This study tested whether circulatory endothelial progenitor cells (EPCs) derived from peripheral arterial occlusive disease (PAOD) patients after receiving combined autologous CD34+ cell and hyperbaric oxygen (HBO) therapy (defined as rejuvenated EPCs) would salvage nude mouse limbs against critical limb ischemia (CLI). Adult-male nude mice (n = 40) were equally categorized into group 1 (sham-operated control), group 2 (CLI), group 3 (CLI-EPCs (6 × 10⁵) derived from PAOD patient’s circulatory blood prior to CD34⁺ cell and HBO treatment (EPC^Pr-T) by intramuscular injection at 3 h after CLI induction) and group 4 (CLI-EPCs (6 × 10⁵) derived from PAOD patient’s circulatory blood after CD34⁺ cell and HBO treatment (EPC^Af-T) by the identical injection method). By 2, 7 and 14 days after the CLI procedure, the ischemic to normal blood flow (INBF) ratio was highest in group 1, lowest in group 2 and significantly lower in group 4 than in group 3 (p < 0.0001). The protein levels of endothelial functional integrity (CD31/von Willebrand factor (vWF)/endothelial nitric-oxide synthase (eNOS)) expressed a similar pattern to that of INBF. In contrast, apoptotic/mitochondrial-damaged (mitochondrial-Bax/caspase-3/PARP/cytosolic-cytochrome-C) biomarkers and fibrosis (Smad3/TGF-ß) exhibited an opposite pattern, whereas the protein expressions of anti-fibrosis (Smad1/5 and BMP-2) and mitochondrial integrity (mitochondrial-cytochrome-C) showed an identical pattern of INBF (all p < 0.0001). The protein expressions of angiogenesis biomarkers (VEGF/SDF-1α/HIF-1α) were progressively increased from groups 1 to 3 (all p < 0.0010). The number of small vessels and endothelial cell surface markers (CD31⁺/vWF⁺) in the CLI area displayed an identical pattern of INBF (all p < 0.0001). CLI automatic amputation was higher in group 2 than in other groups (all p < 0.001). In conclusion, EPCs from HBO-C34+ cell therapy significantly restored the blood flow and salvaged the CLI in nude mice.

This review paper delves into the current body of evidence, offering a thorough analysis of the impact of large-conductance Ca²⁺-activated K⁺ (BK_Ca or BK) channels on the electrical dynamics of the heart. Alterations in the activity of BK_Ca channels, responsible for the generation of the overall magnitude of Ca²⁺-activated K⁺ current at the whole-cell level, occur through allosteric mechanisms. The collaborative interplay between membrane depolarization and heightened intracellular Ca²⁺ ion concentrations collectively contribute to the activation of BK_Ca channels. Although fully developed mammalian cardiac cells do not exhibit functional expression of these ion channels, evidence suggests their presence in cardiac fibroblasts that surround and potentially establish close connections with neighboring cardiac cells. When cardiac cells form close associations with fibroblasts, the high single-ion conductance of these channels, approximately ranging from 150 to 250 pS, can result in the random depolarization of the adjacent cardiac cell membranes. While cardiac fibroblasts are typically electrically non-excitable, their prevalence within heart tissue increases, particularly in the context of aging myocardial infarction or atrial fibrillation. This augmented presence of BK_Ca channels’ conductance holds the potential to amplify the excitability of cardiac cell membranes through effective electrical coupling between fibroblasts and cardiomyocytes. In this scenario, this heightened excitability may contribute to the onset of cardiac arrhythmias. Moreover, it is worth noting that the substances influencing the activity of these BK_Ca channels might influence cardiac electrical activity as well. Taken together, the BK_Ca channel activity residing in cardiac fibroblasts may contribute to cardiac electrical function occurring in vivo.

Background: We investigated whether shock wave (SW)-pretreated autologous adipocyte-derived mesenchymal stem cells (ADMSCs) seeded in the cell-sheet scaffold (CSS) could inhibit left ventricular (LV) remodeling and improve LV ejection fraction (LVEF) in old myocardial infarction (MI). Methods: Mini-pigs (n=20) were divided into group 1 (sham-operated control), group 2 (old MI), group 3 (old MI + autologous ADMSCs/1.0×10⁷ in CSS on LV myocardium), and group 4 [old MI + SW (0.12 mJ/mm² for total 140 shots)-pretreated ADMSCs in CSS on LV myocardium]. Treatments started on day 28 after MI induction. In-vivo and in-vitro studies were conducted. Results: Cell viability/relative mitochondria DNA expression/mitochondrial cytochrome C/adenosine triphosphate concentration in ADMCSs and protein expressions of angiogenesis factors [vascular endothelial growth factor (VEGF)/stromal cell-derived factor-1 (SDF-1)/mitochondrial respiratory chain complexes I–IV/oxygen consumption rate] were higher in group 4 than in group 3 (P<0.001). By day 180, LVEF and small vessel numbers in the peri-infarct or infarct area were highest in group 1, lowest in group 2, and significantly lower in group 3 than in group 4. In contrast, the LV dimension was opposite to the pattern of change in LVEF in all groups (P<0.0001). The basal/middle/apical infarct and fibrotic areas were inversely related to LVEF in all groups (all P<0.0001). Protein levels of angiogenetic markers (SDF-1α/C-X-C chemokine receptor type 4/VEGF/angiopoietin-1) were significantly and persistently increased from groups 1 to 4. In contrast, protein levels of endothelial cell markers (von Willebrand factor or endothelial nitric oxide synthase) showed an identical pattern to LVEF in all groups (all P<0.0001). Conclusion: SW pretreatment of ADMSCs seeded in CSS offered significant benefits in preserving LV performance and ameliorating LV remodeling in mini-pigs with old MI.