Background— Multilineage developmental capacity of the CD34 + cells, especially into cardiomyocytes and smooth muscle cells (SMCs), is still controversial. In the present study we performed a series of experiments to prove our hypothesis that vasculogenesis and cardiomyogenesis after myocardial infarction (MI) may be dose-dependently enhanced after CD34 + cell transplantation. Methods and Results— Peripheral blood CD34 + cells were isolated from total mononuclear cells of patients with limb ischemia by apheresis after 5-day administration of granulocyte colony-stimulating factor. PBS and 1×10 3 (low), 1×10 5 (mid), or 5×10 5 (high) CD34 + cells were intramyocardially transplanted after ligation of the left anterior descending coronary artery of nude rats. Functional assessments with the use of echocardiography and a microtip conductance catheter at day 28 revealed dose-dependent preservation of left ventricular function by CD34 + cell transplantation. Necropsy examination disclosed dose-dependent augmentation of capillary density and dose-dependent inhibition of left ventricular fibrosis. Immunohistochemistry for human-specific brain natriuretic peptide demonstrated that human cardiomyocytes were dose-dependently observed in ischemic myocardium at day 28 (high, 2480±149; mid, 1860±141; low, 423±9; PBS, 0±0/mm 2 ; P <0.05 for high versus mid and mid versus low). Immunostaining for smooth muscle actin and human leukocyte antigen or Ulex europaeus lectin type 1 also revealed dose-dependent vasculogenesis by endothelial cell and SMC development after CD34 + cell transplantation. Reverse transcriptase–polymerase chain reaction indicated that human-specific gene expression of cardiomyocyte (brain natriuretic peptide, cardiac troponin-I, myosin heavy chain, and Nkx 2.5), SMC (smooth muscle actin and sm22α), and endothelial cell (CD31 and KDR) markers were dose-dependently augmented in MI tissue. Conclusions— Human CD34 + cell transplantation may have significant and dose-dependent potential for vasculogenesis and cardiomyogenesis with functional recovery from MI.
A number of preclinical studies have indicated the therapeutic potential of endothelial progenitor cells for vascular regeneration in ischemic diseases. A phase I/IIa clinical trial of transplantation of autologous CD34+ cells, the endothelial and hematopoietic progenitor‐enriched fraction, was performed in no‐option patients with atherosclerotic peripheral artery disease or Buerger's disease with critical limb ischemia (CLI). CD34+ cells were isolated from the G‐CSF‐mobilized apheresis product using a magnetic cell sorting system. CD34+ cells (105/kg, n = 6; 5 × 105/kg, n = 8; or 106/kg, n = 3) were injected i.m. into the leg with more severe ischemia. The Efficacy Score, representing changes in the toe brachial pressure index (TBPI), Wong‐Baker FACES pain rating scale, and total walking distance 12 weeks after cell transplantation, the primary endpoint, was positive, indicating improvement in limb ischemia in all patients, although no significant dose‐response relationship was observed. During the 12‐week observation after cell therapy, the Wong‐Baker FACES pain rating scale, TBPI, transcutaneous partial oxygen pressure, total or pain‐free walking distance, and ulcer size serially improved in all patients. No death or major amputation occurred, and severe adverse events were rare, although mild to moderate events relating to G‐CSF and leukapheresis were frequent during the 12‐week follow‐up. In conclusion, the outcomes of this prospective clinical study indicate the safety and feasibility of CD34+ cell therapy in patients with CLI. Favorable trends in efficacy parameters encourage a randomized and controlled trial in the future. STEM CELLS 2009;27:2857–2864
Retinal Müller glia can serve as a source for regeneration of damaged retinal neurons in fish, birds and mammals. However, the proliferation rate of Müller glia has been reported to be low in the mammalian retina. To overcome this problem, growth factors and morphogens have been studied as potent promoters of Müller glial proliferation, but the molecular mechanisms that limit the proliferation of Müller glia in the mammalian retina remain unknown. In the present study, we found that the degree of damage-induced Müller glia proliferation varies across mouse strains. In mouse line 129×1/SvJ (129), there was a significantly larger proliferative response compared with that observed in C57BL/6 (B6) after photoreceptor cell death. Treatment with a Glycogen synthase kinase 3 (GSK3) inhibitor enhanced the proliferation of Müller glia in 129 but not in B6 mouse retinas. We therefore focused on the different gene expression patterns during retinal degeneration between B6 and 129. Expression levels of Cyclin D1 and Nestin correlated with the degree of Müller glial proliferation. A comparison of genome-wide gene expression between B6 and 129 showed that distinct sets of genes were upregulated in the retinas after damage, including immune response genes and chromatin remodeling factors.
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