髓核细胞诱导骨髓间充质干细胞向髓核方向的分化

背景：国内外已有很多文献相继报道了用骨髓间充质干细胞-藻酸盐复合植入材料来修复大鼠退变的腰椎间盘,但尚缺少对此复合物与正常髓核细胞之间的各项生物学指标的比较。 目的：在Transwell非接触共培养条件下,研究髓核细胞对骨髓间充质干细胞的诱导作用。 方法：全骨髓法培养大鼠骨髓间充质干细胞并鉴定,取第3代骨髓间充质干细胞及髓核细胞复合藻酸盐接种于Transwell共培养系统中,上室接种骨髓间充质干细胞藻酸盐复合物,下室接种髓核细胞藻酸盐复合物,共培养7 d后回收上层骨髓间充质干细胞。 结果与结论：RT-PCR方法检测共培养组Ⅱ型胶原、Sox-9和多功能蛋白聚糖的mRNA表达均接近正常髓核细胞。说明共培养条件下髓核细胞能诱导骨髓间充质干细胞向髓核方向分化。     

Alginate encapsulation supports the growth and differentiation of human primordial follicles within ovarian cortical tissue

Purpose

In vitro follicle growth (IVFG) is an investigational fertility preservation technique in which immature follicles are grown in culture to produce mature eggs that can ultimately be fertilized. Although progress has been made in growing primate primary and secondary follicles in vitro, it has been a relatively greater challenge to isolate and culture primordial follicles. The purpose of this study was to develop methods to grow human primordial follicles in vitro using alginate hydrogels.

Methods

We obtained human ovarian tissue for research purposes through the National Physicians Cooperative from nationwide sites and used it to test two methods for culturing primordial follicles. First, primordial follicles were isolated from the ovarian cortex and encapsulated in alginate hydrogels. Second, 1 mm × 1 mm pieces of 500 μm-thick human ovarian cortex containing primordial follicles were encapsulated in alginate hydrogels, and survival and follicle development within the tissue was assessed for up to 6 weeks.

Results

We found that human ovarian tissue could be kept at 4 °C for up to 24 h while still maintaining follicle viability. Primordial follicles isolated from ovarian tissue did not survive culture. However, encapsulation and culture of ovarian cortical pieces supported the survival, differentiation, and growth of primordial and primary follicles. Within several weeks of culture, many of the ovarian tissue pieces had formed a defined surface epithelium and contained growing preantral and antral follicles.

Conclusions

The early stages of in vitro human follicle development require the support of the native ovarian cortex.     

海藻酸钙凝胶微球的制备和pH依赖性溶胀

利用海藻酸钠溶液与氯化钙溶液发生胶凝反应，本文用滴制的方法制备了海藻酸钙凝胶微球，并对制备的处方和工艺进行了探讨，同时考察了海藻酸钙凝胶微球的特征和溶胀特性。干燥的凝胶微球在不同pH的水性介质中溶胀特性不同。海藻酸钙凝胶微球的这种溶胀的pH敏感性，使其能成为口服药物缓释制剂的载体。     

Preparation and properties of a pH sensitive carrier based on three kinds of polymer blend to control the release of 5-amino salicylic acid

Abstract

Context: High concentration of 5-amino salicylic acid (5-ASA) in the distal ileum and colon is necessary for the treatment of inflammatory bowel disease (IBD). The control of small molecules, drugs, released from a polymeric matrix remains a great challenge.

Objective: To study the preparation and properties of a pH-sensitive carrier for targeting delivery of 5-ASA.

Materials and methods: The carrier was prepared by ternary blends method based on polyvinyl alcohol (PVA), sodium alginate (SA) and polylactic acid. It was characterized by infrared spectrometry and scanning electronic microscopy. The adsorption and release of 5-ASA in different pH media were investigated.

Results: We found out the best ratio of the materials for synthetic carrier. The vector exhibited good performance by the controlled release of the target drug experiment. The adsorption capacity of the carrier for 5-ASA was 70.34% in phosphate buffer saline at pH 1.00, and the release rate was 100.49% in phosphate buffer solution at pH 6.80.

Discussion and conclusion: PVA is vector backbone of the carrier, and SA plays key role in its pH performance. It is a promising material to effectively deliver 5-ASA to the specific sites of IBD.     

Hydrostatic pressure induces apoptosis of chondrocytes cultured in alginate beads.

The purpose of this study was to investigate the influence of hydrostatic pressure (HP) on apoptosis and expression of heat-shock protein 70 (HSP70) in chondrocytes cultured in alginate beads. Chondrocytes were isolated from the articular cartilage of rabbit joints and seeded in alginate beads. The beads in Group A were cultured for less than 24 h after being embedded with the chondrocytes, while those in Group B were cultured for 2 weeks. Both groups were exposed to HP of 10 or 50 MPa for 12 or 24 h. The beads in Groups A and B that were not exposed to HP were regarded as controls. Apoptotic cells induced by exposure to HP were quantified using the TUNEL method. Immunohistochemical analysis for HSP70 and in situ TUNEL analysis were also performed. Apoptotic chondrocytes were not observed in the control cells under atmospheric pressure, whereas apoptosis was observed in the beads in Group A, and the number of apoptotic cells increased as the duration and magnitude of HP increased. On the other hand, we observed no significant population of apoptotic cells in the beads in Group B. Chondrocytes expressing HSP70 were not TUNEL positive in the histological analysis. Excessively strong HP could evoke apoptosis when the extracellular matrix did not accumulate around the chondrocytes. HSP70 expression was related to occurrence of apoptosis that resulted from HP. These findings suggest a mechanism for the pathogenesis of cartilage degeneration in osteoarthritis.     

羊栖菜中褐藻酸钠的脱色纯化工艺及其结构成分研究

研究了羊栖菜中褐藻酸钠的脱色纯化工艺并测定了其组成与相对分子质量.结果表明褐藻酸钠脱色纯化的最佳工艺条件为3%(质量分数)甲醛溶液预浸泡,10%(质量分数)HCl溶液沉淀分离出褐藻胶,1 g/dL的Na2CO3溶液中和,10%(体积分数) NaClO溶液进行脱色.通过纯化工艺制得的褐藻酸钠的纯度为95.1%,褐藻酸钠分子中β-D-甘露糖醛酸与α-L-古罗糖醛酸的量的比值为0.75,平均聚合度DP为101,粘均相对分子质量为21 963.     

海藻酸钠的分子量与缓释作用

以盐酸普罗帕酮、盐酸地尔硫和硝酸异山梨酯为模型药物,研究它们在不同分子量的海藻酸钠骨架片中的释药规律。结果表明:海藻酸钠的分子量与释药速度间有良好的线性关系。根据这一关系可以预测已知分子量海藻酸钠的释药情况,为海藻酸钠缓释片剂的处方设计及其实际应用提供理论依据。     

利用Pseudoalteromonas elyakouii菌株发酵法生产褐藻胶寡糖培养基的改进

利用Pseudoalteromonas elyakouii菌株发酵降解相对分子质量10000左右的褐藻胶，制备褐藻胶寡糖．为了达到降低培养基成本和简化分离工艺的目的，使用（NH4）2SO4为氮源的发酵培养基来代替使用蛋白胨为氮源的发酵培养基．为了促进菌的生长和发酵产物褐藻胶寡糖的生成，在新发酵培养基中分别添加海带浸液、葡萄糖、乳糖、几种氨基酸和几种代谢中间产物（丙酮酸、柠檬酸、延胡索酸、尿素），并考察这些成分对菌生长和发酵产物褐藻胶寡糖生成的影响．研究发现：在基本培养基中和添加0．1g／L的L-谷氨酰氨、0．1g／L尿素或0．1g／L柠檬酸时可获得较高的产物浓度。     

Bone differentiation of marrow-derived mesenchymal stem cells using beta-tricalcium phosphate-alginate-gelatin hybrid scaffolds

The aim of the present study was to establish a 3D culture system for bone differentiation of mesenchymal stem cells (MSCs), using a new hybrid sponge. To manufacture the scaffold, a composite of beta-tricalcium phosphate-alginate-gelatin was prepared and cast as pellets of 1 cm diameter. The sponge was then fabricated by drying in freeze-dryer for 12 h. The porosity, mean pore size, compressive modulus and strength of the composite sponge fabricated in this study were 89.7%, 325.3 microm, 1.82 and 0.196 MPa, respectively. To establish a 3D culture system, the rat bone marrow-derived MSCs were suspended in 500 microl diluted collagen gel, loaded into the porous sponge and provided with medium with or without osteogenic supplements for 3 weeks. The day after loading, the cells appeared in the scaffold's internal spaces, where later some of them from either culture survived by anchoring on the surfaces. At the end of cultivation period, individually adhered cells from both cultures were observed to be replaced by cell aggregates, in which mineralized matrix was detected by alizarin red staining. Furthermore, RT-PCR analysis indicated that the bone-specific gene osteocalcin was expressed in cultures in both the presence and absence of the osteogenic supplements. Taken together, it seems that the studied scaffolds are cell-compatible and, more importantly, possess some osteo-inductive properties.     

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.