Potential beneficial effects of ixmyelocel-T in the treatment of atherosclerotic diseases

Safety and efficacy of bone marrow-derived cells therapy on cardiomyopathy: a meta-analysis

BACKGROUND

Controversial results still existed on the clinical utility of bone marrow-derived cells (BMCs) for cardiomyopathy (CMP). This study aims to reveal the true power of this promising approach by synthesizing all the available data on this subject matter.

METHODS

Twenty studies including 1418 patients were identified from systematic search. Weighted mean differences for changes in left ventricular ejection fraction (LVEF), left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), 6-min walk distance, and NYHA functional class were estimated with a random-effects model. Major adverse cardiovascular event (MACE), rehospitalization, all-cause mortality, and patients' quality of life were also calculated.

RESULTS

Compared with the control group, BMC therapy resulted in greater LVEF (3.72%, 95% CI 2.31 to 5.13, P < 0.0001), 6-min walk distance (53.16, 95% CI 25.17 to 81.10, P = 0.0002), NYHA functional class (- 0.48, 95% CI - 0.65 to - 0.31, P < 0.0001), and smaller LVESV (- 16.79, 95% CI - 27.21 to - 6.38, P = 0.002). BMC treatment significantly reduced the mortality rate and improved patients' quality of life. No significant difference was found between the BMCs and control group in LVEDV, MACE, and rehospitalization rate. However, the outcomes showed a clear trend in favor of the BMC group. Subgroup analysis showed that LVEF improved greater in a subgroup of intracoronary infusion, BMSC, or higher cell dose.

CONCLUSION

The results of the current meta-analysis suggest that BMC treatment for CMP is safe and feasible. This therapy was associated with persistent improvements in LV function, LV remodeling, functional class, patients' survival, and quality of life. Intracoronary infusion of high-dose (> 10⁸) BMSC might be a better therapeutic option for CMP patients. Further evidences are needed to verify our results.

Adjuvant role of macrophages in stem cell-induced cardiac repair in rats

Bone marrow-derived mesenchymal stem cells (BMMSCs) are used extensively for cardiac repair and interact with immune cells in the damaged heart. Macrophages are known to be modulated by stem cells, and we hypothesized that priming macrophages with BMMSCs would enhance their therapeutic efficacy. Rat bone marrow-derived macrophages (BMDMs) were stimulated by lipopolysaccharide (LPS) with or without coculture with rat BMCs. In the LPS-stimulated BMDMs, induction of the inflammatory marker iNOS was attenuated, and the anti-inflammatory marker Arg1 was markedly upregulated by coculture with BMMSCs. Myocardial infarction (MI) was induced in rats. One group was injected with BMMSCs, and a second group was injected with MIX (a mixture of BMMSCs and BMDMs after coculture). The reduction in cardiac fibrosis was greater in the MIX group than in the BMC group. Cardiac function was improved in the BMMSC group and was substantially improved in the MIX group. Angiogenesis was better in the MIX group, and anti-inflammatory macrophages were more abundant in the MIX group than in the BMMSC group. In the BMMSCs, interferon regulatory factor 5 (IRF5) was exclusively induced by coculture with macrophages. IRF5 knockdown in BMMSCs failed to suppress inflammatory marker induction in the macrophages. In this study, we demonstrated the successful application of BMDMs primed with BMMSCs as an adjuvant to cell therapy for cardiac repair.

Therapeutic angiogenesis for critical limb ischemia

The application of gene- and cell-based therapies to promote angiogenesis is a novel concept to treat lower-limb critical limb ischemia (CLI) and may provide an unmet need for patients with no options for revascularization. Proof of concept was demonstrated in animal models resulting in clinical trials that have confirmed the feasibility and short-term efficacy of intramuscular injection of angiogenetic tissue growth factors or bone marrow stem cells. The safety of these biologic therapies has been demonstrated in randomized clinical trials with no "off-target" angiogenesis, growth of occult tumors, or progression of diabetic retinopathy. Current phase III randomized clinical trials using a DNA plasmid with the hepatocyte growth factor gene or bone marrow aspirate concentrate of mesenchymal cells are designed to address several crucial issues, including proper patient selection criteria, relevant clinical endpoints, and long-term efficacy. Because effectiveness of these novel therapies remains to be established, ongoing and future randomized clinical trials should be placebo-controlled, investigator-blinded, and have amputation-free survival as the primary endpoint. Further development of efficient gene transfer techniques and keeping transplanted stem cells healthy have the potential to make biologic therapies more robust in promoting angiogenesis, tissue regeneration, and resolution of CLI symptoms. If sustained efficacy can be demonstrated, new therapeutic strategies for patients with CLI will be available for clinicians, ie, limb revascularization using angiogenic gene or stem cell therapy alone, or in conjunction with endovascular intervention.