Intravital imaging of hair follicle regeneration in the mouse

Light-Patterned RNA Interference of 3D-Cultured Human Embryonic Stem Cells

A new method of spatially controlled gene regulation in 3D-cultured human embryonic stem cells is developed using hollow gold nanoshells (HGNs) and near-infrared (NIR) light. Targeted cell(s) are discriminated from neighboring cell(s) by focusing NIR light emitted from a two-photon microscope. Irradiation of cells that have internalized HGNs releases surface attached siRNAs and leads to concomitant gene downregulation.

Preclinical Advances with Multiphoton Microscopy in Live Imaging of Skin Cancers

Conventional, static analyses have historically been the bedrock and tool of choice for the study of skin cancers. Over the past several years, in vivo imaging of tumors using multiphoton microscopy has emerged as a powerful preclinical tool for revealing detailed cellular behaviors from the earliest moments of tumor development to the final steps of metastasis. Multiphoton microscopy allows for deep tissue penetration with relatively minor phototoxicity, rendering it an effective tool for the long-term observation of tumor evolution. This review highlights some of the recent preclinical insights gained using multiphoton microscopy and suggests future advances that could enhance its power in revealing the mysteries of skin tumor biology.

The thrill of scientific discovery and leadership with my group

My group and I feel tremendously honored to be recognized with the 2016 Early Career Life Scientist Award from the American Society for Cell Biology. In this essay I share the scientific questions that my lab has been excitedly pursuing since starting in August 2009 and the leadership behaviors we have adopted that enable our collective scientific productivity.

Spatiotemporal coordination of stem cell commitment during epidermal homeostasis

Adult tissues replace lost cells via pools of stem cells. However, the mechanisms of cell self-renewal, commitment, and functional integration into the tissue remain unsolved. Using imaging techniques in live mice, we captured the lifetime of individual cells in the ear and paw epidermis. Our data suggest that epidermal stem cells have equal potential to either divide or directly differentiate. Tracking stem cells over multiple generations reveals that cell behavior is not coordinated between generations. However, sibling cell fate and lifetimes are coupled. We did not observe regulated asymmetric cell divisions. Lastly, we demonstrated that differentiating stem cells integrate into preexisting ordered spatial units of the epidermis. This study elucidates how a tissue is maintained by both temporal and spatial coordination of stem cell behaviors.

Epithelial Skin Biology: Three Decades of Developmental Biology, a Hundred Questions Answered and a Thousand New Ones to Address

The mammalian skin epidermis and its hair and sweat gland appendages provide a protective barrier that retains essential body fluids, guards against invasion by harmful microbes, and regulates body temperature through the ability to sweat. At the interface between the external environment and the body, skin is constantly subjected to physical trauma and must also be primed to repair wounds in response to injury. In adults, the skin maintains epidermal homeostasis, hair regeneration, and wound repair through the use of its stem cells. This essay focuses on when stem cells become established during skin development and where these cells reside in adult epithelial tissues of the skin. I explore how skin stem cells maintain tissue homeostasis and repair wounds and how they regulate the delicate balance between proliferation and differentiation. Finally, I tackle the relation between skin cancer and mutations that perturb the regulation of stem cells.