双后肢大鼠增龄制备颈椎间盘退变动物模型

目的通过截除幼年大鼠双前肢建立颈椎间盘退变的动物模型。方法健康4周龄雄性SD大鼠76只，随机分为两组，手术组40只，对照组36只。手术组动物麻醉后于双上肢根部截除肢体，分别于术后3、6、9、12个月随机分为4组，每组10只处死大鼠后摄颈椎正侧位X线片，并切取椎体标本制备C2-C3至T2～T3的中欠状面组织学切片，分别进行HE、番红O染色行椎间盘组织学观察。对照组动物分别于实验开始后4、8、12、16个月分为4组进行与实验组相同的处理。结果截除双前肢后，双后肢大鼠全部存活，实验组大鼠术后9、12个月均出现颈椎间盘退变的X线征象，光镜检查证实其椎间盘均发生了严重的退变，脊索性髓核完全为纤维软骨性髓核取代，软骨终板缺损或消失，基质中胶原纤维排列紊乱，椎间盘突出并骨化。而正常大鼠的椎间盘仅发生轻度退变。结论本造模方法不损伤动物靶器官正常的解剖结构，成功率高、重复性好，符合人类颈椎间盘退变规律。     

成骨蛋白-1对髓核抽吸术后兔腰椎间盘组织病理变化的影响

目的:观察成骨蛋白-1(osteogenic protein-1,OP-1)对髓核抽吸术后兔椎间盘组织病理变化的影响.方法:32只日本大耳白兔,用21号针头行L1/2、L3/4椎间盘后外侧穿刺,抽吸出部分髓核组织,L3/4用微量注射器注射OP-1 25μl作为实验椎间盘(OP-1组),L1/2注射25μl生理盐水作为对照椎间盘(Saline组),L2/3作为正常对照椎间盘(正常组),术后2周、4周、8周、12周分别随机处死8只兔,每只取L1/2、L2/3和L3/4椎间盘,切片,行Masson染色,观察椎间盘组织病理学变化情况.结果:正常对照组椎间盘髓核组织胶原稀疏、排列有序,细胞可呈岛状分布,纤维环胶原纤维排列整齐,无扭曲及无分层现象,术后2周、4周、8周、12周椎间盘组织病理变化不明显.Saline组椎间盘术后2周时髓核部分缺失,胶原排列紊乱,出现大量分布不均匀的无定型颗粒;术后4周髓核组织裂隙形成,出现较多的类软骨细胞,胶原纤维扭曲严重;术后8周髓核组织广泛裂隙,胶原排列极其紊乱,出现介于类软骨细胞及纤维细胞之间的细胞,较明显的分层裂隙,胶原纤维极度扭曲,部分断裂;术后12周凝胶状髓核组织呈现明显纤维化,髓核内出现较多纤维样细胞,类软骨细胞数量明显减少,纤维环出现巨大分层裂隙,伴有部分纤维环断裂.OP-1组椎间盘术后2周髓核胶原排列尚有序,髓核细胞仍较多,纤维环形态接近正常;术后4周髓核组织轻微裂隙,胶原排列紊乱,髓核细胞减少,出现类软骨细胞,内层纤维环胶原纤维轻度扭曲;术后8周髓核组织较多裂隙,胶原扭曲,类软骨细胞增多,内层纤维环胶原纤维明显扭曲,排列紊乱;术后12周时类软骨细胞仍较多,出现少量介于类软骨细胞与纤维细胞之间的细胞,全层纤维环胶原纤维扭曲,排列紊乱,但外层纤维环仍完整,纤维环无巨大裂隙出现.结论;OP-1能延缓后外侧纤维环穿刺髓核抽吸术后兔腰椎间盘髓核细胞及纤维环的退变.     

椎间失稳诱发椎间盘退变的病理学观察

[目的]探讨新西兰大白兔腰椎关节突关节破坏能否诱发椎间盘退变的组织学改变。[方法]30只新西兰大白兔,体重2.25~2.95kg,雄性。随机分为骨性手术组和软组织手术组。软组织手术组仅骨膜下剥离L3~7的椎旁肌肉;骨性手术组完整切除L4、L5双侧下关节突、L5棘突,保留L5、L6上关节突。骨性手术组L4、5、L5、6椎间盘为实验组椎间盘,上下相邻的L3、4、L6、7为自身对照组椎间盘。软组织手术组L4、5、L5、6椎间盘为实验对照组椎间盘。术后1、2、4、及8个月行光学显微镜、电子显微镜检查。[结果]正常新西兰大白兔椎间盘由纤维环、髓核组成,纤维环胶原纤维排列规则,软骨样细胞镶嵌其中。髓核组织由大量细胞外基质和散在的细胞组成。随着术后时间延长,实验组椎间盘纤维环胶原纤维排列紊乱,细胞数进行性减少。术后4个月,实验组椎间盘开始出现大量退变细胞,表现为外形不规则,细胞膜破裂,线粒体肿胀,细胞核位于周边,核浓缩,核膜皱缩,异染色质较正常增加,核仁消失。术后8周实验组椎间盘开始出现大量死亡细胞,表现为溶酶体明显增多,细胞核扭曲,粗面内质网扩张,线粒体空泡化,死亡细胞外周的“巢”增厚呈多层排列,致密颗粒增多。[结论]L4、5、L5、6关节突关节破坏导致椎间失稳,椎间失稳后可以诱发出椎间盘退变的组织学改变。     

大鼠正常与退变性髓核突出导致神经根性疼痛的对比研究

目的探讨正常与退变髓核突出对大鼠疼痛阈值以及背根神经节中TNF-α表达的影响,研究椎间盘退变与神经根性疼痛之间的关系。方法72只大鼠随机分为4组:正常对照组(n=18)、假手术组(n=19)、正常髓核(N-NP)组(n=16)和退变髓核(P-NP)组(n=19)。对P-NP组大鼠利用尾椎椎间盘纤维环穿刺的方法建立椎间盘退变模型。分别取出N-NP组和P-NP组大鼠自体的正常髓核与退变髓核组织,置于手术显露后的腰5左侧神经根处,建立髓核突出致神经根性疼痛动物模型。采用行为学测试的方法分别观察各组大鼠术前1天,术后1、4、7、10、14、21天机械刺激阈值与热刺激阈值的变化;采用免疫组化方法分别检测术后第4、14天各组大鼠背根神经节中TNF-α的表达。结果行尾椎间盘纤维环穿刺后2周,组织学与MRI检查均证实椎间盘组织发生明显退变。对照组和假手术组动物未出现明显的痛觉过敏现象,N-NP组和P-NP组大鼠机械性刺激阈值均显著下降,该痛觉过敏现象持续至术后2周消失;与正常髓核组织相比,退变髓核所致机械性刺激阈值下降程度更为严重。各实验组均未发生热刺激阈值的规律性变化。术后第4、14天对照组和假手术组背根神经节中未见TNF-α明显表达,而正常及退变髓核组TNF-α表达量均显著升高。结论大鼠尾椎纤维环穿刺是建立大鼠椎间盘退变模型的一种有效方法。与正常髓核组织相比,发生退变的髓核组织可导致神经根性疼痛的加重,提示椎间盘退变过程中释放的炎症因子在疼痛的发生机制中可能起到了重要作用。     

去卵巢致肾虚的腰椎间盘退变模型的实验研究

目的:观察去前肢卵巢对大鼠腰椎间盘和椎体骨密度的影响,建立大鼠肾虚型腰椎间盘退变模型,探讨椎间盘退变的内在机制、椎间盘退变和骨质疏松之间的关系。方法:选择1月龄雌性SD大鼠30只,随机分为正常对照组、腰椎间盘退变组、肾虚型腰椎间盘退变组(复合模型组),每组10只。腰椎间盘退变组大鼠去除双前肢,肾虚型腰椎间盘退变组大鼠在去除双前肢3个月后,再去除双卵巢。8个月后,通过Micro-CT扫描观察椎体骨密度,藏红O-快绿染色法观测椎间盘组织形态学改变,免疫组织化学法观察Ⅱ、Ⅹ胶原在椎间盘中的蛋白表达,实时荧光定量聚合酶链式反应(real-time polymerase chain reaction,RT-PCR)法检测细胞外基质相关基因的表达,以评价去除双前肢和双卵巢对椎间盘退变和椎体骨密度的影响。结果:Micro-CT扫描发现,肾虚型腰椎间盘退变组动物椎体骨质疏松明显;藏红O-快绿染色法显示椎间隙变窄,肾虚型腰椎间盘退变组椎间盘组织退变明显,软骨板发育不全;免疫组织化学染色显示肾虚型腰椎间盘退变组相对于正常对照组,椎间盘内Ⅹ型胶原表达增加,Ⅱ型胶原表达降低;RT-PCR分析发现,腰椎间盘退变组和肾虚型腰椎间盘退变组Ⅱ型胶原(typeⅡcollagen,Col2a1)基因的表达较正常对照组低,3组比较差异有统计学意义(P=0.000,P=0.000﹚;腰椎间盘退变组和肾虚型腰椎间盘退变组聚集蛋白聚糖(aggrecan-1,Agc1)基因的表达较正常对照组低,差异有统计学意义(P=0.000,P=0.000﹚;腰椎间盘退变组和肾虚型腰椎间盘退变组Ⅹ型胶原(type X collagen,Col10al)基因的表达较正常对照组高,差异无统计学意义;肾虚型腰椎间盘退变组基质金属蛋白酶-13(matrix metalloproteinase 13,MMP-13)基因的表达较正常对照组和腰椎间盘退变组高,3组比较差异有统计学意义(P=0.000,P=0.000);腰椎间盘退变组和肾虚型腰椎间盘退变组聚集蛋白聚糖降解酶2(aggrecanase-2,ADAMTS-5)基因的表达较正常对照组高,差异有统计学意义(P=0.006,P=0.008)。结论:采用去双前肢和去卵巢的方式建立的大鼠腰椎间盘退变模型,出现了肾虚"骨象"———骨质疏松,并在组织形态学、分子细胞生物学等方面的表现与临床肾虚型腰椎间盘退变更加相似。     

"穿刺抽取髓核"诱导腰椎间盘退变的时间相关性评估

目的对穿刺纤维环抽取髓核诱导的腰椎间盘退变模型，进行时间相关的放射学和组织学评估，明确椎间盘退变程度的时间相关性。方法1岁山羊12只，以粗针穿刺纤维环抽取髓核（L1，2-15，6）建立腰椎间盘退变模型。术后第2、4、8、16周分别行放射学观察、髓核蛋白多糖（GAG）定量、组织学及微观结构评估。结果影像学示术后16周椎间隙高度显著降低（P〈0．01），但各椎间盘间差异无统计学意义（P〉0．05）。GAG定量示所有节段髓核内GAG含量随时间持续下降（P〈0．01），但与椎间盘序列间无相关性。大体标本及组织学观察显示，椎间盘退变组织学表现与抽取髓核后时间显著相关：术后2周组织学未见明显异常；4周始出现退变表现；16周时髓核已近完全纤维化。电镜观察示术后2—16周，髓核细胞从基本正常至大量凋亡，髓核基质逐渐纤维化。结论针刺抽取髓核法是较理想的腰椎间盘退变模型诱导方法。本研究观察16周，椎间盘退变未见缓解及自行修复，诱发的退变严重度与术后时间因素显著相关，而与椎间盘节段序列间无相关性。该模型在术后2周尚未出现明显组织学改变，或许是进行干预的良好时机。     

颈椎间盘纤维环及髓核的超微结构观察

目的：探讨在颈椎间盘纤维环及髓核退变中组织形态的变化。方法：对正常人、单纯颈椎间盘突出症、脊髓型颈椎病三组椎间盘纤维环及髓核进行电镜观察。结果：三组椎间盘胶原纤维无明显变化,单纯颈椎间盘突出症与脊髓型颈椎病人的退变椎间盘细胞较正常人有明显变化,表现为严重退变或细胞坏死。结论：单纯颈椎间盘突出症患者椎间盘以退变细胞为主,为退变早期阶段功能代偿期,脊髓型颈椎病椎间盘以坏死细胞为主,为退变晚期阶段,为不可逆期;颈腰椎间盘退变的组织形态学不完全相同。     

微创针刺旋切制备兔椎间盘退变模型

目的探讨微创针刺旋切制备兔椎间盘退变(intervertebral disc degeneration,IDD)模型的可行性。方法取40只新西兰大白兔,雌雄不限,体质量(2.9±0.3)kg;随机分为对照组和实验组(n=20)。对照组不予处理;实验组采用18G穿刺针在C臂X线机引导下经皮侧后方穿刺进入L4、5、L5、6椎间盘内,旋切髓核组织以促进椎间盘的退变。术后4、8、12、16周行大体观察、MRI观察并根据Pfirrmann分级法评价椎间盘退变情况,然后处死动物取材行Masson染色和番红O染色观察。结果实验组髓核组织颜色较对照组暗,弹性降低。对照组MRI T2加权像椎间盘信号强度早期未见明显改变,后期略减弱;实验组椎间盘信号强度随时间延长呈减弱趋势。根据Pfirrmann分级法评价椎间盘退变程度,两组随时间延长椎间盘退变程度均逐渐加重(P0.05);两组间比较除术后4周差异无统计学意义(P0.05)外,其余术后各时间点实验组椎间盘退变程度较对照组严重(P0.05)。Masson染色示随时间延长,对照组纤维环出现排列不规整,但结构仍完整;实验组纤维环排列紊乱,甚至出现断裂现象。番红O染色示对照组髓核细胞未见明显减少,实验组髓核细胞明显减少。结论微创针刺旋切法可成功制备兔IDD模型。     

腺相关病毒载体介导的TIMP1对人退变腰椎间盘髓核细胞蛋白多糖的影响

目的:探讨腺相关病毒(Adeno-associated virus;AAV)载体介导的基质金属蛋白酶组织抑制剂1(tissue inhibitor of metalloproteinases 1;TIMP1)对人退变腰椎间盘髓核细胞的生物学效应.方法:单层培养并鉴定人退变腰椎间盘髓核细胞.采用绿色荧光蛋白标记的腺相关病毒(rAAV2-EGFP)检测其对髓核细胞的转染效率.应用构建的rAAV2-TIMP1转染髓核细胞;通过细胞形态学观察、35S标记氨基酸整合法检测rAAV2-TIMP1对人退变腰椎问盘髓核细胞基质合成的影响.在35S检测中;以未转染的退变髓核细胞做为正常对照组.结果:光镜下观察所培养的细胞类型以成纤维样细胞为主;Ⅱ型胶原免疫组化和番红O染色鉴定培养细胞为髓核细胞.AAV转染人退变腰椎间盘髓核细胞的转染效率为12%.35S标记整合法检测rAAV2-TIMP1转染组每分钟计数值为341.43±42.85;正常对照组为224.20±29.26;两组间比较差异有统计学意义(P＜0.05).结论:TIMP1能够促进退变椎间盘髓核细胞蛋白多糖的合成.     

单侧坐骨神经干髓核移植对大鼠双足痛阈的影响及其可能机制的探讨

目的观测髓核组织对单侧坐骨神经干的损伤作用,探讨这种损伤作用与大鼠双足痛阈之间的关系。方法24只雄性SD大鼠(体重260~280g)随机分为四组:、假手术组、脂肪组、肌肉组、髓核组,每组n=6。另外3只雄性SD大鼠用来提供异体脂肪、肌肉和髓核,移植到各组一侧坐骨神经干,用神经行为学的方法观测大鼠双足痛阈变化,并于术后第10d、20d取植入侧坐骨神经用病理切片组织化学染色方法光镜观察坐骨神经干组织学变化。结果术后3、5、7、10、15、20、25、30、35d对照组双后肢均未出现痛觉过敏,而髓核组双侧后肢均出现明显的痛觉过敏,并且以术后7~10d最明显;组织学光镜观察发现髓核组植入侧坐骨神经干出现水肿、大量淋巴细胞浸润,部分髓鞘呈空泡样变等损伤表现,术后10d表现明显。结论髓核组织对坐骨神经干有炎性损伤作用,此损伤作用与痛觉过敏可能存在联系。     

Nucleus pulposus allograft retards intervertebral disc degeneration

Autogenous implantation of nucleus pulposus or nucleus pulposus cells that were activated by coculture retards intervertebral disc degeneration, but harvesting such grafts causes disc degeneration at the donor site. This study examined whether nucleus pulposus allografts similarly retard disc degeneration and whether such allografting induces immunologic rejection. Japanese White rabbits served as donors and recipients for allografts. Lumbar disc degeneration was induced by aspirating the nucleus pulposus. Two weeks later, intact nucleus pulposus or nucleus pulposus cells were injected and compared with a sham procedure and normal control. The recipients' discs were examined histologically and immunologically at intervals for 16 weeks. Discs receiving an intact nucleus pulposus showed the least degeneration, followed by discs receiving nucleus pulposus cells, both of which were better than no treatment. These findings correlated directly with the intensity of immunochemical staining for Type II collagen. Allogeneic grafts did not induce any appreciable host-versus-graft response. Injection of nucleus pulposus and nucleus pulposus cells retards intervertebral disc degeneration. However, injection of intact nucleus pulposus is more effective than injection of nucleus pulposus cells alone. The intercellular matrix plays an important, but poorly understood, role in preserving intervertebral discs.     

椎体终板损伤对兔椎问盘髓核Ⅰ、Ⅱ型胶原的影响

目的 观察椎体终板损伤对兔椎间盘髓核Ⅰ、Ⅱ型胶原的影响并探讨其机制.方法 4个月龄清洁级日本大白兔12只,完整取出40个包含终板的完整椎间盘(L2-L5),随机分为实验组和对照组,每组20个.实验组参考Daniel Haschtmann的方法建立终板损伤模型.椎间盘整体培养2周后,免疫组织化学方法观察椎间盘髓核中Ⅰ、Ⅱ型胶原的表达情况,并用HMIAS-2000图像分析系统进行半定量分析.结果 免疫组织化学染色显示:实验组椎间盘髓核Ⅰ型胶原的表达比对照组高;而Ⅱ型胶原的表达则比对照组低,差异均有统计学意义(P<0.05).结论 外伤致椎体终板损伤后会导致椎间盘髓核Ⅰ、Ⅱ型胶原的变化,继而加速椎间盘退行性变.     

两种骨水泥渗漏对椎间盘影响的实验研究

目的 探讨椎体成形术时骨水泥渗漏是否会引起椎间盘退变，以及椎间盘退变程度与骨水泥类型是否相关。方法 选用8只成年家犬，以每只犬L2-3、L3-4、L4-5椎间盘为实验对象，随机分为对照组、聚甲基丙烯酸甲酯（polymethylmethacrylate，PMMA）与磷酸钙骨水泥（calcium phosphate cement，CPC）3组。对照组仅行椎间盘穿刺，不注入任何物质，PMMA组及CPC组均各向椎间盘注入0．1ml骨水泥。术前及术后24周摄正、侧位X线片，计算椎间盘高度指数百分数（disc height index percentage，DHIP）。术后24周行MR检查，计算MRI指数。组织学检查参照Masuda标准对椎间盘退变程度评分并分析。结果 术后24周X线片显示对照组椎间隙无狭窄，病理学检查未见椎间盘退变。PMMA、CPC组椎间盘MRI显示：椎间隙有狭窄，R加权像髓核信号不同程度降低且不均一，其相对高信号区面积减小，髓核形态不规则，纤维环与髓核界限不清。组织学检查显示髓核细胞数量不同程度减少，空泡变小。髓核的细胞外基质不同程度压缩，纤维环断裂或扭转。3组DHIP、MRI指数、组织学评分的差异均有统计学意义（P〈0.01）。结论 PMMA、CPC注入椎间盘会导致椎间盘退变，PMMA所致椎间盘退变较CPC更为严重.     

A study of the effects of bipedism and upright posture on the lumbosacral spine and paravertebral muscles of the Wistar rat

Twenty-one bipedal rats were prepared by forelimb amputation and reared with 19 control rats. All of the bipedal rats became proficient upright walkers. There was significant anterior wedging of the lower lumbar vertebral bodies in all of the bipedal rats and four had radiographic evidence of degenerative disc disease. Five bipedal rats developed lumbosacral disc herniations, and the lumbar neural canal was significantly smaller in the bipedal population. There was no difference in radionuclide uptake between the two groups. Histochemical analysis of the psoas and multifidus muscles showed a significant shift from type I to type II fibers in the psoas and from type II to type I fibers in the multifidus in the bipedal population. These results indicate that upright posture places considerable stress on the lumbosacral spine and paravertebral muscles of the rat.     

Collagens in the injured porcine intervertebral disc

Spinal pain often is thought to be due to degeneration and mechanical failure of the intervertebral disc. Since the mechanical strength of the tissue depends on collagen fibers, the present study was designed to investigate the reactions in collagen metabolism after an experimentally induced disc injury. Five domestic pigs underwent an incision in the anterior part of the annulus fibrosus of disc L4-L5 through a retroperitoneal approach. The animals were killed 3 months postoperatively, and the injured discs and intact discs (controls) from different animals were removed for chemical analysis. Slices were cut from seven different parts across the disc. The concentration of total collagen (hydroxyproline [Hyp]), the activities of the two key enzymes in collagen biosynthesis (prolyl 4-hydroxylase [PH] and galactosylhydroxylysyl glucosyltransferase [GGT]), and the concentration of mature collagen crosslinks (hydroxypyridinium [HP]) were determined. In all experimental discs, the morphology had changed considerably: the nucleus pulposus was small, fibrous, and yellowish. The annular lamellar structure was partially destroyed and had been replaced by granulation tissue in the region of the injury. Large osteophytes had formed at the ventral edges of the vertebral bodies. In the nucleus pulposus, the Hyp concentration and the activities of PH and GGT were significantly increased, whereas the water content had decreased. The concentration of HP crosslinks was decreased in the anterior annulus fibrosus.     

Changes in the nucleus pulposus of the intervertebral disc in bipedal mice. A light and electron microscopic study

Bipedal mice were produced by clipping the forelimbs and tails of mice within one week of birth. Using light and electron microscopy, the nucleus pulposus of the lumbar intervertebral disc in the bipedal mice was compared with that in normal mice at three, six, and 12 months of age. In normal neonatal mice, the nucleus pulposus is composed of densely packed notochordal cells, which undergo degenerative changes and decrease in number with age. In the bipedal mice, degenerative changes in the nucleus pulposus were accelerated, and herniation of the nucleus pulposus occurred frequently. At the same time, active chondrocytes associated with cartilage matrix appeared in the nucleus pulposus. This sequence of morphologic changes in the nucleus pulposus of the bipedal mice resembles the age-related changes that occur in the nucleus pulposus of the human intervertebral disc. These morphologic changes can be accelerated by creating abnormal mechanical stress. Chondrocytes in the nucleus pulposus may develop from surrounding cartilaginous tissue--cartilage plates and annulus fibrosus.     

果胶/聚乙烯醇复合水凝胶人工腰椎髓核置换的实验研究

目的 评价果胶/聚乙烯醇复合(CoPP)水凝胶人工髓核置换延缓腰椎间盘退变的效果.方法 以36只成年新西兰大白兔,建立腰椎髓核置换的动物模型,显露L3～4和L4～5两个椎间盘.L4～5椎间盘用16号针头穿刺后将聚乙烯醇(PVA)或CoPP水凝胶试件植入其内,L3～4椎间盘行假手术处理或只用针头穿刺而不植入试件.由此,全部实验椎间盘分成假手术组、穿刺组、PVA组和CoPP组.于术前、术后1、3、6个月摄腰椎侧位X线片,测量椎间盘高度指数百分比,并对手术节段椎间盘进行组织学评估.结果 实验动物均存活,无伤口感染或手术并发症发生,无PVA、CoPP假体试件突出或明显移位.PVA组和CoPP组椎间盘高度丢失明显小于穿刺组(P<0.01),与假手术组相比差异无统计学意义(P>0.05).PVA、CoPP两组在术后6个月内椎间盘退变的程度无明显差异,但随着术后观察时间的延长,两者治疗效果的差别逐渐增大,PVA组椎间盘退变明显,CoPP组退变相对缓慢.结论 CoPP水凝胶人工髓核置换术可保留椎问盘高度和填充髓核空间,延缓纤维环的退变,具有潜在的临床应用价值.     

Comparison of neuropathic pain induced by the application of normal and mechanically compressed nucleus pulposus to lumbar nerve roots in the rat.

We studied whether applying nucleus pulposus tissue, obtained from tail intervertebral discs that had been subjected to chronic mechanical compression, to the lumbar nerve roots produces hyperalgesia, which is thought to be a pain-related behavior in the rat. An Ilizarov-type apparatus was used for immobilization and chronically applied compression of the rat tail for eight weeks. Three weeks after application of extracted nucleus pulposus tissue on the lumbar nerve roots, motor function, sensitivity to noxious mechanical stimuli was measured. Eight weeks after application of the apparatus, the instrumented vertebrae were resected and sections were stained with hematoxylin and eosin to evaluate degeneration of the intervertebral disc. Mechanical hyperalgesia observed in rats treated with the compressed nucleus pulposus tissue was greater and of longer duration than in the rats treated with normal and non-compressed discs. The nucleus pulposus in the instrumented vertebrae showed some histological degeneration. In conclusion, chronic mechanical compression of nucleus pulposus, which resulted in degeneration to some extent, enhanced mechanical hyperalgesia, which was induced by application of nucleus pulposus on the nerve root in the rat. Degenerative intervertebral discs might induce more significant pain than normal intervertebral discs.     

Olfactory stem cells can be induced to express chondrogenic phenotype in a rat intervertebral disc injury model

BackgroundIn humans, lower back pain is one of the most common causes of morbidity. Many studies implicate degeneration of intervertebral discs as the cause. In the normal intervertebral disc, the nucleus pulposus exerts a hydrostatic pressure against the constraining annulus fibrosus, which allows the disc to maintain flexibility between adjacent vertebrae, while absorbing necessary compressive forces. The nucleus pulposus performs this role because of its hydrophilic gel-like structure. The extracellular matrix of the nucleus pulposus is up to 80% hydrated, as a result of large amounts of the aggregating proteoglycan, chondroitin sulfate proteoglycan (CSPG). This proteoglycan is enmeshed in a randomly orientated network of fine collagen Type II (CT2) fibers.Study design and purposeA useful adult tissue-derived stem cell is that from the olfactory mucosa, the organ of smell. These cells, accessible in humans from nasal biopsies, are multipotent and are able to make many cell types from all germ layers. They are easily grown in vitro and can be expanded to large numbers and stored frozen. These qualities indicate the potential for autologous transplantation for disc repair. In this article, using a rat model, we explore the hypothesis that olfactory stem cells can differentiate into a nucleus pulposus chondrocyte phenotype in vitro, as well as in vivo after transplantation into the injured intervertebral disc.Patient sampleFemale rats (14 weeks) were anesthetized with xylazine/ketamine. The abdominal wall was shaved and injected with local anesthetic (lidocaine) before incision. The ventral part of the lumbar spine, including two intervertebral discs, was exposed. Disc degeneration was then induced in the two exposed discs by needle aspiration of the nucleus pulposus. The prominent spina iliaca posterior superior was used as an anatomical landmark for identification of the first disc. Two weeks later, one injured intervertebral disc was exposed in a second, similar, surgery and 20,000 olfactory neurosphere-derived cells were transplanted with a 25-G needle.Outcome measuresIn vitro induction of nucleus pulposus chondrocyte phenotype is measured by the percentage of cells expressing CT2 and CSPG. In vivo, a successful outcome is evidence of engraftment of donor-derived cells and their expression of CT2 and CSPG.MethodsIn this article, we tested two hypotheses: the first that progenitor cells within olfactory neurospheres could be induced to express markers distinctive of the nucleus pulposus when placed in vitro in a coculture experiment. The second hypothesis tested the same induction in genetically labeled transplanted cells within damaged vertebral discs in vivo. The two markers measured are those held by current literature to engender the necessary cushioning characteristics of nucleus pulposus, CT2 and CSPG.ResultsOur experiments demonstrated virtually 100% induction of these two markers in vitro. Also, this induction was achieved in donor-derived cells after delivery to the nucleus pulposus region of animals whose discs had previously been lesioned 2 weeks before transplant.ConclusionsThese results provide a rationale for moving toward more extensive larger animal studies for assessment of regeneration before human trials where relief of symptoms can be more easily assessed.     

Reinsertion of stimulated nucleus pulposus cells retards intervertebral disc degeneration: an in vitro and in vivo experimental study.

Reinsertion of autogenous nucleus pulposus, an innovative method to delay further disc degeneration, has been proved with an experimental animal model. This study examined whether coculture of nucleus pulposus cells with annulus fibrosus cells (a) activates annulus fibrosus cells and (b) retards disc degeneration when reinserted into the disc in a rabbit model of disc degeneration. Coculture of the two cell types stimulated proliferation of each, as indicated by increased DNA synthesis measured by increases in DNA polymerase alpha expression and uptake of 5-bromo-2'deoxy-uridine assessed by an enzyme-linked immunosorbent assay. In a model of disc degeneration in rabbits, reinsertion of activated nucleus pulposus cells delayed the formation of clusters of chondrocyte-like cells, the destruction of disc architecture, and the elaboration of type-II collagen as measured immunohistochemically compared with no treatment. The direct reinsertion of activated nucleus pulposus cells into the disc offers a promising line of investigation for delaying intervertebral disc degeneration, although these results obtained with notochordal cells may not necessarily apply when mature central nucleus pulposus cells are used.