Table 5.

Summary of the included studies and the effect of combinatory cell therapy for SCI.

Type of Grafted Cells	Biomaterial Scaffold	Results/Advantages	Limitations/Disadvantages
NPCs	PLGA scaffold HA scaffold Protein-functionalized chitosan scaffold 3D biomimetic hydroge Collagen microchannel scaffold 3D printed heparin sulfate-collagen scaffold Exosomes-collagen scaffold Multi-channel collagen scaffold Aligned collagen scaffold Polymer scaffold Chitosan channels scaffold Protein-functionalized chitosan scaffold Laminin-coated pHEMA-MOETACl Hydrogel Artificial microfiber scaffold Polycaprolactone electrospun fiber scaffold Fibrin scaffold SAP scaffold Matrigel scaffold	Functional recovery Graft cells survival and neuronal cell differentiation Secretion of trophic factors Protection of host neuronal cells Axonal outgrowth through injured lesion Remyelination of host axons Neuronal differentiation Host cells survival	Immune rejection Tumorgenesis
BMCSs	Chitosan-based thermosensitive scaffold Chitosan conduits scaffold Alginate hydrogel biomaterial PLGA scaffold Collagen scaffold Collagen filaments scaffold Porous collagen scaffold NeuroRegen scaffold PLGA scaffold HA-PLL scaffold SAP hydrogel scaffold Biologic scaffolds derived from fibrin and blood plasma Goldnanoparticles (Au NPs)-loaded Agarose/Poly (N- isopropylacrylamide) (PNIPAM) Thermosensitive quaternary ammonium chloride chitosan/β-glycerophosphate (HACC/β-GP) hydrogel scaffold Gelatin sponge scaffold Nanofibrous silk scaffold Cylindrical poly(D,L-lactide-co-glycolide)/small intestinal submucosa scaffold PHEMA scaffold	Functional recovery Repair of spinal cord injury Secretion of trophic factors Protection of host neuronal cells Axonal outgrowth Remyelination of host axons Host cells survival Low risk of immune rejection Autologous transplants No ethical issues	Difficulty of neuronal differentiation Low cell survival rate
Umbilical MSCs/Wharton’s jelly-derived MSCs	Collagen scaffold 3D printed collagen/silk fibroin scaffold HA-PH modified with the integrin-binding peptide arginine-glycine-aspartic acid scaffold
Adipose-derived stem/stromal cells	Silk fibroin/chitosan scaffold Matrigel scaffold Resorbable poly(α-hydroxyacid) guidance channels scaffold
Schwann cells (SCs)	Biodegradable poly-b-hydroxybutyrate scaffold Oligo[poly(ethylene glycol) fumarate] scaffold	Axon growth into SCs implants Ensheathment and myelination No tumorigenicity Modest but significant motor and sensory improvement SCs-elicited responses such as survivability post-transplantation, axon growth, and functional recovery can be improved with appropriate combination treatments Remyelination Functional recovery Secretion of trophic factors	No differentiation into neurons and astrocytes
OECs	PLGA Scaffold	Functional recovery Promotion of cell differentiation Inhibition of astrocyte formation Accelerate neuronal regeneration Secrete nerve growth factors Decrease neuronal apoptosis Reduce glial scaring Produce a number of trophic factors such as VEGF Constitute the myelin and the Ranvier nodes of the axons	No differentiation into neurons and astrocytes
Spinal cord-derived ependymal progenitor cells	HA containing PLA fibers scaffold	Preserve the neuronal tissue Diminish astrocytic reactivity surrounding the scar area Axonal outgrowth	No functional recovery
Dental pulp stem cells/Dental follicle cells	Chitosan scaffolds Aligned electrospun PCL/PLGA material scaffold	Increase the levels of BDNF, GDNF, beta-NGF and NT-3 Recovery of hind limb locomotor functions	No differentiation into neurons and astrocytes
NPCs and Schwann cells	3D bioprinting of NSC-laden HBC/HA/MA scaffold PLGA scaffolds Biodegradable polymer scaffold Poly (L-lactic-co-glycolic acid) scaffold	Provision of an ideal microenvironment for the growth and neural differentiation of grafted cells. Restoration of locomotor function Simulation of the parallel linear structure of spinal cord for optimal neuron regeneration and connection.	Immune rejection Tumorgenesis
BMSCs and Schwann cells	Multichannel polymer scaffold	Functional recovery Secretion of trophic factors Protection of host neuronal cells Axonal outgrowth through injured lesion Remyelination of host axons	No differentiation into neurons and astrocytes
Endometrial stem cells and Schwann cells	Degradable polymer implant PCL/gelatin nanofibrous scaffold	Functional recovery Secretion of trophic factors Protection of host neuronal cells Axonal outgrowth through injured lesion Remyelination of host axons Host cells survival	No differentiation into neurons and astrocytes
Dermal fibroblast-reprogrammed neurons	3D silk fibrous material	Functional recovery Axonal outgrowth through injured lesion Remyelination of host axons	No differentiation into neurons and astrocytes
Adipose-derived stem cells and OECs	Serum-derived albumin scaffold	Functional recovery Secretion of trophic factors Protection of host neuronal cells Axonal outgrowth through injured lesion Remyelination of host axons	No differentiation into neurons and astrocytes
NPCs and MSCs	3D longitudinal scaffold	Functional recovery Graft cells survival and neuronal cell differentiation Secretion of trophic factors Protection of host neuronal cells Axonal outgrowth through injured lesion Remyelination of host axons Neuronal differentiation Host cells survival	Immune rejection Tumorgenesis