Growth factors produced by human embryonic kidney cells that influence megakaryopoiesis include erythropoietin, interleukin 6, and transforming growth factor‐beta

Abstract

Partially purified protein preparations containing megakaryocyte growth factor activity were prepared from human embryonic kidney (HEK) cell conditioned medium using ammonium sulfate precipitation, Cibicron blue affinity chromatography, and wheatgerm lectin affinity chromatography. Treatment of these preparations with neutralizing antibodies directed against erythropoietin (EPO) and interleukin 6 (IL6) resulted in a dramatic reduction in their capacity to stimulate megakaryocyte maturation in vitro. The presence of EPO in these preparations was confirmed by both immunoblotting and use of a mouse spleen erythroid progenitor cell proliferation assay routinely used to quantitate EPO activity in vitro. Northern blot analysis of HEK cell-derived mRNA with IL6 DNA probes revealed the presence of an IL6 transcript with a molecular size of 1.3 kb. Analysis of the HEK cell-derived preparation by ELISA confirmed the presence of immunologically reactive IL6. In addition, it was shown that purified recombinant human EPO and IL6 stimulated megakaryocyte maturation in the in vitro assay used in this study. These data indicate that the activity in HEK cell conditioned medium that stimulates megakaryocyte maturation in vitro is predominantly due to the presence of IL6 and EPO. Immunoneutralization studies of another HEK cell-derived preparation, which was inhibitory in the megakaryocyte maturation assay, demonstrated that it contained transforming growth factor beta (TGF beta), a potent inhibitor of megakaryocyte maturation. Taken together, these studies indicate that HEK cell conditioned medium, which has previously been reported to contain megakaryocyte growth factor activity, is comprised of a complex mixture of growth and differentiation factors, some of which promote and others that inhibit the process of megakaryopoiesis.

Infusion of human embryonic kidney cell line conditioned medium reverses kainic acid induced hippocampal damage in mice

“…In the present study, we observed that infusion of HEK cells or HEK-CM enhanced the endogenous mRNA level of EPO in the host brain. A previous study demonstrating the presence of EPO in HEK-CM and its role in megakaryopoiesis supports our findings [11]. EPO exerts its neuroprotective action by activating intracellular cell survival pathways such as the PI3K/Akt pathway that ultimately activates the anti-apoptotic factors, including Bcl-2 [15].…”

“…Nonetheless, the recent consensus is that the host tissue regeneration may be partly attributed to the paracrine effects of transplanted cells, which in turn activate the host's endogenous reparative mechanisms for cellular and functional recovery [8e10]. In this context, conditioned media (CM) derived from cell cultures are excellent sources of neurotrophic factors and cytokines [11,12]. Though the majority of studies investigated the effects of cell transplantation in animal models of hippocampal neurodegeneration [6,7], there is not much information available on the effects of CM per se in cellular and behavioral recovery after hippocampal damage.…”

“…Interestingly, a recent study reported by the research group that introduced the HEK cell line to the scientific community demonstrated that this particular cell line also contains a small population of neurons [14]. Furthermore, the CM derived from HEK cells (HEK-CM) could potentiate megakaryopoiesis caused by the presence of erythropoietin (EPO) and other cytokines [11]. Because EPO is a known neuroprotectant [15,16], we hypothesized that infusion of HEK cells or HEK-CM might protect hippocampal neurons against kainic acid (KA)-induced excitotoxicity.…”

Bone Marrow Phospho-STAT5 Expression in Non-CML Chronic Myeloproliferative Disorders Correlates With JAK2 V617F Mutation and Provides Evidence of In Vivo JAK2 Activation

“…It has been shown that megakaryocytes do indeed respond to growth factors or contain receptors for them. 15,34 In practice, this scenario (misinterpreting nMEG pSTAT5 immunoreactivity because of growth factors for a JAK2 V617F+ CMPD) is unlikely to represent a diagnostic problem, because suspected CMPD patients are not usually treated with growth factor therapies. Furthermore, a careful clinical history would easily resolve the matter.…”

Cytokines in the Differentiation Therapy of Leukemia: From Laboratory Investigations to Clinical Applications

“…43 Unlike IL-5, which is eosinophil-specific, IL-6 influences the proliferation of multipotent myeloid progenitor cells, and also stimulates human megakaryocyte maturation and differentiation in vitro. 44,45 EPO and TPO are two lineage-specific hematopoietic growth factors that are produced primarily by the kidney 46 and liver, 47 respectively. EPO regulates erythrocyte production while TPO functions to regulate platelet production.…”