Incorporation of embryonic CA3 cell grafts into the adult hippocampus at 4-months after injury: Effects of combined neurotrophic supplementation and caspase inhibition

• Published in: Neuroscience Vol. 139; no. 4; pp. 1369 - 1383
• Main Authors: Hattiangady, B., Rao, M.S., Zaman, V., Shetty, A.K.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 2006; Elsevier
• Subjects: Animals; Biological and medical sciences; Brain Injuries - chemically induced; Brain Injuries - surgery; brain injury; brain-derived neurotrophic factor; Bromodeoxyuridine; Caspases - metabolism; Cell Count - methods; Cell Survival; Embryo, Mammalian; Enzyme Inhibitors - pharmacology; Excitatory Amino Acid Agonists - toxicity; fibroblast growth; Fundamental and applied biological sciences. Psychology; graft integration; Headache. Facial pains. Syncopes. Epilepsia. Intracranial hypertension. Brain oedema. Cerebral palsy; Hippocampus - cytology; Histocytochemistry - methods; Kainic Acid - toxicity; Male; Medical sciences; Nerve Growth Factors - pharmacology; Nervous system (semeiology, syndromes); Neurology; Neurons - drug effects; Neurons - physiology; neurotrophin-3; Phosphopyruvate Hydratase - metabolism; Rats; Rats, Inbred F344; Stem Cell Transplantation - methods; temporal lobe epilepsy; Vertebrates: nervous system and sense organs; Ac-YVAD-cmk; temporal lobe epilepsy; TBS; BDNF; CI; NT-3; E19; L; TLE; AP; FGF-2; brain injury; DMEM+F12; DSGL; NeuN; graft integration; KA; V; brain-derived neurotrophic factor; fibroblast growth; neurotrophin-3; BrdU; Embryo; Growth; Cysteine endopeptidases; Epilepsy; Central nervous system; Graft; Brain derived neurotrophic factor; Temporal lobe; Nervous system diseases; neurotrophin 3; Enzyme; Caspase; Cerebral disorder; Peptidases; Central nervous system disease; Hydrolases; Lesion; Fibroblast; Hippocampus
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/j.neuroscience.2006.01.058

As receptivity of the injured hippocampus to cell grafts decreases with time after injury, strategies that improve graft integration are necessary for graft-mediated treatment of chronic neurodegenerative conditions such as temporal lobe epilepsy. We ascertained the efficacy of two distinct graft-augmentation strategies for improving the survival of embryonic day 19 hippocampal CA3 cell grafts placed into the adult hippocampus at 4-months after kainic acid induced injury. The donor cells were labeled with 5′-bromodeoxyuridine, and pre-treated and grafted with either brain-derived neurotrophic factor, neurotrophin-3 and a caspase inhibitor or fibroblast growth factor and caspase inhibitor. The yield of surviving grafted cells and neurons were quantified at 2-months post-grafting. The yield of surviving cells was substantially greater in grafts treated with brain-derived neurotrophic factor, neurotrophin-3 and caspase inhibitor (84%) or fibroblast growth factor and caspase inhibitor (99% of injected cells) than standard cell grafts (26%). Because ∼85% of surviving grafted cells were neurons, increased yield in augmented groups reflects enhanced survival of grafted neurons. Evaluation of the mossy fiber synaptic re-organization in additional kainic acid-lesioned rats receiving grafts enriched with brain-derived neurotrophic factor, neurotrophin-3 and caspase inhibitor at 3-months post-grafting revealed reduced aberrant dentate mossy fiber sprouting in the dentate supragranular layer than “lesion-only” rats at 4 months post-kainic acid, suggesting that some of the aberrantly sprouted mossy fibers in the dentate supragranular layer withdraw when apt target cells (i.e. grafted neurons) become available in their vicinity. Thus, the yield of surviving neurons from CA3 cell grafts placed into the adult hippocampus at an extended time-point after injury could be enhanced through apt neurotrophic supplementation and caspase inhibition. Apt grafting is also efficacious for reversing some of the abnormal synaptic reorganization prevalent in the hippocampus at later time-points after injury.