RESUMO
Foetal onset hydrocephalus is a disease starting early in embryonic life; in many cases it results from a cell junction pathology of neural stem (NSC) and neural progenitor (NPC) cells forming the ventricular zone (VZ) and sub-ventricular zone (SVZ) of the developing brain. This pathology results in disassembling of VZ and loss of NSC/NPC, a phenomenon known as VZ disruption. At the cerebral aqueduct, VZ disruption triggers hydrocephalus while in the telencephalon, it results in abnormal neurogenesis. This may explain why derivative surgery does not cure hydrocephalus. NSC grafting appears as a therapeutic opportunity. The present investigation was designed to find out whether this is a likely possibility. HTx rats develop hereditary hydrocephalus; 30-40% of newborns are hydrocephalic (hyHTx) while their littermates are not (nHTx). NSC/NPC from the VZ/SVZ of nHTx rats were cultured into neurospheres that were then grafted into a lateral ventricle of 1-, 2- or 7-day-old hyHTx. Once in the cerebrospinal fluid, neurospheres disassembled and the freed NSC homed at the areas of VZ disruption. A population of homed cells generated new multiciliated ependyma at the sites where the ependyma was missing due to the inherited pathology. Another population of NSC homed at the disrupted VZ differentiated into ßIII-tubulin+ spherical cells likely corresponding to neuroblasts that progressed into the parenchyma. The final fate of these cells could not be established due to the protocol used to label the grafted cells. The functional outcomes of NSC grafting in hydrocephalus remain open. The present study establishes an experimental paradigm of NSC/NPC therapy of foetal onset hydrocephalus, at the etiologic level that needs to be further explored with more analytical methodologies.
Assuntos
Hidrocefalia/terapia , Células-Tronco Neurais/transplante , Animais , Diferenciação Celular , Proliferação de Células , Neurogênese , RatosRESUMO
Fetal onset hydrocephalus and abnormal neurogenesis are two inseparable phenomena turned on by a cell junction pathology first affecting neural stem/progenitor cells (NSPCs) and later the multiciliated ependyma. The neurological impairment of children born with hydrocephalus is not reverted by derivative surgery. NSPCs and neurosphere (NE) grafting into the cerebrospinal fluid (CSF) of hydrocephalic fetuses thus appears as a promising therapeutic procedure. There is little information about the cell lineages actually forming the NE as they grow throughout their days in vitro (DIV). Furthermore, there is no information on how good a host the CSF is for grafted NE. Here, we use the HTx rat, a model with hereditary hydrocephalus, with the mutation expressed in about 30% of the litter (hyHTx), while the littermates develop normally (nHTx). The investigation was designed (i) to establish the nature of the cells forming 4 and 6-DIV NE grown from NSPCs collected from PN1/nHTx rats and (ii) to study the effects on these NEs of CSF collected from nHTx and hyHTx. Immunofluorescence analyses showed that 90% of cells forming 4-DIV NEs were non-committed multipotential NSPCs, while in 6-DIV NE, 40% of the NSPCs were already committed into neuronal, glial and ependymal lineages. Six-DIV NE further cultured for 3 weeks in the presence of fetal bovine serum, CSF from nHTx or CSF from hyHTx, differentiated into neurons, astrocytes and ßIV-tubulin+ multiciliated ependymal cells that were joined together by adherent junctions and displayed synchronized cilia beating. This supports the possibility that ependymal cells are born from subpopulations of NSC with their own time table of differentiation. As a whole, the findings indicate that the CSF is a supportive medium to host NE and that NE grafted into the CSF have the potential to produce neurons, glia and ependyma.
Assuntos
Astrócitos/citologia , Líquido Cefalorraquidiano/fisiologia , Epêndima/citologia , Células Ependimogliais/citologia , Hidrocefalia/patologia , Células-Tronco Neurais/metabolismo , Animais , Diferenciação Celular , Proliferação de Células , Cílios/metabolismo , Modelos Animais de Doenças , Humanos , Células-Tronco Multipotentes/citologia , Células-Tronco Multipotentes/metabolismo , Células-Tronco Neurais/citologia , Neurônios/citologia , RatosRESUMO
Fetal-onset hydrocephalus is not only a disorder of cerebrospinal fluid (CSF) dynamics, but also a brain disorder. How can we explain the inborn and, so far, irreparable neurological impairment in children born with hydrocephalus? We hypothesize that a cell junction pathology of neural stem cells (NSC) leads to two inseparable phenomena: hydrocephalus and abnormal neurogenesis. All neurons, glial cells, and ependymal cells of the mammalian central nervous system originate from the NSC forming the ventricular zone (VZ) and the neural progenitor cells (NPC) forming the subventricular zone. Several genetic mutations and certain foreign signals all convey into a final common pathway leading to cell junction pathology of NSC and VZ disruption. VZ disruption follows a temporal and spatial pattern; it leads to aqueduct obliteration and hydrocephalus in the cerebral aqueduct, while it results in abnormal neurogenesis in the telencephalon. The disrupted NSC and NPC are released into the CSF and may transform into neurospheres displaying a junctional pathology similar to that of NSC of the disrupted VZ. These cells can then be utilized to investigate molecular alterations underlying the disease and open an avenue into possible NSC therapy.