Characterization of human nasal septal chondrocytes cultured in alginate

BACKGROUND: After serial passages in monolayer, chondrocytes dedifferentiate into a fibroblast-like phenotype. Our objective was to determine if culture in alginate affects the phenotype of dedifferentiated human nasal septal chondrocytes. STUDY DESIGN: Human nasal septal chondrocytes were seeded at low density and passaged in monolayer culture. At passages (P) 1, 2, and 3 a portion of cells were cultured in alginate. Collagen, glycosaminoglycan (GAG), and DNA production were assessed. RESULTS: Chondrocytes in alginate proliferated less yet produced higher levels of GAG and collagen than those in monolayer culture. Alginate encapsulated P1 chondrocytes stained strongly for GAG and collagen type II, and minimally for collagen type I. Monolayer cells at P0 and P1 stained positively for collagen type II. All monolayer passages stained positive for collagen type I with minimal GAG staining. CONCLUSIONS: Compared with monolayer culture, alginate stimulates deposition of GAG and collagen type II, and supports the chondrocyte phenotype through P1, but does not promote redifferentiation.     

人髂骨生长板软骨细胞的体外培养及鉴定

[目的]探讨人髂骨生长板软骨细胞体外培养的可行性并观察其生物学特征。[方法]对手术中获得的10例青少年特发性脊柱侧凸患者髂骨生长板软骨行体外分离、培养，观察细胞形态，MTT法测定细胞增殖，Ⅱ型胶原免疫组化染色，采用逆转录聚合酶链反应检测各代细胞Ⅱ型胶原mRNA的表达水平。[结果]（1）体外培养的软骨细胞随着传代次数的增加，细胞形态由原代的多角形逐渐变为长梭形；（2）MTT比色法检测显示，第2代髂软骨细胞的生长曲线近似倒“S”形，在第4～8d细胞呈对数生长，在9～10d达平台期，至第11d开始出现生长抑制。（3）第2代细胞Ⅱ型胶原免疫组化呈强阳性。（4）Ⅱ型胶原mRNA表达水平从第2代后随着传代次数的增加逐渐下降。[结论]采用联合酶序贯消化法将软骨细胞悬液和软骨块共同体外培养髂软骨细胞简单、有效，P2代细胞很好的保持了软骨细胞的特性，可以作为种子细胞来源。     

Culture temperature affects redifferentiation and cartilaginous extracellular matrix formation in dedifferentiated human chondrocytes

To date, there have been few studies on how temperature affects the phenotype and metabolism of human chondrocytes. Thus, the purpose of this study was to elucidate the effects of culture temperature on chondrocyte redifferentiation and extracellular matrix (ECM) formation using dedifferentiated mature human chondrocytes in vitro. Dedifferentiated chondrocytes were cultured in a pellet culture system for up to 21 days. The pellets were randomly divided into three groups with different culture temperature (32, 37, and 41°C). Chondrocyte redifferentiation and ECM formation were evaluated by wet weight, messenger ribonucleic acid (mRNA), histological, and biochemical analyses. The results showed that the wet weight and the mRNA expressions of collagen type II A1 and cartilage oligomeric matrix protein at 37°C were higher than the corresponding values at 32°C. The histological and biochemical analyses revealed that the syntheses of type II collagen and proteoglycan were promoted at 37°C compared to those at 32°C, whereas they were considerably inhibited at 41°C. In conclusion, the results obtained herein indicated that temperature affects chondrocyte redifferentiation and ECM formation, and modulation of temperature might thus represent an advantageous means to regulate the phenotype and biosynthetic activity of chondrocytes. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:633–639, 2015.     

The culture of articular chondrocytes in hydrogel constructs within a bioreactor enhances cell proliferation and matrix synthesis

Bovine and human articular chondrocytes were seeded in 2% alginate constructs and cultured for up to 19 days in a rotating-wall-vessel (RWV) and under static conditions. Culture within the RWV enhanced DNA levels for bovine chondrocyte-seeded constructs when compared with static conditions but did not produce enhancement for human cells. There was a significant enhancement of glycosaminoglycans and hydroxyproline synthesis for both bovine and human chondrocytes. In all cases, histological analysis revealed enhanced Safranin-O staining in the peripheral regions of the constructs compared with the central region. There was an overall increase in staining intensity after culture within the RWV compared with static conditions. Type-II collagen was produced by both bovine and human chondrocytes in the peripheral and central regions of the constructs and the staining intensity was enhanced by culture within the RWV. A capsule of flattened cells containing type-I collagen developed around the constructs maintained under static conditions when seeded with either bovine or human chondrocytes, but not when cultured within the RWV bioreactor.     

Autologous chondrocyte implantation. Culture in a TGF-beta-containing medium enhances the re-expression of a chondrocytic phenotype in passaged human chondrocytes in pellet culture

An increasing number of patients are treated by autologous chondrocyte implantation (ACI). This study tests the hypothesis that culture within a defined chondrogenic medium containing TGF-beta enhances the re-expression of a chondrocytic phenotype and the subsequent production of cartilaginous extracellular matrix by human chondrocytes used in ACI. Chondrocytes surplus to clinical requirements for ACI from 24 patients were pelleted and cultured in either DMEM (Dulbecco's modified eagles medium)/ITS+Premix/TGF-beta1 or DMEM/10%FCS (fetal calf serum) and were subsequently analysed biochemically and morphologically. Pellets cultured in DMEM/ITS+/TGF-beta1 stained positively for type-II collagen, while those maintained in DMEM/10%FCS expressed type-I collagen. The pellets cultured in DMEM/ITS+/TGF-beta1 were larger and contained significantly greater amounts of DNA and glycosaminoglycans. This study suggests that the use of a defined medium containing TGF-beta is necessary to induce the re-expression of a differentiated chondrocytic phenotype and the subsequent stimulation of glycosaminoglycan and type-II collagen production by human monolayer expanded chondrocytes.     

Culture and differentiation of chondrocytes entrapped in alginate gels

Summary We studied the response to culture conditions and the differentiative ability in suspension culture in alginate gels of resting chondrocytes from the preosseous cartilage of adult pig scapula. It was found that the maximum rate of chondrocyte duplication is reached at the fourth day in culture whereas the rate of proteoglycan synthesis and alkaline phosphatase expression do not gain a maximum value before the seventh day. During the culture time, the chondrocytes undergo differentiation as it is demonstrated by the alkaline phosphatase specific activity increase and by morphological criteria (hypertrophy, increase of the number of mitochondria per cell, increased endoplasmic reticulum, matrix vesicle production). The alginate gels can be easily dissolved to obtain cell populations in which the variation of cytosolic calcium concentration following a proliferative stimulus can be conveniently observed using the conventional procedure of Fura 2.     

Culture of chondrocytes in alginate and collagen carrier gels

In this in vitro study, we compared the potential of collagen and alginate gels as carriers for chondrocyte transplantation and we studied the influence of demineralized bone matrix (DBM) on chondrocytes in the gels. Chondrocytes were assessed for cell viability, phenotype (histology), proliferation rate and sulfate incorporation.

Collagen gels showed a significant increase in cell numbers, but the chondrocytes dedifferentiated into fibroblast-like cells from day 6 onwards. In alginate gels, initial cell loss was found, but the cells maintained their typical chondrocyte phenotype. Although the total quantity of proteoglycans initially synthesized per cell in collagen gel was significantly higher, expressed per cell, the quantity in alginate gel eventually surpassed collagen. No effects of culturing chondrocytes in combination with DBM could be demonstrated on cell proliferation and sulfate incorporation.

The collagen and alginate gels have different advantages as carriers for chondrocyte transplantation. The high proliferation rate of chondrocytes in collagen gel may be an advantage, but the preservation of the chondrocyte phenotype and the gradually increasing proteoglycan synthesis in alginate gel is a promising method for creating a hyaline cartilage implant in vitro.     

Effects of serial expansion of septal chondrocytes on tissue-engineered neocartilage composition.

OBJECTIVES: Cartilage grafts for reconstructive surgery may someday be created from harvested autologous chondrocytes that are expanded and seeded onto biodegradable scaffolds in vitro. This study sought to quantify the biochemical composition of neocartilage engineered from human septal chondrocytes and to examine the effects of cell multiplication in monolayer culture on the ultimate composition of the neocartilage. METHODS: Human septal chondrocytes from 10 donors were either seeded immediately after harvest (passage 0 [P(0)]) onto polyglycolic acid (PGA) scaffolds or underwent multiplication in monolayer culture before scaffold seeding at passage 1 (P(1)) and passage 2 (P(2)). Cell/scaffold constructs were grown in vitro for 7, 14, and 28 days. Neocartilage constructs underwent histologic analysis for matrix sulfated glycosaminoglycan (S-GAG) and type II collagen as well as quantitative assessment of cellularity (Hoescht 33258 assay), S-GAG content (dimethylmethylene blue assay), and collagen content (hydroxyproline assay). RESULTS: Histologic sections of constructs seeded with P(0) cells stained strongly for S-GAG and type II collagen, whereas decreased staining for both matrix components was observed in constructs derived from P(1) and P(2) cells. Cellularity, S-GAG content, and total collagen content of constructs increased significantly from day 7 to day 28. S-GAG accumulation in P(0) constructs was higher than in either P(1) (P < 0.05) or P(2) (P < 0.01) constructs, whereas cellularity and total collagen content showed no difference between passages. CONCLUSION: Neocartilage created from chondrocytes that have undergone serial passages in monolayer culture exhibited decreased matrix S-GAG and type II collagen, indicative of cellular dedifferentiation. SIGNIFICANCE: The alterations of matrix composition produced by dedifferentiated chondrocytes may limit the mechanical stability of neocartilage constructs.     

大鼠软骨细胞与兔软骨细胞的培养与比较

目的 体外分离培养大鼠及兔膝关节软骨细胞,观察并比较两种软骨细胞的培养特点。方法 采用机械-酶消化法处理SD大鼠幼鼠和新西兰兔的软骨组织,传代培养,倒置显微镜观察细胞形态,细胞计数法测定生长曲线,实时定量PCR测定不同代数的软骨细胞Ⅱ型胶原与含血小板结合蛋白基序的解聚蛋白样金属蛋白酶5（a disintegrin and metalloproteinase with thrombospondin motifs 5, ADAMTS5）表达水平,甲苯胺蓝染色及Ⅱ型胶原酶免疫荧光染色对细胞进行鉴定。结果 原代培养大鼠软骨细胞12 h,内贴壁成多角形或不规则型,排列成“铺路石”状,培养3~5 d后进入快速增殖期,1周后进行细胞传代培养。兔软骨细胞相对贴壁缓慢,生长滞后。两类软骨细胞随着培养代数的增加,Ⅱ型胶原蛋白的mRNA表达量逐渐减少,ADAMTS5的表达逐代升高,表明随着培养代数的增加,软骨细胞活力逐渐下降。相同代数的大鼠软骨细胞活性较兔软骨细胞更高。甲苯胺蓝染色可见大鼠软骨细胞内成蓝色异染的糖胺多糖成分。不同波段的荧光激发下,Ⅱ型胶原酶免疫荧光染色可见大鼠原代培养的软骨细胞胞浆和胞膜呈清晰的绿色荧光,兔软骨细胞呈红色荧光,细胞核为明亮的蓝色荧光。结论 本实验通过比较大鼠及新西兰兔软骨细胞的培养与特点,证实随培养代数增加,软骨细胞活性逐渐降低,且相同代数大鼠软骨细胞较兔软骨细胞具备更高活性。     

软骨细胞在异体脱细胞软骨基质上的体外培养实验

目的探讨脱细胞软骨基质对软骨细胞体外生长的影响。方法以脱细胞异体兔耳软骨基质为支架材料,以脱细胞异体兔耳软骨膜为对照,体外种植兔耳软骨细胞进行常规培养,观察软骨细胞的生长状况和增殖情况。结果软骨细胞进入脱细胞异体软骨基质构架裸露的空穴,生长旺盛。而在脱细胞异体软骨膜上,软骨细胞不易生长。结论支架材料的表面性状对细胞生长有显著影响,异体脱细胞软骨基质可提供适宜于软骨细胞生长的良好环境,有可能发展成为软骨组织工程的一种天然支架材料。     

Effect of bone morphogenetic proteins 2 and 7 on septal chondrocytes in alginate.

OBJECTIVE: To determine the effects of bone morphogenetic proteins (BMP)-2 and -7, and serum, on extracellular matrix production by human septal chondrocytes in alginate. STUDY DESIGN: Human nasal septal chondrocytes were expanded, suspended in alginate, and cultured in BMP-2 or 7, with and without serum. The optimal concentration of each growth factor was determined based on matrix production. Next, the synergistic effects of BMP-2 and -7 at optimal concentrations were determined on separate beads, based on matrix quantity and histology. RESULTS: Matrix content was highest with concentrations of BMP-2 and -7 of 100 ng/ml and 20 ng/ml, respectively, with serum. Adding both BMP-2 and -7, with serum, increased matrix content by factors of 5.1 versus serum-only cultures, 2.7 versus only BMP-2 with serum, and 2.4 versus only BMP-7 with serum. All comparisons were statistically significant. CONCLUSION: BMP-2 and -7 significantly increase production of extracellular matrix by septal chondrocytes suspended in alginate. The presence of serum improves matrix production. SIGNIFICANCE: BMP-2 and -7 have great potential for use in cartilage tissue engineering.     

Biological freezing of human articular chondrocytes

AIM: To preserve viable, metabolically active chondrocytes cultured in alginate beads at -196 degrees C for further use in in vitro and in vivo studies. METHODS: Human articular chondrocytes were isolated from femoral condyles within 24 h post mortem. To optimize the biological freezing procedure, the chondrocytes were control-rate frozen in different concentrations of dimethyl sulfoxide (DMSO) in Dulbecco's MEM supplemented with 10% FCS before being thawed and the cell viability was determined by Trypan Blue exclusion test. To investigate the effect of control-rate freezing on chondrocyte metabolism, control-rate frozen chondrocytes in 5% DMSO were thawed and cultured in gelled agarose for 2 weeks. Non-frozen chondrocytes cultured in agarose served as controls. Furthermore, human articular chondrocytes were cultured in 2% alginate beads for 2 weeks after which the beads were incubated with 5% DMSO for 0 h, 2.5 h, 5 h and 10 h and frozen at -196 degrees C. Non-frozen alginate beads containing chondrocytes and incubated with 5% DMSO served as a control. After 2 weeks in culture, chondrocytes in agarose or in alginate were sulfated with 10 microCi(35)SO(4)/ml for 48 h. The total production of aggrecans, and the aggrecan subtypes, were subsequently determined. RESULTS: Five percent DMSO in the culture medium was the optimal condition to control-rate freeze and recover viable and functional isolated chondrocytes. Total aggrecan synthesis of control-rate frozen chondrocytes cultured in gelled agarose was not significantly reduced when compared with control cells. The proportion of aggrecan in the aggregate form of control-rate frozen chondrocytes kept in agarose remained unaltered. Chondrocytes, control-rate frozen in the alginate matrix, showed a 0-30% decrease in total aggrecan synthesis rates in culture when compared with the non-frozen chondrocytes. The optimal pre-incubation time of the alginate beads with 5% DMSO was 5 h, without any change in aggrecan synthesis rates when compared with the control situation. Shorter pre-incubation times resulted in an insufficient diffusion of DMSO into the beads and in cell death. There was no difference in the synthesis of the different aggrecan subtypes between frozen and non-frozen chondrocytes in alginate. CONCLUSION: Human articular chondrocytes can be stored at -196 degrees C for 24 h without important decreases in their aggrecan synthesis rates when control-rate frozen as a cell suspension in 5% DMSO. Proportions of the aggrecan subtypes (monomers, aggregates) synthesized by chondrocytes cultured in agarose remained unchanged. The control-rate freezing procedure in the alginate beads pre-incubated with 5% DMSO for 5 h produced no decrease in total aggrecan synthesis rates and no change in the synthesized aggrecan subtypes. Further experiments have to confirm the suitability of this freezing method for long-term storage of chondrocytes allowing us to set up a 'chondrocyte' bank for further use in in vitro and in vivo manipulations.     

软骨细胞在异体脱细胞软骨基质上的体外培养实验

目的 探讨脱细胞软骨基质对软骨细胞全外生长的影响。方法 以脱细胞异体兔耳软骨基质为支架材料，以脱细胞异体兔耳软骨膜为对照。体外种植兔耳软骨细胞进行常规培养，观察软骨细胞的生长状况和增殖情况。结果 软骨细胞进入脱细胞异体软骨基质构架裸露的空穴，生长旺盛。而在脱细胞异体软骨膜上，软骨细胞不易生长。结论支架材料的表面性状对细胞生长有显著影响，异体脱细胞软骨基质可提供适宜于软骨细胞生长的良好环境，有可能发     

软骨细胞在异体脱细胞软骨基质上的体外培养实验

目的探讨脱细胞软骨基质对软骨细胞体外生长的影响。方法以脱细胞异体兔耳软骨基质为支架材料,以脱细胞异体兔耳软骨膜为对照,体外种植兔耳软骨细胞进行常规培养,观察软骨细胞的生长状况和增殖情况。结果软骨细胞进入脱细胞异体软骨基质构架裸露的空穴,生长旺盛。而在脱细胞异体软骨膜上,软骨细胞不易生长。结论支架材料的表面性状对细胞生长有显著影响,异体脱细胞软骨基质可提供适宜于软骨细胞生长的良好环境,有可能发展成为软骨组织工程的一种天然支架材料。     

Monensin stimulation of arylsulfatase B activity in human chondrocytes

Secreted and intracellular arylsulfatase B (ASB) activities were measured in normal and osteoarthritic (OA) human chondrocyte cultures in the absence and presence of monensin, ammonium chloride, and chloroquine. Of the three agents added, only monensin produced a significant stimulation of secreted enzyme activity. Osteoarthritic cells consistently exhibited a three-fold higher level of secreted specific ASB activity than did normal cells, with or without monensin. When compared with normal cells, OA cells also consistently exhibited a twofold heightened intracellular specific enzyme activity both in the absence or presence of monensin. With increasing dosage of monensin, secreted and intracellular ASB activity increased for both OA and normal cells. Total enzyme activity of secreted and intracellular ASB was found to be cell density dependent. No inhibition of secreted or intracellular ASB activity was observed for sparsely plated cultures. In contrast to sparse cultures, an inhibition of secreted ASB, with or without monensin, was observed in densely plated cultures. Intracellular total activity was not inhibited by high-density cultures. Secreted ASB activity was found to be time-dependent after passage. Enzyme activity was maximal at 6 h in both OA and normal cells and decreased by the end of 24 h both in serum-free medium and in serum-free medium with monensin. When compared with normal cells, OA cells expressed higher levels of ASB activity under all test conditions. This heightened activity therefore appears to be a property inherent in the OA chondrocyte.     

小鼠未成熟关节透明软骨细胞的培养与生物学特征研究

目的 建立小鼠未成熟关节透明软骨细胞分离、培养的方法,探讨低氧环境对软骨细胞活性及糖代谢的影响. 方法 机械分离与酶消化相结合,分离、纯化小鼠未成熟关节软骨细胞.分别于低氧( O2体积百分比为 2%)和常氧( O2体积百分比 21%)条件下培养,应用四甲基偶氮唑盐( MTT)法检测细胞活性; RT PCR检测细胞葡萄糖转运体 -1,3及磷酸果糖激酶 mRNA的表达;葡萄糖氧化酶方法测定细胞对葡萄糖的摄取量. 结果Ⅱ型胶原免疫组化和阿利辛蓝染色证实获得细胞为透明软骨细胞.低氧培养环境可提升细胞的增殖能力,诱导细胞表达低氧诱导因子 -1α;伴随低氧诱导因子 -1α的表达及其表达量的提高,葡萄糖转运体 -1,3和磷酸果糖激酶的表达水平升高,细胞对葡萄糖的摄取量增加. 结论 所建立的分离、培养方法可以获得高纯度的透明软骨细胞;软骨细胞可通过氧感应机制以适应低氧环境而调整其代谢和生存状态.