嗅鞘细胞微环境和水凝胶生物支架对脂肪干细胞成嗅鞘样细胞分化的影响

目的 比较研究脂肪干细胞和嗅鞘细胞以两种不同方式共培养后脂肪干细胞P75的阳性表达.方法 以Transwell小室为共培养载体.无支架共培养组以脂肪干细胞接种于上室,嗅鞘细胞接种于下室,支架共培养组以脂肪干细胞联合水凝胶生物支架(BDTM PuraMatrixTM Peptide Hydrogel)接种于上室,嗅鞘细胞接种于下室.检测两组细胞共培养12 d后其脂肪干细胞P75的表达.结果 共培养12 d后无支架共培养组和支架共培养组都有部分细胞表达P75,且支架共培养组表达率更高.结论 脂肪干细胞在嗅鞘细胞生长微环境中能向嗅鞘样细胞分化.     

微波等离子体引发合成P(AMPS/NIPA)新型智能凝胶及其性能

以2-丙烯酰胺-2-甲基丙磺@（AMPS）和异丙基丙烯酰胺（NIPA）为单体，通过微波等离子体引发聚合制备了新型二元智能凝胶P（AMPS／NIPA），并对其性能进行了研究。探讨了等离子体功率及处理时间对聚合反应的影响；研究了该凝胶的温度敏感性、吸水／失水动力学和pH敏感性及其影响因素；对凝胶的组成及三维交联网络结构进行了表征。结果表明，P（AMPS／NIPA）二元智能凝胶具有高的溶胀比、很好的温度敏感性和pH敏感性以及快的智能响应速率。     

聚丙烯酰胺水凝胶注射隆乳术并发症的防治

目的：探讨聚丙烯酰胺水凝胶注射隆乳后并发症的预防和治疗。方法：对收治聚丙烯酰胺水凝胶注射隆乳出现并发症的43例临床资料进行分析总结。结果：43例患者中,硬结9例、血肿6例、感染9例、注射孔形成窦道3例、两侧不对称8例、材料渗至乳房形态以外2例、疼痛5例、较硬包块1例。经正确的处理后大多数患者对治疗结果满意。结论：出现聚丙烯酰胺水凝胶注射隆乳并发症主要原因是操作不规范引起。     

利用海藻酸水凝胶构建仿肝板肝组织三维共培养模型

目的 利用海藻酸水凝胶构建一种新的肝细胞三维共培养模型.方法 利用海藻酸钠、微流控芯片,以及肝细胞C3A和脐静脉内皮细胞EA.hy926制备出海藻酸钠水凝胶微纤维,实验组为仿肝板组,同时制备出混合无序水凝胶微纤维作为对照组.利用活细胞双荧光标记验证微纤维内两种细胞排列结构,将微纤维培养1周,每天观察微纤维形态,检测肝细胞活力及清蛋白(Alb)、丙氨酸氨基转移酶(ALT)、天冬氨酸氨基转移酶(AST)、乳酸脱氢酶(LDH-L)、α1抗胰蛋白酶(α1AT)、凝血因子Ⅶ(FⅦ)、谷胱甘肽S转移酶α1 (GSTα1)、细胞色素P450氧化酶1A2 (CYP1A2)的水平.结果 仿肝板组水凝胶内C3A细胞在中间,有2～3排,EA.hy926细胞位于C3A细胞两侧,呈现肝板结构排布;对照组水凝胶内两种细胞则混杂在一起呈无序状态;大约3d肝组织条索形成;两组水凝胶微纤维直径随时间变化差异无统计学意义(P＞0.05);仿肝板组肝细胞活力在第5天达到最大值,对照组在第6天达到最大值,两组除第1天较接近外,其余各天仿肝板组均高于对照组;两组清蛋白分泌水平变化趋势基本相同,在第3天达到最大值,第4天开始下降;仿肝板组ALT、AST、LDH-L在第3天下降到最小值,第4天以后变化趋势和对照组相同;两组α1AT除第5天外其余各时间点比较差异均有统计学意义(P＜0.05);两组GSTM分泌量随时间持续上升,仿肝板组各时间点明显高于对照组(P＜0.05);仿肝板组FⅦ分泌量前7d逐渐升高,对照组于第2天持续下降,仿肝板组第3天开始明显高于对照组(P＜0.05);对照组细胞内CYP1A2水平随时间变化不明显,仿肝板组从第4天开始明显高于对照组(P＜0.05).结论 成功构建出一种仿肝板肝组织三维共培养模型,肝细胞功能有望得到长时间维持.     

小分子水凝胶对大鼠骨髓间充质干细胞心肌分化过程中早期分化基因表达的影响

目的：探讨小分子水凝胶对大鼠骨髓间充质干细胞（MSCs）心肌分化过程中早期分化基因Desmin和α-actin的表达影响。方法：流式细胞仪检测鉴定P9MSCs细胞表面标记物,分别应用10μmol／L5-aza（5．aza组）、小分子水凝胶＋5-aza（水凝胶组）对第9代MSCs进行联合诱导24h,诱导4周后,QRT-PCR和Western—blotting法检测Desmin、α—actinmRNA及蛋白的表达。结果：第9代MSCsCD44阳性表达、CD34阴性表达;诱导4周后,5-aza组细胞难以形成球状细胞团,细胞容易脱落,凋亡及死亡细胞较多;水凝胶组细胞死亡少,数量较诱导前增多。细胞之间的分支连接紧密,有聚集生长的趋势,形成球状细胞团块,个别细胞内形成类肌管状结构。5-aza组和水凝胶组心肌早期分化基因Desmin、α-actin均有阳性表达．水凝胶组mRNA及蛋白表达水平均较5-aza组明显增强（P〈0．05）。结论：小分子水凝胶可作为细胞的三维培养支架．有利于MSCs生长,具有促进5-aza诱导的MSCs向心肌样细胞分化的作用。     

Hydrogels for oral delivery of therapeutic proteins

In recent years there has been significant new interest in the development of transmucosal (mostly oral) pharmaceutical formulations for the delivery of therapeutic proteins. Emphasis has been given to the molecular design of new carriers for the delivery of insulin, calcitonin and various types of interferons for the treatment of diabetes, osteoporosis, multiple sclerosis and cancer. Most popular carriers include advanced designs of swollen hydrogels prepared from neutral or intelligent polymeric networks. In this review, the most successful of such systems are presented and their promise in the field described.     

A minimally disruptive method for measuring water potential in planta using hydrogel nanoreporters

Leaf water potential is a critical indicator of plant water status, integrating soil moisture status, plant physiology, and environmental conditions. There are few tools for measuring plant water status (water potential) in situ, presenting a critical barrier for developing appropriate phenotyping (measurement) methods for crop development and modeling efforts aimed at understanding water transport in plants. Here, we present the development of an in situ, minimally disruptive hydrogel nanoreporter (AquaDust) for measuring leaf water potential. The gel matrix responds to changes in water potential in its local environment by swelling; the distance between covalently linked dyes changes with the reconfiguration of the polymer, leading to changes in the emission spectrum via Förster Resonance Energy Transfer (FRET). Upon infiltration into leaves, the nanoparticles localize within the apoplastic space in the mesophyll; they do not enter the cytoplasm or the xylem. We characterize the physical basis for AquaDust’s response and demonstrate its function in intact maize (Zea mays L.) leaves as a reporter of leaf water potential. We use AquaDust to measure gradients of water potential along intact, actively transpiring leaves as a function of water status; the localized nature of the reporters allows us to define a hydraulic model that distinguishes resistances inside and outside the xylem. We also present field measurements with AquaDust through a full diurnal cycle to confirm the robustness of the technique and of our model. We conclude that AquaDust offers potential opportunities for high-throughput field measurements and spatially resolved studies of water relations within plant tissues.

Plant life depends on water availability. In managing this demand, irrigated agriculture accounts for 70% of all human water use (1). Physiologically, the process of transpiration (E) dominates this demand for water (Fig. 1A): Solar thermal radiation and the unsaturated relative humidity in the atmosphere drive evaporation from the wet internal surfaces of leaves; this water loss pulls water up through the plant’s vascular tissue (xylem) and out of the soil. This flow occurs along a gradient in the chemical potential of water, or water potential, ψ [MPa] (2). Studies of water relations and stress physiology over the past decades have found that values of ψ along the path of E (the soil–plant–atmosphere continuum [SPAC]) correlate with plant growth, crop yield and quality, susceptibility to disease, and the balance between water loss due to E and the uptake and assimilation of carbon dioxide (water-use efficiency) (3–5).Open in a separate windowFig. 1.AquaDust as an in situ reporter of water potential (ψ). (A) Schematic representation of a maize plant undergoing transpiration (E) in a dynamic environment driven by solar thermal radiation (Qrad) and photosynthetically active radiation (PAR), wind speed (u), temperature (T), vapor pressure deficit (VPD), and soil water potential (ψsoil). Water flows through the plant (blue arrows) along a gradient in water potential (∇→ψ). Zones on the leaves infiltrated with AquaDust serve as reporters of the local leaf water potential, ψleaf, via a short (∼30 s), minimally invasive measurement of FRET efficiency (ζ) with a leaf clamp. (B) Schematic representations of infiltration of a suspension of AquaDust and of the distribution of AquaDust within the cross-section of a leaf. AquaDust passes through the stomata and localizes in the apoplastic spaces within the mesophyll; the particles are excluded from symplastic spaces and the vascular bundle. (C) Schematic diagrams showing mechanism of AquaDust response: The swollen, “wet” state when water potential in its local environment, ψenv=0 (i.e., no stress condition), results in low FRET between donor (green circles) and acceptor (yellow circles) dye (Upper); and the shrunken, “dry” state when ψenv<0 (i.e., stressed condition) results in high FRET between fluorophores, thereby altering the emission spectra (Lower). (D) Fluorescent dyes were chosen to minimize reabsorption of AquaDust emission from chlorophyll; comparison of representative fluorescent emission from AquaDust (donor peak at 520 nm and acceptor peak at 580 nm) with the absorption spectra of chlorophyll and autofluorescence of maize leaf.Due to the recognized importance of water potential in controlling plant function, plant scientists have spent considerable effort devising accurate and reliable methods to measure water potential of the soil, stem, and leaf (6). Of these, plant water potentials, and particularly leaf water potential (ψleaf), represent valuable indicators of plant water status because they integrate both environmental conditions (e.g., soil water availability and evaporative demand) and plant physiological processes (e.g., root water uptake, xylem transport, and stomatal regulation) (7, 8). To date, techniques to measure ψleaf remain either slow, destructive, or indirect. The current tools (e.g., Scholander pressure chamber, psychrometer, and pressure probe) involve disruption of the tissue, the microenvironment, or both (9–11). For example, the widely used pressure chamber requires excision of leaves or stems for the measurement of ψleaf. Other techniques, such as stem and leaf psychrometry, require intimate contact with the tissue, and accurate and repeatable measurements are difficult to obtain (9, 12). These limitations have hindered the study of spatiotemporal water-potential gradients along the SPAC and the development of high-throughput strategies to phenotype based on tissue water potential (13). Additionally, current methods for measuring ψleaf provide averages over tissues in the leaf. This characteristic makes the dissection of water relations on subleaf scales challenging, such that important questions remain, for example, about the partitioning of hydraulic resistances within leaves between the xylem and mesophyll (14–16).These outstanding challenges in the measurement of water status in planta motivated us to develop the measurement strategy presented here, AquaDust, with the following characteristics: 1) Minimally disruptive: Compatible with simple, rapid measurements on intact leaves. Fig. 1A presents our approach, in which AquaDust reporters infiltrated into the mesophyll of the leaf provide an externally accessible optical signal that correlates with the local water potential. 2) Localized: allowing for access to the values of water potential at a well-defined location along the path of transpiration in the leaf tissue. Fig. 1B shows a schematic representation of AquaDust particles localized in the apoplastic volume within the mesophyll, at the end of the hydraulic path for liquid water within the plant. 3) Sensitive and specific: capable of resolving water potentials across the physiologically relevant range (∼−3<ψ<0 MPa) and with minimal sensitivity to other physical (e.g., temperature) and chemical (e.g., pH) variables. Fig. 1C presents a schematic representation of an AquaDust particle formed of hydrogel, a highly tunable material that undergoes a structural response to changes in local water potential (swollen when wet; collapsed when dry). We couple the swelling behavior of the particle to an optical signal via the incorporation of fluorescence dyes (green and yellow circles in Fig. 1C) that undergo variable Förster Resonance Energy Transfer (FRET) as a function of spatial separation. Fig. 1D presents typical AquaDust spectra at high (wet; green curve) and low (dry; yellow curve) water potentials. A change in water potential leads to a change in the relative intensity of the two peaks in the AquaDust spectrum, such that the relative FRET efficiency, ζ=f(ID,IA), can serve as a measure of water potential. 4) Inert: nondisruptive of the physiological properties of the leaf (e.g., photosynthetic capacity, transpiration rate, etc.).In this paper, we present the development, characterization, and application of AquaDust. We show that AquaDust provides a robust, reproducible response of its fluorescence spectra to changes in leaf water potential in situ and across the usual physiological range. We apply our approach to quantify the spatial gradients of water potential along individual leaves undergoing active transpiration and across a range of soil water potentials. With these measurements, we show that the localization of AquaDust in the mesophyll allows us to quantify the importance of hydraulic resistances outside the xylem. We further use AquaDust to measure the diurnal dynamics of ψleaf under field conditions, with repeated measurements on individual, intact leaves. These measurements demonstrate the field-readiness of our techniques and validate the leaf hydraulic model we have developed. We conclude that AquaDust offers a powerful basis for tracking, spatially and temporally, water potential in planta to study the mechanisms by which it couples to both biological and physical processes to define plant function.     

Effect of ethylene glycol dimethacrylate on swelling and on metformin hydrochloride release behavior of chemically crosslinked pH–sensitive acrylic acid–polyvinyl alcohol hydrogel

Background

The present work objective was to prepare and to observe the effect of ethylene glycol dimethacrylate on swelling and on drug release behavior of pH-sensitive acrylic acid–polyvinyl alcohol hydrogel.

Methods

In the present work, pH sensitive acrylic acid–polyvinyl alcohol hydrogels have been prepared by free radical polymerization technique in the presence of benzoyl peroxide as an initiator. Different crosslinker contents were used to observe its effect on swelling and on drug release. Dynamic and equilibrium swelling studies of prepared hydrogels were investigated in USP phosphate buffer solutions of pH 1.2, 5.5, 6.5 and 7.5 with constant ionic strengths. Hydrogels were evaluated for polymer volume fraction, solvent interaction parameter, molecular weight between crosslinks, number of links per polymer chain, diffusion coefficient, sol–gel fraction and porosity. To demonstrate the release pattern of the drug, zero-order, first-order, higuchi and korsmeyer-peppas models were applied. Quality and consistency of hydrogels was examined by FTIR and surface morphology of hydrogels was examined by SEM.

Results

Decrease in swelling and in drug release was seen by increasing content of ethylene glycol dimethacrylate. A remarkable high swelling was observed at high pH indicating the potential of this hydrogel for delivery of drugs to intestine. By increasing the concentration of ethylene glycol dimethacrylate, porosity decreased. Order of release was observed first order in all cases and the mechanism was non–fickian diffusion. FTIR confirmed the formation of network. SEM results showed the incorporation of drug.

Conclusion

The prepared hydrogels can be suitably used for targeted drug delivery to the intestine.     

In vitro and in vivo ocular safety and eye surface permanence determination by direct and Magnetic Resonance Imaging of ion-sensitive hydrogels based on gellan gum and kappa-carrageenan

Gellan gum, kappa-carrageenan and alginates are natural polysaccharides able to interact with different cations that can be used to elaborate ion-activated in situ gelling systems for different uses. The interaction between fluid solutions of these polysaccharides and cations presents into the tear made these biopolymers very interesting to elaborate ophthalmic drug delivery systems. The main purpose of this study is to evaluate the ability of mixtures of these polymers to obtain ion-activated ophthalmic in situ gelling systems with optimal properties for ocular use. To achieve this purpose different proportion of the biopolymers were analyzed using a mixture experimental design evaluating their transparency, mechanical properties and bioadhesion in the absence and presence of simulated tear fluid. Tear induces a rapid sol-to-gel phase transition in the mixtures forming a consistent hydrogel. The solution composed by 80% of gellan gum and 20% kappa-carrageenan showed the best mechanical and mucoadhesive properties. This mixture was evaluated for rheological behavior, microstructure, cytotoxicity, acute corneal irritancy, ex-vivo and in vivo ocular toxicity and in vivo corneal contact time using Magnetic Resonance Images (MRI) techniques. Result indicates that the system is safe at ophthalmic level and produces an extensive ocular permanence higher than 6 h.