White adipose tissue (WAT) is a critical organ in both health and disease. However, physiologically faithful tissue culture models of primary human WAT remain limited, at best. In this study we describe a novel WAT culture system in which primary human WAT is sandwiched between tissue-engineered sheets of adipose-derived stromal cells. This construct, called "sandwiched white adipose tissue" (SWAT), can be defined as a microphysiological system (MPS) since it is a tissue-engineered, multicellular, three-dimensional organ construct produced using human cells. We validated SWAT against the National Institutes of Health MPS standards and found that SWAT is viable in culture for 8 weeks, retains physiologic responses to exogenous signaling, secretes adipokines, and engrafts into animal models. These attributes position SWAT as a powerful tool for the study of WAT physiology, pathophysiology, personalized medicine, and pharmaceutical development.

Concurrent activation of voltage-gated sodium channels (VGSCs) and blockade of Na+ pumps causes a targeted osmotic lysis (TOL) of carcinomas that over-express the VGSCs. Unfortunately, electrical current bypasses tumors or tumor sections because of the variable resistance of the extracellular microenvironment. This study assesses pulsed magnetic fields (PMFs) as a potential source for activating VGSCs to initiate TOL in vitro and in vivo as PMFs are unaffected by nonconductive tissues. In vitro, PMFs (0–80 mT, 10 msec pulses, 15 pps for 10 min) combined with digoxin-lysed (500 nM) MDA-MB-231 breast cancer cells stimulus-dependently. Untreated, stimulation-only, and digoxin-only control cells did not lyse. MCF-10a normal breast cells were also unaffected. MDA-MB-231 cells did not lyse in a Na+-free buffer. In vivo, 30 min of PMF stimulation of MDA-MB-231 xenografts in J/Nu mice or 4T1 homografts in BALB/c mice, concurrently treated with 7 mg/kg digoxin reduced tumor size by 60–100%. Kidney, spleen, skin and muscle from these animals were unaffected. Stimulation-only and digoxin-only controls were similar to untreated tumors. BALB/C mice with 4T1 homografts survived significantly longer than mice in the three control groups. The data presented is evidence that the PMFs to activate VGSCs in TOL provide sufficient energy to lyse highly malignant cells in vitro and to reduce tumor growth of highly malignant grafts and improve host survival in vivo, thus supporting targeted osmotic lysis of cancer as a possible method for treating late-stage carcinomas without compromising noncancerous tissues.

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White adipose tissue (WAT) plays a crucial role in regulating weight and everyday health. Still, there are significant limitations to available primary culture models, all of which have failed to faithfully recapitulate the adipose microenvironment or extend WAT viability beyond two weeks. The lack of a reliable primary culture model severely impedes research in WAT metabolism and drug development. To this end we have utilized NIH's standards of a microphysiologic system to develop a novel platform for WAT primary culture called 'SWAT' (sandwiched white adipose tissue). We overcome the natural buoyancy of adipocytes by sandwiching minced WAT clusters between sheets of adipose-derived stromal cells. In this construct, WAT samples are viable over eight weeks in culture. SWAT maintains the intact ECM, cell-to-cell contacts, and physical pressures of in vivo WAT conditions; additionally, SWAT maintains a robust transcriptional profile, sensitivity to exogenous chemical signaling, and whole tissue function. SWAT represents a simple, reproducible, and effective method of primary adipose culture. Potentially, it is a broadly applicable platform for research in WAT physiology, pathophysiology, metabolism, and pharmaceutical development.

Mesothelioma is an aggressive cancer of the pleura cells of the chest cavity commonly linked to asbestos exposure. With a post‐diagnosis prognosis of between 6 and 12 months. Traditional chemotherapy increases survival time by only 11 weeks. Targeted Osmotic Lysis (TOL) is a novel cancer therapeutic that exploits cancer cells' upregulation of Voltage‐Gated Sodium Channels (VGSC) by pairing a pharmacological blocker of Na+, K+‐ATPase (sodium pumps), such as digoxin or ouabain, with electric or magnetic stimulation of VGSCs. The increase in intracellular Na+ causes an osmotic lysis of cells that over‐express VGSCs. TOL has been shown to selectively lyse highly invasive breast cancer cells, such as MDA‐MB 231, while leaving the normal tissue intact. To test the hypothesis that TOL would be an effective treatment for mesothelioma, we incubated H28 mesothelioma cells or MeT‐5A normal pleural effusion cells in 0–500 nM digoxin for 10 min, then activated the VGSCs with a 0–5 VDC electric current for 30 min. Using video microscopy, lysis was assessed by two independent observers with cytosolic extrusion as the measure. TOL effectively lysed H28 cells dose‐ and stimulus‐dependently, with a maximum cell death of 94.2% Less than 5% of cells in the Drug only, Stimulation only, and Non‐treated groups died (p<.0001). MeT‐5A cells did not lyse. Likewise, when we used a pulsed magnetic field (90 mT, 25 pps) to stimulate VGSCs, H28 cells lysed dose‐ and stimulation‐dependently, whereas control treatments and Met‐5a cells did not. Together these results are evidence that TOL causes significant cell death in mesothelioma cells compared to the normal cells. Thus, TOL may be an effective treatment for mesothelioma.Support or Funding InformationThis research was supported by a grant from Oleander Medical TechnologiesThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.