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Siddiqi, U.

Publications and source records attributed to Siddiqi, U..

2 recordsLinked to original sources

Tissue Engineering Applications for Novel Integrated and Mobile Perfusion System

Perfusion offers unique benefits to tissue-engineered systems, enhancing oxygen and nutrient transport which improves tissue formation and growth. In this study, we present a novel and integrated portable perfusion system, termed the FluidON. Weighing <10 lbs, the system can maintain continuous flow in a standard incubation environment (37{degrees}C, 5% CO2), effectively functioning as a portable perfusion and culture chamber. To test the systems perfusion parameters, we measured the volumetric flow rate across a range of pressures and found that the system could achieve flow as low as 0.40{+/-} 0.19uL/s, which is similar to in vivo interstitial flow. Computational fluid dynamics revealed uniform flow distribution, laminar flow, and gentle circulation, helping ensure even fluid and nutrient distribution. To study the biocompatibility of the system, bioengineered tissue patches were created and perfused. Viability was assessed through flow cytometry. The system does not adversely affect cell health as the viability of perfused samples was found to be 40.99{+/-}6.22% alive after 24 hours (n=4), while that of the static control was 38.56{+/-}4.22% alive (n=4). To determine the effects of perfusion on spheroid spatial arrangement, perfused tissue patches were analyzed with light microscopy. It was discovered that perfusion promoted spheroid aggregation and cohesion, causing the distance from one spheroid to its nearest neighbor to decrease after 24 hours of perfusion. Perfusion was also found to improve the strength of hydrogels as the average hole area, caused by hydrolytic enzymes that degrade the hydrogel matrix, was smaller in perfused conditions compared to the control. Complemented by its ability to provide mobile perfusion and incubation, this novel integrated portable perfusion system holds promise for promoting tissue maturation, elevating tissue bioengineering studies.

bioengineering↗

Inhibition of EGFR/ErbB does not protect against C. difficile toxin B

Clostridioides difficile is a common cause of diarrhea and mortality, especially in immunosuppressed and hospitalized patients. C. difficile is a toxin-mediated disease, but the host cell receptors for C. difficile toxin B (TcdB) have only recently been revealed. Emerging data suggest TcdB interacts with receptor tyrosine kinases during infection. In particular, TcdB can elicit Epidermal Growth Factor Receptor (EGFR) transactivation in human colonic epithelial cells. The mechanisms for this function are not well understood, and the involvement of other receptors in the EGFR family of Erythroblastic Leukemia Viral Oncogene Homolog (ErbB) receptors remains unclear. Furthermore, in an siRNA-knockdown screen for protective genes involved with TcdB toxin pathogenesis, we show ErbB2 and ErbB3 loss resulted in increased cell viability. We hypothesize TcdB induces the transactivation of EGFR and/or ErbB receptors as a component of its cell-killing mechanism. Here, we show in vivo intrarectal instillation of TcdB in mice leads to phosphorylation of ErbB2 and ErbB3. However, immunohistochemical staining for phosphorylated ErbB2 and ErbB3 indicated no discernible difference between control and TcdB-treated mice for epithelial phospho-ErbB2 and phospho-ErbB3. Human colon cancer cell lines (HT29, Caco-2) exposed to TcdB were not protected by pre-treatment with lapatinib, an EGFR/ErbB2 inhibitor. Similarly, lapatinib pre-treatment failed to protect normal human colonoids from TcdB-induced cell death. Neutralizing antibodies against mouse EGFR failed to protect mice from TcdB intrarectal instillation as measured by edema, inflammatory infiltration, and epithelial injury. Our findings suggest TcdB-induced colonocyte cell death does not require EGFR/ErbB receptor tyrosine kinase activation.

microbiology↗