Effect of recombinant stem cell factor on clonogenic maturation and cycle status of human fetal hematopoietic progenitors

SCF increases in utero-labeled stem cells migration and improves wound healing

Diabetic skin wounds lack the ability to heal properly and constitute a major and significant complication of diabetes. Nontraumatic lower extremity amputations are the number one complication of diabetic skin wounds. The complexity of their pathophysiology requires an intervention at many levels to enhance healing and wound closure. Stem cells are a promising treatment for diabetic skin wounds as they have the ability to correct abnormal healing. Stem cell factor (SCF), a chemokine expressed in the skin, can induce stem cells migration, however the role of SCF in diabetic skin wound healing is still unknown. We hypothesize that SCF would correct the impairment and promote the healing of diabetic skin wounds. Our results show that SCF improved wound closure in diabetic mice and increased HIF-1α and vascular endothelial growth factor (VEGF) expression levels in these wounds. SCF treatment also enhanced the migration of red fluorescent protein (RFP)-labeled skin stem cells via in utero intra-amniotic injection of lenti-RFP at E8. Interestingly these RFP+ cells are present in the epidermis, stain negative for K15, and appear to be distinct from the already known hair follicle stem cells. These results demonstrate that SCF improves diabetic wound healing in part by increasing the recruitment of a unique stem cell population present in the skin.

In vitro proliferation and differentiation of erythroid progenitors of cord blood

Stem cell factor (SCF) is known to synergize with erythropoietin (EPO) for erythropoiesis in vitro. Clonogenic assay and suspension culture were used to assess the effect of EPO alone or its combination with SCF on the proliferation and differentiation of erythroid progenitors of cord blood. Colony formation, increase in cell count, and cell cycling status for the proliferation as well as expression of Glycophorin A (Gly A) and hemoglobinization as the marker of differentiation were determined with each stimulation. The cell cycle status of the cells in suspension cultures was determined using FACScan after labeling of cells with propidium iodide. Expression of Gly A and degree of hemoglobinization were determined by FACScan and spectrophotometer on the cells plucked from colonies in semisolid culture. Larger increases in cell counts in suspension culture were observed with EPO + SCF after 12 days of inoculation than with EPO alone. Mean doubling time was 14.2 h with EPO + SCF and 22.7 h with EPO alone. The proportion of cells in S and G2 + M phase in day 14 suspension culture was 48% with EPO + SCF and 43% with EPO alone (no significant difference). Mean colony counts per 10(5) nonadherent mononuclear cells were 76 +/- 14 with EPO + SCF and 51 +/- 15 with EPO at day 14 (p < 0.05). The number of macroscopic colonies with > 0.5 mm diameter was 10.7 +/- 1.2 with EPO + SCF and 0.3 +/- 0.5 with EPO (p < 0.05). Percent of Gly A+ cells was 75% for both EPO + SCF and EPO colonies at day 14. Hemoglobin concentration/10(5) cells at day 14 was 0.70 +/- 0.17 microgram with EPO + SCF, and 1.16 +/- 0.32 micrograms with EPO alone (p < 0.05). In conclusion, SCF in the combination with EPO showed a synergistic effect for erythroid proliferation in colony number as well as colony size derived from cord blood, while SCF with EPO decreased hemoglobin synthesis but not Gly A expression at day 14.

Synergistic response of cord blood myeloid progenitor cells to the combined administration of human granulocyte colony-stimulating factor and human stem cell factor in vitro

We compared the in vitro response of myeloid progenitor cells [colony-forming units of culture (CFU-C)] that were prepared from human umbilical cord blood to the administration of the combination of granulocyte colony-stimulating factor (G-CSF) and stem cell factor (SCF) versus that of CFU-C obtained from normal human bone marrow. Progenitors were purified according to CD34 expression; the number and size of colonies were evaluated by culture in agar or methylcellulose, respectively. In the presence of G-CSF alone, the mean number of colonies was significantly greater in the bone marrow culture versus that of cord blood. SCF alone bad little effect on colony formation, but in the presence of optimal or suboptimal concentrations of G-CSF, SCF significantly increased colony formation from both cell sources. Its effect on cord blood significantly exceeded that on bone marrow. SCF used in combination with G-CSF significantly increased the size of the colonies with cord blood CFU-C; this effect was less marked with bone marrow CFU-C. The percentage of cells that expressed c-Kit, the SCF receptor, did not appear to differ between the two sources of CFU-C. Results indicate that cord blood CFU-C showed a greater response to SCF in combination with G-CSF than did bone marrow CFU-C.

Hodgkin's Disease and Anaplastic Large Cell Lymphoma Revisited. 1. unique cytokine and cytokine receptor profile distinguished from that of non-hodgkin's lymphomas

In cultures, and in tissues as well, Hodgkin's and Reed-Sternberg (H-RS) cells and anaplastic large cell lymphoma (ALCL) cells are known to express a variety of cytokines, including IL-1, -5, -6, -8, -9, TNF-alpha, GM-CSF, M-CSF, TGF-beta, CD70, CD80, and CD86. Various numbers of H-RS/ALCL cells may express cytokine receptors (R), such as CD30, CD40, IL-2R (CD25/CD122), IL-6R (CD126), IL-7R (CD127), TNF-R (CD120), TGF-beta-R (CD 105/endoglin), M-CSF-R (CD115), and SCF-R (CD117/c-kit receptor). All of these cytokines and cytokine receptors are implicated in the growth regulation of H-RS/ALCL cells, the histopathologic alterations in tissues, and the clinical manifestations in patients with Hodgkin's disease (HD) or ALCL. Many of these cytokines or cytokine receptors also play an important role in the pathogenesis of other types of lymphomas. In this review, we describe the cytokine or cytokine-receptor expression that is diacritic for H-RS/ALCL cells. The identification of such unique cytokine-cytokine receptor interactions is likely to explain the biologic property that distinguishes HD/ALCL from other types of lymphomas. These interactions include those of CD30L-CD30, CD40L-CD40, CD70-CD27, CD80/CD86- CD28, SCF-CD117, IL-9-IL-9R, and IL-7-IL-7R. The H-RS/ALCL cells express IL-9 and two cytokine receptors, CD30 and CD117, which are observed infrequently in NHLs. Although IL-7 expression is not restricted to H-RS/ALCL cells, the expression of IL-7 in conjunction with IL-9 and/or CD117 may be regarded as unique for HD/ALCL because of an unusual combination and a synergistic activity among these cytokines. The expression of CD70 and CD80/CD86 (as cytokines) may exert a unique effect in HD because of intimate contact between H-RS cells and CD27/CD28-positive T cells. The expression of these costimulators (CD70 and CD80/CD86) and other adhesion/constimulator molecules such as CD54 and CD58, along with the secretion of soluble cytokines such as IL-1, IL-6, IL-7, or TNFs by H-RS/ALCL cells, could result in the profound T-cell proliferation often seen in lymph nodes involved by HD and some ALCL. On the other hand, the expression of CD30L and CD40L by surrounding T cells may affect the proliferation of H-RS/ALCL cells. The cytokine-cytokine receptor interaction between H-RS cells and T cells via direct cell-cell contact is bidirectional, a situation not commonly seen in NHLs. Copyright 1995 S. Karger AG, Basel