Tengiz Tkebuchava

Clonally expanded novel multipotent stem cells from human bone marrow regenerate myocardium after myocardial infarction

We have identified a subpopulation of stem cells within adult human BM, isolated at the single-cell level, that self-renew without loss of multipotency for more than 140 population doublings and exhibit the capacity for differentiation into cells of all 3 germ layers. Based on surface marker expression, these clonally expanded human BM-derived multipotent stem cells (hBMSCs) do not appear to belong to any previously described BM-derived stem cell population. Intramyocardial transplantation of hBMSCs after myocardial infarction resulted in robust engraftment of transplanted cells, which exhibited colocalization with markers of cardiomyocyte (CMC), EC, and smooth muscle cell (SMC) identity, consistent with differentiation of hBMSCs into multiple lineages in vivo. Furthermore, upregulation of paracrine factors including angiogenic cytokines and antiapoptotic factors, and proliferation of host ECs and CMCs, were observed in the hBMSC-transplanted hearts. Coculture of hBMSCs with CMCs, ECs, or SMCs revealed that phenotypic changes of hBMSCs result from both differentiation and fusion. Collectively, the favorable effect of hBMSC transplantation after myocardial infarction appears to be due to augmentation of proliferation and preservation of host myocardial tissues as well as differentiation of hBMSCs for tissue regeneration and repair. To our knowledge, this is the first demonstration that a specific population of multipotent human BM-derived stem cells can induce both therapeutic neovascularization and endogenous and exogenous cardiomyogenesis.

Unexpected Severe Calcification After Transplantation of Bone Marrow Cells in Acute Myocardial Infarction

Background— There has been a rapid increase in the number of clinical trials using unselected bone marrow (BM) cells or the mononuclear fraction of BM cells for treating ischemic heart diseases. Thus far, no significant deleterious effects or complications have been reported in any studies using BM-derived cells for treatment of various cardiac diseases. Methods and Results— Seven-week-old female Fisher-344 rats underwent surgery to induce acute myocardial infarction and were randomized into 3 groups of 16 rats, each receiving intramyocardial injection of either 7×105 DiI-labeled total BM cells (TBMCs), the same number of DiI-labeled, clonally expanded BM multipotent stem cells, or the same volume of phosphate-buffered saline in the peri-infarct area. Echocardiography 2 weeks after cell transplantation indicated intramyocardial calcification in 4 of 14 surviving rats (28.5%) in the TBMC group. Histological examination with hematoxylin and eosin staining and von Kossa staining confirmed the presence of extensive intramyocardial calcification. Alkaline phosphatase staining revealed strong positivity surrounding the calcified area suggestive of ongoing osteogenic activity. Fluorescent microscopic examination revealed that acellular calcific areas were surrounded by DiI-labeled TBMCs, suggesting the direct involvement of transplanted TBMCs in myocardial calcification. In contrast, in hearts receiving equal volumes of saline or BM multipotent stem cells delivered in the same manner, there was no evidence of calcification. Conclusions— These results demonstrate that direct transplantation of unselected BM cells into the acutely infarcted myocardium may induce significant intramyocardial calcification.

Sonic hedgehog myocardial gene therapy: tissue repair through transient reconstitution of embryonic signaling

Sonic hedgehog (Shh) is a crucial regulator of organ development during embryogenesis. We investigated whether intramyocardial gene transfer of naked DNA encoding human Shh (phShh) could promote a favorable effect on recovery from acute and chronic myocardial ischemia in adult animals, not only by promoting neovascularization, but by broader effects, consistent with the role of this morphogen in embryogenesis. After Shh gene transfer, the hedgehog pathway was upregulated in mammalian fibroblasts and cardiomyocytes. This resulted in preservation of left ventricular function in both acute and chronic myocardial ischemia by enhanced neovascularization, and reduced fibrosis and cardiac apoptosis. Shh gene transfer also enhanced the contribution of bone marrow–derived endothelial progenitor cells to myocardial neovascularization. These data suggest that Shh gene therapy may have considerable therapeutic potential in individuals with acute and chronic myocardial ischemia by triggering expression of multiple trophic factors and engendering tissue repair in the adult heart.

VEGF-C gene therapy augments postnatal lymphangiogenesis and ameliorates secondary lymphedema

Although lymphedema is a common clinical condition, treatment for this disabling condition remains limited and largely ineffective. Recently, it has been reported that overexpression of VEGF-C correlates with increased lymphatic vessel growth (lymphangiogenesis). However, the effect of VEGF-C-induced lymphangiogenesis on lymphedema has yet to be demonstrated. Here we investigated the impact of local transfer of naked plasmid DNA encoding human VEGF-C (phVEGF-C) on two animal models of lymphedema: one in the rabbit ear and the other in the mouse tail. In a rabbit model, following local phVEGF-C gene transfer, VEGFR-3 expression was significantly increased. This gene transfer led to a decrease in thickness and volume of lymphedema, improvement of lymphatic function demonstrated by serial lymphoscintigraphy, and finally, attenuation of the fibrofatty changes of the skin, the final consequences of lymphedema. The favorable effect of phVEGF-C on lymphedema was reconfirmed in a mouse tail model. Immunohistochemical analysis using lymphatic-specific markers: VEGFR-3, lymphatic endothelial hyaluronan receptor-1, together with the proliferation marker Ki-67 Ab revealed that phVEGF-C transfection potently induced new lymphatic vessel growth. This study, we believe for the first time, documents that gene transfer of phVEGF-C resolves lymphedema through direct augmentation of lymphangiogenesis. This novel therapeutic strategy may merit clinical investigation in patients with lymphedema.

Catheter-based myocardial gene transfer utilizing nonfluoroscopic electromechanical left ventricular mapping.

OBJECTIVES This study investigated the feasibility and safety of percutaneous, catheter-based myocardial gene transfer. BACKGROUND Direct myocardial gene transfer has, to date, required direct injection via an open thoracotomy. METHODS Electroanatomical mapping was performed to establish the site of left ventricular (LV) gene transfer. A steerable, deformable 7F catheter with a 27G needle, which can be advanced 3 to 5 mm beyond its distal tip, was then directed to previously acquired map sites, the needle was advanced, and injections were made into the LV myocardium. RESULTS In two pigs in which methylene blue dye was injected, discretely stained LV sites were observed at necropsy in each pig, corresponding to the injection sites indicated prospectively by the endocardial map. In six pigs in which the injection catheter was used to deliver plasmid using cytomegalovirus promoter/enhancer, encoding nuclear-specific LacZ gene (pCMV-nlsLacZ) (50 microg/ml) to a single LV myocardial region, peak beta-galactosidase activity after five days (relative light units [RLU], mean 135,333+/-28,239, range = 31,508 to 192,748) was documented in the target area of myocardial injection in each pig. Percutaneous gene transfer of pCMV-nlsLacZ (50 microg/ml) was also performed in two pigs with an ameroid constrictor applied to the left circumflex coronary artery, in each pig, peak beta-galactosidase activity after five days (214,851 and 23,140 RLU) was documented at the injection site. All pigs survived until sacrifice, and no complications were observed with either the mapping or the injection procedures. CONCLUSIONS Percutaneous myocardial gene transfer can be successfully achieved in normal and ischemic myocardium without significant morbidity or mortality. These findings establish the potential for minimally invasive cardiovascular gene transfer.

Synergistic effect of bone marrow mobilization and vascular endothelial growth factor-2 gene therapy in myocardial ischemia.

Background—We performed a series of investigations to test the hypothesis that combining angiogenic gene therapy and cytokine (CK)-induced endothelial progenitor cell mobilization would be superior to either strategy alone for treatment of chronic myocardial ischemia. Methods and Results—A swine model of chronic myocardial ischemia and a murine model of acute myocardial infarction were used in this study. In both models, animals were randomly assigned to 1 of 4 treatment groups: Combo group, intramyocardial vascular endothelial growth factor (VEGF)-2 gene transfer plus subcutaneous injection of CKs; VEGF-2, VEGF-2 gene transfer plus saline subcutaneously injected; CK, empty vector transfer plus CKs; and control, empty vector plus subcutaneous saline. Acute myocardial infarction was also induced in wild-type mice 4 weeks after bone marrow transplantation from enhanced green fluorescent protein transgenic mice to permit observation of bone marrow–derived cells in the myocardium after acute myocardial infarction. In chronic myocardial ischemia, combination therapy resulted in superior improvement in all indexes of perfusion and function compared with all other treatment groups. In the bone marrow transplant mice, double immunofluorescent staining revealed that the combination of CK-induced mobilization and local VEGF-2 gene transfer resulted in a significant increase in the number of bone marrow–derived cells incorporating into the neovasculature, indicating that recruitment and/or retention of bone marrow–derived progenitors was enhanced by mobilization and that local VEGF-2 gene transfer can provide signals for recruitment or incorporation of circulating progenitor cells. Conclusions—Mobilization of endothelial progenitor cells with cytokines potentiates VEGF-2 gene therapy for myocardial ischemia and enhances bone marrow cell incorporation into ischemic myocardium.

Autologous transplantation of endothelial progenitor cells genetically modified by adeno-associated viral vector delivering insulin-like growth factor-1 gene after myocardial infarction.

The regenerative potential of bone marrow-derived endothelial progenitor cells (EPCs) has been adapted for the treatment of myocardial and limb ischemia via ex vivo expansion. We sought to enhance EPC function by the efficient genetic modification of EPCs in a rat model of myocardial infarction. Peripheral blood EPCs were expanded and transduced, using adeno-associated virus (AAV). AAV-mediated EPC transduction efficacy was 23 ± 1.2%, which was improved by 4.0- to 7.2-fold after pretreatment with the tyrosine kinase inhibitor genistein. Adult rats (n = 7 in each group) underwent myocardial infarction by left anterior descending coronary artery occlusion, and received autologous EPCs transduced by AAV-IGF-1 or AAV-lacZ into the periinfarct area. Echocardiography demonstrated that cardiac function in the IGF-1-EPC group was significantly improved compared with the lacZ-EPC control group 12 weeks after myocardial infarction. In addition, IGF-1-expressing EPCs led to reduced cardiac apoptosis, increased cardiomyocyte proliferation, and increased numbers of capillaries in the periinfarct area. AAV expression was limited to the targeted heart region only. Pretreatment with genistein markedly improved AAV transduction of EPCs. IGF-1-expressing EPCs exhibit favorable cell-protective effects with tissue-limited expression in rat heart postinfarction.

229. Use of rAAV Transduced Endothelial Progenitor Cells for the Treatment of Myocardial Infarction in Rat Model

|[bull]| Background- The regenerative potential of bone marrow-derived endothelial progenitor cells (EPCs) has been adapted for the treatment of myocardial and limb ischemia via ex vivo expansion. Biotechnologically, it is plausible to constitute a potential means of addressing enhancement of EPC functions by efficient genetic modification of EPCs. Recombinant adeno-associated virus (rAAV) is currently being recognized as a gene delivery tool, and we recently demonstrated that rAAV vectors are capable of transducing bone marrow cells. Insulin-like growth factor-1 (IGF-1), which belongs to the insulin family of peptides and acts on a variety of functions such as anti-apoptosis, angiogenesis and proliferation of cells.