Wounds heal more slowly in space

Wounds heal more slowly in space, with the tissue repair process differing significantly from what occurs on Earth. This is the key finding of the remarkable "Suture in Space" experiment, conducted by an international team to investigate the effects of microgravity on the healing process. Sutured wound models, developed from biological tissue samples, were sent to the International Space Station (ISS) two years ago, where they remained for nine days before being returned to Earth for analysis. The results of the project were presented on Tuesday, 15 October, in Milan during the International Astronautical Congress, one of the world’s most significant events for space exploration and services.

The study, spanning seven years from conception to results, was led by Monica Monici of the Joint ASAcampus Laboratory for the Biology of Physical Stresses. This laboratory was established by the Department of Experimental and Clinical Biomedical Sciences at the University of Florence in collaboration with the Research Division of ASA (Arcugnano, Vicenza), a leading company in laser systems for medical applications and devices for magnetotherapy. The research, selected by the European Space Agency (ESA) and funded by the Italian Space Agency (ASI), also involved the Careggi University Hospital and several Italian and European universities.

In the initial phase of the project, the Joint Laboratory developed sutured wound models using ex vivo cultures of human tissues, including skin and blood vessels. This was made possible by a novel culturing technique that preserved tissue viability for over four weeks. This stage was conducted in collaboration with surgeons from the Careggi University Hospital and the Department of Experimental and Clinical Medicine at the University of Florence.

In November 2022, the biological samples were launched aboard SpX-26 (Cargo Dragon 2) from the Kennedy Space Center (KSC) in Cape Canaveral, Florida, to the ISS. The researchers’ mission to KSC to prepare the samples for launch was sponsored by Revée srl (Turin), a leading company in post-operative medical devices used by patients following plastic, reconstructive, and aesthetic surgery. Once aboard the ISS, the biological samples were placed in an incubator set to 32 degrees Celsius. After four days, half of the samples were frozen at minus 80 degrees Celsius, while the remaining samples underwent the same treatment after nine days. The hardware enabling the automated experiment aboard the ISS was developed by Kayser Italia (Livorno) and OHB (Bremen, Germany).

In the second phase of the project, the samples returned to Earth were analysed in collaboration with other project partners, both national (the Universities of Milan, Siena, and Molise) and international (the Universities of Amsterdam, Aarhus, and Lucerne).

“All biological samples,” explains Monica Monici, “were divided and shared among the various Italian and European research groups involved in the project. Each group conducted specific analyses on the tissue portions, and the resulting data were consolidated to provide an overarching view of the findings.”

“The initial results of the experiment confirm what preliminary studies had already suggested: wound healing in space is delayed and altered compared to on Earth,” Monici states. “One of the primary objectives of the project was to gather insights into the tissue remodelling phase during the wound healing process. The findings demonstrate significant changes in the quantitative relationships between different components of the extracellular matrix in space, which also affect its mechanical properties. The extracellular matrix is the non-cellular component of tissues; it not only provides structural support to cells but also transmits biochemical and mechanical signals, thus playing crucial roles. Furthermore, we observed alterations in the activation of cellular populations involved in the wound healing process, such as fibroblasts and keratinocytes.”