Search

Stem cell research has expanded at an exponential rate, but its therapeutic applications have progressed much more slowly. Currently, the research focuses on understanding embryonic, adult, and inducible pluripotent stem cells. Translation of adult stem cell research has established a definitive benefit that is greater than that of the current standard of care in the field of cardiovascular medicine. The future of stem cell research and therapy will continue to provide novel avenues of diagnostics, therapeutics, and tissue regeneration. Here we discuss a brief history of stem cell research as it transitioned from the 20th to the 21st century. We address lessons learned in the first decade of the new millennium that could help guide others to translate research into therapy across disciplines. Finally, we highlight future goals and challenges that must be overcome and offer some perspective on the bright future of stem cell research and therapy. Key words: stem cells, regenerative medicine, history, future, clinical. La recherche sur les cellules souches avance d'une facon exponentielle, mais ses applications therapeutiques ont progresse beaucoup plus lentement. Actuellement, la recherche se concentre sur la comprehension des cellules souches tant embryonnaires qu' adultes et pluripotentes inductibles. La recherche translationnelle sur les cellules souches adultes a montre un benefice definitif qui est superieur a celui des standards de soins actuels dans le domaine de la medecine cardiovasculaire. L'avenir de la recherche et de la therapie avec les cellules souches continuera d'ouvrir de nouvelles avenues dans le diagnostic, la therapeutique et la regeneration tissulaire. Nous presentons ici un bref historique de la recherche sur les cellules souches et discutons de sa transition du 20ieme au 21ieme siecle. Nous traitons des lecons apprises au cours de la premiere decennie du nouveau millenaire qui pourraient aider a guider les autres a transferer leur recherche vers la therapie, a travers les disciplines. Finalement, nous mettons l'accent sur les objectifs et les defis future qui devront etre surmontes, et nous offrons une certaine perspective du brillant avenir de la recherche et de la therapie avec les cellules souches. Mots-cles : cellules souches, medecine regeneratrice, histoire, avenir, clinique. [Traduit par la Redaction], Stem cells--a history brief The goal of this review is to discuss the origins of stem cell research and recent studies and to provide a future perspective, particularly for young [...]

The mechanisms for the beneficial impact of bone marrow cell (BMC) therapy after myocardial infarction (MI) are ill defined. We hypothesized that the implanted cells improve function by attenuating post-MI inflammation and repair. In mice, 3 x [10.sup.5] fresh BMCs were implanted immediately after coronary ligation. Cardiac function was evaluated over time. Inflammatory cytokines and cells were measured, and their impacts on the (myo)fibroblastic repair response, angiogenesis, and scar formation were determined. All differences below had P values of cell transplantation; myocardial infarction; cell therapy; myofibroblasts

We hypothesized that pretreatment of an infarcted heart by mechanical transmyocardial revascularization (TMR) before transplantation of bone marrow cells (BMCs) or BMC-expressing angiogenic growth factors would increase transplanted BMC survival and enhance myocardial repair. Female Lewis rats underwent coronary ligation 3 wk before creation of 10 needle TMR channels (3 groups) or no TMR (3 groups), followed by transplantation of 3 x [10.sup.6] male donor BMCs, BMC transfected with vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and insulin-like growth factor-1 (IGF-1) (BMC + VBI), or medium alone. At 1, 3, and 7 days, we evaluated transplanted cell survival, vascular densities, and left ventricular (LV) function (N = 4 per group x 6 groups x 3 time points). At 3 days, vascular densities in the scar were increased by TMR + BMC + VBI and by BMC + VBI (P < 0.05), and at 7 days, vascular densities were greatest in rats receiving TMR + BMC + VBI (P < 0.05). Transplanted cell survival at 3 and 7 days was increased by TMR and by BMC + VBI. Combined therapy with TMR + BMC + VBI resulted in the greatest cell survival at 3 days (P < 0.05) versus BMC. After 7 days, LV ejection fraction (LVEF) was lowest in rats receiving neither BMC nor TMR and greatest in rats receiving TMR + BMC + VBI (P = 0.004). We concluded that mechanical pretreatment of infarcted myocardium by TMR enhances the effect of subsequent cell-based gene therapy on transplanted cell survival, angiogenesis, and LV function. Scar pretreatment with TMR combined with cell-based multigene therapy may maximize myocardial repair. cell transplantation; angiogenesis

Characteristically, uterine myometrial cells (MCs) are proliferative, inducing angiogenesis within the female reproductive organ. We evaluated whether MCs implanted into myocardium could also induce angiogenesis and restore heart function after injury. MCs were isolated from the adult rat uterus and cultured for three studies: 1) Intracellular VEGF levels were measured in MCs cultured with progesterone ([10.sup.-11], [10.sup.-9], and [10.sup.-7] M) (n = 6 tests per group). 2) Blood vessel density was evaluated 8 days after MCs (3 x [10.sup.6] or 6 x [10.sup.6]), smooth muscle cells (SMCs), or endothelial cells (n = 6 rats per group) were injected with matrigel into the subcutaneous tissue of adult rats. 3) MCs, SMCs (5 x [10.sup.6]/rat), or media were injected into a transmural scar 3 wk after cryoinjury in rat hearts (n = 12 rats per group), and heart function, blood vessel density, and myocardial scar size and thickness were evaluated 5 wk later. In study 1, cultured MCs expressed VEGF, with levels significantly (P < 0.05) upregulated by progesterone at an optimal dose of [10.sup.-11] M. In study 2, MCs injected into the subcutaneous tissue with matrigel induced significantly more blood vessels, especially large-diameter vessels, than did SMCs or endothelial cells (P < 0.01 for all groups). This angiogenic effect was greatest (P < 0.01) at higher doses of MCs and was enhanced by progesterone ([10.sup.-11] M). In study 3, MCs implanted into the injured myocardium increased blood vessel density at the implant area, reduced scar size, and improved cardiac function relative to SMCs and media. Overall, MCs induced angiogenesis in vitro and in vivo, prevented cardiac remodeling, and improved heart functional recovery after cardiac injury. cell transplantation; heart failure; ischemic cardiomyopathy; angiogenic effect; heart function

Cell transplantation prevents cardiac dysfunction after myocardial infarction. However, because most implanted cells are lost to ischemia and apoptosis, the benefits of cell transplantation on heart function could be improved by increasing cell survival. To examine this possibility, male Lewis rat aortic smooth muscle cells (SMCs; 4 x [10.sup.6]) were pretreated with antiapoptotic Bcl-2 gene transfection or heat shock and then implanted into the infarcted myocardium of anesthetized, syngenic female rats (n = 23 per group). On the first day after transplantation, apoptotic SMCs were quantified by using transferase-mediated dUTP nick-end labeling staining. On days 7 and 28, grafted cell survival was quantified by using real-time PCR, and heart function was assessed with the use of echocardiography and the Langendorffapparatus. SMCs given antiapoptotic pretreatments exhibited improvements in each measure relative to controls. Apoptosis was reduced in Bcl-2-treated cells relative to all other groups (P < 0.05), whereas survival (P < 0.01) was increased. Heat shock also significantly decreased apoptosis and increased survival relative to control groups (P < 0.05 for group effect), although these effects were less pronounced than in the Bcl-2-treated group. Further, scar areas were reduced in both Bcl-2- and heat shock-treated groups relative to controls (P < 0.05), and fractional area change and cardiac function were greater (P < 0.05 for both measures). These results indicate that antiapoptosis pretreatments reduced grafted SMC loss after transplantation and enhanced grafted cell survival and ventricular function, which was directly related (r = 0.72; P = 0.002) to the number of surviving engrafted cells. cell therapy; Bcl-2; heat shock; ventricular modulation; angiogenesis doi:10.1152/ajpheart.00155.2006

Clinical trials of bone marrow stem/progenitor cell therapy after myocardial infarction (MI) have shown promising results, but the mechanism of benefit is unclear. We examined the nature of endogenous myocardial [...]

We evaluated the impact of donor age on the efficacy of myocardial cellular therapy for ischemic cardiomyopathy. Characteristics of smooth muscle cells (SMC), bone marrow stromal cells (MSCs), and skeletal muscle cells (SKMCs) from young, adult, and old rats were compared in vitro. Three weeks after coronary ligation, 3.5 million SMCs (n = 11) or MSCs (n = 9) from old syngenic rats or culture medium (n = 6) were injected into the ischemic region. Five weeks after implantation, cardiac function was assessed by echocardiography and the Langendorff apparatus. In the in vitro study, the numbers and proliferation of MSCs from fresh bone marrow and SKMCs from fresh tissue but not SMCs were markedly diminished in old animals (P < 0.05 both groups). SKMCs from old animals did not reach confluence. After treatment with 5-azacytidine (azacitidine), the myogenic potential of old MSCs was decreased compared with young MSCs. In the in vivo study, both SMC and MSC transplantation induced significant angiogenesis compared with media injections (P < 0.05 both groups). Transplantation of SMCs but not MSCs prevented scar thinning (P = 0.03) and improved ejection fraction and fractional shortening (P < 0.05). Load-independent indices of cardiac function in a Langendorff preparation confirmed improved function in the aged SMC group (P = 0.01) but not in the MSC group compared with the control group. In conclusion, donor age adversely impacts the efficacy of cellular therapy for myocardial regeneration and is cell-type dependent. SMCs from old donors retain their ability to improve cardiac function after implantation into ischemic myocardium. myocardial infarction; aging

Decreased levels of tetrahydrobiopterin (BH4), an absolute cofactor for nitric oxide synthase (NOS), lead to uncoupling of NOS into a superoxide v. nitric oxide producing enzyme, and it is this uncoupling that links it to the development of vascular disease. However, the effects of in vivo deficiency of BH4 on neointimal formation after vascular injury have not been previously investigated. Hph-1 mice, which display 90% deficiency in guanine triphosphate cyclohydrolase I, the rate limiting enzyme in BH4 synthesis, were used. Hph-1 and wild-type mice, treated with either vehicle or BH4 (n = 15 per group), were subjected to wire-induced femoral artery injury, and NOS expression and activity, inflammation, cell proliferation, superoxide production, and neointimal formation were assessed. The major form of NOS expressed over vessel wall after vascular injury was endothelial NOS. Hph-1 mice exhibited lower NOS activity (2.8 [+ or -] 0.3 vs. 4.5 [+ or -] 0.4 pmol/min/mg protein, P < 0.01), and higher aortic superoxide content (5.2 [+ or -] 2.0 x [10.sup.5] cpm vs. 1.6 [+ or -] 0.7 X [10.sup.5] cpm, P < 0.01) compared with wild-type controls, indicating uncoupling of NOS. Treatment of hph-1 mice with BH4 significantly increased NOS activity (from 2.8 [+ or -] 0.3 to 4.1 [+ or -] 0.4 pmol * [min.sup.-1] * mg [protein.sup.-1], P < 0.05), and attenuated superoxide production (from 5.2 [+ or -] 2.0 X [10.sup.5] cpm to 0.8 [+ or -] 0.7 X [10.sup.5] cpm, P < 0.05). Hph-1 mice also had higher inflammatory reactions and more cell proliferation after vascular injury. Furthermore, hph-1 mice responded by a marked increase in neointimal formation at 4 wk after vascular injury, compared with wild-type controls (intima:media ratio: 4.5 [+ or -] 0.5 vs. wild-type 0.7 [+ or -] 0.1, P < 0.001). Treatment of hph-1 mice with BH4 prevented vascular injury-induced increase in neointimal formation (intima:media ratio: 1.4 [+ or -] 0.1 vs. hph-l, P < 0.001). Treatment had no effect on wild-type controls. In summary, we describe, for the first time, that in vivo BH4 deficiency facilitates neointimal formation after vascular injury. Modulation of BH4 bioavailability is an important therapeutic target for restenosis. restenosis, superoxide; nitric oxide synthase

The functional benefit of cell transplantation after a myocardial infarction is diminished by early cell losses. IGF-1 enhances cell proliferation and survival. We hypothesized that IGF-1-transfected smooth muscle cells (SMCs) would enhance cell survival and improve engraftment after cell transplantation. The IGF-1 gene was transfected into male SMCs and compared with SMCs transfected with a plasmid vector (vector control) and nontransfected SMCs (cell control). IGF-1 mRNA (n = 10/group) and protein levels (n = 6/group) were higher (P < 0.05 for all groups) at 3, 7, and 14 days compared with controls. VEGF was also increased in parallel to enhanced IGF-1 expression. IGF-1-transfected cells demonstrated greater cell proliferation, stimulated angiogenesis, and decreased caspase-3 activity after simulated ischemia and reperfusion (P < 0.05 for all groups compared with vector or cell controls). A uniform left ventricular injury was produced in female rats using a cryoprobe. Three weeks later, 2 x [10.sup.6] cells from three groups were implanted into the scar. One week later, IGF-1-transfected SMCs had increased myocardial IGF-1 and VEGF levels, increased [Bcl.sub.2] expression, limited cell apoptosis, and enhanced vessel formation in the myocardial scar compared with the two control groups (P < 0.05 for all groups). The proportion of SMCs surviving in the implanted region was greater (P < 0.05) in the IGF-1-transfected group than in the vector or cell controls. Gene enhancement with IGF-1 improved donor cell proliferation, survival, and engraftment after cell transplantation, perhaps mediated by enhanced angiogenesis and reduced apoptosis. insulin-like growth factor-1; gene therapy; myocardial infarction; apoptosis

In the failing heart, an imbalance in matrix metalloproteinases (MMPs) and their biological regulators, the tissue inhibitors of MMPs (TIMPs), may result in cardiac dilatation from matrix degradation. We hypothesized that a reduction of myocardial TIMP-3 is associated with adverse matrix remodeling in both human and experimental heart failure. Cardiomyopathic hamsters at age 15 wk (normal), 25 wk (compensated stage), and 35 wk (overt failure) were compared with age-matched normal controls. MMP activity (gelatinase bioassay) was increased in cardiomyopathic hearts (P = 0.03) and peaked during the transition to overt heart failure. TIMP-3 content (immunoblot) was decreased compared with normal controls (74 [+ or -] 5% at 25 wk, 69 [+ or -] 10% at 35 wk; P = 0.001) and its reduction was associated with increased MMP activity (r = -0.6; P = 0.004). TIMP-1 increased progressively (P = 0.001), whereas TIMP-2, TIMP-4, and MMP protein levels were unchanged. Myocardial collagen (hydroxyproline content) increased with time during the progression to end-stage cardiac failure (P < 0.0001). Collagen synthesis ([[sup.14]C]proline uptake) was elevated in cardiomyopathy at 15 and 25 wk (P < 0.05). The collagen cross-linking ratio (insoluble:soluble collagen) was reduced (P = 0.003) as the left ventricle dilated. By confocal microscopy restricted to viable myocardium, collagen content was reduced (P = 0.04) with fragmentation (P < 0.0001) and thinning (P = 0.003) of perimysial collagen fibers. Similarly, patients with end-stage congestive heart failure (n = 7) compared with nonfailing controls (n = 2) had elevated gelatinase MMP activity (P = 0.02) associated with isolated reductions in TIMP-3 (55 [+ or -] 5% of normal; P = 0.003). Reductions of TIMP-3 parallel adverse matrix remodeling in the cardiomyopathic hamster and the failing human heart. TIMP-3 may contribute to the regulation of myocardial remodeling and its reduction may promote a transition from compensated to end-stage congestive heart failure. tissue inhibitor of matrix metalloproteinases

Protective effects of L-arginine were evaluated in a human ventricular heart cell model of low-volume anoxia and reoxygenation independent of alternate cell types. Cell cultures were subjected to 90 min of low-volume anoxia and 30 min of reoxygenation. L-Arginine (0-5.0 mM) was administered during the preanoxic period or the reoxygenation phase. Nitric oxide (NO) production, NO synthase (NOS) activity, cGMP levels, and cellular injury were assessed. To evaluate the effects of the L-arginine on cell signaling, the effects of the NOS antagonist [N.sup.G]-nitro-L-arginine methyl ester, NO donor S-nitroso-N-acetyl-penicillamine, guanylate cyclase inhibitor methylene blue, cGMP analog 8-bromo-cGMP, and ATP-sensitive [K.sup.+] channel antagonist glibenclamide were examined. Our data indicate that low-volume anoxia and reoxygenation increased NOS activity and facilitated the conversion of L-arginine to NO, which provided protection against cellular injury in a dose-dependent fashion. In addition, L-arginine cardioprotection was achieved by the activation of guanylate cyclase, leading to increased cGMP levels in human heart cells. This action involves a glibenclamide-sensitive, NO-cGMP-dependent pathway. ventricular myocytes; cardiac surgery; nitric oxide

The effect of chronically low oxygen tension on mitochondrial respiratory chain, citrate synthase and pyruvate dehydrogenase complex was investigated. In addition, the postoperative increase in lactate and decreased ATP in the myocardium as well as the high incidence of low-output failure with restoration of normal oxygen tension after a technically successful corrective cardiac surgery were examined. Results showed that hypoxia affects mitochondrial metabolism through acute and chronic adaptive mechanisms.

The role of adenosine and protein kinase C (PKC) bioactivity in promoting the myocardial protective effects of ischemic preconditioning was analyzed in monolayer cultures of human pediatric myocytes. Simulated ischemia in monolayer cultures of human pediatric myocytes indicated the role of myocyte adenosine secretions in exerting an endogenously derived form of protection through binding to sarcolemmal adenosine receptors. Furthermore, the cardioprotective effects of ischemic preconditioning involved the activation of protein kinase C by adenosine.

Stimulation of myocardial glutathione peroxidase (GPx) activity before surgery reduces the affinity of myocardium to oxyradical damage. Cells with greater phospholipase activity undergo more membrane damage. Concomitant administration of antioxidant with a phospholipase inhibitor attenuates oxyradical-induced injury to myocardial lipid membranes.