Presence of osteoclast precursor cells during ex vivo expansion of bone marrow-derived mesenchymal stem cells for autologous use in cell therapy.

BACKGROUND AIMS: To obtain a cell product competent for clinical use in terms of cell dose and biologic properties, bone marrow-derived mesenchymal stem cells (MSCs) must be expanded ex vivo. METHODS: A retrospective analysis was performed of records of 76 autologous MSC products used in phase I or II clinical studies performed in a cohort of cardiovascular patients. In all cases, native MSCs present in patient bone marrow aspirates were separated and expanded ex vivo. RESULTS: The cell products were classified in two groups (A and B), according to biologic properties and expansion time (ex vivo passages) to reach the protocol-established cell dose. In group A, the population of adherent cells obtained during the expansion period (2 ± 1 passages) was composed entirely of MSCs and met the requirements of cell number and biologic features as established in the respective clinical protocol. In group B, in addition to MSCs, we observed during expansion a high proportion of ancillary cells, characterized as osteoclast precursor cells. In this case, although the biologic properties of the resulting MSC product were not affected, the yield of MSCs was significantly lower. The expansion cycles had to be increased (3 ± 1 passages). CONCLUSIONS: These results suggest that the presence of osteoclast precursor cells in bone marrow aspirates may impose a limit for the proper clinical use of ex vivo expanded autologous bone marrow-derived MSCs.

Vascular disease and stem cell therapies.

INTRODUCTION AND BACKGROUND: Peripheral vascular disease is the leading cause of limb ischemia (LI). LI is manifested by claudication, ischemic rest pain, ulcers or gangrene. It is the result of peripheral arterial disease due to atherosclerosis. Over the last decade, several centers around the world have initiated clinical trials utilizing stem cells as a treatment for this disease. SOURCES OF DATA: Published medical literature, clinical trials announced in clinical trials.gov and TCA cellular therapy experience. AREAS OF AGREEMENT: There is general agreement that stem cells are useful for LI. AREAS OF CONTROVERSY: These arise from the type of cells, dose, route of administration and methods to evaluate efficacy. GROWING POINTS: Growing evidence suggests that bone marrow derived-mesenchymal stem cells are as good as or superior to mononuclear cells, and a combination of both cell types may be even better. AREAS TIMELY FOR DEVELOPING RESEARCH: Based on current trials and publications, several promising biological products could become part of the therapeutic arsenal for LI. This may include combinations of more than one type of adult/induced pluripotent stem cells/embryonic stem cells, use of stem cells with growth factors or extracellular matrix molecules.

Effect of torcetrapib on the progression of coronary atherosclerosis.

BACKGROUND: Levels of high-density lipoprotein (HDL) cholesterol are inversely related to cardiovascular risk. Torcetrapib, a cholesteryl ester transfer protein (CETP) inhibitor, increases HDL cholesterol levels, but the functional effects associated with this mechanism remain uncertain. METHODS: A total of 1188 patients with coronary disease underwent intravascular ultrasonography. After treatment with atorvastatin to reduce levels of low-density lipoprotein (LDL) cholesterol to less than 100 mg per deciliter (2.59 mmol per liter), patients were randomly assigned to receive either atorvastatin monotherapy or atorvastatin plus 60 mg of torcetrapib daily. After 24 months, disease progression was measured by repeated intravascular ultrasonography in 910 patients (77%). RESULTS: After 24 months, as compared with atorvastatin monotherapy, the effect of torcetrapib-atorvastatin therapy was an approximate 61% relative increase in HDL cholesterol and a 20% relative decrease in LDL cholesterol, reaching a ratio of LDL cholesterol to HDL cholesterol of less than 1.0. Torcetrapib was also associated with an increase in systolic blood pressure of 4.6 mm Hg. The percent atheroma volume (the primary efficacy measure) increased by 0.19% in the atorvastatin-only group and by 0.12% in the torcetrapib-atorvastatin group (P=0.72). A secondary measure, the change in normalized atheroma volume, showed a small favorable effect for torcetrapib (P=0.02), but there was no significant difference in the change in atheroma volume for the most diseased vessel segment. CONCLUSIONS: The CETP inhibitor torcetrapib was associated with a substantial increase in HDL cholesterol and decrease in LDL cholesterol. It was also associated with an increase in blood pressure, and there was no significant decrease in the progression of coronary atherosclerosis. The lack of efficacy may be related to the mechanism of action of this drug class or to molecule-specific adverse effects. (ClinicalTrials.gov number, NCT00134173 [ClinicalTrials.gov].).

Bone marrow-derived stem/progenitor cells: their use in clinical studies for the treatment of myocardial infarction.

Over the last six years, several centres around the world have started clinical trials to investigate the utilisation of bone marrow-derived cells for myocardial infarction. Different types and numbers of cells have been used assuming they possess a potential to originate new endothelial cells and/or cardiomyocytes to repair/regenerate the ailed heart. Despite diversity in number, clinical status of subjects, route of cell administration, and criteria to evaluate efficacy, the main conclusion drawn from these clinical studies was that such therapies were safe. However, attempts to unify efficacy data have yielded no clear answers, so far. This review offers an in-depth and critical analysis of these trials and intends to evaluate from the cellular biology and clinical cardiology viewpoints, the significant information that has been published since 2002, as well as that emerging from ongoing clinical trials. Emphasis will be placed on cellular types, research designs and methods to evaluate efficacy of each particular treatment modality.

Mesenchymal stem cell therapy for the treatment of amyotrophic lateral sclerosis: signals for hope?

Based on the distinctive cellular, molecular and immunomodulatory traits of mesenchymal stem cells (MSC), it has been postulated that these cells may play a critical role in regenerative medicine. In addition to the participation of MSC in the repair of mesodermal-derived tissues (bone, cartilage), robust data have suggested that MSC may also play a reparative role in conditions involving damage of cells of ectodermal origin. The above content has been supported by the capability of MSC to differentiate into neuron-like cells as well as by a competence to generate a 'neuroprotective' environment. In turn, several preclinical studies have put forward the concept that MSC therapy may represent an option for the treatment of several neurological disorders and injuries, including amyotrophic lateral sclerosis. We expect that the above foundations, which have inspired this review, may result in the founding of an effective and/or palliative therapy for amyotrophic lateral sclerosis.

Mesenchymal stem cells and the treatment of conditions and diseases: the less glittering side of a conspicuous stem cell for basic research.

Not too long ago, several motivated and forward-looking articles were published describing the cellular and molecular properties of mesenchymal stem cells (MSCs), specially highlighting their potential for self-renewal, commitment, differentiation, and maturation into specific mesoderm-derived lineages. A very influential publication of that period entitled "Mesenchymal stem cells: No longer second class marrow citizens" [1] raised the point of view that "…challenges to harness MSC cell therapy to treat diseases … need to wait for the full comprehension that marrow is a rich source of mesenchyme-derived cells whose potential is still far from fully appreciated." Whether or not the prophecy of Gerson was fulfilled, in the last 8 years it has become evident that infusing MSCs into patients suffering a variety of disorders represents a viable option for medical treatment. Accordingly, a vast number of articles have explored the privileged cellular and molecular features of MSCs prepared from sources other than the canonical, represented by the bone marrow. This review will provide more information neither related to the biological attractiveness of MSCs nor to the success after their clinical use. Rather, we would like to underscore several "critical and tangential" issues, not always discussed in biomedical publications, but relevant to the clinical utilization of bone-marrow-derived MSCs.

Therapeutic angiogenesis in patients with severe limb ischemia by transplantation of a combination stem cell product.

OBJECTIVE: Angiogenesis involves the interplay of endothelial progenitor cells, pericytes, growth factors, and cellular matrix components. The use of mesenchymal stem cells, which are closely related to pericytes and produce diverse angiogenic growth factors and matrix molecules, seems to be a promising therapeutic modality. We postulate that the use of a combination cell product (mesenchymal stem cells in conjunction with a source of endothelial progenitor cells) is safe and efficient and may optimize the clinical results obtained with the use of endothelial progenitor cells alone. This study assessed whether the intramuscular infusion of a combination cell product represents a viable, effective, and lasting therapeutic modality to improve perfusion in severely ischemic limbs. METHODS: Patients with limb ischemia (n=26) received an intramuscular (gastrocnemius) infusion of the combination cell product in the most ischemic leg and a placebo product in the (less ischemic) contralateral leg. Clinical follow-up (months 0.5, 1, 2, and 4 postinfusion) included evaluation of pain-free walking time, ankle-brachial index, perfusion scintigraphy, and quality of life survey. RESULTS: No adverse events occurred after infusion. Efficacy assessment indicated that after cell infusion there was a significant improvement in walking time and ankle-brachial index. In addition, technetium-99m-tetrofosmin scintigraphy demonstrated a significant increase of perfusion in the treated limbs compared with the respective control legs. CONCLUSIONS: This phase II clinical trial shows that the use of a combination cell therapy is safe and effective in increasing blood flow in the ischemic legs of patients with limb ischemia.

Myocardial implantation of a combination stem cell product by using a transendocardial MYOSTAR injection catheter: A technical assessment.

AIM: Different types of progenitor cells have been used to improve cardiac conditions after myocardial infarction (MI). Results have shown that while the infusion of a single cell type is safe and feasible, efficacy is modest. Recently, the use of a combination, rather than a single, stem cell product has emerged as an attractive option to improve cardiac outcome after a MI. Before initiating a phase II clinical trial to assess safety and efficacy after the transendocardial infusion of a combination stem cell product, a bench testing assay was designed to validate that delivery through the injection catheter is not associated with cell loss/damage. The latter is important since mesenchymal stem cells (MSC), a component of the cell product, consist of large cells expressing matrix molecules and adhesive receptors. METHODS: The cell product (a mixture of mononuclear cells and MSC) was sequentially injected through a Myostar injection catheter. Exiting fractions were assessed for cell number, viability, capability to restart cell growth and immunophenotype. RESULTS: Cell recovery and viability were high. In turn, exiting cells preserved their biological properties and immunophenotype. CONCLUSIONS: Delivery of cells through a Myostar catheter is safe and not associated with changes in cell survival and/or properties.

Combination stem cell therapy for the treatment of medically refractory coronary ischemia: a Phase I study.

PURPOSE: Infusion of a source of endothelial progenitor cells (EPC) into the ischemic myocardium is emerging as a promising therapy for coronary ischemia, probably mediated by the formation of new blood vessels. Studies have shown that while the procedure is safe and feasible, efficacy results are contentious. The investigators hypothesized that the infusion of a combination cell product consisting of a source of EPC and mesenchymal stem cells (MSC) is safe and promotes the formation of more stable and mature blood vessels resulting in improved clinical outcomes. METHODS: Ten patients with stable angina pectoris (class III to IV) on maximal medical therapy were included. All patients had ≥ 70% stenosis in at least one coronary artery, and none was considered a candidate for percutaneous coronary intervention or coronary artery bypass graft. End points were feasibility and safety of intracoronary infusion of the combination cell product and assessment of myocardial ischemia, left ventricular ejection fraction (LVEF), and quality of life at 6 months postinfusion. RESULTS: Six months after cell infusion there were no adverse clinical events. Functional cardiac evaluation during the same period showed significant improvements in LVEF (average increase: 11%, P = .02) and myocardial ischemia (average decrease: 1.8 fold, P = .02). Additionally, all patients described significant improvements in quality of life. CONCLUSIONS: Despite the inherent limitations associated with a Phase I clinical trial, this study demonstrates that the intracoronary infusion of the combination cell product is feasible and safe and also insinuates that this form of therapy may be beneficial.

Combination stem cell therapy for the treatment of severe limb ischemia: safety and efficacy analysis.

The infusion of a source of endothelial progenitors (EPCs) to limb ischemia (LB) patients has been used to increase angiogenesis. Because the formation of new blood vessels involves, in addition to EPCs, other cells and angiogenic regulators, we postulate that a combination cell therapy including EPCs and mesenchymal stem cells (a source of pericytes progenitors and angiogenic regulators) may represent a preferential stimuli for the development of blood vessels. In this phase I clinical trial, patients with LI were infused with a cell product consisting of autologous bone marrow-derived mononuclear and mesenchymal stem cells. After 10 2 months of follow-up, efficacy assessment demonstrated improvements in walking time, ankle brachial pressure, and quality of life. Concomitantly, angiographic and 99mTc-TF perfusion scintigraphy scores confirmed increased perfusion in the treated limbs. These results show that the use of a combination cell therapy is safe, feasible, and appears effective in patients with LI.

Intracoronary infusion of a combination of bone marrow-derived stem cells in dogs.

BACKGROUND: Infusion of diverse types of bone marrow cells, as a source of endothelial progenitor cells (EPCs), into the ischemic myocardium is emerging as a promising therapy for coronary ischemia, probably mediated by the formation of new blood vessels. Studies have shown that while the procedure is safe and feasible, efficacy results are contentious. The investigators in the present preclinical translation study hypothesized that the infusion of a combination cell product consisting of EPCs and other cell types, such as mesenchymal stem cells, promotes the formation of more stable and mature blood vessels resulting in improved clinical outcomes. The safety and feasibility of the intracoronary infusion of such a cell combination was assessed in a canine model. METHODS: A mixture of canine autologous mononuclear cells (as the source of EPCs) and ex vivo-expanded bone marrow-derived mesenchymal stem cells or a placebo solution were intracoronarily infused into healthy dogs. Follow-up after cell/placebo infusion included an electrocardiogram, serum cardiac enzyme testing, a transthoracic echocardiography and a histopathological heart examination. RESULTS: On follow-up at all time points after infusion, no significant changes or abnormalities in vital signs, electrocardiogram, transthoracic echocardiography and heart histology were detected. CONCLUSIONS: From a clinical perspective, the safety and feasibility of the protocol used in the present animal study demonstrated clinical relevance and provided direct evidence supporting the intracoronary infusion of combination stem/progenitor cell products.