大鼠腹腔脂肪干细胞的分离培养及诱导成骨

背景：脂肪干细胞取材方便、增殖旺盛、具有多向分化潜能,有望取代骨髓间充质干细胞而成为新一代组织工程的种子细胞。然而,脂肪干细胞的分离培养仍存在诸多困难与不足。目的：优化脂肪干细胞的分离培养方法,并鉴定其成骨分化潜能。方法：选取200g成年雌性大鼠1只,无菌环境下切取大鼠肾脏、子宫周围及腹后外侧白色脂肪组织,多次胶原酶消化法分离消化,低糖培养基培养脂肪干细胞,倒置显微镜下观察脂肪干细胞的形态变化及增殖能力。采用成骨诱导培养液对第3代细胞进行成骨诱导,并采用碱性磷酸酶、茜素红染色方法进行鉴定。结果与结论：脂肪干细胞形态以长梭形为主,增殖活跃呈旋涡状生长。经成骨诱导10d后,碱性磷酸酶染色为阳性;成骨诱导28d后,茜素红染色阳性。提示采用多次酶消化法得到的大鼠腹腔源性脂肪干细胞在体外易于分离培养,可以稳定传代。在一定条件诱导下,可以向成骨细胞分化。采用以上方法进行脂肪干细胞的分离培养可以为组织工程提供大量、优质的种子细胞。     

Histological and elemental analyses of impaired bone mineralization in klotho-deficient mice

The klotho gene-deficient mouse is known as an animal model for an accelerated gerontic state, mimicking osteoporosis, skin atrophy, ectopic calcification, and gonadal dysplasia. To elucidate the influence of klotho deficiency on bone mineralization, we examined the ultrastructures of osteoblasts and bone matrices in addition to performing the elemental mapping of calcium, phosphorus, and magnesium in the bone. Under anesthesia, 4- and 5-week-old klotho-deficient mice (klotho(-/-)mice) and their wild-type littermates were perfused with either 4% paraformaldehyde for light microscopic observation or 4% paraformaldehyde and 0.0125% glutaraldehyde for electron microscopic observation. The femurs and tibiae were processed for both observations. Paraffin sections were subject to alkaline phosphatase and tartrate resistant acid phosphatase histochemistry. Semithin and ultrathin sections obtained from epoxy resin-embedded specimens were used for detecting mineralization - according to von Kossa's staining method - and for elemental mapping by electron probe micro-analyzer, respectively. Alkaline phosphatase-positive plump osteoblasts adjacent to the growth plate normally developed cell organelles in the klotho(-/-)metaphyses. This, however, contrasted with the flattened osteoblasts covering the metaphyseal trabeculae and accompanied by small tartrate resistant acid phosphatase-positive osteoclasts. The wild-type mice displayed the mineralized matrix at the zone of hypertrophic chondrocyte of the growth plate and well-mineralized metaphyseal trabeculae parallel to the longitudinal axis of the bone. Alternatively, the klotho(-/-)mice demonstrated a thick mineralized matrix from the proliferative zone of the growth plate as well as the large non-mineralized area in the metaphyseal trabeculae. Consistently, electron probe micro-analysis verified sporadic distributions of higher or lower concentrations of calcium and phosphorus in each trabecule of the klotho(-/-)mice. The distribution of magnesium, however, was almost uniform. Under transmission electron microscopy, osteoblasts on the metaphyseal trabeculae displayed less-developed cell organelles in the klotho(-/-)mice. Thus, the klotho deficiency appears not only to reduce osteoblastic population, but also to disturb bone mineralization.     

黄芪多糖对大鼠原代成骨细胞的影响及其机制研究

目的 研究黄芪多糖对体外培养大鼠原代成骨细胞增殖、分化及矿化的影响及其作用机制。方法 体外培养的新生SD大鼠颅骨原代成骨细胞体系中分别加入不同质量浓度（0.1、0.3、1、3、10、30、100 μg/mL）的黄芪多糖,24、48 h后MTT法检测细胞增殖,碱性磷酸酶（AKP）活性检测法检测细胞分化,茜素红染色法观察黄芪多糖10 μg/mL对细胞矿化的影响,Western blotting法检测黄芪多糖1、10 μg/mL作用于细胞24 h后,对细胞中骨形成蛋白（BMP-2）的表达、MAPK信号通路中关键蛋白ERK、P38、p-ERK、p-P38等表达的影响。结果 黄芪多糖能剂量相关地促进大鼠原代成骨细胞的增殖、分化及矿化,同时上调BMP-2、p-ERK、p-P38蛋白的表达,提高p-ERK/ERK、p-P38/P38值。结论 黄芪多糖可通过促进BMP-2的表达、上调其下游的ERK MAPK和P38 MAPK的磷酸化水平来促进成骨细胞增殖、分化。     

Control of peptide nanotube diameter by chemical modifications of an aromatic residue involved in a single close contact

Supramolecular self-assembly is an attractive pathway for bottom-up synthesis of novel nanomaterials. In particular, this approach allows the spontaneous formation of structures of well-defined shapes and monodisperse characteristic sizes. Because nanotechnology mainly relies on size-dependent physical phenomena, the control of monodispersity is required, but the possibility of tuning the size is also essential. For self-assembling systems, shape, size, and monodispersity are mainly settled by the chemical structure of the building block. Attempts to change the size notably by chemical modification usually end up with the loss of self-assembly. Here, we generated a library of 17 peptides forming nanotubes of monodisperse diameter ranging from 10 to 36 nm. A structural model taking into account close contacts explains how a modification of a few Å of a single aromatic residue induces a fourfold increase in nanotube diameter. The application of such a strategy is demonstrated by the formation of silica nanotubes of various diameters.     

Physiological Impact of Palm Olein or Palm Oil in Infant Formulas: A Review of Clinical Evidence

Palm oil/olein (PO/POL) is used in infant formulas to imitate the fatty acid profile of human milk (HM) and achieve similar levels of palmitic acid (PA). However, the positions of fatty acids on the triacylglyceride differ between PO/POL and HM, which affect fat absorption and produce unintended physiological consequences. Recent papers have reviewed evidence for physiological benefits of PO/POL and beta-palmitate (sn-2-palmitate) in infant formulas. The aim of the present review is to supplement the assessment of available clinical evidence on the physiological effects of PO/POL formulas in healthy infants. We intend to focus on PO/POL and not on sn-2-palmitate, since the latter was recently extensively reviewed. Clinical evidence supports that PO/POL in infant formulas leads to a lower fat, DHA, palmitate and calcium absorption, and bone mineralization; soft stools; and growth (weight accretion) compared to formulas without PO/POL. Consequently, it seems prudent to be considerate and cautious when adding PO/POL to infant formulas. While HM is the gold standard for infant nutrition, the development of infant formula should be based on achieving positive physiological outcomes, rather than just replicating HM nutrient composition.     

壳聚糖-明胶-果胶仿生网络膜对间充质干细胞增殖和矿化的影响

目的：探讨采用壳聚糖、明胶和果胶制备的仿生网络膜对间充质干细胞（MSCs）增殖和矿化的影响,评价其用于构建组织工程骨的可行性。方法：采用仿生学方法,将壳聚糖、明胶和果胶按照一定比例制作成新型仿生网络膜。实验分为对照组（MSCs+常规培养基）、材料组（MSCs+网络膜+常规培养基）和材料+成骨诱导培养基（OS）组（MSCs+网络膜+OS培养基）。倒置相差显微镜下观察细胞形态表现,扫描电镜（SEM）观察细胞生长及细胞外基质分泌情况,MTT法检测细胞增殖情况（MSCs分为阴性对照组和材料组,分别以空白培养液和含材料的培养液培养）,茜素红染色检测细胞中钙无机物表达情况,实时聚合酶链反应（Real time-PCR）测定细胞中骨钙素（OC） mRNA和骨桥蛋白（OPN） mRNA表达水平。结果：网络膜材料呈半透明薄膜状,倒置相差显微镜下MSCs为短梭形,细胞成簇状聚集生长。SEM下观察,细胞培养第7天可见梭形细胞;培养第14天时细胞数量增多,以伪足状突起锚定于材料表面;培养第21天时,细胞聚集并分泌大量细胞外基质。材料组细胞增殖水平与阴性对照组比较差异无统计学意义（P>0.05）。茜素红染色,网络膜上细胞被染成橘红色。Real time-PCR法,材料组和材料+OS组MSCs中OC mRNA在接种后第7和14天时表达水平较低,第21天时其表达水平明显升高,达到峰值;OPN mRNA在第7天明显表达,第14天时表达水平达峰值,第21天略有下降;与对照组比较,不同时间点材料组和材料+OS组细胞中OC mRNA和OPN mRNA表达水平明显升高（P<0.01）,而材料组与材料+OS组比较差异无统计学意义（P>0.05）。结论：壳聚糖-明胶-果胶仿生网络膜具有良好的生物相容性,MSC在其表面可正常生长和增殖,在不加诱导剂的情况下可以诱导MSCs表达矿化相关的基因和蛋白。