Faculty Bibliography

Cells suspended in bodily fluids are routinely analyzed by cytopathologists as a means of diagnosing malignancies and other diseases. The physical and morphological properties of these suspended cells are evaluated in making diagnostic decisions, which often requires manual concentration, staining, and washing procedures to extract information about intracellular architecture. The need to manually prepare slides for analysis by a cytopathologist is a labor-intensive process, which is ripe for additional automation to reduce costs but also to potentially provide more repeatable and improved accuracy in diagnoses. We have developed a microfluidic system to perform several steps in the preparation of samples for cytopathology that (i) automates colorimetric staining on-chip, and (ii) images cells in flow, as well as provides (iii) additional quantitative analyses of captured images to aid cytopathologists. A flow-through approach provides benefits by allowing staining and imaging to be performed in a continuous, integrated manner, which also overcomes previous challenges with in-suspension colorimetric staining. We envision such a tool may reduce costs and aid cytopathologists in identifying rare or characteristic cells of interest by providing isolated images along with quantitative metrics on single cells from various rotational angles, allowing efficient determination of disease etiology.

BACKGROUND:An acute infection after arthroscopic shoulder surgery is a rare but serious complication. Previous studies estimating the incidence of infections after arthroscopic surgery have been conducted, but the majority of these had either relatively small study groups or were not specific to shoulder arthroscopic surgery. PURPOSE/OBJECTIVE:To investigate the incidence of acute infections after arthroscopic shoulder surgery and compare infection rates by age group, sex, geographic region, and specific procedures. STUDY DESIGN/METHODS:Case series; Level of evidence, 4. METHODS:A retrospective review of a large insurance company database was performed for all shoulder arthroscopic surgeries performed in the United States between 2004 and 2009 that required additional surgery for infections within 30 days. The data were stratified by sex, age group, and region. Data were also stratified for specific procedures (capsulorrhaphy, treatment for superior labrum anterior-posterior tears, claviculectomy, decompression, and rotator cuff repair) and used to assess the variation in the incidence of infections across different arthroscopic shoulder procedures. Linear regression was used to determine the significance of differences in the data from year to year. χ(2) analysis was used to assess the statistical significance of variations among all groups. Poisson regression analysis with exposure was used to determine significant differences in a pairwise comparison between 2 groups. RESULTS:The total number of arthroscopic shoulder surgeries performed was 165,820, and the number of infections requiring additional surgery was 450, resulting in an overall infection rate of 0.27%. The incidence of infections varied significantly across age groups (P < .001); the infection rate was highest in the ≥60-year age group (0.36%) and lowest in the 10- to 39-year age group (0.18%). The incidence of infections also varied by region (P < .001); the incidence was highest in the South (0.37%) and lowest in the Midwest (0.11%). The incidence of infection treatments was also significantly different between different arthroscopic procedures (P < .01) and was highest for rotator cuff repair (0.29%) and lowest for capsulorrhaphy (0.16%). The incidence did not significantly vary by year or sex. CONCLUSION/CONCLUSIONS:The overall infection rate for all arthroscopic shoulder procedures was 0.27%. The incidence was highest in elderly patients, in the South, and for rotator cuff repair. The incidence was lowest in young patients, in the Midwest, and for capsulorrhaphy. In general, shoulder arthroscopic surgery in this study population had a low rate of reoperation in the acute period.

In the absence of an imaging technique that provides imagery of diseased tissue with high diagnostic accuracy and contrast, surgeons must often excise excess healthy tissue surrounding neoplasms to ensure complete removal of malignant tissues. Additional approaches that are commonly used in the detection of tumor regions include palpation and conventional ultrasound to locate the affected area. However, these techniques suffer from limitations such as minimal specificity and lack of depth penetration. Lack of specificity results in the production of unclear diseased tissue regions, and therefore fails to offer surgeons a reliable and accurate image guidance tool. The proposed work provides an alternative diagnostic modality termed ultrasound-stimulated vibro-acoustography (USVA) that aims to generate detailed images characterized by viscoelastic properties of tissues. We demonstrate selective imaging using phantom tissue samples of polyvinyl alcohol (PVA) that are altered and arranged into unique geometries of varying elastic topology. Determining the precision and sensitivity of the USVA imaging system in identifying boundary regions as well as intensity ranges associated with tissue phantom targets will provide additional important information to allow for a non-invasive tool to distinguish diseased tissues from normal tissues in an in vivo setting.

While adult heart muscle is the least regenerative of tissues, embryonic cardiomyocytes are proliferative, with embryonic stem (ES) cells providing an endless reservoir. In addition to secreted factors and cell-cell interactions, the extracellular microenvironment has been shown to play an important role in stem cell lineage specification, and understanding how scaffold elasticity influences cardiac differentiation is crucial to cardiac tissue engineering. Though previous studies have analyzed the role of the matrix elasticity on the function of differentiated cardiomyocytes, whether it affects the induction of cardiomyocytes from pluripotent stem cells is poorly understood. Here, we examined the role of matrix rigidity on the cardiac differentiation using mouse and human ES cells. Culture on polydimethylsiloxane (PDMS) substrates of varied monomer-to-crosslinker ratios revealed that rigid extracellular matrices promote a higher yield of de novo cardiomyocytes from undifferentiated ES cells. Using an genetically modified ES system that allows us to purify differentiated cardiomyocytes by drug selection, we demonstrate that rigid environments induce higher cardiac troponin T expression, beating rate of foci, and expression ratio of adult α- to fetal β- myosin heavy chain in a purified cardiac population. M-mode and mechanical interferometry image analyses demonstrate that these ES-derived cardiomyocytes display functional maturity and synchronization of beating when co-cultured with neonatal cardiomyocytes harvested from a developing embryo. Together, these data identify matrix stiffness as an independent factor that instructs not only the maturation of the already differentiated cardiomyocytes but also the induction and proliferation of cardiomyocytes from undifferentiated progenitors. Manipulation of the stiffness will help direct the production of functional cardiomyocytes en masse from stem cells for regenerative medicine purposes.

Haematopoietic cells arise from spatiotemporally restricted domains in the developing embryo. Although studies of non-mammalian animal and in vitro embryonic stem cell models suggest a close relationship among cardiac, endocardial and haematopoietic lineages, it remains unknown whether the mammalian heart tube serves as a haemogenic organ akin to the dorsal aorta. Here we examine the haemogenic activity of the developing endocardium. Mouse heart explants generate myeloid and erythroid colonies in the absence of circulation. Haemogenic activity arises from a subset of endocardial cells in the outflow cushion and atria earlier than in the aorta-gonad-mesonephros region, and is transient and definitive in nature. Interestingly, key cardiac transcription factors, Nkx2-5 and Isl1, are expressed in and required for the haemogenic population of the endocardium. Together, these data suggest that a subset of endocardial/endothelial cells serve as a de novo source for transient definitive haematopoietic progenitors.

The standard centrifuge is a laboratory instrument widely used by biologists and medical technicians for preparing cell samples. Efforts to automate the operations of concentration, cell separation, and solution exchange that a centrifuge performs in a simpler and smaller platform have had limited success. Here, we present a microfluidic chip that replicates the functions of a centrifuge without moving parts or external forces. The device operates using a purely fluid dynamic phenomenon in which cells selectively enter and are maintained in microscale vortices. Continuous and sequential operation allows enrichment of cancer cells from spiked blood samples at the mL min(-1) scale, followed by fluorescent labeling of intra- and extra-cellular antigens on the cells without the need for manual pipetting and washing steps. A versatile centrifuge-analogue may open opportunities in automated, low-cost and high-throughput sample preparation as an alternative to the standard benchtop centrifuge in standardized clinical diagnostics or resource poor settings.