Transcriptome Analysis of MSC and MSC-Derived Osteoblasts on Resomer? LT706 and PCL: Impact of Biomaterial Substrate on Osteogenic Differentiation

Background

Mesenchymal stem cells (MSC) represent a particularly attractive cell type for bone tissue engineering because of their ex vivo expansion potential and multipotent differentiation capacity. MSC are readily differentiated towards mature osteoblasts with well-established protocols. However, tissue engineering frequently involves three-dimensional scaffolds which (i) allow for cell adhesion in a spatial environment and (ii) meet application-specific criteria, such as stiffness, degradability and biocompatibility.

Methodology/Principal Findings

In the present study, we analysed two synthetic, long-term degradable polymers for their impact on MSC-based bone tissue engineering: PLLA-co-TMC (Resomer® LT706) and poly(ε-caprolactone) (PCL). Both polymers enhance the osteogenic differentiation compared to tissue culture polystyrene (TCPS) as determined by Alizarin red stainings, scanning electron microscopy, PCR and whole genome expression analysis. Resomer® LT706 and PCL differ in their influence on gene expression, with Resomer® LT706 being more potent in supporting osteogenic differentiation of MSC. The major trigger on the osteogenic fate, however, is from osteogenic induction medium.

Conclusion

This study demonstrates an enhanced osteogenic differentiation of MSC on Resomer® LT706 and PCL compared to TCPS. MSC cultured on Resomer® LT706 showed higher numbers of genes involved in skeletal development and bone formation. This identifies Resomer® LT706 as particularly attractive scaffold material for bone tissue engineering.     

The role of endoplasmic reticulum stress in emphysema results from cigarette smoke exposure

Apoptosis is of considerable importance in the pathogenesis of emphysema, and recent studies show that endoplasmic reticulum (ER) stress is involved in emphysema. In our research, we investigated the role of protein kinase RNA (PKR)-like ER kinase (PERK)/ eukaryotic initiation factor 2 alpha (eIF2α) pathway, the CCAAT enhancer-binding protein-homologous protein (CHOP) expression, caspase-12 activation and apoptosis in emphysema results from cigarette smoke (CS) exposure. Expression of phosphorylated-PERK (p-PERK), phospholated-eIF2α (p-eIF2α),CHOP and caspase-12 as well as the apoptosis rate are remarkably increased in rats after exposure to 2 months CS compared with control rats, significantly elevated in rats exposed to 4 months CS over rats exposed only to 2 months CS, and slightly decreased in ex-smoking rats in contrast to rats exposed to 4 months CS. Taken together, our results show that CS induces ER stress in lung epithelial cells, which may subsequently lead to lung injury in rats, and this might be a novel target for protection of pulmonary epithelial cells from ER stress injury in emphysema.     

Integrating spread dynamics and economics of timber production to manage Chinese tallow invasions in southern U.S. forestlands

Economic costs associated with the invasion of nonnative species are of global concern. We estimated expected costs of Chinese tallow (Triadica sebifera (L.) Small) invasions related to timber production in southern U.S. forestlands under different management strategies. Expected costs were confined to the value of timber production losses plus costs for search and control. We simulated management strategies including (1) no control (NC), and control beginning as soon as the percentage of invaded forest land exceeded (2) 60 (Low Control), (3) 25 (Medium Control), or (4) 0 (High Control) using a spatially-explicit, stochastic, bioeconomic model. With NC, simulated invasions spread northward and westward into Arkansas and along the Gulf of Mexico to occupy ≈1.2 million hectares within 20 years, with associated expected total costs increasing exponentially to ≈$300 million. With LC, MC, and HC, invaded areas reached ≈275, 34, and 2 thousand hectares after 20 years, respectively, with associated expected costs reaching ≈$400, $230, and $200 million. Complete eradication would not be cost-effective; the minimum expected total cost was achieved when control began as soon as the percentage of invaded land exceeded 5%. These results suggest the importance of early detection and control of Chinese tallow, and emphasize the importance of integrating spread dynamics and economics to manage invasive species.     

Unusual long-chain N-acyl homoserine lactone production by and presence of quorum quenching activity in bacterial isolates from diseased tilapia fish

Growth-dependent cell-cell communication termed quorum sensing is a key regulatory system in bacteria for controlling gene expression including virulence factors. In this study five potential bacterial pathogens including Bacillus sp. W2.2, Klebsiella sp. W4.2, Pseudomonas sp. W3 and W3.1 and Serratia sp. W2.3 were isolated from diseased Tilapia fish in Malaysia, supplied by the leading global fish supplier. Proteolytic activity assays confirmed that with the exception of Klebsiella sp. W4.2, all isolates showed distinct proteolytic activity. Furthermore Bacillus sp. W2.2 and Pseudomonas sp. strains W3 and W3.1 also displayed haemolytic activity. By using high resolution liquid chromatography mass spectrometry, we revealed the presence of unusually long-chain N-(3-oxohexadecanoyl)-homoserine lactone (3-oxo-C16-HSL) from Pseudomonas sp. W3.1 and N-dodecanoyl-homoserine lactone (C12-HSL) from Serratia sp. W2.3, respectively. Interestingly, Pseudomonas sp. W3.1 also produced a wide range of Pseudomonas quinolone signalling (PQS) molecules. Pseudomonas sp. W3 did not show any quorum sensing properties but possessed quorum quenching activity that inactivated AHLs. This study is the first documentation that shows unusual long-chain AHLs production in Serratia sp. and Pseudomonas sp. isolated from diseased fish and the latter also produce a wide range of PQS molecules.     

Progression of Cartilage Degradation, Bone Resorption and Pain in Rat Temporomandibular Joint Osteoarthritis Induced by Injection of Iodoacetate

Background

Osteoarthritis (OA) is an important subtype of temporomandibular disorders. A simple and reproducible animal model that mimics the histopathologic changes, both in the cartilage and subchondral bone, and clinical symptoms of temporomandibular joint osteoarthritis (TMJOA) would help in our understanding of its process and underlying mechanism.

Objective

To explore whether injection of monosodium iodoacetate (MIA) into the upper compartment of rat TMJ could induce OA-like lesions.

Methods

Female rats were injected with varied doses of MIA into the upper compartment and observed for up to 12 weeks. Histologic, radiographic, behavioral, and molecular changes in the TMJ were evaluated by light and electron microscopy, MicroCT scanning, head withdrawal threshold test, real-time PCR, immunohistochemistry, and TUNEL assay.

Results

The intermediate zone of the disc loosened by 1 day post-MIA injection and thinned thereafter. Injection of an MIA dose of 0.5 mg or higher induced typical OA-like lesions in the TMJ within 4 weeks. Condylar destruction presented in a time-dependent manner, including chondrocyte apoptosis in the early stages, subsequent cartilage matrix disorganization and subchondral bone erosion, fibrosis, subchondral bone sclerosis, and osteophyte formation in the late stages. Nociceptive responses increased in the early stages, corresponding to severe synovitis. Furthermore, chondrocyte apoptosis and an imbalance between anabolism and catabolism of cartilage and subchondral bone might account for the condylar destruction.

Conclusions

Multi-level data demonstrated a reliable and convenient rat model of TMJOA could be induced by MIA injection into the upper compartment. The model might facilitate TMJOA related researches.     

Efficiency of New Dose Escalation Designs in Dose-Finding Phase I Trials of Molecularly Targeted Agents

Background

Statistical simulations have consistently demonstrated that new dose-escalation designs such as accelerated titration design (ATD) and continual reassessment method (CRM)-type designs outperform the standard “3+3” design in phase I cancer clinical trials.

Methods

We evaluated the actual efficiency of different dose escalation methods employed in first-in-human phase I clinical trials of targeted agents administered as single agents published over the last decade.

Results

Forty-nine per cent of the 84 retrieved trials used the standard “3+3” design. Newer designs used included ATD in 42%, modified CRM [mCRM] in 7%, and pharmacologically guided dose escalation in 1%. The median numbers of dose levels explored in trials using “3+3”, ATD and mCRM designs were 6, 8 and 10, respectively. More strikingly, the mean MTD to starting dose ratio appeared to be at least twice as high for trials using mCRM or ATD designs as for trials using a standard “3+3” design. Despite this, the mean number of patients exposed to a dose below the MTD was similar in trials using “3+3”, ATD and mCRM designs.

Conclusion

Our results support a more extensive implementation of innovative dose escalation designs such as mCRM and ATD in phase I cancer clinical trials of molecularly targeted agents.     

Thermal sensation at index finger while applying external pressure at upper arm

In this study we focused on thermal sensation at fingertip under the influence of applied external pressure via a tourniquet at the upper arm. The perceived thermal sensation has found to be closely related to the skin temperature (Tsk) that is regulated by the skin blood flow (SkBF), whereas SkBF is easily influenced by external pressure. We thus hypothesized that the perceived thermal sensation, the Tsk and SkBF form such a cross-coupled triad that jointly affects our feeling of thermal comfort. Such interconnections among them were examined in this study using two protocols to investigate the perceived thermal sensation from a given heat stimulus under an exerted external pressure: (1) the SkBF and Tsk, at the right hand index finger under different external pressures at the right upper arm of one male subject, were monitored by a laser-Doppler flowmeter (LDF); (2) subjective thermal feelings (cold, normal and warm) at the right index fingertip of 10 test takers were recorded, while contacting a glass tube filled with water at different temperatures, with/without 50 mm Hg external pressure at the upper arm, while the temperatures of the glass tube and the index fingertip were recorded by an infrared camera. First, it is found that the SkBF and Tsk at the index fingertip reduced significantly with high external pressure applied at the upper arm, while the pressure from our daily clothing is not large enough to generate such an effect. Next, the applied pressure suppresses the variations in subjective sensory responses towards the thermal stimuli. Our hypothesis on the interconnections among the perceived thermal sensation, the Tsk and SkBF is thus confirmed. Overall, females appear more discerning to temperature change under the given conditions compared to males.