Endothelial progenitor cells from infantile hemangioma and umbilical cord blood display unique cellular responses to endostatin

Abstract

Infantile hemangiomas are composed of endothelial cells (ECs), endothelial progenitor cells (EPCs), as well as perivascular and hematopoietic cells. Our hypothesis is that hemangioma-derived EPCs (HemEPCs) differentiate into the mature ECs that comprise the major compartment of the tumor. To test this, we isolated EPCs (CD133 ؉ /Ulex europeus-I ؉ ) and mature ECs (CD133 ؊ /Ulex europeus-I ؉ ) from proliferating hemangiomas and used a previously described property of hemangioma-derived ECs (HemECs), enhanced migratory activity in response to the angiogenesis inhibitor endostatin, to determine if HemEPCs share this abnormal behavior. Umbilical cord bloodderived EPCs (cbEPCs) were analyzed in parallel as a normal control. Our results show that HemEPCs, HemECs, and cbEPCs exhibit increased adhesion, migration, and proliferation in response to endostatin. This angiogenic response to endostatin was consistently expressed by HemEPCs over several weeks in culture, whereas HemECs and cbEPCs shifted toward the mature endothelial response to endostatin. Similar mRNAexpression patterns among HemEPCs, HemECs, and cbEPCs, revealed by microarray analyses, provided further indication of an EPC phenotype. This is the first demonstration that human EPCs, isolated from blood or from a proliferating hemangioma, are stimulated by an angiogenesis inhibitor. These findings suggest that EPCs respond differently from mature ECs when exposed to angiogenic or antiangiogenic signals. IntroductionInfantile hemangioma, the most common tumor of infancy, is characterized by rapid proliferation of the endothelial cells followed by slow spontaneous involution. 1 This transition from the proliferating phase to the involuting phase represents a gradient of cellular activity from unregulated proliferation to apoptosis. The molecular events that control the evolution of hemangioma remain obscure. Both intrinsic and extrinsic anomalies have been suggested to underlie the primary defect. [2][3][4][5][6] Recent studies showing that hemangioma-derived endothelial cells (HemECs) are clonal provide support for an intrinsic defect. 4,6 We and others have identified endothelial progenitor cells (EPCs) in hemangioma tissue and circulating blood of patients with hemangiomas, respectively. 7,8 These findings suggest that a hemangioma may arise from the clonal expansion of an EPC.An angioblastic origin for hemangiomas has been envisioned for over a century. In 1863, Virchow 9 questioned whether hemangiomas represented sequestered embryonic mesoderm. Pack and Miller 10 suggested that hemangiomas arise from the localized growth of angioblastic cells. Similarly, Malan 11 imagined hemangiomas as an activation of dormant angioblasts. Histologic examination of hemangioma ECs reveals an immature phenotype with large nuclei and scant cytoplasm. 12 During the rapid growth phase of hemangiomas, syncytial EC hyperplasia, with and without lumens, is seen. In the involuting phase, hyperplasia diminishes and mature vascular channels with defined lumens become prominent. 1 C...

Infantile Hemangiomas: A Disease Model in the Study of Vascular Development, Aberrant Vasculogenesis and Angiogenesis

“…Eventually, the response of cbEPCs to the same experiments shifted to mirror that of mature endothelial cells as the cells were passaged in culture. HemECs exposed to endostatin also demonstrated behavior similar to that of cbEPCs, further demonstrating their abnormal behavior when compared with normal endothelial cells (Khan et al, 2006). Taken together, these data further support the theory that an anomaly intrinsic to the IH gives rise to the lesion.…”

Nucleolin is a receptor that mediates antiangiogenic and antitumor activity of endostatin

“…Moreover, an unexpected phenomenon was observed that hemangioma endothelial cells exhibit similar ES internalization as that of HMECs and HUVECs ( Figure S5I,J), whereas according to the work of Khan et al, ES stimulates rather than inhibits the proliferation of hemangioma endothelial cells. 47 We speculate that the downstream adaptors of NL may not be identical in different cell types. For example, our previous studies show that some isoforms of nonmuscle myosin are involved in the NL signaling in endothelial cells.…”

Rapid Anastomosis of Endothelial Progenitor Cell–Derived Vessels with Host Vasculature Is Promoted by a High Density of Cotransplanted Fibroblasts

“…Since the initial reports of separating EPCs from peripheral blood, 32 circulating EPCs have been isolated with antibodies specific to a variety of cell surface markers, including the progenitor=stem cell marker CD133, 33 the endothelial marker CD34, 32,34,35 CD31, 18,24 or a combination of endothelial and progenitor cell markers. 36 In this study, we purified the endothelial outgrowth of CD31-positive cells from cord blood, but EPCs derived from adult blood have also been shown to have equivalent angiogenic potential when implanted with bone marrow mesenchymal cells. 18,24 The EPC-ECs in our study showed similar morphology and high (relative to HUVECs) in vitro expansion capacity consistent with previous reports.…”