No abstract

Osteopontin (OPN), a secreted phosphoprotein, is a member of the small integrin-binding ligand N-linked glycoprotein (SIBLING) family of cell matrix proteins and participates in many biological activities. Studies have shown that OPN plays a role in bone metabolism and homeostasis. OPN not only is an important factor in neuronmediated and endocrine-regulated bone mass, but also is involved in biological activities such as proliferation, migration, and adhesion of several bone-related cells, including bone marrow mesenchymal stem cells, hematopoietic stem cells, osteoclasts, and osteoblasts. OPN has been demonstrated to be closely related to the occurrence and development of many bone-related diseases, such as osteoporosis, rheumatoid arthritis, and osteosarcoma. As expected, the functions of OPN in the bone have become a research hotspot. In this article, we try to decipher the mechanism of OPN-regulated bone metabolism and bone diseases.

No abstract

Optical vortices, a type of structured beam with helical phase wavefronts and ‘doughnut’-shaped intensity distributions, have been used to fabricate chiral structures in metals and spiral patterns in anisotropic polarization-dependent azobenzene polymers. However, in isotropic polymers, the fabricated microstructures are typically confined to non-chiral cylindrical geometry due to the two-dimensional ‘doughnut’-shaped intensity profile of the optical vortices. Here we develop a powerful strategy to realize chiral microstructures in isotropic material by coaxial interference of a vortex beam and a plane wave, which produces three-dimensional (3D) spiral optical fields. These coaxial interference beams are generated by designing contrivable holograms consisting of an azimuthal phase and an equiphase loaded on a liquid-crystal spatial light modulator. In isotropic polymers, 3D chiral microstructures are achieved under illumination using coaxial interference femtosecond laser beams with their chirality controlled by the topological charge. Our further investigation reveals that the spiral lobes and chirality are caused by interfering patterns and helical phase wavefronts, respectively. This technique is simple, stable and easy to perform, and it offers broad applications in optical tweezers, optical communications and fast metamaterial fabrication.

Inspired by natural creatures, the development of a device that collects water from fog represents an important research direction.

Nonlinear beam shaping refers to spatial reconfiguration of a light beam at a new frequency, which can be achieved by using nonlinear photonic crystals (NPCs). Direct nonlinear beam shaping has been achieved to convert second-harmonic waves into focusing spots, vortex beams, and diffraction-free beams. However, previous nonlinear beam shaping configurations in one-dimensional and two-dimensional (2D) NPCs generally suffer from low efficiency because of unfulfilled phase-matching condition. Here, we present efficient generations of second-harmonic vortex and Hermite-Gaussian beams in the recently-developed three-dimensional (3D) lithium niobate NPCs fabricated by using a femtosecond-laser-engineering technique. Since 3D χ(2) modulations can be designed to simultaneously fulfill the requirements of nonlinear wave-front shaping and quasi-phase-matching, the conversion efficiency is enhanced up to two orders of magnitude in a tens-of-microns-long 3D NPC in comparison to the 2D case. Efficient nonlinear beam shaping paves a way for its applications in optical communication, super-resolution imaging, high-dimensional entangled source, etc.

Bone marrow mesenchymal stem cells (BMMSC) have been shown to be recruited to the tumor microenvironment and exert a tumor‐promoting effect in a variety of cancers. However, the molecular mechanisms related to the tumor‐promoting effect of BMMSC on head and neck cancer (HNC) are not clear. In this study, we investigated Periostin (POSTN) and its roles in the tumor‐promoting effect of BMMSC on HNC. In vitro analysis of HNC cells cultured in BMMSC‐conditioned media (MSC‐CM) showed that MSC‐CM significantly promoted cancer progression by enhancing cell proliferation, migration, epithelial‐mesenchymal transformation (EMT), and altering expression of cell cycle regulatory proteins and inhibition of apoptosis. Moreover, MSC‐CM promoted the expression of POSTN and POSTN promoted HNC progression through the activation of the phosphoinositide 3‐kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling pathway. In a murine model of HNC, we found that BMMSC promoted tumor growth, invasion, metastasis and enhanced the expression of POSTN and EMT in tumor tissues. Clinical sample analysis further confirmed that the expression of POSTN and N‐cadherin were correlated with pathological grade and lymph node metastasis of HNC. In conclusion, this study indicated that BMMSC promoted proliferation, invasion, survival, tumorigenicity and migration of head and neck cancer through POSTN‐mediated PI3K/Akt/mTOR activation.

Background and Purpose: Melatonin is a neurohormone involved in bone homeostasis. Melatonin directs bone remodelling and the role of bone marrow mesenchymal stem cells (BMMSCs) in the regulating melatonin-mediated bone formationresorption balance remains undefined. Experimental Approach: Osteoporosis models were established and bone tissue and serum were collected to test the effects of melatonin on bone homeostasis. Melatonin receptors were knocked down, the NF-κB signalling pathway and receptor activator of NF-κB ligand (RANKL) expression were investigated. Communication between bone marrow mesenchymal stem cells and osteoclasts was detected with directcontact or indirect-contact system. Key Results: Bone loss and microstructure disorder in mice were reversed after melatonin treatment, as a result of anabolic and anti-resorptive effects. In vitro, a physiological (low) concentration of melatonin promoted the bone marrow mesenchymal stem cells, osteogenic lineage commitment and extracellular mineralization but had no impact on extracellular matrix synthesis. After MT knockdown, especially MT 2 , the positive effects of melatonin on osteogenesis were attenuated. The canonical NF-κB signalling pathway was the first discovered downstream signalling pathway after MT receptor activation and was found to be down-regulated by melatonin during osteogenesis. Melatonin suppressed BMMSC-mediated osteoclastogenesis by inhibiting RANKL production in BMMSCs and this effect only occurred when BMMSCs and osteoclast precursors were co-cultured in an indirect-contact manner. Conclusion and Implications: Our work suggests that melatonin plays a crucial role in bone balance, significantly accelerates the osteogenic differentiation of bone marrow mesenchymal stem cells by suppressing the MT 2 -dependent NF-κB signalling pathway, and down-regulates osteoclastogenesis via RANKL paracrine secretion. Abbreviations: ALP, alkaline phosphatase; BMD, bone mineral density; BMMs, bone marrow monocytes; BMMSCs, bone marrow mesenchymal stem cells; BV/TV, trabecular bone volume per total volume; Col-I, collagen I; CTX-I, C-terminal telopeptide α1 chain of type I collagen; H&E, haematoxylin and eosin; Mel, melatonin; OCN, osteocalcin; OPG, osteoprotegerin; OVX, ovariectomy; PINP, N-terminal propeptide of type I procollagen; RANK, receptor activator of NF-κB; RANKL, receptor activator of NF-κB ligand; TRAP, tartrate-resistant acid phosphatase; Tb. N, trabecular bone number; Tb. Sp, trabecular bone separation; Tb. Th, trabecular bone thickness; μCT, micro-CT.