Outer Bio Introduces Yuna, a System for Four-Week Experiments on Living Human Skin
Outer Bio Introduces Yuna, a System for Four-Week Experiments on Living Human Skin
On August 24, Outer Bio introduced Yuna, a laboratory system for experiments on living human skin fragments outside the body. In a related preprint, all authors are listed as company employees, equity holders, or both.
Yuna places an 8-millimeter full-thickness biopsy, a skin fragment containing the epidermis and dermis, into a porous 3D-printed insert for a laboratory plate. The upper surface of the tissue remains exposed to air, while culture medium reaches it from below through the pores. In a 2020 study, another human skin explant model maintained tissue integrity for up to nine days under the conditions described by the authors.
The Yuna authors monitored biopsies from 19 donors for up to four weeks and performed 118 replicates. After an initial period of adaptation to excision and culture, the gene activity profiles measured during weeks one through four were more similar to one another than to those of fresh skin. This distinction allows researchers to separate the biopsy's initial adaptation from changes caused by longer exposure.
In the next experiment, biopsies from four donors were treated for three weeks with the immune signaling molecules IL-17A and IL-22. The tissue maintained an inflammatory response: the activity of genes associated with inflammation and the skin barrier changed, and inflammatory proteins were released into the culture medium. Tofacitinib, a drug that blocks one immune signaling pathway, reduced some of these changes.
In a separate experiment, skin from three donors aged 58–74 years was treated for three weeks with dasatinib, either alone or in combination with quercetin. At the end of the experiment, the authors recorded lower levels of IL-6 and MMP1. SenSkin, a measure of skin cell senescence calculated from gene activity, also decreased, as did a chronic inflammation signature developed by the authors.
The four-week window provides enough time to distinguish the tissue's early adaptation from changes caused by prolonged treatment. It allows researchers to observe processes in human skin that develop over several weeks, beyond the first few days in culture.