118: Co-transplanation of haploidentical mesenchymal stem cells to overcome graft dysfunction associated with parental haploidentical CD34 postive selected peripheral stem cell grafts

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Human Allogeneic Bone Marrow and Adipose Tissue Derived Mesenchymal Stromal Cells Induce CD8+ Cytotoxic T Cell Reactivity

INTRODUCTION: For clinical applications, Mesenchymal Stromal Cells (MSC) can be isolated from bone marrow and adipose tissue of autologous or allogeneic origin. Allogeneic cell usage has advantages but may harbor the risk of sensitization against foreign HLA. Therefore, we evaluated whether bone marrow and adipose tissue-derived MSC are capable of inducing HLA-specific alloreactivity. METHODS: MSC were isolated from healthy human Bone Marrow (BM-MSC) and adipose tissue (ASC) donors. Peripheral Blood Mononuclear Cells (PBMC) were co-cultured with HLA-AB mismatched BM-MSC or ASC precultured with or without IFNy. After isolation via FACS sorting, the educated CD8+ T effector populations were exposed for 4 hours to Europium labeled MSC of the same HLA make up as in the co-cultures or with different HLA. Lysis of MSC was determined by spectrophotometric measurement of Europium release. RESULTS: CD8+ T cells educated with BM-MSC were capable of HLA specific lysis of BM-MSC. The maximum lysis was 24% in an effector:target (E:T) ratio of 40:1. Exposure to IFNγ increased HLA-I expression on BM-MSC and increased lysis to 48%. Co-culturing of PBMC with IFNγ-stimulated BM-MSC further increased lysis to 76%. Surprisingly, lysis induced by ASC was significantly lower. CD8+ T cells educated with ASC induced a maximum lysis of 13% and CD8+ T cells educated with IFNγ-stimulated ASC of only 31%. CONCLUSION: Allogeneic BM-MSC, and to a lesser extend ASC, are capable of inducing HLA specific reactivity. These results should be taken into consideration when using allogeneic MSC for clinical therapy

Intramyocardial Injection of Autologous Bone Marrow-Derived Ex Vivo Expanded Mesenchymal Stem Cells in Acute Myocardial Infarction Patients is Feasible and Safe up to 5 Years of Follow-up

Abstract In experimental studies, mesenchymal stem cell (MSC) transplantation in acute myocardial infarction (AMI) models has been associated with enhanced neovascularization and myogenesis. Clinical data however, are scarce. Therefore, the present study evaluates the safety and feasibility of intramyocardial MSC injection in nine patients, shortly after AMI during short-term and 5-year follow-up. Periprocedural safety analysis demonstrated one transient ischemic attack. No other adverse events related to MSC treatment were observed during 5-year follow-up. Clinical events were compared to a nonrandomized control group comprising 45 matched controls. A 5-year event-free survival after MSC-treatment was comparable to controls (89 vs. 91 %, P =0.87). Echocardiographic imaging for evaluation of left ventricular function demonstrated improvements up to 5 years after MSC treatment. These findings were not significantly different when compared to controls. The present safety and feasibility study suggest that intramyocardial injection of MSC in patients shortly after AMI is feasible and safe up to 5-year follow-up

Autologous bone marrow-derived mesenchymal stromal cell treatment for refractory luminal Crohn’s disease: results of a phase I

Mesenchymal stromal cells (MSCs) are pluripotent cells that have immunosuppressive effects both in vitro and in experimental colitis. Promising results of MSC therapy have been obtained in patients with severe graft versus host disease of the gut. Our objective was to determine the safety and feasibility of autologous bone marrow derived MSC therapy in patients with refractory Crohn's disease. 10 adult patients with refractory Crohn's disease (eight females and two males) underwent bone marrow aspiration under local anaesthesia. Bone marrow MSCs were isolated and expanded ex vivo. MSCs were tested for phenotype and functionality in vitro. 9 patients received two doses of 1-2×10(6) cells/kg body weight, intravenously, 7 days apart. During follow-up, possible side effects and changes in patients' Crohn's disease activity index (CDAI) scores were monitored. Colonoscopies were performed at weeks 0 and 6, and mucosal inflammation was assessed by using the Crohn's disease endoscopic index of severity. MSCs isolated from patients with Crohn's disease showed similar morphology, phenotype and growth potential compared to MSCs from healthy donors. Importantly, immunomodulatory capacity was intact, as Crohn's disease MSCs significantly reduced peripheral blood mononuclear cell proliferation in vitro. MSC infusion was without side effects, besides a mild allergic reaction probably due to the cryopreservant DMSO in one patient. Baseline median CDAI was 326 (224-378). Three patients showed clinical response (CDAI decrease ≥70 from baseline) 6 weeks post-treatment; conversely three patients required surgery due to disease worsening. Administration of autologous bone marrow derived MSCs appears safe and feasible in the treatment of refractory Crohn's disease. No serious adverse events were detected during bone marrow harvesting and administratio

T-cell receptor excision circle and T-cell dynamics after allogeneic stem cell transplantation are related to clinical events

It is generally believed that homeostatic responses regulate T-cell recovery after peripheral stem cell transplantation (PSCT). We studied in detail immune recovery in relation to T-cell depletion and clinical events in a group of adult patients who underwent PSCT because of hematologic malignancies. Initially, significantly increased proportions of dividing naive, memory, and effector CD4(+) and CD8(+) T cells were found that readily declined, despite still very low numbers of CD4(+) and CD8(+) T cells. After PSCT, increased T-cell division rates reflected immune activation because they were associated with episodes of infectious disease and graft-versus-host disease (GVHD). T-cell receptor excision circles (TRECs) were measured to monitor thymic output of naive T cells. Mean TREC content normalized rapidly after PSCT, long before naive T-cell numbers had significantly recovered. This is compatible with the continuous thymic production of TREC(+) naive T cells and does not reflect homeostatic increases of thymic output. TREC content was decreased in patients with GVHD and infectious complications, which may be explained by the dilution of TRECs resulting from increased proliferation. Combining TREC and Ki67 analysis with repopulation kinetics led to the novel insight that recovery of TREC content and increased T-cell division during immune reconstitution after transplantation are related to clinical events rather than to homeostatic adaptation to T-cell depletion. (Blood. 2002;99:3449-3453

CCR4+ Regulatory T Cells Accumulate in the Very Elderly and Correlate With Superior 8-Year Survival

CD4(+) regulatory T cells (Tregs) are a distinct population of T cells involved in maintaining peripheral tolerance to self-antigens. Several studies have shown increased frequency and number of Tregs in the elderly. Whether such an increase has any clinical relevance has not been addressed. Here, we have analyzed circulating Tregs in 114 donors between the ages of 18 and 89 years and assessed their implications for survival of the very elderly. In line with previously published data, we observed higher proportions of Tregs in the elderly. Expression of chemokine receptor 4 (CCR4) by Tregs has been shown to characterize antigen-primed activated Tregs with immediate suppressive function. Thus we further analyzed Tregs expressing or lacking this chemokine receptor. There were more CCR4(+) and CCR4(-) Tregs in the elderly than the young. Finally, using a subset of 48 elderly donors participating in the Leiden 85-plus study we documented that people with greater median frequencies of CCR4(+) Tregs enjoyed a better 8-year survival rate than those with lower frequencies of these cells. Our data, demonstrating for the first time a positive correlation between increased frequency of Tregs and survival in the elderly, imply an increasing importance of controlling inappropriate immune responses and inflammation as we grew old

CCR4 +

CD4(+) regulatory T cells (Tregs) are a distinct population of T cells involved in maintaining peripheral tolerance to self-antigens. Several studies have shown increased frequency and number of Tregs in the elderly. Whether such an increase has any clinical relevance has not been addressed. Here, we have analyzed circulating Tregs in 114 donors between the ages of 18 and 89 years and assessed their implications for survival of the very elderly. In line with previously published data, we observed higher proportions of Tregs in the elderly. Expression of chemokine receptor 4 (CCR4) by Tregs has been shown to characterize antigen-primed activated Tregs with immediate suppressive function. Thus we further analyzed Tregs expressing or lacking this chemokine receptor. There were more CCR4(+) and CCR4(-) Tregs in the elderly than the young. Finally, using a subset of 48 elderly donors participating in the Leiden 85-plus study we documented that people with greater median frequencies of CCR4(+) Tregs enjoyed a better 8-year survival rate than those with lower frequencies of these cells. Our data, demonstrating for the first time a positive correlation between increased frequency of Tregs and survival in the elderly, imply an increasing importance of controlling inappropriate immune responses and inflammation as we grew old