CONSTRUCTION OF TEMPERATURE AND ZN-DEPENDENT HUMAN STROMAL CELL-LINESTHAT AMPLIFY HEMATOPOIETIC PRECURSORS FROM CORD-BLOOD CD34(+) CELLS

Forty-five human stromal cell lines were established from long-term bo ne marrow cultures transformed with a new vector, pNu MTSVts, which co ntains the Zn-inducible metallothionein promoter and the temperature-d ependent SV40 T antigen from SV40 A58 mutant. Six of these cell Lines were studied because of their growth capacity. All cell lines differed with respect to growth potential, expression of cell surface markers, and cytokine transcripts. Major histocompatibility complex (MHC) clas s I, CD29, CD49d, and CD51 were present on all stromal cell lines, MHC class II and CD34 were consistently absent, and CD11a (LFA-1), CD18 ( ICAM-1R), CD54 (ICAM-1), CD58 (LFA-3) CD56 (N-CAM), CD106 (V-CAM), lam inin, and collagen IV were diversely expressed. All cell lines contain ed interleukin (IL)-1 alpha, IL-1 beta, IL-2, IL-5, and macrophage col ony-stimulating factor (M-CSF) transcripts, whereas granulocyte M-CSF, TNF alpha, IL-3, IL-4, and IL-7 were diversely expressed. The most ch aracteristic feature of these cells was their varying capacity to expa nd cord blood CD34(+) cells. One of these stromal cell lines ensured m ore than twofold expansion of the initial CD34(+)CD10(-)CD19(-) popula tion in the first 2 weeks. Differentiation toward the B cell lineage w as limited, producing only very small numbers of CD19(+) cells after 6 weeks of culture.