Therapeutic ultrasound (TUS) is widely used in medicine as a tool for physiotherapy for rehabilitation medicine, as lithotripsy for bladder or kidney stone destruction, and as high intensity focused ultrasound (HIFU) for ablation of tissues and cancer. Thermal and non-thermal mechanical (acoustic radiation (ARF) or cavitation forces) and the subsequent molecular and biological effects varies with tissue types, type of beam configuration and sonication parameters. Image guided Focused Ultrasound (FUS) can be used to direct thermal and mechanical energy accurately deep within the body without causing demonstrable effects to the intervening soft-tissues or bone. The mechanotransductive effects of TUS in tissues induces the molecular changes in expression of cytokines, chemokines and trophic factors (CCTF) and cellular adhesion molecules (CAM) altering the tissue microenvironment (TME) and enhance cellular homing to targeted tissues. Approximately 10 years ago, the Frank laboratory started investigating the mechanotransductive effects of pFUS in experimental models that with the goal of enhancing cellular therapy by altering the TME. We have demonstrated that pFUS exposures in combination with mesenchymal stem cells (MSC) in an acute kidney injury model induce mechanotransductive effects in the murine kidney (AKI). We investigated whether pFUS+MSC therapy could rescue established AKI. MSC administration alone at 3 days post-cisplatin, after renal functional deficits become obvious and reported significant improvement in 7-day survival of animals. Survival was further improved using pFUS+MSC. MSCs, alone or with pFUS, shifted the kidney macrophage phenotype from M1 to M2. This study shows that pFUS serves as a neoadjuvant treatment to improve MSC homing to diseased organs. We have shown that pFUS increases interferon gamma in tissue that augments the local potency of the infused MSC that home to the tissue by stimulating release of interleukin (IL) 10 from infused cells. We also established that pFUS induces an interferon gamma and IL 10 interaction in renal injury. We demonstrated that silencing IL 10 in infused MSC results in worsening of renal injury following pFUS. These results indicate that pFUS preconditions the tissues that results in increased potency of the MSC that homed to targeted tissues and has important implication for translation to clinical trials. We also developed a noninvasive model of cardiac/chest contusion with pFUS to the left ventricle that resulted in a sterile inflammatory response in the myocardium along with pulmonary hemorrhage. Magnetic resonance imaging (MRI)-guided pulsed focused ultrasound (pFUS) combined with systemic infusion of ultrasound contrast agent microbubbles (MB) causes localized blood brain barrier (BBB) disruption as evidenced by contrast-enhanced MRI, resulted in an immediate damage-associated molecular pattern (DAMP) response including elevations in heat-shock protein 70, IL-1, IL-18, and tumor necrosis factor indicative of a sterile inflammatory response (SIR) in the parenchyma. Concurrent with DAMP presentation, significant elevations in proinflammatory, anti-inflammatory, and trophic factors along with neurotrophic and neurogenesis factors were detected that lasted 24 h. The effect of pFUS+MB was due to an intravascular pressure wave from stable cavitation of the MB and resulted in TUNEL+ neurons, activated microglia and astrocytes and an innate immune response that would be compatible with mild trauma or ischemia in the brain. Six weekly courses of pFUS+MB in the brain can cause increases in hyperphosphorylated Tau in neurons as well as cortical atrophy. We also noninvasively evaluated using positron emission tomography (PET) the SIR following a single or multiple pFUS +MB to the rat brain. Positron emission tomography imaging can assess neuroinflammation, non-invasively, through targeting of the translocator protein (TSPO), 18F-DPA714, a biomarker of translocator protein (TSPO), to assess for neuroinflammatory changes an outer mitochondrial membrane receptor known to be upregulated in activated microglia and macrophages ). In the presence of inflammation, TSPO receptor increase which would result in increased uptake of 18F-DPA-714 which can cross an intact BBB. We observed 40-50% increased 18FDPA-714 binding by PET 24hr following a single sonication and 50-70% increase uptake of the radioligand 5-10 days after the second and 6th weekly pFUS+MB treatments compared to non-sonicated brain. MRI demonstrated multiple hypointense voxels on T2*w images performed at 7T consistent with microhemorrhages which may contribute the continued microglia activation. Immunohistopathology showed increase staining for microglial and astrocytic markers along with evidence of in the sonicated regions. These findings indicate that non-invasive 18F DPA 714 PET was able to detect microglia activation up to 10 days following multiple weekly sonication BBBD which would be consistent with a chronic inflammatory microenvironment and would further support the idea that the pFUS+MB approach could be used as a model of chronic traumatic encephalopathy. Ulcerative Colitis (UC) is an Inflammatory Bowel Disease (IBD) characterized by uncontrolled immune response, diarrhoea, weight loss and bloody stools, where sustained remission is not currently achievable. Dextran Sulphate Sodium (DSS)-induced colitis is an animal model that closely mimics human UC. Ultrasound (US) has been shown to prevent experimental acute kidney injury through vagus nerve (VN) stimulation and activation of the cholinergic anti-inflammatory pathway (CAIP). Since IBD patients may present dysfunctional VN activity, our aim was to determine the effects of therapeutic ultrasound (TUS) in DSS-induced colitis. Acute colitis was induced by 2% DSS in drinking water for 7days and TUS was administered to the abdominal area for 7min/day from days 4-10. US attenuated colitis by reducing clinical scores, colon shortening and histological damage, inducing proteomic tolerogenic response in the gut during the injury phase and early recovery of experimental colitis. TUS did not improve clinical and pathological outcomes in splenectomised mice. In addition, in 7nAChR (7 nicotinic acetylcholine receptor - indicator of CAIP involvement) knockout animals presented with disease worsening with TUS. Increased levels of colonic F4/80+7nAChR+ macrophages in wild type mice suggest following TUS resulted in CAIP activation and clinical/pathological improvement. These results indicate TUS improved DSS-induced colitis through stimulation of the splenic nerve along with possible contribution by VN with CAIP activation.
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