title: Characterization of ectopic colonies that form in widespread areas of the nervous system with neural stem cell transplants into the site of a severe spinal cord injury.
abstract: We reported previously the formation of ectopic colonies in widespread areas of the nervous system after transplantation of fetal neural stem cells (NSCs) into spinal cord transection sites. Here, we characterize the incidence, distribution, and cellular composition of the colonies. NSCs harvested from E14 spinal cords from rats that express GFP were treated with a growth factor cocktail and grafted into the site of a complete spinal cord transection. Two months after transplant, spinal cord and brain tissue were analyzed histologically. Ectopic colonies were found at long distances from the transplant in the central canal of the spinal cord, the surface of the brainstem and spinal cord, and in the fourth ventricle. Colonies were present in 50% of the rats, and most rats had multiple colonies. Axons extended from the colonies into the host CNS. Colonies were strongly positive for nestin, a marker for neural precursors, and contained NeuN-positive cells with processes resembling dendrites, GFAP-positive astrocytes, APC/CC1-positive oligodendrocytes, and Ki-67-positive cells, indicating ongoing proliferation. Stereological analyses revealed an estimated 21,818 cells in a colony in the fourth ventricle, of which 1005 (5%) were Ki-67 positive. Immunostaining for synaptic markers (synaptophysin and VGluT-1) revealed large numbers of synaptophysin-positive puncta within the colonies but fewer VGluT-1 puncta. Continuing expansion of NSC-derived cell masses in confined spaces in the spinal cord and brain could produce symptoms attributable to compression of nearby tissue. It remains to be determined whether other cell types with self-renewing potential can also form colonies.
authors.affiliation: Reeve-Irvine Research Center, Departments of Anatomy and Neurobiology, Neurobiology and Behavior, and Neurosurgery, University of California at Irvine School of Medicine, Irvine, California 92697-4265 osteward@uci.edu.
authors.forename: Oswald
authors.initials: O
authors.lastname: Steward
authors.affiliation: Reeve-Irvine Research Center.
authors.forename: Kelli G
authors.initials: KG
authors.lastname: Sharp
authors.affiliation: Reeve-Irvine Research Center.
authors.forename: Kelly Matsudaira
authors.initials: KM
authors.lastname: Yee
authors.affiliation: Reeve-Irvine Research Center.
authors.forename: Maya N
authors.initials: MN
authors.lastname: Hatch
authors.affiliation: Reeve-Irvine Research Center.
authors.forename: Joseph F
authors.initials: JF
authors.lastname: Bonner
mesh_terms: D000818:Animals; D002828:Choristoma; D005260:Female; D009420:Nervous System / Q000473:pathology; D058953:Neural Stem Cells / Q000637:transplantation*; D011247:Pregnancy; D051381:Rats; D011916:Rats, Inbred F344; D012720:Severity of Illness Index; D013119:Spinal Cord Injuries / Q000473:pathology / Q000628:therapy*; D033581:Stem Cell Transplantation / Q000379:methods*
keywords: growth factors; neural stem cells; spinal cord injury; stereology