Fig.11 Representative images of
thickness of upper epidermis around wound tissue sections in different
treatment groups stained by H&E on day 7 (Scale bar ¼
200μm). (A)Representative images of wound tissue sections
stained by H&E in different treatment groups on day 14 (Scale bar ¼
200μm and 10 μm). (B) Quantification of the
epidermis thickness in different treatment groups on day 14 (n ¼ 3).
Data represent mean \(\pm\) SD; *, P < 0.05, **, P <0.01, ***, P <
0.001.
However, the performance of epithelial regeneration cannot directly
correspond to the overall length of healing cycle, it can only reflect
the situation of re-epithelialization in the process of wound healing.
In general, there are crosses and intersections in all 4 stages of
healing. Therefore, in the next section, this paper discussed the
indexes including collagen
deposition, collagen types and content during the healing process
combined with microscopic structures stained by Masson in detail.
Collagen distribution during wound healing
In order to analyze the healing behavior of collagen on the
3rd day after the first laser treatment in detail, it
can be seen from the enlarged figure in Fig.12(A) that there were
obvious collagen fractures in all groups on the third day, among which
the control group had the most significant collagen deposition, the 90°
laser group had the most significant collagen deposition, and the 30°
laser group had the denser morphology of healing. The red fracture is
not obvious, while the 60° laser group has a uniform distribution of
fractures [48]. We calculated the collagen content
and deposition in the wound area, as shown in Fig.12(B) and (C). The
collagen content in the laser affected area of the 90° laser group was
as high as 42.6%, and there was also significant deposition area, which
reached 36% of the laser affected area, second only to the 60° laser
group. Although the collagen content of the 30° laser group reached
34.5%, the deposition area only accounted for 26.3%, indicating that
under the laser with large incident angle, there was a tendency to form
a dense collagen network structure at this time point, which also
explained that the laser affected area of this group of samples was
abnormally fine 14 days after healing in Figure 9. In the samples of
laser group, the proportion of collagen fractional area was the largest
in 60° laser group, which exceeded 40%. However, according to the above
analysis, from the collagen distribution behavior in
14th day of healing (as shown in Fig.13(C)), the
collagen network of samples of this group was dense, which was not an
optimal healing performance. While the collagen fractional area of 60°
laser group only occupies 34.8%, at 14th day,
however, the collagen network structure and fibroblast level of samples
in this group were most similar to normal tissues, indicating that the
follow-up outstanding healing state could be anticipated by the range of
the collagen fractional area, the range could be between
26.3%~40%.