电纺参数对PLGA/HA复合支架纤维形貌和直径的影响

目的通过静电纺丝的方法制备PLGA/HA复合支架,探讨电纺参数对复合支架纤维形貌和直径的影响。方法以三氯甲烷和N,N-二甲基甲酰胺为混合溶剂制备PLGA/HA纺丝液,通过调节PLGA的浓度、电压、接收距离,制备具有不同表面形貌的PLGA/HA复合纤维,采用SEM观察PLGA的浓度、电压、接收距离对纤维形貌和直径的影响。结果复合纤维的直径随PLGA浓度的增加而增加;随电压的增加而增加;随接收距离的增加先减小后增加。结论制备PLGA/HA复合支架较合适的电纺参数为：PLGA浓度25%,电压20KV,接收距离15cm。静电纺丝法制得的PLGA/HA复合支架有可能作为骨组织再生的支架在组织工程领域发挥作用。     

PLGA-modified Syloid®-based microparticles for the ocular delivery of terconazole: in-vitro and in-vivo investigations

The eye is an invulnerable organ with intrinsic anatomical and physiological barriers, hindering the development of a pioneer ocular formulation. The aim of this work was to develop an efficient ocular delivery system that can augment the ocular bioavailability of the antifungal drug, terconazole. Mesoporous silica microparticles, Syloid^® 244 FP were utilized as the carrier system for terconazole. Preliminary studies were carried out using different drug:Syloid^® weight ratios. The optimum weight ratio was mixed with various concentrations (30 and 60%w/w) of poly (lactic-co-glycolic acid) (PLGA), ester or acid-capped and with different monomers-ratio (50:50 and 75:25) using the nano-spray dryer. Results revealed the superiority of drug:Syloid^® weight ratio of 1:2 in terms of yield percentage (Y%), SPAN and drug content percentage (DC%). Furthermore, incorporation of PLGA with lower glycolic acid monomer-ratio significantly increased Y%. In contrast, increasing the glycolic acid monomer-ratio resulted in higher DC% and release efficiency percentage (RE%). Additionally, doubling PLGA concentration significantly reduced Y%, DC%, drug loading percentage (DL%) and RE%. Applying desirability function in terms of increasing DC%, DL% besides RE% and decreasing SPAN, the selected formulation was chosen for DSC, XRD and SEM investigations. Results confirmed the successful loading of amorphized terconazole on PLGA-modified Syloid^® microparticles. Moreover, pharmacokinetic studies for the chosen formulation on male Albino rabbits’ eyes revealed a 2, 6.7 and 25.3-fold increase in mean residence time, C_max and AUC_0–24-values, respectively, compared to the drug suspension. PLGA-modified Syloid^® microparticles represent a potential option to augment the bioavailability of ocular drugs.     

Cell membrane-camouflaged PLGA biomimetic system for diverse biomedical application

The emerging cell membrane (CM)-camouflaged poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs) (CM@PLGA NPs) have witnessed tremendous developments since coming to the limelight. Donning a novel membrane coat on traditional PLGA carriers enables combining the strengths of PLGA with cell-like behavior, including inherently interacting with the surrounding environment. Thereby, the in vivo defects of PLGA (such as drug leakage and poor specific distribution) can be overcome, its therapeutic potential can be amplified, and additional novel functions beyond drug delivery can be conferred. To elucidate the development and promote the clinical transformation of CM@PLGA NPs, the commonly used anucleate and eukaryotic CMs have been described first. Then, CM engineering strategies, such as genetic and nongenetic engineering methods and hybrid membrane technology, have been discussed. The reviewed CM engineering technologies are expected to enrich the functions of CM@PLGA for diverse therapeutic purposes. Third, this article highlights the therapeutic and diagnostic applications and action mechanisms of PLGA biomimetic systems for cancer, cardiovascular diseases, virus infection, and eye diseases. Finally, future expectations and challenges are spotlighted in the concept of translational medicine.     

Icaritin-loaded PLGA nanoparticles activate immunogenic cell death and facilitate tumor recruitment in mice with gastric cancer

This study aimed to explore the anti-tumor effect of icaritin loading poly (lactic-co-glycolic acid) nanoparticles (refer to PLGA@Icaritin NPs) on gastric cancer (GC) cells. Transmission Electron Microscope (TEM), size distribution, zeta potential, drug-loading capability, and other physicochemical characteristics of PLGA@Icaritin NPs were carried out. Furthermore, flow cytometry, confocal laser scanning microscope (CLSM), Cell Counting Kit-8 (CCK-8), Transwell, Elisa assay and Balb/c mice were applied to explore the cellular uptake, anti-proliferation, anti-metastasis, immune response activation effects, and related anti-tumor mechanism of PLGA@Icaritin NPs in vitro and in vivo. PLGA@Icaritin NPs showed spherical shape, with appropriate particle sizes and well drug loading and releasing capacities. Flow cytometry and CLSM results indicated that PLGA@Icaritin could efficiently enter into GC cells. CCK-8 proved that PLGA@Icaritin NPs dramatically suppressed cell growth, induced Lactic dehydrogenase (LDH) leakage, arrested more GC cells at G2 phase, and inhibited the invasion and metastasis of GC cells, compared to free icaritin. In addition, PLGA@Icaritin could help generate dozens of reactive oxygen species (ROS) within GC cells, following by significant mitochondrial membrane potentials (MMPs) loss and excessive production of oxidative-mitochondrial DNA (Ox-mitoDNA). Since that, Ox-mitoDNA further activated the releasing of damage associated molecular pattern molecules (DAMPs), and finally led to immunogenic cell death (ICD). Our in vivo data also elaborated that PLGA@Icaritin exerted a powerful inhibitory effect (∼80%), compared to free icaritin (∼60%). Most importantly, our results demonstrated that PLGA@Icaritin could activate the anti-tumor immunity via recruitment of infiltrating CD4+ cells, CD8+ T cells and increased secretion of cytokine immune factors, including interferon-γ (IFN-γ) tumor necrosis factor-α (TNF-α) and interleukin-1 (IL-1).⁺⁺ Our findings validate that the successful design of PLGA@Icaritin, which can effectively active ICD and facilitate tumor recruitment in GC through inducing mitoDNA oxidative damage.     

常用的蛋白质保护剂对NGF-PLGA微球性质的影响

目的研究常用的蛋白质保护剂对微球性质的影响特点。方法复乳化溶剂挥发法制备NGF-PLGA微球,分别添加葡萄糖,聚乙二醇,卵清蛋白作保护剂,观察微球的形态,载药量、包封率及体外释放特点,研究保护剂的作用特点。结果保护剂对微球的粒径、包封率和载药量影响不明显,粒径集中分布在10-40μm,载药量0．0007％-0．0011％,包封率7％～11％。保护剂主要影响微球的形态和体外释放。添加不同的保护剂,微球表面的光滑度和孔隙差别较大;体外释放的突释较小,存在明显的缓慢释放期,进入快速释放期的起始时间和释药速度受保护剂影响显著,一个月内的累积释放药量达到80％以上。结论保护剂的分子量可能是微球形态和释放不同的原因,添加分子量大的保护剂形成的微球的表面比添加分子量小的保护剂时致密光滑,体外的缓慢释放期长。     

外科植入引导牙周组织再生载药PLGA/CS/nHA复合膜的制备及表征

目的 制备聚乳酸-羟基乙酸共聚物(PLGA)/壳聚糖(CS)/纳米羟基磷灰石(nHA)多孔性载药膜,用于外科植入牙周引导组织再生,并评价其体外性能.方法 按照PLGA/CS的质量比将实验设为4组:分别为100/0、90/10、80/20、70/30,采用冷冻干燥法制备PLGA/CS/nHA复合膜,并用聚乙烯吡咯烷酮(PVP)作为致孔剂.依据孔隙率、吸水率、力学性能、体外降解率筛选出最优质量比的PLGA/CS/nHA复合膜作为药物载体,制备克林霉素缓释膜.采用扫描电子显微镜观察PLGA/CS/nHA复合膜的表面形貌,无水乙醇液体置换法检测复合膜的孔隙率,质量干湿率比考察复合膜的吸水率,电子万能材料实验机测试复合膜的湿态力学性能,质量损失考察膜的降解率,紫外分光光度法考察载药膜的体外药物释放特性.体外实验:在载药膜上接种牙周膜成纤维细胞(PLFs),培养1～7 d,采用CCK-8法测定细胞活性和增殖情况.结果 PLGA/CS质量比为90∶10时制备的PLGA/CS/nHA复合膜最为理想,孔隙率为(28.66±1.35)％,吸水率为(108.65±2.27)％,拉伸强度为(2.36±0.04) MPa,断裂伸长率为(203.64±3.89)％,断裂力为(45.98±2.46)N,30 d时降解率为(17.60±0.86)％,最大每日释放量为150 μg/mL,平稳释放药物并维持有效药物浓度时间＞15 d,载药膜能促进牙周膜成纤维细胞的增殖.结论 本研究制备的载药PLGA/CS/nHA复合膜孔隙率适中,体外降解与组织生长相适应,力学测试结果能够创造和维持牙周引导组织生长特定的空间,在一定时间内能持续稳定释放药物.     

以冻干骨为平台重建组织工程化关节软骨的研究

目的:探索在兔冻干异体骨关节平台上利用组织工程的方法再造人工关节软骨的可行性。方法:实验分成四组,运用组织工程方法将不同构成的同种异体兔软骨细胞-支架材料复合物种植于兔冻干异体骨关节平台上,植入实验兔体内,3月后取材观察体内成软骨情况。结果:仅种植兔软骨细胞的冻干骨关节支架上未见新生软骨形成。粘合有种植兔软骨细胞的PLGA膜片的冻干骨支架关节腔内见新生类软骨样物出现。自体软骨层孔洞缺损模型使用软骨细胞-PLGA膜片复合物可修复软骨缺损。结论:软骨细胞-PLGA膜片复合物实验动物关节内可形成软骨样物;但在冻干骨关节平台上尚不能形成有功能意义的关节软骨层。     

椎体间纤维性融合重建兔脊柱稳定性的初步探索

目的:研究椎体间纤维性融合后脊柱节段的稳定性,探讨椎体间纤维性融合在治疗脊柱节段失稳中的可行性。方法:将18只6月龄新西兰白兔随机分为两组,均摘除L4/5椎间盘髓核,A组在椎间植入环状聚乳酸-聚羟基乙酸(poly L-lactic-co-glycolic-acid,PLGA)可吸收支架;B组单纯髓核摘除。于术前、术后4周、12周行X线检查,运用Image J软件测量椎间盘高度指数(DHI)并计算其百分数(%DHI),分别于术后4周、8周、12周处死3只动物,行组织病理及免疫组化观察。结果:1只动物死亡,17只实验动物术后存活至预期时间,未补充实验动物。12周时,侧位X线片示两组椎间高度较术前均有下降,两组椎间高度的差异有统计学意义(P<0.05),A、B两组屈伸活动度与术前相比差异均无统计学意义(P>0.05)。X线片显示A组手术节段椎体无明显移位及反向成角,B组1只兔子出现前屈位腰椎后凸曲度增加,手术节段椎间隙变窄并邻近软骨终板钙化。细胞组织学观察:术后4周时A组见新生血管及纤维组织生成,有少量类软骨细胞出现,未观察到PLGA支架结构;B组见较多纤维细胞生成。术后8周时,A组出现软骨细胞,纤维组织排列不规则,并见少量的胶原纤维及成纤维细胞;B组纤维组织进一步增生,形成瘢痕样组织。术后12周时,A组大量的胶原纤维、软骨组织交互长入,排列杂乱无序,此时的胶原纤维较8周时增多;B组仍为纤维细胞和瘢痕组织,且Ⅰ型胶原表达高于Ⅱ型胶原。结论:椎体间植入PLGA并利用其与椎体骨髓血的诱导成骨作用短期内可以形成椎间纤维融合;短期内观察椎间纤维融合能够维持一定的脊柱节段稳定性并保留部分生理活动功能,但中远期效果有待进一步观察。     

PLGA–PTMC–Cultured Bone Mesenchymal Stem Cell Scaffold Enhances Cartilage Regeneration in Tissue‐Engineered Tracheal Transplantation

The treatment of long‐segment tracheal defect requires the transplantation of effective tracheal substitute, and the tissue‐engineered trachea (TET) has been proposed as an ideal tracheal substitute. The major cause of the failure of segmental tracheal defect reconstruction by TET is airway collapse caused by the chondromalacia of TET cartilage. The key to maintain the TET structure is the regeneration of chondrocytes in cartilage, which can secrete plenty of cartilage matrices. To address the problem of the chondromalacia of TET cartilage, this study proposed an improved strategy. We designed a new cell sheet scaffold using the poly(lactic‐co‐glycolic acid) (PLGA) and poly(trimethylene carbonate) (PTMC) to make a porous membrane for seeding cells, and used the PLGA–PTMC cell‐scaffold to pack the decellularized allogeneic trachea to construct a new type of TET. The TET was then implanted in the subcutaneous tissue for vascularization for 2 weeks. Orthotopic transplantation was then performed after implantation. The efficiency of the TET we designed was analyzed by histological examination and biomechanical analyses 4 weeks after surgery. Four weeks after surgery, both the number of chondrocytes and the amount of cartilage matrix were significantly higher than those contained in the traditional stem‐cell–based TET. Besides, the coefficient of stiffness of TET was significantly larger than the traditional TET. This study provided a promising approach for the long‐term functional reconstruction of long‐segment tracheal defect, and the TET we designed had potential application prospects in the field of TET reconstruction.     

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。