Didier Blocklet

Myocardial Homing of Nonmobilized Peripheral‐Blood CD34+ Cells After Intracoronary Injection

Granulocyte– colony‐stimulating factor administered for autologous hematopoietic stem cell isolation from blood may favor restenosis in patients implanted after acute myocardial infarction (AMI). We therefore tested the isolation of peripheral‐blood CD34+ cells without mobilization in six patients with AMI. After large‐volume cytapheresis and positive CD34+ cell selection, 3.6 to 27.6 million CD34+ cells were obtained. We performed intra‐coronary implantation of these cells and recorded no restenosis or arrhythmia. We used positron emission tomography (PET) to assess myocardial‐labeled CD34+ cell homing, which accounted for 5.5% of injected cells 1 hour after implantation. In conclusion, large amounts of CD34+ cells, in the range reported in previous studies, can be obtained from nonmobilized peripheral blood. PET with [18F]‐fluorodeoxyglucose cell labeling is an efficient imaging method for homing assessment.

A new dendritic cell vaccine generated with interleukin-3 and interferon-beta induces CD8+ T cell responses against NA17-A2 tumor peptide in melanoma patients.

Dendritic cells derived from monocytes cultured in the presence of type I interferon were found to induce efficient T cell responses against tumor antigens in vitro. We vaccinated eight stage III or IV melanoma patients with dendritic cells generated with interferon-β and interleukin-3, activated by poly I: C, and pulsed with the tumor-specific antigen NA17.A2. This dendritic cell vaccine was well-tolerated with only minor and transient flu-like symptoms and inflammatory reactions at the injection sites. In most patients, isotopic imaging documented dendritic cells (DC) migration from the intradermal injection site to the draining lymph nodes. Finally, mixed lymphocyte-peptide culture under limiting dilution conditions followed by tetramer labeling indicated that three out of eight patients mounted a CD8 T cell response against the NA17.A2 antigenic peptide. We conclude that DC generated in type I-IFN represent an interesting alternative to DC generated in IL-4 and GM-CSF for cancer immunotherapy.

Myocardial homing and coronary endothelial function after autologous blood CD34+ progenitor cells intracoronary injection in the chronic phase of myocardial infarction.

Transcoronary transplantation of progenitor cells has been proposed as a novel therapy for ischemic heart failure. The primary aims were to assess the feasibility of obtaining CD34+ cells from blood without mobilization in chronic conditions and to compare homing with results reported in acute conditions. We also evaluated the effect of CD34+ on endothelial function. In 7 patients with a history of an anterior myocardial infarction (20 ± 2 months), a large amount of CD34+ (18.2 ± 3.0 × 106) were obtained and an intracoronary infusion into the left anterior descending artery via an over-the-wire balloon catheter was performed. Myocardial homing involved 3.2% ± 0.6% of injected cells. Endothelial function studied with increasing doses of bradykinin was not significantly modified after 3 months. In the treated group, compared with 5 nonrandomized control patients with a similar clinical history, the only echocardiographic significant change (2-way analysis of variance) was a decrease in end-systolic volume (P < 0.03). In conclusion, large amounts of CD34+ cells can be obtained from blood, without mobilization, in the chronic phase of myocardial infarction. As reported in the acute situation 1 hour after treatment, intracoronary infusion of CD34+ cells results in myocardial homing of a few percents of the cells. In this small group of patients, no effect of this therapy is detected on the endothelial function and only marginal changes are observed on echocardiographic parameters.

Accurate pre-operative localization of pathological parathyroid glands using 11C-methionine PET/CT.

OBJECTIVE The pre-operative technique most routinely used to localize pathological parathyroid glands (PPG), prior to minimal access surgery (MAS), relies on 99mTc-sestamibi (MIBI) scintigraphy. Positron emission tomography (PET) using the radiolabelled amino acid 11C-methionine as the tracer agent offers a technological alternative to localize PPG. In this study we evaluated the sensitivity of 11C-methionine PET/CT (MET-PET/CT) for PPG detection and the extent to which MET-PET/CT images may contribute to the planning of surgical procedures. DESIGN Thirty patients were included, 22 with primary hyperparathyroidism and eight with secondary hyperparathyroidism. Patients suspected of suffering from parathyroid hyperplasia underwent a complete surgical exploration of the neck region. In those suspected of parathyroid adenoma, surgery was limited to the presumed localization described by MET-PET/CT. To specifically address the additional benefit of the MET-PET/CT in terms of surgical planning and procedure, the surgeon classified the patients into two categories depending on the type of benefit, or the reason for the absence of benefit, occurring in each case. We also compared the sensitivity of MET-PET/CT and MIBI scintigraphy. RESULTS The total number of lesions removed was 46 (24 adenomatous and 22 hyperplastic). Globally, MET-PET/CT provided additional benefit to surgery in 15 out of 30 cases (50%). The sensitivity of 11C-methionine PET/CT and MIBI scintigraphy was respectively 92% and 95% for adenoma, and 68% and 59% for hyperplasia, on the basis of available resected lesions. CONCLUSION MET-PET/CT appears a reliable technique to guide MAS of parathyroid glands.

Lung, Gastric, and Soft Tissue Uptake of Tc-99m MDP and Ga-67 Citrate Associated with Hypercalcemia

Metastatic calcifications are associated with chronic renal failure, hyperparathyroidism, metastatic neoplasms, hypervitaminosis D, and hypercalcemia of other origins. Bone scanning agents accumulate within these extraskeletal metastatic calcifications. The authors describe two patients with hypercalcemia associated with Tc-99m MDP uptake in the lungs, stomach, and soft tissues. Ga-67 scintigraphy was also performed and showed increased uptake in the same locations as those of Tc-99m MDP, suggesting the existence of an inflammatory process. Despite adequate treatment, only partial resolution of extraskeletal uptake was observed.

Presurgical localization of abnormal parathyroid glands using a single injection of technetium-99m methoxyisobutylisonitrile: Comparison of different techniques including factor analysis of dynamic structures

Single-tracer methoxyisobutylisonitrile (MIBI) imaging is considered to be a sensitive method for the localization of abnormal parathyroid glands. The aims of this study were to determine which of the analytical techniques described for this method — visual comparison of early (15-min) and late (120-min) images, use of time-activity curves (TACs) generated on regions of interest and factor analysis of dynamic structures (FADS) — corresponds best with surgical findings, and to ascertain the potential overall contribution of presurgical scintigraphy. Fifty-five patients were studied, 34 of whom presented with primary hyperparathyroidism (HPT) and 21 with secondary HPT. After a 925 MBq injection of technetium-99m MIBI, a 40-min dynamic acquisition was performed and static images were acquired at 5, 20, 40 and 120 min using a gamma camera equipped with a pinhole collimator. The dynamic series were submitted to FADS, an attractive non-operator-dependent technique, and TACs were generated on regions of interest after the visual comparison of early and 120-minute images (15′–120′). The presumed localizations of abnormal glands were compared with a sketch drawn by the surgeon. Sensitivity was defined as the percentage of truepositive localizations and was 84.4%, 74% and 65% in adenoma and 76%, 66.6% and 45% in hyperplasia for 15′–120′, FADS and TACs, respectively. Surgical accuracy, i.e. the percentage of patients accurately and completely described, was 72%, 56% and 59% in adenoma and 53%, 30% and 22% in hyperplasia for 15′–120′, FADS and TACs, respectively. The visual comparison method scored best in all cases. FADS was found to be sensitive in cases of adenoma but was handicapped by more false-positive localizations. TACs were particular inefficient in hyperplasia. With respect to the detection of adenomas, we found a relationship between the gland weight and scintigraphic positivity. This dependence on gland weight was not found in hyperplasia. The poorer results obtained with all techniques for surgical accuracy can be explained by the need for a complete scintigraphic description of all pathological glands found by the surgeon in a patient. This study demonstrates that the 15′–120′ visual comparison method is more efficient and less cumbersome than TAC or the attractive FADS technique. However, it was less efficient than neck exploration by an experienced surgeon. Therefore, in our institution, scintigraphic studies are now only requested in selected cases of HPT, usually primary HPT and cases undergoing re-operation.

Bidirectional MHC molecule exchange between migratory and resident dendritic cells

Dendritic cells (DCs) loaded extracorporeally with antigen can be used as an adjuvant in vivo. In this work, we analyzed the migration of transferred DC and monitored the phenotype of new migrants in the draining lymph nodes. It is surprising that we found that a majority of resident DCs expressed donor MHC molecules and that a proportion of injected DCs acquired host MHC molecules. These observations suggest that a bidirectional MHC molecule exchange occurs between migratory and resident DCs, a mechanism that may amplify antigen presentation in vivo.

Therapeutic efficacy of antitumor dendritic cell vaccinations correlates with persistent Th1 responses, high intratumor CD8+ T cell recruitment and low relative regulatory T cell infiltration

Despite the increasing number of immunotherapeutic strategies for the treatment of cancer, most approaches have failed to correlate the induction of an anti-tumor immune response with therapeutic efficacy. We therefore took advantage of a successful vaccination strategy—combining dendritic cells and irradiated GM-CSF secreting tumor cells—to compare the immune response induced against 9L gliosarcoma tumors in cured rats versus those with progressively growing tumors. At the systemic level, the tumor specific cytotoxic responses were quite heterogeneous in uncured vaccinated rats, and were surprisingly often high in animals with rapidly-growing tumors. IFN-γ secretion by activated splenic T cells was more discriminative as the CD4+ T cell-mediated production was weak in uncured rats whereas high in cured ones. At the tumor level, regressing tumors were strongly infiltrated by CD8+ T cells, which demonstrated lytic capacities as high as their splenic counterparts. In contrast, progressing tumors were weakly infiltrated by T cells showing impaired cytotoxic activities. Proportionately to the T cell infiltrate, the expression of Foxp3 was increased in progressive tumors suggesting inhibition by regulatory T cells. In conclusion, the main difference between cured and uncured vaccinated animals does not depend directly upon the induction of systemic cytotoxic responses. Rather the persistence of higher CD4+ Th1 responses, a high intratumoral recruitment of functional CD8+ T cells, and a low proportion of regulatory T cells correlate with tumor rejection.

Comparative pharmacoscintigraphic and pharmacokinetic evaluation of two new formulations of inhaled insulin in type 1 diabetic patients

In this open, single-dose study, we compared the lung deposition and bioavailability of two newly developed insulin formulations for pulmonary delivery. Twelve type 1 diabetic patients were administered the two insulin products (2 U/kg b.w.), which had been radiolabelled with (99m)Tc. The formulations were either microparticles of insulin without excipients (F1) or lipid-coated insulin microparticles (F2). Lung deposition was assessed by γ-scintigraphy imaging performed immediately after administration. Bioavailability was evaluated by quantifying serum insulin levels over a period of 6 h. Lung deposition was found to be 50 ± 9% and 24 ± 8% for the F1 and F2 formulations, respectively. The insulin AUC₀₋₃₆₀ ratio of F1/F2 was 188%, which was consistent with scintigraphic imaging. The concordance between imaging and biological results suggests that the lower bioavailability of F2 is due to its lower lung deposition and not to a reduced absorption into the blood stream. Additional in vitro experiments indicated that the lower performance of F2 was most probably related to a lower disaggregation efficiency of the powder when administered at a sub-optimal flow rate. The two formulations showed interesting pharmacokinetic profiles (T(max) of 26 and 16 min for F1 and F2, respectively) that mimic the physiological insulin secretion pattern. The bioavailability of the developed formulations was within the range of other DPI insulin formulations that have reached the final stages of clinical development.

Positron emission tomography scanning in anti-neutrophil cytoplasmic antibodies-associated vasculitis

AbstractTools for evaluation of disease activity in patients with anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) include scoring clinical manifestations, determination of biochemical parameters of inflammation, and obtaining tissue biopsies. These tools, however, are sometimes inconclusive. 2-deoxy-2-[18F]-fluoro-D-glucose (FDG) positron emission tomography (PET) scans are commonly used to detect inflammatory or malignant lesions. Our objective is to explore the ability of PET scanning to assess the extent of disease activity in patients with AAV.Consecutive PET scans made between December 2006 and March 2014 in Maastricht (MUMC) and between July 2008 and June 2013 in Brussels (EUH) to assess disease activity in patients with AAV were retrospectively included. Scans were re-examined and quantitatively scored using maximum standard uptake values (SUVmax). PET findings were compared with C-reactive protein (CRP) and ANCA positivity at the time of scanning.Forty-four scans were performed in 33 patients during a period of suspected active disease. All but 2 scans showed PET-positive sites, most commonly the nasopharynx (n = 22) and the lung (n = 22). Forty-one clinically occult lesions were found, including the thyroid gland (n = 4 patients), aorta (n = 8), and bone marrow (n = 7). The amount of hotspots, but not the highest observed SUVmax value, was higher if CRP levels were elevated. Seventeen follow-up scans were made in 13 patients and showed decreased SUVmax values.FDG PET scans in AAV patients with active disease show positive findings in multiple sites of the body even when biochemical parameters are inconclusive, including sites clinically unsuspected and difficult to assess otherwise.