# Treatment with Sildenafil Promotes Angiogenesis and Modulates Immune Response in Ischemic Muscle Tissue **Authors:** Amelie Kuhs, Lisa Bobrowski, Katharina Elbs, Matthias Kübler, Philipp Götz, Christoph Arnholdt, Manuel Lasch, Elisabeth Deindl PMC · DOI: 10.3390/cimb48030283 · 2026-03-06 ## TL;DR Sildenafil helps regenerate ischemic muscle tissue by promoting blood vessel growth and reducing inflammation. ## Contribution This study reveals sildenafil's role in promoting angiogenesis and modulating immune responses in ischemic muscle tissue. ## Key findings - Sildenafil reduces apoptotic areas and increases capillary formation in ischemic muscle tissue. - Sildenafil decreases leukocyte count and shifts macrophage polarization toward a pro-angiogenic M2-like phenotype. ## Abstract 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. ## Linked entities - **Proteins:** PDE5A (phosphodiesterase 5A), PECAM1 (platelet and endothelial cell adhesion molecule 1), PTPRC (protein tyrosine phosphatase receptor type C), CD68 (CD68 molecule), MRC1 (mannose receptor C-type 1) - **Chemicals:** Sildenafil (PubChem CID 135398744) - **Species:** Mus musculus (taxon 10090) ## Full-text entities - **Genes:** Casp3 (caspase 3) [NCBI Gene 12367] {aka A830040C14Rik, AC-3, CASP-3, CC3, CPP-32, CPP32}, Vcam1 (vascular cell adhesion molecule 1) [NCBI Gene 22329] {aka CD106, Vcam-1}, Pik3r1 (phosphoinositide-3-kinase regulatory subunit 1) [NCBI Gene 18708] {aka PI3K, p50alpha, p55alpha, p85alpha}, C1qa (complement component 1, q subcomponent, alpha polypeptide) [NCBI Gene 12259] {aka Adic, C1q}, Nfkb1 (nuclear factor of kappa light polypeptide gene enhancer in B cells 1, p105) [NCBI Gene 18033] {aka NF-KB1, NF-kappaB, NF-kappaB1, p105, p50, p50/p105}, Pdgfd (platelet-derived growth factor, D polypeptide) [NCBI Gene 71785] {aka 1110003I09Rik}, Mrc1 (mannose receptor, C type 1) [NCBI Gene 17533] {aka CD206, MR}, Srgn (serglycin) [NCBI Gene 19073] {aka Prg, Prg1, Sgc}, Timp1 (tissue inhibitor of metalloproteinase 1) [NCBI Gene 21857] {aka Clgi, EPA, TIMP-1, TPA-S1, Timp}, Ccl2 (C-C motif chemokine ligand 2) [NCBI Gene 20296] {aka HC11, JE, MCAF, MCP-1, MCP1, SMC-CF}, Cd68 (Cd68 molecule) [NCBI Gene 287435], PDE5A (phosphodiesterase 5A) [NCBI Gene 8654] {aka CGB-PDE, CN5A, PDE5}, Il1b (interleukin 1 beta) [NCBI Gene 16176] {aka IL-1beta, Il-1b}, Mrc1 (mannose receptor, C type 1) [NCBI Gene 291327], Vasp (vasodilator-stimulated phosphoprotein) [NCBI Gene 22323], Dntt (deoxynucleotidyltransferase, terminal) [NCBI Gene 21673] {aka Tdt}, Tnf (tumor necrosis factor) [NCBI Gene 21926] {aka DIF, TNF-a, TNF-alpha, TNFSF2, TNFalpha, Tnfa}, CASP3 (caspase 3) [NCBI Gene 836] {aka CPP32, CPP32B, SCA-1}, Nos3 (nitric oxide synthase 3, endothelial cell) [NCBI Gene 18127] {aka 2310065A03Rik, Nos-3, eNOS, ecNOS}, Tymp (thymidine phosphorylase) [NCBI Gene 72962] {aka 2900072D10Rik, Ecgf1, PD-ECGF, PDECGF, Pdgfec, TP}, Pde5a (phosphodiesterase 5A, cGMP-specific) [NCBI Gene 242202] {aka Cgbpde, Cn5n, PDE5a2, Pde5, Pde5a1}, Ptprc (protein tyrosine phosphatase receptor type C) [NCBI Gene 19264] {aka B220, CD45R, Cd45, L-CA, Ly-5, Lyt-4}, Hc (hemolytic complement) [NCBI Gene 15139] {aka C5, C5a, He, Hfib2}, Fgf2 (fibroblast growth factor 2) [NCBI Gene 14173] {aka Fgf-2, Fgf2a, Fgfb, bFGF}, Il10 (interleukin 10) [NCBI Gene 16153] {aka CSIF, If2a, Il-10}, Pecam1 (platelet/endothelial cell adhesion molecule 1) [NCBI Gene 18613] {aka Cd31, PECAM-1, Pecam}, Icam1 (intercellular adhesion molecule 1) [NCBI Gene 15894] {aka CD54, Icam-1, Ly-47, MALA-2}, Ccr2 (C-C motif chemokine receptor 2) [NCBI Gene 12772] {aka Cc-ckr-2, Ccr2a, Ccr2b, Ckr2, Ckr2a, Ckr2b}, Ifng (interferon gamma) [NCBI Gene 15978] {aka IFN-g, If2f, Ifg}, Gc (vitamin D binding protein) [NCBI Gene 14473] {aka DBP, VDB}, Vegfa (vascular endothelial growth factor A) [NCBI Gene 22339] {aka L-VEGF, Vegf, Vpf}, Epas1 (endothelial PAS domain protein 1) [NCBI Gene 13819] {aka HIF-2alpha, HIF2A, HLF, HRF, MOP2, bHLHe73}, Mmp9 (matrix metallopeptidase 9) [NCBI Gene 17395] {aka B/MMP9, Clg4b, Gel B, MMP-9, pro-MMP-9}, Kdr (kinase insert domain protein receptor) [NCBI Gene 16542] {aka 6130401C07, Flk-1, Flk1, Krd-1, Ly73, VEGFR-2}, TNF (tumor necrosis factor) [NCBI Gene 7124] {aka DIF, IMD127, TNF-alpha, TNFA, TNFSF2, TNLG1F}, Il6 (interleukin 6) [NCBI Gene 16193] {aka Il-6}, Il13 (interleukin 13) [NCBI Gene 16163] {aka Il-13}, Akt1 (Akt serine/threonine kinase 1) [NCBI Gene 11651] {aka Akt, LTR-akt, PKB, PKB/Akt, PKBalpha, Rac}, Ifna (interferon alpha complex region) [NCBI Gene 111654] {aka Ifa, Ifa8}, Hif1a (hypoxia inducible factor 1, alpha subunit) [NCBI Gene 15251] {aka HIF-1-alpha, HIF1-alpha, HIF1alpha, MOP1, bHLHe78}, Il4 (interleukin 4) [NCBI Gene 16189] {aka BSF-1, Il-4}, Cxcl15 (C-X-C motif chemokine ligand 15) [NCBI Gene 20309] {aka Il8, Scyb15, lungkine, weche}, Tgfb1 (transforming growth factor, beta 1) [NCBI Gene 21803] {aka TGF-beta1, TGFbeta1, Tgfb, Tgfb-1}, Cd68 (CD68 antigen) [NCBI Gene 12514] {aka Lamp4, Scard1, gp110}, PRKG1 (protein kinase cGMP-dependent 1) [NCBI Gene 5592] {aka AAT8, PKG, PKG1, PRKG1B, PRKGR1B, cGK}, Pf4 (platelet factor 4) [NCBI Gene 56744] {aka Cxcl4, Scyb4} - **Diseases:** osteoarthritis (MESH:D010003), hindlimb ischemia (MESH:D007511), atherosclerosis (MESH:D050197), mitochondrial dysfunction (MESH:D028361), endothelial (MESH:D005642), ischemic muscle (MESH:D019042), cardiovascular complications (MESH:D002318), platelet aggregate (MESH:D001791), death (MESH:D003643), injury to (MESH:D014947), FAL (MESH:D005266), PAD (MESH:D058729), inflammation (MESH:D007249), Ischemic damage (MESH:D017202), necrosis (MESH:D009336), pulmonary hypertension (MESH:D006976), erectile dysfunction (MESH:D007172), hypertensive (MESH:D006973), hypoxic (MESH:D002534), CLTI (MESH:D000089802), IC (MESH:D007383), ischemic tissue (MESH:D017695), fibrosis (MESH:D005355), hypoxia (MESH:D000860), limb loss (MESH:D001259), femoral artery occlusion (MESH:D001157), muscle injury (MESH:D009135), Ischemic (MESH:D002545) - **Chemicals:** Alexa Fluor 647 (MESH:C569686), lipid (MESH:D008055), medetomidine (MESH:D020926), Alexa Fluor 488 (MESH:C000711379), fentanyl (MESH:D005283), Sildenafil (MESH:D000068677), adenosine (MESH:D000241), midazolam (MESH:D008874), paraformaldehyde (MESH:C003043), M1 (MESH:C400939), malondialdehyde (MESH:D008315), Triton X-100 (MESH:D017830), cGMP (MESH:D006152), dUTP (MESH:C027078), NO (MESH:D009569), 1N HCL (-), PAN (MESH:C041728), calcium (MESH:D002118), water (MESH:D014867), digoxigenin (MESH:D004076), Fluorescein (MESH:D019793), Tween-20 (MESH:D011136), LPS (MESH:D008070), sucrose (MESH:D013395), Alexa Fluor 546 (MESH:C481052), BrdU (MESH:D001973), PBS (MESH:D007854), ROS (MESH:D017382) - **Species:** Homo sapiens (human, species) [taxon 9606], Mus musculus (house mouse, species) [taxon 10090], Rattus norvegicus (brown rat, species) [taxon 10116] ## Figures 4 figures with captions in the complete paper: https://tomesphere.com/paper/PMC13024863/full.md --- Source: https://tomesphere.com/paper/PMC13024863