Shyam Bhakta

Promise of New Vascular-Disrupting Agents Balanced With Cardiac Toxicity: Is It Time for Oncologists to Get to Know Their Cardiologists?

Willem J. van Heeckeren, Division of Hematology/Oncology, Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH Shyam Bhakta and Jose Ortiz, Division of Cardiology, Department of Medicine, CASE School of Medicine, Cleveland, OH Jeff Duerk, Departments of Radiology and Biomedical Engineering, CASE School of Medicine, Cleveland, OH Matthew M. Cooney, Afshin Dowlati, Keith McCrae, and Scot C. Remick, Division of Hematology/Oncology, Department of Medicine, Case Western Reserve University School of Medicine, Developmental Therapeutics Program, CASE Comprehensive Cancer Center, University Hospitals of Cleveland, Cleveland, OH

Umbilical cord blood-selected CD133+ cells exhibit vasculogenic functionality in vitro and in vivo

BACKGROUND AIMS Current clinical trials utilize non-selected bone marrow (BM) mononuclear cells (MNC) to augment vasculo genesis within ischemic vascular beds. Recent reports have identified a diminished number and function of hemat-opoietic stem cells (HSC) from aged and diseased patients. Umbilical cord blood (UCB) provides a potential robust allo-geneic source of HSC for therapeutic vasculogenesis. METHODS MNC and magnetically isolated CD133(+) cells were assessed for viability (trypan blue) and surface phenotype (flow cytometry). To test in vivo functionality of the cells, NOD/SCID mice underwent ligation of the right femoral artery followed immediately by cell injection. Blood flow recovery, necrosis, BM engraftment of human cells and histologic capillary density were determined. Cells were tested for potential mechanisms mediating the in vivo effects, including migration, cytokine secretion and angiogenic augmentation (Matrigel assays). RESULTS Surface expression analysis showed CD31 (PECAM) expression was greatly increased in UCB CD133(+) cells compared with BM MNC. At 28 days, perfusion ratios were highest in animals receiving UCB CD133(+) cells, while animals receiving BM CD133(+) cells and BM MNC demonstrated perfusion ratios statistically higher than in animals treated with cytokine media alone. Animals receiving CD133(+) cells showed a statistically higher capillary density, reduced severe digit necrosis and increased engraftment in the BM than animals treated with unselected BM MNC. In vitro studies showed equivalent migration to stromal-derived factor-1 (SDF-1), increased production of tumor necrosis factor alpha (TNF-alpha) and increased branch points with the co-incubation of CD133(+) cells with human umbilical vein endothelial cells (HUVEC) in the Matrigel angiogenesis assay. CONCLUSIONS Taken together, UCB CD133(+) cells exhibit robust vasculogenic functionality compared with BM MNC in response to ischemia.

Myocardial Stunning Following Combined Modality Combretastatin-Based Chemotherapy: Two Case Reports and Review of the Literature

Myocardial stunning, known as stress cardiomyopathy, broken‐heart syndrome, transient left ventricular apical ballooning, and Takotsubo cardiomyopathy, has been reported after many extracardiac stressors, but not following chemotherapy. We report 2 cases with characteristic electrocardiographic and echocardiographic features following combined modality therapy with combretastatin, a vascular‐disrupting agent being studied for treatment of anaplastic thyroid cancer. In 1 patient, an ECG performed per protocol 18 hours after drug initiation showed deep, symmetric T‐wave inversions in limb leads I and aVL and precordial leads V2 through V6. Echocardiography showed mildly reduced overall left ventricular systolic function with akinesis of the entire apex. The patient had mild elevations of troponin I. Coronary angiography revealed no epicardial coronary artery disease. The electrocardiographic and echocardiographic abnormalities resolved after several weeks. The patient remains stable from a cardiovascular standpoint and has not had a recurrence during follow‐up. An electrocardiogram performed per protocol in a second patient showed deep, symmetric T‐wave inversions throughout the precordial leads and a prolonged QT interval. Echocardiography showed mildly reduced left ventricular function with hypokinesis of the apical‐septal wall. Acute coronary syndrome was ruled out, and both the electrocardiographic and echocardiographic changes resolved at follow‐up. Although the patient remained pain‐free without recurrence of anginal symptoms during long‐term follow‐up, the patient developed progressive malignancy and died. Copyright

Umbilical Cord Blood Stem Cells for Myocardial Regeneration and Angiogenesis

Limitations of revascularization for ischemic heart disease include incompleteness of revascularization, even for surgical revascularization, especially for calcified lesions in distal segments of small-caliber vessels. Revascularization has not been shown to regenerate functional, viable myocardium from scarred and infarcted myocardium. Previous alternatives to revascularization such as transmyocardial laser revascularization, gene therapy, and orthotopic heart transplantation also have many disadvantages that limit their use in high-risk patients such as those with recent myocardial infarction and advanced heart failure.

New developments with umbilical cord blood.

In this issue of Cytotherapy, three papers present, between them, the derivation of mesenchymal stromal cells (MSC) and colony-forming unit megakaryocytes (CFU-Meg) from human umbilical cord blood (UCB) cells and their immuno-equivalence to adult bone marrow (BM)-derived MSC. Briefly, Choi et al. [1] describe the derivation of viable MSC from human UCB and use both phenotypic/ enzymatic expression and reverse transcriptase-polymerase chain reaction (RT-PCR) to demonstrate their adipoand osteogenic lineages. They use atelocollagen matrix and type II collagen synthesis to demonstrate the chondrogenic potential of these UCB-derived MSC. In another paper, Shirvaikar et al. [2] describe the generation of CFU-Meg from UCB in the presence of thrombopoietin (TPO) and interleukin-3 (IL-3) and demonstrate synthesis of both matrix metalloproteinase-9 (MMP) and the membrane-type (MT) variety, MT1-MMP. They also demonstrate expression of CXCR4, the unique receptor for the chemokine stromal cell-derived factor-1 (SDF-1), a chemokine important for both progenitor cell homing and up-regulation of MMP-9 and MT1-MMP. Lastly, Ennis et al. [3] explore the immunogenicity of human UCB perivascular cells (HUCPVC) and demonstrate immuno-equivalence to BM-derived MSC using standard lymphoproliferative assays and T-cell CD25 and CD45 cell-surface receptor expression. What is novel about marrow vs. UCB-derived MSC and SDF-1? MSC found in human BM are multipotent progenitors of mesenchymal tissues and have novel regenerative and immune properties [4]. SDF-1 exerts its effect via its unique receptor, CXCR4. SDF-1 is a potent chemoattractant for all cells expressing CXCR4, including T cells and hematopoietic stem cells. Although low levels of CXCR4 expression are found in minor subpopulations of cultured MSC, the majority of marrow and UCBderived MSC lack CXCR4 and, hence, do not migrate toward an SDF-1 gradient. In addition, SDF-1 stimulates pre-B-lymphocyte cell growth, is important in hematopoetic stem cell survival, and increases survival of human CD34 cells [5]. SDF-1 is important in stem cell migration and CXCR4 mediates its effects. SDF-1-induced migration appears to be dependent on CXCR4 expression. SDF-1 activates adhesion molecules on progenitor cells, and monoclonal antibodies (MAb) against SDF-1 inhibit transendothelial migration of hematopoetic progenitor cells [6]. SDF-1 activates CXCR4 CD34 cells and leads to their adhesion and transendothelial migration. In rhabdomyosarcoma cells that are CXCR4 , SDF-1 increases MMP-2 and decreases tissue inhibitors of MMP (TIMP) secretion [7]. Hence, SDF-1 may facilitate, through its actions on CXCR4, stem cell migration to injured tissue and, through its actions on MMP-2 and TIMP, stem cell-mediated repair of injured tissues. Taken together, observations by Shirvaikar et al. on this issue of up-regulation of metalloproteinases by SDF-1 emphasizes the critical role SDF-1 plays in UCB-derived regenerative cellular medicine. We have demonstrated previously that transduction of human MSC with a retroviral vector expressing CXCR4 improved in vitro migration to SDF-1 [8]. However, given safety and ethical concerns over retroviral transduction of human progenitor cells to be administered clinically, identification of a UCB source of progenitor cells with naturally sufficient CXCR4 expression to facilitate SDF-1mediated homing remains an important discovery and has strong potential in cell therapy strategies, both from a safety as well as a feasibility standpoint.