The inherent heterogeneity in cell populations has become of great interest and importance as analytical techniques have improved over the past decades. With the advent of personalized medicine, understanding the impact of this heterogeneity has become an important challenge for the research community. Many different microfluidic approaches with varying levels of throughput and resolution exist to study single cell activity. In this review, we take a broad view of the recent microfluidic developments in single cell analysis based on microwell, microchamber, and droplet platforms. We cover physical, chemical, and molecular biology approaches for cellular and molecular analysis including newly emerging genome-wide analysis.

Epigenetic mechanisms such as histone modifications play critical roles in adaptive tuning of chromatin structures. Profiling various histone modifications at the genome scale using tissues from animal and human samples is an important step for functional studies of epigenomes and epigenomics-based precision medicine. Because the profile of a histone mark is highly specific to a cell type, cell isolation from tissues is often necessary to generate a homogeneous cell population and such operation tends to yield a low number of cells. In addition, high-throughput processing is often desirable due to the multiplexity of histone marks of interest and the large quantity of samples in a hospital setting. In this protocol, we describe detailed instructions on device fabrication, setup, and operation of microfluidic oscillatory washing-based chromatin immunoprecipitation followed by sequencing (MOWChIP-seq) for profiling histone modifications using as few as 100 cells per assay with a throughput as high as 8 assays in a run. MOWChIP-seq operation involves flowing of chromatin fragments through a packed bed of antibody-coated beads followed by vigorous microfluidic oscillatory washing. Our process is semi-automated for reduced labor and improved reproducibility. Using one 8-unit device, it takes 2 d to produce 8 sequencing libraries from chromatin samples. The technology is scalable. We used the protocol to study a number of histone modifications in various types of mouse and human tissues. The protocol can be conducted by a user who is familiar with molecular biology procedures and has basic engineering skills.

Intravenous (IV) infiltrations are problematic complications associated with hospitalization. Treatment methods vary greatly on the basis of physician judgment and institutional protocol, and uniform methods for effective prevention and economical treatment of IV infiltrations are necessary. Common in neonatal and infant patients, infiltration is frequently associated with cosmetic and functional complications. Medicolegal issues for physicians and institutions also accompany many cases of infiltration. This article discusses the pathophysiology of IV infiltrations. It also presents a new scale for IV infiltrations that more accurately reflects issues common to neonatal and pediatric patients and describes a novel, noninvasive treatment. A quantitative study of the decrease in morbidity after implementing this protocol will be conducted pending institutional approval.