复合三联抗结核药聚乳酸-羟基乙酸缓释微球体内缓释实验研究

目的 :观察载异烟肼(H)、利福平(R)、吡嗪酰胺(Z)复合抗结核药/聚乳酸-羟基乙酸共聚物缓释微球在大鼠体内的缓释特性。方法:选取SD雄性成年大鼠84只,随机分成A、B、C三组,分别设为载药微球组、空白微球组、空白组,于术后1d、3d、1周、2周、4周、6周、8周时分别处死各组4只大鼠,处死时取微球周边1cm肌肉组织和腹腔静脉血5ml,应用高效液相色谱法检测肌肉组织和血清中三种药物浓度;在1周、4周时检测肝、肾功能,留取肝、肾组织观察其组织病理学变化。结果:术后3d时A组中肌肉和血浆中HRZ的药物浓度达到最高,1周后药物的浓度趋于稳定;8周时肌肉组织中HRZ的浓度分别为0.56、0.63、1.51μg/g,均达到了各自的10倍最低有效抑菌浓度,血浆中HRZ浓度分别为0.112、0.046、0.189μg/ml,肌肉中药物浓度和血浆中药物浓度行配对t检验,差异有统计学意义(P0.05);B、C两组肌肉及血浆中均未检测出HRZ。在1、4周时,对三组大鼠肝、肾功能相关指标进行检测,A与C、A与B、B与C组间两两比较t检验,肝、肾功能各项指标在各检测点均无统计学差异(P0.05);A、B、C三组大鼠肝、肾组织病理学检查未见明显损伤。结论:HRZ/PLGA微球具有缓慢、平稳释放药物的特性,具有良好的组织生物相容性,可直接植入体内实现局部给药和缓释长程治疗的双重效果。     

盐酸环丙沙星聚乳酸-羟基乙酸共聚物缓释微球在Gustilo Ⅱ型开放性骨折一期内固定辅助治疗中的应用

目的 制备具有良好降解性及缓释效果的负载盐酸环丙沙星(CIP)的聚乳酸-羟基乙酸共聚物(PLGA)微球(CIP-PLGA-MS),观察其在Gustilo Ⅱ型开放性骨折一期内固定辅助治疗中的作用.方法 采用乳化溶剂挥发法制备微球,检测微球表面形态、产率、载药量、包封率、体外释药曲线等.建立SD大鼠股骨金黄色葡萄球菌(ATCC25923)感染性Gustilo Ⅱ型开放性骨折动物模型,共36只并随机分成对照组A和实验组B,每组18只.感染2h后行清创缝合克氏针髓内固定术,分别植入空白微球和载药微球于大鼠骨折断端.28d后通过X线、病原微生物学评估患肢是否感染.结果 成功制备具有良好缓释性能的CIP-PLGA-MS.微球粒径集中分布于30～100μm范围.产率、载药量、包封率分别达71.37%、4.82%、13.75%.微球24h内突释效应明显,28d累积释放率达71.8%.实验组大鼠感染治愈率为94.44%,对照组为61.11%,差异有统计学意义(P<0.05).结论 CIP-PLGA-MS能够有效辅助降低Gustilo Ⅱ型开放性骨折一期内固定治疗的感染率.

Abstract：

Objective The aim of this study was to prepare poly (D, L-lactide-co-glycolide) (PLGA) biodegradable microspheres loaded with Ciprofloxacin (CIP-PLGA-MS) and to evaluate its adjuvant efficiency for the internal fixation treatment of Gustilo Ⅱ type open fracture. Methods CIP-PLGA-MS was prepared by the double emulsion solvent evaporation method. The microsphere size, morphological characteristics, production yield, drug content, encapsulation efficiency, in vitro release had been detected. The model of Gustilo Ⅱ type open fracture infected with Staphylococcus aureus (ATCC25923) were created in 36 rats which were divided into group A (control group) and group B (experimental group). Sterilized blank microspheres and CIP-PLGA-MS were implanted after 2h of infection in the Femur fracture site of rats in group A and group B respectively after debridement. After 28 days of treatment, the rats were analyzed with X ray and microbiological assay. Results CIP-PLGA-MS between the size ranges of 30-100 μm were obtained. The production yields, drug content and encapsulation efficiencies were 71.37%, 4.82% and 13.75% respectively. In vitro drug release studies shown that these microspheres had significant burst release and their 28 days drug cumulative release rate was up to 71.8%. Based on the in vivo data, cure rate of the rats implanted with CIP-PLGA-MS and empty microspheres were 94.44% and 61.11% respectively (P<0.05). Conclusion CIP-PLGA-MS were found to be effective for the treatment of Gustilo Ⅱ type open fracture in an animal experimental model. Therefore, these microspheres may be potentially useful in clinical medicine.     

酸性可调的聚乳酸-羟基乙酸共聚物微球的制备

目的制备具有酸性自中和能力的聚乳酸-羟基乙酸共聚物[Poly(lactic-co-glycolic acid),PLGA]微球,用于可注射组织工程支架材料或药物释放。方法用二次乳化的方法,将具有缓冲能力的三聚磷酸盐(TPP)包埋于PLGA微球内,制备出PLGA/TPP的复合微球。结果PLGA与TPP以64:1的摩尔比混合时,所制备的PLGA/TPP微球在降解过程中能很好地维持pH值中性,在降解28 d后周围pH值仍为6.93,远高于同样条件下单纯PLGA降解时周围的pH值6.66(P<0.05)。TPP盐颗粒的量对PLGA微球的降解影响很大,当TPP的量增加到12:1时,降解时的酸性要比单纯PLGA微球更为严重,在降解28 d后的pH值低于纯的PLGA微球,仅为6.35(P<0.05)。结论具有缓冲能力的TPP的适量加入,能够有效地调节PLGA微球在降解过程中所产生的酸,从而缓解周围环境pH值下降的问题,但当TPP的量超过一定值时,反而加快PLGA微球的降解。     

复合三联抗结核药聚乳酸-羟基乙酸缓释微球的制备及体外释药特性

目的 :制备复合异烟肼(H)、利福平(R)、吡嗪酰胺(Z)的聚乳酸-羟基乙酸(HRZ/PLGA)缓释微球,观察其理化性质和体外缓释特性。方法:以PLGA(450mg)为载体,避光条件下称取H(40mg)、R(60mg)、Z(125mg),采用复乳-溶剂挥发法制备HRZ/PLGA缓释微球,应用扫描电镜观察微球的形态特征;应用高效液相色谱法(HPLC)测定其载药量、包封率;采用溶出法、HPLC于3h、6h、12h、1d、2d、3d、6d、9d、12d、15d、20d、25d、30d、40d、50d测定H、R、Z三种药物的浓度,观察其是否均大于10倍最低抑菌浓度(MIC),计算其日均释药率、累计释药率。结果:HRZ/PLGA微球在电镜下观察呈圆球形,平均粒径为10.3±4.7μm;H、R、Z三种药物的载药量分别为(18.02±0.36)%、(22.46±0.24)%、(21.68±0.37)%,包封率分别为(54.79±1.13)%、(72.35±0.39)%、(67.21±0.68)%;体外缓释试验显示微球缓释前12d左右,三种药物的累计缓释度均超过了50%,日均释药率分别为5.05%、4.89%、6.86%;第12天后三药的缓释基本趋于稳定,日均释药率分别为0.17%、0.26%、0.16%;三种药物缓释到50d时均大于10倍MIC。结论:HRZ/PLGA微球具有优良的载药及药物缓释效果,是一种理想的复合抗结核药物缓释系统。     

含聚乳酸-羟基乙酸共聚物的新型磷酸钙骨水泥体内降解性能研究

目的探讨含聚乳酸-羟基乙酸共聚物(poly lactic-co-glycolic acid,PLGA)的新型磷酸钙骨水泥(calcium phosphate cement,CPC)(CPC/PLGA)体内降解性能,为临床试验奠定基础。方法按照45%磷酸氢钙、45%部分结晶磷酸钙、10%PLGA比例,制备CPC/PLGA。健康成年新西兰兔32只,体重2.2～3.0 kg,雌雄各半;随机分为CPC/PLGA组(实验组,n=17)及CPC组(对照组,n=15)。两组实验动物制备双侧股骨内侧髁直径4.5 mm、深1.5 cm骨缺损模型,右侧骨缺损分别采用CPC/PLGA及CPC修复,左侧不作处理作为空白对照。术后观察实验动物一般情况,术后2、4、8、16、24周两组取材行组织学观察、骨形态计量学分析,术后8周及16周实验组取材行扫描电镜观察。结果实验动物均存活至实验结束。组织学观察显示,随时间延长,实验组CPC/PLGA逐渐降解,并有新生骨小梁从边缘长入其中,并且增粗、增长,24周时材料基本降解,被新生骨小梁取代;对照组CPC降解明显较实验组延迟。实验组术后总骨组织含量百分比为44.9%±23.7%,显著高于对照组的25.7%±10.9%(t=3.302,P=0.001);实验组术后4周骨组织含量百分比与对照组比较,差异无统计学意义(P>0.05),8、16、24周均显著高于对照组,差异有统计学意义(P<0.05)。扫描电镜观察结果显示,实验组术后8周CPC/PLGA降解后形成孔径为100～300μm孔隙;随着时间延长,16周时新生骨小梁长入孔隙内,并与残余骨水泥牢固结合。结论 CPC/PLGA植入兔体内后具有良好的降解性能,有望成为一种良好骨移植材料。     

聚乳酸-聚羟基乙酸神经导管和骨髓间充质干细胞构建组织工程神经

[目的]用聚乳酸-聚羟基乙酸共聚物(poly lactide-co-glycolide acid,PLGA)为原料制备新型神经导管,同时对兔骨髓间充质干细胞与PLGA构建组织工程神经的可行性进行观察.[方法]以聚乳酸-聚羟基乙酸共聚物和壳寡糖为原料,采用静电纺丝工艺制备中空的PLGA神经导管.通过扫描电镜观察材料的微观结构,排水法测定材料的孔隙率.将兔的骨髓间充质干细胞(BMSCs)分离培养后与导管共培养,扫描电镜观察细胞在材料上的生长粘附情况,MTT方法检测细胞在材料上的增殖活性.[结果]PLGA神经导管管壁具有疏松多孔结构,管壁纤维直径为18 μm左右,孔隙率为85.4%±1.6%,MTT结果显示导管无细胞毒性.兔骨髓间充质干细胞在导管表面生长良好.[结论]PLGA神经导管具有良好的孔隙率,生物相容性好,是构建组织工程神经的良好材料.     

3D打印聚乳酸-羟基乙酸共聚物数字化仿生组织工程骨支架修复兔股骨干长节段骨缺损研究

目的:探讨3D打印聚乳酸-羟基乙酸共聚物(PLGA)数字化仿生组织工程骨支架对兔股骨干长节段骨缺损的修复效果。方法:取19只新西兰大白兔,1只用于3D打印PLGA数字化仿生组织工程骨支架制备,18只制备股骨干长节段骨缺损模型,分为自体骨移植组(A组)、传统支架组(B组)、组织工程骨支架组(C组)各6只。在术后4、8、1...     

聚乳酸羟基乙酸-泊洛沙姆纳米微粒作为siRNA载体的可行性

目的 探讨聚乳酸羟基乙酸-泊洛沙姆(PLGA-Poloxamer)纳米微粒作为siRNA载体的可行性.方法 乳剂溶解扩散法制备PLGA-Poloxarner纳米微粒,观察纳米微粒的物理特征,探讨不同制备条件对纳米微粒物理特征的影响,测定其对含siRNA片段的质粒DNA的包裹效率,检测释放的质粒DNA的结构稳定性,验证纳米微粒对质粒DNA的保护作用,测定其作为载体的基因转染效率.结果 PLGA-Poloxamer纳米微粒呈球形,粒径约为(210.1±24.3)nm,zeta电位为(-0.43 ±1.43)mV,包裹效率为31%.该微粒对质粒DNA有保护作用,释放的质粒DNA结构稳定,转染效率达28%.结论 PLGA-Poloxamer纳米微粒有望成为较理想的siRNA载体.     

聚乳酸/聚羟基乙酸共聚物网管支架体外预血管化及体内植入的实验研究

目的研究预血管化对含网管的多孔可降解聚乳酸/聚羟基乙酸共聚物(polylacticl/glycolicacidcopolymer,PLGA)支架血管化的影响。方法将含网管的多孔可降解PLGA支架由小鼠微血管内皮细胞预血管化,分为体外预血管化组(A组)和单纯支架组(B组)。将两组支架植入12只雌性NIH小鼠肠系膜间,分别于术后2、4周取材,行组织学及免疫组织化学观察血管化情况,并应用图像分析软件计算支架血管化面积。结果支架体外预血管化后,其网管内可见微血管内皮细胞均匀贴壁。支架植入体内2周,切片血管化面积A组为2260.91±242.35μm2与B组823.64±81.29μm2比较,差异有统计学意义(P<0.01);4周时A组为17284.36±72.67μm2与B组17041.14±81.51μm2比较,差异无统计学意义(P>0.05)。植入2周支架切片肌动蛋白阳性染色面积A组为565.22±60.58μm2与B组205.91±16.25μm2比较,差异有统计学意义(P<0.01);4周时A组为4321.09±19.82μm2与B组4260.28±27.17μm2比较,差异无统计学意义(P>0.05)。结论含网管的多孔可降解PLGA支架是一种良好的简易血管化支架模型;预血管化可以明显增强支架植入早期的血管化。     

聚乳酸-羟基乙酸编织网/胶原-壳聚糖真皮替代物的设计及生物学性能初步评价

目的 设计并构建一种含有编织网的连续性真皮再生模板,并初步评价其生物学性能.方法 采用冷冻-冻干法将聚乳酸-羟基乙酸(PLGA)编织网整合到胶原-壳聚糖支架(CCS)中,形成PLGA编织网/胶原-壳聚糖复合支架(PCCS),对比PLGA编织网、PCCS、CCS微观形态及机械强度.将PCCS及CCS分别埋植于18只SD大鼠皮下(PCCS组、CCS组,每组9只大鼠).术后1、2、4周取埋植部位皮肤标本,行组织形态学观察及免疫组织化学观察(用CD68抗体对巨噬细胞染色),蛋白质印迹法检测CD68、髓过氧化物酶(MPO)、IL-1β、IL-10的蛋白含量.对数据行单因素方差分析和t检验.结果 含有编织网的PCCS具有类似CCS的三维多孔结构;PLGA编织网与PCCS的机械强度分别为(3.07±0.10)、(3.26±0.15)MPa,明显优于CCS[(0.42±0.21)MPa,F=592.3,P＜0.0001].PCCS组约在术后2周完成全层组织长入,CCS组于术后4周才实现这一过程.PCCS组、CCS组均出现巨噬细胞聚集的现象,在术后2周达到高峰,且CCS组可见更多数量的巨噬细胞浸润.术后2周,PCCS组IL-10蛋白含量高于CCS组,而CD68、MPO、IL-1β蛋白含量则低于CCS组(t=-4.06～2.89,P＜0.05或P＜0.01).结论 支架的三维结构与机械强度之间的相互作用,在诱导组织再生中非常重要.PCCS连续性真皮再生模板具有优良的机械性能,合适的三维多孔结构和快速诱导组织、细胞及血管长人的潜能,作为真皮替代物具有一定应用前景.

Abstract：

Objective To design and construct a kind of dermal regeneration template with mesh,and to preliminarily evaluate its biological characteristics. Methods PLGA mesh was integrated into CCS with freeze-drying method for constructing PLGA mesh/CCS composite (PCCS). The micromorphologies and mechanical properties among PLGA mesh, CCS, and PCCS were compared. PCCS and CCS was respectively implanted into subcutaneous tissue of SD rats(PCCS and CCS groups, 9 rats in each group). The tissue samples were collected at post operation week (POW) 1, 2, and 4 for histopathological and immunohistochemical observation. Protein levels of CD68, MPO, IL-1 β, IL-10 were examined by Western blot, with expression of gray value. Data were processed with one-way analysis of variance and t test. Results Threedimensional porous structure of PCCS was similar to that of CCS. Mechanical property of PLGA mesh and PCCS was respectively (3.07 ±0. 10), (3.26 ±0. 15) MPa, and they were higher than that of CCS [(0.42 ±0.21) MPa, F = 592.3, P ＜ 0. 0001)]. The scaffolds were filled with newly formed tissue in PCCS group at POW 2, while those in CCS group were observed at POW 4. A large accumulation of macrophages was observed in both groups, especially at POW 2, and more macrophage infiltration was observed in CCS group. The protein level of IL-10 in PCCS group at POW 2 was obviously higher than that in CCS group, while the protein levels of CD68, MPO, IL-1 β were significantly decreased as compared with those in CCSgroup (with t value from -4.06to2.89,P ＜0.05orP ＜0.01). Conclusions PCCS has excellent mechanical property with appropriate three-dimensional porous structure. Meanwhile, it can rapidly induce formation of new tissue and vascularization, and it has a prospect of serving as a dermal substitute.     

单唾液酸四己糖神经节苷脂乳酸/羟基乙酸共聚物微球对大鼠脊髓损伤后神经功能的影响

目的：探讨经蛛网膜下腔注入单唾液酸四己糖神经节苷脂（monosialotetrahexosylgangliosides,GM-1）乳酸/羟基乙酸共聚物（poly lactic-co-glycolic acid,PLGA）微球对大鼠脊髓损伤（spinal cord injury,SCI）后神经功能的影响。方法：94只成年SD大鼠随机分为4组：微球治疗组（A组）、普通GM-1制剂治疗组（B组）和损伤对照组（C组）各30只,正常对照组（D组）4只。A、B、C组大鼠采用Nystrom法制备T10脊髓压迫损伤模型,伤后即刻开始给药,A组大鼠经蛛网膜下腔一次性注入20μlGM-1PLGA微球悬液（含GM-150μg）,B组大鼠伤后至处死前每24h一次经尾静脉注入GM-1普通制剂30mg/kg,C组大鼠经蛛网膜下腔一次性注入20μl生理盐水,D组大鼠不手术、不给药。A、B、C组大鼠于术后1、3、7、14d进行脊髓运动功能（BBB）评分,术后1、7、14d检测运动诱发电位,术后8h、1d、3d、7d、14d检测大鼠脑脊液中GM-1含量;术后8h、1d、3d、7d、14d处死动物（n=6）,取T10节段脊髓并切片,用HE染色观察脊髓组织学变化,用免疫组化染色方法检测SCI后14d时损伤脊髓组织中NF200表达情况。D组上述各指标的检测不分时间点,只进行1次。结果：各时间点A、B、C组大鼠BBB评分均显著低于D组（P〈0.01）,术后3d、7d、14d时A、B组显著高于C组（P〈0.01）,各时间点A组与B组无显著性差异（P〉0.05）。各时间点A、B、C组大鼠运动诱发电位N1波潜伏期较D组明显延长、波幅明显降低（均P〈0.01）,但术后1d和7d时A、B组N1波潜伏期明显较C组短（P〈0.01）,术后7d和14d时A、B组N1波波幅明显较C组高（P〈0.01）,各时间点A组与B组比较无显著性差异（P〉0.05）。各时间点A、B组大鼠脑脊液内GM-1含量均显著高于C组和D组（均P〈0.01）,术后8h、1d、3d时A组明显高于B组（P〈0.01或0.05）,术后7、14d时A组与B组比较无显著性差异,C组和D组比较无显著性差异（P〉0.05）。HE染色,D组正常,术后各时间点A、B组大鼠脊髓损伤区组织形态优于C组,而A组与B组大鼠脊髓损伤区组织形态基本相似。A组、B组和C组大鼠SCI后14d损伤脊髓组织中NF200阳性细胞平均光密度（AOD）值均显著低于D组（P〈0.01）,但A、B组均显著高于C组（P〈0.01）,A组和B组间无显著性差异。结论：经蛛网膜下腔注入GM-1PLGA微球对大鼠脊髓损伤后神经功能具有良好的保护作用,与外周应用普通GM-1制剂比较,能减少药物用量,快速提高局部药物浓度,并较长时间维持稳定,提高生物利用率,且疗效相当。     

Designing a Three-dimensional Expanded Polytetrafluoroethylene–Poly(lactic-co-glycolic acid) Scaffold for Tissue Engineering

Abstract:  The purpose of this study was to design a three-dimensional expanded polytetrafluoroethylene (ePTFE)–poly(lactic-co-glycolic acid) (PLGA) scaffold for tissue engineering. To test the feasibility of this composite scaffold, a series of two-dimensional culture experiments were performed to investigate the behavior of anterior cruciate ligament (ACL) cells on the ePTFE and PLGA membranes. It was found PLGA provided a cell-favorable substrate for cell adhesion, migration, and growth, indicating PLGA is an ACL cell-conductive material. Conversely, poor adhesion and proliferation of ACL cells were observed on the ePTFE, even on the collagen-coated ePTFE. Therefore, the scaffold was not fabricated by coating PLGA on the ePTFE surface because it is difficult to coat anything on the extremely hydrophobic ePTFE surface. Instead, the ePTFE embedded in the PLGA matrix was prepared by immersing ePTFE scrim yarns into the PLGA solution, and then precipitating PLGA to form a three-dimensional construction with porous morphology. The role of ePTFE is regarded as a reinforcing constituent to improve the mechanical strength of porous PLGA matrix to provide early repair strength for tissue healing. However, porous PLGA matrix acts as a supportive environment for allowing cell adhesion, migration, and growth to guide the repair and regeneration of ligament tissue. To test this assumption, a preliminary animal experiment of rabbit ACL wound healing with this three-dimensional ePTFE–PLGA scaffold was performed. These results are very encouraging because such a new scaffold made of ePTFE scrim yarns embedded in PLGA may serve as ACL prostheses in the ligament tissue engineering.     

载利福喷丁/聚乳酸-聚乙醇酸共聚物微球制备及体外释放

目的：制备可用于持续抑制脊柱结核术后病灶残留结核分枝杆菌的载利福喷丁／聚乳酸-聚乙醇酸共聚物[ Poly（ lactic-co-glycolic acid）, PLGA]微球,并研究其体外释放性能。方法通过乳化-溶剂挥发法制备载利福喷丁／PLGA微球,光学显微镜和扫描电镜观察微球形貌,激光粒度分布仪测定微球粒径及分布,紫外分光光度计测定微球载药量及包封率。检测利福喷丁抗结核分枝杆菌的最低抑菌浓度,并以pH＝7．4的PBS缓冲溶液为释放介质,紫外分光光度计检测载药微球体外释放特性。结果载利福喷丁／PLGA微球成球形状良好,表面光滑,分散性好,粒径分布均匀,平均粒径为25．49μm。载药量及包封率分别为21．37％±0．16％和74．79％±2．71％。体外释放实验显示在突释期内,利福喷丁释放量占载药微球中药物含量的37．08％±1．68％;在缓释期内载药微球释药速度减慢,第5周释放量仍超过利福喷丁抗结核分枝杆菌的最低抑菌浓度,35 d后体外累积释放量为80．67％±0．97％,仍高于利福喷丁抗结核分枝杆菌的最低抑菌浓度2μg／mL。结论 PLGA是一种理想的控缓释材料,所制备的载利福喷丁／PLGA微球具有良好的控释效果,是一种有效的抗结核缓释剂型。     

Differentiation pattern of Vero cells cultured on poly(L-lactic acid)/poly(hydroxybutyrate-co-hydroxyvalerate) blends

This study evaluates the effect of poly(L-lactic acid) (PLLA) and poly(hydroxybutyrate-cohydroxyvalerate) (PHBV) bioabsorbable polymers and their blends on the induction of alteration of cell growth pattern in vitro. Vero cells were cultured on PLLA, PHBV, and different blends (100/0, 60/40, 50/50, 40/60, and 0/100). The cell adhesion assay showed that the best results were obtained with the (60/40, 50/50) blends. Scanning electron microscopy showed that the cells on (100/0) and (60/40) samples grew with a round morphology preferentially in the porous areas. The (50/50) blends had cells in the porous and smooth areas in a similar way. The (40/60) blends showed spreading cells on the smooth areas. The (0/100) sample, which had no pores, had spreading cells interconnected by filaments. Histological sections showed a confluent cell monolayer and the immunocytochemistry showed that the cells produced collagen IV and fibronectin on all substrates. Thus, we conclude that PLLA/PHBV blends were efficient in maintaining cell growth and producing an extracellular matrix on them.     

Sciatic nerve repair with tissue engineered nerve: Olfactory ensheathing cells seeded poly(lactic-co-glygolic acid) conduit in an animal model

Background and Aim:

Synthetic nerve conduits have been sought for repair of nerve defects as the autologous nerve grafts causes donor site morbidity and possess other drawbacks. Many strategies have been investigated to improve nerve regeneration through synthetic nerve guided conduits. Olfactory ensheathing cells (OECs) that share both Schwann cell and astrocytic characteristics have been shown to promote axonal regeneration after transplantation. The present study was driven by the hypothesis that tissue-engineered poly(lactic-co-glycolic acid) (PLGA) seeded with OECs would improve peripheral nerve regeneration in a long sciatic nerve defect.

Materials and Methods:

Sciatic nerve gap of 15 mm was created in six adult female Sprague-Dawley rats and implanted with PLGA seeded with OECs. The nerve regeneration was assessed electrophysiologically at 2, 4 and 6 weeks following implantation. Histopathological examination, scanning electron microscopic (SEM) examination and immunohistochemical analysis were performed at the end of the study.

Results:

Nerve conduction studies revealed a significant improvement of nerve conduction velocities whereby the mean nerve conduction velocity increases from 4.2 ΁ 0.4 m/s at week 2 to 27.3 ΁ 5.7 m/s at week 6 post-implantation (P < 0.0001). Histological analysis revealed presence of spindle-shaped cells. Immunohistochemical analysis further demonstrated the expression of S100 protein in both cell nucleus and the cytoplasm in these cells, hence confirming their Schwann-cell-like property. Under SEM, these cells were found to be actively secreting extracellular matrix.

Conclusion:

Tissue-engineered PLGA conduit seeded with OECs provided a permissive environment to facilitate nerve regeneration in a small animal model.     

bFGF-PLGA微球促进随意皮瓣早期断蒂

目的 :探讨碱性成纤维细胞生长因子 -聚乳酸 /聚乙醇酸 (bFGF PLGA)微球促进随意皮瓣早期断蒂。方法 :通过复乳溶剂挥发法制备bFGF PLGA微球 ,采用60 Co辐照灭菌。将bFGF PLGA微球注入大鼠背部随意皮瓣下方 ,4d后断蒂 ,断蒂后 10d观察皮瓣成活率、新生微血管数量。并与单独使用bFGF组进行对比。结果 :皮瓣成活率A组为 (89 2± 2 6 0 ) %,B组为 (85 6± 2 9 7) %,C组为 (76 6± 3 2 2 ) %。新生血管数A组为 2 9 7,B组为 2 4 6,C组为 12。经统计学分析 ,各组间存在显著差异。结论 :bFGF PLGA微球能够更好地促进随意皮瓣的早期断蒂。     

Long-lasting bioresorbable poly(lactic acid) (PLA<Subscript>94</Subscript>) mesh: a new approach for soft tissue reinforcement based on an experimental pilot study

The purpose of this study was to evaluate host response and soft-tissue regeneration after poly(lactic acid) (PLA) mesh implantation in a rat model, in comparison with light-weight polypropylene (PPL) and poly(glycolic acid) (PGA) meshes. Full-thickeness abdominal wall defects were created in 45 Wistar rats and reconstructed with 15 PLA₉₄, 15 PPL and 15 PGA meshes. Animals were killed on days 7, 30 and 90 to evaluate the presence of adhesions and changes in tensile strength of the implants. Histolopathology and immunohistochemistry were performed to evaluate the collagen deposition and the inflammatory response. Statistics were done using unpaired Student’s t-test, Mann–Whitney rank sum test, Student–Newman–Keuls test and Bonferroni (Dunn) t-test. The inflammatory response induced by the PLA mesh implantation was significantly milder than after PPL mesh. In PLA, vascularity and collagen organization was significantly higher than in PPL and PGA at 30 and 90 days, and collagen composition score was significantly higher than in PPL at 7 and 30 days. In PLA, shrinkage was significantly lower than in PPL and PGA at 7 and 30 days. Elongation at break and tensile strength were comparable between PLA and PPL over the 90-day period. The PLA mesh induces a milder inflammatory response, more orderly collagen deposition than PPL, and preserved comparable tensile strength after 90 days.     

局部用雷帕霉素聚乳酸乙醇酸共聚物缓释微球的制备及释药研究

目的：介绍雷帕霉素（RAPA）聚乳酸乙醇酸共聚物（PLGA）缓释微球的制备方法,建立高效液相色谱法（HPLC）测定体系以检测微球中雷帕霉素含量,检测微球性状并进行体外释药实验。方法：以聚乳酸乙醇酸共聚物为载体,采用W/O/W乳剂-扩散溶剂挥发法制备雷帕霉素缓释微球,扫描电镜检测微球外观及微球粒径,HPLC检测微球载药量、包封率及体外释药量。结果：所制微球光滑圆整,大小均一,平均粒径：（121.18±27.83）μm,载药率：（14.39±1.32）%,包封率：（72.92±4.29）%,体外释放实验显示1～4天有突释,随后平稳释药至第10天累积释药率达80%。结论：采用制备工艺稳定,所制微球载药量及包封率均较高,形态完整,大小均一,体外释药较为平稳并且具有明显的缓释作用。     

Vero cell growth and differentiation on poly(L-lactic acid) membranes of different pore diameters

In the last few years, the demand has increased for research on polymeric materials, which can be used as substitutes for injured tissues and organs or to improve their regeneration. In this work, we studied poly(L-lactic acid) (PLLA) membranes, a resorbable biomaterial, which were either dense or had different pore diameters (less than 45 microm, between 180 and 250 microm, and between 250 and 350 microm), in relation to stimulation of cell adhesion, growth, and differentiation in vitro. We used Vero cells, a fibroblastic cell line, as the biological model of investigation. We found that cells attached slowly to all PLLA membranes studied. On the other hand, once the adhesion occurs, the cells are able to grow and differentiate on the different polymers. The cells grew to form a confluent monolayer and were capable of producing collagen Type IV and fibronectin on different PLLA membranes. This behavior indicates that cells try to create a better environment to stimulate their growth. This also indicates that Vero cells alter their differentiation pattern once they are producing extracellular matrix molecules related to epithelial differentiation.     

Effect of epidural clonidine on minimum local anesthetic concentration (ED50) of levobupivacaine for caudal block in children

Background: Clonidine has the potential to significantly prolong the duration of caudal epidural anesthesia. We investigated the effect of the addition of clonidine to the MLAC of levobupivacaine in a randomized controlled dose–response trial. Methods: A group of 120 children aged <6 years of age received caudal anesthesia with levobupivacaine and 1, 2, or 3 μg·kg^?1 of clonidine. The MLAC was determined according to a Dixon‐Massey protocol. The primary outcome was effective surgical anesthesia. Secondary outcomes were the duration of postoperative analgesia, postoperative pain scores, clonidine side effects, and time to hospital discharge. Results: The MLAC of caudal levobupivacaine was 0.106%, 0.077%, and 0.035% with 1, 2, and 3 μg·kg^?1 of clonidine, respectively. There were significant dose‐dependent increases in median duration of analgesia. The incidence of delayed discharge, somnolence, and PONV was significantly increased in the 3 μg·kg^?1 of clonidine group. Conclusions: Clonidine produces a local anesthetic sparing effect with a dose‐dependent decrease in levobupivacaine MLAC for caudal anesthesia. In addition, there is a dose‐dependent prolongation of postoperative analgesia following lower abdominal surgery in children. A dose of 2 μg·kg^?1 of clonidine provides the optimum balance between improved analgesia and minimal side effects.