PLGA 90/10 and caprolactone biodegradable nerve guides for the reconstruction of the rat sciatic nerve

Abstract

The purpose of this study was to test in vivo two different nerve guides for promoting nerve regeneration across a 10-mm gap of the rat sciatic nerve: 1) one made of PLGA in a novel proportion (90:10) of the two polymers poly(L-lactide):poly(glycolide); 2) another made of (DL-lactide-epsilon-caprolactone) copolyester (Neurolac) tube, by comparing its healing efficacy with that of the more traditional methods of end-to-end nerve suture and autologous graft. Motor and sensory functional recovery were assessed throughout the healing period of 20 weeks, and the repaired nerves were processed for morphological and histomorphometrical analysis. Both motor and sensory functions improved significantly in all experimental nerve repaired groups. At the end of the 20-week follow-up, the end-to-end group showed better recovery of motor function when compared with the groups treated with guiding tubes. However, at this time point, the level of motor function in the Neurolac(R) and PLGA groups was similar to the one of the graft group. Nociception function also recovered faster in the end-to-end group compared with the Neurolac(R) and PLGA groups, and in this case, recovery was also delayed in the graft group. At the end of follow-up, nociception was similar in all experimental groups. Morphological and histomorphometrical analysis showed that axon regeneration occurred in both PLGA and Neurolac(R) experimental groups, with no significant differences in the total number of regenerated fibers, but disclosed a different pattern of degradation of the two types of tubes with larger biodegradation of PLGA material by the end of 20 weeks. These results suggest that both types of biomaterials are a good substrate for preparing tubular nerve guides, and their different pattern of degradation does not seem to influence the degree of nerve regeneration.

Use of poly(DL-lactide-ε-caprolactone) membranes and mesenchymal stem cells from the Wharton's jelly of the umbilical cord for promoting nerve regeneration in axonotmesis: In vitro and in vivo analysis

“…The standardized crush injury was carried out with the animals placed prone under sterile conditions and the skin from the clipped lateral right thigh scrubbed in a routine fashion with antiseptic solution. The surgery procedure was the one previously described ( Luı´s et al, 2007;Luis et al, 2007). The standard crush injury was performed by a non-serrated clamp (Institute of Industrial Electronic and Material Sciences, University of Tech-nology, Vienna, Austria), exerting a constant force of 54 N for a period of 30 s, 10 mm above the bifurcation into tibial and common peroneal nerves inducing a 3 mm axonotmesis lesion.…”

“…Motor performance and nociceptive function were evaluated by measuring extensor postural thrust (EPT) and withdrawal reflex latency (WRL), respectively ( Luis et al, 2007( Luis et al, , 2008a. For EPT test, the affected and normal limbs were tested 3 times, with an interval of 2 min between consecutive tests, and the 3 values were averaged to obtain a final result.…”

“…The nociceptive withdrawal reflex (WRL) was adapted from the hotplate test developed by Masters et al (1993) and described elsewhere ( Luis et al, 2007( Luis et al, , 2008a. Normal rats withdraw their paws from the hotplate within 4 s or less ( Hu et al, 1997).…”

“…For SFI, animals were tested in a confined walkway measuring 42 cm long and 8.2 cm wide, with a dark shelter at the end, as previously described ( Luis et al, 2007( Luis et al, , 2008a. Several mea-surements were taken from the footprints: (i) distance from the heel to the third toe, the print length (PL); (ii) distance from the first to the fifth toe, the toe spread (TS); and (iii) distance from the second to the fourth toe, the intermediary toe spread (ITS).…”

“…Focal crush causes axonal interruption but preserves the connective sheaths (axonotmesis). After this kind of injury, regeneration is usually successful, in a short latency (1-2 days), axons regenerate at a steady rate along the distal nerve supported by the reactive Schwann cells (SCs) and the preserved endoneural tubules which enhance axonal elongation and facilitate adequate reinnervation ( Luis et al, 2007).…”