The matrix metalloproteinase inhibitor BB-1101 prevents experimental autoimmune uveoretinitis (EAU)

EAU is characterized by breakdown of the blood-retinal barrier and extravasation of leucocytes into retinal tissue leading to destruction of photoreceptor cells. Matrix metalloproteinases (MMP) have been implicated in trafficking of cells into tissues, but their role in inflammatory eye disease is unclear. A synthetic MMP inhibitor, BB-1101, was administered subcutaneously, from either day 0 or day 7, to Lewis rats challenged with bovine S-antigen to induce EAU. When given up to day 14, BB-1101 reduced the incidence of disease and delayed the day of onset of clinical disease. When administered from day 7 until day 21, EAU was completely abrogated. A quantitative polymerase chain reaction (PCR) assay showed an increase of both matrilysin (MMP-7), neutrophil collagenase (MMP-8) and macrophage metalloproteinase (MMP-12) in retinas from EAU animals compared with naive controls. These enzymes are produced by activated leucocytes and act on components of the basement membrane. These results therefore implicate these MMP as integral to the development of pathology in EAU.     

Addition of fibronectin to alginate matrix improves peripheral nerve regeneration in tissue-engineered conduits

Schwann cell (SC) transplantation has been proposed to encourage peripheral nerve regeneration, but an optimal SC-carrying matrix would be needed. The aim of this study was to characterize how the addition of fibronectin to alginate would affect the outcome of nerve regeneration promoted by Schwann cells embedded in this matrix. Genetically labeled rat SCs were obtained by lacZ gene transduction. SCs were suspended in alginate hydrogel matrix with/without addition of liquid fibronectin, and their viability and growth in the different types of matrices were assessed in vitro by AlamarBlue assay. In vivo assessment of SC transplantation in the matrix was carried out with poly-3-hydroxybutyrate (PHB) conduits to bridge a sciatic nerve gap. The grafted conduits were harvested at 2, 3, and 6 weeks and assessed for the presence of labeled SCs in relation to regrowing axons. The amount and rate of axonal regeneration were assessed by quantitative immunohistochemistry. Addition of fibronectin to alginate hydrogel improved SC viability and growth profile in vitro. X-Gal staining confirmed that SCs transplanted in PHB conduits were viable throughout the time course, and that the labeled SCs were clearly associated with regenerating axons. The regeneration rate was enhanced when liquid fibronectin was added to the alginate matrix. Furthermore, the presence of SCs also enhanced regeneration and there was an additive effect when both SCs and fibronectin were combined with alginate. In conclusion, the addition of fibronectin to alginate hydrogel matrix contributed to improve nerve regeneration, supporting SC viability and augmenting their effect on axonal growth when transplanted in a bioengineered nerve conduit.     

The effect of para-aminomethylbenzoic acid (amben) on peripheral nerve regeneration

Various injuries to the sciatic nerve were modelled in experiments on 60 rats and 27 dogs to study the effect of paraaminomethylbenzoic acid on its regeneration; the efficacy of amben was compared with that of other agents used widely for the treatment of injuries to nerves. It was found that amben acts on the connective tissue of the neural scar and creates favourable conditions for growth of axons from the central to the peripheral stump of the injured nerve and accelerated their maturation.     

物理疗法促进周围神经损伤的修复与再生

目的 探讨物理疗法对受损的周围神经的功能恢复和保护作用。方法 建立Wistar大鼠坐骨神经损伤模型，选用生物频谱照射和红外线照射的方法，观察受损坐骨神经在2周内的恢复状况。结果 经生物频谱照射和红外线照射的坐骨神经纤维与对照组有显著性差异，溃变纤维数量明显减少。结论 实施受损周围神经修复手术后，选用物理疗法作为辅助疗法有助于神经纤维的恢复和保护作用，其中生物频谱照射法效果较好。     

基质金属蛋白酶及其组织抑制因子在左心室机械辅助减负荷模型中的表达

目的 研究基质金属蛋白酶(MMP)及其组织抑制因子(TIMP)在左心室机械辅助减负荷模型中的表达,探讨左心室减负荷后心肌逆向重构的分子机制.方法 结扎Lewis大鼠冠状动脉左前降支诱导心力衰竭,4周后将14只心力衰竭大鼠随机分为心力衰竭组(n=7)与移植组(n=7).将供体移植组心力衰竭大鼠的心脏及右肺移植到受体正常Lewis大鼠的腹部,通过供体的升主动脉与受体的降主动脉吻合.7只正常Lewis大鼠作为正常组.结扎左前降支4周后心脏超声测量3组大鼠心室直径和心肌梗死范围.移植2周后,称取各组大鼠心脏、左心室质量;显微镜观测左心室心肌细胞直径与心肌纤维化程度;采用实时荧光定量PCR检测MMP-1、MMP-9、TIMP-1的mRNA表达及计算MMP-1mRNA/TIMP-1 mRNA的比值.结果 结扎左前降支4周后,心力衰竭组及移植组舒张末直径(LVEDD)较正常组升高、左心室短轴缩短率(LVFS)较正常组下降,而此两组间LVEDD、LVFS及心肌梗死范围比较差异无统计学意义,两组的心力衰竭严重程度差异也无统计学意义.心力衰竭组心脏、左心室质量和左心室心肌细胞直径大于移植组与正常组;移植组心脏、左心室质量、左心室心肌细胞直径接近正常组.心肌纤维化的程度移植组＞心力衰竭组＞正常组[(7.90±2.32)％比(4.20±1.84)％比(1.54±0.31)％,均P＜0.05].心力衰竭组和移植组MMP-1、MMP-9mRNA表达均高于正常组(1.89±0.23、1.32±0.16比0.41±0.01,2.03±0.15、1.50±0.13比0.46+0.01,均P＜0.05),但心力衰竭组与移植组比较差异无统计学意义.心力衰竭组TIMP-1mRNA表达低于正常组与移植组(0.72±0.18比1.21±0.02、1.68±0.21,均P＜0.05);正常组与移植组比较差异无统计学意义.心力衰竭组MMP-1 mRNA/TIMP-1mRNA比值较正常组及移植组明显增高(2.03±0.15比0.30±0.01、0.81±0.11,均P＜0.05);正常组与移植组差异则无统计学意义.结论 左心室减负荷后,心肌逆向重塑的过程伴随着心肌细胞MMP及TIMP水平的改变.     

Characteristics of peripheral nerve regeneration following a second nerve injury and repair

During the process of peripheral nerve regeneration, a single neuron can regenerate and maintain more than one collateral in a regenerative distal stump. Furthermore, some of the new shoots can mature gradually through remyelination and grow into the remote target organ to play a physiological function. Our study found that when neonatal nerve fibers are subjected to a second injury, the regenerative distal stump can regenerate and maintain more than one collateral in the second regenerative distal stump. The neonatal nerve contributed to the functional recovery of the nerve, but the restoration of nerve function was not complete.     

A novel use of genipin-fixed gelatin as extracellular matrix for peripheral nerve regeneration

Application of combining herbal medicine and biomedical material science to nerve regeneration is a new approach. In this study, we describe a novel use of purified genipin, which can be extracted from Gardenia jasminoides Ellis, fixing the gelatin to be an extracellular matrix for peripheral nerve regeneration. A 10-mm gap of rat sciatic nerve was created between the proximal and distal nerve stumps, which were sutured into silicone rubber tubes filled with either the genipin-fixed gelatin or collagen gel. Silicone rubber tubes filled with saline were used as controls. Six weeks after implantation, regeneration across the nerve gaps occurred in 80 and 90% of the animals from the groups of genipin-fixed gelatin and collagen, respectively, whereas only 30% in the control group. Large numbers of myelinated axons were also seen in the genipin-fixed gelatin (5104 +/- 3278) and the collagen groups (8063 +/- 1807). These findings indicated that the genipin-fixed gelatin could be an acceptable extracellular matrix for nerve regeneration.     

A peptidomimetic inhibitor of matrix metalloproteinases containing a tetherable linker group

Successful wound repair and normal turnover of the extracellular matrix relies on a balance between matrix metalloproteinases (MMPs) and their natural tissue inhibitor of metalloproteinases (TIMPs). When overexpression of MMPs and abnormally high levels of activation or low expression of TIMPs are encountered, excessive degradation of connective tissue and the formation of chronic ulcers can occur. One strategy to rebalance MMPs and TIMPs is to use inhibitors. We have designed a synthetic pseudopeptide inhibitor with an amine linker group based on a known high-affinity peptidomimetic MMP inhibitor and have demonstrated inhibition of MMP-1, -2, -3, and -9 activity in standard solutions. The inhibitor was also tethered to a polyethylene glycol hydrogel using a facile reaction between the linker unit on the inhibitor and the hydrogel precursors. After tethering, we observed inhibition of the MMPs although there was an increase in the IC??s that was attributed to poor diffusion of the MMPs into the hydrogels, reduced activity of the tethered inhibitor, or incomplete incorporation of the inhibitor into the hydrogels. When the tethered inhibitors were tested against chronic wound fluid, we observed partial inhibition in proteolytic activity suggesting this approach may prove useful in rebalancing MMPs within chronic wounds.     

MMP-9/TIMP-1表达在糖尿病鼠皮肤伤口愈合过程中的变化及意义初探

目的：观察基质金属蛋白酶-9（MMP-9）、组织金属蛋白酶抑制剂-1（TIMP-1）的表达和MMP-9/TIMP-1比值在糖尿病组和正常组大鼠皮肤伤口愈合过程中不同时点表达的动态变化，探讨其可能的作用机制。 方法:糖尿病大鼠形成6周后行皮肤伤口造模，采用HE染色、Masson染色和免疫组织化学方法评估伤口形成后3、7、14 d伤口组织的再上皮化、炎症细胞浸润、肉芽组织厚度、新生血管形成和胶原纤维密度的情况；通过逆转录-聚合酶链反应(RT-PCR)和Western印迹检测术后不同时点MMP-9、TIMP-1在伤口组织中的表达情况。结果:糖尿病大鼠伤口愈合明显迟缓。术后第3 d两组间胶原纤维、肉芽组织、新生血管和再上皮化没有差异，术后第7 d糖尿病组以上指标得分均低于正常组，第14 d这种趋势更加明显；而第3 d至14 d，糖尿病组的单核巨噬细胞浸润得分均低于正常组。术后第3 d两组MMP-9表达均达高峰，第7、14 d呈逐渐下降趋势，糖尿病组MMP-9表达水平在各时点均高于正常组；术后第3 d两组TIMP-1表达均达高峰，第7、14 d呈逐渐下降趋势，糖尿病组TIMP-1表达水平在各时点均低于正常组；正常组MMP-9/TIMP-1蛋白水平比值始终维持在一个动态平衡的稳定水平，而糖尿病组却长期处于高水平状态。结论:异常的胶原产生、新生血管重建、炎症反应、再上皮化、肉芽形成可能是糖尿病鼠创面愈合减慢的组织病理学基础；皮肤组织MMP-9/TIMP-1的平衡性改变可能是这种组织病理学异常的重要原因之一。     

Promoting peripheral nerve regeneration with biodegradable poly (DL-lactic acid) films

Regeneration and repair of peripheral nerve injury has always been a major problem in the clinic. The conventional technique based on suturing the nerve ends to each other coupled with the implantation of nerve conduits outside is associated with postoperative adhesions and scar problems. Recently, a novel biodegradable poly (DL-lactic acid) (PDLLA) film has been introduced. This novel anti-adhesion film has a porous structure with better mechanical properties, better flexibility, and more controllable degradation as compared to traditional non-porous nerve conduits. However, little is known about the effects of such PDLLA films on regeneration and repair of peripheral nerve injury in vivo. In this study, we evaluated the effects of PDLLA films implantation after sciatic nerve transection and anastomosis on subsequent sciatic nerve regeneration in vivo, using a rat sciatic nerve injury model. Sciatic nerve transection surgery coupled with direct suturing only, suturing and wrapping with traditional nerve conduits, or suturing and wrapping with PDLLA films was performed on adult Wistar rats. The additional wrapping with PDLLA films inhibited the nerve adhesion after 12 weeks recovery from surgery. It also increased the compound muscle action potentials and tibialis and gastrocnemius muscle wet weight ratio following 8 weeks recovery from surgery. Regenerated nerve fibers were relatively straight and the aligned structure was complete in rats with implantations of PDLLA films. The results suggested that PDLLA films can improve the nutritional status in the muscles innervated by the damaged nerves and promote nerve regeneration in vivo.     

周围神经趋化性再生研究新进展

周围神经损伤后修复及功能重建一直是临床治疗的难题.现从周围神经趋化性再生的概念,感觉与运动神经元自身差异、远侧端神经、施万细胞、成纤维细胞以及轴突导向因子等方面阐述了目前周围神经趋化性再生的研究进展,为将来开发更好的工程化神经组织,促进神经功能良好的恢复提供基础知识.     

周围神经再生中人工再生管道的研究进展

周围神经损伤造成的长段神经缺损的临床修复一直是临床工作中的一个难题。随着对神经再生理论认识的深入 ,应用人工再生管道做桥接物 ,引导再生轴突长向靶器官已取得了一定的进展。本文对各种人工再生管道的特点以及在神经再生中的作用进行了综述     

X-irradiation impairs regeneration of peripheral nerve across a gap

Summary The effects of X-irradiation on the regeneration of peripheral nerve across a gap were studied in the mouse. The right sciatic nerve was transected and 3 days later a 20-Gy dose of X-rays was administered to the hind limb, which was shielded so that the irradiation affected either the proximal, the distal or both parts of the nerve. Within a few hours of irradiation, the proximal and distal nerve stumps were inserted into a polythene tube within which they were separated by a 5-mm gap. After 1 or 2 months the sciatic nerves were processed for examination by light and electron microscopy. Irradiation affected axonal growth, differentiation of Schwann cells and formation of a perineurium. These effects were most marked when both the proximal and distal stumps had been exposed to X-rays. At 2 months there were fewer axons in the irradiated than in control nerves (P<0.01), but all of the larger axons which had regenerated were myelinated, albeit more thinly than in the controls. The changes in the pattern of regeneration in the irradiated nerves are interpreted as being largely due to radiation damage to Schwann cells.     

Extracellular matrix of human amnion manufactured into tubes as conduits for peripheral nerve regeneration

The human amnion consists of the epithelial cell layer and underlying connective tissue. After removing the epithelial cells, the resulting acellular connective tissue matrix was manufactured into thin dry sheets called amnion matrix sheets. The sheets were further processed into tubes, amnion matrix tubes (AMTs), of varying diameters, with the walls of varying numbers of amnion matrix sheets with or without a gelatin coating. The AMTs were implanted into rat sciatic nerves. Regenerating nerves extended in bundles through tubes of 1-2 mm in diameter and further elongated into host distal nerves 1-3 weeks after implantation. Morphometrical analysis of the regenerated nerve cable at the middle of each amnion matrix tube 3 weeks after implantation was performed. The average numbers of myelinated axons were almost the same (ca. 80-112/10(4) microm(2)) in AMTs of 1-2 mm in diameter, as in the normal sciatic nerve (ca. 95/10(4) microm(2)). No myelinated fibers were found in AMTs composed of multiple thin tubes of 0.2 mm in diameter. The myelinated axons were thinner in implanted tubes than those in the normal sciatic nerve. The rate of occurrences of myelinated axons less than 4 microm in diameter was significantly higher in the AMTs, whereas axons in the normal sciatic nerve were diverse in distribution, with the highest population at 8-12 microm in diameter. Reinnervation to the gastrocnemius muscle was demonstrated electrophysiologically 9 months after implantation. It was concluded that the extracellular matrix sheet from the human amnion is an effective conduit material for peripheral nerve regeneration.     

Role of matrix metalloproteinases and their tissue inhibitor of metalloproteinases in myxomatous change of cardiac floppy valves

To clarify the underlying cause of myxomatous changes in cardiac floppy valves, the expression of the matrix metalloproteinases (MMP) and the tissue inhibitors of metalloproteinases (TIMP) was investigated in cardiac valves. Valves were obtained from nine patients with floppy valves, from 13 patients with other valvular disease types, and from four patients with normal valves. Immunohistochemical analyses for MMP-2, MMP-9, TIMP-1, and TIMP-2, and gelatin zymography for MMP-2 and MMP-9 were performed. Compared with the spongiosa of normal valves, the myxomatous area of floppy valves had stronger immunohistochemical reaction to MMP-2 and MMP-9, and weaker reaction to TIMP-2. Activated MMP-2 and MMP-9 were detected in eight out of nine cases of floppy valves. Activated MMP-2 was detected at low levels in two cases of normal valves showing mild expansion of the spongiosa without macroscopic floppiness. The ratio of active/total MMP-2 and MMP-9 increased in floppy valves compared with normal valves. These results suggest that the imbalance between MMP and TIMP and the increased activity of MMP-2 and MMP-9 may correlate with myxomatous changes observed in floppy valves. Valves with a slight myxomatous change and activated MMP-2 may develop into floppy valves with increases in the activity of MMP.     

Retinal and peripheral nerve toxicity induced by the administration of a pan-cyclin dependent kinase (cdk) inhibitor in mice

Cyclin-dependent kinases (cdks) play a crucial role in cell cycle regulation and are considered promising targets for cancer therapy. Intravenous administration of AG-012986, a pan-cyclin-dependent kinase inhibitor (cdk(i)), resulted in unexpected retinal and peripheral nerve toxicity in mice. AG-012986 was administered daily to CD-1 or B6C3F1 mice for 5 consecutive days. Mice were euthanized 24 h after the last dose (study day 6) or after a 21-day post-dose period (study day 26). Compound related microscopic findings were seen in the sciatic nerves (axonal degeneration) of both strains and in the retina (retinal degeneration/atrophy) of CD-1 mice only after the post-dose period. Although retinal degeneration/atrophy was not detected by routine histology in mice euthanized on day 6, apoptotic retinal cells were evident at this time using TUNEL assay. To our knowledge retinal or peripheral nerve toxicity secondary to the administration of cdk(i)s has not been previously reported. Although the pathogenesis of these lesions is unclear, the toxicities may reflect the unique profile of cdk inhibition, off-target kinase inhibition or receptor binding, or metabolism/distribution properties of AG-012986. Multi-targeted-inhibitors may interfere with cdks and other kinases involved in a wide range of functions other than cell cycle regulation, which could result in unexpected toxicities that may hinder their clinical applications.     

神经生长因子及其受体在周围神经损伤再生中的作用机制

神经生长因子(nerve growth factor,NGF)作为最早发现的能够促进神经再生的神经营养因子(neurotrophin factors,NTFs),与其不同受体的相互作用对神经往往会产生促凋亡或抑制凋亡、维持生长、诱导再生、促进分化等两种相反的结局。对这些作用机制的研究有助于对周围神经损伤再生     

Evaluation of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) conduits for peripheral nerve regeneration

Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) was investigated for possible application in repairing damaged nerves. Porous nerve conduits with both uniform wall porosity and non-uniform wall porosity were prepared using a particle leaching method. Adult Sprague-Dawley (SD) rats weighing 200-250 g were used as the animal model. The conduits were employed to bridge the 10mm defects in the sciatic nerve of the Sprague-Dawley (SD) rats. Mechanical tests showed that the PHBHHx nerve conduits had proper mechanical properties including maximal loads of 3.1N and 1.3N for the conduits with non-uniform wall porosity and with uniform wall porosity, respectively, and maximal stresses of 2.3 MPa and 0.94 MPa for the conduits with non-uniform wall porosity and with uniform wall porosity, respectively. At the same time, both types of conduits were permeable to three compounds tested including glucose, lysozyme and bovine serum albumin, indicating the suitability of the conduits for free exchanges of nutrients. Compound Muscle Action Potentials (CMAPs) were clearly observed in both types of the PHBHHx nerve conduits after 1 month of implantation, indicating a rapid functional recovery for the disrupted nerves. The results of histological sections demonstrated that the internal sides of the conduits with non-uniform wall porosity were compact enough to prevent the connective tissues from ingrowth penetration. After implantation for 3 months in the rats, the conduits with uniform wall porosity and those with non-uniform wall porosity lost 24% and 20% of their original weight average molecular weights, respectively. Combined with the strong mechanical properties, good nerve regeneration ability and non-toxicity of its degradation products, PHBHHx nerve conduits can be developed into a useful material to repair nerve damage.