Use of PLGA 90:10 Scaffolds Enriched withIn Vitro–Differentiated Neural Cells for Repairing Rat Sciatic Nerve Defects

Abstract

Poly(lactic-co-glycolic acid) (PLGA) nerve tube guides, made of a novel proportion (90:10) of the two polymers, poly(L-lactide): poly(glycolide) and covered with a neural cell line differentiated in vitro, were tested in vivo for promoting nerve regeneration across a 10-mm gap of the rat sciatic nerve. Before in vivo testing, the PLGA 90:10 tubes were tested in vitro for water uptake and mass loss and compared with collagen sheets. The water uptake of the PLGA tubes was lower, and the mass loss was more rapid and higher than those of the collagen sheets when immersed in phosphate-buffered saline (PBS) solution. The pH values of immersing PBS did not change after soaking the collagen sheets and showed to be around 7.4. On the other hand, the pH values of PBS after soaking PLGA tubes decreased gradually during 10 days reaching values around 3.5. For the in vivo testing, 22 Sasco Sprague adult rats were divided into four groups--group 1: gap not reconstructed; group 2: gap reconstructed using an autologous nerve graft; group 3: gap reconstructed with PLGA 90:10 tube guides; group 4: gap reconstructed with PLGA 90:10 tube guides covered with neural cells differentiated in vitro. Motor and sensory functional recovery was evaluated throughout a healing period of 20 weeks using sciatic functional index, static sciatic index, extensor postural thrust, withdrawal reflex latency, and ankle kinematics. Stereological analysis was carried out on regenerated nerve fibers. Both motor and sensory functions improved significantly in the three experimental nerve repair groups, although the rate and extent of recovery was significantly higher in the group where the gap was reconstructed using the autologous graft. The presence of neural cells covering the inside of the PLGA tube guides did not make any difference in the functional recovery. By contrast, morphometric analysis showed that the introduction of N1E-115 cells inside PLGA 90:10 tube guides led to a significant lower number and size of regenerated nerve fibers, suggesting thus that this approach is not adequate for promoting peripheral nerve repair. Further studies are warranted to assess the role of other cellular systems as a foreseeable therapeutic strategy in peripheral 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

“…SCs, MSCs, embryonic stem cells, marrow stromal cells are the most studied support cells candidates. The cellular systems implanted into the injured nerve may produce growth factors or extracellular matrix (ECM) molecules, or may modulate the inflammatory process, to improve nerve regeneration Gu et al, 2011;Luis et al, 2007Luis et al, , 2008aSimoes et al, 2010). To implant cultured cells into defective nerves (with axonotmesis and neurotmesis injuries), there are two main techniques.…”

“…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).…”

“…Tissue engineering of peripheral nerves associates biomaterials, like chitosan, PLC, and other biomaterials, some of them, previously studied by our group ( Amado et al, 2008;Luis et al, 2008a;Maurı´cio et al, 2011) to cellular systems, able to differentiate into neuroglial like cells or even by modulating the inflammatory process, which might improve nerve regeneration, in terms of motor and sensory recovery, and also, by shortening the healing period avoiding regional muscular atrophy. Cell transplantation has been proposed as a method of improving peripheral nerve regeneration ( Chen et al, 2007).…”