去卵巢大鼠骨基质明胶修复骨缺损骨痂的矿物质元素分析

应用等离子体发射光谱仪测定了去卵巢水平下骨基质明胶修复大鼠颅骨骨缺损新生骨痂的矿物质元素含量。将28只雌性SD大鼠随机分为2组。去卵巢组切除双侧卵巢，伪手术对照组保留卵巢。术后4周在颅骨上制备骨缺损并同期植入骨基质明胶。8周后，测定新生骨痂的矿物质元素含量。结果显示，去卵巢大鼠新生骨痂的S、Ca、P、Zn、Fe和Cu含量较伪手术组显著降低。实验表明雌激素水平影响骨基质明胶修复骨缺损骨痂的矿物质元素含量。     

高效液相色谱法测定全血中骨碱性磷酸酶的活力

 建立了测定全血中骨碱性磷酸酶(BALP)的高效液相色谱法(HPLC)。色谱柱为SpectraPhysicsODS反相柱,以V(0.01mol/L乙酸,pH4.8)∶V(甲醇)=70∶30的溶液为流动相,流速为0.8mL/min,检测波长为275nm。当BALP的质量浓度为8～200mg/L时,其活性对峰面积呈良好的线性关系(r=0.996),检测限为3ng。该方法简便、快速、可靠,可用于临床测定全血中的BALP。     

Intramarrow injection of β-catenin-activated,but not na?ve mesenchymal stromal cells stimulates self-renewal of hematopoietic stem cells in bone marrow

Bone marrow mesenchymal stromal cells (MSCs) have been implicated in the microenvironmental support of hematopoietic stem cells (HSCs) and often co-transplanted with HSCs to facilitate recovery of ablated bone marrows. However, the precise effect of transplanted MSCs on HSC regeneration remains unclear because the kinetics of HSC self-renewal in vivo after co-transplantation has not been monitored. In this study, we examined the effects of intrafemoral injection of MSCs on HSC self-renewal in rigorous competitive repopulating unit (CRU) assays using congenic transplantation models in which stromal progenitors (CFU-F) were ablated by irradiation. Interestingly, naïve MSCs injected into femur contributed to the reconstitution of a stromal niche in the ablated bone marrows, but did not exert a stimulatory effect on the in-vivo self-renewal of co-transplanted HSCs regardless of the transplantation methods. In contrast, HSC self-renewal was four-fold higher in bone marrows intrafemorally injected with β-catenin-activated MSCs. These results reveal that naïve MSCs lack a stimulatory effect on HSC self-renewal in-vivo and that stroma must be activated during recoveries of bone marrows. Stromal targeting of wnt/β-catenin signals may be a strategy to activate such a stem cell niche for efficient regeneration of bone marrow HSCs.     

古人类骨骼中微量元素的分析及其与古代食谱的关联

采用等离子体质谱(ICP-Ms)法对三峡地区及长江下游地区出土的古墓中的人体骨骼中的微量元素Zn、Sr、Ba、Ca进行了分析，并与原子吸收光谱(AAS)对照，结果表明：ICP-MS是骨化学微量元素分析很好的方法，它相对FAAS，具有灵敏度高，检出限低，可快速进行多元素检测等优点，对溶液中元素的检出限可达到ng/L数量级，对元素的高含量和低含量都能进行准确测量。本实验以Zn、Sr、Ba、Ca为指示剂，根据其测量结果，还对上述两地区的古人类食谱进行了初步探讨。     

Biomimetic strengthening polylactide scaffold materials for bone tissue engineering

In this paper, a new polylactide (PLA)-based scaffold composite by biomimetic synthesis was designed. The novel composite mainly consists of nano-hydroxyapatite (n-HA), which is the main inorganic content in natural bone tissue for the PLA. The crystal degree of the n-HA in the composite is low and the crystal size is very small, which is similar to that of natural bone. The compressive strength of the composite is higher than that of the PLA scaffold. Using the osteoblast culture technique, we detected cell behaviors on the biomaterial in vitro by SEM, and the cell affinity of the composite was found to be higher than that of the PLA scaffold. The biomimetic three-dimensional porous composite can serve as a kind of excellent scaffold material for bone tissue engineering because of its microstructure and properties. Translated from Journal of Hunan University (Natural Sciences), 2006, 33(2) (in Chinese)     

An injectable and biomimetic multi‐phase nanocomposite for non‐invasive bone tissue engineering: fabrication and mechanistic evaluation

An injectable, non‐hardening nanocomposite bone graft has been developed using a combination of nanohydroxyapatite as bioactive and osseointegrative material; P‐15 peptide‐modified poly(lactic‐co‐glycolic acid) (PLGA) microspheres as biomimetic and osteoinductive agent; and PLGA–poly(ethylene glycol) (PEG)–PLGA as a carrier gel. Increase in lactic acid/glycolic acid ratio of PLGA–PEG–PLGA resulted in stronger gels with a wider gelation window. Addition of 2.5‐fold nanohydroxyapatite resulted in significant changes in injectability (3.5‐fold force of injection), swelling characteristics (2.5 times swelling index), rheological (shear viscosity from 2.1 × 10¹ Pa s for NC3_700 to 1.5 × 10⁶ Pa s for NC3_73.52 and from 3.9 × 10² Pa s for NC8_700 to 3.76 × 10⁶ Pa s for NC8_732; an increase in elasticity at the level of 1–1000 kPa), and thermal properties of the nanocomposites. A mechanistic study showed that nanohydroxyapatite exhibits a high degree of association with the gel and interferes with its gelation owing to changes in hydrogen bonding interactions between C=?O of polymer chains and P–OH groups of nanohydroxyapatite with water molecules of the gel. A schematic was developed demonstrating changes in bonding interactions among constituent phases with respect to nanohydroxyapatite content emphasizing the importance of material interactions while fabricating multi‐phase nanocomposites for various biomedical applications. Copyright © 2017 John Wiley & Sons, Ltd.     

A Copolymer Scaffold Functionalized with Nanodiamond Particles Enhances Osteogenic Metabolic Activity and Bone Regeneration

Functionalizing polymer scaffolds with nanodiamond particles (nDPs) has pronounced effect on the surface properties, such as improved wettability, an increased active area and binding sites for cellular attachment and adhesion, and increased ability to immobilize biomolecules by physical adsorption. This study aims to evaluate the effect of poly(l ‐lactide‐co‐ε‐caprolactone) (poly(LLA‐co‐CL)) scaffolds, functionalized with nDPs, on bone regeneration in a rat calvarial critical size defect. Poly(LLA‐co‐CL) scaffolds functionalized with nDPs are also compared with pristine scaffolds with reference to albumin adsorption and seeding efficiency of bone marrow stromal cells (BMSCs). Compared with pristine scaffolds, the experimental scaffolds exhibit a reduction in albumin adsorption and a significant increase in the seeding efficiency of BMSCs (p = 0.027). In the calvarial defects implanted with BMSC‐seeded poly(LLA‐co‐CL)/nDPs scaffolds, live imaging at 12 weeks discloses a significant increase in osteogenic metabolic activity (p = 0.016). Microcomputed tomography, confirmed by histological data, reveals a substantial increase in bone volume (p = 0.021). The results show that compared with conventional poly(LLA‐co‐CL) scaffolds those functionalized with nDPs promote osteogenic metabolic activity and mineralization capacity. It is concluded that poly(LLA‐co‐CL) composite matrices functionalized with nDPs enhance osteoconductivity and therefore warrant further study as potential scaffolding material for bone tissue engineering.

     

Modified-Hydroxyapatite-Chitosan Hybrid Composite Interfacial Coating on 3D Polymeric Scaffolds for Bone Tissue Engineering

Three dimensional (3D) scaffolds have huge limitations due to their low porosity, mechanical strength, and lack of direct cell-bioactive drug contact. Whereas bisphosphonate drug has the ability to stimulate osteogenesis in osteoblasts and bone marrow mesenchymal stem cells (hMSC) which attracted its therapeutic use. However it is hard administration low bioavailability, and lack of site-specificity, limiting its usage. The proposed scaffold architecture allows cells to access the bioactive surface at their apex by interacting at the scaffold's interfacial layer. The interface of 3D polycaprolactone (PCL) scaffolds has been coated with alendronate-modified hydroxyapatite (MALD) enclosed in a chitosan matrix, to mimic the native environment and stupulate the through interaction of cells to bioactive layer. Where the mechanical strength will be provided by the skeleton of PCL. In the MALD composite's hydroxyapatite (HAP) component will govern alendronate (ALD) release behavior, and HAP presence will drive the increase in local calcium ion concentration increases hMSC proliferation and differentiation. In results, MALD show release of 86.28 ± 0.22. XPS and SEM investigation of the scaffold structure, shows inspiring particle deposition with chitosan over the interface. All scaffolds enhanced cell adhesion, proliferation, and osteocyte differentiation for over a week without in vitro cell toxicity with 3.03 ± 0.2 kPa mechanical strength.     

Green Synthesis of Silver Nanoparticles Using Extract of Cilembu Sweet Potatoes (Ipomoea batatas L var. Rancing) as Potential Filler for 3D Printed Electroactive and Anti-Infection Scaffolds

Electroactive biomaterials are fascinating for tissue engineering applications because of their ability to deliver electrical stimulation directly to cells, tissue, and organs. One particularly attractive conductive filler for electroactive biomaterials is silver nanoparticles (AgNPs) because of their high conductivity, antibacterial activity, and ability to promote bone healing. However, production of AgNPs involves a toxic reducing agent which would inhibit biological scaffold performance. This work explores facile and green synthesis of AgNPs using extract of Cilembu sweet potato and studies the effect of baking and precursor concentrations (1, 10 and 100 mM) on AgNPs’ properties. Transmission electron microscope (TEM) results revealed that the smallest particle size of AgNPs (9.95 ± 3.69 nm) with nodular morphology was obtained by utilization of baked extract and ten mM AgNO₃. Polycaprolactone (PCL)/AgNPs scaffolds exhibited several enhancements compared to PCL scaffolds. Compressive strength was six times greater (3.88 ± 0.42 MPa), more hydrophilic (contact angle of 76.8 ± 1.7°), conductive (2.3 ± 0.5 × 10⁻³ S/cm) and exhibited anti-bacterial properties against Staphylococcus aureus ATCC3658 (99.5% reduction of surviving bacteria). Despite the promising results, further investigation on biological assessment is required to obtain comprehensive study of this scaffold. This green synthesis approach together with the use of 3D printing opens a new route to manufacture AgNPs-based electroactive with improved anti-bacterial properties without utilization of any toxic organic solvents.