Biomaterials and Stem Cell Therapies for Injuries Associated to Skeletal Muscular Tissues - Advances in Biomaterials Science and Biomedical Applications - page 351

iii. the number and distribution as a function of distance from the material/tissue in‐

terface of the inflammatory cell types, namely polymorph nuclear neutrophilic leu‐
cocytes, lymphocytes, plasma cells, eosinophils, macrophages and multinucleated
cells;

iv. the presence, extent and type of necrosis;

v. other tissue alterations such as vascularization, fatty infiltration, granuloma forma‐

tion and bone formation;

vi. the material parameters such as fragmentation and/or debris presence, form and lo‐

cation of remnants of degraded material;

vii. the quality and quantity of tissue ingrowth, for porous and degradable implant

materials [106].

Under the conditions of the study and following the results for the mentioned parameters in
the semi-quantitative scoring system (Annex E of this Sandard), the test sample is consid‐
ered as non-irritant (0,0 up to 2,9), slight irritant (3,0 up to 8,9), moderate irritant (9,0 up to
15,0), severe irritant (> 15) to the tissue as compared to the negative control sample [106].
This test method is used for assessing the biological response of muscle tissue to an implant‐
ed material (Annex C of this Standard). As already mentioned, the method compares the bi‐
ological response to implants of test specimens with the biological response to implants of
control specimens. The control materials are those used in medical devices of which the clin‐
ical acceptability and biocompatibility characteristics have been established [106]. In our
study we developed an adaptation of this Standard by considering the control as the group
where the surgical procedure (myectomy) was performed without any biomaterial or cell
implantation (Figure 6). Although the surgical technique may profoundly influence the re‐
sult of any implantation procedure, we assumed that our standardized myectomy lesion
could be considered as the Control group since we were able to determine the local effects of
the different implants by their comparison to the minor effects of the surgical procedure.
The surgeries were executed under general anesthesia with a xylazine (1.25 mg/100 g BW
im) and ketamine (9 mg/100 g BW im) combination [38].

Figure 6. ISO 10993-6 scoring for the groups tested. The Control group obtained a score of 14.7 (in blue). Scorings above
the Control group were considered as non-irritant (in yellow), slight irritant (in orange) and moderate irritant (in red).