One of the Lunch@Lab events at the laboratory of Professor Lee Ann Applegate at the University Hospital of Lausanne (CHUV) featured making biological bandages to simulate the cell therapy that her lab has developed for treating burns and chronic wounds.
Using a biobank created from donated human fetal skin cells, her lab has developed a therapy that effectively encourages patient’s own healthy cells to regenerate and heal wounds that otherwise fester, scar, or require extensive skin grafts. Applegate and research scientist Philippe Abdel Sayed explained that the fetal cells come with advantages over undifferentiated embryonic stem cells or induced pluripotent stem cells. Namely, the fetal cells already have a “skin identity” and they are non-immunogenic. In addition, fetal skin cells, when damaged accidentally or for a biopsy in utero, regenerate quickly and leave no scarring.
To make a ‘biological bandage’, the Applegate lab uses biodegradable surgical sponges made out of collagen and elastin to first soak up a preparation of fetal cells and pink culture media. The result is a cool rectangular bandage, that feels a bit like slime, which can be placed over a wound for 1-2 days and changed out over a course of weeks. In clinical trials, the lab has shown that the bandages encourage the spontaneous healing of skin by pediatric patients with 3rd degree burns and elderly patients with chronic wounds. The fetal cells do not appear to transfer into the wounds, as evidenced by looking for the donor tissue’s Y chromosome in a female patient’s healed skin.
Applegate says it’s therefore likely that either the fetal cells are simply sending regenerative signals—including growth, adhesion, angiogenesis and migration factors—that encourage nearby healthy skin cells to proliferate and regrow healthy tissue, or the cells transfer into the wounds and send those signals, but do not survive long-term. Abdel Sayed has been working on a solution to a common problem for burn patients—infection of open wounds with multidrug resistant bacteria, most commonly Pseudomonas aeruginosa. He has developed antimicrobial polycationic dendrimers (AMPDs), which kill P. aeruginosa by interfering with the bacterium’s cell wall. These AMPDs can be added directly into the culture media that is absorbed by the bandages to ward off what can be lethal infections for burn patients.
Speaking from her office, Applegate explains that there’s enormous potential for regenerating skin from the biological bandage therapy. The fetal cells in her biobank have been used on hundreds of patients since 2008 and could keep helping patients theoretically for the next 50 years. However, the research is also not without its challenges. Because the cells are regulated like donated tissue in Switzerland, the lab must develop new ways to validate that the cells are free of newly emerging infectious agents, such as Zika virus.
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