Early Response of Endogenous Adult Neural Progenitor Cells to Acute Spinal Cord - 《stemcells》干细胞学杂志干细胞之家



免疫细胞治疗专区	欢迎关注干细胞微信公众号

12 3 4 5 6 7 8 9 10 ... 27 下一页

返回列表

查看: 516266\|回复: 267	go Early Response of Endogenous Adult Neural Progenitor Cells to Acute Spinal Cord [复制链接]

江边孤钓

版主

Rank: 7 Rank: 7 Rank: 7

积分: 0
威望: 0
包包: 483

楼主

发表于 2009-3-5 00:07 |只看该作者 |倒序浏览 |打印

作者：Yan Kea,b, Liying Chia, Renshi Xua, Chun Luoa, David Gozalb, Rugao Liua作者单位：a Department of Anatomy and Cell Biology, University of North Dakota School of Medicine, Grand Forks, North Dakota, USA;b Kosair Childrens Hospital Research Institute, Department of Pediatrics, University of Louisville, Louisville, Kentucky, USA + {' U7 A6 S" W# d% e/ a0 ~
   1 A) [$ [  n8 o8 d

      , b- w. y* F0 k: \' c

         0 Z% U/ `7 V, i+ i8 p; N

         ) L+ B# x! p% m
         6 f6 T- H# F3 P9 u4 r# d


      6 g% i0 \1 N5 ?5 Q
      ; n( U5 b5 O9 L' Y
      【摘要】5 k! z: S+ x2 `7 O# A; P
   Adult neural progenitor cells (NPCs) are an attractive source for functional replacement in neurodegenerative diseases and traumatic injury to the central nervous system (CNS). It has been shown that transplantation of neural stem cells or NPCs into the lesioned region partially restores CNS function. However, the capacity of endogenous NPCs in replacement of neuronal cell loss and functional recovery of spinal cord injury (SCI) is apparently poor. Furthermore, the temporal and spatial response of endogenous adult NPCs to SCI remains largely undefined. To this end, we have analyzed the early organization, distribution, and potential function of NPCs in response to SCI, using nestin enhancer (promoter) controlled LacZ reporter transgenic mice. We showed that there was an increase of NPC proliferation, migration, and neurogenesis in adult spinal cord after traumatic compression SCI. The proliferation of NPCs detected by 5-bromodeoxyuridine incorporation and LacZ staining was restricted to the ependymal zone (EZ) of the central canal. During acute SCI, NPCs in the EZ of the central canal migrated vigorously toward the dorsal direction, where the compression lesion is generated. The optimal NPC migration occurred in the adjacent region close to the epicenter. More significantly, there was an increased de novo neurogenesis from NPCs 24 hours after SCI. The enhanced proliferation, migration, and neurogenesis of (from) endogenous NPCs in the adult spinal cord in response to SCI suggest a potential role for NPCs in attempting to restore SCI-mediated neuronal dysfunction. 1 N8 [0 \4 l1 j  ~+ B  N, g2 A
      【关键词】 Neural progenitor cells Neurogenesis Spinal cord injury Nestin Radial glia
   INTRODUCTION
( h" u- L0 S: ?" N7 W
Traumatic spinal cord injury (SCI) causes neuronal and glial cell damage and tissue disruption, leading to neurological dysfunction. Two major pathological stages occur in SCI: The primary injury involves mechanical force¨Cmediated tissue damage and cell necrosis, and the secondary injury results in a cascade of biochemical events that produce progressive destruction on the spinal cord tissues . Taken together, the transplantation of a variety of cells, particularly the neural stem cells or NPCs, in multiple central nervous system (CNS) injury paradigms has provided to a certain degree encouraging results for functional recovery./ F, C8 R! `. u, Y

The presence of NPCs in adult mammalian CNS is now undisputable .

A comprehensive understanding of NPCs responsible for neurogenesis is essential to the development of therapies aiming for functional recovery after SCI. However, the early response of NPCs to SCI and the role of NPCs in neural circuitry recovery in SCI remain largely unknown. Expression of nestin in the CNS is generally considered a reliable NPC marker and has been extensively used for the characterization of NPCs in vitro and in vivo . To this end, we used the nestin second-intron enhancer controlled LacZ transgenic mice to analyze the temporal response of NPCs to SCI. We showed that there is an increased NPC proliferation in the ependymal zone (EZ) of the central canal, an enhanced NPC migration from EZ of the central canal to the lesion regions, and an increased neurogenesis from NPCs after SCI. The increased NPC proliferation, migration, and differentiation suggest that the regenerative NPCs may play an important role in attempting to repair SCI-damaged neural circuitry.
9 w9 [1 f9 ?; `6 N- z% D* ~! G8 ]5 f/ T
MATERIALS AND METHODS
8 r0 r1 @8 @; G7 b
Transgenic Mouse Lines0 m. u$ m& g& x# i' X* c: ~6 D( s

Adult (70¨C80 days of age) nestin second-intron enhancer controlled LacZ reporter transgenic mice (pNes-Tg) (Jackson Laboratory, Bar Harbor, ME, http://www.jax.org) were used for compression SCI . Transgenic progeny were identified by regular polymerase chain reaction amplification of tail DNA using specific primers. The experimental protocols for SCI studies were approved by the Institutional Animal Use and Care Committee of the University of North Dakota and are in close agreement with the National Institutes of Health (NIH) guidelines for the care and use of laboratory animals., C0 {3 s( m0 d! s+ J: m7 @

Compression SCI
3 D% A0 f! i  y
The experimental model for acute mouse compression SCI was essentially similar to that previously described by Farooque . Briefly, animals were deeply anesthetized with pentobarbital in a dose of 20 mg/kg body weight by i.p. approach. After skin decontamination, a 15¨C20-mm midline incision was made, and a laminectomy of T10 to L2 vertebra was performed under a dissection microscope (Model SMZ660: Nikon Corporation, Tokyo, http://www.nikon.com). Animals were then placed in a modified stereotaxic apparatus, and 15 g (mild lesion) to 30 g (severe lesion) of weights was applied to the spinal cord for 5 minutes with a 1 x 2¨Cmm rectangular plastic plate. After injury, skin was sutured and mice were kept under a heating lamp for recovery. Twenty-four hours after SCI, mice were processed for analysis of the response of NPCs to spinal cord lesion.

In Vivo 5-Bromodeoxyuridine Labeling& d4 [8 h5 y* `) u) Q& B& r  G+ F
% e( r0 S$ h* B4 d& h
5-Bromodeoxyuridine (BrdU) at 50 mg/kg per day was administrated by i.p. for 5 days to adult pNes-Tg mice. On day 5 of BrdU administration, mice underwent SCI. Mice were continuously injected with BrdU for 1 or 2 days before the spinal cords were processed for analysis of the early response of NPCs to acute traumatic injury. BrdU immunostaining is described in the following section.

LacZ Staining and Immunohistochemical Staining
' F2 |- a- k: B6 [2 c8 N1 s2 b% [
The lumbar region of the spinal cord was used to analyze the organization and distribution of NPCs in response to SCI. For LacZ staining, sections (12 µm) were incubated in 5-bromo-4-chloro-3-indolyl-ß-D-galactopyranoside (X-gal) solution for 16 hours at room temperature as previously described. For immunohistochemical staining, sections were incubated in blocking buffer (10% goat serum/0.2% Triton X-100 in 1 x phosphate-buffered saline , pH 7.5) for 1 hour at room temperature. Primary antibody (anti-BrdU, anti-NeuN, and anti¨Cglial fibrillary acidic protein; Chemicon International, Temecula, CA, http://www.chemicon.com) was added to the blocking buffer at 1:250 dilutions. The section was then incubated with specific antibody at 4¡ãC overnight. Subsequently, sections were washed five times (5 minutes each) in 1 x PBS (pH 7.5) containing 0.5% Triton X-100, followed by incubation with specific fluorescein-conjugated secondary antibody (Purchased from Jackson ImmunoResearch Laboratories Inc., West Grove, PA, http://www.jacksonimmuno.com) for 2 hours at room temperature. After extensive washes, sections were covered with anti-fade medium and sealed for fluorescent microscopic analysis. For negative control staining, sections were incubated without primary antibody.8 {, d/ `( T; R3 M/ {& f0 z
7 H8 d0 ~9 H0 k
Image Collection and Analysis

All images were collected and analyzed with a Nikon fluorescent microscope E800 (Nikon Corporation, Tokyo, http://www.nikon.com) equipped with the Spot digital camera and Photoshop software (Adobe Systems Incorporated, San Jose, CA, http://www.adobe.com). Quantifications of NPC distribution were performed by counting and analyzing the number of LacZ-positive cells in the dorsal and ventral horn regions. Under severe and moderate injury conditions, cells including NPCs, neurons, and other cell types, and tissues in the epicenter were significantly disrupted due to mechanical damage and inflammatory reactions. For this reason and for experimental consistency, we selected the sections 2 mm caudally from the epicenter and counted the LacZ-positive cells at every fifth section for a total of five sections, and the number of NPCs was averaged (five sections per mouse, three mice per group). Quantifications of LacZ staining intensity and BrdU staining intensity at the EZ surrounding central canal of mouse spinal cords were performed with the NIH software Image J. Similar to the quantification of LacZ-positive cells, five sections per mouse and three mice per group were analyzed. Arbitrary units were used to express the LacZ and BrdU staining intensity of EZ.

Statistical Analysis
7 _* B" {0 e& W) C( C
Statistical analysis of SCI versus normal control was performed using the paired Student¡¯s t test. All data were expressed as average ¡À SD. p 9 q; h' s# J+ F! ]) c

RESULTS

Tissue Damage and Neurological Dysfunction in Acute Compression SCI Mice* `9 V# V% q" S+ H# Z8 f

The acute compression injury mouse model was selected to analyze the early response of NPCs to SCI according to a similar procedure described by Farooque . Mild (15 g of weight for 5 minutes), moderate (20 g of weight for 5 minutes), and severe (30 g of weight for 5 minutes) lesion conditions were applied to generate different degrees of SCI. After acute injury, mouse hind limbs exhibited partial paralysis under mild lesion and exhibited complete paralysis under moderate and severe lesion conditions within 24 ¨C 48 hours. Control mice (no weights applied after laminectomy) had minimal alterations in walking behaviors. The morphological and pathological changes adjacent to the epicenter of the lesioned spinal cords are shown in Figure 1A. There was extensive swelling, hemorrhage, and tissue degeneration in the epicenter as the degree of injury was increased, shown by the hematoxylin & eosin staining. With the different lesion conditions, we carried out studies to analyze the early responses of adult endogenous NPCs to SCI.
; H& O; q( G" ^1 e3 B
Figure 1. SCI promoted early responses of NPCs to tissue damage. (A): SCI generates different degrees of tissue damage analyzed by HE staining. Different injury conditions ¨C SCI(Mi), mild; SCI(Mo), moderate; and SCI(Se), severe ¨C generate different degrees of spinal cord lesions. Scale bar = 1,250 µm. (B): Identification of NPCs in the ependymal zone of the central canal region of adult mouse spinal cord was performed by LacZ staining. Scale bar = 120 µm. (C): SCI significantly increases the number of cells distributed in the central canal region compared with that of surgical control (n = three mice; five sections per mouse; *p
* F- _% f. |) L. Y
Early Responses of NPCs to Compression SCI5 v, Q1 E3 J$ k2 Z# }; `! `  O+ J

Nestin second-intron enhancer controlled reporter gene activity assay revealed that there was increased LacZ staining in the EZ of the central canal region upon SCI (Fig. 1B). The number of NPCs migrating out toward the dorsal direction was dramatically increased in mild, moderate, and severe SCI compared with that of surgical control mice (Fig. 1C). Interestingly, under severe SCI conditions, large aggregates positively stained with LacZ apparently dissociated from the EZ of the central canal region migrated out toward the lesioned region in the dorsal areas (Fig. 1B).* q6 a* [, \( G* M) V
( _/ \; T# x7 d
Proliferation of NPCs in the EZ of the Central Canal
) q9 @3 v4 C$ {3 W# w% c" J
A combination of LacZ staining and BrdU labeling was used to study proliferation of NPCs in the pNes-LacZ mouse model after SCI . We focused on the moderate lesion conditions to analyze the organization and distribution of NPCs to SCI. We found that the EZ of the central canal contains NPCs that are positively stained with LacZ and BrdU antibody. Furthermore, there was an increase of LacZ (Figs. 1B and 2) and BrdU (Fig. 2) staining intensity in the EZ of the central canal of the SCI mice compared with the surgical control mice. Most LacZ-positive NPCs in the EZ of the central canal region were co-localized with BrdU staining, suggesting that there is an increase of NPC proliferation in the EZ of the central canal region upon SCI.- X" O$ P, T) |

Figure 2. SCI increased NPC proliferation in the EZ of the central canal. (A): The representative LacZ staining and BrdU labeling of NPCs in the EZ of the central canal region in the control mouse. Scale bar = 150 µm. (B): The representative LacZ staining and BrdU labeling of NPCs in the EZ of the central canal region in moderate SCI mice, SCI(Mo). Scale bar = 150 µm. (C): The representative confocal images showing the co-localization of LacZ- and BrdU-positive NPCs in the EZ of the central canal region of the control mouse. Scale bar = 80 µm. (D): The representative confocal images showing the co-localization of LacZ- and BrdU-positive NPCs in the EZ of the central canal region of the SCI mouse. Scale bar = 80 µm. (E): SCI significantly increased LacZ staining intensity in the EZ of the central canal compared with surgical controls (n = three mice, five sections/mouse; *p 8 ]5 Y2 F" y. F# d/ S- N1 W& B3 P+ j
0 U, R; I* J, ^6 a: g
On the other hand, most of the LacZ-positive cells outside of the central canal region did not co-localize with BrdU, suggesting that these cells were not proliferative (Fig. 2). However, these cells were highly migratory and could mobilize an immediate response to SCI. The increased number of NPCs in the dorsal horn regions of the SCI mouse spinal cord was largely attributed to the migration of NPCs from the EZ of the central canal region (Fig. 2B).

Migration of NPCs from the EZ of the Central Canal to the Dorsal Direction in the Lesioned Mice Spinal Cords

Both moderate and severe injury paradigms were used to analyze NPC migration in response to SCI. In these experiments, the number of NPCs migrated out from the EZ of the central canal toward the dorsal direction was significantly increased in SCI mice compared with controls (Fig. 3). In addition to the individual NPCs, the large cell aggregates apparently dissociated from the EZ of the central canal also migrated toward the lesion direction under the severe lesion conditions (Figs. 1B and 3C).+ E& B0 v7 t0 ?, w
2 H4 q  ]" Y7 `5 o
Figure 3. Migration of NPCs from the EZ of the central canal to the lesion region of dorsal horn area after SCI. (A): Representative spinal cord images of LacZ staining at different magnifications demonstrating the distribution of NPCs in the EZ of the central canal of the surgical control mice. Only a few of NPCs migrate out from the EZ of the central canal to the dorsal direction. (B): Representative spinal cord images of LacZ staining at different magnifications demonstrating the migration of NPCs from the EZ of the central canal to the dorsal direction in the moderate SCI mice. (C): Representative spinal cord images of LacZ staining at different magnifications demonstrating the migration of NPCs from the EZ of the central canal to the dorsal direction in the severe SCI mice. Scale bars in x4, x10, x20, and x40 images represent 1,200 µm, 300 µm, 200 µm, and 100 µm, respectively. (D): Quantification of NPCs migrating out from the EZ of the central canal to the lesion area (n = three mice, five sections per mouse; *p . t5 b' N% }4 L% h! N: f9 X: ~; }

Distribution and Organization of NPCs in Dorsal and Ventral Horn Regions upon SCI0 S: v6 Y, B( `, D7 k/ [; z
( w5 U1 Y) l5 b  q
To study the early response of NPCs to SCI, we also analyzed the distribution and organization of NPCs in the dorsal and ventral horn regions. LacZ-positive NPCs distributed in all the regions of the adult mouse spinal cord in addition to the EZ of the central canal. There was a polarity distribution of NPCs in the spinal cord. The number of NPCs distributed in the dorsal horn region was far higher than in the ventral horn region of the spinal cord (Figs. 4 and 5). After SCI, the number of NPCs in the dorsal and ventral regions of the spinal cord was significantly increased compared with the specific regions of the control mice (Fig. 4). Quantitative analyses of NPCs in the dorsal, ventral, and central canal regions of the control and SCI mice are shown in Figure 4C. In addition, the detailed distribution of NPCs in the dorsal horn regions is shown in Figure 5.

Figure 4. Distribution of NPCs in the dorsal horn and ventral horn regions of SCI mice compared with surgical control mice. (A): Representative images of LacZ staining demonstrating the distribution of NPCs in the dorsal horn regions of the control and moderate SCI mouse spinal cords. (B): Representative images of LacZ staining demonstrating the distribution of NPCs in the ventral horn regions of the control and moderate SCI mouse spinal cords. Scale bar = 250 µm. (C): Quantification of NPC distribution in the C.C, upper C.C., LDH, and RDH of SCI mice compared with surgical control mice (n = three mice, five sections per mouse; *p

Figure 5. Analysis of the distribution of NPCs in the dorsal horn regions of SCI mice compared with surgical control mice. (A): Representative images of LacZ staining demonstrating the distribution of NPCs in the dorsal horn regions of surgical control mice at x20 and x40 magnifications. Scale bars in the x20 and x40 images represent 300 µm and 200 µm, respectively. (B): Representative images of LacZ staining demonstrating the distribution of NPCs in the dorsal horn regions of moderate SCI mice at x20 and x40 magnifications. Scale bars in the x20 and x40 images represent 300 µm and 200 µm, respectively. Abbreviations: NPC, neural progenitor cell; SCI, spinal cord injury; SCI(Mo), moderate spinal cord injury.

Enhanced Neurogenesis from NPCs in Response to SCI- \! N5 E' s& P. a+ {9 t/ v
/ `! k$ p' C/ G4 v
The increased proliferation of NPCs in the EZ of the central canal and enhanced migration of NPCs to the lesioned regions suggest that NPCs may attempt to repair SCI-mediated damage. To further study the potential functionality of the NPCs in response to SCI, we examined the cellular fate of NPCs adjacent to the lesioned epicenter. There was evidence of increased neurogenesis from NPCs as determined with the neuronal markers NeuN (Fig. 6) and Tuj1 (data not shown). Similarly, assessments of astrogenesis and oligogenesis from NPCs using specific astrocyte and oligodendrocyte markers revealed that, to a large extent, there was no astrogenesis (Fig. 7) and oligogenesis (data not shown) from the NPCs after SCI.% c" o- B$ e+ j1 J
) M2 z/ h. Q6 W5 d- S, ~
Figure 6. Analysis of neurogenesis of NPCs in the spinal cords of SCI mice compared with surgical control mice. (A): Representative images of LacZ and NeuN staining in surgical control mouse spinal cord. Scale bar = 1,200 µm. (B): Representative images of LacZ and NeuN staining in moderate SCI mouse spinal cord. Scale bar = 1,200 µm. (C): Representative images of LacZ and NeuN staining demonstrating the co-localization of NPCs and neurons in the dorsal horn region of the surgical control mouse spinal cord. Scale bar = 35 µm. (D): Representative images of LacZ and NeuN staining demonstrating the co-localization of NPCs and neurons in the dorsal horn region of the moderate SCI mouse spinal cord. Scale bar = 35 µm. (E): The representative confocal images showing the co-localization of LacZ and NeuN in the control mouse spinal cord. Scale bar = 10 µm. (F): The representative confocal images showing the co-localization of LacZ and NeuN in the control mouse spinal cord. Scale bar = 10 µm. (G): Quantification of neurogenesis of NPCs in the spinal cord in response to SCI compared with surgical controls (n = 5; *p

Figure 7. Analyses of astrogenesis of NPCs in the spinal cord of SCI mice compared with surgical controls. (A): Representative images of GFAP and LacZ staining in the C.C. region in the surgical control mouse spinal cord. Scale bar = 100 µm. (B): Representative images of GFAP and LacZ staining in the D.H. region in the surgical control mouse spinal cord. Scale bar = 40 µm. (C): Representative images of GFAP and LacZ staining in the C.C. region in the moderate SCI mouse spinal cord. Scale bar = 100 µm. (D): Representative images of GFAP and LacZ staining in the D.H. region in the moderate SCI mouse spinal cord. Scale bar = 40 µm. No astrogenesis was detected from NPCs in response to SCI. Abbreviations: C.C., central canal; D.H., dorsal horn; GFAP, glial fibrillary acidic protein; NPC, neural progenitor cell; SCI, spinal cord injury; SCI(Mo), moderate spinal cord injury.9 T- H' `. w- V) D9 s
2 K) P& f9 h3 ^- _8 n: j* t
DISCUSSION
( y% V0 K# O, u9 p" l' @  u
Substantial evidence has supported the presence of NPCs in the adult CNS . The present study, using nestin second-intron enhancer controlled reporter transgenic mice (pNes-LacZ) with different lesion conditions, demonstrates three major findings: (a) SCI induces NPC proliferation in the EZ of the central canal of the adult mouse spinal cord, (b) SCI promotes NPC migration from the EZ of the central canal toward the dorsal horn, where the lesion occurs, and (c) SCI increases de novo neurogenesis from NPCs in and adjacent to the lesioned regions. The enhanced proliferation, migration, and neurogenesis of NPCs in response to acute SCI during the early phase suggest that adult endogenous NPCs may be potentially used for functional recovery.
$ G+ V. W+ ^7 R) w1 p3 b
The early response of adult NPCs to traumatic SCI can be divided into three distinct but closely related stages (i.e., NPC proliferation, migration, and differentiation). In light of the findings mentioned above, we have initially identified and characterized one proliferative population of NPCs that was labeled with BrdU and co-localized with LacZ staining in the adult mouse spinal cord after SCI. Notably, the LacZ staining intensity and BrdU staining intensity were increased in the EZ of the central canal region as the degree of injury was increased, compared with the surgical controls. The co-localization of LacZ and BrdU suggests that there is an increase of NPC proliferation in response to SCI (Figs. 1 and 2). The proliferative NPCs identified within 6¨C7 days of BrdU labeling were primarily restricted to the EZ of the central canal region (Fig. 2A, 2B). In addition, SCI promoted migration of NPCs from the EZ of the central canal region to the lesioned dorsal horn area. Interestingly, most of the NPCs distributed outside of the EZ of the central canal were not labeled with BrdU, suggesting that they were not proliferative. The NPCs located outside of the EZ of the central canal tended to migrate toward the lesioned area first. Apparently, the NPCs that migrated out of the central canal lost proliferative ability, given that those NPCs were not labeled with BrdU (Fig. 2).  _2 A2 E* y, p" F6 w, `2 E
; x  v0 n5 D3 Z* l
Compared with control mice, migration of NPCs from the EZ of the central canal toward the lesioned dorsal regions was greatly enhanced in SCI mice. Several findings related to adult NPC proliferation and migration in response to SCI are worth mentioning. First, increased proliferation and migration of NPCs occurred as early as 6 hours after SCI (data not shown), and by 24 hours after SCI, there was a dramatic increase in the number of NPCs in the dorsal horn region (Figs. 4 and 5). Second, the migratory path of NPCs in response to SCI was toward the dorsal horn direction, where the lesion occurred. In contrast, control mice exhibited only a few NPCs that migrated out from the EZ of the central canal. Third, there is a polarity in the NPC distribution within the spinal cord. A large proportion of the NPCs are located in the dorsal horn region (Lamina I, II, and III regions), and only a few NPCs are distributed in the ventral region (Fig. 4). The mechanism(s) underlying the differential organization and distribution of NPCs within the spinal cord remain largely unknown. In response to SCI, there was an increase in the number of NPCs to both dorsal and ventral horn regions (Figs. 4 and 5). From the analysis of the organization and distribution of NPCs, we conclude that the increased number of NPCs in the dorsal and ventral regions originated from the EZ of the central canal. As indicated above, BrdU labeling and LacZ staining confirmed that proliferative NPCs are located primarily in the central canal, whereas the non-proliferative NPCs are distributed unevenly across spinal cord. These findings may have important applications to the functional recovery of SCI damage by stimulating endogenous NPCs for regeneration, because there is an increase of adult NPC organization and distribution in response to SCI.

The current study also provides important insights into the regenerative potential of adult NPCs toward neuronal direction in response to SCI. Our findings showed an increase of neurogenesis, but not astrogenesis or oligogenesis, from endogenous NPCs in the mouse SCI model. Approximately 26% of the endogenous adult NPCs in the dorsal horn region adjacent to the lesioned area differentiated toward neurons by immunohistochemical staining with neuronal markers NeuN (Fig. 6) and Tuj1 (data not shown), respectively. The increased neurogenesis from NPCs in the lesioned spinal cord suggests that the nestin-positive adult NPCs may contribute to neuronal replacement after SCI. The early response of enhanced neuronal differentiation from NPCs in the SCI model supported previous findings that traumatic brain injury and neurodegenerative diseases promoted cortical, hippocampus, and striatum neurogenesis in animal models . Of note, the temporal and spatial responses of endogenous adult NPCs were different from those of transplanted cells after SCI. Thus, current study of the early response (proliferation, migration, and neurogenesis) of endogenous NPCs to SCI may offer a therapeutic potential to enable differentiation of specific population of NPCs toward neuronal lineage which could ultimately promote functional recovery.8 m& J- k0 O1 ~4 N: e6 Q! {
9 V+ Z9 N( L2 Z- T4 @1 q: y- e
ACKNOWLEDGMENTS4 V6 s& P; D. d- V0 s

This study was supported in part by NIH (grants AG23923, NS45829, and HL75034) and the Muscular Dystrophy Association (grant 3334).9 {  X- }$ R- q, K8 `% A. L

DISCLOSURES$ l, R& D7 F2 X& {
6 Q: ~% m  O, g8 k3 i
The authors indicate no potential conflicts of interest.
      【参考文献】
3 q- ^7 o$ H& R" x: N, e9 p- j

Blight AR. Spinal cord injury models: Neurophysiology. J Neurotrauma 1992;9:147¨C149.5 O+ ]+ i" ]* _" E  Q; e' B
0 P6 M+ e3 m$ U2 Q
Blight A. Mechanical factors in experimental spinal cord injury. J Am Paraplegia Soc 1988;11:26¨C34.

Juurlink BH, Paterson PG. Review of oxidative stress in brain and spinal cord injury: Suggestions for pharmacological and nutritional management strategies. J Spinal Cord Med 1998;21:309¨C334.

Anderson DK, Hall ED. Pathophysiology of spinal cord trauma. Ann Emerg Med 1993;22:987¨C992.

Beattie MS, Farooqui AA, Bresnahan JC. Review of current evidence for apoptosis after spinal cord injury. J Neurotrauma 2000;17:915¨C925.
+ Y% ~7 m: y- ?% }$ ~# g/ P
Grossman SD, Rosenberg LJ, Wrathall JR. Temporal-spatial pattern of acute neuronal and glial loss after spinal cord contusion. Exp Neurol 2001;168:273¨C282.
2 |" Y' w: x' r% [
McDonald JW, Liu XZ, Qu Y et al. Transplanted embryonic stem cells survive, differentiate and promote recovery in injured rat spinal cord. Nat Med 1999;5:1410¨C1412.! d5 W; j; t2 h) Q; s

Akiyama Y, Honmou O, Kato T et al. Transplantation of clonal neural precursor cells derived from adult human brain establishes functional peripheral myelin in the rat spinal cord. Exp Neurol 2001;167:27¨C39.# V9 {4 ^  W0 `" s  I

Vroemen M, Aigner L, Winkler J et al. Adult neural progenitor cell grafts survive after acute spinal cord injury and integrate along axonal pathways. Eur J Neurosci 2003;18:743¨C751.

Fujiwara Y, Tanaka N, Ishida O et al. Intravenously injected neural progenitor cells of transgenic rats can migrate to the injured spinal cord and differentiate into neurons, astrocytes and oligodendrocytes. Neurosci Lett 2004;366:287¨C291.) }! s; e. y. V

Hill CE, Proschel C, Noble M et al. Acute transplantation of glial-restricted precursor cells into spinal cord contusion injuries: Survival, differentiation, and effects on lesion environment and axonal regeneration. Exp Neurol 2004;190:289¨C310.% g  j( ?! t. {' @. t4 A- H

Cao QL, Zhang YP, Howard RM et al. Pluripotent stem cells engrafted into the normal or lesioned adult rat spinal cord are restricted to a glial lineage. Exp Neurol 2001;167:48¨C58.6 u7 T+ w% K! Q, v; C
; K" D& ?9 _+ {% G) s8 G
Setoguchi T, Nakashima K, Takizawa T et al. Treatment of spinal cord injury by transplantation of fetal neural precursor cells engineered to express BMP inhibitor. Exp Neurol 2004;189:33¨C44.; o' J. U, c& b1 g. R6 ~3 `7 j

Setoguchi T, Yone K, Matsuoka E et al. Traumatic injury-induced BMP7 expression in the adult rat spinal cord. Brain Res 2001;921:219¨C225.
3 r7 j% @5 g  G
Li Y, Field PM, Raisman G. Repair of adult rat corticospinal tract by transplants of olfactory ensheathing cells. Science 1997;277:2000¨C2002.; Y! A5 Y6 [9 U+ V7 O' c" k
7 _& V9 n) {  O% y, A+ b
Martin D, Robe P, Franzen R et al. Effects of Schwann cell transplantation in a contusion model of rat spinal cord injury. J Neurosci Res 1996;45:588¨C597.

Weiss S, Dunne C, Hewson J et al. Multipotent CNS stem cells are present in the adult mammalian spinal cord and ventricular neuroaxis. J Neurosci 1996;16:7599¨C7609.
' n7 A) m  D* x% f
Clarke D, Frisen J. Differentiation potential of adult stem cells. Curr Opin Genet Dev 2001;11:575¨C580.$ v3 y2 U# ^8 O9 r% e% ^
9 a" E! Y/ |! R. h+ H6 S7 t- _& z6 V
Clarke DL, Johansson CB, Wilbertz J et al. Generalized potential of adult neural stem cells. Science 2000;288:1660¨C1663.
/ I9 X/ o+ e/ {. Y0 ?6 g
Johansson CB, Momma S, Clarke DL et al. Identification of a neural stem cell in the adult mammalian central nervous system. Cell 1999;96: 25¨C34.

Lie DC, Song H, Colamarino SA et al. Neurogenesis in the adult brain: New strategies for central nervous system diseases. Annu Rev Pharmacol Toxicol 2004;44:399¨C421.' T, ^! A6 T! ]% q6 n
. `7 ?  H( D. x/ K. Y
Roy NS, Wang S, Jiang L et al. In vitro neurogenesis by progenitor cells isolated from the adult human hippocampus. Nat Med 2000;6:271¨C277.$ x, E6 p1 }# Z/ T2 H

Bedard A, Parent A. Evidence of newly generated neurons in the human olfactory bulb. Brain Res Dev Brain Res 2004;151:159¨C168./ A* d: d" P- A& }& y
5 t7 z1 U4 P  c7 P
Bernier PJ, Bedard A, Vinet J et al. Newly generated neurons in the amygdala and adjoining cortex of adult primates. Proc Natl Acad Sci U S A 2002;99:11464¨C11469.
' y+ s& g' V9 @6 x8 q3 |% [( }  W' u
Jin K, Peel AL, Mao XO et al. Increased hippocampal neurogenesis in Alzheimer¡¯s disease. Proc Natl Acad Sci U S A 2004;101:343¨C347.: N! ?7 T0 \8 _8 O2 K! O: e+ W- t/ i

Curtis MA, Penney EB, Pearson AG et al. Increased cell proliferation and neurogenesis in the adult human Huntington¡¯s disease brain. Proc Natl Acad Sci U S A 2003;100:9023¨C9027.
5 h% ?! }4 f2 j# r% `& C" V* Z
Tattersfield AS, Croon RJ, Liu YW et al. Neurogenesis in the striatum of the quinolinic acid lesion model of Huntington¡¯s disease. Neuroscience 2004;127:319¨C332.# e2 N2 m* ~* t- w

Rice AC, Khaldi A, Harvey HB et al. Proliferation and neuronal differentiation of mitotically active cells following traumatic brain injury. Exp Neurol 2003;183:406¨C417.
( t. |/ h- d& a+ \
Jin K, Sun Y, Xie L et al. Directed migration of neuronal precursors into the ischemic cerebral cortex and striatum. Mol Cell Neurosci 2003;24: 171¨C189.& f4 v: y, ~6 f! ?1 L6 `( w

Yagita Y, Kitagawa K, Ohtsuki T et al. Neurogenesis by progenitor cells in the ischemic adult rat hippocampus. Stroke 2001;32:1890¨C1896.9 k! O8 u6 G9 y/ s" r8 u

Schwartz PH, Bryant PJ, Fuja TJ et al. Isolation and characterization of neural progenitor cells from post-mortem human cortex. J Neurosci Res 2003;74:838¨C851.

Yaworsky PJ, Kappen C. Heterogeneity of neural progenitor cells revealed by enhancers in the nestin gene. Dev Biol 1999;205:309¨C321.$ J: j  n+ o- P6 |: n# p2 a: }
% B) m7 W: |' ~1 m' y) j6 U
Takahashi M, Arai Y, Kurosawa H et al. Ependymal cell reactions in spinal cord segments after compression injury in adult rat. J Neuropathol Exp Neurol 2003;62:185¨C194.6 j4 ^8 y! K  g7 ~

Englund U, Bjorklund A, Wictorin K. Migration patterns and phenotypic differentiation of long-term expanded human neural progenitor cells after transplantation into the adult rat brain. Brain Res Dev Brain Res 2002; 134:123¨C141.

Mitsuhashi T, Aoki Y, Eksioglu YZ et al. Overexpression of p27Kip1 lengthens the G1 phase in a mouse model that targets inducible gene expression to central nervous system progenitor cells. Proc Natl Acad Sci U S A 2001;98:6435¨C6440." b; g% g0 D$ _9 p# }! v9 V" a

Aoki Y, Huang Z, Thomas SS et al. Increased susceptibility to ischemia-induced brain damage in transgenic mice overexpressing a dominant negative form of SHP2. FASEB J 2000;14:1965¨C1973.

Farooque M. Spinal cord compression injury in the mouse: Presentation of a model including assessment of motor dysfunction. Acta Neuropathol (Berl) 2000;100:13¨C22.( E0 X8 O4 _+ }5 z. f

Xu W, Chi L, Xu R et al. Increased production of reactive oxygen species contributes to motor neuron death in a compression mouse model of spinal cord injury. Spinal Cord 2005;43:204¨C213.

Maslov AY, Barone TA, Plunkett RJ et al. Neural stem cell detection, characterization, and age-related changes in the subventricular zone of mice. J Neurosci 2004;24:1726¨C1733.

Lie DC, Dziewczapolski G, Willhoite AR et al. The adult substantia nigra contains progenitor cells with neurogenic potential. J Neurosci 2002;22:6639¨C6649.
0 [. K5 q! \& S+ O2 f5 A  r  Y, M
Emsley JG, Mitchell BD, Kempermann G et al. Adult neurogenesis and repair of the adult CNS with neural progenitors, precursors, and stem cells. Prog Neurobiol 2005;75:321¨C341. Review.

Romanko MJ, Rola R, Fike JR et al. Roles of the mammalian subventricular zone in cell replacement after brain injury. Prog Neurobiol 2004;74:77¨C99.
" I' I. h9 @% `3 l4 n1 D: ^
Anthony TE, Klein C, Fishell G et al. Radial glia serve as neuronal progenitors in all regions of the central nervous system. Neuron 2004; 41:881¨C890.( B5 a% v* s& O" Z5 R+ r

Merkle FT, Tramontin AD, Garcia-Verdugo JM et al. Radial glia give rise to adult neural stem cells in the subventricular zone. Proc Natl Acad Sci U S A 2004;101:17528¨C17532.
' ~( k# ^7 J- ~7 a
Hasegawa K, Chang YW, Li H et al. Embryonic radial glia bridge spinal cord lesions and promote functional recovery following spinal cord injury. Exp Neurol 2005;193:394¨C410.

收藏0 分享0 顶0 踩0