Enhanced chondrogenic differentiation of murine embryonic stem cells in hydrogels with glucosamine

Differentiation of embryonic stem (ES) cells generally occurs after formation of three-dimensional cell aggregates, known as embryoid bodies (EBs). We have previously reported that hydrogels provide EBs a supportive environment for in vitro chondrogenic differentiation and three dimensional tissue formation [Hwang NS, et al. The Effects of three dimensional culture and growth factors on the chondrogenic differentiation of murine ES cells. Stem Cells 2006;24:284–91]. In this study, we report chondrogenic differentiation of murine ES cells encapsulated in photopolymerizing poly(ethylene-glycol)-based (PEG) hydrogels in the presence of glucosamine (GlcN), an amino monosaccharide found in chitin, glycoproteins and glycosaminoglycans such as hyaluronic acid, chondroitin sulfate and heparin sulfate. We examined the growth and differentiation of encapsulated EBs in standard chondrogenic differentiation medium containing 0-, 2-, and 10-mm GlcN. Morphometric analysis and examination of gene and protein expression indicated that treatment of hydrogel cultures with 2-mm GlcN for 21 days significantly increased EB size, levels of aggrecan mRNA, and tissue-specific extracellular matrix accumulation. GlcN can induce multiple aspects of cell behavior and optimal GlcN concentrations can be beneficial for directing the differentiation and tissue formation of ES cells.     

An investigation into the influence of hydrogel composition on swelling behavior and drug release from poly(acrylamide-co-itaconic acid) hydrogels in various media

The hydrogels prepared by free radical copolymerization of acrylamide and itaconic acid were investigated with regard to their composition and crosslinking degree to find materials with satisfactory swelling and drug release properties. Samples were characterized by measuring the swelling behavior and in vitro release of paracetamol as a model drug in aqueous media with different pH values. The two-factor, three-level experimental design and response surface methodology were applied to statistically evaluate the influence of investigated factors.     

水凝胶垫预防骨科手术患者压疮的护理

目的 探讨水凝胶垫在预防骨科手术患者压疮的护理.方法 采集2006年2月-2008年2月106例骨科股骨骨折患者实施股骨近端闭合复位交锁髓内钉内固定术(简称PFN)的患者,对其特殊的手术体位进行压疮的风险因素评估,尤其会阴部受压部位,制定护理对策,使用水凝胶垫进行保护,预警干预压疮的发生,减少并发症.结果 106例骨科PFN手术患者中对照组51例,压疮发生率为70%;干预组55例,压疮发生率为38%;两组间的差异有统计学意义(P<0.01).结论 通过使用水凝胶垫,不同程度降低手术患者压疮发生率.     

Cyclodextrin-based supramolecular architectures: Syntheses, structures, and applications for drug and gene delivery

The supramolecular structures formed between cyclodextrins (CDs) and polymers have inspired interesting developments of novel supramolecular biomaterials. This review will update the recent progress in studies on supramolecular structures based on CDs and block copolymers, followed by the design and synthesis of CD-based supramolecular hydrogels and biodegradable polyrotaxanes for potential controlled drug delivery, and CD-containing cationic polymers and cationic polyrotaxanes for gene delivery. Supramolecular hydrogels based on the self-assembly of the inclusion complexes between CDs with biodegradable block copolymers could be used as promising injectable drug delivery systems for sustained controlled release of macromolecular drugs. Biodegradable polyrotaxanes with drug-conjugated CDs threaded on a polymer chain with degradable end-caps could be interesting supramolecular prodrugs for controlled and targeting delivery of drugs. CD-containing cationic polymers as gene carriers showed reduced cytotoxicity than non-CD-containing polymer counterparts. More importantly, the polyplexes of CD-containing cationic polymers with DNA could be pegylated through a supramolecular process using inclusion complexation between the CD moieties and a modified PEO. Finally, new cationic polyrotaxanes composed of multiple oligoethylenimine-grafted CDs threaded and end-capped on a block copolymer chain were designed and synthesized as a new class of polymeric gene delivery vectors, where the chain-interlocked cationic cyclic units formed an integrated supramolecular entity to function as a macromolecular gene vector. The development of the supramolecular biomaterials through inclusion complexation has opened up a new approach for designing novel drug and gene delivery systems, which may have many advantages over the systems based on the conventional polymeric materials.     

Macroporous poly(sucrose acrylate) hydrogel for controlled release of macromolecules

We have studied the controlled release of proteins from poly(sucrose acrylate) hydrogels. The hydrogels were prepared by a two-step procedure in which sucrose was first acylated to sucrose-1′-acrylate followed by free radical polymerization. By adjusting the cross-link ratio and initial monomer concentration, the swelling ratio of the hydrogel was varied from five to 28. The mechanical strength of these hydrogels was comparable to that of other hydrogels with approximately the same swelling ratio. Scanning electron micrographs and mesh size calculations indicate that the hydrogel is macroporous, suggesting it may be suitable for a variety of biomedical applications. The release kinetics of β-lactoglobulin, bovine serum albumin and γ-globulin were studied as a function of initial monomer concentrations for the sucrose-based hydrogel. All of the release profiles were characterized by an initial burst of protein in the first 25 h followed by a long period of sustained release (s> 500 h). The magnitude of the initial burst was reduced by increasing the initial monomer concentration and by increasing the molecular weight of the protein. A quantitative model based on the heterogeneous nature of the hydrogel was developed to explain the observed release kinetics.     

Cyclodextrin controlled release of poorly water-soluble drugs from hydrogels

The effect of 2-hydroxypropyl-β-cyclodextrin and γ-cyclodextrin on the release of ibuprofen, ketoprofen and prednisolone was studied. Stability constants calculated for inclusion complexes show size dependence for complexes with both cyclodextrins. Hydrogels were prepared by ultraviolet irradiation and release of each model drug was studied. For drugs formulated using cyclodextrins an increase in the achievable concentration and in the release from hydrogels was obtained due to increased solubility, although the solubility of all γ-cyclodextrin complexes was limited. The Load also was increased by adjusting pH for the acidic drugs and this exceeds the increase obtained with γ-cyclodextrin addition.     

Dentin primer based on a highly functionalized gelatin-methacryloyl hydrogel

Gelatin-methacryloyl hydrogels (GelMA) have demonstrated their utility as scaffolds in a variety of tissue engineering applications.ObjectivesIn this study, a highly functionalized GelMA hydrogel was synthesized and assessed for degree of functionalization. As the proposed GelMA hydrogel was coupled to a visible-light photoinitiator, we hypothesized it might serve as base to formulate a model dentin primer for application in restorative dentistry.MethodsGelMA was mixed with photoinitiator lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP), photopolymerized for 0–40 s using a dental light-curing device and tested for extrudability, degree of photo-crosslinking (DPxlink), water sorption/solubility/swelling (WS/SL/SW) and apparent modulus of elasticity (AE). Model dentin primer was prepared by mixing GelMA+LAP with a primer of a commercial three-step etch-and-rinse adhesive. After application of GelMA-based primer to acid-etched dentin, samples were bonded with correspondent adhesive agent, photopolymerized and had their immediate bond strength compared to control samples primed and bonded with the same commercial material.ResultsExtrudability of hydrogel was confirmed using a microsyringe to write the acronym “CDMI”. DPxlink of GelMA+LAP changed significantly as a function of photopolymerization time (20 s < 30 s ≤ 40 s). WS, SL and SW were significantly reduced in hydrogels polymerized for 30 and 40 s. AE of hydrogels varied significantly as a function of photopolymerization time (20 s < 30 s ≤ 40 s; 20 s 3 40 s). Bond strength of dentin primed with GelMA-based primer was lower (～29.3 MPa) but not significantly of that of control (～34.6 MPa).ConclusionsOptimization of a GelMA-based dentin primers can lead to the development of promising biomimetic adhesives for dentin rehabilitation.     

Wound healing properties of Carica papaya latex: In vivo evaluation in mice burn model

Ethnopharmacological relevance

Carica papaya is traditionally used to treat various skin disorders, including wounds. It is widely used in developing countries as an effective and readily available treatment of various wounds, particularly burns.

The aim of the study

This study was aimed at investigating the healing efficiency of papaya latex formulated as 1.0 and 2.5% hydrogels.

Materials and methods

Burns were induced in Swiss albino mice divided into five groups as following; Group-I (negative control) received no treatment. Group-II was treated with Carbopol 974P NF empty gel. Groups-III and -IV were treated with Carbopol gel containing 1.0 and 2.5% of dried papaya latex, respectively. Group-V (positive control) received the standard drug (silver sulphadiazine and chlorhexidine gluconate cream). The efficacy of treatment was evaluated based on the hydroxyproline content, wound contraction and epithelialization time.

Results

Hydroxyproline content was found to be significantly increased in the Group-III. Significant increase in percentage wound contraction was observed from day 12 in Group-IV and from day 20 in Groups-III and -V. The epithelialization time was found to be the shortest in Group-IV.

Conclusion

It may be concluded that papaya latex formulated in the Carbopol gel is effective in the treatment of burns and thus supports its traditional use.     

制备负载细胞可注射微球及体外评价北大核心

背景:利用生物材料作为细胞载体能够提供3D培养微环境,支持细胞活力和功能,并有可能扩大细胞治疗的数量和治疗效果,因此寻找一个合适的生物材料显得十分重要。目的:制备可注射甲基丙烯酰化明胶多孔水凝胶微球,探究其生物相容性及负载细胞用于组织工程的潜力。方法:利用微流控技术制备可注射甲基丙烯酰化明胶多孔水凝胶微球,表征微球的微观形貌与硬度。分别采用正常培养基(对照组)与微球浸提液(实验组)培养MC3T3-E1细胞,利用CCK-8法检测细胞增殖,活死细胞染色法检测细胞存活。将微球与CD3^(+)T细胞共培养,以单独培养的CD3^(+)T细胞为对照,光学显微镜下观察微球是否对T细胞活化产生影响,Dapi染色观察微球负载T细胞的形态,流式细胞术验证与微球共培养是否对CD4^(+)T细胞和CD8^(+)T细胞的比例产生影响。结果与结论:①倒置显微镜下可见,冻干前后的微球均保持高度分散且大小均一,直径大小满足可注射条件;扫描电镜下可见,冻干后的微球为多孔结构,孔隙均匀分布;微球的弹性模量为(9.76±2.04)kPa。②CCK-8检测与活死细胞染色显示,两组MC3T3-E1细胞的增殖趋势与增殖活性无明显差别。③光学显微镜下可见,培养2 d时微球未引起CD3^(+)T细胞的活化,也未干预CD3^(+)T细胞的活化,CD3^(+)T细胞分布于微球表面及孔隙内。④流式细胞术检测显示,微球未影响CD4^(+)T细胞和CD8^(+)T细胞的比例。⑤结果表明,通过微流控技术制备了一种可注射甲基丙烯酰化明胶多孔微球,其具有良好的生物相容性且不会对细胞产生不利影响,是一种在组织工程中具有广阔应用前景的生物材料。     

Nanoencapsulation of rice bran oil increases its protective effects against UVB radiation-induced skin injury in mice

Excessive UV-B radiation by sunlight produces inflammatory and oxidative damage of skin, which can lead to sunburn, photoaging, and cancer. This study evaluated whether nanoencapsulation improves the protective effects of rice bran oil against UVB radiation-induced skin damage in mice. Lipid-core nanocapsules containing rice bran oil were prepared, and had mean size around 200 nm, negative zeta potential (∼−9 mV), and low polydispersity index (<0.20). In order to allow application on the skin, a hydrogel containing the nanoencapsulated rice bran oil was prepared. This formulation was able to prevent ear edema induced by UVB irradiation by 60 ± 9%, when compared with a hydrogel containing LNC prepared with a mixture of medium chain triglycerides instead of rice bran oil. Protein carbonylation levels (biomarker of oxidative stress) and NF-κB nuclear translocation (biomarker of pro-inflammatory and carcinogenesis response) were reduced (81% and 87%, respectively) in animals treated with the hydrogel containing the nanoencapsulated rice bran oil. These in vivo results demonstrate the beneficial effects of nanoencapsulation to improve the protective properties of rice bran oil on skin damage caused by UVB exposure.