Characterization of Demineralized Bone Matrix-Induced Osteogenesis in Rat Calvarial Bone Defects: III. Gene and Protein Expression

Our previous studies of rat cranial defect repairs after the implantation of demineralized bone matrix (DBM) have demonstrated that healing occurs initially and principally by the direct induction and proliferation of osteoblasts derived principally from resident mesenchymal stem cells of the dura, and to a lesser extent by resident mesenchymal stem cells of the connective tissues beneath the skin flap. A small amount of cartilage is also synthesized after the direct process of ossification occurs. To further confirm the molecular phenotypes of the repair cells in rat cranial defects, the present study evaluated mRNA expression and synthesis of collagens I, II, and X and osteocalcin in the DBM-induced repair tissue by Northern blot analyses, autoradiography after in vivo ³H-proline labeling of collagen, and immunohistochemistry. The results demonstrated that osteocalcin mRNA appeared in small amounts by day 4 and continued to increase over the experimental period. Much lesser quantities of collagen types II and X mRNAs appeared by day 6 and day 8, respectively. Collagen type I mRNA was present at all times examined but its expression significantly increased by day 5. Autoradiographic and immunohistochemical studies showed that type II collagen was not detected whereas type I collagen was synthesized on days 3–5. The data provide definitive molecular evidence confirming that the initial and by far the major pathway of cranial defects repair induced by implantation of DBM is by the direct induction of resident mesenchymal stem cells to osteoblasts and the direct formation of bone, which is spatially and temporarily distinct from the later formation of cartilage. Received: 30 November 1999 / Accepted: 21 March 2000     

Mineralization and alkaline phosphatase activity in collagen lattices populated by human osteoblasts

Adult human osteoblastic cells were grown in a native type I collagen gel. Proliferation and viability analyses showed that cells rapidly stopped dividing and became blocked in the G0G1 phase (91% on day 13). Carboxyfluorescein diacetate cell staining and flow cytometry showed that osteoblasts were viable for the first 16 days and then viability decreased (58% viable cells on day 22). Osteoblasts were able to retract the matrix. Betaglycerophosphate (βGP) stimulated the deposition of mineral particles in the collagen network, and electron probe microanalysis showed that they were principally calcium and phosphorus, with a Ca/P ratio of about 1.7. Various times of βGP supply were tested. We compared 10 mM βGP added only once at day 0, or continuously from day 0, day 8, or day 21. Mineralization was observed in conditions where βGP was added at day 0. Furthermore, 10 mM βGP added once during gel preparation was sufficient to induce mineralization with mineral accumulation up to day 15 whereas the speed of the gel contraction decreased. In every condition, cultures expressed high alkaline phosphatase (ALP) levels as early as day 3, which decreased afterwards. These kinetics might explain why the other conditions did not prove favorable to the mineralization process. The model was used to study the influence of blocking gel retraction. Blocking retraction delayed the ALP activity decrease, but had no effect on mineralization. In conclusion, human adult osteoblasts cultured in native collagen gel stopped proliferation and underwent mineralization very early. This model should be used to investigate the influence of effectors on the early stages of culture. Received: 15 October 1997 / Accepted: 1 July 1999     

糖尿病视网膜病变与血清Ⅳ胶原、层粘连蛋白的关系

目的 探讨糖尿病视网膜病变(DR)与血清IV胶原(IVC)、层粘连蛋白(LN)之间的关系。 方法 143例 2型糖尿病患者作为病例组,并依据视网膜病变情况分为三组:无视网膜病变组(NDR)58例,背景期视网膜病变组(BDR)47例,增殖期视网膜病变组(PDR)38例。同时设健康体检者55人为对照组。采用放射免疫法测其血清IVC、LN的含量。所有检测者均测定空腹血糖、糖化血红蛋白、血脂、尿白蛋白排泄率、体重指数,分析病例组血清IVC、LN水平与视网膜病变的关系。结果 (1)血清IV-C水平:三组糖尿病患者明显高于对照组(P<0.01)。病例组间比较,PDR组高于BDR组,BDR组高于NDR组,差异均有非常显著意义(P<0.01)。(2)血清LN水平:BDR组、PDR组高于对照组,差异均有非常显著意义(P<0.01),NDR组与对照组比较,增高不明显,无统计学意义(P>0.05)。病例组间比较,PDR组高于BDR组,BDR组高于NDR组,差异均有非常显著意义(P<0.01)。(3)Logistic多元回归分析显示,血清IVC、LN、病程是DR发病的独立风险因素。结论 血清IVC、LN与DR发生发展密切相关,联合检测血清IVC、LN水平,有助于估计DR病变程度及预后。     

Tissue engineered artificial skin composed of dermis and epidermis

Abstract: We made an artificial skin comprised of a stratified layer of keratinocytes and a dermal matrix with a type I collagen containing fibroblasts. In this work, we showed keratinocyte behavior under primary culture, gel contractions varying with concentration of collagen solution, and cell growth plots in the collagen gel. The optimum behavior of dermal equivalent could be obtained using 3.0 mg/ml collagen solution and attached gel culture. The attached gel culture had a jumping effect of growth factor on cell growth at the lag phase. To develop the artificial skin, 1× 10⁵ cells/cm² of keratinocytes were cultured on the dermal equivalent at air-liquid interface. Finally, to overcome the problem that artificial skin of collagen gel was torn easily during suturing of grafting, we prepared histocompatible collagen mesh and attached the mesh to the bottom of the gel. Cultured artificial skins were successfully grafted onto rats.     

Ultrastructural organization of proteoglycans and fibrillar matrix of the tectorial membrane

The molecular and supramolecular structure of the tectorial membrane (TM) was studied by transmission electron microscopy (TEM). Collagen (type A) fibrils in the TM were found associated with proteoglycans (PGs) and type B fibrils. Most PGs were orthogonally oriented and attached D-periodically to collagen fibrils. Computer averaged projections of PG particles and linear aggregates of PGs in crystalline arrays, stained with Cuprolinic blue, showed an elongated, electron-dense structure 50–65 nm in length and 10 nm in width. Image analysis of type B fibrils showed that they are constructed of globular domains arranged with a periodicity of 12–14 nm. Each globular domain contains two thin ‘arms', extended in opposite directions, which contact the ‘arms' of adjacent fibrils. Numerous type B fibrils were found between collagen fibrils. They are attached to adjacent collagen fibrils by the ‘arms' of their globular domains. An association of type B fibrils and PGs with collagen seems to result in the local ordered arrangement of the TM matrix. A hypothetical model of the TM matrix supramolecular structure is presented.     

吡啶-2,6(1H,3H)二酮生物碱对ADP、AA、Collagen诱导的兔血小板聚集的影响

目的观察吡啶－２，６（１Ｈ，３Ｈ）二酮生物碱（ＳＨ１）对ＡＤＰ、ＡＡ、Ｃｏｌｌａｇｅｎ诱导的兔血小板聚集的影响。方法用比浊法测定了ＳＨ１体外对兔血小板聚集的影响。结果ＳＨ１对３种诱导剂的最大抑制率分别为６２．１６％、４５．２５％、５３．６７％。大剂量组明显加快ＡＤＰ诱导的兔血小板聚集后的解聚速度。ＳＨ１显著延长Ｃｏｌａｇｅｎ的诱导起聚时间。结论ＳＨ１０．８～４．０ｍｍｏｌＬ－１范围内明显抑制ＡＡ、ＡＤＰ、Ｃｏｌａ－ｇｅｎ诱导的兔血小板聚集。其抑制作用有明显的量效关系。其机制待进一步研究。     

藻鳖软肝汤对实验性肝纤维化大鼠作用的研究

目的：研究藻鳖软肝汤抗纤维化的作用。方法：用CCl4复合因素制备大鼠肝纤维化模型，同时用藻鳖软肝汤治疗，用生理盐水作对照，观察其对肝功能及纤维化指标的影响。结果：藻鳖软肝汤对肝纤维化大鼠，有显著降低血清透明质酸（HA）、Ⅲ型前胶原（PCⅢ）、Ⅳ型胶原（Ⅳ-C）；明显改善肝功能的作用。结论：藻鳖软肝汤具有确切的抗纤维化作用。     

重组人Ⅱ型胶原250-270多肽的表达、纯化和鉴定

目的:表达与纯化重组人Ⅱ型胶原250-270多肽(rhCⅡ250-270),鉴定并确认rhCⅡ250-270多肽与预期的相符。方法:在E.coli BL 21中表达rhCⅡ250-270多肽,使用亲和层析法分离纯化。用限制性酶切、聚合酶链式反应(PCR)、基因序列测定、琼脂糖凝胶电泳、聚丙烯酰胺凝胶电泳(SDS-PAGE)和免疫印迹等方法在基因和蛋白水平上对rhCⅡ250-270多肽进行鉴定。结果:纯化的rhCⅡ250-270多肽,大小约43 kD,纯度为89.3%。E coRⅠ和SalⅠ双酶切法和PCR法鉴定测得DNA大小约为500bp和650bp,核苷酸序列测定证实基因DNA序列与设计的完全相符。SDS-PAGE显示rhCⅡ250-270多肽目的蛋白条带的大小约为43 kD,W estern B lotting证实GST融合蛋白上存在CⅡ片段。结论:表达和纯化rhCⅡ250-270多肽与预期的相符,并发现此多肽具有较强的免疫原性。     

压力容量超负荷大鼠模型右心室重塑过程中细胞间质的改变

目的：通过人工套接大鼠右侧颈动静脉，造成左向右分流，导致大鼠右心室压力容量负荷增加，从多个不同层面研究大鼠右心室重塑过程中细胞间质的变化。方法：设4个实验组与4个对照组，每组10只体重、性别相匹配的近交系Wistar大鼠。实验组无菌手术套接大鼠右侧颈总动脉与颈外静脉，造成左向右分流，于术后1、2、4、8周分别测定动物体重(BW)，右心室与左心室加室间隔质量之比［R/(L+S)］及右心室质量与体重之比(RV mg/BW g)；右心室组织切片，普通光镜下观察组织学的改变，并利用计算机形态学分析软件分析细胞与间质的改变；提取右心室心肌组织中mRNA，应用RT PCR法测定Ⅰ、Ⅲ型胶原、纤维结合素Ⅰ基因表达量的变化。对照组手术操作同试验组，唯不套接动静脉，同样条件饲养。结果：术后第1周开始，试验组大鼠右心室压力即明显高于对照组，术后第1、2、4、8周之间相比，无统计学意义。试验组大鼠（RV mg/BW g）在术后8周时有统计学意义（0.64±0.05 vs 0.43±0.03，P＜0.01）; R/(L+S)至第8周时也有类似变化（0.36±0.04 vs 0.21±0.02，P＜0.05 ）；所有试验大鼠均未发生心衰现象，与对照组相比，Ⅰ、Ⅲ型胶原mRNA表达量在第1、4、8周时改变不明显，第2周时有统计学意义(Ⅰ型胶原：0.93±0.18 vs 0.79±0.07，P＜0.05；Ⅲ型胶原：0.43±0.07 vs 0.36±0.07，P＜0.05。平均光密度法)。纤维结合素Ⅰ第1周时即可检测到mRNA表达量升高，与对照组相比有统计学意义（0.26±0.06 vs 0.20±0.05，P＜0.05）；第2、4、8周时与对照相比无统计学差异。结论：①压力容量负荷改变能够引起大鼠右心室的重塑，包括心肌细胞和细胞周围基质，不同的改变可以有不同的时间特征，并和右心室压力有明显相关性；②反映细胞周围基质改变的Ⅰ型胶原、Ⅲ型胶原、纤维结合素Ⅰ基因在改变的早期出现明显改变，说明右心室重塑是机体对外界环境改变积极适应的结果。     

甲心安煎剂对甲状腺素性心脏肥大大鼠心肌胶原含量的影响

目的 探讨甲心安煎剂治疗甲状腺素性心脏肥大的机制。方法将清洁级SD大鼠40只分为4组，即正常组、模型组、甲心安高剂量和低剂量治疗组各10只。正常组与模型组每日灌服纯化水2 mL，高剂量组每日灌服甲心安原液(含生药4 g·mL^-1)，低剂量组灌服甲心安稀释液(将原液加纯化水稀释至含生药2 g·mL^-1)，连续给药10 d。实验第11天取标本检测指标。结果模型组左心室重量及与体重之比均高于正常组(P＜0.01)，心肌胶原含量及 Ⅰ/Ⅲ 胶原比例均较正常组高(P＜0.01)。与之相反，经过甲心安煎剂干预后，治疗组无论低剂量或高剂量，其上述指标均较模型组低(P＜0.01)。结论甲心安煎剂能改善甲状腺素引起的心肌肥厚，降低重构心肌中的胶原含量，并调整优化心肌中 Ⅰ/Ⅲ 胶原比例。