Nanovibrational stimulation for 3D osteogenesis in biphasic 3D scaffold; a new option for bone tissue engineering

In our centre, we had developed nanovibrational bioreactor generating nanoscale vibration by piezo actuator for bone tissue engineering. Recently, nanovibrational stimulation (NS; 30 nm at 1000 Hz) showed the success of osteogenic induction in mesenchymal stem cells (MSCs) seeded collagen hydrogel without chemical supplement. However, culturing MSCs in the collagen hydrogel for long term NS stimulation in NS bioreactor is challenging due to its mechanical properties. The principle aim of this thesis is to develop the scaffold for nanovibrational bioreactor which is suitable for surgical application. Three strategies including ingel scaffolds, collagen concentration optimization and genipin crosslinking were trialled which aimed to improve hydrogel stiffness and handleability, possess biocompatibility and allow NS force transmission. The role of high amplitude stimulation (90 nm at 1000 Hz) on 3D osteogenesis was also studied. Interestingly, increasing NS amplitude successfully enhanced 3D osteogenesis through multiple pathways and it was biologically safe. Metabolomics during NS revealed the evidence of low level of reactive oxygen species production and inflammation which was controlled in physiological level through multiple intracellular signals such as redox balancing, NFkB and MAPK pathways. To propose the technique how to use NS induced MSCs for clinics, MSCs seeded biphasic scaffolds compositing collagen hydrogels and freeze dried collagen sponges were developed. Cell-hydrogel-sponge composite (CHSC) was reproducible, handleable and biologically safe. CHSC allowed a good fidelity of NS. NS with high amplitude stimulation successfully induced 3D osteogenesis. NS protocol in CHSC was optimized in order to identify a stimulating duration which can induce osteogenesis without phenotypic reversibility. Interestingly, two-week stimulation possibly committed MSCs in the preosteoblast stage

Periodic assessment of (ET-1) and Nitric Oxide (NO) in hypertensive disorders of pregnancy (HDP)

INTRODUCTION Hypertensive Disorders of Pregnancy (HDP) is an independent risk factor of cardiovascular (CVS) disease. Endothelin-1 (ET-1), a potent vasoconstrictor, has been identified as a pivotal mediator in both essential hypertension and HDP. Disturbances in Nitric Oxide (NO) bioavailability found in endothelial dysfunction may increase susceptibility to cardiovascular diseases. METHODOLOGY Thirty six pregnant women at 30-36 weeks period of gestation from the following categories (i) pregnancy induced hypertension (PIH) (ii) chronic hypertension during pregnancy (CH) and (iii) normal pregnant women (Control). Blood pressure indices measurements and sample collection was done at antepartum (30-36 weeks), post partum (8 weeks and 12 weeks). Endothelin-1 and serum NO were measured using the Human ET-1 (Endothelin-1) and NO ELISA Kit. RESULTS All blood pressure indices were significantly higher in HDP patients compared to control during antenatal and post partum periods. Serum ET-1 was significantly higher in patients with HDP compared to control during antenatal until 3 months post partum. This was accompanied by significantly lower levels of serum NO in HDP patients. CONCLUSION Persistently high levels of ET-1 and low levels of NO up to 3 months post partum in patients with history of HDP indicate presence of persistent endothelial dysfunction despite BP normalisation in PIH patients. Long term NO/ET-1 imbalance may account for the increased CVS disease risk

Low magnitude high frequency vibration promotes adipogenic differentiation of bone marrow stem cells via P38 MAPK signal

<div><p>Low magnitude high frequency vibration (LMHFV) has been mainly reported for its influence on the musculoskeletal system, particularly the bone tissue. In the bone structure, osteogenic activity is the main focus of study with regards to LMHFV. However, adipogenesis, another important mode of differentiation in the bone marrow cavity that might be affected by LMHFV, is much less researched. Furthermore, the molecular mechanism of how LMHFV influences adipogenesis still needs to be understood. Here, we tested the effect of LMHFV (0.3g, 40 Hz, amplitude: 50μm), 15min/d, on multipotent stem cells (MSCs), which are the common progenitors of osteogenic, chondrogenic, adipogenic and myogenic cells. It is previously shown that LMHFV promotes osteogenesis of MSCs. In this study, we further revealed its effect on adipo-differentiation of bone marrow stem cells (BMSCs) and studied the underlying signaling pathway. We found that when treated with LMHFV, the cells showed a higher expression of PPARγ, C/EBPα, adiponectin and showed more oil droplets. After vibration, the protein expression of PPARγ increased, and the phosphorylation of p38 MAPK was enhanced. After treating cells with SB203580, a specific p38 inhibitor, both the protein level of PPARγ illustrated by immunofluorescent staining and the oil droplets number, were decreased. Altogether, this indicates that p38 MAPK is activated during adipogenesis of BMSCs, and this is promoted by LMHFV. Our results demonstrating that specific parameters of LMHFV promotes adipogenesis of MSCs and enhances osteogenesis, highlights an unbeneficial side effect of vibration therapy used for preventing obesity and osteoporosis.</p></div