Acceleration of de novo bone formation with a novel bioabsorbable film: a histomorphometric study in vivo

Objective:  Different types of barrier membranes have been used in periodontal applications for the technology of guided tissue regeneration (GTR). The aim of this study was to characterize the biological effect of novel calcium alginate film (CAF) on bone tissue regeneration by using rabbit mandible defects model.
Methods:  A critical size defect (5 mm in diameter) was created in the bilateral corner of mandible of 45 adult rabbits. The defects were covered with CAF served as the experimental group, or conventional collagen membrane (CCM) or left empty as the controls. Animals were killed after 1, 2, 4, 6 and 8 weeks. Morphological and histomorphometric studies were performed to evaluate their bone regeneration pattern and biological effects.
Results:  Histological sections showed that bone regeneration pattern was centripetal in growth from defect rim. The quantitative histometry analysis revealed a significantly greater percentage of newly generated bone in CAF defects than that in CCM defects and empty defects from 2 to 6 weeks post-operation ( P  < 0.01). After 6 and 8 weeks, significantly more mature lamella bone had formed with CAF than with CCM. Empty control defects showed bone formation starting from the defect margins and incomplete healing even after 8 weeks.
Conclusion:  The CAF guided early bone growth and appeared more effective as a bioabsorbable GTR membrane than CCM. This study with mandible defect model suggests that bone defects augmented with CAF may offer most promising results from a histological and histomorphometric perspective.     

Physical properties and compatibility with dental stones of current alginate impression materials

This study examined physical properties and compatibility with dental stones of two types of alginate impression materials. Five powder-type alginate impression materials (Alginoplast EM, Aroma Fine, Algiace Z, Coe Alginate, Jeltrate Plus) and a paste-type alginate impression material (Tokuso AP-1) were used. The dynamic viscosity immediately after mixing was measured by means of a controlled-stress rheometer. The gelation times were determined according to Japanese Industrial Standards (JIS) T6505, and recovery from deformation, strain in compression and compressive strength were determined according to the International Organization for Standardization (ISO) specification 1563. Detail reproduction and surface roughness of type III dental stones (New Plastone, New Sunstone) and a type IV dental stone (Die Stone) were evaluated using a ruled test block as specified in the ISO specification 1563 and a profilometer, respectively. The alginate impression materials evaluated in this study were all in compliance with the ISO specification 1563 and JIS T6505. The alginate impression materials had similar mechanical properties after gelation, whilst a wide range of dynamic viscosity immediately after being mixed, gelation times and compatibility with dental stones were found among the materials. The paste-type material had a higher dynamic viscosity and a shorter gelation time than the powder-type materials. The best surface quality was obtained with the paste-type material/type III dental stone cast combinations. The materials should be selected in consideration of initial flow, setting characteristics and compatibility with dental stones. The results suggested that a paste-type material would better meet the requirements of an alginate impression material.     

海藻酸钙膜引导兔颌骨缺损骨再生的对照实验

目的：比较观察两种国前可吸收性生物膜对引导性骨再生的影响，探讨海藻酸钙膜在骨缺损应用中的优势。方法：以家兔为研究对象，在其双侧下颌角前切迹外造 成洞形骨缺损，实验侧覆盖海藻酸钙膜，对照侧覆盖胶元膜，分别在术后1、2、4、6、8周时取出下颌骨，进行大体观察，X线观察、组织学观察、电镜观察以及免疫组化染色后对3种骨诱导因子含量进行测量。结果：海藻酸钙膜4－6周吸收，胶元膜6－8周吸收；前者组织反应程度轻，后者反应程度重；术后6周内实验侧BMP、骨钙素、VEGF总体含量明显高于对照侧（P＜0．01）；电镜下实验侧胶原纤维和骨小梁比对照侧出现早、多、有序。结论：海藻酸钙膜比已较广泛研究和采用的胶元膜效果更好。     

Influence of ionic crosslinkers (Ca2+/Ba2+/Zn2+) on the mechanical and biological properties of 3D Bioplotted Hydrogel Scaffolds

Three dimensional (3D) bioplotting requires appropriate crosslinkers to crosslink the hydrogel precursor while simultaneously maintaining the viability of embedded cells. However, the evaluation and comparison of various types of crosslinkers in bioplotting remains underexplored to date. This paper presents our study of the influence of three ionic crosslinkers—calcium chloride (CaCl₂), barium chloride (BaCl₂), and zinc chloride (ZnCl₂)—on the mechanical and biological properties of 3D bioplotted alginate scaffolds. The scaffold mechanical properties characterized included the elastic modulus, swelling, and degradation while the biological properties considered included Schwann cell viability and surface morphology. The mechanical and biological properties of the bioplotted scaffolds were both dependent on the crosslinkers used for fabrication; specifically, crosslinking ions resulted in the elastic modulus of the hydrogels decreasing in the order BaCl₂>CaCl₂>ZnCl₂ over 42 days while Schwann cell viability decreased in the order CaCl₂>BaCl₂>ZnCl₂ over 7 days. Taken together, these results offer insights that are effective in terms of manipulating the 3D bioplotting process so as to tune and optimize the mechanical and biological performance of the plotted scaffolds for tissue engineering applications.     

海藻酸钠微球肾动脉栓塞的动物实验研究

目的评价海藻酸钠微球栓塞剂在实验动物体内的栓塞性能、降解性和生物相容性。方法实验动物为中华小型猪8头,首先利用海藻酸钠微球全部行左肾动脉栓塞,分别于栓塞后的1、2、4、8周随机抽取其中2头实验动物行动脉造影与CT复查肾脏栓塞后变化,随后处死实验动物,对栓塞肾脏行组织学检查,同时对实验动物栓塞前后的实验室检查指标进行比较。结果栓塞后即刻动脉造影显示肾动脉阻断,1周后,肾动脉分支有再通,随着时间的延长,动脉再通越来越明显;CT复查可见被栓塞肾脏内有梗死区,肾脏逐渐变小;一直到栓塞后4周,组织学检查均可见小动脉内微球,动脉周围有炎症反应,并可见肾实质梗死灶;实验动物栓塞前后的各项实验室检查指标无显著性差异（P〉0.05）。结论海藻酸钠微球具有明确的栓塞效果,体内可降解,生物相容性良好。     

A型肉毒杆菌毒素的壳聚糖／海藻酸钠缓释微囊研制和药物的体外释放速率研究

目的：研制包裹A型肉毒杆菌毒素的壳聚糖/海藻酸钠微囊,并测定其体外药物释放动力学。方法：采用注射器滴注法制成包裹A型肉毒杆菌毒素的壳聚糖/海藻酸钠微囊混悬液。采用高效液相色谱法测定A型肉毒杆菌毒素的标准曲线,每隔2周测定微囊所包裹的A型肉毒杆菌毒素体外释放浓度。结果：微囊形态为圆形透明颗粒状,粒径在1mm左右。用SPSS统计软件进行分析微囊中A型肉毒杆菌毒素的体外每2周释放量,显示药物累积释放量与时间之间为直线关系,基本符合药物零级释放动力学。结论：滴注法制备包裹A型肉毒杆菌毒素的壳聚糖/海藻酸钠缓释微囊制作方法简便,其药物体外释放稳定。     

Incorporation of magnesium ions into photo‐crosslinked alginate hydrogel enhanced cell adhesion ability

Photo‐crosslinked alginate hydrogel attracts wide interest in tissue engineering because of its excellent controllability and stability. However, its highly hydrophilic property makes cell adhesion difficult. Plenty of studies have confirmed that magnesium ions (Mg²⁺) can efficiently improve the attachment of osteoblasts. In this study, for the first time, we fabricated a durable, crosslinked, alginate hydrogel with a dual‐crosslinking network. Photo‐crosslinked alginate hydrogel was chosen as the basic backbone, and various amounts of Mg²⁺ were incorporated into the hydrogel through ionic crosslinking. The results showed that the physicochemical properties of the hydrogels, including surface structure, composition, swelling ratio, ion release and elastic modulus, could be well tuned by controlling the amount of Mg²⁺ incorporated. In addition, a certain amount of Mg²⁺ significantly improved the attachment and spread of osteoblasts on the hydrogels. These characteristics make Mg²⁺‐incorporated photo‐crosslinked alginate hydrogel a promising scaffold for bone tissue engineering. Copyright © 2015 John Wiley & Sons, Ltd.     

Immobilization of sodium alginate sulfates on polysulfone ultrafiltration membranes for selective adsorption of low-density lipoprotein

A novel method for the immobilization of sodium alginate sulfates (SAS) on polysulfone (PSu) ultrafiltration membranes to achieve selective adsorption of low-density lipoprotein (LDL) was developed, which involved the photoinduced graft polymerization of acrylamide on the membrane and the Hofmann rearrangement reaction of grafted acrylamide followed by chemical binding of SAS with glutaraldehyde. The surface modification processes were confirmed by attenuated total reflectance Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy characterization. Zeta potential and water contact angle measurements were performed to investigate the surface charge and wettability of the membranes. An enzyme-linked immunosorbent assay was used to measure the binding of LDL on plain and modified PSu membranes. It was found that the PSu membrane immobilized with sodium alginate sulfates (PSu-SAS) greatly enhanced the selective adsorption of LDL from protein solutions and the absorbed LDL could be easily eluted with sodium chloride solution, indicating a specific and reversible binding of LDL to SAS, mainly driven by electrostatic forces. Furthermore, the PSu-SAS membrane showed good blood compatibility as examined by platelet adhesion. The results suggest that the PSu-SAS membranes are promising for application in simultaneous hemodialysis and LDL apheresis therapy.