SUN-MKL1 Crosstalk Regulates Nuclear Deformation and Fast Motility of Breast Carcinoma Cells in Fibrillar ECM Microenvironment.

Aligned collagen fibers provide topography for the rapid migration of single tumor cells (streaming migration) to invade the surrounding stroma, move within tumor nests towards blood vessels to intravasate and form distant metastases. Mechanisms of tumor cell motility have been studied extensively in the 2D context, but the mechanistic understanding of rapid single tumor cell motility in the in vivo context is still lacking. Here, we show that streaming tumor cells in vivo use collagen fibers with diameters below 3 µm. Employing 1D migration assays with matching in vivo fiber dimensions, we found a dependence of tumor cell motility on 1D substrate width, with cells moving the fastest and the most persistently on the narrowest 1D fibers (700 nm-2.5 µm). Interestingly, we also observed nuclear deformation in the absence of restricting extracellular matrix pores during high speed carcinoma cell migration in 1D, similar to the nuclear deformation observed in tumor cells in vivo. Further, we found that actomyosin machinery is aligned along the 1D axis and actomyosin contractility synchronously regulates cell motility and nuclear deformation. To further investigate the link between cell speed and nuclear deformation, we focused on the Linker of Nucleoskeleton and Cytoskeleton (LINC) complex proteins and SRF-MKL1 signaling, key regulators of mechanotransduction, actomyosin contractility and actin-based cell motility. Analysis of The Cancer Genome Atlas dataset showed a dramatic decrease in the LINC complex proteins SUN1 and SUN2 in primary tumor compared to the normal tissue. Disruption of LINC complex by SUN1 + 2 KD led to multi-lobular elongated nuclei, increased tumor cell motility and concomitant increase in F-actin, without affecting Lamin proteins. Mechanistically, we found that MKL1, an effector of changes in cellular G-actin to F-actin ratio, is required for increased 1D motility seen in SUN1 + 2 KD cells. Thus, we demonstrate a previously unrecognized crosstalk between SUN proteins and MKL1 transcription factor in modulating nuclear shape and carcinoma cell motility in an in vivo relevant 1D microenvironment.

Compressed Paper as an Alternative to Corn Cob Bedding in Mouse (Mus musculus) Cages.

Bedding material is a critical component of the mouse environment and affects animal wellbeing and research integrity. Corn cob (CC) bedding has been a common bedding choice in research despite several potential negative aspects of its use. We investigated the use of compressed paper (CP) bedding as a refinement to CC bedding. CP bedding demonstrated greater total and immediate absorption, compared with CC bedding. CP-bedded cages had a reduced frequency of early cage changing prior to the Guide-recommended 2-wk interval for IVC; this reduction was proportional to room census. Intracage ammonia levels were lower in CP-bedded IVC compared with CC-bedded IVC, independent of the age, sex, and number of mice per cage. By contrast, ammonia levels were similar between CP-bedded and CC-bedded static cages. Collectively, these data support the use of CP bedding as a refinement for CC in ventilated mouse cages, in light of increased husbandry efficiency and its positive effect on the welfare of mice.

Outdate Reduction and Cost Savings with Rapid Testing for Seven-Day Platelet Storage.

Platelets for transfusion in the US are stored at room temperature which is associated with a risk of bacterial transmission and subsequent sepsis. A recent FDA Final Guidance has been issued with options to mitigate this risk while maintaining or enhancing platelet availability.Storage had been limited to five days for many years due to the risk of bacterial growth. The short shelf-life has resulted in a national outdate rate of approximately 16%. FDA has recently cleared two devices as "safety measures" the use of which now allows seven-day platelet storage in bags cleared for this option. The Platelet PGD Test (Verax Biomedical, Marlborough, MA) is one such device and the other is the bioMérieux BacT/Alert Microbial Detection System (Durham, NC). These "safety measure" options are included in the Final Guidance.In 2018 and 2019, we conducted a survey of 16 blood collection centers and 66 hospitals that use the PGD Test to extend platelet dating to seven days to ascertain how this has resulted in reduced outdating and thereby saved costs. The surveyed institutions were collectively responsible for 21-22% of the annual volume of platelet transfusions in the US.The blood collection centers reported that extension of platelet storage to seven days resulted in a mean outdate reduction of 69% (median 67%, range 23%-92%) and mean cost savings of $415,000 (median $300,000, range $150,000-$900,000). The hospitals reported that extension of platelet storage to seven days resulted in a mean outdate reduction of 74% (median 80%, range 17%-100%) and mean cost savings of $176,803 (median $150,000, range $30,000-$1,200,000). Hospitals saved 24,080 platelet doses annually and blood centers saved 18,700 doses annually. From these institutions alone, this represents a savings of more than 2% of platelet transfusions in the US.Extending platelet shelf-life to seven days with the PGD Test significantly reduced outdating of this valuable resource, increased product availability in accord with FDA Final Guidance recommendations, and saved more money than bacterial testing costs in the surveyed institutions.Results have been presented in part at the Association of Clinical Scientists Annual Meeting, Hershey, PA May 2019.