TABLE 3.

The effect of different cell therapies on Schwann cells for diabetic neuropathy.

Stem cell type	Cell source	Effect on Schwann cells	Notes
MNCs	Bone marrow/peripheral blood	Increased angiogenic and neurotrophic factor release (Hasegawa et al., 2006; Kim et al., 2009)	• Implantation into hindlimb muscles in STZ-induced diabetic rats; • Improvement in vascularity and motor nerve conduction velocity
EPCs	Bone marrow (Jeong et al., 2009)/ cord blood (Naruse et al., 2005)	• Decreased Schwann cells apoptosis and enhanced proliferation (Naruse et al., 2005; Jeong et al., 2009)	• Cell were injected into the hindlimb of STZ-induced diabetic mice or rats; • Enhancement in neural neovascularization and neuroprotective effects
BMSCs	Bone marrow	• Differentiation into Schwann cell-like cells and the upregulation of neurotrophic factors and myelination-related genes (Han et al., 2016)	• Injection into the hindlimb muscles of STZ-induced diabetic rats; • Increases in angiogenesis, neural function and myelination
ASCs	Adipose tissue	• Effects on the Schwann cell signal network, including neurotrophic effects and the restoration of myelination (Yigitturk et al., 2021)	• Injection into the thigh and lower hind-leg muscles of STZ-induced diabetic mice; • Restoration of neural structure and function
		• Reduced Schwann cell apoptosis with ASCs-conditioned medium (De Gregorio et al., 2020)	• Systemic administration in diabetic BKS db/db mice; • Avoiding foot ulcer formation and ameliorating polyneuropathy
DPSCs	Teeth	• Increased viability and myelin-related protein expression in Schwann cells (Omi et al., 2017) • Promotion of Schwann cells proliferation and myelin formation (Omi et al., 2017)	• Transplantation of human DPSCs into the hindlimb skeletal muscles of STZ-induced diabetic nude mice; • Treatment of diabetic polyneuropathy via the angiogenic and neurotrophic mechanism of hDPSC-secreted factors (Hata et al., 2020)
			• Transplantation of rat DPSCs into the hindlimb skeletal muscles of STZ-induced diabetic rats; • Improvements in long-term diabetic polyneuropathy (Omi et al., 2017)
			• Transplantation of freshly isolated and cryopreserved rat DPSCs into the hindlimb skeletal muscles of STZ-induced diabetic rats; • Amelioration of diabetic polyneuropathy (Hata et al., 2015)
			• Transplantation of rat DPSCs or administration of secreted factors into the hindlimb skeletal muscles of STZ-induced diabetic rats; • Amelioration of diabetic polyneuropathy with either treatment (Kanada et al., 2020)
			• Transplantation into STZ-induced neuropathic rats through the intramuscular or intravenous route via a single or two repeat doses; • Contribution to functional recovery with all treatments, but repeated doses via the intramuscular route was the most effective (Datta et al., 2017)
Neural crest cells	Induced pluripotent stem cells	Differentiation into Schwann cell-like cells (Bronner and LeDouarin, 2012)	• Transplantation into the hindlimb skeletal muscles of STZ-diabetic mice; • Improvement in impaired vascular and neuronal functions (Okawa et al., 2013)