## 1 Introduction
Animal models are essential for investigating both the physiological and pathological mechanisms involved in tissue repair after wounding [40; 41]. Here, due to their relatively low cost and their simple handling, mice represent the most widely used species for preclinical wound healing studies [42; 43]. Despite various molecular [44; 45] and immunological [46; 47] differences between humans and mice, the healing of skin woundsin the two species is similar considering the aforementioned four overlapping phases of wound healing [48; 49]. In addition, human and murine skin possess the same layers of cells in the dermis and epidermis; they differ, however, in terms of thickness and number of cell layers [47]. The relatively thin structure of the mouse ear pinna skin makes this location ideally suited for an investigation with optical imaging methods, which is why the mouse pinna model has been employed for in vivo assessment of normal [13; 50; 51] and impaired [52] wound healing in a longitudinal manner. OCTA has also been used to monitor wound healing in humans. For example, [PERSON] et al. applied OCTA to monitor the vasculature after a burn injury [53], [PERSON] et al. took repeated OCT/OCTA measurements after skin injury caused by a drop of molten plastic [54], and [PERSON] et al. investigated leg ulcers in 11 patients with OCT/OCTA [55]. Although the aforementioned studies demonstrated the applicability of OCTA for monitoring of wound healing in humans, for studies that compare multiple treatments of artificially set wounds, animal studies are preferable. Topical applications of different agents are utilized to enhance angiogenesis and healing outcome. Vascular endothelial growth factor (VEGF), in addition to attracting leukocytes to the wound site, plays an essential role in vascular and lymphatic growth and was shown to significantly improve the healing outcome in diabetic mouse dorsal wound models [56; 57]. Platelet derived growth factor (PDGF) was reported to increase the rate of cellular infiltration and capillary ingrowth into dorsal wounds of diabetic mice [58]. Beside these well-studied pro-angiogenic growth factors, the effect of different biological polymers on the wound healing outcome has been investigated [59]. For example, chitosan, a positively charged linear polysaccharide composed of randomly distributed \(\beta\)-(1\(\rightarrow\)4)-linked D-glucosamine and N-acetyl-D-glucosamine was reported to enhance the function of inflammatory cells and promotes granulation during the proliferative stage of wound healing [60]. In addition, its hemostatic and antimicrobial activities [61] together with its excellent biocompatibility make it well suited for the use in wound healing dressings [59]. The current exploratory study aimed to investigate whether optical imaging via OCT/OCTA can be employed for the evaluation of dermal wound healing in diabetic db/db and healthy C57 BL/6 mice receiving different proangiogenic treatments. Longitudinal assessment of angiogenesis and vascular remodeling during wound healing was performed using OCTA, with the goal of evaluating quantitative OCTA-based parameters and their applicability for objective assessment of the healing status. The primary objective was to investigate whether OCTA imaging allows for the detection of differences in the adaptational changes of the microvasculature due to the treatment.