To investigate the safety and efficacy of subretinal injection of human Wharton’s Jelly-derived mesenchymal stem cells (hWJ-MSCs) on retinal structure and function in Royal College of Surgeons (RCS) rats. RCS rats were divided into 2 groups: hWJ-MSCs treated group (n = 8) and placebo control group (n = 8). In the treatment group, hWJ-MSCs from healthy donors were injected into the subretinal space in one eye of each rat at day 21. Control group received saline injection of the same volume. Additional 3 animals were injected with nanogold-labelled stem cells for in vivo tracking of cells localisation using a micro-computed tomography (microCT). Retinal function was assessed by electroretinography (ERG) 3 days before the injection and repeated at days 15, 30 and 70 after the injection. Eyes were collected at day 70 for histology, cellular and molecular studies. No retinal tumor formation was detected by histology during the study period. MicroCT scans showed that hWJ-MSCs stayed localised in the eye with no systemic migration. Transmission electron microscopy showed that nanogold-labelled cells were located within the subretinal space. Histology showed preservation of the outer nuclear layer (ONL) in the treated group but not in the control group. However, there were no significant differences in the ERG responses between the groups. Confocal microscopy showed evidence of hWJ-MSCs expressing markers for photoreceptor, Müller cells and bipolar cells. Subretinal injection of hWJ-MSCs delay the loss of the ONL in RCS rats. hWJ-MSCs appears to be safe and has potential to differentiate into retinal-like cells. The potential of this cell-based therapy for the treatment of retinal dystrophies warrants further studies.

Mesenchymal stem cells are widely used in many pre-clinical and clinical settings. Despite advances in molecular technology; the migration and homing activities of these cells in in vivo systems are not well understood. Labelling mesenchymal stem cells with gold nanoparticles has no cytotoxic effect and may offer suitable indications for stem cell tracking. Here, we report a simple protocol to label mesenchymal stem cells using 80 nm gold nanoparticles. Once the cells and particles were incubated together for 24 h, the labelled products were injected into the rat subretinal layer. Micro-computed tomography was then conducted on the 15th and 30th day post-injection to track the movement of these cells, as visualized by an area of hyperdensity from the coronal section images of the rat head. In addition, we confirmed the cellular uptake of the gold nanoparticles by the mesenchymal stem cells using transmission electron microscopy. As opposed to other methods, the current protocol provides a simple, less labour-intensive and more efficient labelling mechanism for real-time cell tracking. Finally, we discuss the potential manipulations of gold nanoparticles in stem cells for cell replacement and cancer therapy in ocular disorders or diseases.

This study investigates cognitive and metacognitive strategies in learning oral Arabic among students at Universiti Teknologi MARA (UiTM), Malaysia. The concept of these strategies was derived from the self-regulated learning framework, which consists of five components, namely rehearsal, elaboration, organization, critical thinking, and metacognitive strategies. The purposes of this study are to investigate the level of cognitive and metacognitive strategies used (1) among UiTM students; (2) between students with different prior experiences, namely, some of them had an experience of 5 years in learning Arabic in secondary school (abbreviated by SWE) and some of them did not have any experience at all (abbreviated by SNE); (3) between students of different gender; and (4) between students with the interaction of different gender and prior experience. The sample of this study consists of 183 students and employs a questionnaire adapted from the Motivated Strategies for Learning Questionnaire (MSLQ). The study revealed that (1) all UiTM students used cognitive and metacognitive strategies at a moderate level; (2) SWE scored significantly higher than SNE in all five components of cognitive and metacognitive strategies; (3) females scored significantly higher than males in rehearsal, organization, and metacognitive strategies; and (4) there were no statistically significant differences noted in all components between students with the interaction of prior experience and gender. This study had some classroom implications. It suggested that some improvement and changes in learning oral Arabic should be made in terms of selecting learning materials, implementing oral Arabic activities, and learning tasks, which will stimulate the use of all strategies, as well as conducting proficiency tests instead of achievement tests. Students should also be exposed to the learning techniques which used all these strategies extensively and collaborative activities may be carried out among students with mixed prior experience and gender.