天然高分子/羟基磷灰石支架材料对成骨细胞增殖的影响

目的:为开展骨组织工程研究,建立成骨细胞与支架材料的体外复合培养模型.方法:取新生24h内的Wistar大鼠颅盖骨培养成骨细胞,并将成骨细胞以5×103/孔接种到HA/CS,HA/CS-SF两种支架材料表面常规培养,用倒置显微镜观察细胞形态,通过MTT比色法测出两种支架材料对细胞增殖的影响.结果:培养的成骨细胞呈短梭形或多角形,碱性磷酸酶染色镜下可见胞浆中棕色至黑色颗粒的为阳性细胞.通过MTT chromatometry比色法测定表明HA/CS-SF对细胞增殖有更好的作用.结论:HA/CS-SF具有作为骨组织工程支架材料的可行性.     

采用负压吸引种植技术体外构建组织工程骨

目的探讨有效体外构建高质量组织工程骨的细胞种植技术。方法将分离、培养的兔成骨细胞分别通过负压吸引种植技术(A组)及常规种植方法(B组)接种于β-磷酸三钙(β-TCP)支架,计算接种时细胞与支架材料的复合效率,种植后24h通过扫描电镜观察材料中细胞数量及分布情况。体外培养第3、7、10、14d,检测工程骨中细胞数、碱性磷酸酶(ALP)活性。3周后,免疫组化检测组织工程骨Ⅰ型胶原的分泌情况。结果 A组细胞与支架材料平均复合率、Ⅰ型胶原染色面积、各时间点细胞数及ALP活性表达均高于B组(P<0.05)。结论与传统种植方法比较,采用负压吸引种植技术能在体外形成更高质量的组织工程骨。     

骨髓来源成骨细胞复合纳米晶羟基磷灰石胶原材料培养的研究

目的 探讨纳米材料作为组织工程骨基质材料的可行性。方法 分离培养兔骨髓间充质干细胞，诱导为成骨细胞后作为种子细胞，与纳米晶羟基磷灰石胶原材料于体外联合培养，通过对复合物光镜、免疫组织化学染色及扫描电镜观察，了解细胞在材料中生长情况。结果 兔骨髓间充质干细胞可以诱导为成骨细胞，体外复合培养8天，分布于支架材料上的细胞大量分化增殖、分泌细胞外基质。结论 纳米晶羟基磷灰石胶原材料是一种构建组织工程骨的较好的支架材料。     

CS/igf-1基因复合物促骨髓基质细胞增殖及分化的研究

目的:研究壳聚糖/igf-1基因(CS/igf-1)复合物对体外培养的骨髓基质细胞(MSC)分化及增殖的影响。方法:自大鼠股骨及胫骨组织中分离培养大鼠骨髓基质细胞,以含有人igf-1基因cDNA的哺乳动物表达载体pTRacer-igf-1与壳聚糖制备成CS/igf-1复合物加入细胞培养基中进行干预;另设空白细胞组、CS/空质粒干预组及单纯CS干预组作为对照。3H-TdR掺入法、甲苯胺兰染色分别检测细胞的增殖情况及成软骨活性。结果:与空白对照细胞相比,壳聚糖可使所培养的骨髓基质细胞表现出明显的成软骨活性。igf-1基因的参与则可显著促进细胞的增殖。结论:CS/igf-1复合物可促进对体外培养的骨髓基质细胞增殖并向成软骨细胞分化。     

盐酸四环素缓释微球对大鼠成骨细胞活性的影响

目的 观察盐酸四环素缓释微球对体外培养的成骨细胞活性的影响.方法 体外分离培养SD大鼠成骨细胞并通过形态学观察、碱性磷酸酶(ALP)钙-钴法染色鉴定其细胞生物学特征;将盐酸四环素聚乳酸-聚羟基乙酸共聚物(PLGA)微球、盐酸四环素分别与成骨细胞共培养,采用四甲基偶氮唑盐(MTT)法检测各实验组成骨细胞的增殖情况,通过碱性磷酸酶活性测定法检测各实验组成骨细胞中ALP的活性,免疫组化Ⅰ型胶原蛋白(Col Ⅰ type)染色观察各实验组成骨细胞中Ⅰ型胶原的表达情况.结果 盐酸四环素-PLGA微球能显著促进SD大鼠成骨细胞的增殖,同时增强了ALP的表达,其效应持续时间高于盐酸四环素组和空白对照组,Ⅰ型胶原在3组细胞中的表达无显著差异.结论 制备的盐酸四环素-PLGA微球具有缓释促进成骨细胞增殖和增加ALP活性的作用,在骨创伤的修复重建治疗中具有潜在的应用价值.     

体外培养的大鼠成骨细胞在钙化过程中的凋亡

目的:建立在体外培养时能保持分化表型的成骨细胞实验模型,并观察成骨细胞在体外的凋亡.方法:用酶解的方法从新生SD大鼠颅骨分离成骨细胞;用改良钙钴法及偶氮染色法测定其碱性磷酸酶(AKP)活性;用Von Kossa染色法及Fluo-3染色法检测其钙化沉积物;根据凋亡细胞中乙酰胆碱酯酶(AChE)高表达的特性,用乙酰胆碱酯酶染色法观察不同时期的凋亡细胞.结果:原代大鼠颅骨成骨细胞在体外培养44天中,逐步形成包括多层细胞结节,钙化的细胞外基质组成的骨样组织,随着基质的钙化,凋亡细胞逐步增多.结论:大鼠颅骨成骨细胞在体外发育过程的表型能反映成骨细胞在体外的成熟过程,是研究成骨细胞生物学理想的实验模型.     

BMP2/β-TCP-HA复合支架体内构建组织工程软骨的实验研究

目的 探讨以骨形态发生蛋白2(BMP2)/β磷酸三钙-透明质酸(β-TCP-HA)复合支架在裸鼠体内构建组织工程软骨的可行性.方法 分别构建BMP2/β-TCP-HA(实验组),BMP2/β-TCP(对照组)及β-TCP(空白组)支架.分离培养大鼠间质干细胞(MSCs)至三代,利用负压吸引将MSCs作为种子细胞分别接种于各组支架内,并植于裸鼠皮下.于术后12周观察其成软骨效果并对修复组织行大体,组织学及免疫组化观察.结果 术后12周实验组支架降解基本完全,能形成丰富的软骨组织,软骨细胞外基质丰富,糖胺多精(GAG)及Ⅱ型胶原免疫组化染色均旱强阳性;对照组支架大部降解,支架内形成岛状软骨增生;GAG及Ⅱ型胶原免疫组化染色呈阳性;空白组支架部分降解,以纤维组织和脂肪组织为主;仅在支架边缘见少最软骨组织,GAG及Ⅱ型胶原免疫组化染色呈阴性.结论 BMP2/β-TCP-HA复合支架为MSCs提供了一条可能有效的关节软骨修复途径,是目前软骨组织工程较为理想的细胞支架材料.     

大鼠肌源干细胞与纤维蛋白胶的细胞相容性研究

目的 观察大鼠肌源干细胞与纤维蛋白胶支架材料的细胞相容性,为肌肉组织工程选择适宜的种子细胞载体.方法 将大鼠肌源干细胞与纤维蛋白胶支架于6孔板中体外复合培养,扫描电镜下观察接种第1、7天细胞形态、黏附情况;于96孔板中分别进行2组培养:实验组(胶表面生长组)、对照组(孔板表面生长组),倒置相差显微镜下观察细胞形态与生长情况,四唑氮盐比色法检测细胞增殖率.结果 大鼠肌源干细胞能良好地在纤维蛋白胶上黏附、生长和增殖,实验组细胞倍增时间[(41.7±6.9)h]略长于对照组[ (37.2 ±4.3)h],但差异无统计学意义(P＞0.05).结论 纤维蛋白胶具有良好的细胞相容性,可作为大鼠肌源干细胞的载体.     

组织工程化胆管中管状组织细胞培养及其与支架材料的相容性

目的探讨分化胆管平滑肌细胞及内皮细胞与高分子材料聚乳酸乙醇酸共聚物(PLGA)生物相容性。方法体外培养并纯化大鼠骨髓间充质干细胞(MSCs),定向诱导分化为胆管平滑肌细胞及内皮细胞,通过形态学及PCR法加以鉴定。种子细胞与PLGA支架复合培养,测定细胞黏附率,观察细胞在支架上的生长情况。结果体外分化MSCs 4周后,细胞呈现典型树枝状胆管内皮细胞形态学改变,PCR法显示分化细胞对细胞表面标记CK19高表达;8周后,细胞呈现典型类纺锤样平滑肌细胞形态学改变,RT-PCR法显示分化细胞对细胞表面标记抗平滑肌抗体(ASMA)、平滑肌抗原22(SM22)、钙调素结合蛋白高表达。分化细胞与支架复合培养,通过测定细胞黏附率及MTT法证明细胞在支架上增殖良好,扫描电镜显示分化细胞在PLGA支架上生长良好。结论 MSCs体外经定向诱导分化具有向平滑肌细胞及内皮细胞分化能力。分化好的细胞与支架具备良好生物相容性。     

壳聚糖-明胶-磷酸三钙多孔复合体负载骨形成蛋白2用于组织工程骨的构建

目的探索壳聚糖-明胶-磷酸三钙(CS-Gel/TCP)多孔复合体作为骨形成蛋白(BMP)-2缓释载体的可行性。方法采用相分离法制备CS-Gel/TCP支架负载BMP-2复合体材料;将兔骨髓基质细胞(MSC)进行体外培养、扩增、诱导为骨髓基质成骨细胞(MSO),检测CS-Gel/TCP支架负载BMP-2复合体对细胞增殖与分化的影响。结果MSC可在CS-Gel/TCP支架上良好生长,其增殖能力不受影响,碱性磷酸酶(ALP)活性提高。结论CS-Gel/TCP多孔支架可以作为BMP-2有效的载体。     

Effective combination of aligned nanocomposite nanofibers and human unrestricted somatic stem cells for bone tissue engineering

Aim:

Bioartificial bone tissue engineering is an increasingly popular technique to solve bone defect challenges. This study aimed to investigate the interactions between matrix composition and appropriate cell type, focusing on hydroxyapatite (HA), to achieve a more effective combination for bone regeneration.

Methods:

Human unrestricted somatic stem cells (USSCs) were isolated from placental cord blood. The cellular and molecular events during the osteo-induction of USSCs were evaluated for 21 d under the following conditions: (1) in basal culture, (2) supplemented with hydroxyapatite nanoparticle (nHA) suspension, and (3) seeded on electrospun aligned nanofibrous poly-ɛ-caprolactone/poly-L-lactic acid/nHA (PCL/PLLA/nHA) scaffolds. The scaffolds were characterized using scanning electron microscope (SEM), fourier transform infrared spectroscopy (FTIR) and tensile test.

Results:

Maintenance of USSCs for 21 d in basal or osteogenic culture resulted in significant increase in osteoblast differentiation. With nHA suspension, even soluble osteo-inductive additives were ineffective, probably due to induced apoptosis of the cells. In contrast to the hindrance of proliferation by nHA suspension, the scaffolds improved cell growth. The scaffolds mimic the nanostructure of natural bone matrix with the combination of PLLA/PCL (organic phase) and HA (inorganic phase) offering a favorable surface topography, which was demonstrated to possess suitable properties for supporting USSCs. Quantitative measurement of osteogenic markers, enzymatic activity and mineralization indicated that the scaffolds did not disturb, but enhanced the osteogenic potential of USSCs. Moreover, the alignment of the fibers led to cell orientation during cell growth.

Conclusion:

The results demonstrated the synergism of PCL/PLLA/nHA nanofibrous scaffolds and USSCs in the augmentation of osteogenic differentiation. Thus, nHA grafted into PCL/PLLA scaffolds can be a suitable choice for bone tissue regeneration.     

In vitro assessment of cellular responses to rod-shaped hydroxyapatite nanoparticles of varying lengths and surface areas

Rod-shaped hydroxyapatite nanoparticles of varying dimensions (≈ 60 ± 10, 120 ± 15, 240 ± 30 nm in length, labeled respectively as nHA60, nHA120 and nHA240) with specific surface areas (47.02, 23.33, 46.12 nm(2), respectively), were synthesized and their effects on cell viability, reactive oxygen species generation and cellular interaction with BEAS-2B, RAW264.7 and HepG2 were investigated. In vitro exposure of these cell lines to rod shape nHA particles within a range of 10-300 μg/ml for 24 h did not significantly alter cell viability studied by the WST-8 assay. A significant increase in reactive oxygen species (ROS) generation was however observed with the dihydrofluorescein diacetate (DFDA) assay after 4 h incubation with these nanoparticles. The lowest level of ROS generation was observed with nHA120 (with the smallest specific surface area); whereas nHA60 and nHA240 exhibited comparable ROS generation. Subsequently, the Alizarin Red-S (ARS) assay indicated a weaker association of calcium with cells compared to nHA60 and nHA240. The results thus suggest that high surface area may increase cell-particle interaction, which in turn influenced ROS generation. The combined results from all the cell lines thus indicated high biocompatibility of rod-shaped nHA.     

In vitro assessment of cellular responses to rod-shaped hydroxyapatite nanoparticles of varying lengths and surface areas

Abstract

Rod-shaped hydroxyapatite nanoparticles of varying dimensions (≈ 60 ± 10, 120 ± 15, 240 ± 30 nm in length, labeled respectively as nHA60, nHA120 and nHA240) with specific surface areas (47.02, 23.33, 46.12 nm², respectively), were synthesized and their effects on cell viability, reactive oxygen species generation and cellular interaction with BEAS-2B, RAW264.7 and HepG2 were investigated. In vitro exposure of these cell lines to rod shape nHA particles within a range of 10–300 μg/ml for 24 h did not significantly alter cell viability studied by the WST-8 assay. A significant increase in reactive oxygen species (ROS) generation was however observed with the dihydrofluorescein diacetate (DFDA) assay after 4 h incubation with these nanoparticles. The lowest level of ROS generation was observed with nHA120 (with the smallest specific surface area); whereas nHA60 and nHA240 exhibited comparable ROS generation. Subsequently, the Alizarin Red-S (ARS) assay indicated a weaker association of calcium with cells compared to nHA60 and nHA240. The results thus suggest that high surface area may increase cell-particle interaction, which in turn influenced ROS generation. The combined results from all the cell lines thus indicated high biocompatibility of rod-shaped nHA.     

Ganoderma lucidum polysaccharides antagonize the suppression on lymphocytes induced by culture supernatants of B16F10 melanoma cells

Objectives Tumour cells produce factors such as interleukin 10 (IL‐10), transforming growth factor β1 (TGF‐β1) and vascular endothelial growth factor (VEGF) that suppress the function of immune cells or induce apoptosis of immune cells. One of the most important goals of tumour immunotherapy is to antagonize this suppression on immune cells. Ganoderma lucidum polysaccharides (Gl‐PS) may have this potential. The purpose of this study was to determine the antagonistic effects of Gl‐PS on the suppression induced by B16F10 melanoma cell culture supernatant (B16F10‐CS) on lymphocytes. Methods Gl‐PS was used on lymphocytes incubated with B16F10‐CS. Enzyme‐linked immunosorbent assay was used to determine the levels of IL‐10, TGF‐β1 and VEGF in B16F10‐CS. The MTT assay was used to determine the proliferation of lymphocytes. Immunocytochemistry and Western blot assay were used to determine perforin and granzyme B production in lymphocytes. Key findings There were elevated levels of IL‐10, TGF‐β1 and VEGF in B16F10‐CS. The lymphocyte proliferation, and perforin and granzyme B production in lymphocytes after induction with phytohemagglutinin, as well as lymphocyte proliferation in the mixed lymphocyte reaction, were suppressed by B16F10‐CS. This suppression was fully or partially antagonized by Gl‐PS. Conclusions B16F10‐CS suppressed lymphocyte proliferation and perforin and granzyme B production in lymphocytes after induction with phytohemagglutinin, as well as lymphocyte proliferation in the mixed lymphocyte reaction. This suppression may be associated with elevated levels of immunosuppressive IL‐10, TGF‐β1 and VEGF in B16F10‐CS. Gl‐PS had antagonistic effects on the immunosuppression induced by B16F10‐CS, suggesting the potential for Gl‐PS in cancer immunotherapy.     

Coordinated regulation of BACH1 and mitochondrial metabolism through tumor-targeted self-assembled nanoparticles for effective triple negative breast cancer combination therapy

The poor prognosis of triple negative breast cancer (TNBC) results from a lack of approved targeted therapies coupled with aggressive proliferation and metastasis, which is associated with high recurrence and short overall survival. Here we developed a strategy by employing tumor-targeted self-assembled nanoparticles to coordinately regulate BACH1 (BTB domain and CNC homology 1) and mitochondrial metabolism. The BACH1 inhibitor hemin and mitochondria function inhibitor berberine derivative (BD) were used to prepare nanoparticles (BH NPs) followed by the modification of chondroitin sulfate (CS) on the surface of BH NPs to achieve tumor targeting (CS/BH NPs). CS/BH NPs were found to be able to inhibit tumor migration and invasion by significantly decreasing the amounts of tumor cell metabolites, glycolysis and metastasis-associated proteins, which were related to the inhibition of BACH1 function. Meanwhile, decreased mitochondrial membrane potential, activated caspase 3/9 and increased ROS production demonstrated coordinated regulation of BACH1 and mitochondrial metabolism. In a xenograft mice model of breast cancer, CS/BH NPs significantly inhibited tumor growth and metastasis due to the synergetic effect of hemin and BD without showing obvious toxicities for major organs. In sum, the results of efficacy and safety experiments suggest potential clinical significance of the prepared self-assembled CS/BH nanoparticles for the treatment of TNBC.     

Cytotoxicity of hydroxyapatite nanoparticles is shape and cell dependent

Nanosized hydroxyapatite (nHA) has been proposed as drug delivery vehicles because of its biocompatibility. While the possible risks of nHA inducing inflammation have been highlighted, the specific influence of varying nHA particle morphology is still unclear. In order to establish this understanding, nHA of four different shapes—needle (nHA-ND), plate (nHA-PL), sphere (nHA-SP) and rod (nHA-RD)—were synthesized. The particle effects with the concentration of 10–300 μg/mL on cytotoxicity, oxygen species generation, production of inflammatory cytokines (TNF-α and IL-6), particle–cell association and cellular uptake were evaluated on BEAS-2B and RAW264.7 cells. Results show that nHA-ND and nHA-PL induced the most significant cell death in BEAS-2B cultures compared to nHA-SP and nHA-RD. Necrosis–apoptosis assay by FITC Annexin V and propidium iodide (PI) staining revealed loss of the majority of BEAS-2B by necrosis. No significant cell death was recorded in RAW264.7 cultures exposed to any of the nHA groups. Correspondingly, no significant differences were observed in TNF-α level for RAW264.7 cells upon incubation with nHA of different shapes. In addition, nHA-RD exhibited a higher degree of particle–cell association and internalization in both BEAS-2B and RAW264.7 cells, compared to nHA-ND. The phenomena suggested that higher particle–cell association and increased cellular uptake of nHA need not result in increased cytotoxicity, indicating the importance of particle shape on cytotoxicity. Specifically, needle- and plate-shaped nHA induced the most significant cell-specific cytotoxicity and IL-6 expression but showed the least particle–cell association. Taken collectively, we demonstrated the shape-dependent effects of nHA on cytotoxicity, inflammatory cytokine expression and particle–cell association.     

Hyaluronic acid/Chitosan nanoparticles as delivery vehicles for VEGF and PDGF-BB

The development of a vascular network in tissue-engineered constructs is a fundamental bottleneck of bioregenerative medicine, particularly when the size of the implant exceeds a certain limit given by diffusion lengths and/or if the host tissue shows a very active metabolism. One of the approaches to achieve the vascularization of tissue constructs is generating a sustained release of proangiogenic factors from the ischemic site. This work describes the formation and characterization of hyaluronic acid-chitosan (HA/CS) nanoparticles for the delivery of two pro-angiogenic growth factors: vascular endothelial growth factor (VEGF) and platelet derived growth factor (PDGF-BB). These nanoparticles were prepared by an ionic gelification technique, and different formulations were developed by encapsulating the growth factors in association with two stabilizing agents: bovine serum albumin or heparin sodium salt. These carriers were characterized with regard to their physicochemical properties, their stability in biological media, and their cytotoxicity in the C3a hepatoma cell line. The results show that nanoparticles around 200?nm can be prepared by this method. HA/CS nanoparticles were stable when incubated in EMEM cell culture medium or in water at 37°C for 24?h. Cell culture tests confirmed that HA/CS nanoparticles are not cytotoxic within the concentration range used for growth factor delivery. Moreover, HA/CS nanoparticles were able to entrap efficiently both growth factors, reaching association values of 94% and 54% for VEGF and PDGF, respectively. In vitro release studies confirm that PDGF-BB is released from HA/CS nanoparticles in a sustained manner over ～ 1 week. On the other hand, VEGF is completely released within the first 24?h.     

Hyaluronic acid/Chitosan nanoparticles as delivery vehicles for VEGF and PDGF-BB

The development of a vascular network in tissue-engineered constructs is a fundamental bottleneck of bioregenerative medicine, particularly when the size of the implant exceeds a certain limit given by diffusion lengths and/or if the host tissue shows a very active metabolism. One of the approaches to achieve the vascularization of tissue constructs is generating a sustained release of proangiogenic factors from the ischemic site. This work describes the formation and characterization of hyaluronic acid-chitosan (HA/CS) nanoparticles for the delivery of two pro-angiogenic growth factors: vascular endothelial growth factor (VEGF) and platelet derived growth factor (PDGF-BB). These nanoparticles were prepared by an ionic gelification technique, and different formulations were developed by encapsulating the growth factors in association with two stabilizing agents: bovine serum albumin or heparin sodium salt. These carriers were characterized with regard to their physicochemical properties, their stability in biological media, and their cytotoxicity in the C3a hepatoma cell line. The results show that nanoparticles around 200?nm can be prepared by this method. HA/CS nanoparticles were stable when incubated in EMEM cell culture medium or in water at 37°C for 24?h. Cell culture tests confirmed that HA/CS nanoparticles are not cytotoxic within the concentration range used for growth factor delivery. Moreover, HA/CS nanoparticles were able to entrap efficiently both growth factors, reaching association values of 94% and 54% for VEGF and PDGF, respectively. In vitro release studies confirm that PDGF-BB is released from HA/CS nanoparticles in a sustained manner over approximately 1 week. On the other hand, VEGF is completely released within the first 24?h.     

Free radical scavenging and apoptotic effects of Cordyceps sinensis fractionated by supercritical carbon dioxide.

Supercritical carbon dioxide (SC-CO2) was used as the elution solvent for fractioning ethanolic extract (E) of Cordyceps sinensis (CS), a traditional Chinese herbal remedy, into R, F1, F2, and F3 fractions. This extractive fractionation method is amenable to large scale and is nontoxic. These four fractions were characterized in terms of total polysaccharides and cordycepin concentrations, scavenging ability of free radicals, and anti-tumor activities. Experimental results demonstrated that fractionation altered the distributions of total polysaccharides and cordycepin in fractions. Fraction R was the most active fraction to scavenge free radicals and inhibit the proliferation of carcinoma cells, followed by the fraction F1 and the extract E. The effect of scavenging on 1,1-diphenyl-2-picryl hydrazyl (DPPH) of CS extract and fractions at 2 mg/ml was R (93%), F1 (75%), E (66%), F2 (47%), and F3 (27%). The IC50 (50% cell growth inhibitory concentration) of tumor cell proliferation and colony formation on human colorectal (HT-29 and HCT 116) and hepatocellular (Hep 3B and Hep G2) carcinoma cells by fraction R were around 2 microg/ml. Conversely, R did not affect the growth of normal dividing human peripheral blood mononuclear cells (PBMC) by exhibiting a large value of IC50 over 200 microg/ml. Accumulation of tumor cells at sub-G1 phase and the fragmentation of DNA, typical features of programmed cell death, were observed in a time and dose dependent manner. Scavenging of free radicals and anti-cancer activity (value of IC50) correlated closely with the quantities of polysaccharides (Spearman's rho=0.901 and -0.870, respectively). Taken together, our findings suggest that fraction R, obtained by SC-CO2 fluid extractive fractionation, showed strong scavenging ability and selectively inhibited the growth of colorectal and hepatocellular cancer cells by the process of apoptosis.