Digital Microfluidic Platform to Maximize Diagnostic Tests with Low Sample Volumes from Newborns and Pediatric Patients.

"Children are not tiny adults" is an adage commonly used in pediatrics to emphasize the fact that children often have different physiological responses to sickness and trauma compared to adults. However, despite widespread acceptance of this concept, diagnostic blood testing is an excellent example of clinical care that is not yet customized to the needs of children, especially newborns. Cumulative blood loss resulting from clinical testing does not typically impact critically ill adult patients, but can quickly escalate in children, leading to iatrogenic anemia and related comorbidities. Moreover, the tests prioritized for rapid, near-patient testing in adults are not always the most clinically relevant tests for children or newborns. This report describes the development of a digital microfluidic testing platform and associated clinical assays purposely curated to address current shortcomings in pediatric laboratory testing by using microliter volumes (<50 µL) of samples. The automated platform consists of a small instrument and single-use cartridges, which contain all reagents necessary to prepare the sample and perform the assay. Electrowetting technology is used to precisely manipulate nanoliter-sized droplets of samples and reagents inside the cartridge. To date, we have automated three disparate types of assays (biochemical assays, immunoassays, and molecular assays) on the platform and have developed over two dozen unique tests, each with important clinical application to newborns and pediatric patients. Cell lysis, plasma preparation, magnetic bead washing, thermocycling, incubation, and many other essential functions were all performed on the cartridge without any user intervention. The resulting assays demonstrate performance comparable to standard clinical laboratory assays and are economical due to the reduced hands-on effort required for each assay and lower overall reagent consumption. These capabilities allow a wide range of assays to be run simultaneously on the same cartridge using significantly reduced sample volumes with results in minutes.

The balance of cell surface and soluble type III TGF-ß receptor regulates BMP signaling in normal and cancerous mammary epithelial cells.

Bone morphogenetic proteins (BMPs) are members of the TGF-ß superfamily that are over-expressed in breast cancer, with context dependent effects on breast cancer pathogenesis. The type III TGF-ß receptor (TßRIII) mediates BMP signaling. While TßRIII expression is lost during breast cancer progression, the role of TßRIII in regulating BMP signaling in normal mammary epithelium and breast cancer cells has not been examined. Restoring TßRIII expression in a 4T1 murine syngeneic model of breast cancer suppressed Smad1/5/8 phosphorylation and inhibited the expression of the BMP transcriptional targets, Id1 and Smad6, in vivo. Similarly, restoring TßRIII expression in human breast cancer cell lines or treatment with sTßRIII inhibited BMP-induced Smad1/5/8 phosphorylation and BMP-stimulated migration and invasion. In normal mammary epithelial cells, shRNA-mediated silencing of TßRIII, TßRIII over-expression, or treatment with sTßRIII inhibited BMP-mediated phosphorylation of Smad1/5/8 and BMP induced migration. Inhibition of TßRIII shedding through treatment with TAPI-2 or expression of a non-shedding TßRIII mutant rescued TßRIII mediated inhibition of BMP induced Smad1/5/8 phosphorylation and BMP induced migration and/or invasion in both in normal mammary epithelial cells and breast cancer cells. Conversely, expression of a TßRIII mutant, which exhibited increased shedding, significantly reduced BMP-mediated Smad1/5/8 phosphorylation, migration, and invasion. These data demonstrate that TßRIII regulates BMP-mediated signaling and biological effects, primarily through the ligand sequestration effects of sTßRIII in normal and cancerous mammary epithelial cells and suggest that the ratio of membrane bound versus sTßRIII plays an important role in mediating these effects.

Ectodomain shedding of TßRIII is required for TßRIII-mediated suppression of TGF-ß signaling and breast cancer migration and invasion.

The type III transforming growth factor ß (TGF-ß) receptor (TßRIII), also known as betaglycan, is the most abundantly expressed TGF-ß receptor. TßRIII suppresses breast cancer progression by inhibiting migration, invasion, metastasis, and angiogenesis. TßRIII binds TGF-ß ligands, with membrane-bound TßRIII presenting ligand to enhance TGF-ß signaling. However, TßRIII can also undergo ectodomain shedding, releasing soluble TßRIII, which binds and sequesters ligand to inhibit downstream signaling. To investigate the relative contributions of soluble and membrane-bound TßRIII on TGF-ß signaling and breast cancer biology, we defined TßRIII mutants with impaired (ΔShed-TßRIII) or enhanced ectodomain shedding (SS-TßRIII). Inhibiting ectodomain shedding of TßRIII increased TGF-ß responsiveness and abrogated TßRIII's ability to inhibit breast cancer cell migration and invasion. Conversely, expressing SS-TßRIII, which increased soluble TßRIII production, decreased TGF-ß signaling and increased TßRIII-mediated inhibition of breast cancer cell migration and invasion. Of importance, SS-TßRIII-mediated increases in soluble TßRIII production also reduced breast cancer metastasis in vivo. Taken together, these studies suggest that the ratio of soluble TßRIII to membrane-bound TßRIII is an important determinant for regulation of TßRIII- and TGF-ß-mediated signaling and biology.

Targeting interleukin 6 signaling suppresses glioma stem cell survival and tumor growth.

Glioblastomas are the most common and most lethal primary brain tumor. Recent studies implicate an important role for a restricted population of neoplastic cells (glioma stem cells (GSCs)) in glioma maintenance and recurrence. We now demonstrate that GSCs preferentially express two interleukin 6 (IL6) receptors: IL6 receptor alpha (IL6R alpha) and glycoprotein 130 (gp130). Targeting IL6R alpha or IL6 ligand expression in GSCs with the use of short hairpin RNAs (shRNAs) significantly reduces growth and neurosphere formation capacity while increasing apoptosis. Perturbation of IL6 signaling in GSCs attenuates signal transducers and activators of transcription three (STAT3) activation, and small molecule inhibitors of STAT3 potently induce GSC apoptosis. These data indicate that STAT3 is a downstream mediator of prosurvival IL6 signals in GSCs. Targeting of IL6R alpha or IL6 expression in GSCs increases the survival of mice bearing intracranial human glioma xenografts. IL6 is clinically significant because elevated IL6 ligand and receptor expression are associated with poor glioma patient survival. The potential utility of anti-IL6 therapies is demonstrated by decreased growth of subcutaneous human GSC-derived xenografts treated with IL6 antibody. Together, our data indicate that IL6 signaling contributes to glioma malignancy through the promotion of GSC growth and survival, and that targeting IL6 may offer benefit for glioma patients.