Analysis of growth regulating factors produced by mesenchymal cells of the chick embryo in complete protein-free primary cultures.

在鸡胚胎中，有一群软骨成纤维细胞被称为巩膜成纤维细胞。原代培养的巩膜成纤维细胞分泌多种自分泌生长促进因子，巩膜自分泌因子（scl巩膜自分泌因子，SAFs）到无蛋白培养基中。其中一个因子是SAF-IIa，它是热不稳定的，与肝素结合，在小鼠成纤维细胞系BALB/c 3T3 A31细胞上显示出很强的DNA合成促进活性，经凝胶过滤分子量约为16kDa。这些数据表明SAF-IIa与FGF家族的生长因子有关。然而，肝素增强对促生长活性的影响表明，当对巩膜成纤维细胞和BALB/c 3T3 A31细胞进行检测时，SAF-IIa与aFGF或bFGF并不相同。另一种热不稳定的自分泌促生长因子SAF-IIb与肝素结合较弱，对BALB/c 3T3 A31细胞无促生长活性。耐热生长因子saf - 1能有效促进BALB/c 3T3细胞的增殖，热处理后其活性增强。全胚成纤维细胞在无蛋白培养基中表现出低自分泌生长，主要产生类似saf - iia的促生长活性，而不产生SAF-I。这表明，体外培养的巩膜成纤维细胞的强增殖活性可归因于生长阶段产生的一种强而稳定的自分泌因子saf - 1，这是巩膜软骨细胞的一种特殊特性。

In the chick embryo, there is a population of chondrogenic fibroblasts known as scleral fibroblasts. Scleral fibroblasts in primary culture secrete multiple autocrine growth-promoting factors, scleral autocrine factors (SAFs), into protein-free medium. One such factor, SAF-IIa, which is heat-labile and binds to heparin, shows strong DNA synthesis-promoting activity on the mouse fibroblast cell line, BALB/c 3T3 A31 cells and has a molecular weight of ca. 16kDa by gel filtration. These data suggest that SAF-IIa is related to growth factors of the FGF family. However, the effects of heparin augumentation on the growth-promoting activity suggest that SAF-IIa is not identical to aFGF or bFGF, when assayd on scleral fibroblasts and also on BALB/c 3T3 A31 cells. The other heat-labile autocrine growth-promoting factor, SAF-IIb, shows weak binding to heparin and no growth-promoting activity for BALB/c 3T3 A31 cells. The heatresistant growth factor, SAF-I, is effective in enhancing the proliferation of BALB/c 3T3 cells and its activity is increased by heat treatment. Whole-embryo fibroblasts, which show low autocrine growth in protein-free medium, produce mainly SAF-IIa-like growth-promoting activity and do not produce SAF-I.This indicates that the strong proliferative activity of scleral fibroblasts in vitro can be attributed to the production of a strong and stable autocrine factor, SAF-I, in the growing phase and is a specialized property of the chondrogenic cells of the sclera.