This study aimed to investigate the feasibility of the nanostructured 3D poly(lactide-co-glycolide) (PLGA) constructs, which are loaded with dexamethasone (DEX) and growth factor embedded heparin/poly(L-lysine) nanoparticles via a layer-by-layer system, to serve as an effective scaffold for nucleus pulposus (NP) tissue engineering. Our results demonstrated that the microsphere constructs were capable of simultaneously releasing basic fibroblast growth factor and DEX with approximately zero order kinetics. The dual bead microspheres showed no cytotoxicity, and promoted the proliferation of the rat mesenchymal stem cells (rMSCs) by lactate dehydrogenase assay and CCK-8 assay. After 4 weeks of cultivation in vitro, the rMSCs-scaffold hybrids contained significantly higher levels of sulfated GAG/DNA and collagen type II than the control samples. Moreover, quantitative real time PCR analysis revealed that the expression of disc-matrix proteins including collagen type II, aggrecan, and versican in the rMSCs-scaffold hybrids was significantly higher than that in the control group, whereas the expression of osteogenic differentiation marker (collagen type I) was decreased. Taken together, these data indicate that Dex/bFGF PLGA microspheres could be used as a scaffold to improve the rMSCs growth and differentiating into NP like cells, and reduce the inflammatory response for IVD tissue engineering.

The pathogenesis of low back pain is still elusive. Here, we proposed a new hypothesis that low pH is a possible cause of the development and progression of low back pain. We propose that low pH promotes the production of the inflammatory mediators and the depletion of proteoglycan in the damaged intervertebral disk. The inflammation response, evoked by the dorsal root ganglia, changes the delicate nutrient balance in the nucleus, resulting in a vicious cycle and leading to choronic back pain. Our hypothesis may explain many of the available clinical and experimental data on low back pain, thus it may help elucidate the pathogenesis of low back pain and improve clinical management.

Narcissistic self-sorting, namely that components are able to distinguish "self" from "nonself" during selfassembly, was accomplished via catenation by condensing multiple hydrazides and an aldehyde, or a hydrazide and multiple aldehydes in water. The underneath mechanism of this behavior relies on the corresponding homo [2]catenanes are thermodynamically more favored than their hetero counterparts, because the former containing two identical macrocyclic components are able to maximize the intercomponent noncovalent forces. One of these catenanes contains four 4-phenylpyridinium units, which are often considered barely luminescent due to intramolecular rotations and vibrations that lead to nonradiative annihilation of their excited states. These intramolecular motions, however, are restricted upon integrating 4-phenylpyridiniums within the catenane architecture. As a consequence, compared to its non-interlocked counterparts, this catenane exhibits enhanced uorescence, which represents a novel conceptual model for developing luminescent materials.

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