Showing papers by "Edward F. Srour published in 1994"

Human umbilical cord blood hematopoietic progenitor cells: are they the same as their adult bone marrow counterparts?

Abstract: In an attempt to expand the hematopoietic progenitor cell (HPC) content of a single collection of umbilical cord blood (CB), we investigated the ex vivo proliferative potential of CB CD34+ cells and the rate of exit of these cells from G0/G1 phases of cell cycle in response to different cytokine combinations. Initial experiments in which phenotypically defined populations of CB and adult bone marrow (BM) CD34+ cells were examined for their HPC content revealed that, contrary to BM, CB CD34+ human leukocyte A (HLA)-DR+ cells appeared to contain the majority of primitive HPC. In cultures of BM CD34+ HLA-DR+ cells incubated with stem cell factor (SCF)+interleukin-3 (IL-3), CD34+ cells increased five-fold over 5 days, while CD34+ cells from CB CD34+ HLA-DR+ cultures increased 11-fold under these same conditions, illustrating an enhanced proliferative potential of CB CD34+ HLA-DR+ cells vs. similar cells from adult BM. Furthermore, a 6.2-fold increase in the number of CB CD34+ still residing in G0/G1 was observed on day 5 in cultures supplemented with SCF and IL-3, suggesting the generation of large numbers of primitive HPC in vitro. The effect of SCF on the exit of CB and BM CD34+ HLA-DR+ cells from G0/G1 was then examined. Following 36- to 48-hour exposure to SCF, 45% of quiescent CB cells exited G0/G1 in contrast to only 13% of quiescent BM cells. In serum-free media supplemented with either SCF or IL-3 alone, CB CD34+ HLA-DR+ cells did not exit G0/G1 phases of cell cycle as rapidly as when CB plasma was present, unless SCF and IL-3 were added simultaneously. Collectively, these results suggest that CB CD34+ cells are more responsive to cytokine stimulation, especially SCF, and may represent more suitable candidates for ex vivo expansion of HPC than BM cells. Furthermore, these data illustrate potentially important biologic differences between the HPC content of subpopulations of BM and CB cells, and the response of these subpopulations to cytokine stimulation.

A retroviral vector expressing human interferon gamma upregulates MHC antigen expression in human breast cancer and leukemia cell lines.

Abstract: The use of cytokines to modify antigen expression on syngeneic murine tumor cells has led to immunization of the host from subsequent challenges with the parent tumor cell line. To determine whether this approach can be applied to human malignancies we introduced the human interferon gamma gene (IFN gamma) into the human breast cancer cell lines MDA-MB-435 and MDA-MB-231 using retroviral-mediated gene transfer. Retroviral transfer of the IFN gamma gene was associated with decreased growth, decreased tumor invasiveness, IFN gamma production, and upregulation of MHC antigens. While the MDA-MB-435 produced higher levels of IFN gamma than MDA-MB-231, MHC class I and class II antigens were upregulated in both cell lines. Introduction of this vector into the human leukemia cell line K562 led to increased expression of MHC class I antigens, but not class II. Our findings suggest that expression of interferon gamma in breast cancer cells may lead to increased recognition of breast cancer cells by the host immune system. Furthermore, these data suggest that further development of this approach to cancer immunotherapy is warranted.

Drosophila Forkhead Homologues Are Expressed in CD34+/HLA-DR− Primitive Human Hematopoietic Progenitors

Abstract: The Forkhead gene (FKH) regulates morphogenesis in Drosophila. It is the prototype of a new family of transcriptional activators. We used the polymerase chain reaction (PCR) to analyze the expression pattern of this new transcriptional regulatory gene family in primitive hematopoeitic progenitors. Partially degenerate oligonucleotides to two conserved amino acid sequences of this family were used to prime a PCR amplification of cDNA synthesized from CD34+/HLA-DR− hematopoietic cells. Known and novel FKH genes were found to be expressed in these cells.