Micropatterns and peptide gradient on the inner surface of a guidance conduit synergistically promotes nerve regeneration in vivo

Both of the surface topographical features and distribution of biochemical cues can influence the cell-substrate interactions and thereby tissue regeneration in vivo.However,they have not been combined simultaneously onto a biodegradable scaffold to demonstrate the synergistic role so far.In this study,a proof-of-concept study is performed to prepare micropatterns and peptide gradient on the inner wall of a poly(D,L-lactide-co-caprolactone)(PLCL)guidance conduit and its advantages in regeneration of peripheral nerve in vivo.After linear ridges/grooves of 20/40μm in width are created on the PLCL film,its surface is aminolyzed in a kinetically controlled manner to obtain the continuous gradient of amino groups,which are then transferred to CQAASIKVAV peptide density gradient via covalent coupling of glutaraldehyde.The Schwann cells are better aligned along with the stripes,and show a faster migration rate toward the region of higher peptide density.Implantation of the nerve guidance conduit made of the PLCL film having both the micropatterns and peptide gradient can significantly accelerate the regeneration of sciatic nerve in terms of rate,function recovery and microstructures,and reduction of fibrosis in muscle tissues.Moreover,this nerve conduit can also benefit the M2 polarization of macrophages and promote vascularization in vivo.