{'fraction_non_alphanumeric': 0.03058103975535168, 'fraction_numerical': 0.011467889908256881, 'mean_word_length': 4.409090909090909, 'pattern_counts': {'":': 0, '<': 4, '<?xml version=': 0, '>': 2, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Bone Marrow Endothelial Cell-Derived Factors Inhibit the Growth of Marrow CFU-F.

The present study investigated the effects of the serum-free conditioned media of the bone marrow endothelial cells on CFU-F for potential mechanisms upon which hematopoiesis may be regulated by them within the bone marrow microenvironment. After obtaining the serum-free conditioned media of human and murine purified bone marrow endothelial cells (hBMEC-CM and mBMEC-CM) in vitro, MW > 10 kD, 3 - 10 kD and < 3 kD components were sifted out from these media by means of serial ultrafiltration. Assays of CFU-F were performed to test the effects of BMEC-CM and their ultrafiltrated components. The results showed that every one of hBMEC-CM, mBMEC-CM and their MW < 3 kD components exerted a suppressive effect on the proliferation of corresponding CFU-F but MW > 10 kD and 3 - 10 kD components. The BMEC-CM and MW < 3 kD components decreased the number as well as the size of CFU-F. There were the markedly negative concentration-dependent relations between the concentrations of MW < 3 kD component and the numbers of CFU-F. These findings suggested that bone marrow endothelial cells in culture could secrete at least a humoral factor (molecular weight less than 3 kD) which has an inhibitory effect on the growth of CFU-F.