Characterization and Schwann Cell Seeding of up to 15.0 cm Long Spider Silk Nerve Conduits for Reconstruction of Peripheral Nerve Defects

Abstract

Nerve reconstruction of extended nerve defect injuries still remains challenging with respect to therapeutic options. The gold standard in nerve surgery is the autologous nerve graft. Due to the limitation of adequate donor nerves, surgical alternatives are needed. Nerve grafts made out of either natural or artificial materials represent this alternative. Several biomaterials are being explored and preclinical and clinical applications are ongoing. Unfortunately, nerve conduits with successful enhancement of axonal regeneration for nerve defects measuring over 4.0 cm are sparse and no conduits are available for nerve defects extending to 10.0 cm. In this study, spider silk nerve conduits seeded with Schwann cells were investigated for in vitro regeneration on defects measuring 4.0 cm, 10.0 cm and 15.0 cm in length. Schwann cells (SCs) were isolated, cultured and purified. Cell purity was determined by immunofluorescence. Nerve grafts were constructed out of spider silk from Nephila edulis and decellularized ovine vessels. Finally, spider silk implants were seeded with purified Schwann cells. Cell attachment was observed within the first hour. After 7 and 21 days of culture, immunofluorescence for viability and determination of Schwann cell proliferation and migration throughout the conduits was performed. Analyses revealed that SCs maintained viable (>95%) throughout the conduits independent of construct length. SC proliferation on the spider silk was determined from day 7 to day 21 with a proliferation index of 49.42% arithmetically averaged over all conduits. This indicates that spider silk nerve conduits represent a favorable environment for SC attachment, proliferation and distribution over a distance of least 15.0 cm in vitro. Thus spider silk nerve implants are a highly adequate biomaterial for nerve reconstruction.

Nerve grafting for peripheral nerve injuries with extended defect sizes

“…Results indicates that nerve regeneration through the spider silk nerve implant is at least as effective as autologous nerve grafts. The spider silk conduit was designed and prior to application in large animal model extensively tested in vitro and in small animal models in vivo [ 82 – 86 ]. Especially results of the current in vitro investigation of the spider silk based nerve implant emphasize that the implant might be suitable for nerve reconstruction on defect sides extending 6.0 cm in length [ 82 ].…”

“…The spider silk conduit was designed and prior to application in large animal model extensively tested in vitro and in small animal models in vivo [ 82 – 86 ]. Especially results of the current in vitro investigation of the spider silk based nerve implant emphasize that the implant might be suitable for nerve reconstruction on defect sides extending 6.0 cm in length [ 82 ]. Outcome of previous the in vitro study are currently being reevaluated in the ovine animal model [ 82 ].…”

“…Especially results of the current in vitro investigation of the spider silk based nerve implant emphasize that the implant might be suitable for nerve reconstruction on defect sides extending 6.0 cm in length [ 82 ]. Outcome of previous the in vitro study are currently being reevaluated in the ovine animal model [ 82 ]. Results of these in vivo investigation are pending.…”

Co-Culturing Human Adipose Derived Stem Cells and Schwann Cells on Spider Silk—A New Approach as Prerequisite for Enhanced Nerve Regeneration

“…Treatment of nerve defect injuries by autologous nerve transplantation represents the gold standard when a tension-free end-to-end coaptation is not achievable. However, with regard to donor site morbidity, nerve availability is limited [2,6,7,8,9].…”

“…In the last years, many studies focused on finding valid alternatives. Nerve conduits made of biodegradable materials were developed as guiding channels for regenerating axons and redirect proximal nerve growth [2,4,6,7,8,9,10]. In some cases, conduits were filled with hydrogels or similar materials or neurotrophic factors to further improve and enhance recovery in peripheral nerve gap injuries.…”