In order to study the effect of stress changes on cell adhesion, HUVEC, and MCF-7 cells were treated with simulated microgravity effect (SMG) and overloading (OL). Methods: Rotating Wall Vessel (2D-RWVS) bioreactor was used to create different culture conditions. In addition, the alteration of cell adhesion states, adhesion proteins, and relating factors of adhesion molecules under these two conditions were detected using cell adhesion assay, immunofluorescence, western blot, and qRT-PCR technology. Results: The results showed that the adhesion of cells decreased under SMG, while increased under OL. The expressions of integrin β1, paxillin, and E-cadherin under SMG condition were down-regulated as compared to that of the control group showing a time-dependent pattern of the decreasing. However, under OL condition, the expressions of adhesion proteins were up-regulated as compared to that of the control group, with a time-dependent pattern of increasing. EMT transcription factors Snail, twist, and ZEB1 were up-regulated under SMG while down-regulated under OL. Conclusion: Collectively our results indicated that cells could respond to stress changes to regulate the expressions of adhesion proteins and adapt their adhesion state to the altered mechanical environment. The altered cell adhesion in response to the mechanical stress may involve the changed expression of EMT-inducing factors, Snail, Twist, and ZEB1under the SMG/OL conditions.

Auricularia auricula polysaccharides used in Pinus koraiensis polyphenol encapsulation and delivery under weightlessness are rarely reported. In this study, an anionic polysaccharide fragment named AAP Iα with a molecular weight of 133.304 kDa was isolated and purified to construct a polyphenol encapsulation system. Nanoparticles named NPs-PP loaded with a rough surface for Pinus koraiensis polyphenol (PP) delivery were fabricated by AAP Iα and ε-poly-L-lysine (ε-PL). SEM and the DLS tracking method were used to observe continuous changes in AAP Iα, ε-PL and PP on the nanoparticles’ rough surface assembly, as well as the dispersion and stability. Hydrophilic, monodisperse and highly negative charged nanoparticles can be formed at AAP Iα 0.8 mg/mL, ε-PL 20 μg/mL and PP 80 μg/mL. FT-IR was used to determine their electrostatic interactions. Release kinetic studies showed that nanoparticles had an ideal gastrointestinal delivery effect. NPs-PP loaded were assembled through electrostatic interactions between polyelectrolytes after hydrogen bonding formation in PP-AAP Iα and PP-ε-PL, respectively. Colon adhesion properties and PP delivery in vivo of nanoparticles showed that NPs-PP loaded had high adhesion efficiency to the colonic mucosa under simulated microgravity and could enhance PP bioavailability. These results suggest that AAP Iα can be used in PP encapsulation and delivery under microgravity in astronaut food additives.

Background: Prolonged exposure to microgravity during spaceflight leads to significant bone loss. The phenomenon of weightlessness-induced bone loss (WIBL) continues to intensify as the flight time increases and this has attracted considerable attention of scholars. Methods: In this study, proteomic analysis was performed to identify potential signaling pathways involved in WIBL. Subsequently, the effectiveness of Atractylodes macrocephala polysaccharide (AMP) 1-1 on WIBL was investigated using a rat hindlimb suspension (HLS) model and a co-culture model of osteoblasts and RAW264.7 cell line. Results: It was found that AMP1-1 treatment improved bone microarchitecture, reduced the bone transformation rate, and enhanced bone biomechanical properties in the HLS model. In the cell co-culture system, AMP1-1 significantly inhibited osteoclastic differentiation, promoted osteoblastic differentiation, and attenuated osteoblastic apoptosis. The interaction between the nuclear factor erythroid 2-related factor 2 (Nrf2) system and antioxidant enzymes represented a key pathway mediating WIBL. Further investigation confirmed that AMP1-1 facilitated the nuclear translocation of Nrf2, up-regulated heme oxygenase-1 protein expression, and enhanced the transcription of downstream antioxidant enzymes. Consequently, it maintained bone homeostasis and protected against bone loss. Conclusions: Our findings demonstrate that AMP1-1 protects against WIBL by modulating the Nrf2 pathway and suppressing oxidative stress, offering a potential therapeutic strategy for mitigating bone loss in weightless environments.