title: Assessment of neuroprotective effects of human umbilical cord blood mononuclear cell subpopulations in vitro and in vivo.
abstract: Experimental transplantation of human umbilical cord blood (hUCB) mononuclear cells (MNCs) in rodent stroke models revealed the therapeutic potential of these cells. However, effective cells within the heterogeneous MNC population and their modes of action are still under discussion.  MNCs and MNC fractions enriched (CD34(+)) or depleted (CD34(-)) for CD34-expressing stem/progenitor cells were isolated from hUCB. Cells were transplanted intravenously following middle cerebral artery occlusion in spontaneously hypertensive rats and directly or indirectly  cocultivated with hippocampal slices previously subjected to oxygen and glucose deprivation. Application of saline solution or a human T-cell line served as controls. In vivo, MNCs, CD34(+) and CD34(-) cells reduced neurofunctional deficits and diminished lesion volume  as determined by magnetic resonance imaging. MNCs were superior to other fractions. However, human cells could not be identified in brain tissue 29 days after stroke induction. Following direct application on postischemic hippocampal slices, MNCs reduced neural damage throughout a 3-day observation  period. CD34(+) cells provided transient protection for 2 days. The CD34(-) fraction, in contrast to in vivo results, failed to reduce neural damage. Direct cocultivation of MNCs was superior to indirect cocultivation of equal cell numbers. Indirect application of up  to 10-fold MNC concentrations enhanced neuroprotection to a level comparable to direct cocultivation. After direct application, MNCs migrated into the slices. Flow cytometric analysis of migrated cells revealed that the CD34(+) cells within MNCs were preferably attracted by damaged  hippocampal tissue. Our study suggests that MNCs provide the most prominent neuroprotective effect, with CD34(+) cells seeming to be particularly involved in the protective action of MNCs. CD34(+) cells preferentially home to neural tissue in vitro, but are not superior concerning  the overall effect, implying that there is another, still undiscovered, protective cell population. Furthermore, MNCs did not survive in the ischemic brain for longer periods without immunosuppression.
authors.affiliation: Fraunhofer Institute for Cell Therapy and Immunology, Leipzig, Germany. johannes.boltze@izi.fraunhofer.de
authors.forename: Johannes
authors.initials: J
authors.lastname: Boltze
authors.forename: Doreen M
authors.initials: DM
authors.lastname: Reich
authors.forename: Susann
authors.initials: S
authors.lastname: Hau
authors.forename: Klaus G
authors.initials: KG
authors.lastname: Reymann
authors.forename: Maria
authors.initials: M
authors.lastname: Strassburger
authors.forename: Donald
authors.initials: D
authors.lastname: Lobsien
authors.forename: Daniel-Christoph
authors.initials: DC
authors.lastname: Wagner
authors.forename: Manja
authors.initials: M
authors.lastname: Kamprad
authors.forename: Tobias
authors.initials: T
authors.lastname: Stahl
mesh_terms: D000818:Animals; D018952:Antigens, CD34 / Q000378:metabolism; D002478:Cells, Cultured; D005312:Fetal Blood / Q000166:cytology*; D006801:Humans; D066298:In Vitro Techniques; D008279:Magnetic Resonance Imaging; D008297:Male; D009414:Nerve Growth Factors; D051381:Rats; D011918:Rats, Inbred SHR; D020521:Stroke / Q000628:therapy*
chemical_list: D018952:Antigens, CD34; D009414:Nerve Growth Factors