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The 11 th International Workshop on KSHV & Related Agents, Birmingham, UK
Poster Session Abstract P5
ENDOTHELIAL PROGENITORS FROM THE PERIPHERAL BLOOD OF PATIENTS
WITH CLASSIC KAPOSI’S SARCOMA ARE PERSISTENTLY INFECTED BY KSHV
Taddeo A 1 , Della Bella S, 1 Colombo E, 1 Brambilla L, 2 Bergamo E, 3 Calabrò ML. 3
1Laboratory of Immunology, Dipartimento di Scienze e Tecnologie Biomediche, Università
degli Studi di Milano; 2 Departiment di Dermatology, IRCCS Ospedale Maggiore,
Milano; 3 Immunology and Diagnostic Molecular Oncology, Istituto Oncologico Veneto,
IRCCS, Padova, Italy.
Abstract
Accumulating evidence indicates that tumor angiogenesis is supported by the
mobilization and incorporation of endothelial progenitor cells (EPCs), highly proliferative
precursors of bone marrow origin. Our recent demonstration that EPCs are increased in
the peripheral blood of patients with Kaposi’s sarcoma (KS), together with the intrinsic
biologic properties of these cells, strongly suggests that EPCs could be involved in the
pathogenesis of KS. The fact that the characteristic spindle cells share many markers
with vascular endothelial cells and are thought to be of endothelial origin further supports
this hypothesis. A possible scenario may be that EPCs may act as preferential KSHV
reservoirs and, whether infected, may home to permissive sites and propagate to
produce KS lesions. Novel insights into the state of KSHV infection of EPCs could greatly
improve the comprehension of KS pathogenesis. Therefore, we investigated KSHV
infection of ex-vivo cultured late-EPCs that, among other cell populations with endothelial
features, contribute more directly to neovascularization and might represent a major
source of endothelial progenitors in vivo. We found that late-EPCs from KS patients
harbor KSHV DNA and retain the virus after multiple passages. Lytic phase induction or
hypoxia could amplify the virus in cells and supernatants, indicating that late-EPCs
support KSHV productive replication. EPCs appear therefore to represent potential virus
reservoirs and putative precursors of KS spindle cells. The biological mechanisms that
govern the infection of EPC by KSHV are currently under investigation.
Presenting author Email: lcalabro@unipd.it
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