Processed allografts and type I collagen conduits for repair of peripheral nerve gaps

Abstract

Autografting is the gold standard in the repair of peripheral nerve injuries that are not amenable to end-to-end coaptation. However, because autografts result in donor-site defects and are a limited resource, an effective substitute would be valuable. In a rat model, we compared isografts with Integra NeuraGen (NG) nerve guides, which are a commercially available type I collagen conduit, with processed rat allografts comparable to AxoGen's Avance human decellularized allograft product. In a 14-mm sciatic nerve gap model, isograft was superior to processed allograft, which was in turn superior to NG conduit at 6 weeks postoperatively (P < 0.05 for number of myelinated fibers both at midgraft and distal to the graft). At 12 weeks, these differences were no longer apparent. In a 28-mm graft model, isografts again performed better than processed allografts at both 6 and 22 weeks; regeneration through the NG conduit was often insufficient for analysis in this long graft model. Functional tests confirmed the superiority of isografts, although processed allografts permitted successful reinnervation of distal targets not seen in the NG conduit groups. Processed allografts were inherently non-immunogenic and maintained some internal laminin structure. We conclude that, particularly in a long gap model, nerve graft alternatives fail to confer the regenerative advantages of an isograft. However, AxoGen processed allografts are superior to a currently available conduit-style nerve guide, the Integra NeuraGen. They provide an alternative for reconstruction of short nerve gaps where a conduit might otherwise be used.

Decellularisation and histological characterisation of porcine peripheral nerves

“…The study proposed that the presence of intact basal lamina within the acellular nerve graft contributes to the enhanced regenerating capacity to support axonal growth (Whitlock et al, 2009). The method developed by Hudson et al (2004) is currently licensed by AxoGen ® Inc. to produce Avance ® .…”

“…Current data suggests the Avance ® Nerve Graft implants increases reinnervation and improves clinical outcome when compared to commercial available NGCs (Whitlock et al, 2009). A multicentre study using Avance ® Nerve Graft showed that out of all other commercially available products it was the only one that had the ability to support repair in motor, sensory and mixed nerve types, as well as having the ability to repair both short (5–14 mm), medium (15–29 mm), and long (30–50 mm) nerve gaps, making it comparable to an autograft (Brooks et al, 2012).…”

Schwann-cell cylinders grown inside hyaluronic-acid tubular scaffolds with gradient porosity

“…Decellularized grafts and biomaterial-based nerve conduits to regenerate nervous system pathways (especially peripheral nerves) have been proposed as a promising tool in the last decades, but results rarely show a significant improvement compared with mere epineural suture or autografts [18,28,55], in particular for PNS human models [56] or CNS repair procedures [11,57]. Even more sophisticated and long-term in vivo experiments have not obtained remarkable functional restoration [9,58].…”

Decellularized grafts with axially aligned channels for peripheral nerve regeneration

“…Several studies have reported that decellularized allografts have consistently performed better than other commercially available grafts, which is most likely due to these grafts possessing the necessary architecture and guidance cues from nerve ECM components to promote axon regeneration (Karabekmez et al, 2009;Kehoe et al, 2012;Whitlock et al, 2009). A majority of protocols that decellularize nerve grafts are based on those developed by Sondell et al (Sondell et al, 1998) and Hudson et al(Hudson et al, 2004b) that predominantly use chemical decellularization agents.…”