## 4 Discussion
Future experiments based on these data can form the basis for the definition of OCTA biomarkers applicable for an objective assessment of wound healing progression and for the planning of new studies investigating pharmacological interventions in cutaneous tissue repair. Another aspect that could be considered a limitation of the current study is analysis of vascular network based on two-dimensional en-face projections of the OCTA data instead of the original three-dimensional data sets. The vascular tree of the mouse ear pinna is composed of a descending order of arterioles and venules [83; 84; 85], where the lower orders run deep in the dermis layer on both sides of the cartilage, while the higher order vessels and capillary loops occupy the superficial dermis and deep epidermis. In the current study that aimed to investigate the applicability of OCTA for tracking dermal wound healing during treatment with proangiogenic substances, a full thickness wound, extending down to the cartilage layer and removing all skin layers including the enclosed vessels, was set. Since this standardized wound was applied in all animals of all treatment groups, no bias on the study results due to the two-dimensional analysis is to be expected. However, the analysis of the three-dimensional data set can provide a more detailed insight into the angioarchitecture of the microcirculation both in preclinical research and also for the clinical assessment of wounds or lesions of the skin [38]. Regarding the clinical applicability of OCTA for dermatological applications, one must consider the previously mentioned penetration depth of a few millimeters into tissue. This allows assessment of the superficial capillary loops and the underlying capillary and vessel beds. The combination with PA imaging in a multimodal imaging system, however, can provide a full representation of the skin vasculature [86]. Here, the PA channel yields the visualization of vessels with diameters in the range of \(\sim\)100 m and larger down to a depth of 5-10 mm while OCTA facilitates imaging of the superficial perfusion [87; 88]. Recently, such a multimodal system has been employed for imaging and quantitative assessment of the dermal vasculature in different dermatological conditions [89]. In conclusion, we demonstrated the applicability of dermal OCTA for in vivo tracking of the dynamic changes in the vascular network after application of an excisional wound model in the mouse pinna. The high resolution of the imaging system provided an insight into adaptational changes of the microvasculature during the overlapping wound healing phases in both non-diabetic and diabetic animals. The obtained data reflected well the processes after injury during hemostatic, inflammatory, proliferative, and remodeling phases. Our results indicate that OCTA could serve as a valuable preclinical research tool for evaluating the impaired adaptational mechanisms in vascular remodeling leading to the formation of chronic wounds and for monitoring the outcome of new pharmacologic treatment strategies facilitating or enhancing wound repair after injury. The following are available online at [[https://www.mdpi.com/2076-341](https://www.mdpi.com/2076-341)]([https://www.mdpi.com/2076-341](https://www.mdpi.com/2076-341)) 7/11/5/2447/s1. Conceptualization, C.H., L.S. and R.M.W. ; methodology, K.S. and R.M.W. ; software, M.P. and H.S. ; validation, M.P., K.S. and R.M.W. ; formal analysis, M.P., K.S., H.S. and R.M.W. ; investigation, M.P., K.S., B.J.S., S.P. and H.S. ; resources, K.S. and C.H. ; data curation, M.P. and R.M.W., writing--original draft preparation, M.P., K.S. and R.M.W. ; writing--review and editing, C.H., M.M., G.G. and L.S. ; visualization, M.P. and R.M.W. ; supervision, L.S. and R.M.W. ; funding acquisition, L.S. and R.M.W. All authors have read and agreed to the published version of the manuscript.