Infrapatellar fat pads participate in the development of knee osteoarthritis in obese patients via the activation of the NF­κB signaling pathway.

The aim of the present study was to assess the activation of nuclear factor­κB (NF­κB) in the infrapatellar fat pads (IPFPs) of obese patients with knee osteoarthritis (KOA). For this purpose, 32 patients (22 obese patients with KOA and 10 patients with KOA with a healthy weight) treated with total knee arthroplasty (TKA) were selected. The expression levels of pro­inflammatory cytokines and adipocytokines, and the activation of NF­κB were detected in both the cases and controls by enzyme­linked immunosorbent assay (ELISA), western blot analysis and immunohistochemistry where appropriate. SPSS 18.0 software was used for statistical analysis to determine the correlation between obesity and the detected cytokine levels. It was found that in patients with KOA, the expression of leptin in the synovial fluid positively correlated with body mass index (BMI; P<0.05), and the expression of interleukin (IL)­6 in serum significantly correlated with the IL­1ß, leptin and tumor necrosis factor (TNF)­α levels (P<0.05). Furthermore, the expression of inflammatory cytokines and adipocytokines in IPFPs differed significantly between the obese and non­obese patients with KOA (P<0.05). By evaluating the expression of IKKß and IκBα and the nuclear translocation ability of p­p65, it was concluded that NF­κB signaling was activated to a higher degree in the IPFP tissues of obese patients with KOA than in those of patients with KOA with a healthy weight. On the whole, the findings of the present study suggested that the NF­κB signaling pathway was activated and that there were changes in the expression in levels of inflammatory cytokines and adipocytokines in the IPFP tissues of obese patients with KOA.

Bioprinting of Stem Cells: Interplay of Bioprinting Process, Bioinks, and Stem Cell Properties.

Combining the advantages of 3D bioprinting technology and biological characteristics of stem cells, bioprinting of stem cells is recognized as a novel technology with broad applications in biological study, drug testing, tissue engineering, regenerative medicine, etc. However, the biological performance and functional reconstruction of stem cells are greatly influenced by both the bioprinting process and post-bioprinting culture conditions, which are critical factors to consider for further applications. Here we review the recent development of stem cell bioprinting technology and conclude on the major factors regulating stem cell viability, proliferation, differentiation, and function from the aspects of the choice of bioprinting techniques, the modulation of bioprinting parameters, and the regulation of the stem cell niche in the whole lifespan of bioprinting practices. We aim to provide a comprehensive consideration and guidance regarding the bioprinting of stem cells for optimization of this promising technology in biological and medical applications.