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Abstract Astronauts experience significant and rapid bone loss as a result of an extended stay in space, making the International Space Station (ISS) the perfect laboratory for studying osteoporosis due to the accelerated nature of bone loss on the ISS. This prompts the question, how does the lack of load due to zero-gravity propagate to bone-forming cells, human fetal osteoblasts (hFOBs), altering their maturation to mineralization? Here, we aim to study the mechanotransduction mechanisms by which bone loss occurs in microgravity. Two automated experiments, microfluidic chips capable of measuring single-cell mechanics via aspiration and cell spheroids incubated in pressure-controlled chambers, were each integrated into a CubeLab deployed to the ISS National Laboratory. For the first experiment, we report protrusion measurements of aspirated cells after exposure to microgravity at the ISS and compare these results to ground control conducted inside the CubeLab. We found slightly elongated protrusions for space samples compared to ground samples indicating softening of hFOB cells in microgravity. In the second experiment, we encapsulated osteoblast spheroids in collagen gel and incubated the samples in pressure-controlled chambers. We found that microgravity significantly reduced filamentous actin levels in the hFOB spheroids. When subjected to pressure, the spheroids exhibited increased pSMAD1/5/9 expression, regardless of the microgravity condition. Moreover, microgravity reduced YAP expression, while pressure increased YAP levels, thus restoring YAP expression for spheroids in microgravity. Our study provides insights into the influence of microgravity on the mechanical properties of bone cells and the impact of compressive pressure on cell signaling in space.

Abstract Background Uncontrolled growth in solid breast cancer generates mechanical compression that may drive the cancer cells into a more invasive phenotype, but little is known about how such compression affects the key events and corresponding regulatory mechanisms associated with invasion of breast cancer cells including cellular behaviors and matrix degradation. Results Here we show that compression enhanced invasion and matrix degradation of breast cancer cells. We also identified Piezo1 as the putative mechanosensitive cellular component that transmitted compression to not only enhance the invasive phenotype, but also induce calcium influx and downstream Src signaling. Furthermore, we demonstrated that Piezo1 was mainly localized in caveolae, and both Piezo1 expression and compression-enhanced invasive phenotype of the breast cancer cells were reduced when caveolar integrity was compromised by either knocking down caveolin1 expression or depleting cholesterol content. Conclusions Taken together, our data indicate that mechanical compression activates Piezo1 channels to mediate enhanced breast cancer cell invasion, which involves both cellular events and matrix degradation. This may be a critical mechanotransduction pathway during breast cancer metastasis, and thus potentially a novel therapeutic target for the disease.

Cellular unjamming is the collective fluidization of cell motion and has been linked to many biological processes, including development, wound repair, and tumor growth. In tumor growth, the uncontrolled proliferation of cancer cells in a confined space generates mechanical compressive stress. However, because multiple cellular and molecular mechanisms may be operating simultaneously, the role of compressive stress in unjamming transitions during cancer progression remains unknown. Here, we investigate which mechanism dominates in a dense, mechanically stressed monolayer. We find that long-term mechanical compression triggers cell arrest in benign epithelial cells and enhances cancer cell migration in transitions correlated with cell shape, leading us to examine the contributions of cell–cell adhesion and substrate traction in unjamming transitions. We show that cadherin-mediated cell–cell adhesion regulates differential cellular responses to compressive stress and is an important driver of unjamming in stressed monolayers. Importantly, compressive stress does not induce the epithelial–mesenchymal transition in unjammed cells. Furthermore, traction force microscopy reveals the attenuation of traction stresses in compressed cells within the bulk monolayer regardless of cell type and motility. As traction within the bulk monolayer decreases with compressive pressure, cancer cells at the leading edge of the cell layer exhibit sustained traction under compression. Together, strengthened intercellular adhesion and attenuation of traction forces within the bulk cell sheet under compression lead to fluidization of the cell layer and may impact collective cell motion in tumor development and breast cancer progression.

BackgroundYouth with anxiety and obsessive–compulsive disorder (OCD) rarely access exposure therapy, an evidence-based treatment. Known barriers include transportation, waitlists, and provider availability. Efforts to improve access to exposure require an understanding of the process that families take to find therapists, yet no prior studies have examined parents’ perspectives of the steps involved.MethodsParents of children who have received exposure therapy for anxiety and/or OCD (N = 23) were recruited from a hospital-based specialty anxiety clinic where the majority of their children previously received exposure. Recruitment was ongoing until thematic saturation was reached. Parents completed questionnaires and attended an online focus group during which they were asked to describe each step they took—from recognizing their child needed treatment to beginning exposure. A process map was created and shown in real-time, edited for clarity, and emailed to parents for member checking. Authors analyzed process maps to identify common themes.ResultsSeveral themes emerged, as visually represented in a final process map. Participants identified a “search-outreach” loop, in which they repeated the cycle of looking for therapists, contacting them, and being unable to schedule an appointment due to factors such as cost, waitlists, and travel time. Parents often did not know about exposure and reported feeling guilty about their lack of knowledge and inability to find a suitable provider. Parents reported frustration that medical providers did not often know about exposure and sometimes dismissed parents’ concerns. Participants emphasized the difficulty of navigating the mental health system; many reported that it took years to find an exposure therapist, and that the search was sometimes stalled due to fluctuating symptoms.ConclusionA common thread among identified barriers was the amount of burden placed on parents to find treatment with limited support, and the resultant feelings of isolation and guilt. Findings point to several directions for future research, such as the development of parent support groups for navigating the mental health system; enhancing coordination of care between medical and mental health providers; and streamlining referral processes.

The preparation of new, enantiomerically pure, α-amino acids from easily available starting materials is an ongoing challenge in synthetic organic chemistry. Here, we describe the syntheses and crystal structures of three chiral oxazolidinone derivatives prepared from L-alanine and pivalaldehyde to form a Schiff base intermediate and then reaction with the appropriate acid chloride to form the heterocycle. In each compound, the methyl and tert-butyl substituents lie to the same side of the molecule: these homochiral ‘cis’ structures were separated from their trans diastereomers by fractional crystallisation. The five-membered rings in these structures adopt various conformations including envelopes with either a C or O atom as the flap and twisted about a C–O bond. The extended structures of two of these compounds feature C(6) chains of molecules linked by C–H···O hydrogen bonds: one of these has a notably short H···O separation of 2.24 (3) Å.