Background— Adipose tissue development and remodeling are closely associated with the growth of vascular network. We hypothesized that adipose tissue may contain progenitor cells with angiogenic potential and that therapy based on adipose tissue-derived progenitor cells administration may constitute a promising cell therapy in patients with ischemic disease. Methods and Results— In mice, cultured stromal-vascular fraction (SVF) cells from adipose tissue have a great proangiogenic potential, comparable to that of bone marrow mononuclear cells in the mouse ischemic hindlimb model. Similarly, cultured human SVF cells differentiate into endothelial cells, incorporate into vessels, and promote both postischemic neovascularization in nude mice and vessel-like structure formation in Matrigel plug. In vitro, these cells represent a homogeneous population of CD34- and CD13-positive cells, which can spontaneously express the endothelial cell markers CD31 and von Willebrand factor when cultured in semisolid medium. Interestingly, dedifferentiated mature human adipocytes have the potential to rapidly acquire the endothelial phenotype in vitro and to promote neovascularization in ischemic tissue and vessel-like structure formation in Matrigel plug, suggesting that cells of endothelial and adipocyte phenotypes may have a common precursor. Conclusions— This study demonstrates, for the first time, that adipocytes and endothelial cells have a common progenitor. Such adipose lineage cells participate in vascular-like structure formation in Matrigel plug and enhance the neovascularization reaction in ischemic tissue. These results also highlight the concept that adipose lineage cells represent a suitable new cell source for therapeutic angiogenesis in ischemic disease.

Abstract-Cardiomyocyte regeneration is limited in adult life. Thus, the identification of a putative source of cardiomyocyte progenitors is of great interest to provide a usable model in vitro and new perspective in regenerative therapy. Key Words: cardiomyocytes Ⅲ adipose tissue Ⅲ differentiation Ⅲ stem cells Ⅲ cell therapy C ardiomyocyte differentiation mainly takes place during neonatal and perinatal life. In adult life, the regenerative potential of cardiac tissue is limited and is not sufficient to prevent from the degeneration occurring in pathological conditions such as myocardial infarction. 1 Cell transplantation seems to be an alternative to overcome this problem. 2 This led to numerous investigations to identify a putative source of transplanted cells and to better understand cardiomyocyte proliferation and differentiation in order to drive the fate of stem cells toward this process. Different sources, ie, embryonic, fetal, and adult cells have been investigated and tested. 3-8 Among them, mesenchymal stem cells (MSCs) isolated from bone marrow are accepted to give rise to connective tissue cell types. Their differentiation toward cardiomyocyte was obtained in vitro and in vivo. However, immortalized MSCs and treatment with the DNA demethylation agent 5-azacytidine was necessary to reveal their cardiogenic potential in vitro. 6 Adipose tissues are mesodermic tissues, which develop during perinatal and postnatal life. 9 They are strongly involved in various metabolic disorders such as obesity. Tremendous changes in adipose mass are achieved through highly controlled processes such as angiogenesis, precursor recruitment, proliferation, differentiation, dedifferentiation, and apoptosis as well. More recently, differentiation of cells derived or purified from adipose tissue toward phenotypes different from adipocyte was described. 10 -13 However, the characterization of cells with such potential remains to be done. The present statement is that adipose tissue consists of mature adipocytes and the stroma vascular fraction (SVF). SVF is a heterogeneous cell population. Among them the identified ones are vascular cells (endothelial, smooth muscle cell, circulating blood cells) and an undefined fibroblast-like cell population recently described as a multipotential stem cell population for various mesodermic lineage. 10 -13 This led us to test the in vitro cardiomyogenic potential of cells purified from adipose tissue. In the results reported in this study, adipose-derived cells (SVF cells) from primary culture spontaneously differentiate into cells with morphological, molecular, and functional properties of cardiomyocytes. Materials and Methods AnimalsSix-week-old adult male C57Bl/6N mice (Harlan, France) were housed in conventional animal quarters (SPS barrier facility). Mice were killed by cervical dislocation under CO 2 anesthesia. All procedures were performed according to SELASA norms.

These data demonstrate the feasibility and safety of autologous ASC transplantation in patients with objectively proven CLI not suitable for revascularization. The improved wound healing also supports a putative functional efficiency.

In adults, adipose tissue is abundant and can be easily sampled using liposuction. Largely involved in obesity and associated metabolic disorders, it is now described as a reservoir of immature stromal cells. These cells, called adipose-derived stromal cells (ADSCs) must be distinguished from the crude stromal vascular fraction (SVF) obtained after digestion of adipose tissue. ADSCs share many features with mesenchymal stem cells derived from bone marrow, including paracrine activity, but they also display some specific features, including a greater angiogenic potential. Their angiogenic properties as well as their paracrine activity suggest a putative tumor-promoting role for ADSCs although contradictory data have been published on this issue. Both SVF cells and ADSCs are currently being investigated in clinical trials in several fields (chronic inflammation, ischemic diseases, etc.). Apart from a phase III trial on the treatment of fistula, most of these are in phase I and use autologous cells. In the near future, the end results of these trials should provide a great deal of data on the safety of ADSC use.

Aims: To determine the effect of transplantation of undifferentiated and cardiac pre-differentiated adipose stem cells compared with bone marrow mononuclear cells (BM-MNC) in a chronic model of myocardial infarction. Methods: Ninety-five Sprague-Dawley rats underwent left coronary artery ligation and after 1 month received by direct intramyocardial injection either adipose derived stem cells (ADSC), cardiomyogenic cells (AD-CMG) or BM-MNC from enhanced-Green Fluorescent Protein (eGFP) mice. The control group was treated with culture medium. Heart function was assessed by echocardiography and 18 F-FDG microPET. Cell engraftment, differentiation, angiogenesis and fibrosis in the scar tissue were also evaluated by (immuno)histochemistry and immunofluorescence. Results: One month after cell transplantation, ADSC induced a significant improvement in heart function (LVEF 46.3 ± 9.6% versus 27.7 ± 8% pre-transplant) and tissue viability (64.78 ± 7.2% versus 55.89 ± 6.3% pre-transplant). An increase in the degree of angiogenesis and a decrease in fibrosis were also detected. Although transplantation of AD-CMG or BM-MNC also had a positive, albeit smaller, effect on angiogenesis and fibrosis in the infarcted hearts, this benefit did not translate into a significant improvement in heart function or tissue viability. Conclusion: These results indicate that transplantation of adipose derived cells in chronic infarct provides a superior benefit to cardiac predifferentiated ADSC and BM-MNC.

The better preservation of LV geometry afforded by ADSC sheets is associated with increased survival and engraftment, which supports the concept of an epicardial delivery of cell-seeded biomaterials.

Cardiomyogenic cells can be selected and expanded in large amounts from mouse adipose tissue. They can survive and differentiate in an acute myocardial infarction model, avoiding remodelling and impairment of cardiac function, and can promote neo-vascularization in the ischaemic heart.

Adipose stroma/stem cells (ASC) represent an ideal source of autologous cells for cell-based therapy. Their transplantation enhances neovascularization after experimental ischemic injury. Aging is associated with a progressive decrease in the regenerative potential of mesenchymal stem cells (MSCs) from bone marrow. This work aims to determine the aging effect on human ASC capacities. First, we show that aging impairs angiogenic capacities of human ASC (hASC) in a mouse ischemic hindlimb model. Although no change in hASC number, phenotype, and proliferation was observed with aging, several mechanisms involved in the adverse effects of aging have been identified in vitro combining a concomitant decrease in (i) ASC ability to differentiate towards endothelial cells, (ii) secretion of proangiogenic and pro-survival factors, and (iii) oxidative stress. These effects were counteracted by a hypoxic preconditioning that improved in vivo angiogenic capacities of hASC from older donors, while hASC from young donors that have a strong ability to manage hypoxic stress were not. Finally, we identified reactive oxygen species (ROS) generation as a key signal of hypoxia on hASC angiogenic capacities. This study demonstrates for the first time that age of donor impaired angiogenic capacities of hASC in ischemic muscle and change in ROS generation by hypoxic preconditioning reverse the adverse effect of aging.