Regenerative Stem Cell Therapy for Neurodegenerative Diseases: An Overview

Abstract

Neurodegenerative diseases resulting from the progressive loss of structure and/or function of neurons contribute to different paralysis degrees and loss of cognition and sensation. The lack of successful curative therapies for neurodegenerative disorders leads to a considerable burden on society and a high economic impact. Over the past 20 years, regenerative cell therapy, also known as stem cell therapy, has provided an excellent opportunity to investigate potentially powerful innovative strategies for treating neurodegenerative diseases. This is due to stem cells' capability to repair injured neuronal tissue by replacing the damaged or lost cells with differentiated cells, providing a conducive environment that is in favor of regeneration, or protecting the existing healthy neurons and glial cells from further damage. Thus, in this review, the various types of stem cells, the current knowledge of stem-cell-based therapies in neurodegenerative diseases, and the recent advances in this field are summarized. Indeed, a better understanding and further studies of stem cell technologies cause progress into realistic and efficacious treatments of neurodegenerative disorders.

Keywords: Alzheimer’s disease; Huntington’s disease; Parkinson’s disease; amyotrophic lateral sclerosis; neurodegenerative diseases; regenerative; stem cells; therapy.

Figure 1

Classification of stem cells: ESCs—embryonic stem cells, hiPSCs—human induced pluripotent stem cells, NSCs—neural stem cells, HSCs—hematopoietic stem cells, MSCs—mesenchymal stem cells, ISCs—intestinal stem cells.

Figure 2

Representative diagram depicting the main types of stem cells and their potential to differentiate into various lineages.

Figure 3

Neurodegenerative disease modeling of hiPSCs and ESCs. These cells can be differentiated into neuronal progenitor (NPCs) and MSCs, from which brain cells, such as oligodendrocytes, astrocytes, and different neuronal and glial lineages, can be generated. Note also that the trophic action of MSCs, including the secretion of growth and neurotrophic factors, can act as a coadjuvant to nervous tissue regeneration by promoting angiogenesis, neurogenesis, and immunomodulation. AD: Alzheimer’s disease, ALS: amyotrophic lateral sclerosis, HD: Huntington’s disease, PD: Parkinson’s disease; BDNF: brain-derived neurotrophic factor, bFGF: basic fibroblast growth factor, IGF-1: insulin-like growth factor 1, GDNF: glial-derived neurotrophic factor, VEGF: vascular endothelial growth factor.