Fig. 4: Biocompatibility of long-term FIMOSS implantation in brachial plexus after 12 weeks.

a Timeline of FIMOSS implantation and biocompatibility experiments. b Intraoperative images of the FIMOSS implant 12 weeks after implantation surgery. The PDMS encapsulation was observed to be intact after removing the thin layer of connective tissue encapsulation. c Intraoperative images of MOSD II and brachial plexus 12 weeks after implantation surgery. The texture and continuity of middle trunks and adjected upper and lower trunks were not affected by the implantation of MOSD II. d Immunofluorescent image of middle trunks at the implantation (main trunk) and distal site (nerve branches) of MOSD II. No obvious inflammation response can be observed. (scale bar = 100 μm) (n = 6). e A Schematic of motion analysis experiment set-up. f, g Representative trajectories of forelimb movements in mice from control group without FIMOSS implant (f) and middle trunk implantation group with an FIMOSS implant 12 weeks after implantation (g). Several gait cycles were showed in the image. Golden and black lines represented the forelimb trajectory of lifting and landing process (swing phase). Red lines represent the stance phase. Comparison between range of motions of shoulder (h), elbow (i), wrist (j), and MP joint (k) in different groups in motion analysis experiments. l, m A Representative photograph of walking tracks captured by the gait analysis system. Quantification analysis shows base of support (n), stride length (o), print area (p), stance time (q), and swing time (r) of right forelimb were not significantly affected when a FIMOSS implant was implanted onto the upper, middle, lower trunks on the right side. n = 4 for each group in motion analysis (h–k). n = 5 for each group in gait analysis (n–r). One-way ANOVA and multiple comparison tests with Dunnett’s correct. Data are presented as mean ± s.e.m.