Theranostics 2022; 12(2):558-573. doi:10.7150/thno.65287 This issue

Research Paper

Non-invasive longitudinal imaging of VEGF-induced microvascular alterations in skin wounds

Yu-Hang Liu1,2,*, Lorenz M. Brunner3,*, Johannes Rebling1,2, Maya Ben-Yehuda Greenwald4, Sabine Werner4, Michael Detmar3, Daniel Razansky1,2✉

1. Institute for Biomedical Engineering and Institute of Pharmacology and Toxicology, Faculty of Medicine, University of Zurich, Zurich, Switzerland
2. Institute for Biomedical Engineering, Department of Information Technology and Electrical Engineering, ETH Zurich, Zurich, Switzerland
3. Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, Switzerland
4. Institute of Molecular Health Sciences, Department of Biology, ETH Zurich, Zurich, Switzerland
* These authors contributed equally to this work

This is an open access article distributed under the terms of the Creative Commons Attribution License ( See for full terms and conditions.
Liu YH, Brunner LM, Rebling J, Ben-Yehuda Greenwald M, Werner S, Detmar M, Razansky D. Non-invasive longitudinal imaging of VEGF-induced microvascular alterations in skin wounds. Theranostics 2022; 12(2):558-573. doi:10.7150/thno.65287. Available from

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Graphic abstract

Background: Microcirculation is essential for skin homeostasis and repair. A variety of growth factors have been identified as important regulators of wound healing. However, direct observation and longitudinal monitoring of skin remodeling in an unperturbed in vivo environment remains challenging.

Methods: We report on non-invasive longitudinal imaging of the wound healing process in transgenic mice overexpressing vascular endothelial growth factor A (VEGF-A) in keratinocytes by means of large-scale optoacoustic microscopy (LSOM). This rapid, label-free, high throughput intravital microscopy method averts the use of dorsal skin-fold chambers, allowing for fully non-invasive repeated imaging of intact wounds with capillary resolution over field-of-view spanning several centimeters.

Results: We observed VEGF-driven enhancement of dermal vascularization in ears, dorsal skin and healing wounds and quantified the hemoglobin content, fill fraction, vessel diameter and tortuosity. The in vivo findings were further corroborated by detailed side-by-side classical histological whole-mount vascular stainings and pan-endothelial CD31 immunofluorescence.

Conclusion: The new approach is suitable for supplementing or replacing the cumbersome histological procedures in a broad range of skin regeneration and tissue engineering applications.

Keywords: Angiogenesis, intravital microscopy, photoacoustic, skin wound, vascular endothelial growth factor