Development of a portable reflectance confocal microscope and its application in the noninvasive in vivo evaluation of mesenchymal stem cell-promoted cutaneous wound healing

The process of wound healing is routinely evaluated by histological evaluation in the clinic, which may cause scarring and secondary injury. Reflectance confocal microscopy (RCM) represents a noninvasive, real-time imaging technique that allows in vivo evaluation of the skin. Traditional RCM was wide-probe-based, which limited its application on uneven and covered skin. In this study, we report the development of a portable reflectance confocal microscope (PRCM) in which all components were assembled in a handheld shell. Although the size and weight of the PRCM were reduced based on the use of a microelectromechanical system, the resolution was kept at 0.91 µm, and the field of view of the system was 343 μm×532 μm. When used in vivo, the PRCM was able to visualize cellular and nuclear morphology for both mouse and human skin. PRCM evaluations were then performed on wounds after topically applied mesenchymal stem cells (MSCs) or saline treatment. The PRCM allowed visualization of the formation of collagen bundles, re-epithelization from the wound edge to the wound bed, and hair follicle regeneration, which were consistent with histological evaluations. Therefore, we offer new insights into monitoring the effects of topically applied MSCs on the process of wound healing by using PRCM. This study illustrates that the newly developed PRCM represents a promising device for real-time, noninvasive monitoring of the dynamic process of wound healing, which demonstrates its potential to diagnose, monitor, or predict disease in clinical wound therapy. Graphic abstract