Search Results (83)

Myeloid-derived growth factor (MYDGF) is a monocyte- and macrophage-secreted protein with anti-apoptotic and pro-angiogenic properties that has demonstrated protective effects in models of myocardial ischemia, but its role in peripheral ischemic injury has not been evaluated. We investigated the effects of recombinant human MYDGF (hMYDGF) in a murine hindlimb ischemia model. Male C57BL/6 mice underwent femoral artery ligation and were treated with continuous subcutaneous infusion of recombinant hMYDGF, vehicle control, or vascular endothelial growth factor (VEGF) as a positive control. Limb perfusion was assessed longitudinally using laser speckle contrast imaging, and functional recovery was evaluated using standardized limb function scoring. Recombinant hMYDGF significantly improved blood flow recovery in the ischemic limb compared with vehicle at all post-surgical time points, achieving levels of perfusion comparable to VEGF. Improved perfusion translated into accelerated early functional recovery, with a greater proportion of recombinant hMYDGF-treated mice retaining normal toe flexion. Immunohistochemical analyses revealed significantly increased CD34⁺ endothelial cell staining in both quadriceps and gastrocnemius muscles in recombinant hMYDGF-treated mice, consistent with enhanced angiogenesis, while alpha-smooth muscle actin staining did not differ between groups. Collectively, these findings demonstrate that recombinant hMYDGF restores blood flow and accelerates functional recovery following ischemic injury, supporting its therapeutic potential for ischemic diseases. Full article

Cellular therapies harnessing the potential of endothelial colony-forming cells (ECFCs) for therapeutic revascularization in patients with critical limb ischemia (CLI) have garnered much interest. However, limited cell persistence following intramuscular injection into ischemic tissues has prompted the development of biomaterials as cell-delivery platforms to support cell survival and enhance therapeutic outcomes. This study explored the use of hydrogels derived from human decellularized adipose tissue (DAT) as a cell-instructive platform for ECFC delivery. In vitro studies confirmed high initial ECFC viability at 1 day following encapsulation in the DAT hydrogels but revealed that cell viability and proliferation were reduced over time in culture as compared to ECFCs cultured on tissue culture polystyrene (TCP). However, the ECFCs cultured within the DAT hydrogels showed similar ECFC cell surface marker expression patterns compared to ECFCs cultured on TCP after 6 days in culture, supporting that their phenotype was maintained. Subsequent testing focused on comparing a low (2.4 × 10⁵ cells) and high (1 × 10⁶ cells) dose of ECFCs delivered in either saline or within DAT hydrogels in a femoral artery ligation-induced CLI (FAL-CLI) model in NOD/SCID mice over 35 days. Bioluminescence imaging results showed that the low dose of ECFCs delivered in DAT hydrogels demonstrated enhanced retention on days 14, 21, and 28 compared to delivery in saline. Despite this finding, there were no observed improvements in hindlimb perfusion between delivery strategies, which may be related to the robust collateral vessel formation observed in this model with a µCT-based angiography method. Overall, this work supports that DAT hydrogels can enhance localized ECFC retention following intramuscular injection in mice with femoral artery ligation but emphasizes that enhanced retention may be insufficient for improving functional vascular regeneration. Full article

Arteriogenesis, the growth of pre-existing collateral arteries in response to arterial occlusion, is critically regulated by perivascular immune cells. While innate immune contributions are well-established, the role of B lymphocytes remains poorly understood. We investigated the impact of B cell deficiency on arteriogenesis using B cell-deficient J_HT mice in a murine hindlimb model of femoral artery ligation (FAL). Laser-Doppler perfusion imaging, immunofluorescence staining, Giemsa staining, flow cytometry, and differential blood counts were performed at defined time points after FAL. B cell-deficient mice exhibited significantly impaired perfusion recovery on days 3 and 7 post-FAL, accompanied by reduced collateral artery diameter growth and diminished vascular cell proliferation. Early immune analysis revealed elevated platelet–neutrophil aggregate (PNA) formation and increased perivascular mast cell degranulation in B cell-deficient mice despite unchanged circulating cell counts. On day 7, perivascular M2-like macrophage numbers were selectively reduced. Furthermore, B cell deficiency disrupted the temporal reprogramming of γδ T cell subsets, impairing the shift from pro-inflammatory IFN-γ-associated to anti-inflammatory IL-10-associated subpopulations. These findings demonstrate for the first time that B cells are essential coordinators of the sequential innate and regenerative immune response driving productive collateral artery growth, positioning them as potential targets for therapeutic arteriogenesis strategies. Full article

Reparative macrophage polarization and macrophage-derived reactive oxygen species (ROS) are required for ischemia-induced revascularization in peripheral artery disease (PAD). Our previous study showed that mitochondrial fission protein dynamin-related protein 1 (DRP1) promotes reparative polarization and metabolic reprogramming in macrophages and post-ischemic neovascularization. However, the redox-dependent mechanism governing DRP1 activation in this context remains elusive. Here, using a mouse hindlimb ischemia (HLI) model of PAD, we identify cysteine sulfenylation (CysOH) of DRP1 as a critical redox modification induced in ischemic bone marrow (BM)-derived cells. BM chimeric mice reconstituted with CRISPR/Cas9-generated “redox-dead” DRP1-C631A knock-in mutant (Drp1^C/A) BM exhibited markedly reduced limb perfusion recovery and CD31⁺ capillary density in ischemic muscles following HLI. These defects were associated with enhanced Ly6G⁺ neutrophil accumulation, pro-inflammatory F4/80⁺CD80⁺ M1-like macrophages and reduced anti-inflammatory F4/80⁺CD206⁺ M2-like macrophages in ischemic muscle. Mechanistically, using an in vitro PAD model, hypoxia serum starvation (HSS) rapidly induced NADPH oxidase 2-dependent cytosolic ROS production and DRP1-CysOH formation in wild-type macrophages. In contrast, Drp1^C/A macrophages failed to undergo DRP1-CysOH-dependent mitochondrial fission under HSS, resulting in aberrant metabolic reprogramming characterized by enhanced glycolysis and mitochondrial ROS, pro-inflammatory p-NF-κB and M1-genes, and suppressed anti-inflammatory p-AMPK, efferocytosis and M2-genes. Thus, our findings establish DRP1 sulfenylation as a previously unrecognized redox-sensing mechanism that links ischemia-induced ROS to reparative macrophage reprogramming and revascularization, identifying a novel therapeutic target for PAD. Full article

Peripheral nerve ischemia–reperfusion injury is considered to contribute to sensory disturbances that impair quality of life in patients with diabetic neuropathy and chemotherapy-induced neuropathy. However, the spinal mechanisms underlying these disturbances remain unclear, partly due to the lack of established animal models and evaluation systems. In the present study, we used a rat hindlimb ischemia–reperfusion model and in vivo extracellular recording to examine bidirectional changes in neuronal activity in the spinal dorsal horn. Ischemia was induced by tightly binding the rat ankle with a rubber band, followed by reperfusion. Behavioral analysis showed a significant increase in hindlimb licking behavior after reperfusion, indicating the development of sensory disturbance-like responses. Extracellular recordings from superficial dorsal horn neurons showed diverse patterns of spontaneous firing and responses to mechanical stimulation, with both hypersensitive and desensitized responses. Furthermore, mRNA expression levels of immediate early genes (Egr1, Egr3, and Fos) were upregulated in the spinal cord after reperfusion. These results suggest that this ischemia–reperfusion model reproduces complex neuronal responses relevant to peripheral neuropathy and provides a useful evaluation system for evaluating both increased and decreased neural activity. This approach may contribute to elucidating the mechanisms of sensory disturbances and to the development of new treatments for neuropathic conditions. Full article

Sildenafil, a selective phosphodiesterase-5 (PDE5) inhibitor, supports vascular remodeling, but its effects on angiogenesis and regeneration of ischemic muscle tissue are not fully understood. We investigated the function of sildenafil by employing a murine hindlimb model of ischemia, in which ischemia and angiogenesis is induced by femoral artery ligation (FAL) in the lower leg of mice. Then, 7 days after FAL or sham operation, gastrocnemius muscles of sildenafil-treated and control mice were isolated and processed for histological and immunofluorescence analyses. Sildenafil treatment led to reduced apoptotic areas within the ischemic tissue (ascertained via TUNEL assay) and increased angiogenesis, evidenced by a higher capillary-to-muscle fiber ratio and an augmented number of proliferating capillary cells (CD31⁺/CD45⁻/BrdU⁺), compared to controls. We observed a decrease in the total count of leukocytes (CD45⁺) in sildenafil-treated mice. Regarding macrophage infiltration, we found a reduced total number of macrophages (CD68⁺), along with a shift in macrophage polarization toward the pro-angiogenic and anti-inflammatory M2-like phenotype (CD68⁺/MRC1⁺). In summary, we show that sildenafil treatment contributes to angiogenesis and the regeneration of ischemic muscle tissue, most likely by attenuating inflammatory responses and influencing macrophage polarization in direction to regenerative M2-like polarized macrophages. Full article

Background/Objectives: In severe peripheral artery disease (PAD) with limb ischemia, hypercholesterolemia (HC) is associated with impaired neovascularization. Extracellular vesicles (EVs) are present within ischemic muscles, and they contain microRNAs (miRs) involved in several biological functions, including angiogenesis and neovascularization. Methods: We used a mouse model of PAD and compared the response to hindlimb ischemia in hypercholesterolemic ApoE^−/− vs. normocholesterolemic mice. Next-generation sequencing (NGS) was used to perform full miR expression profiling in ischemic skeletal muscles and in EVs of varying sizes—large EVs (lEVs) and small EVs (sEVs)—within these muscles. Results: We identified several miRs with potential pro-angiogenic effects (angiomiRs) that are reduced by HC in lEVs (Let-7b-5p, miR-151-3p, Let-7c-5p) or sEVs (miR-21a-5p, miR-196b-5p, miR-340-5p). As proof of principle, we showed that the overexpression of Let-7b-5p in lEVs, or miR-21a-5p in sEVs, can significantly increase the angiogenic capacity of these EVs in vitro. HC also impaired the enrichment of specific angiomiRs in lEVs (miR-100-5p), sEVs (miR-142a-3p), or in both lEVs and sEVs (miR-146b-5p). In silico approaches, including the prediction of miR targets, pathway unions, and gene unions, identified the resulting predictive effects of HC-modulated miRs in EVs on processes with key roles in the modulation of angiogenesis and neovascularization, such as the regulation of the actin cytoskeleton and focal adhesion and the HIF-1, MAPK, AMPK, and PI3K-Akt signaling pathways. Conclusions: Our results constitute an important first step towards the identification of specific miRs that could be targeted to improve EV angiogenic function in hypercholesterolemic conditions and reduce tissue ischemia in patients with severe PAD. Full article

Peripheral artery disease (PAD) remains a great threat to the health of older people globally. Nitric oxide (NO), as an important signaling molecule, is integral to processes such as angiogenesis, inflammation, and tissue regeneration, making it a potential candidate for PAD treatment. Nevertheless, NO—based therapies are frequently limited in clinical utility, primarily due to the lack of effective strategies for fine-tuning the release of exogenous NO. In this study, we developed an enzyme—prodrug pair based on endocellulase (Cel5A-h38), which ensured complete bioorthogonality, thus avoiding interference with endogenous enzymes and eliciting an inflammatory response. This delivery system enables localized and controlled NO release, thus preventing side effects induced by systemic exposure. The therapeutic efficacy of the NO delivery system was systematically evaluated in a porcine model of hindlimb ischemia. Our results confirmed the benefits of targeted NO delivery in hindlimb ischemia, which include enhanced neovascularization and tissue perfusion, reduced inflammation, and alleviated muscle fibrosis, demonstrating its optimal translational potential. Full article

Vascular smooth muscle cells (VSMCs) can dynamically change their phenotype between contractile and synthetic forms in response to environmental stress, which is pivotal in maintaining vascular homeostasis and mediating pathological remodeling of blood vessels. We previously reported that suppression of canonical transient receptor potential 6 (TRPC6) channel-mediated cation entry sustains VSMCs contractile phenotype and promotes the blood flow recovery after hindlimb ischemia in mice. We also reported that Zn²⁺, a metal biomolecule mobilized by TRPC6 channel activation, exerts potential beneficial effects on cardiac contractility and remodeling. Therefore, we hypothesized that TRPC6-mediated Zn²⁺ influx participates in phenotype switching of VSMCs and vascular remodeling. We established rat aortic smooth muscle cells (RAoSMCs) stably expressing wild type (WT) and Zn²⁺ only impermeable TRPC6 (KYD) mutant. Although the resting phenotypes were similar in both RAoSMCs, pharmacological TRPC6 activation by PPZ2 prevented the transforming growth factor (TGF) β-induced reduction in the intracellular Zn²⁺ amount and contractile differentiation in RAoSMCs (WT), but failed to prevent them in RAoSMCs (KYD). There were no significant differences in TRPC6-dependent cation currents among all RAoSMCs pretreated with or without TGFβ and/or PPZ2, suggesting that TRPC6 channels are functionally expressed in RAoSMCs regardless of their phenotype. Treatment of mice with PPZ2 attenuated the progression of vascular remodeling caused by chronic angiotensin II infusion. These results suggest that Zn²⁺ influx through TRPC6 channels negatively regulates the TGFβ-induced contractile differentiation of VSMCs and the progression of vascular remodeling in rodents. Full article

Brain-derived neurotropic factor (BDNF) is expressed by skeletal muscle as a myokine. Our previous work showed that the active precursor, proBDNF, is the predominant form of BDNF expressed in skeletal muscle, and that following skeletal muscle injury, proBDNF levels are significantly increased. However, the function of the muscle-derived proBDNF in injury-induced inflammation has yet to be fully understood. Using a model of tourniquet-induced ischemia–reperfusion (IR) injury of the hindlimb, this study presents, for the first time, strong and novel evidence that following IR injury, proBDNF is released from skeletal muscle into circulation as an endocrine signaling molecule. Further, this study shows that 1 day post-IR injury, the proBDNF receptor, p75^NTR, is upregulated 12-fold in splenic monocytes, which are known to be quickly mobilized to the injury site. We demonstrate that p75^NTR plays a role in the activation of splenic monocytes, and that treatment with a p75^NTR small-molecule modulator, LM11A-31, significantly reduced monocyte inflammatory responses upon lipopolysaccharide stimulation. Overall, the present study establishes proBDNF as a myokine that plays a significant role in skeletal muscle injury-induced inflammation through its receptor, p75^NTR, which may be modulated using LM11A-31 as potential translational therapeutic against injury and inflammation. Full article

Background/Objectives: Chronic Limb-Threatening Ischemia (CLTI) is a chronic limb ischemic disease caused by vascular lesions, characterized by pain, ulcers, and gangrene, which can be life-threatening in severe cases. The objective of this study is to explore whether Berbamine (BBM) can protect against and repair ischemic muscle tissue in the lower limbs; Methods: Using a mouse hindlimb ischemia (HLI) model, 36 C57BL6 mice were divided into sham, HLI, and HLI+BBM treatment groups. Results: Our findings indicate that BBM can restore motor function and muscle tissue pathology in mice, potentially by inhibiting the nuclear translocation of nuclear factor kappa-B (NF-κB), thereby alleviating tissue inflammation caused by chronic ischemia, reducing muscle cell apoptosis, inhibiting M1 macrophage polarization, and promoting angiogenesis. Conclusions: Our research suggests that BBM has the potential to protect against ischemic damage in lower limb muscle tissue, providing a new approach to the treatment of CLTI. Full article

Objective: Monocytes are innate immune cells that play a central role in inflammation, an essential component during neovascularization. Our recent publication demonstrated that ischemia training by 24 h unilateral occlusion of the femoral artery (FA) can modify bone marrow-derived monocytes (BM-Mono), allowing them to improve collateral remodeling in a mouse model of hindlimb ischemia. Here, we expand on our previous findings, investigating a potential systemic effect of ischemia training and how this training can impact BM-Mono. Methods and Results: BM-Mono from mice exposed to ischemia training (24 h) or Sham (same surgical procedure without femoral artery occlusion–ischemia training) procedures were used as donors in adoptive transfer experiments where recipients were subjected to hindlimb ischemia. Donor cells were divided corresponding to the limb from which they were isolated (left—limb previously subjected to 24 h ischemia and right—contralateral limb). Recipients who received 24 h ischemic-trained monocytes isolated from either limb had remarkable blood flow recovery compared to recipients with Sham monocytes (monocytes isolated from Sham group—no ischemia training). Since these data suggested a systemic effect of ischemic training, circulating extracellular vesicles (EVs) were investigated as potential players. EVs were isolated from both groups, 24 h-trained and Sham, and the former showed increased expression of histone deacetylase 1 (HDAC1), which is known to downregulate 24-dehydrocholesterol reductase (Dhcr24) gene expression. Since we previously revealed that ischemia training downregulates Dhcr24 in BM-Mono, we incubated EVs from 24 h-trained and Sham groups with wild-type (WT) BM-Mono and demonstrated that WT BM-Mono incubated with 24 h-trained EVs had lower gene expression of Dhcr24 and an HDAC1 inhibitor blunted this effect. Next, we repeated the adoptive transfer experiment using Dhcr24 KO mice as donors of BM-Mono for WT mice subjected to hindlimb ischemia. Recipients who received Dhcr24 KO BM-Mono had greater limb perfusion than those who received WT BM-Mono. Further, we focused on the 24 h-trained monocytes (which previously showed downregulation of Dhcr24 gene expression and higher desmosterol) to test the expression of a few genes downstream of the desmosterol pathway, confirm the Dhcr24 protein level and assess its differentiation in M2-like macrophage phenotype. We found that 24 h-trained BM-Mono had greater expression of key genes in the desmosterol pathway, such as liver X receptors (LXRs) and ATP-binding cassette transporter (ABCA1), and we confirmed low protein expression of Dhcr24. Further, we demonstrated that ischemic-trained BM-Mono polarized towards an anti-inflammatory M2 macrophage phenotype. Finally, we demonstrated that 24 h-trained monocytes adhere less to endothelial cells, and the same pattern was shown by WT BM-Mono treated with Dhcr24 inhibitor. Conclusions: Ischemia training leads to a systemic effect that, at least in part, involves circulating EVs and potential epigenetic modification in BM-Mono. These ischemic-trained BM-Mono demonstrated an anti-inflammatory phenotype towards M2 macrophage differentiation and less ability to adhere to endothelial cells, which is associated with the downregulation of Dhcr24 in those cells. These data together suggest that Dhcr24 might be an important target within monocytes to improve the outcomes of hindlimb ischemia. Full article

Acute limb ischemia (ALI) is a sudden lack of blood flow to a limb, primarily caused by arterial embolism and thrombosis. Various experimental animal models, including non-invasive and invasive methods, have been developed and successfully used to induce limb ischemia-reperfusion injuries (L-IRI). However, there is no consensus on the methodologies used in animal models for L-IRI, particularly regarding the assessment of functional recovery. The present study aims to compare different approaches that induce L-IRI and determine the optimal animal model to study functional limb recovery. In this study, we applied a pneumatic cuff as a non-invasive method and ligated the aorta, iliac, or femoral artery as invasive methods to induce L-IRI. We have measured grip strength, motor function, creatine kinase level, inflammatory markers such as nuclear factor NF-κB, interleukin-6 (IL-6), hypoxia markers such as hypoxia-induced factor-1$\mathsf{\alpha }$ (HIF-1$\mathsf{\alpha }$), and evaluated the muscle injury with hematoxylin and eosin (H&E) staining in Sprague Dawley rats after inducing L-IRI. The pneumatic pressure cuff method significantly decreased the muscle strength of the rats, causing the loss of ability to hold the grid and inducing significant limb function impairment, while artery ligations did not. We conclude from this study that the tourniquet cuff method could be ideal for studying functional recovery after L-IRI in the rat model. Full article

In this study, the effects of different combinations of the genes Vegf, Ang, and Gdnf injected both using direct virus-mediated injection (adenovirus, Ad5) and umbilical cord blood mononuclear cells (UCBCs) on the processes of stimulation of post-ischemic innervation, angiogenesis, and regeneration in skeletal muscle were investigated in a rat hindlimb chronic ischemia model. It was shown that more pronounced stimulation of angiogenesis and restoration of post-ischemic innervation were achieved both in the early (28 days post-ischemia, dpi) and late (42 dpi) terms of the experiment in the calf muscle when UCBCs delivered the combination of Ad5-Vegf and Ad5-Ang compared to the direct injection of the same vector combination into the area of ischemia. At the same time, the inclusion of Ad5-Gdnf in the combination of Ad5-Vegf and Ad5-Ang directly injected or administered by UCBCs provided a significant increase in the number of centronuclear muscle fibers, indicating stimulation of post-ischemic reparative myogenesis. This study allowed us to determine the most effective gene combinations for angiogenesis and neurogenesis, which, in the future, may serve as the basis for the development of gene and gene cell products for the treatment of chronic lower limb ischemia. Full article

MicroRNAs (miRs) regulate physiological and pathological processes, including ischemia-induced angiogenesis and neovascularization. They can be transferred between cells by extracellular vesicles (EVs). However, the specific miRs that are packaged in EVs released from skeletal muscles, and how this process is modulated by ischemia, remain to be determined. We used a mouse model of hindlimb ischemia and next generation sequencing (NGS) to perform a complete profiling of miR expression and determine the effect of ischemia in skeletal muscles, and in EVs of different sizes (microvesicles (MVs) and exosomes) released from these muscles. Ischemia significantly modulated miR expression in whole muscles and EVs, increasing the levels of several miRs that can have pro-angiogenic effects (angiomiRs). We found that specific angiomiRs are selectively enriched in MVs and/or exosomes in response to ischemia. In silico approaches indicate that these miRs modulate pathways that play key roles in angiogenesis and neovascularization, including HIF1/VEGF signaling, regulation of actin cytoskeleton and focal adhesion, NOTCH, PI3K/AKT, RAS/MAPK, JAK/STAT, TGFb/SMAD signaling and the NO/cGMP/PKG pathway. Thus, we show for the first time that angiomiRs are selectively enriched in MVs and exosomes released from ischemic muscles. These angiomiRs could be targeted in order to improve the angiogenic function of EVs for potential novel therapeutic applications in patients with severe ischemic vascular diseases. Full article