Enhanced Osteogenic Differentiation of Pluripotent Stem Cells via γ-Secretase Inhibition

Bone healing is a complex, well-organized process. Multiple factors regulate this process, including growth factors, hormones, cytokines, mechanical stimulation, and aging. One of the most important signaling pathways that affect bone healing is the Notch signaling pathway. It has a significant role in controlling the differentiation of bone mesenchymal stem cells and forming new bone. Interventions to enhance the healing of critical-sized bone defects are of great importance, and stem cell transplantations are eminent candidates for treating such defects. Understanding how Notch signaling impacts pluripotent stem cell differentiation can significantly enhance osteogenesis and improve the overall healing process upon transplantation. In Rancourt’s lab, mouse embryonic stem cells (ESC) have been successfully differentiated to the osteogenic cell lineage. This study investigates the role of Notch signaling inhibition in the osteogenic differentiation of mouse embryonic and induced pluripotent stem cells (iPS). Our data showed that Notch inhibition greatly enhanced the differentiation of both mouse embryonic and induced pluripotent stem cells.

Cytokine Directed Chondroblast Trans-Differentiation: JAK Inhibition Facilitates Direct Reprogramming of Fibroblasts to Chondroblasts

Osteoarthritis (OA) is a degenerative disease of the hyaline articular cartilage. This disease is progressive and may lead to disability. Researchers proposed many regenerative approaches to treat osteoarthritis, including stem cells. Trans-differentiation of a fully differentiated cell state directly into another different differentiated cell state avoids the disadvantages of fully reprogramming cells to induced pluripotent stem cells (iPSCs) in terms of faster reprogramming of the needed cells. Trans-differentiation also reduces the risk of tumor formation by avoiding the iPSC state. OSKM factors (Oct4, Sox2, Klf4, and cMyc) accompanied by the JAK-STAT pathway inhibition, followed by the introduction of specific differentiation factors, directly reprogrammed mouse embryonic fibroblasts to chondroblasts. Our results showed the absence of intermediate induced pluripotent stem cell formation. The resulting aggregates showed clear hyaline and hypertrophic cartilage. Tumor formation was absent in sub-cutaneous capsules transplanted in SCID mice.

Validity of vision screening by school nurses in seven regions of Oman

We tested the validity of vision screening in schools in 7 regions of Oman in 2003. Two researchers tested 1719 randomly selected students in 4 school grades using the Snellen E acuity test. Trained school nurses had previously screened 182 233 students. The visual status recorded in the 2 screenings was compared. Sensitivity of screening by nurses was 68.34% (95% CI: 67.30-69.38) and specificity 99.23% (95% CI: 99.19-99.27). The positive predictive value was 85.42% (95% CI: 84.63-86.21) and negative predictive value was 97.93% (95% CI: 97.87-98.00). The sensitivity of the vision test was significantly higher in females, older students and in North Sharqiya region. In general, the vision screening of school students in Oman has satisfactory validity. Periodic training of nurses and supervision of the screening procedures could improve its sensitivity. Underlying causes of the high numbers of false negative cases should be further investigated.

Cost-effectiveness of audiometric screening of first-year preparatory pupils in Dhofar Region, Oman

Audiometric screening was conducted in Dhofar region to study the magnitude of ear problems and cost-effectiveness of screening first-year preparatory-school children in Oman. None of the 1894 pupils had otitis media with effusion or sensory neuronal hearing loss. Six children (0.32%) had impacted wax, 4 (0.21%) chronic suppurative otitis media and 2 (0.11%) dry perforation of eardrum. In all, 14 children (0.74%) with suspected hearing impairment were referred to a specialist but only 2 attended. Physicians and nurses spent 8-10 minutes for ear examination per child for a yield of less than 1%. The screening expenditure was US$ 5 per pupil. As the prevalence of serious ear conditions was low, we conclude that expanding the audiometric screening of schoolchildren to first-year preparatory pupils is not cost-effective.