成人骨髓成骨细胞体外培养

目的　研究成人骨髓基质干细胞在体外培养条件下的成骨能力及生物学特性 ,探讨简便易行的成人成骨细胞体外培养方法 ,为骨组织工程选择理想的种子细胞来源。方法　因诊断需要抽取健康成人骨髓组织 ,在含体积分数为 10 %胎牛血清的DMEM培养基中 ,置于 37℃、含体积分数为 5 %的CO2 湿化空气孵箱中培养 ,传代后改用含地塞米松、β-甘油磷酸钠和维生素C的条件培养基培养 ,用倒置相差显微镜观察、HE染色、扫描与透射电镜观察增殖和分化情况 ,并测定培养细胞的生长曲线 (MTT法 )、碱性磷酸酶活性和钙结节形成能力。结果　采用本法在体外培养的成人成骨细胞生长良好 ,生化指标稳定 ,表现出与典型的成骨细胞相似的形态特征和生物学特性。结论　本实验方法取材方便 ,所培养的细胞具有成骨细胞的特性 ,可作为骨组织工程种子细胞培养的常规方法     

Association of COLIA1 Sp1 Alleles with Defective Bone Nodule Formation In Vitro and Abnormal Bone Mineralization In Vivo

Previous work identified a G/T polymorphism affecting a Sp1 binding site in a regulatory region of the COLIA1 gene that predisposes to osteoporotic fractures by affecting bone strength through mechanisms that are partly independent of differences in bone mineral density (BMD). To clarify the mechanisms by which COLIA1 Sp1 alleles influence bone strength we used quantitative backscattered electron imaging (qBEI) to characterize bone mineralization in biopsy samples from subjects of different COLIA1 genotype and studied the ability of osteoblast-like cells cultured from subjects of different genotypes to form mineralized bone nodules. The qBEI analysis showed a significant (P = 0.014) reduction in mineralization in bone biopsies from G/T heterozygotes (n = 6) compared with G/G homozygotes (n = 7) and a significant increase in heterogeneity of mineralization (P = 0.017). The in vitro studies showed that osteoblasts derived from G/T heterozygotes (n = 5) were significantly less able to produce mineralized bone nodules than G/G homozygotes (n = 10) at all time-points examined (P < 0.0001). We conclude that carriage of the COLIA1 Sp1 “T” allele is associated with an impaired ability of osteoblast-like cells to form mineralized bone nodules in vitro and with abnormalities of bone mineralization in vivo. This suggests that the increased bone fragility in carriers of the COLIA1 Sp1 allele may result in part from defects in bone mineralization. T.L.S. and P.R. contributed equally.     

Increase in the Potential of Osteoblasts to Support Bone Resorption by Osteoclasts In Vitro in Response to Roughness of Bone Surface

The development of the potential of osteoblasts to support bone resorption by osteoclasts in response to roughness on bone slices was examined in the co-incubation cell system of immature osteoclasts and osteoblastic cells. The immature osteoclasts, which need alkaline phospatase (ALP)-positive osteoblastic cells for bone resorption, were generated in mouse spleen cultures with 1, 25-dihydroxyvitamin D₃ and prostaglandin E₂. ALP-negative osteoblastic cells from mouse calvaria were incubated on rough surfaced bone slices for 3 days. The number of ALP-positive cells increased greatly on the rough surface, but little on the smooth surface. When immature osteoclasts were added and incubated for 1 more day, the resorption pit number and the total pit areas on the smooth surface were not much different from those before incubation but were approximately four times higher on the rough surface. Received: 21 July 1998 / Accepted: 12 March 1999     

Response of Human Osteoblasts to Polymethylmetacrylate In Vitro

The effects of a polymethylmetacrylate (PMMA) powder with a diameter between 0.5 and 25 μm have been studied in vitro on several human osteoblast populations obtained from different sources. Parameters of cell activity such as cell growth, collagen synthesis, osteocalcin, and interleukin-6 (IL-6) production have been evaluated. Cell proliferation and collagen synthesis were inhibited after exposure to bone cement, whereas osteocalcin and IL-6 production were stimulated. These results suggest that PMMA particles could affect osteoblast activity in a way that could contribute, together with other factors, to periprosthetic osteolysis through two different pathways: a reduced periprosthetic bone formation due to the reduced osteoblast proliferation and collagen synthesis, and an osteoblast-mediated activation of osteoclastic bone resorption as suggested by the increased osteocalcin and IL-6 synthesis. In fact, osteocalcin has been demonstrated to have a role in osteoclast recruitment to bone surfaces, and IL-6 is known to induce osteoclastogenesis and to directly stimulate bone resorption. Received: 20 December 1996 / Accepted: 2 July 1997     

Pterostilbene Inhibits Pancreatic Cancer In Vitro

Introduction  

Stilbenes are phenolic compounds present in grapes and blueberries. Resveratrol, a naturally occurring compound present in grapes, has been shown to have potent antioxidant properties as well as an ability to induce apoptosis. Resveratrol has also been reported to have significant inhibitory effects against a variety of primary tumors including breast, colon, and prostate. Pterostilbene, a naturally occurring analogue of resveratrol found in blueberries, also has antioxidant and antiproliferative properties. It is also substantially more bioavailable orally than resveratrol. These effects have not been studied in pancreatic cancer. We hypothesized that pterostilbene would inhibit pancreatic cancer cell growth in vitro.     

Aminobisphosphonates Cause Osteoblast Apoptosis and Inhibit Bone Nodule Formation In Vitro

Bisphosphonates are widely used for the treatment of bone diseases associated with increased osteoclastic bone resorption. Bisphosphonates are known to inhibit biochemical markers of bone formation in vivo, but it is unclear to what extent this is a consequence of osteoclast inhibition or a direct inhibitory effect on cells of the osteoblast lineage. In order to investigate this issue, we studied the effects of various bisphosphonates on osteoblast growth and differentiation in vitro. The aminobisphosphonates pamidronate and alendronate inhibited osteoblast growth, caused osteoblast apoptosis, and inhibited protein prenylation in osteoblasts in a dose-dependent manner over the concentration range 20-100 microM. Further studies showed that alendronate in a dose of 0.1 mg/kg inhibited protein prenylation in calvarial osteoblasts in vivo, indicating that alendronate can be taken up by osteoblasts in sufficient amounts to inhibit protein prenylation at clinically relevant doses. Pamidronate and alendronate inhibited bone nodule formation at concentrations 10-fold lower than those required to inhibit osteoblast growth. These effects were not observed with non-nitrogen-containing bisphosphonates or with other inhibitors of protein prenylation and were only partially reversed by cotreatment with a fourfold molar excess of ss-glycerol phosphate. We conclude that aminobisphosphonates cause osteoblast apoptosis in vitro at micromolar concentrations and inhibit osteoblast differentiation at nanomolar concentrations by mechanisms that are independent of effects on protein prenylation and may be due in part to inhibition of mineralization. While these results need to be interpreted with caution because of uncertainty about the concentrations of bisphosphonates that osteoblasts are exposed to in vivo, our studies clearly demonstrate that bisphosphonates exert strong inhibitory effects on cells of the osteoblast lineage at similar concentrations to those that cause osteoclast inhibition. This raises the possibility that inhibition of bone formation by bisphosphonates may be due in part to a direct inhibitory effect on cells of the osteoblast lineage.     

皮质骨和其他不同来源兔成骨细胞的体外培养和生物学特性比较

目的通过比较皮质骨和其他不同来源兔成骨细胞的体外培养和部分成骨功能,鉴定并探讨不同来源成骨细胞的增殖、成骨能力及其培养方法。方法取材于3个月龄新西兰大白兔,分别用组织块法和酶消化法分离培养尺骨皮质、髂骨、胫骨骨膜来源的细胞,取髂骨骨髓用密度梯度离心法分离提取干细胞,将细胞分为皮质骨组、骨膜组、松质骨组、干细胞诱导组和干细胞常规组。取第3代细胞进行实验,倒置相差显微镜下观察和结晶紫染色比较细胞形态、MTT法测定细胞增殖曲线、对硝基酚法测碱性磷酸酶(ALP)活性、酶免法测定骨钙素(BGP)活性等。结果普通显微镜下不同来源细胞在形态学上无显著差异;增殖和成骨能力:骨膜组和干细胞常规组增殖最快,皮质骨组和松质骨组居中,干细胞诱导组增殖最慢;干细胞常规组无明显ALP、BGP表达,不同来源细胞的ALP、BGP表达情况大致呈如下关系:骨膜组皮质骨组松质骨组干细胞诱导组。结论皮质骨、骨膜、松质骨、骨髓干细胞均可以培养出成骨细胞,皮质骨来源的成骨细胞成分相对单纯,生命力较旺盛;骨膜细胞在增殖和成骨能力方面有一定优势,但细胞成分相对不纯。     

鼠骨组织成骨细胞的离体培养和生长特性

目的：观察大鼠骨组织来源成骨细胞的体外分离培养的条件及生长特征，为骨组织工程学实验研究奠定基础。方法；取出生24hSD乳鼠的顶骨，酶经法分离培养成骨细胞并传代，观察其生物学特征，并进行ALP活性测定，绘制生长曲线、分裂指数曲线和贴壁率曲线、测定细胞贴壁及延展时间。并将培养细胞进行冻存、复苏、比较细胞特性有无改变。结果：培养细胞在第8代以前生长性状稳定，具有典型的成骨细胞特性，可作为实验细胞；第4d为细胞生长倍增时间，第5－6d细胞达生长高峰；第4d细胞分裂最为旺盛，达18％；传代后10h贴壁率最高，为90％；冻存复苏后的细胞生物学特性无改变。结论：本实验方法体外培养的成骨细胞，生长性状稳定，增殖速度快，具有与体内成骨细胞相同的生物学特性，保证了相关实验的可靠性和准确性，可作为骨组织工程学研究的种子细胞。     

Botulinum Toxin-induced Muscle Paralysis Inhibits Heterotopic Bone Formation

Background

Short-term muscle atrophy induced by botulinum toxin A (BTxA) has been observed to impair osteogenesis in a rat closed femur fracture model. However, it is unclear whether the underlying mechanism is a direct effect of BTxA on muscle-bone interactions or an indirect effect that is driven by skeletal unloading. Because skeletal trauma in the closed fracture model also leads to disuse atrophy, we sought to mitigate this confounding variable by examining BTxA effects on muscle-bone interactions in two complementary in vivo models in which osteogenesis is induced in the absence of skeletal unloading. The overall aim of this study was to identify a potential strategy to inhibit pathological bone formation and heterotopic ossification (HO).

Questions/purposes

(1) Does muscle paralysis inhibit periosteal osteogenesis induced by a transcortical defect? (2) Does muscle paralysis inhibit heterotopic bone formation stimulated by intramuscular bone morphogenetic protein (BMP) injection?

Methods

Focal osteogenesis was induced in the right hindlimb of mice through surgical initiation of a small transcortical defect in the tibia (fracture callus; n = 7/group) or intramuscular injection of BMP-2 (HO lesion; n = 6/group), both in the presence/absence of adjacent calf paralysis. High-resolution micro-CT images were obtained in all experimental groups 21 days postinduction and total volume (ie, perimeter of periosteal callus or HO lesion) and bone volume (calcified tissue within the total volume) were quantified as primary outcome measures. Finally, these outcome measures were compared to determine the effect of muscle paralysis on inhibition of local osteogenesis in both studies.

Results

After a transcortical defect, BTxA-treated mice showed profound inhibition of osteogenesis in the periosteal fracture callus 21 days postsurgery compared with saline-treated mice (total volume: 0.08 ± 0.06 versus 0.42 ± 0.11 mm³, p < 0.001; bone volume: 0.07 ± 0.05 versus 0.32 ± 0.07 mm³, p < 0.001). Similarly, BMP-2-induced HO formation was inhibited by adjacent muscle paralysis at the same time point (total volume: 1.42 ± 0.31 versus 3.42 ± 2.11 mm³, p = 0.034; bone volume: 0.68 ± 0.18 versus 1.36 ± 0.79 mm³, p = 0.045).

Conclusions

Our data indicate that BTxA-induced neuromuscular inhibition mitigated osteogenesis associated with both a transcortical defect and BMP-2-induced HO.

Clinical Relevance

Focal neuromuscular inhibition represents a promising new approach that may lead to a new clinical intervention to mitigate trauma-induced HO, a healthcare challenge that is severely debilitating for civilian and war-wounded populations, is costly to both the patient and the healthcare system, and currently lacks effective treatments.     

Thyroid Releasing Hormone Inhibits Testosterone Metabolism by Rat Prostate In Vitro

A method involving thin layer chromatography (TLC) was developed to assess 5 alpha-DHT-reductase activity in rat ventral prostate, in terms of the amount of testosterone metabolised to its main 5 alpha-reduced compound, dihydrotestosterone (DHT). Using this method an in vitro study was carried out to determine 5 alpha-DHT reductase activity in the rat ventral prostate as modulated by thyroid releasing hormone (TRH). The study revealed a decrease in the enzyme activity with increasing doses of TRH, as shown by a decrease in the extent of reduction of testosterone to DHT. The ratios of the counts for DHT and testosterone however did not show any dose related effect.     

Taurolidine Inhibits Tumor Cell Growth In Vitro and In Vivo

Background: Taurolidine, a derivative of the amino acid taurine, exhibits antiendotoxin, antibacterial, and antiadherence activity. We hypothesized that Taurolidine may inhibit tumor cell growth, both in an in vitro and in vivo setting. Our aim was to examine the effect of Taurolidine on the growth of a rat metastatic colorectal tumor cell line (DHD/K12/TRb) in vitro and in vivo.Methods: In the in vitro experiments, DHD/K12/TRb cells were incubated with 5, 10, 15, 25 g/ml of Taurolidine. Cells incubated in culture medium alone were used as controls. Cell proliferation, cell viability, cell death, and cell apoptosis were measured using commercially available techniques. In the in vivo experiment, BD IX rats were randomized into two groups (n = 10/group). Group A (control) underwent laparotomy and instillation of DHD/K12/TRb tumor cells intraperitoneally followed by phosphate buffered saline (PBS). Group B received Taurolidine (100 mg/kg) instead of PBS. Animals were killed after 24 days and tumor burden assessed by counting the number of tumor nodules in the peritoneal cavity.Results: Incubation of the tumor cells with Taurolidine resulted in a 4-fold decrease in proliferation rates (25 ± 4% vs. 100 ± 28% for controls) and a 4-fold increase in cell necrosis as demonstrated by the increase in LDH release (403 ± 28% vs. 100 ± 26% for controls), at a Taurolidine concentration of 25 g/ml. A dose-dependent decrease in cell viability was also observed. In the in vivo study, local Taurolidine administration resulted in significant decreases in tumor burden (3 ± 1 nodules in Group B animals vs. 649 ± 101 nodules in Group A animals).Conclusions: Taurolidine inhibits the growth of a rat metastatic colorectal tumor cell line in vitro and in vivo and thus may have potential in the prevention of peritoneal metastases.     

新型双相陶瓷材料复合成骨细胞构建人工骨及其体内成骨的观察

目的 观察骨髓来源的成骨细胞与新型双相陶瓷材料复合培养后细胞生长状况及其体内异位成骨能力。方法 将来源于兔骨髓的成骨细胞与新法制备的HA/TCP共培养2周,通过相差显微镜、扫描电镜观察体外细胞生长情况;然后将复合物自体异位植入体内,6周后观察体内成骨情况。结果 扫描电镜显示材料表面和孔隙内均有成骨细胞生长,有良好增殖活动性和稳定细胞表型,材料中心区未见细胞生长;植入体内6周后取材见内植物有新骨形成、多位于内植物表面,可见成骨细胞、骨细胞、髓腔样结构、板层样骨基质等正常骨组织结构。结论 新型双相陶瓷支架可用作组织工程骨的细胞外基质材料,骨髓来源的成骨细胞可用作骨组织工程的种子细胞。     

Overexpression of BCLXL in Osteoblasts Inhibits Osteoblast Apoptosis and Increases Bone Volume and Strength

The Bcl2 family proteins, Bcl2 and BclXL, suppress apoptosis by preventing the release of caspase activators from mitochondria through the inhibition of Bax subfamily proteins. We reported that BCL2 overexpression in osteoblasts using the 2.3 kb Col1a1 promoter increased osteoblast proliferation, failed to reduce osteoblast apoptosis, inhibited osteoblast maturation, and reduced the number of osteocyte processes, leading to massive osteocyte death. We generated BCLXL (BCL2L1) transgenic mice using the same promoter to investigate BCLXL functions in bone development and maintenance. Bone mineral density in the trabecular bone of femurs was increased, whereas that in the cortical bone was similar to that in wild‐type mice. Osteocyte process formation was unaffected and bone structures were similar to those in wild‐type mice. A micro‐CT analysis showed that trabecular bone volume in femurs and vertebrae and the cortical thickness of femurs were increased. A dynamic bone histomorphometric analysis revealed that the mineralizing surface was larger in trabecular bone, and the bone‐formation rate was increased in cortical bone. Serum osteocalcin but not TRAP5b was increased, BrdU‐positive osteoblastic cell numbers were increased, TUNEL‐positive osteoblastic cell numbers were reduced, and osteoblast marker gene expression was enhanced in BCLXL transgenic mice. The three‐point bending test indicated that femurs were stronger in BCLXL transgenic mice than in wild‐type mice. The frequency of TUNEL‐positive primary osteoblasts was lower in BCLXL transgenic mice than in wild‐type mice during cultivation, and osteoblast differentiation was enhanced but depended on cell density, indicating that enhanced differentiation was mainly owing to reduced apoptosis. Increased trabecular and cortical bone volumes were maintained during aging in male and female mice. These results indicate that BCLXL overexpression in osteoblasts increased the trabecular and cortical bone volumes with normal structures and maintained them majorly by preventing osteoblast apoptosis, implicating BCLXL as a therapeutic target of osteoporosis. © 2016 American Society for Bone and Mineral Research.     

Sustained BMP Signaling in Osteoblasts Stimulates Bone Formation by Promoting Angiogenesis and Osteoblast Differentiation

Angiogenesis and bone formation are tightly coupled during the formation of the skeleton. Bone morphogenetic protein (BMP) signaling is required for both bone development and angiogenesis. We recently identified endosome‐associated FYVE‐domain protein (endofin) as a Smad anchor for BMP receptor activation. Endofin contains a protein‐phosphatase pp1c binding domain, which negatively modulates BMP signals through dephosphorylation of the BMP type I receptor. A single point mutation of endofin (F872A) disrupts interaction between the catalytic subunit pp1c and sensitizes BMP signaling in vitro. To study the functional impact of this mutation in vivo, we targeted expression of an endofin (F872A) transgene to osteoblasts. Mice expressing this mutant transgene had increased levels of phosphorylated Smad1 in osteoblasts and showed increased bone formation. Trabecular bone volume was significantly increased in the transgenic mice compared with the wildtype littermates with corresponding increases in trabecular bone thickness and number. Interestingly, the transgenic mice also had a pronounced increase in the density of the bone vasculature measured using contrast‐enhanced μCT imaging of Microfil‐perfused bones. The vessel surface and volume were both increased in association with elevated levels of vascular endothelial growth factor (VEGF) in osteoblasts. Endothelial sprouting from the endofin (F872A) mutant embryonic metatarsals cultured ex vivo was increased compared with controls and was abolished by an addition of a VEGF neutralizing antibody. In conclusion, osteoblast targeted expression of a mutant endofin protein lacking the pp1c binding activity results in sustained signaling of the BMP type I receptor, which increases bone formation and skeletal angiogenesis.     

CRMP4 Inhibits Bone Formation by Negatively Regulating BMP and RhoA Signaling

We identified the neuroprotein collapsing response mediator protein‐4 (CRMP4) as a noncanonical osteogenic factor that regulates the differentiation of mouse bone marrow skeletal stem cells (bone marrow stromal stem cells [mBMSCs]) into osteoblastic cells. CRMP4 is the only member of the CRMP1–CRMP5 family to be expressed by mBMSCs and in osteoprogenitors of both adult mouse and human bones. In vitro gain‐of‐function and loss‐of‐function of CRMP4 in murine stromal cells revealed its inhibitory effect on osteoblast differentiation. In addition, Crmp4‐deficient mice (Crmp4^–/–) displayed a 40% increase in bone mass, increased mineral apposition rate, and bone formation rate, compared to wild‐type controls. Increased bone mass in Crmp4^–/– mice was associated with enhanced BMP2 signaling and BMP2‐induced osteoblast differentiation in Crmp4^–/– osteoblasts (OBs). Furthermore, Crmp4^–/– OBs exhibited enhanced activation of RhoA/focal adhesion kinase (FAK) signaling that led to cytoskeletal changes with increased cell spreading. In addition, Crmp4^–/– OBs exhibited increased cell proliferation that was mediated via inhibiting cyclin‐dependent kinase inhibitor 1B, p27^Kip1 and upregulating cyclin D1 expression which are targets of RhoA signaling pathway. Our findings identify CRMP4 as a novel negative regulator of osteoblast differentiation. © 2016 American Society for Bone and Mineral Research.     

Species Differences in Growth Requirements for Bone Marrow Stromal Fibroblast Colony Formation In Vitro

The marrow stromal fibroblast (MSF) population has been shown to include precursor cells for at least five types of connective tissue: bone, cartilage, adipose tissue, fibrous tissue, and hematopoiesis-supporting reticular stroma. In this study, growth requirements for MSF colony formation were studied in vitro. In order to exclude the influence of nonadherent cells, after a period of initial adhesion of bone marrow cells in serum-containing medium nonadherent cells were removed. Further cultivation was carried out in either serum-containing or serum-free conditions, with or without feeder cells (irradiated bone marrow cells). This approach revealed differences between animal species in initial MSF growth requirements. In serum-containing conditions, mouse MSF precursor cells (colony-forming units-fibroblast, CFU-Fs) were shown to be feeder cell dependent: MSF colonies were formed only in the presence of feeder cells. Guinea pig CFU-Fs were partially feeder cell dependent, whereas human CFU-Fs were feeder cell independent. In serum-free conditions, CFU-Fs of all three species were feeder cell dependent. The difference between the growth requirements for mouse and human MSFs was not caused by serum origin or concentration, feeder cell origin, or differences in the preparation of marrow cell suspensions. Received: 9 November 1995 / Accepted: 8 March 1996     

Tetracyclines Inhibit Rat Osteoclast Formation and Activity In Vitro and Affect Bone Turnover in Young Rats In Vivo

An experiment was designed to investigate whether systemic administration of tetracyclines (TCs) as bone fluorochrome labels could interfere with bone modeling in vivo and inhibit osteoclast formation and activity in vitro. Cell cultures of rat bone marrow macrophages revealed that TC and oxytetracycline inhibited osteoclastogenesis and bone resorption and stimulated apoptosis. Forty rats in five groups were treated with saline, calcein green, alizarin red S, TC, or oxytetracycline. Their tibias were used for histomorphometric analysis, including bone static, dynamic, and resorption parameters in the tibial proximal metaphysis. No significant differences in bone volume per tissue volume, trabecular number, trabecular thickness, trabecular separation, bone formation rate per bone surface, mineralizing surface, or mineral apposition rate were observed. TC or oxytetracycline decreased eroded surface, number of osteoclasts per bone perimeter, and osteoclast surface per bone surface by about 50%. The results demonstrated that TC and oxytetracycline inhibit rat osteoclast formation and activity in vitro, and histomorphometric parameters involved in bone turnover may be affected by the use of oxytetracycline and TC as fluorescent bone labels in vivo.     

Mechanism by which MLO-A5 Late Osteoblasts/Early Osteocytes Mineralize in Culture: Similarities with Mineralization of Lamellar Bone

The mechanisms whereby bone mineralizes are unclear. To study this process, we used a cell line, MLO-A5, which has highly elevated expression of markers of the late osteoblast such as alkaline phosphatase, bone sialoprotein, parathyroid hormone type 1 receptor, and osteocalcin and will mineralize in sheets, not nodules. In culture, markers of osteocytes and dendricity increase with time, features of differentiation from a late osteoblast to an early osteocyte. Mineral formation was examined using transmission electron microscopy, scanning electron microscopy with energy-dispersive X-ray analysis, and atomic force microscopy. At 3–4 days of culture, spheres of approximately 20–50 nm containing calcium and phosphorus were observed budding from and associated with developing cellular projections. By 5–6 days, these calcified spheres were associated with collagen fibrils, where over time they continued to enlarge and to engulf the collagen network. Coalescence of these mineralized spheres and collagen-mediated mineralization were responsible for the mineralization of the matrix. Similar calcified spheres were observed in cultured fetal rat calvarial cells and in murine lamellar bone. We propose that osteoid-osteocytes generate spherical structures that calcify during the budding process and are fully mineralized on their developing cellular processes. As the cellular process narrows in diameter, these mineralized structures become associated with and initiate collagen-mediated mineralization.