聚己内酯在组织工程中的应用进展

聚己内酯(PCL)以其具有的良好生物相容性及其力学特点,在组织工程领域已经成为主要的生物支架材料之一。利用生物支架材料,组织工程的目的是对组织、器官的丧失或功能障碍进行修复与重建。本文综述了对生物支架材料聚己内酯(PCL)的研究进展以及其在组织工程中的应用。     

A model predicting delivery of saquinavir in nanoparticles to human monocyte/macrophage (Mo/Mac) cells

Modeling the influence of a technology such as nanoparticle systems on drug delivery is beneficial in rational formulation design. While there are many studies showing drug delivery enhancement by nanoparticles, the literature provides little guidance regarding when nanoparticles are useful for delivery of a given drug. A model was developed predicting intracellular drug concentration in cultured cells dosed with nanoparticles. The model considered drug release from nanoparticles as well as drug and nanoparticle uptake by the cells as the key system processes. Mathematical expressions for these key processes were determined using experiments in which each process occurred in isolation. In these experiments, intracellular delivery of saquinavir, a low solubility drug dosed as a formulation of poly(ethylene oxide)-modified poly(epsilon- caprolactone) (PEO-PCL) nanoparticles, was studied in THP-1 human monocyte/macrophage (Mo/Mac) cells. The model accurately predicted the enhancement in intracellular concentration when drug was administered in nanoparticles compared to aqueous solution. This simple model highlights the importance of relative kinetics of nanoparticle uptake and drug release in determining overall enhancement of intracellular drug concentration when dosing with nanoparticles.     

A coarse-grained model for PCL: conformation,self-assembly of MePEG-b-PCL amphiphilic diblock copolymers

Poly-ε-caprolactone (PCL) is a biodegradable hydrophobic polyester that has been widely used in medical devices, tissue engineering and nanoparticle-based drug delivery. Coarse-grained molecular dynamics (CGMD) has been employed to study and gain insights into the conformational, structural and self-assembly behaviour of polymers, lipids and amphiphilic macromolecules. In this work, we developed a model for PCL within the framework of the MARTINI coarse-grained force field. The non-bonded interactions were based on the existing MARTINI bead types, while the bonded interactions were mapped onto a PCL rendition obtained from atomistic simulations. The model accurately reproduces the structural and dynamic properties of the PCL homopolymer and shows very reasonable temperature and solvent transferability. We also studied self-assembly of MePEG-b-PCL linear diblock copolymers using an existing MARTINI model for MePEG (Methoxy Polyethylene glycol), by analysing the critical micelle concentration (CMC), as well as the shape, size and morphology of the nano-polymeric micelles. We obtained excellent agreement of the CMC, while the size was under-predicted compared to experimental data. This robust model paves the way for CGMD modelling of PCL and serves as a starting point for future designs of PCL-related polymeric systems .     

Nano carriers that enable co-delivery of chemotherapy and RNAi agents for treatment of drug-resistant cancers

Tumor cells exhibit drug resistant phenotypes that decrease the efficacy of chemotherapeutic treatments. The drug resistance has a genetic basis that is caused by an abnormal gene expression. There are several types of drug resistance: efflux pumps reducing the cellular concentration of the drug, alterations in membrane lipids that reduce cellular uptake, increased or altered drug targets, metabolic alteration of the drug, inhibition of apoptosis, repair of the damaged DNA, and alteration of the cell cycle checkpoints ( and ). siRNA is used to silence the drug resistant phenotype and prevent this drug resistance response. Of the listed types of drug resistance, pump-type resistance (e.g., high expression of ATP-binding cassette transporter proteins such as P-glycoproteins (Pgp; also known as multi-drug resistance protein 1 or MDR1, encoded by the ATP-Binding Cassette Sub-Family B Member 1 (ABCB1) gene)) and apoptosis inhibition (e.g., expression of anti-apoptotic proteins such as Bcl-2) are the most frequently targeted for gene silencing. The co-delivery of siRNA and chemotherapeutic drugs has a synergistic effect, but many of the current projects do not control the drug release from the nanocarrier. This means that the drug payload is released before the drug resistance proteins have degraded and the drug resistance phenotype has been silenced. Current research focuses on cross-linking the carrier's polymers to prevent premature drug release, but these carriers still rely on environmental cues to release the drug payload, and the drug may be released too early. In this review, we studied the release kinetics of siRNA and chemotherapeutic drugs from a broad range of carriers. We also give examples of carriers used to co-deliver siRNA and drugs to drug-resistant tumor cells, and we examine how modifications to the carrier affect the delivery. Lastly, we give our recommendations for the future directions of the co-delivery of siRNA and chemotherapeutic drug treatments.     

Polygonatum cyrtonema lectin induces murine fibrosarcoma L929 cell apoptosis and autophagy via blocking Ras–Raf and PI3K–Akt signaling pathways

Polygonatum cyrtonema lectin (PCL), a mannose/sialic acid-binding lectin, has been reported to display remarkable anti-proliferative and apoptosis-inducing activities toward a variety of cancer cells; however, the precise molecular mechanisms by which PCL induces cancer cell death are still elusive. In the current study, we found that PCL could induce apoptosis and autophagy in murine fibrosarcoma L929 cells. Subsequently, we demonstrated that inhibition of Ras could promote L929 cell death, suggesting that Ras–Raf signaling pathway plays the key negative regulator in PCL-induced apoptosis. And, we showed that Ras-Raf signaling pathway was also involved in PCL-induced autophagy as the negative regulator. In addition, we found that class I phosphatidylinositol 3-kinase (PI3K)–Akt signaling pathway could play the negative regulator in PCL-induced apoptosis and autophagy. Taken together, these results demonstrate that PCL induces murine fibrosarcoma L929 cell apoptosis and autophagy via blocking Ras-Raf and PI3K–Akt signaling pathways.     

3D打印PCL/β-TCP可降解椎间融合器的体外降解及生物力学研究

目的:研究以质量配比为5:5的聚己内酯(PCL)与磷酸三钙(β-TCP)为原材料,应用3D打印技术制备的的可降解的颈椎椎间融合器在体外的降解特性,为临床应用提供理论依据。方法:将制备好的融合器浸泡于模拟体液中,置于37℃温箱,每2周更换浸泡液,按浸泡时间的不同分为六组:分别为空白对照组、2周、4周、12周、26周、52周组。每组浸泡前后经室温真空干燥后用同一天平测量质量,计算失重质量及失重率,应用凝胶渗透色谱仪分析各组融合器中PCL的分子量变化,并应用INSTRON万能试验机进行抗压强度力学测试。空白对照组为样本室温密闭容器放置,在初始称重并检测分子量及抗压强度测试,52周后计算失重率、检测分子量及抗压强度。结果:该种可降解椎间融合器初始抗压强度达到(23.21±2.28)MPa,在体外降解52周后其抗压强度下降不明显,为(18.99±0.49)MPa(P>0.05);其在体外可缓慢降解,52周后失重率约9.23%(P<0.05),其中PCL分子量从初始的10万左右降至7万左右(P<0.05)。结论:该种可降解椎间融合器抗压力学强度适中且能长时间维持,符合临床应用要求,其在体外可缓慢降解,评估其在生物体内的降解吸收特性较好,在人体椎间融合手术中应用的可行性及有效性较高。     

兔后交叉韧带断裂后外侧胫骨平台退变的组织学研究

目的：探讨兔后交叉韧带（Posterior cruciate ligament,PCL）断裂对外侧胫骨平台组织学的影响。方法：48只家兔膝关节随机配对为实验侧和对照侧造模,造模后第4、8、16、24周各随机处死12只,行外侧胫骨平台大体观察、HE染色、免疫组化检测基质金属蛋白酶13（matrix metalloproteinase-13,MMP-13）、基质金属蛋白酶抑制剂1（Tisse inhibitor-1 of matrix metalloproteinasel,TIMP-1）表达。结果：①大体观察,随时间延长,实验组外侧胫骨平台软骨出现磨损,呈灰黄色,弹性差,骨赘形成。②组织学观察,随时间延长,胫骨平台软骨纤维化,细胞排列紊乱,簇聚细胞出现频率增加。⑧实验组MMP-13、TIMP—1表达均高于对照组,有显著性差异。P〈0．05。④实验组MMP-13、TIMP-1表达阳性率第4、8、16周逐渐升高,24周下降,各组比较有显著性差异,P〈0．05。结论：①兔膝关节PCL断裂会引起外侧胫骨平台软骨退行性变,且该退变随着时间的推移逐渐加重。②MMP-13与TIMP-1在PCL断裂膝关节外侧胫骨平台中的表达呈现先高后低的变化规律,造成MMP-13与T1MP-1的失衡,加速软骨退变。⑨MMP-13与T／MP-1表达增高提示MMP-13与TIMP—1可能参与了PCL断裂后外侧胫骨平台软骨的退变过程。     

酵母蛋白质YJL084c的磷酸化分析

PCL6、PCL7(PAP1)和PHO80为酵母蛋白激酶PHO85的细胞周期蛋白因子 ,同属于PHO80亚类 ,它们在蛋白质序列上有较高的同源性 ,彼此在功能上有一定程度的重叠。YLR190w为先前鉴定的PCL7 PHO85的一个底物 ,根据BLAST比较 ,YJL0 84c与YJLR190w在一段区域内有一定的同源性 ,并且根据已公布公共数据库 ,YJL0 84c是PCL6的一个结合蛋白。利用双杂交系统分析了YJL0 84c与这三个细胞周期蛋白因子之间的相互作用 ,表明PCL7也可以结合YJL0 84c。利用免疫共沉淀证实它们在体内的相互作用 ;通过体外GST沉降分析 ,验证它们的体外相互作用。YJL0 84c的体外翻译产物可以被PCL7 PHO85复合物磷酸化 ,进一步分别表达纯化YJL0 84c的氨基末端、中间和羧端三部分的GST融合蛋白片段 ,PCL7 PHO85复合物可以磷酸化其中间部分 ,而对N末端和C末端则未表现出磷酸化。以该中间片段蛋白质为底物 ,进一步研究高低磷条件对其磷酸化的影响。PCL7 PHO85对YJL0 84c的磷酸化受到无机磷条件的明显影响 :高磷条件下 ,磷酸化程度高 ;而低磷条件下磷酸化程度低。有意思的是 ,PCL6 PHO85免疫沉淀复合物也表现出同样的磷酸激酶特征。于是分析PHO81与这三个细胞周期因子之间相互作用。此外 ,还构建了Yjl0 84c的缺失株 ,分析了缺失的可能影响。     

Preparation of electrospun polycaprolactone nanofiber mats loaded with microalgal extracts

Sustainable, ecological, and biocompatible materials are emerging for the development of novel components for tissue engineering. Microalgae being one of the unique organisms on Earth to provide various novel compounds with certain bioactivities are also a good source for the development of novel tissue scaffold materials. In this study, electrospinning technique was utilized to fabricate nanofibers from polycaprolactone loaded with microalgal extracts obtained from Haematococcus pluvialis (vegetative and carotenoid producing form) and Chlorella vulgaris. The FTIR results showed that, blending microalgae with polycaprolactone give unique bands rooted from microalgae and polycaprolactone structure. The samples were not diversified from each other, however stable bands were observed. SEM analysis revealed a uniform fiber fabrication with an average diameter of 810 ± 55 nm independent from microalgal extracts. MTT assay was done on HUVEC cell lines and results showed that nanofiber mats helped cell proliferation with extended time. Biodegradation resulted with mineral accumulation on the surface of same samples however the fiber degradation was uniform. With slow but stable biodegradation characteristics, microalgal extract loaded nanofiber mats holds great potential to be novel tissue scaffold material.