A novel cell culture system that monitors keratinocytes during negative-pressure wound therapy may be more easily incorporated into existing laboratories.
Negative-pressure wound therapy (NPWT) is a proven approach to wound care that has been enlisted in a range of therapeutic scenarios including difficult-to-treat wounds such as burns. Its efficacy in clinical practice is widely known, but basic in vitro studies using cells are lacking, and the mechanism underlying NPWT effects remains largely unknown.
This is due primarily to the scarcity of relevant in vitro studies, according to findings published in Skin Research & Technology. To address this gap, Toshifumi Yamashiro, MD, and colleagues developed an in vitro cell culture system that provided real-time monitoring of cells during NPWT. The researchers used human keratinocytes, PSVK-1, that were divided into ambient pressure (AP), continuous negative-pressure (NPc), and intermittent negative-pressure (NPi) groups and cultured for 24 hours. Measurements included pressure inside the device, medium evaporation rate, and residual wound area and were compared across the groups.
Pressure inside the device remained consistent at nearly the same value as set by the researchers throughout all groups, according to the study results. The study group observed a significantly higher evaporation rate in the NPi group compared with the other two groups, although this had a “negligible” impact on cell culture. The residual wound area remaining at 9 hours—which Dr. Yamashiro and colleagues examined using a scratch assay—was significantly smaller in the NPc and NPi groups compared with the AP group (Figure).
Dr. Yamashiro discussed this research, and its implications for wound care, with Physician’s Weekly.
PW: Why is real-time monitoring of cells during NPWT important to study?
Dr. Yamashiro: It has been 25 years since NPWT was introduced into clinical practice. It is so well known to surgeons and wound care practitioners that it is considered one of the paradigm shifts of the 21st century in the field of wound care. However, when we investigated it, we found that the evidence was surprisingly inadequate. We decided to undertake this study because we thought it could provide evidence for more effective use of this relatively new treatment.
PW: What are the most important findings to emphasize?
Dr. Yamashiro: Our report provides only one avenue for in vitro studies of NPWT, but we believe that it is more easily incorporated into laboratories everywhere than previous reports. NPWT was developed on a commercial basis and there may have been an insufficient opportunity to review the evidence. For example, the perspective on the efficacy of intermittent negative pressure, which re-emerged around 2010, was already noted in the first report on NPWT in 1997. We believe that the time may have come to re-examine this treatment from a scientific perspective.
PW: How will the treatment of infected wounds be impacted by the results?
Dr. Yamashiro: The hottest topic in NPWT today is undoubtedly the prevention of surgical site infections with incisional negative pressure wound therapy (iNPWT). As noted elsewhere, skin disorders in iNPWT are one of the most common problems encountered in clinical practice, and clinicians manage the issue with our own experience. Our study focusing on keratinocytes is an important step forward in providing scientific evidence.
PW: What would you like future research to focus on?
Dr. Yamashiro: Because NPWT has traditionally been used for open wounds, there is a relative abundance of studies focusing on cells of the granulation tissue, but the effects on other tissues have not been fully investigated. This includes epithelial cells, which we have reported, as well as nerve, bone, and, surprisingly, tumor cells. There is still a great deal to explore.
