5. Subcutaneous transplantation of 3D-printed scaffold
Since the in vivo assessment of a potential biomaterial is focused on clinical applications, it must be noted that the developed biomaterial should be considered biocompatible without toxicity or any other adverse clinical effects after interaction
within the living systems. During the in vivo implantation study, the materials were subcutaneously implanted into the back of the experimental rats under anaesthesia. None of the rats displayed visible signs of inflammation (such as redness, heat, swelling, pain, loss of appetite, and reduced mobility) during the post-implantation period. Surgical sites on all animals appeared normal post-implantation. Upon collecting the samples, no apparent tissue hyperplasia and suppuration were noted in the area surrounding the implant, and no apparent immune rejection reaction was noted between the surrounding tissues and the material (Figure 15).
The tissues collected from animals 2 weeks after the implantation were sectioned and stained with H&E to investigate the cellular inflammatory response to the implanted materials (Figure 16). Comparison between freeze-drying and oven-drying processes revealed no significant difference in the inflammatory status in this study, indicating no effect of the drying preparation method used. The histological sections of the K group were characterised by a large number of inflammatory cells. Some abscess areas were noted. Inflammation was found to be severe, with a large number of neutrophils. The kc group showed marked inflammatory and cellular changes in the epidermis in the presence of neutrophils and mononuclear cells along with oedematous eosinophilic exudate. Moreover, inflammation was nonsignificant or moderate in most sections. The HE-stained sections confirmed the biocompatibility of the ks group with the connective tissues. At day 14, small areas exhibited neutrophil regions. Inflammation was nonsignificant in most sections.