Study on chondrogenic differentiation of canine mesenchymal stem cells induced by Type 2 recombinant adeno-associated viral mediated transfer of hTGF-β1

Objective To investigate the potential application of human transforming growth factor-beta-1 (hTGF-β1) gene mediated by type 2 recombinant adeno-associated virus (rAAV2) vector inducing chondrogenic differentiation of canine mesenchymal stem cells (MSCs) in vitro. Methods Canine MSCs from bone marrow were isolated and cultured in vitro by density gradient centrifngation and adherence screening methods. The morphology of MSCs was observed by inverted phase contrast microscope and Giemsa stain. Flow eytometry was used to detect surface antigens of MSCs, The third generation of MSCs were transfected by rAAV2-hTGF-β1 with or without MOI of 1 ×105 v.g./cell or 5×105 v.g./cell. The expression of hTGF-β1 was detected by Western blot after 10 days, and TGF-β1 synthesis was determined by ELISA at 3, 6 and 9 day, respectively. After 2 weeks of culturing, mRNA expressions of type Ⅱ collagen and aggrecan were determined by RT-PCR and the collagen Ⅱ protein was detected by immunocytochemistry. Results The MSCs appeared to be morphologically spindle-shaped and showed active capability of proliferation both in primary and passage generations. Flow cytometry analysis indicated that MSCs were universally positive for CD29, CD44 and CD105, but negative for CD34 and CD45. TGF-β1 expression can be observed by Western blot after 10 days in two transfection groups, MOI of 5 × 105 group and MOI of 1× 105 group. With the extension of time, the contents of hTGF-β1 increased in the two groups detected by ELISA, while there was a significant difference between them two (P < 0.01). After 2 weeks of transfection of MSCs by rAAV2-hTGF-β1, the expression of collagen Ⅱ and Aggreacan mRNAs were positive. It also showed positive of collagen Ⅱ detected by immunocytochemistry. Conclusion Canine MSCs show chondrogenesis differentiation after induction by Type 2 rAAV mediated transfer of TGF-β1 gene. The process is a potential application for cartilage tissue engineering.     

Study on chondrogenic differentiation of canine mesenchymal stem cells induced by Type 2 recombinant adeno-associated viral mediated transfer of hTGF-β1

Objective To investigate the potential application of human transforming growth factor-beta-1 (hTGF-β1) gene mediated by type 2 recombinant adeno-associated virus (rAAV2) vector inducing chondrogenic differentiation of canine mesenchymal stem cells (MSCs) in vitro. Methods Canine MSCs from bone marrow were isolated and cultured in vitro by density gradient centrifngation and adherence screening methods. The morphology of MSCs was observed by inverted phase contrast microscope and Giemsa stain. Flow eytometry was used to detect surface antigens of MSCs, The third generation of MSCs were transfected by rAAV2-hTGF-β1 with or without MOI of 1 ×105 v.g./cell or 5×105 v.g./cell. The expression of hTGF-β1 was detected by Western blot after 10 days, and TGF-β1 synthesis was determined by ELISA at 3, 6 and 9 day, respectively. After 2 weeks of culturing, mRNA expressions of type Ⅱ collagen and aggrecan were determined by RT-PCR and the collagen Ⅱ protein was detected by immunocytochemistry. Results The MSCs appeared to be morphologically spindle-shaped and showed active capability of proliferation both in primary and passage generations. Flow cytometry analysis indicated that MSCs were universally positive for CD29, CD44 and CD105, but negative for CD34 and CD45. TGF-β1 expression can be observed by Western blot after 10 days in two transfection groups, MOI of 5 × 105 group and MOI of 1× 105 group. With the extension of time, the contents of hTGF-β1 increased in the two groups detected by ELISA, while there was a significant difference between them two (P < 0.01). After 2 weeks of transfection of MSCs by rAAV2-hTGF-β1, the expression of collagen Ⅱ and Aggreacan mRNAs were positive. It also showed positive of collagen Ⅱ detected by immunocytochemistry. Conclusion Canine MSCs show chondrogenesis differentiation after induction by Type 2 rAAV mediated transfer of TGF-β1 gene. The process is a potential application for cartilage tissue engineering.     

Study on chondrogenic differentiation of canine mesenchymal stem cells induced by Type 2 recombinant adeno-associated viral mediated transfer of hTGF-β1

Objective To investigate the potential application of human transforming growth factor-beta-1 (hTGF-β1) gene mediated by type 2 recombinant adeno-associated virus (rAAV2) vector inducing chondrogenic differentiation of canine mesenchymal stem cells (MSCs) in vitro. Methods Canine MSCs from bone marrow were isolated and cultured in vitro by density gradient centrifngation and adherence screening methods. The morphology of MSCs was observed by inverted phase contrast microscope and Giemsa stain. Flow eytometry was used to detect surface antigens of MSCs, The third generation of MSCs were transfected by rAAV2-hTGF-β1 with or without MOI of 1 ×105 v.g./cell or 5×105 v.g./cell. The expression of hTGF-β1 was detected by Western blot after 10 days, and TGF-β1 synthesis was determined by ELISA at 3, 6 and 9 day, respectively. After 2 weeks of culturing, mRNA expressions of type Ⅱ collagen and aggrecan were determined by RT-PCR and the collagen Ⅱ protein was detected by immunocytochemistry. Results The MSCs appeared to be morphologically spindle-shaped and showed active capability of proliferation both in primary and passage generations. Flow cytometry analysis indicated that MSCs were universally positive for CD29, CD44 and CD105, but negative for CD34 and CD45. TGF-β1 expression can be observed by Western blot after 10 days in two transfection groups, MOI of 5 × 105 group and MOI of 1× 105 group. With the extension of time, the contents of hTGF-β1 increased in the two groups detected by ELISA, while there was a significant difference between them two (P < 0.01). After 2 weeks of transfection of MSCs by rAAV2-hTGF-β1, the expression of collagen Ⅱ and Aggreacan mRNAs were positive. It also showed positive of collagen Ⅱ detected by immunocytochemistry. Conclusion Canine MSCs show chondrogenesis differentiation after induction by Type 2 rAAV mediated transfer of TGF-β1 gene. The process is a potential application for cartilage tissue engineering.     

Growth differentiation factor-5 stimulates the growth and anabolic metabolism of articular chondrocytes

Objective： To observe the effect of growth differentiation factor-5 （GDF-5） on the growth and anabolic metabolism of articular chondrocytes. Methods： The articular chondrocytes isolated from rats were treated with various concentrations of rmGDF-5, and the growth of chondrocytes measured by MTT assay, the cellular cartilage matrices formation detected sulfated glycosaminoglycan by Alcian blue staining and type Ⅱ collagen by RT-PCR, the collagen phenotypic expression of chondrocytes detected by immunofluorescence. Results： After 7 days culture, MTT assay showed that GDF-5 enhanced the growth of chondrocytes in a dose-dependent manner, RT-PCR showed that GDF-5 clearly induced the synthesis of type Ⅱcollagen because of the col2al mRNA band more and more strong in a dose-dependent. Chondrocytes were cultured with GDF-5 for 14 days, the intensity of Alcian blue staining was greatly enhanced, especially, at a high concentration of 1000ng/ml, and GDF-5 enhanced the accumulation of the Alcian blue-stainable material in a concentration-dependent manner and in a does-dependent manner. Chondrocytes were cultured with GDF-5 for 21 days, immunofluorescent staining of type Ⅱ collagen was clear, the type Ⅰ and Ⅹ collagen were negative. Conclusion： GDF-5 enhanced the growth of mature articular chondrocytes, and stimulated the cellular cartilage matrices formation, but did not change the collagen phenotypic expression of chondrocytes in mono-layer culture.     

Study on chondrogenic differentiation of canine mesenchymal stem cells induced by Type 2 recombinant adeno-associated viral mediated transfer of hTGF-β1

Objective To investigate the potential application of human transforming growth factor-beta-1 (hTGF-β1) gene mediated by type 2 recombinant adeno-associated virus (rAAV2) vector inducing chondrogenic differentiation of canine mesenchymal stem cells (MSCs) in vitro. Methods Canine MSCs from bone marrow were isolated and cultured in vitro by density gradient centrifngation and adherence screening methods. The morphology of MSCs was observed by inverted phase contrast microscope and Giemsa stain. Flow eytometry was used to detect surface antigens of MSCs, The third generation of MSCs were transfected by rAAV2-hTGF-β1 with or without MOI of 1 ×105 v.g./cell or 5×105 v.g./cell. The expression of hTGF-β1 was detected by Western blot after 10 days, and TGF-β1 synthesis was determined by ELISA at 3, 6 and 9 day, respectively. After 2 weeks of culturing, mRNA expressions of type Ⅱ collagen and aggrecan were determined by RT-PCR and the collagen Ⅱ protein was detected by immunocytochemistry. Results The MSCs appeared to be morphologically spindle-shaped and showed active capability of proliferation both in primary and passage generations. Flow cytometry analysis indicated that MSCs were universally positive for CD29, CD44 and CD105, but negative for CD34 and CD45. TGF-β1 expression can be observed by Western blot after 10 days in two transfection groups, MOI of 5 × 105 group and MOI of 1× 105 group. With the extension of time, the contents of hTGF-β1 increased in the two groups detected by ELISA, while there was a significant difference between them two (P < 0.01). After 2 weeks of transfection of MSCs by rAAV2-hTGF-β1, the expression of collagen Ⅱ and Aggreacan mRNAs were positive. It also showed positive of collagen Ⅱ detected by immunocytochemistry. Conclusion Canine MSCs show chondrogenesis differentiation after induction by Type 2 rAAV mediated transfer of TGF-β1 gene. The process is a potential application for cartilage tissue engineering.     

Study on chondrogenic differentiation of canine mesenchymal stem cells induced by Type 2 recombinant adeno-associated viral mediated transfer of hTGF-β1

Objective To investigate the potential application of human transforming growth factor-beta-1 (hTGF-β1) gene mediated by type 2 recombinant adeno-associated virus (rAAV2) vector inducing chondrogenic differentiation of canine mesenchymal stem cells (MSCs) in vitro. Methods Canine MSCs from bone marrow were isolated and cultured in vitro by density gradient centrifngation and adherence screening methods. The morphology of MSCs was observed by inverted phase contrast microscope and Giemsa stain. Flow eytometry was used to detect surface antigens of MSCs, The third generation of MSCs were transfected by rAAV2-hTGF-β1 with or without MOI of 1 ×105 v.g./cell or 5×105 v.g./cell. The expression of hTGF-β1 was detected by Western blot after 10 days, and TGF-β1 synthesis was determined by ELISA at 3, 6 and 9 day, respectively. After 2 weeks of culturing, mRNA expressions of type Ⅱ collagen and aggrecan were determined by RT-PCR and the collagen Ⅱ protein was detected by immunocytochemistry. Results The MSCs appeared to be morphologically spindle-shaped and showed active capability of proliferation both in primary and passage generations. Flow cytometry analysis indicated that MSCs were universally positive for CD29, CD44 and CD105, but negative for CD34 and CD45. TGF-β1 expression can be observed by Western blot after 10 days in two transfection groups, MOI of 5 × 105 group and MOI of 1× 105 group. With the extension of time, the contents of hTGF-β1 increased in the two groups detected by ELISA, while there was a significant difference between them two (P < 0.01). After 2 weeks of transfection of MSCs by rAAV2-hTGF-β1, the expression of collagen Ⅱ and Aggreacan mRNAs were positive. It also showed positive of collagen Ⅱ detected by immunocytochemistry. Conclusion Canine MSCs show chondrogenesis differentiation after induction by Type 2 rAAV mediated transfer of TGF-β1 gene. The process is a potential application for cartilage tissue engineering.     

Study on chondrogenic differentiation of canine mesenchymal stem cells induced by Type 2 recombinant adeno-associated viral mediated transfer of hTGF-β1

Objective To investigate the potential application of human transforming growth factor-beta-1 (hTGF-β1) gene mediated by type 2 recombinant adeno-associated virus (rAAV2) vector inducing chondrogenic differentiation of canine mesenchymal stem cells (MSCs) in vitro. Methods Canine MSCs from bone marrow were isolated and cultured in vitro by density gradient centrifngation and adherence screening methods. The morphology of MSCs was observed by inverted phase contrast microscope and Giemsa stain. Flow eytometry was used to detect surface antigens of MSCs, The third generation of MSCs were transfected by rAAV2-hTGF-β1 with or without MOI of 1 ×105 v.g./cell or 5×105 v.g./cell. The expression of hTGF-β1 was detected by Western blot after 10 days, and TGF-β1 synthesis was determined by ELISA at 3, 6 and 9 day, respectively. After 2 weeks of culturing, mRNA expressions of type Ⅱ collagen and aggrecan were determined by RT-PCR and the collagen Ⅱ protein was detected by immunocytochemistry. Results The MSCs appeared to be morphologically spindle-shaped and showed active capability of proliferation both in primary and passage generations. Flow cytometry analysis indicated that MSCs were universally positive for CD29, CD44 and CD105, but negative for CD34 and CD45. TGF-β1 expression can be observed by Western blot after 10 days in two transfection groups, MOI of 5 × 105 group and MOI of 1× 105 group. With the extension of time, the contents of hTGF-β1 increased in the two groups detected by ELISA, while there was a significant difference between them two (P < 0.01). After 2 weeks of transfection of MSCs by rAAV2-hTGF-β1, the expression of collagen Ⅱ and Aggreacan mRNAs were positive. It also showed positive of collagen Ⅱ detected by immunocytochemistry. Conclusion Canine MSCs show chondrogenesis differentiation after induction by Type 2 rAAV mediated transfer of TGF-β1 gene. The process is a potential application for cartilage tissue engineering.     

Study on chondrogenic differentiation of canine mesenchymal stem cells induced by Type 2 recombinant adeno-associated viral mediated transfer of hTGF-β1

Objective To investigate the potential application of human transforming growth factor-beta-1 (hTGF-β1) gene mediated by type 2 recombinant adeno-associated virus (rAAV2) vector inducing chondrogenic differentiation of canine mesenchymal stem cells (MSCs) in vitro. Methods Canine MSCs from bone marrow were isolated and cultured in vitro by density gradient centrifngation and adherence screening methods. The morphology of MSCs was observed by inverted phase contrast microscope and Giemsa stain. Flow eytometry was used to detect surface antigens of MSCs, The third generation of MSCs were transfected by rAAV2-hTGF-β1 with or without MOI of 1 ×105 v.g./cell or 5×105 v.g./cell. The expression of hTGF-β1 was detected by Western blot after 10 days, and TGF-β1 synthesis was determined by ELISA at 3, 6 and 9 day, respectively. After 2 weeks of culturing, mRNA expressions of type Ⅱ collagen and aggrecan were determined by RT-PCR and the collagen Ⅱ protein was detected by immunocytochemistry. Results The MSCs appeared to be morphologically spindle-shaped and showed active capability of proliferation both in primary and passage generations. Flow cytometry analysis indicated that MSCs were universally positive for CD29, CD44 and CD105, but negative for CD34 and CD45. TGF-β1 expression can be observed by Western blot after 10 days in two transfection groups, MOI of 5 × 105 group and MOI of 1× 105 group. With the extension of time, the contents of hTGF-β1 increased in the two groups detected by ELISA, while there was a significant difference between them two (P < 0.01). After 2 weeks of transfection of MSCs by rAAV2-hTGF-β1, the expression of collagen Ⅱ and Aggreacan mRNAs were positive. It also showed positive of collagen Ⅱ detected by immunocytochemistry. Conclusion Canine MSCs show chondrogenesis differentiation after induction by Type 2 rAAV mediated transfer of TGF-β1 gene. The process is a potential application for cartilage tissue engineering.     

骨形态发生蛋白-2和转化生长因子-β1双基因共表达对骨髓基质细胞向软骨细胞分化基因表达的影响

目的 观察骨形态发生蛋白-2(BMP-2)和转化生长因子-β1 (TGF-β1)双基因真核共表达载体对兔骨髓基质细胞(MSCs)向软骨细胞分化mRNA表达的影响。方法 pIRES-BMP-2-TGF-β1、pIREES-BMP-2 and pIRES-TGF-β1质粒通过质脂体介导转染MSCs,采用荧光定量逆转录-聚合酶链反应(RT-PCR)方法检测MSCs内Ⅱ型胶原和蛋白多糖mRNA的表达。结果 转染后2、4d双基因组MSCs内的Ⅱ型胶原和蛋白多糖mRNA表达量60.4±10.1、606.0±88.5和42.6±6.0、411.2±73.6均明显高于转染后单一BMP-2(28.7±4.0、236.7±48.5和26.9±4.3、208.2±36.7)及TGF-β1(30.9±4.54、205.5±38.7和28.4±3.7、184.9±30.9)组(P＜0.05)。结论 pIRES-BMP-2-TGF-β1双基因真核共表达载体诱导MSCs向软骨细胞分化的作用强于单一基因BMP-2及TGF-β1。     

Enhanced matrix synthesis and in vitro formation of cartilage-like tissue by genetically modified chondrocytes expressing BMP-7.

Bone morphogenic protein-7 (BMP-7) supports ectopic cartilage and bone formation, is expressed in normal articular cartilage, and increases matrix synthesis in chondrocytes. Based on this knowledge, we hypothesized that an adenovirus (Ad) vector encoding human BMP-7 could be used to modify chondrocytes genetically to improve their capacity for cartilage repair. An adenovirus vector encoding BMP-7 (AdBMP-7) was constructed and its bioactivity confirmed by ectopic bone formation assay. AdBMP-7 modification of bovine chondrocytes induced expression of BMP-7 mRNA and bioactive protein, resulting in an increase in incorporation of 35SO4- into proteoglycan, 3H-proline uptake into protein, and the expression of the cartilage-specific matrix genes, aggrecan and type II collagen. An in vitro model of chondrocyte transplantation was used to demonstrate the feasibility of using genetically modified chondrocytes to enhance formation of cartilage-like tissue. When transplanted onto cartilage explants and maintained in vitro for 3 weeks, chondrocytes modified with AdBMP-7 formed 1.9-fold thicker tissue than chondrocytes modified with a control vector (P < 0.001). This tissue was positive for type II collagen and proteoglycan but negative for type X collagen and demonstrated a cartilage-like morphology. These observations suggest that Ad-mediated transfer of BMP-7 gene to chondrocytes enhances the chondrocyte-specific matrix synthesis and their capacity to form cartilage-like tissue, thus representing a strategy that may improve cell-based cartilage repair.     

非接触共培养脊索细胞诱导骨髓间充质干细胞向类软骨细胞分化的实验研究

目的:分离兔髓核脊索细胞(notochordal cells,NC)及骨髓间充质干细胞(mesenchymal stem cell,MSC),通过非接触共培养探讨NC对MSC细胞表型的影响。方法:4～6周龄新西兰兔8只,取胸腰段脊柱的髓核,用密度梯度离心提取NC,同时取其股骨骨髓用FICOLL液分离MSC,将NC和MSC等比例(1∶1)通过transwell培养板进行非接触共培养作为实验组,单纯MSC细胞培养作为对照组,光镜下观察细胞的生长情况。对两组的MSC行免疫组化及RT-PCR、Western-blot检测MSC细胞表型的改变情况。结果:原代NC呈圆形或椭圆形,细胞体积大,细胞增殖不明显;MSC贴壁生长,呈三角形或梭形,漩涡状排列。甲苯胺蓝染色:对照组MSC细胞核淡染,胞体染色不明显,染色阴性;实验组MSC可见从第3天开始胞体及胞外基质出现紫红色,第5天染色更加明显。Ⅱ型胶原免疫组化对照组MSC淡染,细胞形态不清楚;实验组第3天出现MSC内出现棕黄色深染,随着时间推移细胞染色加深呈阳性表现。RT-PCR检测,经过5d非接触共培养后实验组蛋白聚糖的基因表达为对照组的2.35倍(P<0.05),Ⅱ型胶原的基因表达为对照组的1.61倍(P<0.05),对照组Ⅰ型胶原的基因表达为实验组的2.56倍(P<0.05)。Western-blot检测后发现:经过5d非接触共培养,实验组蛋白聚糖的含量为对照组的1.61倍(P<0.05),Ⅱ型胶原的表达为对照组的10.04倍(P<0.05)(P<0.05)。结论:在非接触共培养条件下脊索细胞可以诱导骨髓间充质干细胞表型发生变化,向类软骨细胞方向分化,这将为组织工程化髓核的种子细胞筛选提供新选择。     

Statin stimulates bone morphogenetic protein-2, aggrecan,and type 2 collagen gene expression and proteoglycan synthesis in rat chondrocytes

Statins increase bone morphogenetic protein-2 (BMP-2) mRNA expression and subsequently increase new bone formation in vitro. However, the action of statins on the BMP-2 mRNA regulation of cartilage matrix synthesis by chondrocytes is unknown. We evaluated regulation of BMP-2, aggrecan, and type II collagen (COL2) mRNA and ³⁵S-labeled proteoglycan (PG) synthesis by mevastatin using cultured chondrocytes obtained from articular cartilage of fetal rats. Expression of BMP-2, aggrecan, and COL2 mRNAs were increased in the presence of 2µM mevastatin on day 2. However, longer (10 day) culture in the presence of the drug decreased the expression of these mRNAs. PG synthesis was increased 3 days after treating the cells with mevastatin, which was also decreased with longer (10 day) mevastatin treatment. These results suggest that mevastatin increases mRNA expression of BMP-2, aggrecan, and COL2 as well as PG synthesis by fetal rat chondrocytes early in the treatment period. We suggest that statins have implications for fracture and cartilage repair.     

The AdLMP-1 transfection in two different cells; AF cells,chondrocytes as potential cell therapy candidates for disc degeneration

Summary   Background. LMP-1 is known to increase proteoglycan production through the upregulating the BMPs and it is also known that BMP-2 acts on anulus fibrosus cells and chondrocytes to increase proteoglycan production. Method. We carried out an experiment, the effect of AdLMP-1 transfection on AF cells and chondrocytes in the production of sulfated-glycosaminoglycans, mRNA expression (aggrecan, type I, II collagen, LMP-1, BMP-2, and BMP-7), and immunofluorescence staining. AF cells and chondrocytes were grown in monolayer and treated for 6 days with AdLMP1-green fluorescence protein (GFP) (10, 20, and 30 multiplicity of infection [MOI]). After 6 days, the sGAG content in the media was quantified using 1,9-dimethylmethylene blue staining. The mRNA expression was measured with real-time PCR after 20 MOI infection of AdLMP1-GFP. The each cells treated with 20 MOI infection of AdGFP was used as a control group for the mRNA expression. The each cell group was immunofluorescence stained with each antibodies in the chamber slide at 3 × 10⁴ cells/chamber. Findings. 1) The sGAG production was maximum in 20 MOI AdLMP1-GFP infection on the AdLMP-1 treatment for both of AF cells and chondrocytes. 2) The mRNA expression of aggrecan, type I collagen, type II collagen, LMP-1, BMP-2, and BMP-7 is increased in both AF cells and chondrocytes in 20 MOI AdLMP1-GFP infection. 3) On the immunofluorescence staining results, the positive immunofluorescence stained cell numbers are increased after 20 MOI AdLMP1-GFP infection concordant with upregulation of mRNA expression. Conclusions. The AdLMP-1 treatments in AF cells and chondrocytes may be useful for cell transplantation therapy in disc degeneration. Correspondence: S. Tim Yoon M.D., Ph.D., Emory Orthopaedics and Spine Center, 59 Executive Park South, Atlanta 30329, GA.     

Chondrogenic potential of human synovial mesenchymal stem cells in alginate

OBJECTIVE: In a recent study, we demonstrated that mesenchymal stem cells (MSCs) derived from the synovial membranes of bovine shoulder joints could differentiate into chondrocytes when cultured in alginate. The purpose of the present study was to establish the conditions under which synovial MSCs derived from aging human donors can be induced to undergo chondrogenic differentiation using the same alginate system. METHODS: MSCs were obtained by digesting the knee-joint synovial membranes of osteoarthritic human donors (aged 59-76 years), and expanded in monolayer cultures. The cells were then seeded at a numerical density of 4x10(6)/ml within discs of 2% alginate, which were cultured in serum-containing or serum-free medium (the latter being supplemented with 1% insulin, transferrin, selenium (ITS). The chondrogenic differentiation capacity of the cells was tested by exposing them to the morphogens transforming growth factor-beta1 (TGF-beta1), TGF-beta2, TGF-beta3, insulin-like growth factor-1 (IGF-1), bone morphogenetic protein-2 (BMP-2) and BMP-7, as well as to the synthetic glucocorticoid dexamethasone. The relative mRNA levels of collagen types I and II, of aggrecan and of Sox9 were determined quantitatively by the real-time polymerase chain reaction (PCR). The extracellular deposition of proteoglycans was evaluated histologically after staining with Toluidine Blue, and that of type-II collagen by immunohistochemistry. RESULTS: BMP-2 induced the chondrogenic differentiation of human synovial MSCs in a dose-dependent manner. The response elicited by BMP-7 was comparable. Both of these agents were more potent than TGF-beta1. A higher level of BMP-2-induced chondrogenic differentiation was achieved in the absence than in the presence of serum. In the presence of dexamethasone, the BMP-2-induced expression of mRNAs for aggrecan and type-II collagen was suppressed; the weaker TGF-beta1-induced expression of these chondrogenic markers was not obviously affected. CONCLUSIONS: We have demonstrated that synovial MSCs derived from the knee joints of aging human donors possess chondrogenic potential. Under serum-free culturing conditions and in the absence of dexamethasone, BMP-2 and BMP-7 were the most potent inducers of this transformation process.     

Development of a new method to harvest chondroprogenitor cells from underneath cartilage defects in the knees

Background  Mesenchymal progenitor cells from bone marrow hold great potential as a cell source for cartilage repair. Aspiration from the iliac crest is the most widely used method to harvest bone marrow cells for cartilage repair. The objective of our study was to establish a new method to isolate mesenchymal progenitor cells by direct aspiration of bone marrow from the subchondral spongious bone underneath cartilage defects during microfracture treatment and to confirm the chondrogenic potential of the resulting cell cultures. Methods  Bone marrow was aspirated arthroscopically from patients treated for isolated cartilage defects. Adherent stromal cells were isolated, expanded in monolayer cultures, and characterized by flow cytometry. Chondrogenic induction of cells was achieved by combination of spheroid cultures in hanging drops and the concomitant use of transforming growth factor-β (TGFβ). Articular chondrocytes established in three-dimensional (3D) cultures were used as positive cartilage-forming units, and skin fibroblasts were used as negative controls. Three-dimensional constructs were stained for immunohistochemical and histological examination, and a real-time polymerase chain reaction (PCR) was performed to quantify the expression of aggrecan, collagen types 1 and 2, and Sox9. Results  Mesenchymal stem cell-like progenitor cells (MSCs) displaying chondrogenic differentiation capacity were harvested arthroscopically from underneath cartilage lesions on distal femurs using the one-hole technique. Stem cell-related surface antigens analyzed by flow cytometry confirmed the nature of the isolated adherent cells. MSC spheroids stained positive for glycosaminoglycans and collagen type 2. Realtime PCR showed that MSCs in 3D spheroids significantly increased gene expression of collagen type 2, aggrecan, and Sox 9 and down-regulated expression of collagen type 1 when compared to the mRNA levels measured in MSCs monolayers. Conclusions  We describe a new technique that may be applied for harvesting bone marrow cells from cartilage defects during arthroscopic intervention of the knee. Cells harvested in this way hold full chondrogenic differentiation potential. Our data imply that MSC storage may be established by using marrow from this approach, bypassing the need for cell aspiration from the iliac crest.     

Bone morphogenetic protein 2 induces placental growth factor in mesenchymal stem cells

Bone-forming osteoblasts differentiate from pluripotent mesenchymal stem cells (MSCs) in a multistage process that can be modeled in vitro using MSCs isolated from adult human trabecular bone or bone marrow. To identify new genes involved in osteoblast differentiation, we have performed large-scale gene expression profiling using high-density cDNA microarrays in primary human MSCs treated with the known osteogenic agent bone morphogenetic protein 2 (BMP-2). The vascular endothelial growth factor (VEGF) family member placental growth factor (PlGF) was found as an early regulated gene whose induction was already detected after 2 h treatment with BMP-2. Tissue distribution analysis of PlGF mRNA expression using microarrays revealed a very restricted expression of PlGF only in BMP-2-treated MSCs and in placenta as expected. Ribonuclease protection assay (RPA) confirmed the induction of PlGF and showed preferential expression of the PlGF-1 isoform over PLGF-2 in MSCs and MG63 cells. BMP-2 stimulated PlGF expression in MG63 cells with an EC50 of about 50 ng/ml and mRNA levels peaked between 24 and 32 h after stimulation. Furthermore, induction of PlGF by BMP-2 appeared specific, as other osteogenic agents including vitamin D3, transforming growth factor beta, and basic fibroblast growth factor were inactive. BMP-2 stimulated PlGF secretion from MG63 and MSC cells, but PlGF had no effect on MSC proliferation and osteoblastic differentiation. Based on the known function of PlGF in the recruitment of endothelial and hematopoietic stem cells, these results suggest a paracrine role for MSC-derived PlGF in the angiogenesis and hematopoiesis that accompany BMP-2-induced bone formation.     

A comparison of three cell types as potential candidates for intervertebral disc therapy: annulus fibrosus cells, chondrocytes, and bone marrow derived cells

ObjectivesCandidate cell types for disc cell transplantation therapy include anulus fibrosus (AF) cells, chondrocytes, and bone marrow derived cells (BMDCs). We compared the disc matrix production in these three types of cells, before and after stimulation with rhBMP-2. There is no study extant that compares these three cell types to determine the best candidate for the disc cell therapy.MethodsAF cells, chondrocytes, and BMDCs (iliac crest and femur) were isolated and grown in monolayer. They were treated for 3 days with rhBMP-2. After 3 days, proteoglycan (sGAG) content in the media was quantified. The results were normalized by cell numbers. The mRNA expression of aggrecan, type I collagen, and type II collagen was measured using real-time PCR.Each cell type was also cultured in chamber slides and immunostained for aggrecan, type I collagen, and type II collagen after 3 days of treatment with rhBMP-2.Results(1) Without rhBMP-2 the chondrocytes produced more proteoglycan (sGAG) as compared to the other two cell types (AF cells and BMDCs). After stimulation with rhBMP-2 the chondrocytes produce even more proteoglycan than the other two cell types. (2) As compared to the other two cell types, in terms of mRNA expression, the chondrocytes expressed more aggrecan, type I collagen, and type II collagen before stimulation with rhBMP-2. After rhBMP-2 stimulation, the chondrocytes expressed even more aggrecan, type I collagen, and type II collagen in proportion to the concentration of rhBMP-2. For the BMDCs there were no changes in type I and II collagen. (3) rhBMP-2 stimulation produced increases in the protein levels of aggrecan, type I and II collagen in all three types of cells.ConclusionsOn balance, according to these results, it would seem that chondrocytes are the best candidate for the disc cell therapy.     

机械力学刺激对软骨细胞表型稳定性的影响

目的 观察不同类型机械力学刺激对兔软骨细胞表型稳定性的影响.方法 酶消化法获取兔膝关节软骨细胞培养传代,将第5代软骨细胞置于四点弯曲细胞培养板上以一定频率(0、1Hz)和大小(500、1000、1500με)的机械压力下培养、传代.免疫组织化学观察软骨细胞中Ⅰ、Ⅱ型胶原,聚合酶链反应(PCR)检测软骨细胞中Ⅰ、Ⅱ型胶原、蛋白聚糖mRNA的表达.结果 常规培养的软骨细胞传代至第5代以后,去分化失去表型.在动态机械应力刺激下,培养至第8代仍能表达Ⅱ型胶原、蛋白聚糖.结论 一定的机械力学刺激能维持软骨细胞的合成分泌功能,有助于软骨细胞表型的稳定.

Abstract：

Objective To explore the stability of chondrocyte phenotypes by the mechanical stimulation.Methods Rabbit knee articular cartilage cells obtained by enzymatic digestion were cultured and passaged. The chondrocytes were cultivated in unvarying (0, 1 Hz) frequency and different mechanical pressure (500, 1000, 1500 με) on four-point bending cell culture plate. Chondrocyte collagen type Ⅰ and type Ⅱ were analyzed immunohistochemically, and collagen Ⅰ, Ⅱ and proteoglycan mRNA expression was detected by polymerase chain reaction (PCR).Results Regularly cultured chondrocytes to the 5th generation or later lost phenotypes to differentiation. After stimulation by the dynamic mechanical stress, cartilage cells to the 8th generation still expressed the type Ⅱ collagen and proteoglycans.Conclusion Mechanics can stimulate the synthesis of chondrocytes and maintain the stability of chondrocyte phenotype.