Indiana University

David A Ingram

Mervin C Yoder

D Wade Clapp

Feng-Chun Yang

A hierarchy of endothelial colony forming cells (EPCs) was identified from mammalian cord blood, umbilical vein and aorta. A newly isolated cell named high proliferative potential&#x2014;endothelial colony forming cell (HPP-ECFC) was isolated and characterized. Single cell assays were developed that test the proliferative and clonogenic potential of endothelial cells derived from cord blood, or from HUVECs and HAECs. EPCs were found to reside in vessel walls. Use of a feeder layer of cells derived from high proliferative potential-endothelial colony forming cells (HPP-ECPCS) from human umbilical cord blood, stimulates growth and survival of repopulating hematopoietic stem and progenitor cells. Stimulation of growth and survival was determined by increased numbers of progenitor cells in in vitro cultures and increased levels of human cell engraftment in the NOD/SCID immunodeficient mouse transplant system.

Isolation, expansion and use of clonogenic endothelial progenitor cells

A hierarchy of endothelial colony forming cells (EPCs) was identified from mammalian cord blood, umbilical vein and aorta. A newly isolated cell named high proliferative potential-endothelial colony forming cell (HPP-ECFC) was isolated and characterized. Single cell assays were developed that test the proliferative and clonogenic potential of endothelial cells derived from cord blood, or from HUVECs and HAECs. EPCs were found to reside in vessel walls. Use of a feeder layer of cells derived from high proliferative potential-endothelial colony forming cells (HPP-ECPCS) from human umbilical cord blood, stimulates growth and survival of repopulating hematopoietic stem and progenitor cells. Stimulation of growth and survival was determined by increased numbers of progenitor cells in in vitro cultures and increased levels of human cell engraftment in the NOD/SCID immunodeficient mouse transplant system.

Germline mutations in the NF1 tumor suppressor gene cause Von Recklinghausen's neurofibromatosis type 1 (NF1), a common genetic disorder of the nervous system characterized by plexiform neurofibroma development. Using adoptive transfer of hematopoietic cells, we establish that NF1 heterozygosity of bone marrow derived cells in the tumor microenvironment is sufficient to allow neurofibroma progression in the context of Schwann cell nullizygosity. Further, genetic or pharmacologic attenuation of the c-kit signaling pathway in hematopoietic cells greatly diminishes neurofibroma initiation and progression. These studies identify haploinsufficient hematopoietic cells and the c-kit receptor as therapeutic targets for preventing plexiform neurofibromas and implicate mast cells as critical mediators of tumor initiation. Administering therapeutically effective doses of a tyrosine kinase inhibitor such as the compound imatinib mesylate to a patient in need thereof to treat tumors in a human patient afflicted with plexiform neurofibroma.

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Indianapolis, IN, United States of America

David A Ingram