TABLE 1.

The effect of Schwann cell therapy on peripheral nerve injury-induced neuropathy.

Model	Schwann cell source	Outcomes	Notes
Rat sciatic nerve defect with an 8 mm gap	Autologous	Extensive peripheral nerve regeneration and myelination	• A strong immune reaction occurred when seeding with heterologous Schwann cells; • Seeding density of Schwann cells should be considered (Guenard et al., 1992)
Sciatic nerve defect with a 5 mm gap in immune-deficient rats	Allogeneic, from human nerves	Promotion of axonal regeneration and myelination	Repair outcomes were better than the channels with Matrigel solution alone (Levi et al., 1994)
Human sciatic nerve defect with a 7.5 cm gap	Autologous	Proximal sensory recovery, including neuropathic pain, and motor function recovery in the common peroneal and tibial distribution	The patient suffered complete transection of sciatic nerves by a boat propeller injury (Levi et al., 2016)
Human sciatic nerve defect with a 5 cm gap	Autologous	Recovery of complete motor function and partial sensation in the tibial distribution	The patient suffered partial damage of the tibial division of sciatic nerves by a gun wound to the leg (Gersey et al., 2017)
Mouse sciatic nerve crush	Allogeneic, from human skin	Promotion of axonal regrowth and myelination	• Adult human skin-derived Schwann cells were similar to human nerve-derived Schwann cells in genetical and phenotypical characterization; • Highly accessible source of autologous skin-derived Schwann cells was a substitute for nerve-derived Schwann cells for injured nerve repair (Stratton et al., 2017)
Rat sciatic nerve defect with a 10 mm gap	Allogeneic, from neonatal rat sciatic nerves	Improvement in axonal regeneration	• The quantity of regenerated axons was less than that induced by treatment with syngeneic Schwann cells; • Immune response occurred at 6 weeks post-transplantation in the absence of immunosuppressive therapy (Mosahebi et al., 2002)
Rat sciatic nerve defect with a 20 mm gap (Hoben et al., 2015), 10 mm gap (Sun et al., 2009) and 14 mm gap (Santosa et al., 2013)	Allogeneic, from neonatal (Sun et al., 2009; Hoben et al., 2015)/adult (Santosa et al., 2013) rat sciatic nerves	Improvement in axonal regeneration (Sun et al., 2009; Santosa et al., 2013; Hoben et al., 2015) and myelination (Sun et al., 2009)	• Acellular nerve allografts combined with allogeneic Schwann cells obtained the same outcomes as the isograft group (Hoben et al., 2015); • Adding vascular endothelial growth factor alone (Hoben et al., 2015) or Schwann cells overexpressing glial cell-derived neurotrophic factor (Santosa et al., 2013) in acellular nerve allografts had reduced effects on improving axonal regeneration
Rat sciatic nerve injury with a 3 cm gap	Autologous, from the proximal stump neuroma	Regenerative fibers crossing the entire distance but no motor and poor sensory function recovery	It is challenging to regenerate axons with a 3 cm gap defect with only grafts (Aszmann et al., 2008)
Primate ulnar nerve defect with a 6 cm gap	Autologous, from the sural nerve fascicles	Low immune response and significant regeneration	Cold-preserved allografts combined with autologous Schwann cells was a potentially safe and effective alternative to autografts (Hess et al., 2007)
Rabbit peroneal nerve defect with a 6 cm gap	Autologous, from the contralateral peroneal nerve	Excellent growth of axons targeting the distal end	Autologous Schwann cells break the limit of nerve regeneration by an empty autogenous venous nerve conduit (Strauch et al., 2001)
Rat sciatic nerve defect with a 10 mm gap (Mosahebi et al., 2002) and 1 cm gap (Bryan et al., 2000; Tohill et al., 2004; di Summa et al., 2011)	Allogeneic, from rat sciatic nerves	Improvements in axonal regrowth and fiber myelination	Combination with allogeneic Schwann cells obtained better outcomes in synthetic grafts, such as polyhydroxybutyrate conduits (Mosahebi et al., 2002; Tohill et al., 2004), fibrin conduits (di Summa et al., 2011) and poly (lactic-co-glycolic) acid conduits (Bryan et al., 2000)