Development of a 3D Collagen Model for the In Vitro Evaluation of Magnetic-assisted Osteogenesis

Abstract Magnetic stimulation has been applied to bone regeneration, however, the cellular and molecular mechanisms of repair still require a better understanding. A three-dimensional (3D) collagen model was developed using plastic compression, which produces dense, cellular, mechanically strong native collagen structures. Osteoblast cells (MG-63) and magnetic iron oxide nanoparticles (IONPs) were incorporated into collagen gels to produce a range of cell-laden models. A magnetic bio-reactor to support cell growth under static magnetic fields (SMFs) was designed and fabricated by 3D printing. The influences of SMFs on cell proliferation, differentiation, extracellular matrix production, mineralisation and gene expression were evaluated. Polymerase chain reaction (PCR) further determined the effects of SMFs on the expression of runt-related transcription factor 2 (Runx2), osteonectin (ON), and bone morphogenic proteins 2 and 4 (BMP-2 and BMP-4). Results demonstrate that SMFs, IONPs and the collagen matrix can stimulate the proliferation, alkaline phosphatase production and mineralisation of MG-63 cells, by influencing matrix/cell interactions and encouraging the expression of Runx2, ON, BMP-2 and BMP-4. Therefore, the collagen model developed here not only offers a novel 3D bone model to better understand the effect of magnetic stimulation on osteogenesis, but also paves the way for further applications in tissue engineering and regenerative medicine

The enhancement of CRISPR/Cas9 gene editing using metformin

The CRISPR/Cas9 technology is a revolutionary tool that can be used to edit the genome. Specifically, the genome of hematopoietic stem cells (HSCs) could be edited to correct monogenic blood disorders as well as produce immunotherapies. However, the efficiency of editing HSCs remains low. To overcome this hurdle, we set out to investigate the use of metformin, an FDA-approved drug, to enhance gene modification. We assessed the effect of metformin on the growth of two hematopoietic cell lines: a myeloid-erythroid leukemic cell line (K562 cells) representative of the myeloid population and an immortalized T lymphocyte cell line (Jurkat cells) representative of the lymphoid population. No significant difference in growth patterns was observed in concentrations up to 10 mM metformin in both cell lines. We then assessed the ability of two different concentrations of metformin (0.001 mM or 1 mM), based on our observations, to enhance both (1) the cutting efficiency of Cas9 and (2) the targeting efficiency with the use of a donor DNA repair template. The cutting efficiency of Cas9 was significantly enhanced in a total of five guide RNAs (four specific to a platelet locus and one specific to an erythroid locus) following treatment. In addition, an enhancement in targeting was observed with the use of a GFP-containing donor DNA repair template with both concentrations. Overall, a greater than two-fold increase in GFP expression was noted in cells treated with metformin. This suggests that metformin, an FDA-approved drug, could be added to existing protocols to enhance CRISPR/Cas9 gene editing

A dyadic perspective on parent-child dyadic coping in children with a chronic condition

Objective In this study, we examined the extent to which parents and their children with a chronic condition communicate their stress to one another and whether stress communication is associated with different forms of dyadic coping. Methods In a sample of 239 parent-child dyads, self-reported stress communication and different forms of perceived dyadic coping (i.e., emotion-oriented, problem-oriented, and negative dyadic coping) were assessed using a cross-sectional design. Results We first found that children's stress communication was positively associated with more positive (r = 0.28, p < .001) and less negative dyadic coping responses by children (r = −0.22, p < .001). Children's stress communication was also associated with more positive (r = 0.52, r = 0.45, p's < 0.001), and less negative dyadic coping responses by parents (r = −0.19, p < .001). Using dyadic data of children with a chronic condition and their parents, we found that more stress communication of children was associated with healthier coping responses of both children (perceived emotion-oriented dyadic coping: β = 0.23, p < .001) and parents (perceived emotion-oriented dyadic coping: β = 0.33, p < .001; perceived problem-oriented dyadic coping: β = 0.22, p < .001). Conclusion This underscores the importance of communication and adaptive coping strategies of parents and children in the context of a child's chronic condition. These findings may help us find ways to support children and their parents to optimally communicate about and deal with their stress

Divination, politics, and ancient near eastern empires

Introduction: This volume is the result of a session of the Prophetic Texts in their Ancient Contexts seminar at the 2011 national meeting of the Society of Biblical Literature in San Francisco..