Johannes Holfeld

Mechanotherapy: revisiting physical therapy and recruiting mechanobiology for a new era in medicine

It has long been thought that the effectiveness and efficiency of physical therapy would improve if our understanding of the cell biology/biochemistry that participates in mechanics could be improved. Traditional physical therapy focuses primarily on rehabilitation, but recent developments in mechanobiology that illuminated the effects of physical forces on cells and tissues have led to the realization that the old therapy model should be updated. To achieve this here, the term mechanotherapy is proposed and recent studies showing how mechanotherapies target particular cells, molecules, and tissues are reviewed. These studies show how mechanical force modulates integrin-mediated processes and other mechanosensors such as gap junctions, hemichannels, primary cilia, transient receptor potential channels (cell targeting), and intracellular mechanosignaling pathways (molecule targeting). The role of mechanical force in various therapies, including microdeformation, shockwave, tissue expansion, distraction osteogenesis, and surgical tension reduction (tissue targeting) therapies, is reviewed. This review aims to jumpstart research into this field, which promises to generate a new era of viable and novel pharmacological and engineering interventions that can overcome human diseases.

The Angiogenic Factor Secretoneurin Induces Coronary Angiogenesis in a Model of Myocardial Infarction by Stimulation of Vascular Endothelial Growth Factor Signaling in Endothelial Cells

Background—Secretoneurin is a neuropeptide located in nerve fibers along blood vessels, is upregulated by hypoxia, and induces angiogenesis. We tested the hypothesis that secretoneurin gene therapy exerts beneficial effects in a rat model of myocardial infarction and evaluated the mechanism of action on coronary endothelial cells. Methods and Results—In vivo secretoneurin improved left ventricular function, inhibited remodeling, and reduced scar formation. In the infarct border zone, secretoneurin induced coronary angiogenesis, as shown by increased density of capillaries and arteries. In vitro secretoneurin induced capillary tubes, stimulated proliferation, inhibited apoptosis, and activated Akt and extracellular signal-regulated kinase in coronary endothelial cells. Effects were abrogated by a vascular endothelial growth factor (VEGF) antibody, and secretoneurin stimulated VEGF receptors in these cells. Secretoneurin furthermore increased binding of VEGF to endothelial cells, and binding was blocked by heparinase, indicating that secretoneurin stimulates binding of VEGF to heparan sulfate proteoglycan binding sites. Additionally, secretoneurin increased binding of VEGF to its coreceptor neuropilin-1. In endothelial cells, secretoneurin also stimulated fibroblast growth factor receptor-3 and insulin-like growth factor-1 receptor, and in coronary vascular smooth muscle cells, we observed stimulation of VEGF receptor-1 and fibroblast growth factor receptor-3. Exposure of cardiac myocytes to hypoxia and ischemic heart after myocardial infarction revealed increased secretoneurin messenger RNA and protein. Conclusions—Our data show that secretoneurin acts as an endogenous stimulator of VEGF signaling in coronary endothelial cells by enhancing binding of VEGF to low-affinity binding sites and neuropilin-1 and stimulates further growth factor receptors like fibroblast growth factor receptor-3. Our in vivo findings indicate that secretoneurin may be a promising therapeutic tool in ischemic heart disease.

Direct epicardial shock wave therapy improves ventricular function and induces angiogenesis in ischemic heart failure

OBJECTIVES Direct application of low-energy unfocused shock waves induces angiogenesis in ischemic soft tissue. The potential effects of epicardial shock wave therapy applied in direct contact to ischemic myocardium are uncertain. METHODS For induction of ischemic heart failure in a rodent model, a left anterior descending artery ligation was performed in adult Sprague-Dawley rats. After 4 weeks, reoperation with (treatment group, n = 60) or without (control group, n = 60) epicardial shock wave therapy was performed. Low-energy shock waves were applied in direct contact with the infarcted myocardium (300 impulses at 0.38 mJ/m(2)). Additionally, healthy animals (n = 30) with normal myocardium were studied. Angiogenesis, ventricular function upregulation of growth factors, and brain natriuretic peptide levels were analyzed. RESULTS Histologic analysis revealed significant angiogenesis 6 weeks (treatment group: 8.2 +/- 3.7 vs control group: 2.9 +/- 1.9 vessels per field, P = .016) and 14 weeks (treatment group: 7.1 +/- 3.1 vs control group: 3.2 +/- 1.8 vessels per field, P = .011) after shock wave treatment. In the treatment group ventricular function improved throughout the follow-up period (6 weeks: 37.4% +/- 9% [P < .001] and 14 weeks: 39.5% +/- 9% [P < .001]). No improvement of ventricular function was observed in the control group (6 weeks: 28.6% +/- 5% and 14 weeks: 21.4% +/- 5%). Rat brain natriuretic peptide 45 levels were lower in the treatment group compared with those in the control group 6 and 14 weeks after treatment. Vascular endothelial growth factor, Fms-related tyrosine kinase 1, and placental growth factor levels were upregulated after 24 and 48 hours and 7 days in the treatment group. No effects on healthy myocardium were observed. CONCLUSION Direct epicardial low-energy shock wave therapy induces angiogenesis and improves ventricular function in a rodent model of ischemic heart failure.

Midterm Results of Thoracic Endovascular Aortic Repair in Patients With Aneurysms Involving the Descending Aorta Originating From Chronic Type B Dissections

BACKGROUND Midterm results of TEVAR (thoracic endovascular aortic repair) in patients with aneurysms involving the descending aorta originating from chronic type B dissections are not known. METHODS Between 2004 and 2009, 14 patients with a median age of 63 years (79% male) with this pathology were treated. Seven patients underwent supraaortic transpositions in various extents prior to TEVAR in order to gain a sufficient proximal landing zone. RESULTS Median time from dissection to treatment was 19 months (4 to 84 months). All patients had an uneventful in-hospital course. The median covered length of the aortic arch and descending aorta was 190 mm (100 to 250 mm). Primary success rate defined as absence of type Ia endoleakage was 86%. No patient, where visceral or renal vessels originated from the false or from both lumina sustained ischemic injury by TEVAR. The median follow-up period is 34 months to date (6 to 64 months). Aortic-related morbidity and mortality during follow-up was low (14%). CONCLUSIONS Midterm results of TEVAR in patients with aneurysms involving the descending aorta originating from chronic type B dissections are good. The self-expanding capability of the stent grafts is sufficient over time. However, extensive coverage of the descending aorta is warranted to achieve success. Further studies are needed to extend our knowledge in this particular subgroup of patients.

Prophylactic Low-Energy Shock Wave Therapy Improves Wound Healing After Vein Harvesting for Coronary Artery Bypass Graft Surgery: A Prospective, Randomized Trial

BACKGROUND Wound healing disorders after vein harvesting for coronary artery bypass graft surgery increase morbidity and lower patient satisfaction. Low-energy shock wave therapy (SWT) reportedly improves healing of diabetic and vascular ulcers by overexpression of vascular endothelial growth fractor and downregulation of necrosis factor kappaB. In this study, we investigate whether prophylactic low-energy SWT improves wound healing after vein harvesting for coronary artery bypass graft surgery. METHODS One hundred consecutive patients undergoing coronary artery bypass graft surgery were randomly assigned to either prophylactic low-energy SWT (n = 50) or control (n = 50). Low-energy SWT was applied to the site of vein harvesting after wound closure under sterile conditions using a commercially available SWT system (Dermagold; Tissue Regeneration Technologies, Woodstock, GA). A total of 25 impulses (0.1 mJ/mm(2); 5 Hz) were applied per centimeter wound length. Wound healing was evaluated and quantified using the ASEPSIS score. (ASEPSIS stands for Additional treatment, presence of Serous discharge, Erythema, Purulent exudate, Separation of the deep tissue, Isolation of bacteria, and duration of inpatient Stay). Patient demographics, operative data, and postoperative adverse events were monitored. RESULTS Patient characteristics and operative data including wound length (SWT 39 +/- 13 cm versus control 37 +/- 11 cm, p = 0.342) were comparable between the two groups. We observed lower ASEPSIS scores indicating improved wound healing in the SWT group (4.4 +/- 5.3) compared with the control group (11.6 +/- 8.3, p = 0.0001). Interestingly, we observed a higher incidence of wound healing disorders necessitating antibiotic treatment in the control group (22%) as compared with the SWT group (4%, p = 0.015). No SWT-associated adverse events were observed in the treatment group. CONCLUSIONS As shown in this prospective randomized study, prophylactic application of low-energy SWT improves wound healing after vein harvesting for coronary artery bypass graft surgery.

Treatment of Symptomatic Coral Reef Aorta by Endovascular Stent-Graft Placement

We report 2 patients who were referred for treatment of hemodynamically significant symptomatic stenosis of the aorta at the thoracoabdominal transition (coral reef aorta) that was causing abdominal angina and intermittent claudication. Both patients underwent successful transfemoral endovascular stent-graft placement and are free of symptoms, with regular findings at 6-month follow-up completion computed tomography scan.

Low Energy Shock Wave Therapy Induces Angiogenesis in Acute Hind-Limb Ischemia via VEGF Receptor 2 Phosphorylation

Objectives Low energy shock waves have been shown to induce angiogenesis, improve left ventricular ejection fraction and decrease angina symptoms in patients suffering from chronic ischemic heart disease. Whether there is as well an effect in acute ischemia was not yet investigated. Methods Hind-limb ischemia was induced in 10–12 weeks old male C57/Bl6 wild-type mice by excision of the left femoral artery. Animals were randomly divided in a treatment group (SWT, 300 shock waves at 0.1 mJ/mm2, 5 Hz) and untreated controls (CTR), n = 10 per group. The treatment group received shock wave therapy immediately after surgery. Results Higher gene expression and protein levels of angiogenic factors VEGF-A and PlGF, as well as their receptors Flt-1 and KDR have been found. This resulted in significantly more vessels per high-power field in SWT compared to controls. Improvement of blood perfusion in treatment animals was confirmed by laser Doppler perfusion imaging. Receptor tyrosine kinase profiler revealed significant phosphorylation of VEGF receptor 2 as an underlying mechanism of action. The effect of VEGF signaling was abolished upon incubation with a VEGFR2 inhibitor indicating that the effect is indeed VEGFR 2 dependent. Conclusions Low energy shock wave treatment induces angiogenesis in acute ischemia via VEGF receptor 2 stimulation and shows the same promising effects as known from chronic myocardial ischemia. It may therefore develop as an adjunct to the treatment armentarium of acute muscle ischemia in limbs and myocardium.

Symptomatic spinal cord malperfusion after stent-graft coverage of the entire descending aorta

OBJECTIVE The study aims to identify risk constellations for symptomatic spinal cord malperfusion in patients undergoing extensive stent-graft coverage of the thoracic aorta. METHODS From 1997 through 2009, 26 patients (mean age 70 years) underwent extensive stent-graft coverage of the thoracic aorta. Indications for stent-graft placement were atherosclerotic aneurysms (n=18) and penetrating atherosclerotic ulcers (PAUs) (n=8). In 16 patients, a re-routing procedure was required to gain sufficient proximal landing zone length. Cerebrospinal fluid (CSF) drainage was not routinely applied owing to the necessity of maintaining continuing anti-platelet therapy due to severe cardiovascular co-morbidities. RESULTS Technical success was 100%. Five patients developed symptomatic spinal cord malperfusion. All symptomatic patients had impaired spinal cord blood supply by acute or chronic occlusion of at least two major blood-supplying vascular territories of the spinal cord. Secondary CSF drainage improved neurologic symptoms in all patients without causing any anti-platelet therapy-related collateral injury. CONCLUSIONS Extensive stent-graft coverage of the entire thoracic aorta can be performed with a high rate of success. If collateral blood supply to the spinal cord is maintained, occlusion of the intercostal arteries does not cause symptomatic malperfusion. However, if acute or chronic occlusion of the subclavian, lumbar or hypogastric arteries is present, likelihood of symptomatic malperfusion dramatically increases.

Epicardial shock-wave therapy improves ventricular function in a porcine model of ischaemic heart disease.

Previously we have shown that epicardial shock‐wave therapy improves left ventricular ejection fraction (LVEF) in a rat model of myocardial infarction. In the present experiments we aimed to address the safety and efficacy of epicardial shock‐wave therapy in a preclinical large animal model and to further evaluate mechanisms of action of this novel therapy. Four weeks after left anterior descending (LAD) artery ligation in pigs, the animals underwent re‐thoracotomy with (shock‐wave group, n = 6) or without (control group, n = 5) epicardial shock waves (300 impulses at 0.38 mJ/mm2) applied to the infarcted anterior wall. Efficacy endpoints were improvement of LVEF and induction of angiogenesis 6 weeks after shock‐wave therapy. Safety endpoints were haemodynamic stability during treatment and myocardial damage. Four weeks after LAD ligation, LVEF decreased in both the shock‐wave (43 ± 3%, p < 0.001) and control (41 ± 4%, p = 0.012) groups. LVEF markedly improved in shock‐wave animals 6 weeks after treatment (62 ± 9%, p = 0.006); no improvement was observed in controls (41 ± 4%, p = 0.36), yielding a significant difference. Quantitative histology revealed significant angiogenesis 6 weeks after treatment (controls 2 ± 0.4 arterioles/high‐power field vs treatment group 9 ± 3; p = 0.004). No acute or chronic adverse effects were observed. As a potential mechanism of action in vitro experiments showed stimulation of VEGF receptors after shock‐wave treatment in human coronary artery endothelial cells. Epicardial shock‐wave treatment in a large animal model of ischaemic heart failure exerted a positive effect on LVEF improvement and did not show any adverse effects. Angiogenesis was induced by stimulation of VEGF receptors. Copyright

The early activation of toll-like receptor (TLR)-3 initiates kidney injury after ischemia and reperfusion

Acute kidney injury (AKI) is one of the most important complications in hospitalized patients and its pathomechanisms are not completely elucidated. We hypothesize that signaling via toll-like receptor (TLR)-3, a receptor that is activated upon binding of double-stranded nucleotides, might play a crucial role in the pathogenesis of AKI following ischemia and reperfusion (IR). Male adult C57Bl6 wild-type (wt) mice and TLR-3 knock-out (-/-) mice were subjected to 30 minutes bilateral selective clamping of the renal artery followed by reperfusion for 30 min 2.5h and 23.5 hours or subjected to sham procedures. TLR-3 down-stream signaling was activated already within 3 h of ischemia and reperfusion in post-ischemic kidneys of wt mice lead to impaired blood perfusion followed by a strong pro-inflammatory response with significant neutrophil invasion. In contrast, this effect was absent in TLR-3-/- mice. Moreover, the quick TLR-3 activation resulted in kidney damage that was histomorphologically associated with significantly increased apoptosis and necrosis rates in renal tubules of wt mice. This finding was confirmed by increased kidney injury marker NGAL in wt mice and a better preserved renal perfusion after IR in TLR-3-/- mice than wt mice. Overall, the absence of TLR-3 is associated with lower cumulative kidney damage and maintained renal blood perfusion within the first 24 hours of reperfusion. Thus, we conclude that TLR-3 seems to participate in the pathogenesis of early acute kidney injury.