Human Stem Cells Isolated from Adult Skeletal Muscle Differentiate into Neural Phenotypes

Multipotent neural stem cells have been isolated from the adult [Kirschenbaum B, Nedergaard M, Preuss A, Barami K, Fraser RA, Goldman SA. In vitro neuronal production and differentiation by precursor cells derived from the adult human forebrain. Cereb Cortex 1994;4(6):576-89; Laywell ED, Kukekov VG, Steindler DA. Multipotent neurospheres can be derived from forebrain subependymal zone and spinal cord of adult mice after protracted postmortem intervals. Exp Neurol 1999;156:430-3; Pluchino S, Quattrini A, Brambilla E, Gritti A, Salani G, Dina G, et al. Injection of adult neurospheres induces recovery in a chronic model of multiple sclerosis. Nature 2003;422:688-94] and embryonic [Vescovi AL, Parati EA, Gritti A, Poulin P, Ferrario M, Wanke E, et al. Isolation and cloning of multipotential stem cells from the embryonic human CNS and establishment of transplantable human neural stem cell lines by epigenetic stimulation. Exp Neurol 1999;156:71-83] central nervous system (CNS). In addition, neural cells can be obtained from sources other than the CNS by differentiating stem cells from a non-neural source down a neural lineage. This has previously been performed with pluripotent embryonic stem cells and adult stem cells derived from rat bone marrow [Woodbury D, Schwarz EJ, Prockop DJ, Black IB. Adult rat and human bone marrow stromal cells differentiate into neurons. J Neurosci Res 2000;61:364-70; Woodbury D, Reynolds K, Black IB. Adult bone marrow stromal stem cells express germline, ectodermal, endodermal, and mesodermal genes prior to neurogenesis. J Neurosci 2002;69(6):908-17] and skeletal muscle [Romero-Ramos M, Vourc'h P, Young HE, Lucas PA, Wu Y, Chivatakarn O, et al. Neuronal differentiation of stem cells isolated from adult muscle. J Neurosci Res 2002;69:894-907]. Previously, we have isolated adult stem cells from human skeletal muscle with the potential to differentiate into mesoderm, ectoderm, and endoderm. The following in vitro experiments were designed to determine whether human adult stem cells behaved similarly to rat adult stem cells when both were isolated from skeletal muscle by the same procedure [Romero-Ramos M, Vourc'h P, Young HE, Lucas PA, Wu Y, Chivatakarn O, et al. Neuronal differentiation of stem cells isolated from adult muscle. J Neurosci Res 2002;69:894-907] and subjected to the same protocols to induce neurogenesis. The neural phenotypes that were created through the neurococktail or neurosphere protocol were analyzed for neural characteristics through morphology and immunohistochemistry antibody labeling for proteins to neurons (RT-97, beta-tubulin III, NF-160, NF-200, and synapsin), oligodendrocytes (CNPase and RIP), and astrocytes (GFAP). A calcium uptake assay also showed response to the neuronal excitotoxic agent glutamic acid. In conclusion, the neural differentiated stem cells derived from adult skeletal muscle may be a less invasive alternative for the treatment of CNS disorders over CNS derived neural stem cells.