Therapeutic benefit of intracerebral transplantation of bone marrow stromal cells after cerebral ischemia in rats
Introduction
Intracerebrally transplanted embryonic mesencephalic precursors have been shown to provide therapeutic benefit in Parkinsonian rats [1]. Embryonic cells can differentiate into various phenotypes when placed in different regions of the brain, suggesting a key role for the host-derived signals in directing differentiation [2], [3]. Grafted fetal tissue establishes extensive interconnections with the host when grafted into homologous regions of adult animals following cerebral ischemic infarction [4], [5]. Although transplantation is a promising treatment for neurodegeneration [6], [7], brain injury and brain ischemia [8], [9], its clinical use is restricted, because of ethical and logistical problems. Therefore, alternatives are being sought to human fetal tissue, and consideration is being given to bone marrow (BM) cells as a source for cell transplantation therapy [10], [11].
Adult BM contains stem and progenitor cells, which have multiple differentiation potentials [12]. BM contains marrow stromal cells (MSCs) [12], capable of differentiating into various cell types [13]. MSCs are chiefly regarded as hematopoietic support cells, and these marrow stromal cells appear to be a source for continual renewal of cells in a number of non-hematopoietic tissues [12]. Adult rat and human BM stromal cells can differentiate into neurons in vitro [14]. MSCs can be induced to differentiate into astrocytes, microglia and macroglia in the brain of adult mice [10], [15], [16], and MSCs differentiate into osteoblasts, chondrocytes and adipocytes [17] when placed into different microenvironments. MSCs migrate throughout forebrain and cerebellum, and they differentiate into astrocytes and neurons after injection into neonatal mouse brain [18]. Collectively, these results have led to the hypothesis that MSCs are capable of differentiating along multiple cell lineages, and hence they represent multipotent stem like cells for nonlymphohematopoietic tissues [19]. MSCs have been used as vehicles for both cell therapy and gene therapy [20], [21].
Neurotrophic factors have well established roles in neuronal development and adult synaptic plasticity, and culture. Nerve growth factor (NGF) is a well-characterized neurotrophic polypeptide for the survival, development, and function of basal forebrain cholinergic neurons in the central nervous system [22]. Administration of NGF by ex vivo gene transfer and grafting of neural stem cells reduces death of striatal projection neurons caused by transient focal ischemia [23], and NGF protects CA1–CA2 hippocampal neurons from ischemic damage by implantation of genetically engineered cells producing NGF [24]. NGF regulates synthesis of acetylcholine and promotes the differentiation and survival of cultured cholinergic neurons [25].
In the present study, we have two primary aims. Using a model of middle cerebral artery occlusion (MCAo) in rats, we test whether multipotential marrow stromal cells from BM transplanted into ischemic brain: (1) survive and express neural phenotypic proteins in an ischemic brain microenvironment; (2) reduce behavioral and functional deficits associated with cerebral infarction. As a secondary aim, we also test the hypothesis that MSCs cultured in NGF confers additional therapeutic benefit.
Section snippets
Animal MCAo model
Adult male Wistar rats (n=24) weighing 270–300 g were employed in all our experiments. Briefly, rats were initially anesthetized with 3.5% halothane and maintained with 1.0–2.0% halothane in 70% N2O and 30% O2 using a face mask. Rectal temperature was maintained at 37 °C throughout the surgical procedure using a feedback-regulated water heating system. We induced transient MCAo using a method of intraluminal vascular occlusion modified in our laboratory [26]. The right common carotid artery,
Results
Ischemic severity was balanced among groups with p-values of >0.47. Rats treated with MSC or MSC+NGF had significant improvement on NSS at 14 days compared to control animals (p<0.05, Fig. 1). No difference in means on NSS between MSC-treated and MSC+NGF treated groups (p=0.45) were detected at 14 days after MCAo.
The treatment of MSC or MSC+NGF significantly improved functional recovery on somatosensory adhesive-removal test (p<0.05). Motor deficit was significantly reduced in animals treated
Discussion
We have demonstrated that MSCs transplanted into the ischemic boundary zone of an ischemic lesion, survive, differentiate into phenotypic neural cells and yield improved functional recovery from stroke.
MSCs from BM survive and express neural phenotypic proteins when grafted into the ischemic brain microenvironment. The observation is consistent with others [44], [18] that grafted BM cells can adopt neural cell fate when exposed to the brain microenvironment and may differentiate into microglia,
Acknowledgements
The authors wish to thank Cecylia Powers, Cynthia Roberts and Xiuli Zhang for technical assistance, and Deb Jewell for secretarial support. This work was supported by NINDS grants PO1 NS23393 and RO1 NS35504.
References (63)
- et al.
Multipotent neural cell lines can engraft and participate in development of mouse cerebellum
Cell
(1992) - et al.
Conditionally immortalized neural progenitor cells grafted to the striatum exhibit site-specific neuronal differentiation and establish connections with the host globus pallidus
Neurobiol. Dis.
(1996) - et al.
Fetal neocortical grafts implanted in adult hypertensive rats with cortical infarcts following a middle cerebral artery occlusion: ingrowth of afferent fibers from the host brain
Exp. Neurol.
(1992) - et al.
Transplantation of fetal neocortex ameliorates sensorimotor and locomotor deficits following neonatal ischemic–hypoxic brain injury in rats
Exp. Neurol.
(1997) - et al.
Intracerebral transplantation of bone marrow with BDNF after MCAo in rat
Neuropharmacology
(2000) - et al.
Cholinergic denervation of the rat hippocampus by fimbrial transection leads to a transient accumulation of nerve growth factor (NGF) without change in mRNANGF content
Neurosci. Lett.
(1986) Nerve growth factor synthesis and nerve growth factor receptor expression in neural development
Int. Rev. Cytol.
(1991)- et al.
GABA receptor agonist promotes reformation of the striatonigral pathway by transplant derived from fetal striatal primordia in the lesioned striatum
Exp. Neurol.
(1997) - et al.
Recovery of function after brain damage: severe and chronic disruption by diazepam
Brain Res.
(1986) - et al.
Seizures and recovery from experimental brain damage
Exp. Neurol.
(1988)