John-Michael Arpino1, Zengxuan Nong1, Fuyan Li1, Hao Yin1, Nour Ghonaim1, Stephanie Milkovich1, Brittany Balint1, Caroline O'Neil1, Graham M Fraser1, Daniel Goldman1, Christopher G Ellis1, J Geoffrey Pickering2. 1. From the Robarts Research Institute (J.-M.A., Z.N., F.L., H.Y., B.B., C.O., J.G.P.), Departments of Medicine (C.G.E., J.G.P.), Medical Biophysics (J.-M.A., S.M., B.B., G.M.F., D.G., C.G.E., J.G.P.), Biochemistry (J.G.P.), and Biomedical Engineering (N.G., D.G.), Western University, London, Canada; and Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Canada (G.M.F.). 2. From the Robarts Research Institute (J.-M.A., Z.N., F.L., H.Y., B.B., C.O., J.G.P.), Departments of Medicine (C.G.E., J.G.P.), Medical Biophysics (J.-M.A., S.M., B.B., G.M.F., D.G., C.G.E., J.G.P.), Biochemistry (J.G.P.), and Biomedical Engineering (N.G., D.G.), Western University, London, Canada; and Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Canada (G.M.F.). gpickering@robarts.ca.
Abstract
RATIONALE: Angiogenesis occurs after ischemic injury to skeletal muscle, and enhancing this response has been a therapeutic goal. However, to appropriately deliver oxygen, a precisely organized and exquisitely responsive microcirculation must form. Whether these network attributes exist in a regenerated microcirculation is unknown, and methodologies for answering this have been lacking. OBJECTIVE: To develop 4-dimensional methodologies for elucidating microarchitecture and function of the reconstructed microcirculation in skeletal muscle. METHODS AND RESULTS: We established a model of complete microcirculatory regeneration after ischemia-induced obliteration in the mouse extensor digitorum longus muscle. Dynamic imaging of red blood cells revealed the regeneration of an extensive network of flowing neo-microvessels, which after 14 days structurally resembled that of uninjured muscle. However, the skeletal muscle remained hypoxic. Red blood cell transit analysis revealed slow and stalled flow in the regenerated capillaries and extensive arteriolar-venular shunting. Furthermore, spatial heterogeneity in capillary red cell transit was highly constrained, and red blood cell oxygen saturation was low and inappropriately variable. These abnormalities persisted to 120 days after injury. To determine whether the regenerated microcirculation could regulate flow, the muscle was subjected to local hypoxia using an oxygen-permeable membrane. Hypoxia promptly increased red cell velocity and flux in control capillaries, but in neocapillaries, the response was blunted. Three-dimensional confocal imaging revealed that neoarterioles were aberrantly covered by smooth muscle cells, with increased interprocess spacing and haphazard actin microfilament bundles. CONCLUSIONS: Despite robust neovascularization, the microcirculation formed by regenerative angiogenesis in skeletal muscle is profoundly flawed in both structure and function, with no evidence for normalizing over time. This network-level dysfunction must be recognized and overcome to advance regenerative approaches for ischemic disease.
RATIONALE: Angiogenesis occurs after ischemic injury to skeletal muscle, and enhancing this response has been a therapeutic goal. However, to appropriately deliver oxygen, a precisely organized and exquisitely responsive microcirculation must form. Whether these network attributes exist in a regenerated microcirculation is unknown, and methodologies for answering this have been lacking. OBJECTIVE: To develop 4-dimensional methodologies for elucidating microarchitecture and function of the reconstructed microcirculation in skeletal muscle. METHODS AND RESULTS: We established a model of complete microcirculatory regeneration after ischemia-induced obliteration in the mouse extensor digitorum longus muscle. Dynamic imaging of red blood cells revealed the regeneration of an extensive network of flowing neo-microvessels, which after 14 days structurally resembled that of uninjured muscle. However, the skeletal muscle remained hypoxic. Red blood cell transit analysis revealed slow and stalled flow in the regenerated capillaries and extensive arteriolar-venular shunting. Furthermore, spatial heterogeneity in capillary red cell transit was highly constrained, and red blood cell oxygen saturation was low and inappropriately variable. These abnormalities persisted to 120 days after injury. To determine whether the regenerated microcirculation could regulate flow, the muscle was subjected to local hypoxia using an oxygen-permeable membrane. Hypoxia promptly increased red cell velocity and flux in control capillaries, but in neocapillaries, the response was blunted. Three-dimensional confocal imaging revealed that neoarterioles were aberrantly covered by smooth muscle cells, with increased interprocess spacing and haphazard actin microfilament bundles. CONCLUSIONS: Despite robust neovascularization, the microcirculation formed by regenerative angiogenesis in skeletal muscle is profoundly flawed in both structure and function, with no evidence for normalizing over time. This network-level dysfunction must be recognized and overcome to advance regenerative approaches for ischemic disease.
Authors: Nicole L Jacobsen; Charles E Norton; Rebecca L Shaw; D D W Cornelison; Steven S Segal Journal: J Physiol Date: 2021-12-08 Impact factor: 5.182
Authors: Kyoungrae Kim; Bohyun Ro; Frederick W Damen; Daniel P Gramling; Trevor D Lehr; Qifan Song; Craig J Goergen; Bruno T Roseguini Journal: J Appl Physiol (1985) Date: 2020-11-12
Authors: Jacqueline Chevalier; Hao Yin; John-Michael Arpino; Caroline O'Neil; Zengxuan Nong; Kevin J Gilmore; Jason J Lee; Emma Prescott; Matthew Hewak; Charles L Rice; Luc Dubois; Adam H Power; Douglas W Hamilton; J Geoffrey Pickering Journal: iScience Date: 2020-06-06
Authors: Anna Henry Borton; Bryan L Benson; Lee E Neilson; Ashley Saunders; M Amer Alaiti; Alex Y Huang; Mukesh K Jain; Aaron Proweller; Diana L Ramirez-Bergeron Journal: J Am Heart Assoc Date: 2018-06-01 Impact factor: 5.501