## 3 Results
The difference between groups' average time courses did not reach statistical significance (\(p=0.56\)). A similar increase of 37% to 47% was also found in diabetic animals (\(p<0.005\) for all groups), reaching the maximum four days after setting of the wound. After day 4, vessel density as assessed via OCTA slowly decreased with again no statistically significant difference between groups (\(p=0.34\)). Figure 4: Vascular network derived from OCT angiograms. Graphics depict the OCTA data timeline acquired from the non-diabetic mouse shown in Figure 3a after post-processing. The extracted binary images were used for calculating the four vascular parameters vessel density, normalized vessel length, number of bifurcations per unit length, and vessel tortuosity. The region covered by the donut-shaped ring and the wound site were excluded during evaluation of the vascular parameters and are shown darker. Figure 5: Vascular parameters derived from OCT angiograms in (**a**,**c**,**e**,**g**) non-diabetic and (**b**,**d**,**f**,**h**) diabetic mice. (**a**,**b**) Vessel density. (**c**,**d**) Vessel length. (**e**,**f**) Number of bifurcations per vessel length. (**g**,**h**) Vessel tortuosity. The error bars represent the standard deviation. The normalized vessel length plotted in Figure 5c,d revealed a similar time course with a significant increase of 39% to 52% (\(p<0.015\) for all groups) in non-diabetic and 43% to 52% (\(p<0.01\)) in diabetic animals in the first time interval of the study period. In course of wound healing, all groups showed a slow decline of vessel length values. The average time courses of the normalized vessel length did not differ significantly between groups, neither in non-diabetic (\(p=0.46\)) nor in diabetic (\(p=0.36\)) animals. In Figure 5e,f, the number of bifurcations normalized to the vessel length for both non-diabetic and diabetic animals is plotted. A maximum number of bifurcations was detected at study day four or seven with relative increases versus baseline of 33% to 48% (\(p\leq 0.002\) for all groups). Within the study period, particularly in diabetic animals, no trend towards a decrease in bifurcation numbers was observed. There was no statistically significant difference between time courses of the control and three different treatment groups (\(p=0.34\), non-diabetic animals; \(p=0.20\), diabetic animals). Figure 5g,h show the time courses of the tortuosity parameter calculated based on the OCTA data for non-diabetic and diabetic animals, respectively. In the first time interval of the study (D1 to D4), an increase of the tortuosity by 3% to 7% in non-diabetic and 4% to 8% in diabetic animals was observed. This change was statistically significant for all treatment groups (\(p\leq 0.032\)) except the VEGF/PDGF group (\(p=0.06\)) in the non-diabetic and the chitosan hydrogel group (\(p=0.06\)) in the diabetic animals. The average time courses of the tortuosity did not show a statistically significant difference for the control and the three treatment groups, neither in non-diabetic (\(p=0.37\)) nor in diabetic (\(p=0.31\)) mice. Figure 6a,b depicts the time course of the average wound size in non-diabetic and diabetic animals and reveals a steady decline in both non-diabetic and diabetic animals and in all treatment groups and the control. At the last study day (D18), complete wound closure was observed in 11 of 24 non-diabetic and 7 of 23 diabetic animals. No statistically significant difference in the time courses of both the control and the three treatment groups was found (\(p=0.15\), non-diabetic; \(p=0.91\), diabetic). Histological specimens were obtained on the last study day 18. Example HE staining of the pinnae of one non-diabetic and one diabetic animal are depicted in Figure 7a,b, respectively, and reveal the tissue morphology with the distinct layers, that is, stratum corneum, epidermis, dermis, striated muscle fibers between the dorsal dermis and cartilage layer, and the central cartilage itself. In addition, hair follicles and sebaceous glands are visible.