Evaluation of the restorative effect of ozone and chitosan-hyaluronic acid with and without mesenchymal stem cells on wound healing in rats.

This study evaluated the effect of ozone, chitosan-hyaluronic (Cs-HA) acid and mesenchymal stem cells (MSCs) on wound healing in rats. A total of 64 rats were randomly divided into four groups: control, ozone, Cs-HA + ozone and Cs-HA + ozone + MSCs. A 5 mm full-thickness wound was created on the back of each rat. The wound area was measured macroscopically on days 3, 5, 9 and 14. Tissue sections were prepared for histopathological evaluation of inflammation, collagen arrangement, neovascularization and epithelial tissue rearrangement. Macroscopic assessment showed differences in wound area on days 5, 9 and 14. Histopathological examination showed that the Cs-HA + ozone + MSCs and Cs-HA + ozone groups had significantly higher vascularization on day 3 compared to the ozone-treated and control groups. All treatment groups had significantly better collagen arrangement than the control group. On day 5, no significant difference was observed between different groups. On day 9, the inflammation level in the Cs-HA + ozone + MSCs group was significantly lower than in the other groups. All treatment groups had significantly better vascularization compared to the control group. On day 14, the rate of inflammation was significantly lower in the treatment groups than in the control group. Significantly higher collagen arrangement levels were observed in the Cs-HA + ozone and Cs-HA + ozone + MSCs groups compared to the control and ozone groups. All treatment groups had significantly better epithelial tissue rearrangement than the control group. Overall, the results of this study indicated that treatment with ozone, Cs-HA acid, Cs-HA and MSCs accelerated wound healing in rats. The effect of using Cs-HA acid with mesenchymal cells was better than the other types of treatment. Larger clinical trials are needed to assess these factors for improving chronic wound treatment.

Comparison Capacity of Collagen Hydrogel and Collagen/Strontium Bioglass Nanocomposite Scaffolds With and Without mesenchymal Stem Cells in Regeneration of Critical Sized Bone Defect in a Rabbit Animal Model.

Bone self-healing is limited and requires additional or external intervention to promote and accelerate bone regeneration. Therefore, the aim of this study was to investigate the potential capacity of hydrogel collagen (Co) nanocomposite alone, and in combination with 2% strontium (Co/BGSr2%) in presence of mesenchymal stem cells (MSCs) in full-thickness bone defect regeneration in the rabbit animal model. A total of 72 New Zealand white rabbits were randomly divided in 6 groups of 12 rabbits with full-thickness bone defect. In five groups, the bone defect was treated with MSC, Co, Co/BGSr2%, Co + MSCs, and Co/BGSr2% + MSCs. No treatment was done in the control group. The treatments were assessed radiographically, histopathologically, and immunohistochemically on days 14, 28, 42, and 56 post-treatment. The highest radiographical and histological scores were belonged to the Co/BGSr2% + MSC followed by Co + MSCs, Co/BGSr2%, Co, MSC, and the control groups. The highest and lowest mean expression level of osteocalcin was detected in the Co/BGSr2% + MSC and control groups by 28th dayof post-implantation, respectively. In contrast, the highest and lowest mean expression level of osteocalcin on day 56 post-implantation was belonged to the control and Co/BGSr2% + MSC, respectively. The Co/BGSr2% nanocomposite scaffold seeded with MSC can accelerate bone regeneration resulted from osteoblastic production of osteocalcin protein. Therefore, collagen hydrogel combined with 2% strontium in nanocomposite form is a suitable candidate scaffold for bone tissue engineering.

Dynamically Tunable Friction via Subsurface Stiffness Modulation.

Currently soft robots primarily rely on pneumatics and geometrical asymmetry to achieve locomotion, which limits their working range, versatility, and other untethered functionalities. In this paper, we introduce a novel approach to achieve locomotion for soft robots through dynamically tunable friction to address these challenges, which is achieved by subsurface stiffness modulation (SSM) of a stimuli-responsive component within composite structures. To demonstrate this, we design and fabricate an elastomeric pad made of polydimethylsiloxane (PDMS), which is embedded with a spiral channel filled with a low melting point alloy (LMPA). Once the LMPA strip is melted upon Joule heating, the compliance of the composite structure increases and the friction between the composite surface and the opposing surface increases. A series of experiments and finite element analysis (FEA) have been performed to characterize the frictional behavior of these composite pads and elucidate the underlying physics dominating the tunable friction. We also demonstrate that when these composite structures are properly integrated into soft crawling robots inspired by inchworms and earthworms, the differences in friction of the two ends of these robots through SSM can potentially be used to generate translational locomotion for untethered crawling robots.

Comparison capacity of collagen hydrogel, mix-powder and in situ hydroxyapatite/collagen hydrogelscaffolds with and without mesenchymal stem cells and platelet-rich plasma in regeneration of critical sized bone defect in a rabbit animal model.

The aim of this study was to investigate the effect of developed collagen (Co) hydrogel (CH), powder-mixed hydroxyapatite/collagen (HA/Co) hydrogel and in situ synthesized HA/Co (In/HA/Co) hydrogel with or without mesenchymal stem cell (MSC) and platelet-rich plasma (PRP) on the regeneration of full-thickness critical size bone defect in the rabbit animal model. In the first step of this study, the scaffolds were synthesized and characterized using FTIR spectroscopy, X-ray diffraction, and scanning electron microcopy. In the second step or animal study, the radial bone defects were filled with the synthesized scaffolds with and without MSC and PRP. One hundred sixty one year-old New Zealand white male rabbits were randomly divided in 16 groups of 10 rabbits including control with bone defect without treatment, In/HA/Co, HA/Co, CH, PRP, MSC, CH + PRP, HA/Co, In/HA/Co + PRP, HA/Co + PRP, CH + MSC, In/HA/Co + MSC, HA/Co + MSC, CH + PRP + MSC, In/HA/Co + PRP + MSC, and HA/Co + PRP + MSC. The created defects were filled using the constructed scaffolds alone or seeded with MSCs, with and without PRP injection. The treatments were assessed using histopathological, immunohistochemical and rediographical analysis on days 14, 28, 42, 56 post-treatment. The plate-like HA particles were distributed homogeneously in the in situ HA/Co scaffold compared to the HA/Co scaffold and had a similar structure to bone with carbonated plate-like HA particles and nanofibrilated Co matrix. In situ HA/Co nanocomposite seeded with MSC and enriched by PRP can accelerate bone regeneration resulted from osteoblastic production of osteocalcin protein. Therefore, in situ HA/Co hydrogel seeded with MSC and PRP can be a new approach for bone tissue engineering.

Effects of concurrent use of royal jelly with hydroxyapatite on bone healing in rabbit model: radiological and histopathological evaluation.

BACKGROUND: Bone grafts have been used to enhance bone fracture healing in orthopedic surgery. Bone grafts enhance bone healing either by mechanical support or acting as a scaffold for bone formation. Fresh autograft is the most effective biomaterial because it is histocompatible with less complication about transmissible disease. Hydroxyapatite is a well-established material for bone repair and very comparable to natural apatite providing a strong biomechanical interlock with host tissue. Royal jelly is the principal food for the honeybee queen. This biomaterial has been demonstrated to have several pharmacological activities, such as antiallergic, antitumor and anti-inflammatory effects. OBJECTIVES: This study was design to evaluate the effect of concurrent using of Royal jelly with hydroxyapatite on bone healing in rabbit model. METHODS: 15 adult rabbits weighting approximately 2 kg had been used. They were divided into three groups randomly. In first group (N = 5) mid radius bone defect created and left empty. The second group (N = 5) filled with hydroxy apatite alone and the last group (N = 5) filled with royal jelly and hydroxy apatite combination. Radiological evaluation performed on days14th, 28th and 42nd after operation. Histopathological evaluation was done on 56th postoperative day. RESULTS: Radiological evaluation showed significant superior bone healing in hydroxyapatite and hydroxyapatite-Royal jelly groups in comparison to control group. Control group was the inferior group between three groups. There were not any significant differences between three groups in histopathological group. CONCLUSION: In conclusion our study showed the best results with using the hydroxyl apatite and Royal-jelly group because they provide not only scaffold for bone healing but also do, they provide some osteoinduction materials for bone healing.

Switchable Adhesion via Subsurface Pressure Modulation.

Materials and devices with tunable dry adhesion have many applications, including transfer printing, climbing robots, and gripping in pick-and-place processes. In this paper, a novel soft device to achieve dynamically tunable dry adhesion via modulation of subsurface pneumatic pressure is introduced. Specifically, a cylindrical elastomer pillar with a mushroom-shaped cap and annular chamber that can be pressurized to tune the adhesion is investigated. Finite element-based mechanics models and experiments are used to design, understand, and demonstrate the adhesion of the device. Specifically, the device is designed using mechanics modeling such that the pressure applied inside the annular chamber significantly alters the stress distribution at the adhered interface and thus changes the effective adhesion strength. Devices made of polydimethylsiloxane (PDMS) with different elastic moduli were tested against glass, silicon, and aluminum substrates. Adhesion strengths (σ0) ranging from ∼37 kPa (between PDMS and glass) to ∼67 kPa (between PDMS and polished aluminum) are achieved for the nonpressurized state. For all cases, regardless of the material and roughness of the substrates, the adhesion strength dropped to 40% of the strength of the nonpressurized state (equivalent to a 2.5× adhesion switching ratio) by increasing the chamber pressure from 0.3σ0 to 0.6σ0. Furthermore, the strength drops to 20% of the unpressurized strength (equivalent to a 5× adhesion switching ratio) when the chamber pressure is increased to σ0.

In vivo assessment of a nanofibrous silk tube as nerve guide for sciatic nerve regeneration.

A nanofibrous silk nerve conduit has been evaluated for its efficiency based on the promotion of peripheral nerve regeneration in rats. The designed tubes with or without Schwann cells were implanted into a 10 mm gap in the sciatic nerves of the rats. Four months after the surgery, the regenerated nerves were monitored and evaluated by macroscopic assessments and histology. The results demonstrated that the nanofibrous grafts, especially in the presence of Schwann cells, enabled reconstruction of the rat sciatic nerve trunk with a restoration of nerve continuity and formation of nerve fibres with myelination. Histological data demonstrated the presence of Schwann and glial cells in regenerated nerves. This study strongly supports the feasibility of using artificial nerve grafts for peripheral nerve regeneration by bridging large defects in a rat model.

Leakage fault detection in Electro-Hydraulic Servo Systems using a nonlinear representation learning approach.

Electro-Hydraulic Servo Systems (EHSS) are employed as actuators to track the desired trajectory and exert force in heavy-duty industrial applications. The EHSS is often prone to problems such as leakage and actuator seal damage during the course of its utilization. These faults which cannot be directly detected from current sensor values, can eventually result in complications and degrade control performance. The goal of this research is to use representation learning concepts to detect these faults with decreased complexity. The objective is to find a nonlinear mapping to transform raw data into another space in which classification becomes easier. The data are driven from the hydraulic supply pressure signal. To find the mapping, a custom-built optimization algorithm is proposed along with a suitable cost function to carry out the search for the new representation. The performance of the resulting transformation is tested in an experimental setting to show the merits of the proposed method.

Enhanced sciatic nerve regeneration by human endometrial stem cells in an electrospun poly (ε-caprolactone)/collagen/NBG nerve conduit in rat.

In recent years, for neurodegenerative diseases therapy, research has focused on the stem cells therapy. Due to promising findings in stem cell therapy, there are various sources of stem cells for transplantation in human. The aim of this study was to evaluate sciatic nerve regeneration in the rat after nerve transaction followed by human endometrial stem cells (hEnSCs) treatment into poly (e-caprolactone)/collagen/nanobioglass (PCL/collagen/NBG) nanofibrous conduits. After treatment of animals, the performance in motor and sensory tests, showed significant improvement in rats treated with hEnSCs as an autograft. H&E images provided from cross-sectional and, longitudinal-sections of the harvested regenerative nerve as well as immunohistochemistry results indicated that regenerative nerve fibres had been formed and accompanied with new blood vessels in the conduit cell group. Due to the advantage of high surface area for cell attachment, it is reported that this electrospun nerve conduit could find more application in cell therapy for nerve regeneration in future, to further improve the functional regeneration outcome, especially for longer nerve defect restoration. In conclusion, our results suggest that the PCL/collagen/NBG nanofibrous conduit filled with hEnSCs is a suitable strategy to improve nerve regeneration after a nerve transaction in rat.

Effects of tail fat on recovery times of anesthesia with isoflurane in fat-tailed Iranian Lori-Bakhtiyari lambs.

In the present study, the effect of tail fat on recovery times in intact sheep and sheep with a ligated median sacral artery following similar anesthetic exposure with isoflurane was investigated. This study was performed using seven healthy fat-tailed Iranian Lori-Bakhtiyari ewe lambs. The lambs were anesthetized twice at two week intervals (the experiment was performed in two stages). After mask induction with isoflurane in 100% oxygen, sheep were intubated and anesthesia was maintained for 4 hr using a rebreathing system. Induction and extubation times and time to sternal recumbency and attempts to stand were recorded during anesthetic induction and recovery (Stage 1). Two weeks later, prior to the second anesthesia, the median sacral artery (MSA) was ligated under epidural anesthesia in sheep. All sheep were anesthetized as mentioned above (Stage 2). No significant differences were observed for the induction time between two stages (p > 0.05) but extubation, sternal recumbency and attempts to stand times were significantly longer in intact sheep (Stage 1) after 4 hr anesthesia with isoflurane (p < 0.05). Recovery time was decreased following MSA ligation in fat-tailed sheep, which suggested that body fat had a major role in the recovery time of isoflurane in sheep. We developed an animal model to investigate fat drug solubility of isoflurane gas. Therefore, using less-soluble in fat anesthetics is better than high-soluble anesthetics for prolonged anesthesia to decrease postoperative complication in obese patient.