Alison Hayward

Human embryonic stem cell-derived microvascular grafts for cardiac tissue preservation after myocardial infarction

We present use of a synthetic, injectable matrix metalloproteinase (MMP)-responsive, bioactive hydrogel as an in situ forming scaffold to deliver thymosin β4 (Tβ4), a pro-angiogenic and pro-survival factor, along with vascular cells derived from human embryonic stem cells (hESC) in ischemic injuries to the heart in a rat model. The gel was found to substitute the degrading extracellular matrix in the infarcted myocardium of rats and to promote structural organization of native endothelial cells, while some of the delivered hESC-derived vascular cells formed de novo capillaries in the infarct zone. Magnetic resonance imaging (MRI) revealed that the microvascular grafts effectively preserved contractile performance 3 d and 6 wk after myocardial infarction, attenuated left ventricular dilation, and decreased infarct size as compared to infarcted rats treated with PBS injection as a control (3 d ejection fraction, + ∼7%, P < 0.001; 6 wk ejection faction, + ∼12%, P < 0.001). Elevation in vessel density was observed in response to treatment, which may be due in part to elevations in human (donor)-derived cytokines EGF, VEGF and HGF (1 d). Thus, a clinically relevant matrix for dual delivery of vascular cells and drugs may be useful in engineering sustained tissue preservation and potentially regenerating ischemic cardiac tissue.

Use of PCR and culture to detect Helicobacter pylori in naturally infected cats following triple antimicrobial therapy.

Helicobacter pylori causes gastritis and peptic ulcers and is linked to gastric cancer. Domestic cats from a commercial source were found to be naturally infected with H. pylori, and studies were undertaken to eradicate H. pylori from infected cats by using triple antimicrobial therapy. Eight cats infected with H. pylori were used in the study. Six cats received a 21-day course of oral amoxicillin, metronidazole, and omeprazole, and two cats served as controls. Two weeks and 4 weeks posttreatment (p.t.), all six treated cats were negative at several sites (saliva, gastric juice, and gastric mucosa) for H. pylori by culture. However, as determined by PCR with primers specific for the 26-kDa product, the majority of cats at 2 and 4 weeks p.t. had gastric fluid samples which were positive for H. pylori and three of three cats at 2 weeks p.t. had dental plaque which was positive for H. pylori. At 6 weeks p.t., all six cats had H. pylori-negative cultures for samples from several gastric sites taken at necropsy, and only one cat had H. pylori cultured from gastric juice. PCR analysis revealed that five of six cats had H. pylori DNA amplification products from plaque, saliva, and/or gastric fluid samples. Negative bacterial cultures for cats for which there was demonstrable PCR amplification of H. pylori DNA may reflect the inability of in vitro culture techniques to isolate small numbers of H. pylori organisms, focal colonization at sites not cultured, or a failure of the antibiotics to successfully eradicate H. pylori from extragastric sites which allowed subsequent recolonization of the stomach after cessation of therapy. Alternatively, the treatment strategy may have induced in vivo viable but nonculturable coccoid forms of H. pylori. The H. pylori cat model should allow further studies to test these hypotheses as well as the efficacies of other combined therapeutic regimens. Also, because 100% of these cats were naturally infected with H.pylori, this model should prove useful in exploring mechanisms whereby human populations in underdeveloped countries, which have H. pylori infection rates approaching 100%, have a high rate of recurrence of H. pylori infection after use of prescribed antibiotic therapies that successfully eradicate H. pylori in individuals in developed countries.

Natural and Experimental Helicobacter mustelae Reinfection Following Successful Antimicrobial Eradication in Ferrets

Background.Recrudescence or reinfection may occur after eradication of Helicobacter pylori in humans.

Development of an oral once-weekly drug delivery system for HIV antiretroviral therapy

The efficacy of antiretroviral therapy is significantly compromised by medication non-adherence. Long-acting enteral systems that can ease the burden of daily adherence have not yet been developed. Here we describe an oral dosage form composed of distinct drug–polymer matrices which achieved week-long systemic drug levels of the antiretrovirals dolutegravir, rilpivirine and cabotegravir in a pig. Simulations of viral dynamics and patient adherence patterns indicate that such systems would significantly reduce therapeutic failures and epidemiological modelling suggests that using such an intervention prophylactically could avert hundreds of thousands of new HIV cases. In sum, weekly administration of long-acting antiretrovirals via a novel oral dosage form is a promising intervention to help control the HIV epidemic worldwide.Poor adherence to daily antiretrovirals can significantly affect treatment efficacy, but oral long-acting antiretrovirals are currently lacking. Here, the authors develop a once-weekly oral dosage form for anti-HIV drugs, assess its pharmacokinetics in pigs, and model its impact on viral resistance and disease epidemics.

Vascular Regeneration by Local Growth Factor Release Is Self-Limited by Microvascular Clearance

Background— The challenge of angiogenesis science is that stable sustained vascular regeneration in humans has not been realized despite promising preclinical findings. We hypothesized that angiogenic therapies powerfully self-regulate by dynamically altering tissue characteristics. Induced neocapillaries increase drug clearance and limit tissue retention and subsequent angiogenesis even in the face of sustained delivery. Methods and Results— We quantified how capillary flow clears fibroblast growth factor after local epicardial delivery. Fibroblast growth factor spatial loading was significantly reduced with intact coronary perfusion. Penetration and retention decreased with transendothelial permeability, a trend diametrically opposite to intravascular delivery, in which factor delivery depends on vascular leak, but consistent with a continuum model of drug transport in perfused tissues. Model predictions of fibroblast growth factor sensitivity to manipulations of its diffusivity and transendothelial permeability were validated by conjugation to sucrose octasulfate. Induction of neocapillaries adds pharmacokinetic complexity. Sustained local fibroblast growth factor delivery in vivo produced a burst of neovascularization in ischemic myocardium but was followed by drug washout and a 5-fold decrease in fibroblast growth factor penetration depth. Conclusions— The very efficacy of proangiogenic compounds enhances their clearance and abrogates their pharmacological benefit. This self-limiting property of angiogenesis may explain the failures of promising proangiogenic therapies.

Flexible piezoelectric devices for gastrointestinal motility sensing

Improvements in ingestible electronics with the capacity to sense physiological and pathophysiological states have transformed the standard of care for patients. Yet, despite advances in device development, significant risks associated with solid, non-flexible gastrointestinal transiting systems remain. Here, we report the design and use of an ingestible, flexible piezoelectric device that senses mechanical deformation within the gastric cavity. We demonstrate the capabilities of the sensor in both in vitro and ex vivo simulated gastric models, quantify its key behaviours in the gastrointestinal tract using computational modelling and validate its functionality in awake and ambulating swine. Our proof-of-concept device may lead to the development of ingestible piezoelectric devices that might safely sense mechanical variations and harvest mechanical energy inside the gastrointestinal tract for the diagnosis and treatment of motility disorders, as well as for monitoring ingestion in bariatric applications.An ingestible, flexible piezoelectric sensor that senses mechanical deformations in the gastric cavity allows for the monitoring of ingestion states in the gastrointestinal tract of pigs.

An ingestible bacterial-electronic system to monitor gastrointestinal health

Using bugs in the gut to detect blood Bacteria are environmentally resilient and can be engineered to sense various biomolecules. Mimee et al. combined biosensor bacteria with a miniaturized wireless readout capsule to produce a minimally invasive device capable of in vivo biosensing in harsh, difficult-to-access environments (see the Perspective by Gibson and Burgell). The device successfully measured gastrointestinal bleeding in pigs. Science, this issue p. 915; see also p. 856 An ingestible device for sensing gut biomarkers is created by combining biological and electrical engineering approaches. Biomolecular monitoring in the gastrointestinal tract could offer rapid, precise disease detection and management but is impeded by access to the remote and complex environment. Here, we present an ingestible micro-bio-electronic device (IMBED) for in situ biomolecular detection based on environmentally resilient biosensor bacteria and miniaturized luminescence readout electronics that wirelessly communicate with an external device. As a proof of concept, we engineer heme-sensitive probiotic biosensors and demonstrate accurate diagnosis of gastrointestinal bleeding in swine. Additionally, we integrate alternative biosensors to demonstrate modularity and extensibility of the detection platform. IMBEDs enable new opportunities for gastrointestinal biomarker discovery and could transform the management and diagnosis of gastrointestinal disease.

Scalable Gastric Resident Systems for Veterinary Application

Gastric resident dosage forms have been used successfully in farm animals for the delivery of a variety of drugs helping address the challenge of extended dosing. Despite these advances, there remains a significant challenge across the range of species with large variation in body size. To address this, we investigate a scalable gastric resident platform capable of prolonged retention. We investigate prototypes in dimensions consistent with administration and retention in the stomachs of two species (rabbit and pig). We investigate sustained gastric retention of our scalable dosage form platform, and in pigs show the capacity to modulate drug release kinetics of a model drug in veterinary practice, meloxicam, with our dosage form. The ability to achieve gastric residence and thereby enable sustained drug levels across different species may have a significant impact in the welfare of animals in both research, agricultural, zoological, and clinical practice settings.

Biocompatibility, bone healing, and safety evaluation in rabbits with an IlluminOss bone stabilization system

Bone healing, biocompatibility, and safety employing the IlluminOss System (IS), comprised of an inflatable balloon filled with photopolymerizable liquid monomer, was evaluated in New Zealand white rabbits. Successful bone healing and callus remodeling over 6 months was demonstrated radiologically and histologically with IS implants in fenestrated femoral cortices. Biocompatibility was demonstrated with IS implants in brushed, flushed femoral intramedullary spaces, eliciting no adverse, local, or systemic responses and with similar biocompatibility to K‐wires in contralateral femurs up to 1 year post‐implant. Lastly simulated clinical failures demonstrated the safety of IS implants up to 1 year in the presence of liquid or polymerized polymer within the intramedullary space. Polymerized material displayed cortical bone and vasculature effects comparable to mechanical disruption of the endosteum. In the clinically unlikely scenario with no remediation or polymerization, a high dose monomer injection resulted in marked necrosis of cortical bone, as well as associated vasculature, endosteum, and bone marrow. Overall, when polymerized and hardened within bone intramedullary spaces, this light curable monomer system may provide a safe and effective method for fracture stabilization.