Transplantation of Schwann cells in a collagen tube for the repair of large, segmental peripheral nerve defects in rats

Object Segmental nerve defects pose a daunting clinical challenge, as peripheral nerve injury studies have established that there is a critical nerve gap length for which the distance cannot be successfully bridged with current techniques. Construction of a neural prosthesis filled with Schwann cells (SCs) could provide an alternative treatment to successfully repair these long segmental gaps in the peripheral nervous system. The object of this study was to evaluate the ability of autologous SCs to increase the length at which segmental nerve defects can be bridged using a collagen tube. Methods The authors studied the use of absorbable collagen conduits in combination with autologous SCs (200,000 cells/μl) to promote axonal growth across a critical size defect (13 mm) in the sciatic nerve of male Fischer rats. Control groups were treated with serum only–filled conduits of reversed sciatic nerve autografts. Animals were assessed for survival of the transplanted SCs as well as the quantity of myelinated axons in the proximal, middle, and distal portions of the channel. Results Schwann cell survival was confirmed at 4 and 16 weeks postsurgery by the presence of prelabeled green fluorescent protein–positive SCs within the regenerated cable. The addition of SCs to the nerve guide significantly enhanced the regeneration of myelinated axons from the nerve stump into the proximal (p < 0.001) and middle points (p < 0.01) of the tube at 4 weeks. The regeneration of myelinated axons at 16 weeks was significantly enhanced throughout the entire length of the nerve guide (p < 0.001) as compared with their number in a serum–only filled tube and was similar in number compared with the reversed autograft. Autotomy scores were significantly lower in the animals whose sciatic nerve was repaired with a collagen conduit either without (p < 0.01) or with SCs (p < 0.001) when compared with a reversed autograft. Conclusions The technique of adding SCs to a guidance channel significantly enhanced the gap distance that can be repaired after peripheral nerve injury with long segmental defects and holds promise in humans. Most importantly, this study represents some of the first essential steps in bringing autologous SC-based therapies to the domain of peripheral nerve injuries with long segmental defects

SNP markers tightly linked to root knot nematode resistance in grapevine (<i>Vitis cinerea</i>) identified by a genotyping-by-sequencing approach followed by Sequenom MassARRAY validation

<div><p>Plant parasitic nematodes, including root knot nematode <i>Meloidogyne</i> species, cause extensive damage to agriculture and horticultural crops. As <i>Vitis vinifera</i> cultivars are susceptible to root knot nematode parasitism, rootstocks resistant to these soil pests provide a sustainable approach to maintain grapevine production. Currently, most of the commercially available root knot nematode resistant rootstocks are highly vigorous and take up excess potassium, which reduces wine quality. As a result, there is a pressing need to breed new root knot nematode resistant rootstocks, which have no impact on wine quality. To develop molecular markers that predict root knot nematode resistance for marker assisted breeding, a genetic approach was employed to identify a root knot nematode resistance locus in grapevine. To this end, a <i>Meloidogyne javanica</i> resistant <i>Vitis cinerea</i> accession was crossed to a susceptible <i>Vitis vinifera</i> cultivar Riesling and results from screening the F₁ individuals support a model that root knot nematode resistance, is conferred by a single dominant allele, referred as <i>MELOIDOGYNE JAVANICA RESISTANCE1 (MJR1)</i>. Further, <i>MJR1</i> resistance appears to be mediated by a hypersensitive response that occurs in the root apical meristem. Single nucleotide polymorphisms (SNPs) were identified using genotyping-by-sequencing and results from association and genetic mapping identified the <i>MJR1</i> locus, which is located on chromosome 18 in the <i>Vitis cinerea</i> accession. Validation of the SNPs linked to the <i>MJR1</i> locus using a Sequenom MassARRAY platform found that only 50% could be validated. The validated SNPs that flank and co-segregate with the <i>MJR1</i> locus can be used for marker-assisted selection for <i>Meloidogyne javanica</i> resistance in grapevine.</p></div