骨骺干细胞相关研究进展

骨骺干细胞是近年来发现的保持有干细胞特性并能定向分化的成体干细胞之一,它的分离纯化使得尚未找到十分理想的种子细胞的关节软骨损伤组织工程修复研究看到了希望.研究发现PTHrP、Ihh和Notch等信号转导系统在调节骨骺干细胞分化和软骨内成骨中起着重要作用.软骨发育不良、原发性滑膜软骨瘤等多种软骨发育障碍性疾病与骨骺干细胞的特征性标记物成纤维细胞生长因子受体-3的基因突变有关.骨骺干细胞在修复软骨与骨缺损方面的研究已取得可喜进展,在未来临床研究中将有广泛的应用价值.     

甲状旁腺激素和甲状旁腺激素相关蛋白在正常及骨性关节炎软骨中作用机制的研究进展

目的综述在正常和骨性关节炎(osteoarthritis,OA)的关节软骨及软骨下骨中,甲状旁腺激素(parathyroid hormone,PTH)和甲状旁腺激素相关蛋白(parathyroid hormone-related protein,PTHrP)的作用机制研究进展。方法广泛查阅近年来有关PTH和PTHrP对正常和OA关节软骨作用机制的文献,并进行总结与分析。结果 PTH和PTHrP可抑制OA软骨细胞的肥大分化及凋亡,促进其增殖,从而对OA软骨细胞起到保护作用;OA软骨下骨成骨细胞对PTH的反应下降。结论 PTH、PTHrP可能通过多种信号通路参与软骨降解和软骨下骨重塑,并对OA进展起到延缓和保护作用。     

软骨生长板基因调控机制的研究进展

脊椎动物骨骼的形态与大小因功能各异而相差悬殊,但多数骨骼却是以相同的生长方式-软骨内成骨-长成的.位于骨骺与骨干交界处的软骨生长板(growth plate)-即骺板(epiphyseal plate)-不断增生、增厚,间质发生钙化,软骨细胞凋亡,继而新骨沉积,形成骨干的纵向生长.在幼年时期,软骨的增生、退化与新骨生成的速率保持平衡,从而保证了在骨干长度增加的同时,生长板能够保持一定的厚度.当软骨生长板发育到成熟阶段,软骨增殖与成骨活性中止,生长板完全被骨化,骨的纵向生长也随之停止.因此,软骨生长板调节控制骨的纵向生长速度与骨的最终长度.骨的生长与分化受局部因素(如骨形态发生蛋白、成纤维细胞生长因子、胰岛素样生长因子等)与全身因素(如生长激素、性激素、甲状腺素等)的调控.本文就近年来局部因素对软骨生长板基因调控机制的研究进展进行综述.     

生物力学因素对椎体生长板的影响和临床意义

终板是脊椎的重要组成部分，在生长期，又被称为椎体生长板，在青春发育期前发挥着与长骨骨骺相同的作用，是脊柱纵向生长的最重要结构。它以软骨内成骨的方式使脊柱纵向生长，但是其软骨细胞的排列并不具备长骨骨骺的典型分层结构。生物力学因素在椎体的生长发育过程中起重要作用，尤其是张应力和压应力的互相结合，影响椎体生长板的生长，进而引起椎体畸变。此方面研究对临床工作具有指导意义，现将生物力学因素对椎体生长板的影响作一综述。     

软骨内成骨的调控

骨骼的纵向生长不仅需要激素的调节，同时也需要旁分泌的局部调节因子的调节，因而调节因子可分为系统性调节因子和局部调节因子。系统性调节因子包括生长激素、甲状腺素、雌激素、雄激素、维生素D3、视黄酸及皮质激素等。局部调节因子包括骨形态发生蛋白（BMPs）、成纤维细胞生长因子（FGFs）、Ihh／甲状旁腺素相关肽（PTHrP）及类视黄醇等，它们与核内转录因子相互作用，调节与控制软骨内成骨的进程。现对近年来软骨内成骨的主要调节因子研究综述如下。     

Indian Hedgehog信号通路在软骨细胞成熟及转分化过程中的调控作用

目的 探究Indian Hedgehog（IHH）信号通路对软骨内成骨过程中软骨细胞成熟以及转分化的影响。方法 取10日龄野生型小鼠的胫骨组织,采用原位杂交和免疫组织化学染色检测生长板区域IHH信号通路相关分子Ihh、Ptch1和Gli1的表达水平。构建肥大软骨细胞特异性Ihh基因敲除小鼠（Col10a1^Cre/+; Ihh^null/C）,并采用影像学检查和阿利新蓝染色评估该小鼠的骨骼发育状况。构建肥大软骨细胞IHH信号通路持续激活小鼠（Col10a1^Cre/+; R26Smo^M2/M2和 Col10a1^Cre/+; Ptch1^LacZ/C）,采用HE染色、原位杂交和TUNEL染色分别对受精15.5天胎鼠胫骨组织形态结构、Ihh（肥大软骨细胞分子标志物）和Col1a1（成骨细胞分子标志物）以及肥大软骨细胞凋亡水平进行检测;另外应用HE染色对10日龄小鼠的胫骨组织进行组织学分析。结果 肥大软骨细胞合成分泌IHH,但不表达Ptch1和Gli1。抑制肥大软骨细胞合成IHH蛋白会导致出生后小鼠出现侏儒症;X线检查结果显示小鼠出现严重的骨骼发育不良,包括胸廓狭小、球形头骨以及椎骨发育异常等表现。持续启动IHH信号通路时,胚胎早期软骨细胞成熟分化过程虽未见异常,但是出生后小鼠的骨小梁、骨内膜以及皮质骨等结构均出现一定的异常表现。结论 IHH信号通路虽然不参与肥大软骨细胞的终末分化过程,但在软骨细胞转分化的过程中起到了重要的调控作用。     

自噬在软骨内成骨中的调控作用研究进展

哺乳动物的骨发生有两种不同的形式,一种是膜内成骨,另一种是软骨内成骨,后者是骨骼形成的主要方式。软骨内成骨是由间充质细胞先分化为软骨,随着血管的产生,软骨逐渐被骨组织取代,此过程受到一系列激素及生长因子相互作用、相互调节的严密调控。骨骺生长板中的软骨细胞分裂、成熟、肥大是软骨内成骨的关键过程。自噬是一种广泛存在于细胞中的高度保守的细胞降解代谢途径,利用溶酶体降解胞内物质,重复利用大分子的过程。缺氧和营养缺乏的内环境能使自噬活性相关控制基因激活,大量吞噬溶酶体形成,提高自噬水平。生长板无血管的结构使得位于生长板中间的软骨细胞处于氧气和营养物质相对缺乏的内环境中,对氧气和营养物质较敏感,自噬活性改变,产生相应的调控作用。近年来,不仅自噬在癌症、衰老、中枢神经系统损伤等领域的研究取得了较大进展,学者们对自噬在软骨细胞中的作用及其机制给予广泛关注,发现自噬有利于软骨细胞的生存与细胞外基质的降解。本文主要从自噬调控软骨内成骨的作用及相关调控因子,对自噬在软骨内成骨中的调控进行相关综述,以期能对相关骨代谢性疾病的治疗提供新的思路。     

音猬因子信号通路与骨质疏松症关系的研究进展

骨发育的过程受到多种信号通路的调节,如Wnt、Notch、BMP、Hedgehog信号通路等。Hedgehog信号通路对骨形成的作用在过去的二十几年已经被证实。音猬因子(Ssonic hedgehog,Shh)在Hedgehog家族中表达最广泛,在该信号传导通路上对轴骨、四肢骨、颅面骨等骨骼的形成起着重要作用。骨质疏松症发病机制归根到底是成骨细胞的骨形成能力与破骨细胞的骨吸收之间的平衡被打破,并且成骨细胞的骨形成作用下降是其主要影响因素之一。本文主要从分子水平对Shh信号通路与影响骨质疏松症发生的几个主要因素进行综述,为Shh信号通路应用于骨质疏松的防治提供理论依据。     

兔髂骨生长板细胞的培养及体内成软骨作用的研究

目的 建立大量生产髂骨生长板软骨细胞的培养及保存方法，观察髂骨生长板细胞在裸鼠体内的成软骨作用，为生长板组织工程提供种子细胞。方法 取二周龄兔髂骨生长板软骨，经机械剪切和化学消化作用后，接种、培养及液氮保存，通过显微镜观察其生物学表现，并通过甲苯胺兰、碱性磷酸酶染色及Ⅱ型胶原染色对其生物学特性进行签定。将生长良好的第二代细胞注入裸鼠背部，于第四周取材，进行组织学观察。结果 细胞可在体外大量增殖并在六代内无明显反分化，但缺乏向肥大细胞进一步分化的能力。冷冻复苏细胞存活率为92％。注射的细胞悬液可在裸鼠体内形成软骨组织，并进一步向肥大细胞转化。结论 成功建立了髂骨生长板细胞的培养及冻存方法，证明髂骨生长板细胞可在体内进一步形成软骨组织并向肥大期细胞转化。     

生长板损伤修复的研究进展

生长板是软骨内成骨的发育中心,在形态和功能上可分为静息带、增殖带、前肥大带与肥大带。生长板损伤常导致儿童肢体长度差异和成角畸形等骨骼生长缺陷。目前的矫形手术损伤较大且效果有限,尚缺乏有效的生物疗法。动物模型的生长板损伤后修复的细胞与分子事件可分为4个阶段:炎症期、成纤维期、成骨期与重塑期。现有研究表明,参与上述过程调控的相关分子,如炎症细胞因子肿瘤坏死因子α、促有丝分裂的血小板衍生生长因子以及调节成骨的血管内皮生长因子、骨形态蛋白均参与生长板损伤修复的调节。对生长板损伤修复机制的探究可能为生物疗法的研发提供新的靶标。此外,软骨组织工程的发展,尤其是间充质细胞的应用也为生长板损伤修复提供潜在的干预措施。     

Transforming growth factor-β1 and fibroblast growth factors in rat growth plate

Chondrocytes in the growth plate progress in an orderly fashion from resting through proliferating to hypertrophic cells. In the region of hypertrophic chondrocytes, the cartilage is invaded by capillary loops and endochondral ossification is initiated. It is currently believed that growth factors may regulate the proliferation and maturation of chondrocytes and the synthesis of extracellular matrix in the growth plate. The ordered sequence of proliferation and differentiation observed in the growth plate provides a unique opportunity to study the role of acidic fibroblast growth factor, basic fibroblast growth factor, and transforming growth factor-β1 in the regulation of these processes. In this study, expression of the mRNA of these growth factors was examined using total RNA extracted from the physis and epiphysis of rat tibias. Transforming growth factor-β1 mRNA was detected by Northern hybridization. Expression of the genes encoding acidic and basic fibroblast growth factors was demonstrated by polymerase chain reaction amplification. In addition, using polyclonal antibodies against these growth factors, we localized them by immunohistochemical analysis. Strong intracellular staining with a predominantly nuclear pattern was observed in chondrocytes from the proliferating and upper hypertrophic zones. In contrast, chondrocytes in the resting zone stained only faintly for the presence of these growth factors. Some chondrocytes in the resting zone adjacent to the proliferating zone stained with these antibodies, and the antibodies also stained cells in the zone of Ranvier, which regulates latitudinal bone growth. Lastly, the location of transforming growth factor-β1 was examined further with use of a polyclonal antipeptide antibody specific for its extracellular epitope. Interestingly, extracellular staining for transforming growth factor-β1 was observed only around chondrocytes in the hypertrophic zone. These results suggest a role for these growth factors in the regulation of proliferation and maturation of chondrocytes and in endochondral ossification.     

Serum leptin values in relation to bone density and growth hormone-insulin like growth factors axis in healthy men

A novel action of leptin on bone formation has recently been described in animals. However, in humans, studies provide data, that, are less conclusive. So far, few studies investigated the leptin-bone density association in males. Moreover, it has been suggested that GH, IGF-1 and IGFBP-3 may be major players in the hormonal or paracrine pathways that regulate bone cell metabolism. Also, leptin has been shown to modulate the GH/IGF pathway. The aim of this study was to clarify further this issue by investigating (a) the influence of serum levels of leptin, GH, IGF-1 and IGFBP-3 on bone mass in various skeletal sites and, (b), the relationship between leptin and the GH/IGF axis. 363 healthy individuals were investigated. BMD and serum leptin, GH, IGF-1 and IGFBP-3 serum levels were assessed. Our results indicate that 11% of healthy males had bone density with T scores 相似文献   

胃癌哨兵淋巴结位置分布及其转移相关因素

目的　探讨胃癌哨兵淋巴结位置分布规律以及导致其转移的相关因素。方法　调查2 7例单个转移淋巴结、80例单组转移淋巴结的位置分布 ,比较单个转移淋巴结和 111例无转移淋巴结病人的临床病理参数。结果　 2 7个单个转移淋巴结中有 2 5个位于第 1站 ,跳跃转移 2个 ;2 1例胃下区、胃中区癌哨兵淋巴结中 16个在第 3、4组 ,6例胃上区癌哨兵淋巴结中 3个位于第 1组。pT3 期胃癌哨兵淋巴结转移的危险性高于pT1胃癌 ,比数比 (OR)为 4 92 6 (P <0 0 1) ,胃上区癌比胃下区癌哨兵淋巴结更易发生转移 (OR =4 381,P <0 0 5 ) ,早期胃癌哨兵淋巴结的转移危险性低于BorrmannⅠ型胃癌 (OR =0 0 82 ,P <0 0 5 )。结论　胃癌哨兵淋巴结多位于肿瘤附近 ,跳跃转移少见 ;肿瘤侵犯深度以及所在部位与哨兵淋巴结发生转移有关 ,利用胃癌哨兵淋巴结可以指导胃癌淋巴结切除范围的选择     

The growth hormone and insulin-like growth factor axis: its manipulation for the benefit of growth disorders in renal failure

Renal failure is associated with dramatic changes in the growth hormone/insulin-like growth factor (GH/IGF) axis. In children, this results in growth retardation, which is treated with injections of recombinant human GH (rhGH). Given the many recent advances in the knowledge of the components of the GH/IGF axis, it is timely to review the role of GH in renal failure and to discuss likely new treatments for growth failure. Renal failure is not a state of GH deficiency but a state of GH and IGF resistance, making other approaches to manipulating the GH axis more logical than treatment with rhGH alone. Although in children rhGH is safe, in critically ill adults it can be lethal. As the mechanisms of these lethal actions of rhGH are unknown, caution is advised when using rhGH outside approved indications. In renal failure, an optimal balance between safety and efficacy for growth may be achieved with the use of the combination of rhGH and rhIGF-I, as animal studies have shown synergistic growth responses. However, inhibition of the GH axis, with the use of GH antagonists, is likely to be tested clinically given the beneficial effects of GH antagonists on renal function in animal models of renal disease. Manipulating IGF-I by either administering rhIGF-1 or its binding proteins or increasing IGF-I bioavailability with the use of IGF displacers could prove to be a safer and more effective alternative to the use of rhGH in renal failure. In the future, both rhGH and rhIGF-1 likely will be included in growth-promoting hormone cocktails tailored to correct specific growth disorders.     

Reimplantation of growth plate chondrocytes into growth plate defects in sheep

Defects in growth plates due to trauma, infection, or genetic causes can result in bone formation across the defect, bridging the epiphysis and metaphysis, resulting in growth arrest and limb deformation. We have investigated the capacity of implanted chondrocyte cultures to prevent this process. Sheep growth plate chondrocytes were isolated, and after culture at high density produced easily manipulated cartilaginous discs. The tissue was implanted into growth plate defects produced in lambs and the response was assessed histologically. Following implantation, cultures continued to proliferate and maintain a cartilage-like matrix. After 8 to 12 weeks, hypertrophic maturation chondrocyte columnation, and associated endochondral calcification were observed. Culture implantation was always associated with local immune inflammatory reaction, which continued throughout the course of investigation. Cellular survival was variable and resulted in the presence of viable implants as well as residual cartilage matrix devoid of chondrocytes; however, implanted chondrocyte discs always prevented bone bridge formation. These findings encourage the expectation that cultured chondrocytes may provide a useful replacement for the inert interpositional materials currently used in the treatment of growth arrest. The potential of this technique for growth plate replacement, however, requires a more predictable rate of implant survival. The likely reasons for implant loss are discussed.     

Distrubance of growth hormone-insulin-like growth factor axis in uraemia

The growth hormone/insulin-like growth factor (IGF) axis is disturbed in uraemia. Elevated plasma growth hormone (GH) levels despite diminished growth suggest GH resistance, which may be due in part to a decreased expression of the growth hormone receptor at the cell membrane. The hepatic production of IGFs under the control of GH is impaired. Furthermore, there is an excess of IGF-binding protein over total IGF as a consequence of reduced renal clearance of low-molecular-weight subunits of the IGF-binding protein (IGF-BP). This results in an absolute (diminished production) and a relative (low bioavailability) deficiency of IGF. Recombinant human growth hormone (rhGH) in doses of 4 IU/m² per day is able to induce catch-up growth in children with preterminal and terminal renal failure. The growth stimulation of exogenous GH is attributed to its potency to increase the ratio of IGF-I to IGF-BP, followed by a normalization of IGF bioactivity. In renal transplanted children growth is not only disturbed by decreased renal function but also by steroid treatment. Corticosteroids, are responsible for catabolism, for suppression of pituitary GH secretion and for inhibition of local production of IGFs. Exogenous rhGH is able to counteract these growth-inhibiting effects. However, it remains to be seen whether long-term GH treatment definitely improves final adult height.