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International Journal of Bioprinting 3D printed bioactive dressings for burn wound treatment

Figure 9. In vivo burn wound closure of the dressings in the control and test groups. 3D-printed dressings with BBG showed the fastest wound closure (i.e.,
smaller wound size) after 28 days, followed by 3D-printed hydrogel and non-printed hydrogel–BBG dressings. n = 6; *P < 0.05, **P < 0.01, ***P < 0.001,
and NS denotes non-significant difference.

Table 3. Wound assessment for different study groups
Moist wound Granulation tissue Re-epithelialization
Dressing Wound margins
healing (days 14 and 21) (days 21 and 28)
Control Not seen 3-2 2-2 Red—Thick crust
BBG powder Not seen 4-3 1-3 Brown—Thick crust
Non-printed hydrogel Partially seen 3-2 2-4 Pink—Sloping

Non-printed hydrogel–BBG20 Seen 2-0 4-4 Light pink—Smooth, flat
3D-printed hydrogel Seen 3-1 3-4 Pink—Smooth, flat
3D-printed hydrogel–BBG20 Seen 2-0 4-4 Light pink—Smooth, flat

samples, regardless of the formulation, increased the highest GT on day 28, confirming poor wound closure in
regeneration of skin appendages by providing a favorable this sample (Figure 8). More specifically, GT refers to the
interface for cell–material interaction within the pores. The chronically vascularized tissue that represents persistent
non-printed hydrogel–BBG samples, 3D-printed hydrogel, inflammation, mainly composed of pink and granular
and hydrogel–BBG dressings showed higher numbers tissue with macrophages and proliferating fibroblasts .
[84]
and faster regeneration of hair follicles compared to the The persistence of GT at week 4 represents the immature
other samples. The non-printed and 3D-printed hydrogel– wound healing and failed treatment. All samples showed
BBG20 dressings developed thicker and more hair follicles slight GT formation compared to the control groups,
toward the epidermal layer, while in the BBG powder, non- showing that both 3D-printed porous texture and BBG
printed hydrogel, and 3D-printed hydrogel groups, the hair content positively affected tissue regeneration. Recent
follicles were shorter, and still in the dermal layer, indicating
slower growth and development of hair follicles. Therefore, research showed that a reduction in the formation of GT is
[85]
the synergistic effect of BBG and 3D-printed porous associated with improved scar outcomes . The 3D-printed
surface enhanced the regeneration of follicles in terms of samples with and without BBG showed uniform dermal
population and growth rate. The presence of GT after 21 regeneration that can be associated with the 3D-printed
days is a major indication of immature wound healing and porous pattern in these samples. Our findings confirmed
prolonged tissue regeneration. Further, more sweat glands that the favorable degradation rate, controlled water release,
and skin appendages (yellow arrowheads) appeared in all skin-like mechanical properties, and porous non-adhesive
groups, with slightly higher regeneration in the 3D-printed contact surface in 3D-printed hydrogel–BBG20 dressings
hydrogel–BBG20 group. The control group showed the could promote the outcomes of burn wound healing.

Volume 9 Issue 6 (2023) 145 https://doi.org/10.36922/ijb.0118