From Cells to Self
Hannah Tam is a sixth year PhD student in the Biological and Biomedical Sciences Program at Harvard Griffin GSAS who graduates this year. A member of the Hsu Lab in the Department of Stem Cell and Regenerative Biology, Tam’s work on the regeneration of embryonic skin offers transformative potential for biomedical treatments of wounds. Tam discusses her research on organ-level regeneration, her path to her PhD, and the life-changing lessons she has received from her mentors.
Skin Deep
Regeneration is an amazing process seen across the animal kingdom—some organisms like planarians (non-parasitic flatworms) or axolotls (salamander-like amphibians) can faithfully regenerate an entire limb after an injury. But regenerating an organ is very rare for mammals. Organs are made of tissues from different lineages. Mammals can regenerate at the tissue level. (Think about your skin’s outermost layer renewing itself every few days, or your stomach lining renewing itself every few days.) But mammals have a hard time regenerating an entire organ. I utilize mammalian skin as my model system to study organ-level regeneration.
Before I joined the lab, I thought skin was just the epidermis (basically what we see on the outside), but I quickly learned that the skin contains a rich array of different cell types, including hair follicles, smooth muscle structures that allow us to get goosebumps, different kinds of nerves for us to properly sense the environment, cells that pigment our skin and hair, a host of immune cells to protect us from infection, and much more. When mammalian skin experiences an injury, epidermal cells can regenerate and cover the wound so that it’s not a gaping hole anymore, but most of the diverse cell types are lost. Importantly, the wound has an increased amount of nerves, which is why we feel pain when we get a wound, and it scars. This happens in adults and even in newborns. Wounded skin can no longer protect the organism from future environmental insults. So there is a need to not only promote tissue-level regeneration, but organ-level regeneration.
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