Beware of the toilet: The risk for a deep tissue injury during toilet sitting.

A pressure injury (PrI) compromises quality of life and can be life-threatening. The fundamental cause of PrIs is sustained deformations in weight-bearing soft tissues, e.g., during prolonged sitting on inadequate surfaces such as a toilet seat. In nursing homes and geriatric facilities, patients need assistance using the restroom, and patients being left on the toilet for tens-of-minutes is a real-world scenario, unfortunately. Nevertheless, there are no published studies regarding sustained tissue loads during toilet sitting and their effects on tissue physiology. Here, the biomechanical and microcirculatory responses of the buttock tissues to toilet sitting were investigated using finite element modeling and cutaneous hemodynamic measurements, to explore the potential etiology of PrIs occurring on the toilet. We found that prolonged sitting on toilet seats involves a potential risk for PrI development, the extent of which is affected by the seat design. Additionally, we found that specialized toilet seat cushions are able to reduce this risk, by lowering instantaneous tissue exposures to internal stresses (by up to 88%) and maintaining reduced interface pressures. Furthermore, hemodynamic variables were altered during the toilet sitting; in particular, tcPO2 was decreased by 49% ± 7% (44 ± 2[mmHg] to 22 ± 4[mmHg]) during sitting. The current study confirms that investing in expensive PrI prevention (PIP) products is likely to be ineffective for an immobilized patient who is left to sit on a bare toilet seat for long times. This argument highlights the need for a holistic-care approach, employing PIP devices that span across the entire environment where bodyweight forces apply to tissues.

Pluripotent stem cells as a cellular model for skin: relevance for physiopathology, cell/gene therapy and drug screening.

The skin represents the largest tissue in the human body. Its external part, the epidermis, accomplishes vital functions such as barrier protection, thermoregulation and immune function. The mammalian skin epidermis has been for decades the paradigm for studying the molecular events that occur in tissue homeostasis and repair. Many genes and signaling pathways have been identified by the use of manipulated transgenic and KO mice. However, despite numerous elegant transgenic mice experiments, absence of an appropriate in vitro model system has hampered the molecular study of the early events responsible for epidermal and dermal commitments, stages at which congenital genetic alterations are responsible for hundreds of rare skin diseases. For most of them, etiology and treatment are still missing. Here we review the last decade of studies aimed at designing cellular models from pluripotent stem cells (PSC) that recapitulate in vitro the main molecular steps of skin formation. As described below, PSC-based models are powerful tools to (i) clarify early molecular events that occur during epithelial/mesenchymal interactions, (ii) produce in large amount skin cells that could become an alternative for cell/gene therapies and (iii) screen for therapeutic compounds to treat genodermatoses.