Optimal Preclinical Conditions for Using Adult Human Multipotent Neural Cells in the Treatment of Spinal Cord Injury

Abstract

Stem cell-based therapeutics are amongst the most promising next-generation therapeutic approaches for the treatment of spinal cord injury (SCI), as they may promote the repair or regeneration of damaged spinal cord tissues. However, preclinical optimization should be performed before clinical application to guarantee safety and therapeutic effect. Here, we investigated the optimal injection route and dose for adult human multipotent neural cells (ahMNCs) from patients with hemorrhagic stroke using an SCI animal model. ahMNCs demonstrate several characteristics associated with neural stem cells (NSCs), including the expression of NSC-specific markers, self-renewal, and multi neural cell lineage differentiation potential. When ahMNCs were transplanted into the lateral ventricle of the SCI animal model, they specifically migrated within 24 h of injection to the damaged spinal cord, where they survived for at least 5 weeks after injection. Although ahMNC transplantation promoted significant locomotor recovery, the injection dose was shown to influence treatment outcomes, with a 1 × 106 (medium) dose of ahMNCs producing significantly better functional recovery than a 3 × 105 (low) dose. There was no significant gain in effect with the 3 × 106 ahMNCs dose. Histological analysis suggested that ahMNCs exert their effects by modulating glial scar formation, neuroprotection, and/or angiogenesis. These data indicate that ahMNCs from patients with hemorrhagic stroke could be used to develop stem cell therapies for SCI and that the indirect injection route could be clinically relevant. Moreover, the optimal transplantation dose of ahMNCs defined in this preclinical study might be helpful in calculating its optimal injection dose for patients with SCI in the future.

Effects of Long-Term In Vitro Expansion on Genetic Stability and Tumor Formation Capacity of Stem Cells

“…AhMNCs show the essential characteristics of NSCs such as expression of NSC-specific markers (Sox2, Nestin, and CD133), self-renewal potential, and differentiation capacity into functional neural cells (neurons and astrocytes) [12,13]. Moreover, we confirmed their therapeutic effects against various CNS disease such as ischemic stroke [12], spinal cord injury [13,14], and multiple sclerosis [15], and developed sensitive experimental methods to monitor the tumorigenic potential of ahMNCs [5]. Since ahMNCs are derived from adult brain tissue, the cells were designated as ahMNCs to be distinguished from NSCs from other sources [12].…”

“…Compared with MSCs, ahMNCs have comparable immunogenicity and even immunosuppressive properties (data not shown). Moreover, in our previous reports [13,14], when ahMNCs were transplanted into the CNS of animal models of spinal cord injury, they were detected until 6 weeks after injection. Therefore, low in vivo tumorigenic potential of long-term cultured ahM-NCs might not originate from immunological rejection.…”

“…Differentiation was conducted following a published procedure [12][13][14] with a slight modification. Briefly, cells were cultured to be 80% confluent in 96-well plate and the medium was replaced by differentiation medium consisting of DMEM/F12, 0.5% FBS, B27, 0.5 mM 3-isobutyl-1-methylxanthine (IBMX, Sigma), and 1% penicillin/streptomycin.…”

Elucidating the Pivotal Neuroimmunomodulation of Stem Cells in Spinal Cord Injury Repair

“…NSCs from the spinal cord also require a distinctive mitogen in vitro , fibroblast growth factor-2 (FGF2) ( Table 1 ) instead of epidermal growth factor (EGF) utilized for NSCs from the brain [ 55 ]. Human NSCs were cultured as neurospheres survived, migrated, and secreted differentiation markers for neurons and oligodendrocytes ( Table 1 ) after long-term transplantation in SCI [ 59 , 60 ]. Transplantation embryonic NSCs in aged mice were capable of improving functional recovery after SCI via the reformation of the cord microenvironment by stimulating the local secretion of growth factors, particularly the hepatocyte growth factor (HGF) ( Table 1 ) [ 61 ].…”

Concepts of Regeneration for Spinal Diseases in 2021

“…Won JS et al [11] investigated in a rat spinal cord injury model the optimal injection route and dose for adult human multipotent neural cells (ahMNCs) from patients with hemorrhagic stroke. Within 24-h migration to the spinal cord lesion, over 5-week survival of lateral ventricle-transplanted ahMNCs were found.…”