Diabetes is a risk factor for worse outcomes following acute myocardial infarction (AMI). In this study, we tested the hypothesis that SDF-1:CXCR4 expression is compromised in post-AMI in diabetes, and that reversal of this defect can reverse the adverse effects of diabetes. Mesenchymal stem cells (MSC) isolated from green fluorescent protein (GFP) transgenic mice (control MSC) were induced to overexpress stromal cell-derived factor-1 (SDF-1). SDF-1 expression in control MSC and SDF-1-overexpressing MSC (SDF-1:MSC) were quantified using enzyme-linked immunosorbent assay (ELISA). AMI was induced on db/db and control mice. Mice were randomly selected to receive infusion of control MSC, SDF-1:MSC, or saline into the border zone after AMI. Serial echocardiography was used to assess cardiac function. SDF-1 and CXCR4 mRNA expression in the infarct zone of db/db mice and control mice were quantified. Compared to control mice, SDF-1 levels were decreased 82%, 91%, and 45% at baseline, 1 day and 3 days post-AMI in db/db mice, respectively. CXCR4 levels are increased 233% at baseline and 54% 5 days post-AMI in db/db mice. Administration of control MSC led to a significant improvement in ejection fraction (EF) in control mice but not in db/db mice 21 days after AMI. In contrast, administration of SDF-1:MSC produced a significant improvement in EF in both control mice and db/db mice 21 days after AMI. The SDF-1:CXCR4 axis is compromised in diabetes, which appears to augment the deleterious consequences of AMI. Over-express of SDF-1 expression in diabetes rescues cardiac function post AMI. Our results suggest that modulation of SDF-1 may improve post-AMI cardiac repair in diabetes. Stem Cells Translational Medicine 2018;7:115-124.

Transplantation of adult stem cells into myocardial tissue after acute myocardial infarction (AMI), has been shown to improve tissue recovery and prevent progression to ischemic cardiomyopathy. Studies suggest that the effects of mesenchymal stem cells (MSC) are due to paracrine factors released by MSC, as the benefits of MSC can be achieved through delivery of conditioned media (CM) alone. We previously demonstrated that downregulation of Dab2 enhances MSC cardiac protein expression and improves cardiac function after AMI following MSC engraftment. In order to define the molecular mechanisms that regulate MSC secretome, we analyzed gene arrays in MSC following downregulation of Dab2 via TGFβ1 pretreatment or transfection with Dab2:siRNA or miR‐145. We identified 23 genes whose expressions were significantly changed in all three conditions. Among these genes, we have initially focused our validation and functional work on calcium/calmodulin‐dependent protein kinase kinase‐1 (CAMKK1). We quantified the effects of CAMKK1 overexpression in MSC following injection of CM after AMI. Injections of CM from MSC with CAMKK1 over‐expression correlated with an increase in vascular density (CAMKK1 CM: 2,794.95 ± 44.2 versus Control: 1,290.69 ± 2.8 vessels/mm2) and decreased scar formation (CAMKK1 CM 50% ± 3.2% versus Control: 28% ± 1.4%), as well as improved cardiac function. Direct overexpression of CAMKK1 in infarcted tissue using a CAMKK1‐encoding plasmid significantly improved ejection fraction (CAMKK1: 83.2% ± 5.4% versus saline: 51.7% ± 5.8%. Baseline: 91.3% ± 4.3%) and decreased infarct size after AMI. Our data identify a novel role for CAMKK1 as regulator of the MSC secretome and demonstrate that direct overexpression of CAMKK1 in infarcted cardiac tissue, results in therapeutic beneficial effects. Stem Cells Translational Medicine 2017;6:1759–1766

Introduction: Diabetes is associated with a defect in stem cell homing due to blunted SDF-1 signaling. We investigated the role of the SDF-1:CXCR4 axis in diabetic cardiomyopathy (DCM). Hypothesis:...

OBJECTIVE:Fecal incontinence reduces the quality of life of many women but has no long-term cure. Research on mesenchymal stem cell (MSC)-based therapies has shown promising results. The primary aim of this study was to evaluate functional recovery after treatment with MSCs in two animal models of anal sphincter injury. METHODS:Seventy virgin female rats received a sphincterotomy (SP) to model episiotomy, a pudendal nerve crush (PNC) to model the nerve injuries of childbirth, a sham SP, or a sham PNC. Anal sphincter pressures and electromyography (EMG) were recorded after injury but before treatment and 10 days after injury. Twenty-four hours after injury, each animal received either 0.2 ml saline or 2 million MSCs labelled with green fluorescing protein (GFP) suspended in 0.2 ml saline, either intravenously (IV) into the tail vein or intramuscularly (IM) into the anal sphincter. RESULTS:MSCs delivered IV after SP resulted in a significant increase in resting anal sphincter pressure and peak pressure, as well as anal sphincter EMG amplitude and frequency 10 days after injury. MSCs delivered IM after SP resulted in a significant increase in resting anal sphincter pressure and anal sphincter EMG frequency but not amplitude. There was no improvement in anal sphincter pressure or EMG with in animals receiving MSCs after PNC. GFP-labelled cells were not found near the external anal sphincter in MSC-treated animals after SP. CONCLUSION:MSC treatment resulted in significant improvement in anal pressures after SP but not after PNC, suggesting that MSCs could be utilized to facilitate recovery after anal sphincter injury.

Mesenchymal stem cells (MSCs) have been shown to improve cardiac electrophysiology when administered in the setting of acute myocardial infarction. However, the electrophysiological phenotype of MSCs in situ is not clear. We hypothesize that MSCs delivered intramyocardially to cryoinjured myocardium can engraft, but will not actively generate, action potentials. Cryoinjury-induced scar was created on the left ventricular epicardial surface of adult rat hearts. Within 30 min, hearts were injected with saline (sham, n = 11) or bone marrow-derived MSCs (2 × 10(6)) labeled with 1,1'-dioctadecyl-3,3,3,3'-tetramethylindocarbocyanine percholate (DiI; n = 16). At 3 wk, optical mapping and cell isolation were used to measure optical action potentials and calcium transients, respectively. Histological analysis confirmed subepicardial scar thickness and the presence of DiI-positive cells that express connexin-43. Optical action potential amplitude within the scar at MSC-positive sites (53.8 ± 14.3%) was larger compared with sites devoid of MSCs (35.3 ± 14.2%, P < 0.05) and sites within the scar of shams (33.5 ± 6.9%, P < 0.05). Evidence of simultaneous action potential upstroke, the loss of action potential activity following ablation of adjacent viable myocardium, and no rapid calcium transient response in isolated DiI+ cells suggest that the electrophysiological influence of engrafted MSCs is electrotonic. MSCs can engraft when directly injected into a cryoinjury and are associated with evidence of action potential activity. However, our results suggest that this activity is not due to generation of action potentials, but rather passive influence coupled from neighboring viable myocardium.

The coronary collateral circulation is critically important as an adaptation of the heart to prevent the damage from ischemic insults. In their native state, collaterals in the heart would be classified as part of the microcirculation, existing as arterial-arterial anastomotic connections in the range of 30 to 100 μM in diameter. However, these vessels also show a propensity to remodel into components of the macrocirculation and can become arteries larger than 1000 μM in diameter. This process of outward remodeling is critically important in the adaptation of the heart to ischemia because the resistance to blood flow is inversely related to the fourth power of the diameter of the vessel. Thus, an expansion of a vessel from 100 to 1000 μM would reduce resistance (in this part of the circuit) to a negligible amount and enable delivery of flow to the region at risk. Our goal in this review is to highlight the voids in understanding this adaptation to ischemia-the growth of the coronary collateral circulation. In doing so we discuss the controversies and unknown aspects of the causal factors that stimulate growth of the collateral circulation, the role of genetics, and the role of endogenous stem and progenitor cells in the context of the normal, physiological situation and under more pathological conditions of ischemic heart disease or with some of the underlying risk factors, e.g., diabetes. The major conclusion of this review is that there are many gaps in our knowledge of coronary collateral growth and this knowledge is critical before the potential of stimulating collateralization in the hearts of patients can be realized. This article is part of a Special Issue entitled "Coronary Blood Flow".

The effect of wnt/β‐catenin signalling in the response to acute myocardial infarction (AMI) remains controversial. The membrane receptor adaptor protein Disabled‐2 (Dab2) is a tumour suppressor protein and has a critical role in stem cell specification. We recently demonstrated that down‐regulation of Dab2 regulates cardiac protein expression and wnt/β‐catenin activity in mesenchymal stem cells (MSC) in response to transforming growth factor‐β1 (TGF‐β1). Although Dab2 expression has been shown to have effects in stem cells and tumour suppression, the molecular mechanisms regulating this expression are still undefined. We identified putative binding sites for miR‐145 in the 3′‐UTR of Dab2. In MSC in culture, we observed that TGF‐β1 treatment led to rapid and sustained up‐regulation of pri–miR‐145. Through gain and loss of function studies we demonstrate that miR‐145 up‐regulation was required for the down‐regulation of Dab2 and increased β‐catenin activity in response to TGF‐β1. To begin to define how Dab2 might regulate wnt/β‐catenin in the heart following AMI, we quantified myocardial Dab2 as a function of time after left anterior descending ligation. There was no significant Dab2 expression in sham‐operated myocardium. Following AMI, Dab2 levels were rapidly up‐regulated in cardiac myocytes in the infarct border zone. The increase in cardiac myocyte Dab2 expression correlated with the rapid and sustained down‐regulation of myocardial pri–miR‐145 expression following AMI. Our data demonstrate a novel and critical role for miR‐145 expression as a regulator of Dab2 expression and β‐catenin activity in response to TGF‐β1 and hypoxia.

The field of cardiovascular regenerative medicine has made significant strides over the past decade. Clinical trials have demonstrated benefit in acute myocardial infarction ( AMI) and chronic heart failure (CHF). As the field has matured, it has defined novel biology and invented an array of therapeutic strategies that are currently under development. In this brief review, we attempt to conceptualize the knowledge to date as well as examine how this knowledge has been translated to various therapeutic strategies.

Adult mesenchymal stem cells (MSCs) have been shown to spontaneously express cardiac proteins (CP) in vitro and to improve cardiac function after transplantation into experimentally induced acute myocardial infarction (AMI). However, if these effects are the result of MSC cardiac differentiation or a mere cooperative cellular interaction is a matter of active debate. Additionally, the molecular mechanisms involved in CP expression by adult stem cells in vitro and its possible benefit for cardiac regeneration and improved function remain unclear. Here we show that although MSCs effectively engraft in AMI tissue, this engraftment leads to downregulation of CP expression in the implanted MSCs. We also found that pretransplantation cardiac specification of MSCs by exposure of the cells to transforming growth factor beta 1 (TGF-β1) led to sustained MSC CP expression without altering engraftment efficiency. This increase in CP expression was associated with greater improvement in cardiac function 1 and 4 weeks after AMI with TGF-β1-pretreated MSCs. We discovered that the TGF-β1-enhanced cardiac potential of MSCs was mediated by downregulation of disabled-2 (Dab2) expression, suggesting an inverse correlation between Dab2 levels and CP expression/cardiac functional improvement after MSC engraftment. Our investigations further demonstrate that loss of Dab2 expression was sufficient to induce MSC CP expression and improve cardiac function after MSC engraftment after AMI. In summary, we define a novel role for the TGF-β1 receptor adaptor protein Dab2 as a regulator of CP expression in MSCs and its potential as a molecular target for the enhancement of stem cell cardiac specification for transplantation therapies.

HomeCirculation ResearchVol. 106, No. 10Searching for Understanding With the Cellular Lining of Life Free AccessEditorialPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessEditorialPDF/EPUBSearching for Understanding With the Cellular Lining of Life Marc S. Penn and Maritza E. Mayorga Marc S. PennMarc S. Penn From the Skirball Laboratory for Cardiovascular Cellular Therapeutics (M.S.P., M.E.M.), Department of Stem Cell Biology and Regenerative Medicine (M.S.P., M.E.M.), and Department of Cardiovascular Medicine (M.S.P.), Heart and Vascular Institute, Cleveland Clinic, Ohio. Search for more papers by this author and Maritza E. MayorgaMaritza E. Mayorga From the Skirball Laboratory for Cardiovascular Cellular Therapeutics (M.S.P., M.E.M.), Department of Stem Cell Biology and Regenerative Medicine (M.S.P., M.E.M.), and Department of Cardiovascular Medicine (M.S.P.), Heart and Vascular Institute, Cleveland Clinic, Ohio. Search for more papers by this author Originally published28 May 2010https://doi.org/10.1161/CIRCRESAHA.110.221499Circulation Research. 2010;106:1554–1556Stem cell therapy for the prevention and treatment of myocardial dysfunction in response to ischemic injury has progressed from preclinical models to clinical populations in relatively rapid fashion. Whereas some have argued the progress is too rapid because of the lack of a defined mechanism and the identification of an optimal cell type, others have suggested that the potential efficacy, combined with the apparent safety and increasing prevalence of chronic heart disease, requires that we move forward in clinical populations.1In general, adult stem cell populations have lacked the ability to differentiate into cardiac myocytes that beat spontaneously, suggesting that the improvements seen in preclinical and clinical studies using these stem cell populations, including mesenchymal stem cells (MSCs),2,3 bone marrow mononuclear stem cells,4,5 multipotent adult progenitor cells,6 hematopoietic stem cells,7 and others, are not attributable to replacement of damaged myocardium with new contractile tissue but rather to the release of paracrine factors that induce myocardial repair. With that said, how these paracrine factors lead to improved cardiac function, especially at time remote from acute ischemic injury, remains unclear.Finally, whether there is the potential for an “off-the-shelf” cell product that can be implemented in an allogeneic strategy that will allow for the availability of therapy at any time and, in particular, when the patient presents with an acute ischemic event is still an open question. Two cell populations, MSCs and multipotent adult progenitor cells, are currently undergoing clinical study in allogeneic strategies; however, the mechanism associated with the immunoprivileged state of these cells and whether this immunoprivilege with extend to cardiac differentiation remain important unknowns.In this issue of the Circulation Research, Tsuji et al present interesting data that address many of these questions.8 In this report, the authors focus on the human amniotic membrane as a source of mesenchymal stem cells. They hypothesize that MSCs from the membrane, which are known to have the ability to transdifferentiate into multiple cells types, could yield cardiac myocytes, and, by virtue of their role in maintaining the fetus, cells from the membrane could have immunomodulatory properties.Tsuji et al demonstrate that MSCs isolated from different human amniotic membrane-derived mesenchymal cells (hAMCs) can expand in culture with 20 to 30 population doublings. hAMCs are similar to MSCs in that they are CD90+, CD105+, CD34−, and CD117−. The authors further observe that that the hAMCs at baseline exhibit significant expression of oct4 and cardiac proteins including cardiac troponin, but after coculture with murine fetal cardiac myocytes, there is a broader expression of cardiac proteins and downregulation of oct4. The authors nicely demonstrate that the cardiac myocytes generated from hAMCs have pacemaker like activity and cardiac specific action potentials. Interestingly, the authors further demonstrate that the transdifferentiation in coculture does not require hAMC contact.The studies in the article by Tsuji et al progress to demonstrate that hAMC transplantation into the infarct border zone of immunocompetent and immunoincompetent rats 2 weeks after acute myocardial infarction results in the presence of hAMCs 4 weeks later, suggesting that in a xenogenic transplant model hAMCs are not rejected. Immunofluorescent studies further demonstrate that the surviving hAMCs have differentiated into cardiac myocytes and appear to have intercalated within surviving cardiac myocytes within the infarct border zone.Because the hAMCs are derived from the amniotic sack, Tsuji et al investigate the immunomodulatory pathways activated during fetal development and are able to demonstrate that the survival of hAMCs in the immunocompetent xenogenic model is associated with an increase in human leukocyte antigen (HLA)-G expression, low expression of major histocompatibility complex (MHC) I, and, ultimately, the activation of FOXP3+ regulatory T cells. Perhaps not surprisingly, the immunoprivilege of the hAMCs is time-dependent. Initially, the cells appear to survive because of the combination of lack of MHC I expression, which blocks T cell–mediated cell loss, and upregulation of HLA-G, which inhibits natural killer cell activity. Because differentiated hAMCs do not express HLA-G, the long-term survival of the hAMC cardiac myocytes in the xenogenic model is hypothesized to be attributable to the activation of the FOXP3 regulatory T cells that inhibit hAMCs mediated T-cell destruction. Interleukin 10 and progesterone are shown to increase HLA-G expression and hAMCs derived cardiac myocyte number in vivo; however, whether these observations are attributable to increased hAMC differentiation or enhanced survival appears to be in question, although the latter seems more likely. With that said, it is interesting to note that the secretion of interleukin 10 has also been shown to be critical for the benefits observed in association with bone marrow mononuclear cells.9Tsuji et al demonstrate that injection of ≈1 to 2 million hAMCs 2 weeks after acute myocardial infarction leads to improvement in cardiac function, whereas the untreated hearts continue to decline in function, resulting in a ≈10% absolute increase in fractional shortening 2 weeks after cell transplantation (4 weeks after acute myocardial infarction).In this study, Tsuji et al convincingly demonstrate that the hAMCs can differentiate into cardiac myocytes and that, even after differentiation, these cells survive in vivo. Yet one must admit that the ultimate mechanism resulting in the increase in cardiac function remains elusive. Laser confocal microscopy of the hearts 2 weeks after transplantation of green fluorescent protein (GFP)+ hAMCs demonstrates the presence of GFP+ cardiac myocytes, but these cells are scattered throughout the infarct border zone, intercalated in between native cardiac myocytes that survive the infarct. There is also a modest but significant decrease in the area of myocardial scar in response to hAMC engraftment. Notably lacking in these images is the presence of sheets or volumes of new cardiac myocytes replacing the injured myocardium, suggesting the lack of true regeneration of the transmural contractile tissue lost because ischemic injury.Ultimately then, if replacement of the scar with contractile tissue does not occur, what is the mechanism of benefit and how might we be able to achieve true regeneration, particularly at a time that is remote from acute myocardial infarction, when simply improving cardiac myocyte survival is not a sufficient or pervasive mechanism? Taking the later issue first, it would seem likely that the replacement of scar with contractile tissue will require the implementation of scaffolding on which contractile networks can be grown. At least in the beginning, it would appear that this scaffold may need to be implanted using a surgical approach. Although this seems like a worthy approach, the recent findings demonstrating the lack of benefit of surgical ventricular remodeling in the STICH trial needs to be acknowledged.10With respect to the mechanism of benefit, the preponderance of the data would suggest that the benefit is associated with optimal remodeling of the ventricle independent of the regeneration of cardiac myocytes.8 More specifically, improvement in the viability of the infarct border zone, the site of the weakest link in the chain. This is not a revolutionary concept, but one that is at times forgotten when those in the field turn to counting cells and debating phenotype, instead of focusing on the biology and physiology at hand. In an organ like the kidney or liver, distributed systems with discrete functional units, perhaps it is all about the number of cells and functional units. The heart, with its interconnect contractile network, however, is not unlike a chain in that it can only be as strong as its weakest link.It is interesting to note that in this study by Tsuji et al, the authors did not observe an increase in vascular density as is commonly seen in the majority,2,4,11–13 although not all14 of the preclinical cell therapy studies to date. The lack of increase in vascular density following the transplantation of hAMCs could suggest that intercalation of functional contractile cells within the infarct border zone can lead to improvement in cardiac remodeling perhaps by modifying the workload of the surviving cardiac myocytes (Figure). Conversely, cells or paracrine factors that increase vascular density but do not increase the number of contractile cells could improve cardiac function by improving the metabolic performance of the surviving cardiac myocytes (Figure). Ultimately, the same mechanism is in play with both of these strategies: improved functional performance of the infarct border zone leads to improved left ventricular remodeling and contractile performance. Download figureDownload PowerPointFigure. The figure attempts to conceptually represent how vascular growth or the intercalation of cardiac protein expressing cells within the border zone could both lead to the recruitment of contractile work of surviving cardiac myocytes and improve cardiac function and left ventricular remodeling.A, Schematic diagram of 2 potential mechanisms associated with recruitment of hibernating border zone cardiac myocytes. B, Vasculogenesis could lead to improved blood flow and oxygenation of the hibernating cells, rendering them functional. C, Cardiac protein–expressing cells could intercalate within injured myocytes, decreasing hibernating cardiac myocyte workload and thus recruiting the hibernating cells to generate contractile work.In support of this concept is a prior study from our laboratory in which we focused on the importance of remodeling the infarct border zone. In this study, we delivered GATA4 to the cardiac myocytes in the infarct border zone 1 month after acute myocardial infarction using a chimeric cell penetrating peptide strategy.15 The focal delivery of GATA4 to the border zone led to cardiac myocyte hypertrophy of the border zone cardiac myocytes and no change in the vascular density. This local hypertrophy led to an improvement in cardiac strain in the infarct border zone and global remodeling of the heart in the absence of the generation of new contractile tissue.15 This global remodeling led to improved strain in the noninfarct zone, ultimately improving cardiac function in the absence of any evidence of contractile activity in the infarct zone. The preclinical and clinical data to date, including this important study by Tsuji et al, support the concept that further understanding the biology and physiology of the infarct border zone, along with strategies designed to augment its function, is what will ultimately lead to improvement in patient outcomes.In summary, Tsuji et al should be congratulated for their careful work, which has brought forward a cell type that may offer the real potential for off-the-shelf cardiac myocyte–based therapy. Their findings further add to our understanding of the mechanisms associated with immunoprivilege, which is critical as we move forward with allogeneic cell strategies. Finally, their study further demonstrates that the real benefit associated with stem cell therapy remains elusive and we should remain open minded as to the strategies that could lead to improved outcomes in clinical populations. Table 1. Non-standard Abbreviations and AcronymsGFPgreen fluorescent proteinhAMChuman amniotic membrane-derived mesenchymal cellHLAhuman leukocyte antigenMHCmajor histocompatibility complexMSCmesenchymal stem cellThe opinions expressed in this editorial are not necessarily those of the editors or of the American Heart Association.Sources of FundingFunded by the Skirball Foundation and the American Heart Association, Greater Rivers Affiliate (to M.E.M.).DisclosuresNone.FootnotesCorrespondence to Marc S. Penn, MD, PhD, Skirball Laboratory for Cardiovascular Cellular Therapeutics, Departments of Cardiovascular Medicine and Stem Cell Biology, J2-131, 9500 Euclid Ave, Cleveland, OH 44195. E-mail [email protected] References 1 Penn MS, Topol E. The challenge for stem cell therapy. In: Penn MS, ed. Stem Cells and Myocardial Regeneration. Totowa: Humana Press; 2007: 1–8.Google Scholar2 Zhang M, Mal N, Kiedrowski M, Chacko M, Askari AT, Popovic ZB, Koc ON, Penn MS. Sdf-1 expression by mesenchymal stem cells results in trophic support of cardiac myocytes after myocardial infarction. FASEB J. 2007; 21: 3197–3207.CrossrefMedlineGoogle Scholar3 Hare J, Traverse J, Henry T, Dib N, Strumpf R, Schulman S, Gerstenblith G, DeMaria A, Denktas A, Gammon R, Hermiller J, Reisman M, Schaer G, Sherman W. A randomized, double-blind, placebo-controlled, dose-escalation study of intravenous adult human mesenchymal stem cells (prochymal) following acute myocardial infarction. J Am Coll Cardiol. 2009; 54: 2277–2286.CrossrefMedlineGoogle Scholar4 Orlic D, Kajstura J, Chimenti S, Jakoniuk I, Anderson SM, Li B, Pickel J, McKay R, Nadal-Ginard B, Bodine DM, Leri A, Anversa P. Bone marrow cells regenerate infarcted myocardium. Nature. 2001; 410: 701–705.CrossrefMedlineGoogle Scholar5 Schachinger V, Erbs S, Elsasser A, Haberbosch W, Hambrecht R, Holschermann H, Yu J, Corti R, Mathey DG, Hamm CW, Suselbeck T, Assmus B, Tonn T, Dimmeler S, Zeiher AM. Intracoronary bone marrow-derived progenitor cells in acute myocardial infarction. N Engl J Med. 2006; 355: 1210–1221.CrossrefMedlineGoogle Scholar6 Van't HW, Mal N, Huang Y, Zhang M, Popovic Z, Forudi F, Deans R, Penn MS. Direct delivery of syngeneic and allogeneic large-scale expanded multipotent adult progenitor cells improves cardiac function after myocardial infarct. Cytotherapy. 2007; 9: 477–487.CrossrefMedlineGoogle Scholar7 Kocher AA, Schuster MD, Szabolcs MJ, Takuma S, Burkhoff D, Wang J, Homma S, Edwards NM, Itescu S. Neovascularization of ischemic myocardium by human bone-marrow-derived angioblasts prevents cardiomyocyte apoptosis, reduces remodeling and improves cardiac function. Nat Med. 2001; 7: 430–436.CrossrefMedlineGoogle Scholar8 Tsuji H, Miyoshi S, Ikegami Y, Hida N, Asada H, Togashi I, Suzuki J, Satake M, Nakamizo H, Tanaka M, Mori T, Segawa K, Nishiyama N, Inoue J, Makino H, Miyado K, Ogawa S, Yoshimura Y, Umezawa A. Xenografted human amniotic membrane-derived mesenchymal stem cells are immunologically tolerated and transdifferentiated into cardiomyocytes. Circ Res. 2010; 106: 1613–1623.LinkGoogle Scholar9 Burchfield JS, Iwasaki M, Koyanagi M, Urbich C, Rosenthal N, Zeiher AM, Dimmeler S. Interleukin-10 from transplanted bone marrow mononuclear cells contributes to cardiac protection after myocardial infarction. Circ Res. 2008; 103: 203–211.LinkGoogle Scholar10 Jones RH, Velazquez EJ, Michler RE, Sopko G, Oh JK, O'Connor CM, Hill JA, Menicanti L, Sadowski Z, Desvigne-Nickens P, Rouleau JL, Lee KL. Coronary bypass surgery with or without surgical ventricular reconstruction. N Engl J Med. 2009; 360: 1705–1717.CrossrefMedlineGoogle Scholar11 Tang YL, Zhu W, Cheng M, Chen L, Zhang J, Sun T, Kishore R, Phillips MI, Losordo DW, Qin G. Hypoxic preconditioning enhances the benefit of cardiac progenitor-cell therapy for treatment of myocardial infarction by inducing cxcr4 expression. Circ Res. 2009; 104: 1209–1216.LinkGoogle Scholar12 Ziebart T, Yoon CH, Trepels T, Wietelmann A, Braun T, Kiessling F, Stein S, Grez M, Ihling C, Muhly-Reinholz M, Carmona G, Urbich C, Zeiher AM, Dimmeler S. Sustained persistence of transplanted proangiogenic cells contributes to neovascularization and cardiac function after ischemia. Circ Res. 2008; 103: 1327–1334.LinkGoogle Scholar13 Deglurkar I, Mal N, Mills WR, Popovic ZB, McCarthy P, Blackstone EH, laurita KR, Penn MS. Mechanical and electrical effects of cell-based gene therapy for ischemic cardiomyopathy are independent. Hum Gene Ther. 2006; 17: 1144–1151.CrossrefMedlineGoogle Scholar14 Schenk S, Mal N, Finan A, Zhang M, Kiedrowski M, Popovic Z, McCarthy PM, Penn MS. Monocyte chemotactic protein-3 is a myocardial mesenchymal stem cell homing factor. Stem Cells. 2007; 25: 245–251.CrossrefMedlineGoogle Scholar15 Bian J, Popovic ZB, Benejam C, Kiedrowski M, Rodriguez LL, Penn MS. Effect of cell-based intercellular delivery of transcription factor gata4 on ischemic cardiomyopathy. Circ Res. 2007; 100: 1626–1633.LinkGoogle Scholar Previous Back to top Next FiguresReferencesRelatedDetailsCited By Nso N, Bookani K, Enoru S, Radparvar F and Gordon R (2021) The efficacy of bone marrow mononuclear stem cell transplantation in patients with non-ischemic dilated cardiomyopathy—a meta analysis, Heart Failure Reviews, 10.1007/s10741-021-10082-0, 27:3, (811-820), Online publication date: 1-May-2022. Wen Y, Ding J, Zhang B and Gao Q (2018) Bone marrow-derived mononuclear cell therapy for nonischaemic dilated cardiomyopathy-A meta-analysis, European Journal of Clinical Investigation, 10.1111/eci.12894, 48:4, (e12894), Online publication date: 1-Apr-2018. Puliafico S, Penn M and Silver K (2013) Stem Cell Therapy for Heart Disease, Journal of General Internal Medicine, 10.1007/s11606-013-2508-z, 28:10, (1353-1363), Online publication date: 1-Oct-2013. Penn M and Anwaruddin S (2012) Stem Cell Therapy for Ischemic Heart Disease Textbook of Interventional Cardiology, 10.1016/B978-1-4377-2358-8.00055-3, (745-753), . Penn M (2012) Regenerative Therapy as an Adjunct to Mechanical Support Mechanical Circulatory Support: A Companion to Braunwald's Heart Disease, 10.1016/B978-1-4160-6001-7.00018-X, (239-248), . Simioniuc A, Campan M, Lionetti V, Marinelli M, Aquaro G, Cavallini C, Valente S, Di Silvestre D, Cantoni S, Bernini F, Simi C, Pardini S, Mauri P, Neglia D, Ventura C, Pasquinelli G and Recchia F (2011) Placental stem cells pre-treated with a hyaluronan mixed ester of butyric and retinoic acid to cure infarcted pig hearts: a multimodal study, Cardiovascular Research, 10.1093/cvr/cvr018, 90:3, (546-556), Online publication date: 1-Jun-2011., Online publication date: 1-Jun-2011. De Coppi P (2010) C-kit/CD117 Cells From Amniotic Fluid and Membranes and Their Cardiomyogenic Potential, Circulation Research, 107:6, (e11-e11), Online publication date: 17-Sep-2010. Bolli P and Chaudhry H (2010) Molecular physiology of cardiac regeneration, Annals of the New York Academy of Sciences, 10.1111/j.1749-6632.2010.05814.x, 1211:1, (113-126), Online publication date: 1-Nov-2010. May 28, 2010Vol 106, Issue 10 Advertisement Article InformationMetrics https://doi.org/10.1161/CIRCRESAHA.110.221499PMID: 20508198 Originally publishedMay 28, 2010 Keywordsmultipotent adult progenitor cellsstem cell therapymesenchymal stem cellshuman amniotic membranePDF download Advertisement

Myocardial infarction (MI) is a lead cause of mortality in the Western world. Treatment of acute MI is focused on restoration of antegrade flow which inhibits further tissue loss, but does not restore function to damaged tissue. Chronic therapy for injured myocardial tissue involves medical therapy that attempts to minimize pathologic remodeling of the heart. End stage therapy for chronic heart failure (CHF) involves inotropic therapy to increase surviving cardiac myocyte function or mechanical augmentation of cardiac performance. Not until the point of heart transplantation, a limited resource at best, does therapy focus on the fundamental problem of needing to replace injured tissue with new contractile tissue. In this setting, the potential for stem cell therapy has garnered significant interest for its potential to regenerate or create new contractile cardiac tissue. While to date adult stem cell therapy in clinical trials has suggested potential benefit, there is waning belief that the approaches used to date lead to regeneration of cardiac tissue. As the literature has better defined the pathways involved in cardiac differentiation, preclinical studies have suggested that stem cell pretreatment to direct stem cell differentiation prior to stem cell transplantation may be a more efficacious strategy for inducing cardiac regeneration. Here we review the available literature on pre-transplantation conditioning of stem cells in an attempt to better understand stem cell behavior and their readiness in cell-based therapy for myocardial regeneration.

Somatostatin analogues (SAs) are potential anticancer agents. This study was designed to investigate the expression of somatostatin receptors (SSTRs) in melanoma cells and the effect of two SAs on cell proliferation and viability. Eighteen primary and metastatic human cutaneous melanoma cell lines were treated with octreotide and SOM230. Expression of SSTR1, SSTR2, SSTR3 and SSTR5 was assessed by real-time polymerase chain reaction. Proliferation, viability and cell death were assessed using standard assays. Inhibition was modelled by mixed-effect regression. Melanoma cells expressed one or more SSTR. Both SAs inhibited proliferation of most melanoma cell lines, but inhibition was < 50%. Neither SA affected cell viability or induced cell death. The results suggest that melanoma cell lines express SSTRs. The SAs investigated, under the conditions used in this study, did not, however, significantly inhibit melanoma growth or induce cell death. Novel SAs, combination therapy with SAs and their anti-angiogenic properties should be further investigated.

Superparamagnetic iron oxide (SPIO) particles have been used successfully as an intracellular contrast agent for nuclear MRI cell tracking in vivo. We present a method of detecting intracellular SPIO colloid uptake in live cells using cell magnetophoresis, with potential applications in measuring intracellular MRI contrast uptake. The method was evaluated by measuring shifts in mean and distribution of the cell magnetophoretic mobility, and the concomitant changes in population frequency of the magnetically positive cells when compared to the unmanipulated negative control. Seven different transfection agent (TA) -SPIO complexes based on dendrimer, lipid, and polyethylenimine compounds were used as test standards, in combination with 3 different cell types: mesenchymal stem cells, cardiac fibroblasts, and cultured KG-1a hematopoietic stem cells. Transfectol (TRA) -SPIO incubation resulted in the highest frequency of magnetically positive cells (>90%), and Fugene 6 (FUG) -SPIO incubation the lowest, below that when using SPIO alone. A highly regular process of cell magnetophoresis was amenable to intracellular iron mass calculations. The results were consistent in all the cell types studied and with other reports. The cell magnetophoresis depends on the presence of high-spin iron species and is therefore expected to be directly related to the cell MRI contrast level.

Cardiac fibroblasts play an essential role in the physiology of the heart. These produce extracellular matrix proteins and synthesize angiogenic and cardioprotective factors. Although fibroblasts of cardiac origin are known to be resistant to apoptosis and to remain metabolically active in situations compromising cell survival, the underlying mechanisms are unknown. Here, we report that cardiac fibroblasts were more resistant than dermal or pulmonary fibroblasts to mitochondria-dependent cell death. Cytochrome c release was blocked in cardiac fibroblasts but not in dermal fibroblasts treated with staurosporine, etoposide, serum deprivation, or simulated ischemia, precluding caspase-3 activation and DNA fragmentation. Resistance to apoptosis of cardiac fibroblasts correlated with the expression of the anti-apoptotic protein Bcl-2, whereas skin and lung fibroblasts did not express detectable levels of this protein. Bcl-xL, Bax, and Bak were expressed at similar levels in cardiac, dermal, and lung fibroblasts. In addition, the death of cardiac fibroblasts during hypoxia was not associated with the cleavage of Bid but rather with Bcl-2 disappearance, suggesting the requirement of the mitochondrial apoptotic machinery to execute death receptor-induced programmed cell death. Knockdown of bcl-2 expression by siRNA in cardiac fibroblasts increased their apoptotic response to staurosporine, serum, and glucose deprivation and to simulated ischemia. Moreover, dermal fibroblasts overexpressing Bcl-2 achieved a similar level of resistance to these stimuli as cardiac fibroblasts. Thus, our data demonstrate that Bcl-2 is an important effector of heart fibroblast resistance to apoptosis and highlight a probable mechanism for promoting survival advantage in fibroblasts of cardiac origin.

Apoptosis plays a role in cardiomyocyte death in several cardiovascular disorders. Here, we show that primary postnatal cardiomyocytes did not die upon activation of the intrinsic (cytochrome c-dependent) apoptotic pathway. Release of cytochrome c from mitochondria to the cytosol occurred, but did not activate the effector phase of apoptosis. Myocardial cells did not express apoptotic protease-activating factor-1 (Apaf-1), the allosteric activator of caspase-9 acting downstream of cytochrome c release. Forced expression of Apaf-1 restored the competence to complete the cytochrome c-induced apoptotic program and this effect was prevented by overexpression of Bcl-X(L). However, cardiomyocytes were able to enter the apoptotic program when it was initiated by activation of death receptors, as observed during serum deprivation and metabolic inhibition. Our results indicate that regulation of Apaf-1 expression may be a new regulatory mechanism developed in postmitotic cells in order to prevent irreversible commitment to die after release of cytochrome c.