GENOMICS AND CELLULAR THERAPY: Successful Mobilization of Peripheral Blood Stem Cells by Use of Granulocyte-Colony Stimulating F

There is increasing evidence that the liberation of stem cells by use of granulocyte-colony stimulating factor (G-CSF) with or without their transcoronary transplantation is feasible and can improve cardiac function in humans after acute myocardial infarction (AMI).^1–3 However, patients with severe hemodynamic deterioration due to extensive loss of contractile tissue after AMI have not been enrolled in stem cell programs up to now. We report on the case of a patient with acute anterior wall myocardial infarction who suffered from cardiogenic shock despite successful primary percutaneous coronary intervention (PCI). After hemodynamic stabilization, pharmacological propagation of peripheral blood stem cells (PBSC) with G-CSF was initiated. Apheresis and transcoronary transplantation of the PBSC was performed 20 days after AMI. Case Report. A 37-year-old male was hospitalized after cardiopulmonary resuscitation and defibrillation for ventricular fibrillation. At admission the patient was mechanically ventilated and presented with a blood pressure of 90/60 mmHg and a sinus tachycardia of 130 beats per minute. As the electrocardiogram displayed signs of ongoing transmural ischemia of the left anterior wall, it was decided to perform primary PCI. After intravenous administration of enoxaparin, aspirin and abciximab and recanalization of the vessel with a guidewire, a 2.75 x 33 mm sirolimus-eluting stent (Cypher^®, Cordis Corp., Miami, Florida) was successfully implanted into the infarct-related left anterior descending artery (LAD) (Figures 1 and 2). Due to sustained hemodynamic instability, intra-aortic balloon counterpulsation was initiated and maintained for 48 hours. Mechanical ventilation and intravenous administration of catecholamines had to be continued for 4 days after the PCI procedure. In view of the long delay of 9 hours between symptom onset and recanalization of the LAD, the high maximum serum CK-MB concentration of 859 U/l, and extensive left ventricular akinesis with an ejection fraction of approximate 35% on echocardiography, the patient was offered the opportunity to be enrolled in a nonrandomized feasibility study that evaluated intracoronary infusion of PBSC after primary PCI for AMI. Having achieved written informed consent, pharmacological stimulation with subcutaneous injections of filgastrim, a G-CSF (Neupogen^®, Amgen, Thousand Oaks, California) was initiated on day 15 after primary PCI. The daily dose of 480 µg was divided into two applications. After 5 days of G-CSF therapy, 13 CD34+ cells/microlitre peripheral blood with a CD34+ cell/leukocyte ratio of 1.1% were measured. On day 20 after AMI, a highly concentrated mononuclear cell suspension was produced with COBE spectra^® apheresis (Gambro BCT, Lakewood, Colorado), and subsequent direct injection of the PBSC into the IRCA was performed via an over-the-wire angioplasty balloon catheter (Maverick^®, Boston Scientific Corp., Natick, Massachusetts), which was moderately inflated inside the stent. During a continuous inflation time of 3 minutes, 3 ml of PBSC suspension were slowly injected through the lumen of the catheter. The procedure was repeated twice after an interval of another 3 minutes with the balloon deflated (Figures 3 and 4). The infused suspension of 9 mL contained 9.6 x 10E6 CD34+ cells. Control angiography after balloon catheter retraction demonstrated unimpeded antegrade blood flow and the patient’s left ventricular ejection fraction (LVEF), as determined by ventriculography, was 49%. The postinterventional course was uncomplicated. On day 23 after AMI, single-photon emission computed tomography (SPECT) was performed immediately and 4 hours after ergometric treadmill exercise with thallium 201-chloride injection at peak stress. The calculated dimension of the myocardial scar (defined as a combined defect in stress-rest pattern and analyzed by standardized SPECT bull’s eye views) was 73% of the area supplied by the LAD. Before hospital discharge on day 26 after AMI, treatment with a beta-blocker was initiated in addition to aspirin and clopidogrel. At a 6-month follow up, the patient was in New York Heart Association Class I. Coronary angiography demonstrated a normal angiogram and no binary restenosis of the LAD. The LVEF obtained by ventriculography was 53%. Ventriculographic quantification using the centerline method according to Sheehan et al⁴ demonstrated an increase of systolic function in the infarct region. The dimension of the scar, calculated by control SPECT, had decreased to 63% of the area supplied by the LAD. Discussion Despite early interventional treatment, mortality in patients after AMI complicated by cardiogenic shock remains high.^5,6 Though several recently published clinical studies report sustained improvement of ventricular performance after AMI and subsequent G-CSF therapy, with or without transplantation of stem cells, patients with hemodynamic deterioration due to excessive loss of contractile tissue who would probably profit the most from this kind of therapy have not been included in these programs up to now.^1–3,7 This fact may instead be explained by study designs with fixed intervals between AMI and cell transplantation or strict hemodynamic inclusion criteria than by suspected uselessness or complications in this population. To our knowledge, this is the first report of a patient with transcoronary transplantation of G-SCF mobilized hematopoietic stem cells after AMI complicated by cardiogenic shock. Since we performed an open-label, nonrandomized feasibility study, the patient was able to be treated and followed beyond our actual protocol, despite prolonged hemodynamic instability and thus delayed cell transfer. Therapeutic cell transplantation after AMI via the harvest of hematopoietic stem cells by bone marrow aspiration as well as by processing venous blood has been described.7–10 We decided to collect PBSC from peripheral blood and aimed to gain a maximum of cells by means of G-CSF-induced liberation and subsequent apheresis. Experience in the use of G-CSF in patients with acute coronary syndrome is limited and safety issues are particularly controversial. Hill et al reported 2 cases of AMI and 1 cardiac death during G-CSF therapy in 12 patients with intractable angina,¹¹ and Zbinden et al observed 2 acute coronary occlusions in 14 patients treated with granulocyte-macrophage-colony stimulating factor before elective PCI.¹² However, two recently published trials did not report thrombotic events following sole application of G-CSF after primary stenting for AMI.^2,3 Regarding these observations, it appears to be important that G-CSF therapy is not started in the presence of vulnerable or ruptured plaques, but rather after having successfully sealed the culprit vessel segment with a stent. We demonstrated that mobilization of sufficient numbers of PBSC with G-CSF is also feasible and safe in a patient shortly after PCI for AMI complicated by cardiogenic shock. Following our protocol for G-CSF administration, the number of transplanted CD34+ cells was comparable to that achieved by other groups.^7–10 In our patient, transcoronary PBSC transplantation was performed without complications, and control coronary angiography revealed no binary restenosis after 6 months. Following AMI, catheter-based infusion of stem cells into the infarct-related coronary artery has been shown to be feasible and safe.^1,7–10,13 Though no increase in the in-stent restenosis rate has been reported after sole G-CSF therapy,^2,3 transcoronary cell transplantation, especially when combined with G-CSF therapy, seems to imply an increased risk of in-stent restenosis.^1,7,13 Whether this risk can be reduced by the use of drug-eluting stents, as was the case in our patient, clearly needs further assessment. The improvement in LVEF (from 49% to 53%) between PBSC transplantation and 6-month follow up was caused by an increase in systolic function in the infarct region and was comparable to the mean increase in LVEF observed after transplantation of bone marrow-derived cells in other studies.^1,7–10,13 The long duration of chest pain (9 hours) and the notable increase in LVEF during the first 2 weeks after AMI in our patient provide evidence that the improvement of myocardial contractility between discharge and follow up may be attributed to PBSC transplantation. Previous studies on revascularization in AMI have demonstrated that sustained LVEF improvement can only be achieved if unimpeded blood flow can be reestablished within the first 4 hours after symptom onset, and that recovery of stunned myocardium takes place primarily during the first days after ischemia.^14–17 The reduction of nonperfused myocardium detected by thallium-201-SPECT provides additional evidence that the infarcted myocardium and its border zone were positively influenced by PBSC transplantation. In conclusion, transcoronary transplantation of G-CSF-mobilized PBSC was able to be performed without acute and long-term complications in a patient following AMI and cardiogenic shock. Whether cell therapy has the potential to provide additional benefit to these severely ill patients can only be determined by randomized studies.

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