A simple labeling procedure of stem/progenitor cells based on the use of Gd-HPDO3A and Eu-HPDO3A, respectively, is described. The Gd-chelate acts as
Ex vivo expanded endothelial progenitor cells (EPCs) represent a new potential approach for the revascularization of ischemic sites. However, local accumulation of infused EPCs in these sites is poor, and the mechanisms responsible for their homing are largely unknown. We observed the expression of L-selectin, an adhesion receptor that regulates lymphocyte homing and leukocyte rolling and migration, on ex vivo expanded blood-derived human EPCs. When EPCs were subcloned in SV40-T large Ag-transfected isolates, the copresence of L-selectin and endothelial lineage markers was confirmed. We therefore demonstrated that the expression of L-selectin by EPCs was functional because it mediates interaction with a murine endothelial cell line (H.end) expressing L-selectin ligands by way of transfection with α(1,3/4)-fucosyltransferase. Indeed, adhesion of EPCs after incubation at 4°C on a rotating platform was enhanced on α(1,3/4)-fucosyltransferase-transfected H.end cells compared with control vector-transfected cells, and treatment with anti-L-selectin Abs prevented this event. We then studied the role of L-selectin in EPC homing in vivo. H.end cells were implanted s.c. in SCID mice to form endothelioma tumors, and EPCs were subsequently i.v. injected. L-selectin+ EPCs localized into α(1,3/4)-fucosyltransferase-transfected endothelial tumors to a greater extent than in control tumors, and they were able to directly contribute to tumor vascularization by forming L-selectin+ EPC-containing vessels. In conclusion, our results showed that a mechanism typical of leukocyte adhesion is involved in the vascular homing of EPCs within sites of selectin ligand expression. This observation may provide knowledge about the substrate to design strategies to improve EPC localization in damaged tissues.
Extracranial spread of neuroectodermal tumors is an unusual event, most frequently expected from glioblastomas and medulloblastomas. Single cases of metastatic oligodendrogliomas have been described, but no genetic data are reported. Oligodendrogliomas are characterized by distinct genetic alterations, i.e. loss of heterozygosity (LOH) of 1p and 19q; therefore, molecular genetic analysis of metastatic cases is of considerable interest. It may be instrumental in defining the distant tumor as metastatic oligodendroglioma and give clues to the genetic events associated with the highly malignant transformation. We present the case of a patient with multiple bone metastases from a cerebral oligodendroglioma. Oligodendroglioma grade II was the diagnosis both at original and second operation, performed 7 and 1 years before the extracranial dissemination. The extraneural spread presented before the local intracranial recurrence. The patient received procarbazine, lomustine, vincristine chemotherapy and radiotherapy after the second surgery. The computed tomography-guided biopsy of the bone lesions revealed tumor cells positive for GFAP, S-100 and Leu-7 and negative for cytokeratin, LCA and EMA. The genetic analysis of DNA from the original tumor, the bone metastasis and the autoptic brain tumor showed LOH of 1p; heterozygous deletion of CDKN2A/p 16 was detected as additional alteration in the metastasis and in the intracranial tumor at autopsy. TP53, MDM2 and CDKN2A/p14ARF genes were unchanged. Repeated brain surgery and extended survival may have acted as promoter of extraneural dissemination. Loss of CDKN2A most probably played an important role in the malignant progression: its involvement in metastatic potential remains to be clarified. Our data confirm that malignant transformation of oliogodendrogliomas may be undetected by histology and underscore the importance of genetic analysis. Coincidentally with intensive anticancer therapy, chemotherapy included, employed in patients with oligodendroglioma and the ensuing long survival, the frequency of metastatic oliogodendrogliomas may increase.
In adult medulloblastoma, postoperative radiotherapy is significantly effective in prolonging time to recurrence and survival time; however, the response of individual cases to radiotherapy, that is the total survival, is different. Apoptosis is an important cellular response to radiation. It can be hypothesized that the individual radiosensitivity of medulloblastomas depends on the individual capability to undergo apoptosis. p53 protein is involved in the apoptotic response to ionizing radiation; loss of function of p53 can be the consequence not only of TP53 mutations, but also of amplification and/or overexpression of the MDM2 gene. We have analyzed cerebellar medulloblastomas from 51 adults (>16 years of age) for MDM2 gene amplification (by differential polymerase chain reaction assay), TP53 gene mutation (by polymerase chain reaction single-strand conformation polymorphism analysis of exons 5-8), and immunohistochemical expression of p53 (clone DO1) and MDM2 (clone IF2). The results have been evaluated in relation to age, tumor location, classic or desmoplastic type, MIB-1 labeling index, and total survival. No tumor had MDM2 amplification. Ten tumors had MDM2 positive tumor cells. One case had a mutated TP53 gene; 16/51 cases had intense p53 immunostaining. Only 2 MDM2 protein-positive tumors were also p53-positive. Both subgroups of MDM2 - and p53-positive tumors had a significantly shorter postoperative survival. In conclusion, the overexpression of MDM2 protein and the accumulation of wild-type p53 are unrelated in adult medulloblastoma; they may result in a reduced apoptotic response after radiotherapy and contribute to a shortened survival. Also, MDM2 amplification and TP53 gene mutation are rare events in medulloblastomas of adults.
In adult medulloblastoma, postoperative radiotherapy is significantly effective in prolonging time to recurrence and survival time; however, the response of individual cases to radiotherapy, that is the total survival, is different. Apoptosis is an important cellular response to radiation. It can be hypothesized that the individual radiosensitivity of medulloblastomas depends on the individual capability to undergo apoptosis. p53 protein is involved in the apoptotic response to ionizing radiation; loss of function of p53 can be the consequence not only of TP53 mutations, but also of amplification and/or overexpression of the MDM2 gene. We have analyzed cerebellar medulloblastomas from 51 adults (>16 years of age) for MDM2 gene amplification (by differential polymerase chain reaction assay), TP53 gene mutation (by polymerase chain reaction single-strand conformation polymorphism analysis of exons 5-8), and immunohistochemical expression of p53 (clone DO1) and MDM2 (clone IF2). The results have been evaluated in relation to age, tumor location, classic or desmoplastic type, MIB-1 labeling index, and total survival. No tumor had MDM2 amplification. Ten tumors had MDM2 positive tumor cells. One case had a mutated TP53 gene; 16/51 cases had intense p53 immunostaining. Only 2 MDM2 protein-positive tumors were also p53-positive. Both subgroups of MDM2 - and p53-positive tumors had a significantly shorter postoperative survival. In conclusion, the overexpression of MDM2 protein and the accumulation of wild-type p53 are unrelated in adult medulloblastoma; they may result in a reduced apoptotic response after radiotherapy and contribute to a shortened survival. Also, MDM2 amplification and TP53 gene mutation are rare events in medulloblastomas of adults.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.