A Human Hair Keratin Hydrogel Scaffold Enhances Median Nerve Regeneration in Nonhuman Primates: An Electrophysiological and Histological Study

Abstract

A human hair keratin biomaterial hydrogel scaffold was evaluated as a nerve conduit luminal filler following median nerve transection injury in 10 Macaca fascicularis nonhuman primates (NHP). A 1 cm nerve gap was grafted with a NeuraGen® collagen conduit filled with either saline or keratin hydrogel and nerve regeneration was evaluated by electrophysiology for a period of 12 months. The keratin hydrogel-grafted nerves showed significant improvement in return of compound motor action potential (CMAP) latency and recovery of baseline nerve conduction velocity (NCV) compared with the saline-treated nerves. Histological evaluation was performed on retrieved median nerves and abductor pollicis brevis (APB) muscles at 12 months. Nerve histomorphometry showed a significantly larger nerve area in the keratin group compared with the saline group and the keratin APB muscles had a significantly higher myofiber density than the saline group. This is the first published study to show that an acellular biomaterial hydrogel conduit filler can be used to enhance peripheral nerve regeneration and motor recovery in an NHP model.

Alkylation of human hair keratin for tunable hydrogel erosion and drug delivery in tissue engineering applications

“…Keratins used without modification or delivery of therapeutic agents have been described for biomedical applications including skin [14], hemostasis [15], bone [16], and nerve [17, 18]. We and others have also reported the use of keratins to promote delivery of therapeutics including model drugs [19], antibiotics [20, 21], and recombinant human bone morphogenetic protein 2 (rhBMP-2) [22–24]…”

Delivery of adipose‐derived stem cells in poloxamer hydrogel improves peripheral nerve regeneration

“…Currently, none of these guides have been shown to be an improvement compared with autograft outcomes, although several have had positive outcomes . Efforts to augment these guides for improved efficacy are underway, including the use of transplanted adult mesenchymal stem cells (MSC) within these guides …”

“…Hydrogels represent a method of cell delivery that overcomes many of the obstacles associated with current delivery methods. They localize and support transplanted cells at the repair site and can act as internal scaffolds within nerve conduits. Poloxamer 407 is an US Food and Drug Administration‐approved biocompatible, bioabsorbable pharmaceutical additive that reversibly gels without cross‐linking on temperature increase and dissolves in vivo over time by simple surface absorption and renal clearance .…”

Strategies to improve nerve regeneration after radical prostatectomy: a narrative review

“…Other natural proteins like keratins have also been tested as nerve scaffold materials [75,76] or as filler to support peripheral nerve regeneration [77].…”