Valérie Planat-Benard

Spontaneous Cardiomyocyte Differentiation From Adipose Tissue Stroma Cells

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. As adipose tissues were recently demonstrated to contain pluripotent stem cells, the emergence of cardiomyocyte phenotype from adipose-derived cells was investigated. We demonstrated that rare beating cells with cardiomyocyte features could be identified after culture of adipose stroma cells without addition of 5-azacytidine. The cardiomyocyte phenotype was first identified by morphological observation, confirmed with expression of specific cardiac markers, immunocytochemistry staining, and ultrastructural analysis, revealing the presence of ventricle- and atrial-like cells. Electrophysiological studies performed on early culture revealed a pacemaker activity of the cells. Finally, functional studies showed that adrenergic agonist stimulated the beating rate whereas cholinergic agonist decreased it. Taken together, this study demonstrated that functional cardiomyocyte-like cells could be directly obtained from adipose tissue. According to the large amount of this tissue in adult mammal, it could represent a useful source of cardiomyocyte progenitors.

Transplantation of adipose derived stromal cells is associated with functional improvement in a rat model of chronic myocardial infarction

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.

Adipose-derived stromal cells: Their identity and uses in clinical trials, an update

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 phaseu2005Iu2005and 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.

Phase I trial: the use of autologous cultured adipose-derived stroma/stem cells to treat patients with non-revascularizable critical limb ischemia.

BACKGROUND AIMSnNon-revascularizable critical limb ischemia (CLI) is the most severe stage of peripheral arterial disease, with no therapeutic option. Extensive preclinical studies have demonstrated that adipose-derived stroma cell (ASC) transplantation strongly improves revascularization and tissue perfusion in ischemic limbs. This study, named ACellDREAM, is the first phase I trial to evaluate the feasibility and safety of intramuscular injections of autologous ASC in non-revascularizable CLI patients.nnnMETHODSnSeven patients were consecutively enrolled, on the basis of the following criteria: (i) lower-limb rest pain or ulcer; (ii) ankle systolic oxygen pressurexa0<50 or 70xa0mm Hg for non-diabetic and diabetic patients, respectively, or first-toe systolic oxygen pressurexa0<30xa0mm Hg or 50xa0mm Hg for non-diabetic and diabetic patients, respectively; (iii) not suitable for revascularization. ASCs from abdominal fat were grown for 2 weeks and were then characterized.nnnRESULTSnMore than 200 million cells were obtained, with almost total homogeneity and no karyotype abnormality. The expressions of stemness markers Oct4 and Nanog were very low, whereas expression of telomerase was undetectable in human ASCs compared with human embryonic stem cells. ASCs (10(8)) were then intramuscularly injected into the ischemic leg of patients, with no complication, as judged by an independent committee. Trans-cutaneous oxygen pressure tended to increase in most patients. Ulcer evolution and wound healing showed improvement.nnnCONCLUSIONSnThese 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.

Adipose-derived cardiomyogenic cells: in vitro expansion and functional improvement in a mouse model of myocardial infarction

AIMSnCells derived from the stroma vascular fraction (SVF) of mouse adipose tissue can spontaneously give rise to rare, functional, cardiac-like cells in vitro. This study aimed to improve the production of adipose-derived cardiomyogenic cells (AD-CMG), to characterize them and to assess their cardiac fate and functional outcomes after their administration in a mouse model of acute myocardial infarction.nnnMETHODS AND RESULTSnThe culture process optimized to improve in vitro cardiac specification consisted of a primary culture of murine SVF cells in semi-solid methylcellulose medium, a selection of AD-CMG cell clusters, and a secondary culture and expansion in BHK21 medium. AD-CMG cells were CD29(+), CD31(-), CD34(-), CD44(+), CD45(-), CD81(+), CD90(-), CD117(-), and Flk-1(-) and expressed several cardiac contractile proteins. After 1, 2, and 4 weeks of their injection in mice having acute myocardial infarction, a strong presence of green fluorescent protein-positive cells was identified by immunohistochemistry as well as quantitative polymerase chain reaction. Echocardiography showed a significant reduction of remodelling and stability of left ventricle ejection fraction in the AD-CMG cell-treated group vs. controls. Vascular density analysis revealed that AD-CMG administration was also associated with stimulation of angiogenesis in peri-infarct areas.nnnCONCLUSIONnCardiomyogenic 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.

Epicardial adipose stem cell sheets results in greater post-infarction survival than intramyocardial injections

AIMSnIntramyocardial injections of cells can damage tissue and enhance dissociation-induced cell death. We assessed whether epicardial delivery of cell sheets could overcome these issues in a rat model of chronic myocardial infarction.nnnMETHODS AND RESULTSnEighty-two rats that had undergone coronary ligation and simultaneous harvest of fat tissue to yield the adipose-derived stromal cell (ADSC) fraction were randomized 1 month after infarction to receive injections of either control medium (n= 24) or 10 × 10(6) autologous ADSC (n= 37) or the epicardial deposit, onto the infarcted area, of a trilayered ADSC sheet (10 × 10(6), n= 21) prepared by culturing cells on temperature-sensitive dishes. Some treated rats received green fluorescent protein labelled ADSC. Survival, function, and cell engraftment were blindly assessed after 2 months. Prior to implantation, cell sheets and suspended cells were assessed for the expression of extracellular matrix constituents and molecules involved in angiogenesis and cardiac remodelling. The survival rate of rats receiving the cell sheets was significantly higher than after cell injections (73 vs. 41%, P = 0.01). This correlated with the absence of left ventricular (LV) remodelling in the cell sheet group, as end-diastolic volume only increased by 2.8% compared with baseline [95% confidence interval (CI): -18.7%; +30.0%, P = 0.81] vs. increases of 25.9% (-0.4%; +59.2%, P = 0.05) and 51.2% (+18.6%; +92.8, P = 0.001) in the cell and medium injection groups, respectively. Sheets also resulted in a greater cell engraftment possibly related to the greater expression of extracellular matrix constituents.nnnCONCLUSIONnThe 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.

Preconditioning by Mitochondrial Reactive Oxygen Species Improves the Proangiogenic Potential of Adipose-Derived Cells-Based Therapy

Objective—Transplantation of adipose-derived stroma cells (ADSCs) stimulates neovascularization after experimental ischemic injury. ADSC proangiogenic potential is likely mediated by their ability to differentiate into endothelial cells and produce a wide array of angiogenic and antiapoptotic factors. Mitochondrial reactive oxygen species (ROS) have been shown to control ADSC differentiation. We therefore hypothesized that mitochondrial ROS production may change the ADSC proangiogenic properties. Methods and Results—The use of pharmacological strategies (mitochondrial inhibitors, antimycin, and rotenone, with or without antioxidants) allowed us to specifically and precisely modulate mitochondrial ROS generation in ADSCs. We showed that transient stimulation of mitochondrial ROS generation in ADSCs before their injection in ischemic hindlimb strongly improved revascularization and the number of ADSC-derived CD31-positive cells in ischemic area. Mitochondrial ROS generation increased the secretion of the proangiogenic and antiapoptotic factors, VEGF and HGF, but did not affect ADSC ability to differentiate into endothelial cells, in vitro. Moreover, mitochondrial ROS-induced ADSC preconditioning greatly protect ADSCs against oxidative stress–induced cell death. Conclusion—Our study demonstrates that in vitro preconditioning by moderate mitochondrial ROS generation strongly increases in vivo ADSC proangiogenic properties and emphasizes the crucial role of mitochondrial ROS in ADSC fate.

Human bone marrow adipocytes support complete myeloid and lymphoid differentiation from human CD34+ cells

In humans, the role of bone marrow (BM) adipocytes in supporting haematopoiesis has been questioned. A co‐culture system of CD34+ cells seeded onto either BM undifferentiated mesenchymal stem cells or differentiated adipocytes showed that BM adipocytes did not support the maintenance of immature progenitors but enabled their complete differentiation along the myeloid and lymphoid pathways. These properties appear to be opposite to those of osteoblasts, although both cell types share a common mesenchymal progenitor. These results suggest that stromal cells play a variety of roles in the haematopoietic microenvironment, which could be significant in situations such as osteoporosis or ageing.

Human adipose derived stroma/stem cells grow in serum-free medium as floating spheres.

With the goal of obtaining clinically safe human adipose-derived stroma/stem cells (ASC) and eliminating the use of serum, we have developed a new culture system that allows the expansion of ASC as spheres in a defined medium. These spheres can be passaged several times. They are not only aggregated cells but rather originate from single cells as clonal spheres can be obtained after seeding at very low density and reform clonal spheres after dissociation. These spheres can also revert to monolayer growth when plated in medium containing human plasma and even generate fibroblast-like colonies (CFU-f). Under several differentiation-specific media, spheres-derived ASC maintain their capacity to differentiate into osteoblasts, endothelial cells and adipocytes. These results indicate that human ASC can be maintained in a serum-free 3D culture system, which is of great interest for the expansion in bioreactors of autologous ASC and their use in clinical trials.

Concise Review: Mesenchymal Stromal Cells Used for Periodontal Regeneration: A Systematic Review

Periodontitis is a chronic infectious disease of the soft and hard tissues supporting the teeth. Recent advances in regenerative medicine and stem cell biology have paved the way for periodontal tissue engineering. Mesenchymal stromal cells (MSCs) delivered in situ to periodontal defects may exert their effects at multiple levels, including neovascularization, immunomodulation, and tissue regeneration. This systematic review had two goals: (a) to objectively quantify key elements for efficacy and safety of MSCs used for periodontal regeneration and (b) to identify patterns in the existing literature to explain differences between studies and suggest recommendations for future research. This systematic review provided good evidence of the capacity of MSCs to regenerate periodontal tissues in animals; however, experimentally generated defects used in animal studies do not sufficiently mimic the pathophysiology of periodontitis in humans. Moreover, the safety of such interventions in humans still needs to be studied. There were marked differences between experimental and control groups that may be influenced by characteristics that are crucial to address before translation to human clinical trials. We suggest that the appropriate combination of cell source, carrier type, and biomolecules, as well as the inclusion of critical path issues for a given clinical case, should be further explored and refined before transitioning to clinical trials. Future studies should investigate periodontal regenerative procedures in animal models, including rodents, in which the defects generated are designed to more accurately reflect the inflammatory status of the host and the shift in their pathogenic microflora.