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We have previously demonstrated that the rate of fluid shear stress (ΔSS) can manipulate the fate of mesenchymal stem cells (MSCs) to osteogenic or chondrogenic cells. However, whether ΔSS is comparable to other two means of induction medium and substrate stiffness that have been proven to be potent in differentiation control is unknown. In this study, we subjected MSCs to 1–7 days of osteogenic or chondrogenic chemical induction, or 1–4 days of 37 or 86 kPa of substrate stiffness induction, followed by 20 min of Fast ΔSS (0–0′) or Slow ΔSS (0–2′), which is a laminar FSS that linearly increased from 0 to 10 dyn/cm 2 in 0 (Fast) or 2 min (Slow) and maintained at 10 dyn/cm 2 for a total of 20 min. We found that 20 min of ΔSS could compete with 5 days' chemical and 2 days' substrate stiffness inductions. Our study confirmed that ΔSS is a powerful tool to control the differentiation of MSCs, which stressed the possible application in MSCs linage specification.

Low density lipoprotein (LDL)-apheresis therapy, which directly removes LDL from plasma by LDL-adsorbents in vitro is found to be clinically effective and safe to lower the LDL content in blood to prevent cardiovascular disease. Thus, developing excellent LDL adsorbents are becoming more and more attractive. Herein, functional Fe3O4@ZnO core-shell nanocomposites have been synthesized by a facile and eco-friendly two-step method. Not only do they possess high LDL adsorption (in PBS/plasma as well as on blood vessels) and favorable magnetic targeting ability but they can also be reused conveniently, which offer the Fe3O4@ZnO core-shell nanocomposites significant potential in the removal of LDL in vitro and in vivo.

Face to the limited repair capability of cartilage, we intended to find out signaling responsible for its matrix synthesis. Since spontaneous calcium response likes a label of cell status, here it was mapped in fresh and 24 hr cultured in situ chondrocytes under oxygen tensions of 20%, 5%, and 1% as well as mimic hypoxia conditions. The calcium source was traced using ethylene glycol-bis (β-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) and thapsigargin (TG) to treat cartilage. Their relative matrix of type II collagen (COLL-II) and glycosaminoglycan (GAG) were quantified after cultured for 3 and 7 days. We disclosed the specific fingerprint of calcium response and matrix deposition along the histological zones under various oxygen tensions, from which the effects of hyperoxia, normoxia, and hypoxia conditions on as well as the optimal oxygen tensions for maintenance of various zones of cartilage or chondrocytes were derived and obtained. Our results revealed that cytoplasm calcium was conducive to synthesize COLL-II but detrimental to synthesize GAG. These results provide correlation in addition to details of intracellular calcium response and matrix deposition in in situ cartilage along its histological zones under physiological oxygen tensions.

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