Establishment of clonal preadipose cell line from bovine adipose tissue

有关前脂肪细胞增殖分化的信息将有助于控制肉牛的脂肪沉积。本研究试图从牛脂肪组织中建立前体脂肪细胞克隆细胞系。此外，利用原代培养系统研究了某些营养素或合成化合物对牛前脂肪细胞的成脂或抗成脂作用。由于这些未成熟的组织将保留许多未分化的前脂肪细胞，因此采用几种小牛脂肪组织和成年牛肌肉内脂肪组织作为细胞来源进行克隆。采用差示胰酶消化法和差示细胞粘附法选择性回收前脂肪细胞。在原代培养中，胎牛血清的存在阻碍了牛前脂肪细胞的脂肪转化。维生素C在无血清条件下促进脂肪细胞分化。小鼠过氧化物酶体增殖物激活受体(PPAR)γ的人工配体--噻唑烷二酮在原代培养中能有效地诱导牛前脂肪细胞向脂肪细胞分化。维甲酸阻断了这一作用。这些结果提示牛前脂肪细胞中存在功能性的PPAR和维甲酸受体。此外，这些体外观察表明，维生素A在体内通常会抑制肉牛脂肪组织中的脂肪细胞分化，低维生素A状态可能有利于脂肪细胞的分化，从而促进牛肉大理石纹的发展。然而，出于经济和伦理方面的原因，不建议对商业肉牛施加这种营养压力。通过阐明牛肌肉组织中脂肪细胞分化的机制，可以建立更可靠和更可接受的生产高大理石纹牛肉的方法。

The information on the proliferation and differentiation of preadipocyte would be useful for the control of fat deposition in beef cattle. We have tried in the present study to establish a clonal cell line of preadipocyte from bovine adipose tissue. In addition, adipogenic or antiadipogenic effect of some nutrients or synthetic compounds on bovine preadipocytes were investigated using primary culture system.Several adipose tissues from calves and intramuscular adipose tissues from adult cattle were used as sources of cells to be cloned because such immature tissues would retain many undifferentiated preadipose cells. Differential trypsinization method and differential cell adhesion method were adopted for selective recovery of preadipocytes. However, we could not find any available clones which maintain preadipose phenotype for generations.In primary culture, the presence of fetal calf serum in culture medium prevented adipose conversion of bovine preadipocytes. Vitamin C accelerated adipocyte differentiation in serum-free condition. A thiazolidinedione, which is an artificial ligand for murine peroxisome proliferator-activated receptor (PPAR) gamma, powerfully induced adipocyte differentiation of bovine preadipocytes in primary culture. Retinoids blocked this effect. These results suggest the presence of functional PPAR and retinoid receptor in bovine preadipocyte. In addition, these in vitro observations imply that vitamin A usually suppresses adipocyte differentiation in adipose tissue of beef cattle in vivo and that low vitamin A status may favor adipocyte differentiation and thus the development of beef marbling. However, such nutritional stress on commercial beef cattle would not be recommended for economical and ethical reasons. More reliable and acceptable methods for producing highly marbled beef are to be established, which could be achieved through the clarification of the mechanism of adipocyte differentiation in bovine muscle tissue.