Positive and negative haematopoietic cytokines produced by bone marrow endothelial cells

Recently, cytokines and interleukins such as SCF, GM-CSF, G-CSF, TGF-beta, IL-6, IL-7, IL-8, IL-11 have been reported to be elaborated by endothelial cells. For further study, serum free bone marrow endothelial cell condition ed medium (BMEC-CM) was collected and ultrafiltrated by using a centriprep 10. The concentrated retentate (R-BMEC-CM) contained some substances whose molecular weight was more than 10 000 daltons. The filtrate (F-BMEC-CM) con tained some substances whose molecular weight was less than 10 000 daltons. The effects of R-BMEC-CM and F-BMEC-CM on the growth of haematopoietic pro genitors and the expression of cytokine and interleukin mRNAs of BMEC were investigated. The results showed that R-BMEC-CM stimulated the growth of CF U-GM, HPP-CFC, BFU-E, CFU-E, and CFU-Meg; while F-BMEC-CM inhibited the gro wth of these progenitors. Using the method of hybridizing to the Atlas cDNA Array, we were able to detect the presence of mRNAs of cytokines and inter leukins in bone marrow endothelial cells. Our finding of the existence of m RNAs of SCF, GM-CSF, IL-6, TGF-beta, IL-1, and IL-11 in these cells was in agreement with the data reported previously. Furthermore, we detected mRNAs of MIP-2, Thymosion-beta 4, PDGF, MSP-1, IFN-gamma, IL-13 and inhibin, whi ch are related to haematopoiesis. Among these cytokines and interleukins, S CF, GM-CSF, IL-6, IL-1, and IL-11 are haematopoietic stimulators which may be responsible for the stimulative effects on the growth of haematopoietic progenitors. One of our new findings, the thymosin-beta 4, is a small molec ular haematopoietic inhibitor. It may be responsible for the inhibitory eff ect of F-BMEC-CM on haematopoietic progenitors. The presence of mRNAs of BM P, MSP-1, MIP-2, PDGF and IL-13 suggests that bone marrow endothelial cells might elaborate these substances. Their influence on haematopoietic progen itors needs further study. (C) 2000 Academic Press.