayed limited swelling ability compared with the silicate-free control and remained stable over time. An agarose fluid gel was found to provide the requisite support for the deposition of the material ink and preservation of the printed structure before crosslinking. Printed C2C12 myoblasts remained viable and displayed extensive proliferation over 21 days in culture. Cell-laden scaffolds demonstrated functionality within 1 day of culture in vitro and that was preserved over 3 weeks. Analysis of absorption and release mechanisms from LAP-GG using model proteins (lysozyme and bovine serum albumin) demonstrated the retention capability of the clay-based materials for compound localisation and absence of burst release. Vascular endothelial growth factor ​was loaded within the agarose fluid gel and absorbed by the material ink via absorption during deposition. The 3D-printed constructs were implanted on the chorioallantoic membrane of a 10-day-old developing chick. Extensive and preferential vasculature infiltration was observed in LAP-GG-loaded vascular endothelial growth factor constructs compared with controls (p<0.01 and p<0.0001) after only 7 days of incubation. The current studies demonstrate, for the first time, the application of innovative LAP-GG 3D constructs in the generation of growth factor-loaded 3D constructs for potential application in skeletal tissue repair.

The cell in the ink: Improving biofabrication by printing stem cells for skeletal regenerative medicine

Recent advances in regenerative medicine have confirmed the potential to manufacture viable and effective tissue engineering 3D constructs comprising living cells for tissue repair and augmentation. Cell printing has shown promising potential in cell patterning in a number of studies enabling stem cells to be precisely deposited as a blueprint for tissue regeneration guidance. Such manufacturing techniques, however, face a number of challenges including; (i) post-printing cell damage, (ii) proliferation impairment and, (iii) poor or excessive final cell density deposition. The use of hydrogels offers one approach to address these issues given the ability to tune these biomaterials and subsequent application as vectors capable of delivering cell populations and as extrusion pastes. While stem cell-laden hydrogel 3D constructs have been widely established in vitro, clinical relevance, evidenced by in vivo long-term efficacy and clinical application, remains to be demonstrated. This review explores the central features of cell printing, cell-hydrogel properties and cell-biomaterial interactions together with the current advances and challenges in stem cell printing. A key focus is the translational hurdles to clinical application and how in vivo research can reshape and inform cell printing applications for an ageing population.

Influence of static magnetic fields up to 700 mT and dihydrochalcones on the antioxidant response in fibroblasts

The effects of a static magnetic field (SMF) and the dihydrochalcones phloretin and phloridzin on the redox homeostasis of fibroblasts were investigated. The aim of the present study was to determine the redox homeostasis of fibroblasts that were simultaneously exposed to a static magnetic field and the dihydrochalcones phloretin and phloridzin. The fibroblasts were cultured for 72 h in special magnetic test chambers at different moderate intensities (0.4, 0.55 and 0.7 T). In this report, the activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), glutathione transferase (GST); the concentrations of malondialdehyde (MDA), adenosine triphosphate (ATP) and total antioxidant status were measured using commercially available kits. We did not observe any impairment in the redox balance in cells in fibroblasts that were only exposed to static magnetic fields of different intensities or In fibroblast cultured with dihydrochalcones and exposed to static magnetic field increase the SOD, GPx, GST activities and MDA concentration. Our investigations revealed that the activities of SOD, GPx, GST and the concentration of MDA that were determined for the fibroblasts that were cultured with dihydrochalcones were higher in the presence of a static magnetic field. Our results indicated that exposure to SMF (0.7 T) with dihydrochalcones induces oxidative stress in fibroblasts.

Effect of static magnetic fields and phloretin on antioxidant defense system of human fibroblasts

The available evidence from in vitro and in vivo studies is deemed not sufficient to draw conclusions about the potential health effects of static magnetic field (SMF) exposure. Therefore, the aim of the present study was to determine the influence of static magnetic fields and phloretin on the redox homeostasis of human dermal fibroblasts. Control fibroblasts and fibroblasts treated with phloretin were subjected to the influence of static magnetic fields. Three chambers with static magnetic fields of different intensities (0.4, 0.55, and 0.7 T) were used in the study. Quantification of superoxide dismutase 1 (SOD1), superoxide dismutase 2 (SOD2), glutathione peroxidase 1 (GPX1), microsomal glutathione S-transferase 1 (MGST1), glutathione reductase (GSR), and catalase (CAT) messenger RNAs (mRNAs) was performed by means of real-time reverse transcription PCR (QRT-PCR) technique. Superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) activities were measured using a commercially available kit. No significant differences were found in SOD1, SOD2, GPX1, MGST1, GSR, and CAT mRNA levels among the studied groups in comparison to the control culture without phloretin and without the magnet. There were also no changes in SOD, GPx, and CAT activities. In conclusion, our study indicated that static magnetic fields generated by permanent magnets do not exert a negative influence on the oxidative status of human dermal fibroblasts. Based on these studies, it may also be concluded that phloretin does not increase its antioxidant properties under the influence of static magnetic fields. However, SMF-induced modifications at the cellular and molecular level require further clarification.

Influence of extremely low-frequency magnetic field on the activity of antioxidant enzymes during skin wound healing in rats

The aim of this study was to evaluate the activity of the antioxidant enzymes mitochondrial and cytosolic superoxide dismutase (EC 1.15.1.1), glutathione peroxidase (POX, EC 1.11.1.9) and glutathione S-transferase (EC 3.1.2.7), as well as the concentration of malone dialdehyde (MDA), as an indicator of lipid peroxidation rate in the liver tissue homogenates and blood serum of male rats exposed to extremely low-frequency magnetic field (ELF-MF) in order to improve the healing process of an experimental cut wound on the back of each animal. The exposure to ELF-MF with frequency 40 Hz and magnetic flux density 10 mT induced an increase in POX serum activity and a decrease in MDA contents in the liver tissue, which suggests the inhibition of phospholipid peroxidation and subsequent stabilization of cellular membranes, as a result of ELF-MF action. Based on the results obtained, it seems that ELF-MF could be a useful supplement in the complex treatment of prolonged wound healing, due to the activation of endogenous enzymatic antioxidant system.

Strategy for the treatment of chronic leg wounds: a new model in Poland

AIM

The aim of the present study was to implement and evaluate a system of care for patients with chronic leg ulceration (CLU) in Poland.

METHODS

All patients within two defined geographical areas in Poland were identified for inclusion in the study. A model of care was developed based on guidelines, including the appropriate education of health professionals treating patients, access to non-invasive methods to determine the ulcer aetiology, compression therapy in those with proven venous ulceration.

RESULTS

In total 309 patients were identified with CLU at the start of the study (120 men, 189 women). Both regions had a similar profile of patients having a median (IQR) duration of ulceration of 96 (30-168) months. Most (75.7%) patients were assessed using clinical signs and symptoms alone, with a mean (SD) number of treatments per week at 1.8 (1.9) visits. Two years after implementation, the numbers of patients had reduced to 205 (86 men, 119 women) a reduction of 33%. Post implementation more patients were treated at home (49.3% versus 19.5%) with a corresponding reduction in those seen at health centres (35.6% versus 63.3%). The mean (SD) number of visits was reduced to 1.3 (0.7). During implementation the healing rate at 30 weeks improved from 73.3% to 82.9%, with a corresponding reduction in amputations from 6.3% to 2.1%. While the cost per patient was higher post-implementation, the overall cost of treating patients within the service reduced from €3847 to €2913 per week.

CONCLUSION

The development and implementation of an evidence based system of care for patients with CLU in Poland is both clinically and cost effective. This may be used as a model for other regions of Poland.

The Quality of Local Anaesthesia Associated with Intravenous Administration of Ketoprofen in Radical Operations for Leg Varicose Veins

Objective:

To evaluate the use of intravenous ketoprofen administration during varicose vein surgery undertaken under local anaesthesia.

Setting:

Regional general hospital in Poland.

Patients:

One hundred and six patients presenting with primary long saphenous varicose veins, including those with skin changes and leg ulceration.

Interventions:

Patients underwent sapheno-femoral ligation and long saphenous stripping under local anaesthesia including femoral nerve block, having first received an intravenous infusion of ketoprofen.

Outcome measures:

Patients recorded their level of discomfort or pain on a five-point scale. Blood pressure and pulse were also recorded.

Results:

One hundred and two patients found the level of analgesia produced by this technique to be acceptable, and 75 reported no discomfort at all.

Conclusions:

The combined use of intravenous ketoprofen and local anaesthesia allowed the treatment of all patients with superficial venous incompetence irrespective of their fitness for general anaesthesia.