两种组织工程化人工肋骨支架材料的制备及体内外降解实验研究

目的选择组织工程界常用的聚乳酸-羟基乙酸共聚物／羟基磷灰石（PLGA／HA）与多孔磷酸钙（CPC）两种支架材料,通过体内外降解实验筛选出更为符合组织工程化人工肋骨支架的材料。方法将PLGA／HA（PLGA／HA组）和CPC（CPC组）两种材料分别进行体外实验和动物体内实验,体外实验：将同等大小的PLGA／HA和CPC材料浸入0．9％NaCl溶液,并保持无菌,放入37℃温箱内,分别于2、4、8、12和24周时取出称重,比较两种材料在体外的降解速度差异;体内实验：将同等大小的PLGA／HA和CPC材料各2片分别植入20只新西兰大白兔脊柱两侧的皮下,于2、4、8、12和24周取出称重,各时间点分别处死4只大白兔;材料周围组织送组织学检查及扫描电子显微镜观察。结果薄层CT扫描（Micro—CT）和扫描电子显微镜观察结果,CPC组较PLGA／HA组具有较好的三维结构（1101．2228±0．6184mg／ccm vs．1072．5523±0．7442mg／ccm）及孔隙率（70．26％±0．45％ vs．72．82％±0．51％）;体外实验显示：两组材料在体外降解速度均较慢,至6个月时才有明显的降解,其中PLGA／HA组降解相对较多,降解了60％;体内实验显示：PLGA／HA组降解比体外更快,3个月时已基本降解完,比CPC组降解快,降解了96％;另外CPC组材料周围的炎症反应明显比PLGA／HA组轻,更适合细胞的生长和黏附。结论对再生时间较长的长段肋骨缺损,CPC比PLGA／HA更适合。     

Enhancing the therapeutic efficacy of CpG oligonucleotides using biodegradable microparticles

Oligonucleotides, with specific sequence surrounding CpG motifs, appear to be very effective for the induction of a potent Th1 responses. This molecule represents pathogen-associated molecular patterns (PAMPs) that allows the pathogen recognition receptors (PRRs) present on innate immune cells to recognize them and become activated. PAMPs and related compounds are often labelled as immunopotentiators, allowing a clear distinction between them and particulate delivery systems such as emulsions, liposomes, virus-like particles and microparticles.Microparticles prepared from biodegradable, biocompatible polyesters, and poly (lactide co-glycolide) (PLG). They have been proven to be a good particulate delivery system for the co-delivery of antigens and adjuvants. PLG has been used in humans for many years as a resorbable suture material and controlled-release drug delivery systems. It has been demonstrated that antigen presenting cells (APCs) efficiently uptake the PLG microparticles (∼ 1 μm) both in vivo and in vitro. After uptake, the PLG subsequently induces an antigen specific CTL response in rodents.Several groups, including our group, have evaluated CpG as an immunopotentiator in various formulations and delivery systems (i.e. emulsions and particulate systems). This review will discuss in detail the work conducted so far with CpG using PLG microparticles as a delivery system. We will also discuss the advantages and enhancement of immune properties of formulating CpG (soluble, adsorbed, and encapsulated forms) with PLG microparticles along with future directions for these microparticles with CpG.     

An in vitro study of the design and development of a novel doughnut-shaped minitablet for intraocular implantation

A novel doughnut-shaped minitablet (DSMT) was developed and evaluated as a biodegradable intraocular drug delivery system for rate-modulated delivery of antiviral bioactives. The DSMT device was manufactured using a special set of punches fitted with a central-rod in a Manesty tableting press. The DSMT device released the antiretrovirals foscarnet and ganciclovir at a first-order rate. The erosion kinetics was assessed by gravimetric analysis and scanning electron microscopy. The device gradually eroded when immersed in simulated vitreous humor (SVH) (pH 7.4, 37 °C) and released bioactives in a sustained manner. The novel geometric design and veracity of the DSMT device was retained even after 24 weeks of erosion. When considering the duration of the bioactive released from the DSMT device, it was found that by the careful selection of the type and concentration of polymer employed in formulating the DSMT device, it was possible to produce a device that could release drug for any period up to 12 months.     

A guide to oral vaccination: Highlighting electrospraying as a promising manufacturing technique toward a successful oral vaccine development

Most vaccines approved by regulatory bodies are administered via intramuscular or subcutaneous injections and have shortcomings, such as the risk of needle-associated blood infections, pain and swelling at the injection site. Orally administered vaccines are of interest, as they elicit both systemic and mucosal immunities, in which mucosal immunity would neutralize the mucosa invading pathogen before the onset of an infection. Hence, oral vaccination can eliminate the injection associated adverse effects and enhance the person's compliance. Conventional approaches to manufacturing oral vaccines, such as coacervation, spray drying, and membrane emulsification, tend to alter the structural proteins in vaccines that result from high temperature, organic and toxic solvents during production. Electrohydrodynamic processes, specifically electrospraying, could solve these challenges, as it also modulates antigen release and has a high loading efficiency. This review will highlight the mucosal immunity and biological basis of the gastrointestinal immune system, different oral vaccine delivery approaches, and the application of electrospraying in vaccines development.     

不同制备工艺对胶质细胞源性神经营养因子微球理化性质及生物活性的影响

目的 评价不同制备工艺对胶质细胞源性神经营养因子(glial cell line-derived neurotrophic factor,GDNF)缓释微球的影响及微球所包裹的GDNF生物学活性.方法 以聚乳酸-羟基乙酸共聚物(polylactide-co-glycolide,PLGA)为包裹材料,采用复乳法(W1/O/W2)制备GDNF-PLGA微球,通过两因素析因设计方差分析,研究PLGA中乳酸(LA)与羟基乙酸(GA)单体组成比例和复乳搅拌速度对GDNF微球的粒径、包封率、突释率和体外释放行为的影响,并用PC-12细胞检测微球所释放的GDNF生物学活性,确定最佳制备工艺.结果 PLGA的单体组成比例可影响微球的突释率(P＜0.05),对粒径和包封率的影响无统计学意义,随着GA比例的增加,微球中GDNF释放速度加快.复乳搅拌速度由1 000 r/min增加到3 000 r/min后,微球的粒径显著减小(P＜0.01),突释率显著增加(P＜0.01),体外释放更为快速.微球中的GDNF在37℃下活性有效期可达20 d左右,较单独存放的GDNF活性有效期延长10 d以上.结论 复乳法可制备具有较高包封率和适宜体外释放时间的GDNF缓释微球,且活性有效期延长.

Abstract：

Objective To evaluate the effect of different preparation processes on preparation of the glial cell line-derived neurotrophic factor(GDNF)loaded microspheres and observe the biological activity of GDNF.Methods With polylactide-co-glycolide(PLGA)as the coating material,the GDNF-loaded microspheres were prepared by using double emulsion(W1/O/W2).Two-factor factorial design variance analysis was done to analyze the effects of the composition proportion of lactic acid(LA)and glycolic acid(GA)in PLGA and the stirring speed of multiple emulsion on particle size,entrapment efficiency,burst release and in vitro release characteristics of the GDNF-loaded microspheres.PC-12 bioassay was employed to detect the biological activity of the released GDNF so as to determine the optimal preparation process.Results The composition proportion of PLGA could affect the microspheres'burst release(P ＜ 0.05),with no effect on particle size and entrapment efficiency.with the higher.With higher proportion of GA,the release speed of GDNF in the microspheres was increased.When the stirring speed of multiple emulsion was increased from 1 000 r/min to 3 000 r/min,the particle size of the microspheres was decrease significantly(P ＜ 0.01),the burst release was increased markedly(P ＜ 0.01)and the in vitro release rate was accelerated.The activity of GDNF in the microspheres could last for about 20 days at 37℃,which was 10 days longer than that of single GDNF.Conclusions Double emulsioncan prepare the GDNF-loaded microspheres with high entrapment efficiency and suitable in vitro release time.In the meantime,the microspheres can extend the validity of GDNF.