Establishment of a bipotent cell line CL-1 which differentiates into chondrocytes and adipocytes from adult mouse

OBJECTIVE: Establishment of a clonal bipotent chondroprogenitor cell line from adult mouse to provide a new tool for the elucidation of chondrogenesis in adult animal. DESIGN: A clonal cell line CL-1 was established from tibia of adult mouse. Differentiation of CL-1 was characterized in monolayer culture. Effects of growth factors (TGF-beta(1), IGF-I, bFGF) and hormones (all trans retinoic acid, 1 alpha.25(OH)(2)D(3), PTH (1-34)) on the growth and differentiation of CL-1 were examined. Bipotency of CL-1 in vivo was examined by transplantation into SCID mice. RESULTS: CL-1 formed alcian blue (pH1.0) positive nodules spontaneously. The nodules were mineralized in the presence of ascorbic acid and beta-glycerophosphate. CL-1 differentiated also into oil red O positive adipocytes spontaneously. CL-1 cells expressed specific genes of chondrocytes (collagen type II, X, aggrecan) and adipocytes (PPAR-gamma(2), aP(2)). Hyaline cartilage and adipose tissue formation was observed also in subcutaneously transplanted CL-1 cells into SCID mice. These data demonstrate that CL-1 has bipotency either in vitro or in vivo. TGF-beta(1)suppressed growth of CL-1 and induced dominant chondrogenesis accompanied with marked suppression of adipogenesis in 10% FCS. IGF-I stimulated both growth (in 3% FCS) and differentiation of CL-1 into both lineages (in 10% FCS). 1 alpha.25(OH)(2)D(3)and all trans retinoic acid acted as negative regulators on proliferation and differentiation of CL-1 in 10% FCS. CONCLUSIONS: CL-1 will be a useful tool for the understanding of chondrogenesis in adult animal. Furthermore, CL-1 can be also a powerful tool for screening of the chondrogenic agent.     

Isolation and characterization of a mesenchymal cell line that differentiates into osteoblasts in response to BMP-2 from calvariae of GFP transgenic mice

We established the clonal mesenchymal cell line, GFP-C3 (C3), which differentiates into osteoblasts in response to BMP-2 from calvariae of newborn green fluorescence protein (GFP) transgenic mice. This cell line cultured with control medium expressed low levels of alkaline phosphatase (ALP) activity and osterix mRNA and undetectable ALP and osteocalcin mRNA. Incubation of these cells with rhBMP-2 increased ALP activity dose-dependently and induced substantial levels of ALP, osteocalcin and osterix mRNA expression. C3 cells infected with adenovirus vector encoding BMP-2 (AdBMP-2) or Runx2 (AdRunx2) showed greatly increased ALP mRNA expression in a time-dependent fashion. Transduction with AdRunx2-induced expression of ALP and osteocalcin mRNA, but not osterix mRNA by day 3. Transduction with AdBMP-2 induced apparent expression of ALP and osterix mRNA by day 1 after transduction, but induced only weak expression of osteocalcin mRNA day 3 after transduction. Transplantation of C3 cells transduced with AdBMP-2 into back subfascia in wild-type mice with a complex of poly-d,l-lactic-co-glycolic acid/gelatin sponge (PGS) generated ectopic bone formation involving GFP-positive osteoblasts and osteocytes 2 weeks after transplantation. C3 cells transduced with AdRunx2 or AdLacZ failed to induce ectopic bone formation. Transplantation of C3 cells transduced with AdBMP-2 into craniotomy defects in wild-type mice using PGS as a carrier induced bone formation 2 weeks after transplantation, and replaced defects 4 weeks after transplantation. C3 cells transduced with AdRunx2 failed to induce bone repair after transplantation into craniotomy defects. These results indicate that C3 cells retain differentiation potential into osteoblasts in response to BMP-2. They are useful tools for analyzing the process of osteoblast differentiation in vivo after transplantation.     

大鼠骨髓基质细胞体外成脂、成骨分化的研究

目的　观察体外定向诱导大鼠骨髓基质细胞分化为脂肪细胞和成骨细胞。方法　全骨髓法分离大鼠骨髓基质细胞 ,传 3代后分别在成脂、成骨诱导条件下继续培养 ,油红O染色、碱性磷酸酶染色和VonKossa染色判定其分化结果。结果　传 3代大鼠骨髓基质细胞成脂诱导 2 1d后 ,分化为脂肪细胞的阳性率为 (83. 6± 2 . 8) % ,成骨诱导 12d后碱性磷酸酶染色阳性率达 (87. 6± 2. 8) % ,连续诱导35d可见矿化结节形成。结论　随着诱导条件的不同 ,大鼠骨髓基质细胞在体外可定向分化为脂肪细胞或成骨细胞。     

特异性阻抑DKK-1对小鼠脂肪细胞向成骨细胞转分化的影响研究

[目的]研究特异性阻抑Wnt信号通路抑制因子DKK-1对脂肪细胞向成骨细胞的转分化的影响,以进一步探讨激素性股骨头坏死的发病机制及其防治。[方法]将小鼠前脂肪细胞3T3～L1诱导分化为脂肪细胞,将分化成功的脂肪细胞分为两组:对照组在DMEM(H)培养基培养,实验组在DMEM(H)+DKK-1抗体培养基培养。两组细胞培养3周后分别行油红O染色、ALP染色及茜素红钙结节染色;RT-PCR检测PPARγ-2、LPL、ALP、OCN及Runx-2基因mRNA的转录水平;Western-blot检测PPARγ-2、Runx-2的蛋白表达水平。[结果]与对照组相比,加入DKK-1抗体的实验组的细胞形态呈长梭形,胞浆内未见脂滴沉积,有成骨活性表达,有钙结节形成;RT-PCR结果显示实验组成骨因子Runx-2、ALP及OCN基因mRNA的表达显著高于对照组,而成脂因子PPARγ-2及LPL基因mRNA的表达显著低于对照组(P<0.05);Western-blot检测结果显示实验组PPARγ-2蛋白几乎无表达,而成骨转录分化因子Runx-2蛋白的表达则明显增强,与RT-PCR的结果一致。[结论]在一定条件下,DKK-1抗体可以促使脂肪细胞转分化为具有一定成骨活性的成骨细胞,这为防治激素性股骨头坏死提供了新的思路。     

A non-nephrotoxic gentamicin congener that retains antimicrobial efficacy

Aminoglycoside antibiotics, although of major clinical importance in the treatment of serious Gram- negative infections and a potential therapeutic agent in the amelioration of diseases that are characterized by premature stop mutations, are associated with a high incidence of acute renal failure. With the use of HPLC techniques, the four components (congeners) of gentamicin, the most commonly used aminoglycoside, were isolated and characterized. Described here is a congener with minimal cytotoxicity in cell culture and animal studies that retained normal bactericidal properties in both Bacillus subtilis and a multidrug-resistant form of Klebsiella pneumoniae. Furthermore, in animal studies, this congener failed to induce the functional and pathologic changes that are characteristic of gentamicin nephrotoxicity that is seen with the native compound. Finally, internalization of this non-nephrotoxic component was unaltered, but the subcellular distribution was different from native gentamicin or the other three cytotoxic congeners. These studies have identified a component of the native gentamicin congener mixture that retains its bactericidal properties with minimal or no apparent nephrotoxicity.     

Inorganic polyphosphate differentiates human mesenchymal stem cells into osteoblastic cells

The existence of inorganic polyphosphates [poly(P)] in human cells has been demonstrated. In osteoblasts, it is suggested that the concentration of cellular poly(P) is relatively high. In this study, we examined whether poly(P) accelerates the differentiation of human mesenchymal stem cells (hMSCs) from patients with osteoarthritis (OA) and rheumatoid arthritis (RA) into osteoblastic cells. Alkaline phosphatase (ALP) activity was induced by poly(P) in hMSCs from both OA and RA. In Alizarin Red S and osteocalcin EIA, there was a significant difference between the control and poly(P) group. In real-time PCR, there was a significant difference in ALP, collagen type 1A, osteocalcin, and bone sialoprotein between the control and poly(P) group. Our findings suggest that poly(P) have the potent role of differentiating hMSCs into osteoblastic cells at the early and later stages of osteoblastic differentiation.     

兔成骨细胞和脂肪细胞横向分化的研究

目的 探讨兔成骨细胞和脂肪细胞两者横向分化的能力和方法.方法 选取3个月龄新西兰大白兔,获取、分离培养脂肪细胞,天花板贴壁法使其去分化,去分化脂肪细胞进行成骨诱导3周后行茜素红、碱性磷酸酶(ALP)和Ⅰ型胶原酶免疫组织化学染色.另选取出生7d内的乳兔,取颅骨骨块利用酶消-组织块培养法培养成骨细胞并传代培养,对其进行成脂诱导3周后行油红O染色、逆转录-聚合酶链反应(RT-PCR)检测过氧化物酶体增殖物激活受体γ(PPARγ) mRNA的表达.结果 提取的成熟脂肪细胞去分化后为长梭形成纤维细胞状;成骨诱导后,Ⅰ型胶原免疫组织化学染色显示实验组细胞内表达出Ⅰ型胶原,与对照组比较差异有统计学意义(P＜0.05);各组细胞第3天、第7天、第14天不同时段的ALP活性实验组较对照组高(P＜0.05),分别为0.165±0.007、0.253±0.005、0.345±0.007和0.067±0.004、0.076±0.006、0.082±0.003,且随着培养时间的延长实验组ALP活性逐渐增强(组内比较P＜0.05);提取的乳兔颅骨成骨细胞呈短梭形,成脂诱导3周后油红O染色阳性,PPARγmRNA表达阳性,对照组为阴性,实验组与对照组比较差异有统计学意义(P＜0.05).结论 成熟脂肪细胞可以通过体外培养实现去分化,脂肪细胞和成骨细胞在一定条件下可以相互转化.     

Evidence that conditionally immortalized human osteoblasts express an osteocalcin receptor

Osteocalcin (OC) is an abundant noncollagenous bone matrix protein, yet its function is largely unknown. However, targeted ablation of two OC genes in mice lead to increased bone formation (Ducy et al. Nature 382:448-452; 1996). This implied that OC inhibits osteoblast activity, and that these cells express an OC receptor. In order to characterize the putative OC receptor, we used the Cytosensor microphysiometer to measure responses of a proliferative-stage, conditionally immortalized human osteoblast cell line (HOB-03-C5) to purified bovine OC (bOC). The Cytosensor measures a change in the extracellular acidification rate, which is primarily a measurement of metabolic activity. Treatment of the HOB cells for 5-60 sec with 0.17 micromol/L bOC generated a time-dependent, transient increase in the acidification rate that became optimal after 25 sec. Likewise, treatment of the cells for 25 sec with 0.021 to 1.9 micromol/L bOC caused a dose-dependent 70% increase in the acidification rate. Pre-treatment of the cells for 2 h with inhibitors of adenylyl cyclase, phospholipase C, and intracellular calcium release inhibited the response of the cells to bOC by 50%-100%, which suggested that the putative OC receptor was coupled to a G-protein. These observations from the Cytosensor were confirmed by measuring intracellular cyclic-adenosine monophosphate (cAMP) concentrations in response to bOC. Treatment of the cells for 10 min with bOC decreased basal cAMP levels by 65% in a dose-dependent manner with an IC50 of 0.22 microM. However, cotreatment of the cells with forskolin, which activates adenylyl cyclase, blunted this suppression. Moreover, pretreatment of the cells with pertussis toxin for 48 h, which inhibits G(alpha)i proteins, reversed the suppressive effects of bOC on cAMP production. Treatment of the HOB cells for 48 h with 0.19 to 1.5 micromol/L bOC caused a dose-dependent 40% decrease in alkaline phosphatase activity with an IC50 of 0.21 micromol/L, which suggested that OC may inhibit HOB activity. Finally, although the maturation stage, conditionally immortalized HOB-02-C1 cells also responded to bOC as measured by the Cytosensor, two osteosarcoma cell lines, SaOS-2 and ROS 17/2.8, exhibited a 5- to 10-fold lower response to the bone matrix protein, suggesting that the putative OC receptor was downregulated in these cells. However, all of these bone cell lines responded to parathyroid hormone treatment. In conclusion, these results provide evidence that the HOB cells express an OC receptor, and that this receptor appears to be coupled to a G(alpha)-protein.     

脆性组氨酸三联体基因FHIT对乳腺癌细胞株MCF-7的作用

目的 克隆人类脆性组氨酸三联体基因(FHIT)并构建其真核表达载体pcDNA3.1(+)/FHIT,将人FHIT基因转染人乳腺细胞MCF-7中稳定表达,检测转染后细胞生物学特性的变化.方法 构建FHIT基因表达载体pcDNA3.1(+)/FHIT,用脂质体法将FHIT基因的真核质粒表达载体pcDNA3.1(+)/FHIT导入人乳腺癌细胞MCF-7中,细胞计数、流式细胞术分析转染后细胞的生物学特性变化.结果 将逆转录-聚合酶链反应(RT-PCR)扩增后的产物克隆到表达载体peDNA 3.1(+)上,经PCR扩增筛选鉴定和测序鉴定证实为所需序列,转染乳腺癌MCF-7细胞后,FHIT基因的表达明显增强,细胞周期分析发现MCF-7/FHIT与MCF-7比较S期及G2/M期的细胞减少,G0/G1期的细胞增加,MCF-7/FHIT细胞的凋亡率为(29.75±5.90)%,MCF-7细胞的凋亡率为(11.21±6.10)%,和MCF-7比较,转染后的MCF-7/FHIT细胞的凋亡明显增加,MCF-7细胞的增殖明显抑制.结论 FHIT基因表达载体可有效抑制乳腺癌细胞MCF-7的增殖.     

Insertion of a suicide gene into an immortalized human hepatocyte cell line

For developing a bioartificial liver (BAL) device, an attractive alternative to the primary human hepatocytes would be the use of highly differentiated immortalized human hepatocytes with a safeguard. To test the feasibility, the primary human hepatocytes were immortalized by a plasmid SV3neo encoding simian virus 40 large T antigen (SV40Tag) gene. A highly differentiated hepatocyte line OUMS-29 was established. A suicide gene of herpes simplex virus-thymidine kinase (HSV-TK) was retrovirally introduced into OUMS-29 cells as a safeguard for clinical application. One of the resulting HSV-TK-positive cell lines, OUMS-29/tk, grew in chemically defined serum-free medium with the gene expression of differentiated liver functions. OUMS-29/tk cells were 100 times more sensitive to ganciclovir compared with unmodified OUMS-29 cells in in vitro experiments. We have established a tightly regulated immortalized human hepatocyte cell line. Essentially unlimited availability of OUMS-29/tk cells may be clinically useful for BAL therapy.     

Calcification in human osteoblasts cultured in medium conditioned by the prostatic cancer cell line PC-3 and prostatic acid phosphatase.

A medium that had been conditioned by PC-3 cells stimulated the calcification of a human osteoblastic cell line, Tak-10, in a nonmitogenic culture. The calcification of the osteoblasts was stimulated maximally at a 25% concentration of the conditioned medium. Calcification activity was markedly enhanced by the addition of both prostatic acid phosphatase (PAP) and its substrate, alpha-glycerophosphate, to the medium; however, PAP added alone did not enhance this activity. These results suggest that human prostatic carcinoma cells produce a factor that stimulates the calcification of the human osteoblasts. Results have also suggested that PAP is a requisite for osteogenesis provided that its substrates are abundant in the medium.     

人肝癌细胞株与正常肝细胞株MicroRNA差异表达谱研究

目的 建立SMMC-7721人肝癌细胞株与CCC-HEL-1人正常肝细胞株MicroRNA(miRNA)差异的表达谱,确定差异的miRNA,为进一步研究miRNA在肝细胞癌变机制中的作用和肝癌的治疗提供新的线索.方法 体外培养SMMC-7721人肝癌细胞株和CCC-HEL-1人正常肝细胞株.用TRIzol法提取细胞的总...     

小鼠胚胎瘤来源细胞系ATDC5的体外软骨分化诱导研究

目的 在体外建立稳定有效的软骨细胞分化模型.方法 复苏ATDC5细胞,在倒置显微镜下观察细胞形态及其生长情况,细胞90%融合时分别用不含Vc和含Vc的诱导培养基培养进行分化诱导.诱导21 d,阿力新蓝染色,RT-PCR检测Ⅱ、Ⅹ型胶原表达进行鉴定.结果 含50 μg/mL Vc的诱导培养基诱导1 周便可见明显的软骨小结,细胞产生软骨基质明显增多,Ⅱ及Ⅹ型胶原表达明显增高,且Ⅹ型胶原表达呈提前.结论 利用ATDC5细胞系可成功建立软骨细胞分化体外模型.     

A newly established human osteosarcoma cell line with osteoblastic properties

A human osteosarcoma cell line, HuO9, was established from a tumor that was heterotransplanted into athymic nude mice. Antiserum against nude mouse spleen cells was added to the early passage cultures to eliminate the host fibroblastic cells. The cell line retained a high activity of liver/bone/kidney-type alkaline phosphatase (ALP) and secreted osteocalcin, i.e., bone gamma-carboxyglutamic acid-containing protein (BGP), into the medium. The addition of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) increased the ALP activity as well as the level of BGP secreted into the medium. The ALP of 1,25(OH)2D3-treated cells has the same inhibition characteristics to heat and amino acids as that of untreated cells. Synthetic human parathyroid hormone stimulated the production of intracellular adenosine 3',5'-cyclic monophosphate (cAMP) approximately 100-fold within five minutes. However, the stimulation was not observed with a synthetic human thyrocalcitonin. When HuO9 cells were transplanted into the back of a nude mouse, a tumor with an abundant osteoid formation and mineralization was produced. The results indicate that the HuO9 cell line expresses well-differentiated osteoblastic phenotypes. HuO9 is the first established human cell line to produce BGP, and it provides a useful model for the studies of osteoblasts and the regulatory mechanisms of BGP production.     

Dexamethasone-induced lipolysis increases the adverse effect of adipocytes on osteoblasts using cells derived from human mesenchymal stem cells

The increased bone marrow lipid deposition in steroid-associated bone loss diseases indicates that abnormalities in fat metabolism are associated with disease development. Recent studies have suggested that bone marrow adipocytes are secretory cells and that they may release substances that have an inhibitory effect on the differentiation and function of osteoblasts. We hypothesized that exposure of bone-marrow-derived adipocytes to corticosteroids exacerbates their deleterious effects on osteoblast metabolism and function. Adipocytes and osteoblasts derived from a human mesenchymal stem cell line (240 L) were co-cultured in the absence of direct cell contact with or without dexamethasone treatment. After 6 days of co-culture, osteoblasts demonstrated significantly lower levels of function based on lower mineralization, alkaline phosphatase activity and expression of osteogenic (Runx2, osteocalcin) mRNA marker. Dexamethasone treatment resulted in significantly lower levels of osteoblastic function compared with co-cultured cells without dexamethasone. Furthermore, conditioned media from dexamethasone-treated adipocytes induced a similar toxic effect and increased apoptosis involving activation of caspases 3/7 compared with conditioned media without dexamethasone treatment. Within the conditioned media, a substantial increase in the levels of leptin and two saturated fatty acids (FAs; stearate and palmitate) was observed after dexamethasone treatment. Although leptin supplementation failed to induce the inhibitory effect on osteoblasts, similar toxic results were produced with stearate and palmitate treatment, and an increase in intracellular reactive oxygen species was observed. Stearate- and palmitate-induced apoptosis was blocked by a reactive oxygen species scavenger pyrrolidine dithiocarbamate. These data show that saturated FAs secreted from adipocytes induce lipotoxic effects via mechanisms that may involve reactive oxygen species accumulation in osteoblasts. Our results suggest that inhibition of saturated FA secretion would protect osteoblasts against adipocytes in corticosteroid-associated bone loss diseases.     

A conditionally immortalized human podocyte cell line demonstrating nephrin and podocin expression

Recent molecular insights have established the podocyte as a key component of the glomerular filtration barrier, and hence an important common pathway in proteinuric diseases. A conditionally immortalized human podocyte cell line has been developed by transfection with the temperature-sensitive SV40-T gene. These cells proliferate at the "permissive" temperature (33 degrees C). After transfer to the "nonpermissive" temperature (37 degrees C), they entered growth arrest and expressed markers of differentiated in vivo podocytes, including the novel podocyte proteins, nephrin, podocin, CD2AP, and synaptopodin, and known molecules of the slit diaphragm ZO-1, alpha-, beta-, and gamma-catenin and P-cadherin. The differentiation was accompanied by a growth arrest and the upregulation of cyclin-dependent kinase inhibitors, p27 and p57, as well as cyclin D(1), whereas cyclin A was downregulated. These data are consistent with cell cycle protein expression during podocyte maturation in vivo. In conclusion, the development of this cell line provides a new tool in the study of podocyte biology, which will enable accurate assessment of the behavior of these complex cells in health and disease.