Preclinical efficacy and safety assessments of Adult human neural stem cells (AhNSCs) for spinal cord injury

Abstract

Spinal cord injury (SCI) is a severe and devastating condition that leads to irreversible damage to neural tissues, creating significant medical, economic, and social challenges. The ability to differentiate into multiple neural cell types and to regulate immune response makes neural stem cells (NSC) a promising strategy for treating SCI. In this study, we investigated the therapeutic potential, safety profile, and tumorigenic risk of intrathecally transplanted adult human neural stem cells (AhNSCs) produced under clinical-grade standards in a Good Manufacturing Practice (GMP) facility, in rat SCI models, thereby laying the foundation for future clinical trials. Functional tests, including the Basso, Beattie, and Bresnahan (BBB) locomotor rating, rotarod, and von Frey tests, showed significant improvements in motor function and mechanical sensitivity in rats with SCI. Histological analysis revealed reduced tissue loss, glial scar formation, and increased axonal regeneration. Biodistribution studies indicated that the transplanted AhNSCs are primarily localized within the spinal cord, with minimal systemic distribution. Toxicity studies found no significant adverse effects, suggesting a favorable safety profile. Long-term tumorigenicity studies reported no treatment-related deaths or signs of tumor formation in either gender. In conclusion, the study demonstrates that AhNSCs offer promising therapeutic potential for treating SCI, contributing to improved motor function and sensory recovery. These findings support further investigation and potential clinical applications of AhNSCs for treating SCI and related neurological disorders.

Keywords: Biodistribution; Neural Stem Cell; Spinal cord injury; Therapeutic effect; Toxicity; Tumorigenic potential.

Graphical abstract

Fig. 1

Scheme of in vivo preclinical tests. (A) Experiment scheme of preclinical efficacy test. (B) Experiment scheme of preclinical distribution test. (C) Experiment scheme of preclinical general toxicity test. (D) Experiment scheme of preclinical tumorigenicity test. FOB, functional observational battery; MA, motor activity; WPT, weeks post-transplantation.

Fig. 2

Preclinical therapeutic effects of AhNSCs in SCI. (A) Experimental groups and their conditions were summarized. (B) The BBB scores were evaluated weekly until 6 weeks after intrathecal transplantation of AhNSCs. (C) The motor function was evaluated by the Rotarod test weekly until 6 weeks after intrathecal transplantation of AhNSCs. (D) The sensory function was assessed by the Von Frey test weekly until 6 weeks after intrathecal transplantation of AhNSCs. (E) Tissue loss was measured histologically at 6 weeks after intrathecal transplantation of AhNSCs. The red boxes represent spinal cords, and the yellow lines indicate the areas of tissue loss. (F) The percentage of the tissue loss areas in the spinal cords was calculated and compared. * , P < 0.05, compared with the vehicle group; #, P < 0.05, compared with the vehicle group.

Fig. 3

Distribution of AhNSCs in preclinical SCI models. (A, B) Experimental groups, their conditions, and tissues examined were summarized. (C) The amount of human Alu DNA was detected in the 100 ng of gDNA from each organ in each rat by quantitative RT-PCR. (D) Numbers of rats that had human Alu DNA were calculated for each organ.

Fig. 4

Neurobehavioral effects of AhNSCs in preclinical General toxicity study. (A) Experimental groups, their conditions, and tissues examined were summarized. (B, C) Rearing scores in FOB. (D, E) Forelimb (FL) grip strength in FOB. (F, G) Hindlimb (HL) grip strength in FOB. (H, I) Landing Foot Splay in FOB. (J, K) Rectal body temperature in FOB. (L, M) Movement distance in MA.

Fig. 5

In vivo tumorigenicity of AhNSCs. (A) Experimental groups, their conditions, and tissues examined were summarized. (B) After the necropsy, the injection site and the extracted vertebral column were observed. (C) Progressive tumors were confirmed in all animals in the positive control group. (D, E) Body weight was measured to screen the development of tumor.