Despite significant advances in medical and device therapy over the past decades, chronic heart failure (HF) represents an increasingly common and debilitating disorder worldwide. Even in 21st century HF carries a dismal prognosis and is related to unacceptably high mortality rates . Although current HF treatment options have been shown to improve HF symptoms and signs, to reduce heart failure-related hospital admissions and above all to improve patients‘ survival , no therapeutic modality to date has addressed the repair of damaged/lost myocardial tissue. The latter represents the central common underlying pathophysiologic mechanisms of heart failure development and progression regardless of the initial trigger of myocardial damage. Ever since the first successful use of bone marrow stem cells in experimental model of acute myocardial infarction was published  there has been a growing interest in the HF community to apply stem cell therapy for the treatment of chronic ischemic HF. Although especially in the younger (< 70 years) population of heart failure patients chronic non-ischemic heart failure (DCMP) has become the most prevalent form of the disease leading to heart transplantation  it has gained surprisingly little attention in the field of stem cell therapy with only a handful of studies addressing this steadily increasing pool of patients (Table 1).
Thus, the aim of this review is to discus current status and recent advances of stem cell therapy in the treatment od DCMP, with emphasis on patient selection, stem cell types and clinical efficacy of this treatment modality.
|Study name||Study design||Study phase||Pre-specified endpoint||Method of LVEF evaluation||Number of patients||Follow-up (mths)||Cell type||Number of transplanted cells (million)||Cell delivery method|
|TOPCARE-DCM12 (NCT00284713)||prospective, open-label||II||• absolute change in regional LV wall motion of the target area||LV angiography||33||12||BMMC||259 ± 135||IC|
|ABCD13 (NCT unavailable)||prospective, randomized, open-label||II||• change in NYHA functional class, • change in LVEF, • mortality, • histopathologic evaluation||Echo||44 (24 treated/20 controls)||6||BMMC||28 ± 16||IC|
|Bocchi et al.14 (NCT unavailable)||prospective, randomized, open-label||II||• improvement in LVEF • exercise capacity • QoL||Echo||40 (23 treated/17 controls)||1||BMMC||Not available||IC|
|REGENERATE-DCM15 (NCT01302171)||prospective, randomized, placebo-controlled, double-blind||II||• change in global LVEF at 3 months • change in global LVEF at 12 months • exercise capacity • QoL • change in NT-proBNP||CMR/cCT||60 (15 peripheral G-CSF, 15 peripheral placebo, 15 IC stem cells, 15 IC serum)||12||BMMC||216 ± 221||IC|
|Vrtovec et al17 (NCT00629018)||prospective, randomised, open-label||II||• change in global LVEF at 12 months • exercise capacity • change in NT-proBNP||Echo||55 (28 treated/27 controls)||12||HSC (CD34+)||123 ± 23||IC|
|Vrtovec et al18 (NCT01350310)||prospective, randomised, open-label||II||• change in global LVEF at 12 months • exercise capacity • change in NT-proBNP||Echo||110 (55 treated/ 55 controls)||60||HSC (CD34+)||113 ± 26||IC|
|Vrtovec et al19 (no NCT number)||prospective, randomised, open-label||II||change in global LVEF at 12 months • exercise capacity • change in NT-proBNP||Echo||40 (20 IC injections /20 TE injections)||6||HSC (CD34+)||IC: 103 ± 27 TE: 105 ± 31||IC/TE|
|Butler et al.22 (NCT02467387)||prospective, randomized, single-blind, placebo-controlled||II||• all-cause mortality • all-cause hospitalizations • adverse events • LVEF • exercise capacity • QoL • change in NT-proBNP||CMR||22 (10 treated/12 placebo)||6||alloMSC||1.5 million cells/kg||IV|
|POSEIDON-DCM23 (NCT01392625)||Prospective, randomised, open-label||I/II||• adverse events • LVEF • exercise capacity • QoL||CMR/cCT/ Echo||37 (19 alloMSC/ 18 autoMSC)||12||Allo vs. autoMSC||100||TE|
PATHOPHYSIOLOGIC BASIS OF NON-ISCHEMIC HEART FAILURE AND THE SIGNIFICANCE OF MICROVASCULAR ISCHEMIA
DCMP is characterized by left- or biventricular dilation with concomitant systolic dysfunction in the absence of extrinsic factors that may cause similar phenotype such as coronary artery disease, arterial hypertension, valvular heart disease or congenital heart disease. This disorder can develop at any age and regardless of gender or race . The etiology of DCMP is multifactorial and currently it is believed that it occurs due to the interplay between genetic factors, infectious (mainly viral) causes, mechanical stress, and toxicity-related causes . Macroscopically, enlargment of all four chambers with relatively more pronounced dilation of the ventricles than the atria is seen. Histological examination of the ventricular myocardium occasionally shows areas of cardiomyocite necrosis/apoptosis with inflammatory cell infiltration and typically areas of perivascular and interstitial replacement fibrosis are seen. Electrophysiological data further suggest that myocardial scar burden and distribution pattern differ significantly between ischemic and non-ischemic chronic heart failure patients being significantly less in quantity and more diffuse in distribution in the latter group . On subcellular level abnormal shapes, sizes and numbers of mitochondira have been reported in DCMP. The exact pathophysiological mechanisms that underly these changes still remain poorly understood and it is currently believed that the interplay between altered sarcomeric and cytoskeletal proteins, direct pathogen damage, post-infection immune and autoimmune mechanisms and free oxygen radical species may represent the foundation of the development and progression of DCMP .
Additionally, defective vascularization with impaired vasculogenesis and angiogenesis have also been documented in patients with DCMP  suggesting that, in addition to myocardial inflammation, microvascular ischemia may represent one of the key mechanisms involved in the developement of DCMP and its progression to end-stage heart failure. Currently the mechanisms that lead to altered vasculogenesis and angiogenesis in DCMP remain largely unexplained. They appear to be related to impaired myocardial homing, mediated mainly through SDF-1/CXCR4 axis, and survival of circulating CD34+ cells and endothelial progenitor cells (EPC) in the earlier phases (NYHA I and II) of disease and to the exhaustion of the pools of these progenitors in the later phases (NYHA III and IV) of the disease [8, 9, 10].
STEM CELL TYPES
Generally, stem cells are defined as a population of self-renewing cells with the potential to generate daughter cells with the capability to differentiate along specific cell lineages . In the last decade several stem cell types have been studied for the treatment od HF, alone or in combination, and for the most part the studies have focused on ischemic HF. Only a handful of clinical trials specifically addressed the stem cell therapy in the setting of DCMP (Table 1).
Bone Marrow-Derived Stem Cells (BMMC)
Bone marrow is the source of mixed population of hematopoetic and nonhematopoetic stem cells. Both have been shown to possess the ability for transdifferentiation into different cell lineages if tranferred to a tissue-specific cytokine mileu. Due to the easy access and straightforward procurement, this stem cell type has understandably gained the widest attention in preclinical and early clinical trials. Mostly, BMMC were studied in the setting of ischemic HF. However, several studies did analyse safety and efficiency of this stem cell population also in patients with DCMP.
In TOPCARE-DCM study (A pilot trial to assess potential effects of selective intracoronary bone marrow-derived progenitor cell infusion in patients with nonischemic dilated cardiomyopathy; NCT00284713) intracoronary infusion of BMMC into the left anterior descending coronary artery was performed in 33 patients by an over-the-wire baloon catheter. This resulted in improved regional wall motion of the injected area and global left ventricular myocardial performance with an average increase of left ventricular ejection fraction (LVEF) by 3 %. Furthermore at 12 months follow-up, NT-proBNP serum levels were persistetnly decreased suggesting a potential beneficial effect of BMMC infusion on LV remodeling process . In ABCD trial (Percutaneous intracoronary cellular cardiomyoplasty for nonischemic cardiomyopathy; NCT unavailable), 44 patients with non-ischemic HF received either intracoronary injection of BMMC (24 patients) or sham infusion without stem cells (20 patients). In the treatment arm 2/3 of the cell suspension was infused in the left coronary system and 1/3 in the right coronary system . During the 3-month follow-up LVEF improved in the treatment arm by 5.4 % but remained largely unchanged in the control arm and similarly improvement in NYHA functional class was observed in treatment arm but not in controls . Similarly, in a study of patients with refractory non-ischemic HF, infusion of BMMC into the left main coronary artery was associated with improved myocardial performance, maximal oxygen consumption, and quality of life . Recently REGENERATE-DCM (Randomized trial of combination cytokine and adult autologous bone marrow progenitor cell administration in patients with non-ischaemic dilated cardiomyopathy; NCT 01302171) corroborated these encouraging early results by showing a 5,4 % increase in LVEF in 15 DCMP patients who received intracoronary infusion of BMMC suspension. This improvement in left ventricular function was additionally associated with a decrease in NYHA functional class, reduction of NT-proBNP serum levels and increased patient exercise capacity, all of which persisted over the 1 year follow-up period. Of note, this trial also explored possible effects of peripheral G-CSF stimulation on LVEF and found no correlation, discarding the argument that peripheral G-CSF stimulation itself is sufficient to promote homing and engraftment of circulating stem cells to the diseased myocardium .
Taken together these data suggest that BMMC therapy may be of potential clinical benefit in patients with DCMP. However, the variations in BMMC populations, patient selection criteria and delivery methods used in these studies make direct comparisons between them challenging and any extrapolation to a wider clinical utility very difficult.
Hematopoietic Stem Cells (HSC)
HSC represent a part of hematopoetic cell compartment of the bone marrow that differentiate along lymphoid and myeloid lineages to form mature white blood cells. HSC are positive for CD34+ surface marker and have been shown to have a potential to differentiate into endothelial cells and thus promote target tissue neovascularization  directly addressing one of the main pathophysiologic mechanisms involved in DCMP. Since in comparisson to BMMC their procurement is more cumbersome and associated with more complex logistics and higher cost it is not surprising that this stem cell population has not been extensively studied.
In the first clinical trial to assess the effects of stem cell therapy in DCMP 28 patients received intracoronary application of CD34+ stem cells obtained through G-CSF stimulation followed by periheral blood apheresis and immunomagnetic selection. In comparisson to control group 5 % increase in LVEF was observed in stem cell group at 1 year follow-up. Additionally, improved patients‘ functional capacity and reduced neurohumoral activation were observed . Importantly, these positive effects persisted through the 5-year follow-up period and translated in improved survival of patients receiving CD34+ cell therapy . Recently published data further suggest that transendocardial stem cell injecions may be preferred to intracoronary stem cell infusion in this patient population. It was shown that transendocardial stem cell injections yielded 5-times higher retention rates (around 18 %) than intracoronary stem cell infusion (around 4 %) which in turn translated into better functional recovery of the left ventricle (LVEF improved by 8 % in transendocardial group vs. 4 % in intracoronary group), better recovery of exercise capacity and more pronounced decrease in neurohumoral activation in this patient population . Whether higher stem cell retention rates translate to additional survival benefit in patients with DCMP remains to be further explored. Currently ongoing REMEDIUM trial (Repetitive intramyocardial CD34+ cell therapy in dilated cardiomyopathy; NCT 02248532) is evaluating the potential benefits of repetitive transendocardial CD34+ stem cell injactions in DCMP patients and the results are expected to be available by the end of 2017.
Mesenchymal Stem Cells (MSC)
MSC represent a part of nonhematopoetic cell compartment of the bone marrow and have been reported to differentiate into cardiomyocytes  and endothelial cells  in vitro. The potential advantage of these cells over other stem cell types studied to date is that they are immunoprivileged and thus do not cause the activation of immune response and allosensibilization, which enables them to be used in an allogeneic setting.
Two clinical trials explored MSC in DCMP. Butler et al. evaluated in a placebo controlled crossover trial the safety and efficacy of intravenously applied allogeneic MSC (1,5 x 106/kg) in 22 DCMP patients. Although at 90 days no improvement of LVEF was observed the data suggested better exercise capacity and quality of life after stem cell treatment . The larger POSEIDON-DCM trial (Randomized comparison of allogeneic versus autologous mesenchymal stem cells for nonischemic dilated cardiomyopathy; NCT 01392625) compared the safety and afficiency of transendocardial injection of autologous and allogeneis MSC. The authors demonstrated significantly better response to allogeneic MSC compared to autologous MSC. The former were associated with better improvement in LVEF (8 % vs. 4 %), decrease in myocardial inflammation, increase in patient exercise capacity and quality of life . Several factors might account for greater efficacy of allogeneic MSC and include MCS donor age (mean age in the allogeneic MSC group was about 50 % of the autologous MSC group) and the possible adverse impact of systemic proinflammatory milieu of heart failure on autologous MSC . Despite encouraging results of study of Butler at al. and POSEIDON-DCM larger trials are warranted to confirm these data. Currently ongoing phase III trial DREAM-HF (Efficacy and safety of allogeneic mesenchymal precursor cells (Rexlemestrocel-L) for the treatment of heart failure; NCT 02032004), focusing on chronic heart failure of both ischemic and non-ischemic etiology, will hopefully corroborate these data and firmly establish the allogeneic MSC therapy for the treatment of DCMP.
Cardiosphere-Derived Cells (CDC)
CDC represent a heterogeneous mix of cells, derived from myocardial biopsy tissue and comprise of cells that express hematopoetical as well as mesenchymal antigens . In vitro CDC were shown to differentiate in cardiomyocytes, and animal data suggested intracoronary injections of CDCs may promote myocardial repair . There are currently no complete clinical trials of CDC in DCMP. The ongoing DYNAMIC trial (The dilated cardiomyopathy intervention with allogeneic myocardIally-regenerative cells; NCT unavailable) is aiming to evaluate a safety of allogeneic CDC in DCMP patients and the results of the trial are expected in 2020.
Autologous vs. Allogeneic Stem Cells
In recent years using allogeneic stem cell products became of a significant interest in the field of heart failure management. One obvious reason for this shift in clinical practice is the standardization of stem cell products and the generation of »off the shelve« product where heart failure patients can be treated without prior bone marrow stimulation and/or aspiration which is invasive, costly and logistically quite cumbersome.
The other, clinically more significant, reason is that sicker heart failure patients generate less stem cells that are also less potent [8, 9, 10]. Although underlying mechanisms remain incompletely explained heart failure-associated systemic inflammatory response is currently believed to be the the main culprit [9, 10]. Several studies, published in the last decade, also demonstrated that circulating EPC and CD34+ cells are reduced in the presence of cardiovascular risk factors (CVRF) such as arterial hypertension, diabetes and hyperlipidemia . Additionally nonmodifiable CVRF such as male gender and age were also associated with lower circulating EPC count . It was further shown that clustering of these risk factors leads to progressive reduction in circulating stem cell count .
It was also established that in comparisson to patients with ishemic heart disease, patients with DCMP express significantly less myocardial homing factors, further reducing the efficiency of endogenous repair mechanisms of the myocardium in this patient population .
To overcome these limitations of autologous stem cell therapy allogeneic stem cells were recently explored [23, 29, 30]. Initial clinical experience is encouraging as allogeneic stem cells were demontrated to be safe and feasible and may thus represent an important step towards standardiztion of stem cell therapy in patients with ischemic and nonischemic heart failure. Currently larger trials are needed to firmly establish efficiency of allogeneic stem cell therapy in patients with heart failure.
The ability of the damaged myocardium to attract circulating stem cells is fundamental to myocardial repair. It is currently suggested that acutely injured myocardium generates cytokine-mediated signals for mobilization of stem cell pool from bone marrow to peripheral circulation. Afterwards, these circulating bone marrow-derived cells follow a SDF-1 cytokine gradient that enables them to home to the damaged regions of the myocardium . However, in the setting of chronic heart failure, these stem cell recruitment and homing stimuli are significantly decreased, insufficient to significantly mitigate the myocardial injury, and actually favor retention of stem cells in the bone marrov or in the peripheral circulation . This limitation can be overcome by exogenous delivery of stem cells to the injured myocardium.
To date, no consensus has been reached with regards to optimal mode of stem cell delivery to the failing myocardium. Intramyocardial (IM), and intracoronary (IC) have mainly been used in the clinical settings . By far the most widely clinically used approach is IC stem cell delivery . While being demonstrated to be simple, cheap and safe, it has two major limitations: first, stem cells cannot reach sites of poorly perfused myocardium, thereby limiting the feasibility of this approach in patients with chronic ischemic HF who tipically have diffuse and advanced coronary artery disease. Secondly, using larger cell types and/or higher stem cell doses may cause microemboli and thus an obstruction of target coronary artery causing additional ischemic damage to the already failing myocardium. IM route is the most aggressive among the approaches for stem cell therapy. However, especially when used in combination with electroanatomical mapping, it provides the most direct and precise stem cell delivery to the target myocardium. Although associated with higher costs and requiring additional training it was demonstrated to be safe and efficient yielding significantly higher myocardial cell retention rates than IC stem cell delivery .
EFFICACY OF STEM CELL THERAPY IN NON-ISCHEMIC HEART FAILURE
Studies of stem cell therapy in patients with DCMP have demonstrated signs of improvement in LVEF (Figure 1) and exercise capacity [12, 13, 15, 17, 23]. Whether these improvements translate to improved outcomes (hospital readmissions, survival) of this patient cohort, however, remains largely unaswered.
Our unpublished RECORD registry (Registry of cell therapy in non-ischemic dilated cardiomyopathy; NCT02445534) data on 148 chronic HF patients suggest stem cell therapy may lead to reduced hospital readmissions due to worsening heart failure. Within one year after stem cell therapy we have observed a significant decrease in heart-failure related hospital readmissions when compared to the 1-year interval before cell therapy (0,8±0,8 admissions/year before cell therapy and 0,5±0,9 admissions/year after cell therapy; P=0.007).
The longest follow-up of DCMP patients receiving stem cells published to date showed that after 5 years patients who received CD34+ stem cells had significantly lower cardiovascular mortality being 14 % in stem cell group (55 patients) and 35 % in controls (55 patients). (Figure 2) Additionally pump failure was found to be significantly lower in the treatment arm (5 % vs. 18 %, P=0.03), but not sudden cardiac death (9 % vs. 16 %, P=0.39) .
Although these results are based on small single-center data and need to be confirmed in larger trials they still offer an encouraging signal that stem cell therapy on top of optimal medical management further improves long-term prognosis of DCMP patients.
IIn summary, the data of currently available clinical trials of stem cell therapy in DCMP have shown promising results regarding the improvement of LVEF, patients‘ functional capacitiy and quality of life. This is in stark contrast to the clinical trials of stem cell therapy in ischemic heart disease that failed to consistently demonstrate the beneficial effect of this treatment modality, thus making DCMP apparently more inviting target for stem cell therapy. Given the heterogeneity of clinical characteristics of patients with DCMP it may be difficult to define a single »fit-all« stem cell therapeutic approach. Future stem cell strategies should aim for more personalized therapeutic approach by establishing optimal stem cell type or their combination, dose, and delivery method for an individual patient adjusted for underlying cause of heart failure and stage of the disease.
All authors declarethat there is no conflict of interest regarding the publication of this paper.
- Roger VL, Go AS, Lloyd-Jones DM, et al. Heart disease and stroke statistics—2017 update: A report from the american heart association. Circulation. 2017;135:e1–e458.
- Ponikowski P, Voors AA, Anker SD, Bueno H, Cleland JG, Coats AJ, Falk V, González-Juanatey JR, Harjola VP, Jankowska EA, Jessup M, Linde C, Nihoyannopoulos P, Parissis JT, Pieske B, Riley JP, Rosano GM, Ruilope LM, Ruschitzka F, Rutten FH, van der Meer P; Authors/Task Force Members; Document Reviewers. 2016 ESC Guidelines for the diagnosis and treatment of acute and chronic heart failure: The Task Force for the diagnosis and treatment of acute and chronic heart failure of the European Society of Cardiology (ESC). Developed with the special contribution of the Heart Failure Association (HFA) of the ESC. Eur J Heart Fail. 2016;18(8):891–975.
- Orlic D, Kajstura J, Chimenti S, et al. Bone marrow cells regenerate infarcted myocardium. Nature. 2001;410:701–705.
- Lund LH, Edwards LB, Dipchand AI, Goldfarb S, Kucheryavaya AY, Levvey BJ, Meiser B, Rossano JW, Yusen RD, Stehlik J; The Registry of the International Society for Heart and Lung Transplantation: Thirty-third Adult Heart Transplantation Report-2016; Focus Theme: Primary Diagnostic Indications for Transplant. J Heart Lung Transplant. 2016;35(10):1158–1169.
- Richardson P, McKenna W, Bristow M, Maisch B, Mautner B, O‘Connell J, Olsen E, Thiene G, Goodwin J, Gyarfas I, Martin I, Nordet P. Report of the 1995 World Health Organization/International Society and Federation of Cardiology Task Force on the Definition and Classification of cardiomyopathies. Circulation. 1996;93(5):841–2.
- Nakahara S, Tung R, Ramirez RJ, Michowitz Y, Vaseghi M, Buch E, Gima J, Wiener I, Mahajan A, Boyle NG, Shivkumar K. Characterization of the arrhythmogenic substrate in ischemic and nonischemic cardiomyopathy implications for catheter ablation of hemodynamically unstable ventricular tachycardia. J Am Coll Cardiol. 2010;55(21):2355–65.
- Roura S1, Bayes-Genis A. Vascular dysfunction in idiopathic dilated cardiomyopathy. Nat Rev Cardiol. 2009;6(9):590–8.
- Schäfer R, Abraham D, Paulus P, Blumer R, Grimm M, Wojta J, Aharinejad S. Impaired VE-cadherin/beta-catenin expression mediates endothelial cell degeneration in dilated cardiomyopathy. Circulation. 2003;108(13):1585–91.
- Theiss HD, David R, Engelmann MG, Barth A, Schotten K, Naebauer M, Reichart B,Steinbeck G, Franz WM. Circulation of CD341 progenitor cell populations in patients with idiopathic dilated and ischaemic cardiomyopathy (DCM and ICM). European Heart Journal. 2007;28:1258–1264.
- Valgimigli, M. et al. CD34+ and ePCs in patients with various degrees of congestive heart failure. Circulation. 2004;110:1209–1212.
- Blau HM, Brazelton TR, Weimann JM. The evolving concept of a stem cell: entity or function? Cell. 2001;105(7):829–41.
- Fischer-Rasokat U, Assmus B, Seeger FH, et al. A pilot trial to assess potential effects of selective intracoronary bone marrow-derived progenitor cell infusion in patients with nonischemic dilated cardiomyopathy: Final 1-year results of the transplantation of progenitor cells and functional regeneration enhancement pilot trial in patients with nonischemic dilated cardiomyopathy. Circ Heart Fail. 2009;2:417–423.
- Seth S, Narang R, Bhargava B, et al.Percutaneous intracoronary cellular cardiomyoplasty for nonischemic cardiomyopathy: Clinical and histopathological results: The first-in-man ABCD (autologous bone marrow cells in dilated cardiomyopathy) trial. J Am Coll Cardiol. 2006;48:2350–2351.
- Bocchi EA, Bacal F, Guimarães G, et al. Granulocyte-colony stimulating factor or granulocyte-colony stimulating factor associated to stem cell intracoronary infusion effects in non ischemic refractory heart failure. Int J Cardiol. 2010;138(1):94–7.
- Hamshere S, Arnous S, Choudhury T, Choudry F, Mozid A, Yeo C, Barrett C, Saunders N, Gulati A, Knight C, Locca D, Davies C, Cowie MR, Prasad S, Parmar M, Agrawal S, Jones D, Martin J, McKenna W, Mathur A. Randomized trial of combination cytokine and adult autologous bone marrow progenitor cell administration in patients with non-ischaemic dilated cardiomyopathy: the REGENERATE-DCM clinical trial. Eur Heart J. 2015;36(44):3061–9.
- Rehman J, Li J, Orschell CM, March KL. Peripheral blood “endothelial progenitor cells” are derived from monocyte/macrophages and secrete angiogenic growth factors. Circulation. 2003;107:1164–1169.
- Vrtovec B, Poglajen G, Sever M, et al. Effects of intracoronary stem cell transplantation in patients with dilated cardiomyopathy. J Card Fail. 2011;17:272–281.
- Vrtovec B, Poglajen G, Lezaic L, et al. Effects of intracoronary CD34+ stem cell transplantation in nonischemic dilated cardiomyopathy patients: 5-year follow-up. Circ Res. 2013;112(1):165–73.
- Vrtovec B, Poglajen G, Lezaic L, Sever M, Socan A, Domanovic D, Cernelc P, Torre-Amione G, Haddad F, Wu JC. Comparison of transendocardial and intracoronary CD34+ cell transplantation in patients with nonischemic dilated cardiomyopathy. Circulation. 2013;128(11 Suppl 1):S42–9
- Toma C, Pittenger MF, Cahill KS, et al. Human mesenchymal stem cellsdifferentiate to a cardiomyocyte phenotype in the adult murine heart. Circulation. 2002;105:93–98.
- Reyes M, Dudek A, Jahagirdar B, et al. Origin of endothelialprogenitors in human postnatal bone marrow. J Clin Invest. 2002;109:337–346.
- Butler J, Epstein SE, Greene SJ, Quyyumi AA, Sikora S, Kim RJ, Anderson AS, Wilcox JE, Tankovich NI, Lipinski MJ, Ko YA, Margulies KB, Cole RT, Skopicki HA, Gheorghiade M. Intravenous Allogeneic Mesenchymal Stem Cells for Nonischemic Cardiomyopathy: Safety and Efficacy Results of a Phase II-A Randomized Trial. Circ Res. 2017;120(2):332–340.
- Hare JM, DiFede DL, Rieger AC, Florea V, Landin AM, El-Khorazaty J, Khan A, Mushtaq M, Lowery MH, Byrnes JJ, Hendel RC, Cohen MG, Alfonso CE, Valasaki K, Pujol MV, Golpanian S, Ghersin E, Fishman JE, Pattany P, Gomes SA, Delgado C, Miki R, Abuzeid F, Vidro-Casiano M, Premer C, Medina A, Porras V, Hatzistergos KE, Anderson E, Mendizabal A, Mitrani R, Heldman AW. Randomized Comparison of Allogeneic Versus Autologous Mesenchymal Stem Cells for Nonischemic Dilated Cardiomyopathy: POSEIDON-DCM Trial. J Am Coll Cardiol. 2017;69(5):526–537.
- Messina E, De Angelis L, Frati G, et al. Isolation and expansionof adult cardiac stem cells from human and murine heart. Circ Res. 2004;95:911–921.
- Johnston PV, Sasano T, Mills K, et al. Engraftment, differentiation, and functional benefits of autologous cardiosphere-derived cells in porcine ischemic cardiomyopathy. Circulation. 2009;120:1075–1083.
- Fadini GP, Losordo D, Dimmeler S. Critical reevaluation of endothelial progenitor cell phenotypes for therapeutic and diagnostic use. Circ Res. 2012 Feb 17;110(4):624–37.
- Heiss C, Keymel S, Niesler U, Ziemann J, Kelm M, Kalka C. Impaired progenitor cell activity in age-related endothelial dysfunction. J Am Coll Cardiol. 2005;45:1441–1448.
- Vasa M, Fichtlscherer S, Aicher A, Adler K, Urbich C, Martin H, Zeiher AM, Dimmeler S. Number and migratory activity of circulating endothelial progenitor cells inversely correlate with risk factors for coronary artery disease. Circ Res. 2001;89:E1–E7.
- Perin EC, Borow KM, Silva GV, DeMaria AN, Marroquin OC, Huang PP, Traverse JH, Krum H, Skerrett D, Zheng Y, Willerson JT, Itescu S, Henry TD. A Phase II Dose-Escalation Study of Allogeneic Mesenchymal Precursor Cells in Patients With Ischemic or Nonischemic Heart Failure. Circ Res. 2015;117(6):576–84.
- Kastrup J, Haack-Sørensen M, Juhl M, Harary Søndergaard R, Follin B, Drozd Lund L, Mønsted Johansen E, Ali Qayyum A, Bruun Mathiasen A, Jørgensen E, Helqvist S, Jørgen Elberg J, Bruunsgaard H, Ekblond ACryopreserved Off-the-Shelf Allogeneic Adipose-Derived Stromal Cells for Therapy in Patients with Ischemic Heart Disease and Heart Failure-A Safety Study. Stem Cells Transl Med. 2017;6(11):1963–1971.
- Fazel S, Cimini M, Chen L, et al.Cardioprotective c-kit+ cells are from the bone marrow and regulate the myocardial balance of angiogenic cytokines. J Clin Invest. 2006;116(7):1865–77.
- Golpanian S, Schulman IH, Ebert RF, Heldman AW, DiFede DL, Yang PC, Wu JC, Bolli R, Perin EC, Moyé L, Simari RD, Wolf A, Hare JM; Cardiovascular Cell Therapy Research Network. Concise Review: Review and Perspective of Cell Dosage and Routes of Administration From Preclinical and Clinical Studies of Stem Cell Therapy for Heart Disease. Stem Cells Transl Med. 2016;5(2):186–91.
- Sheng CC1, Zhou L, Hao J. Current stem cell delivery methods for myocardial repair. Biomed Res Int. 2013;2013:547902.