Progress toward an ambulatory pump-lung

ObjectivesCurrently available therapies for acute and chronic lung diseases have not been effective and have various problems associated with the technologies used. We present a novel active mixing pump-lung with the goal of providing total respiratory support to ambulatory patients.MethodsThe pump-lung is based on the concept of active mixing oxygenation within a constrained vortex. The rotation of hollow-fiber membranes disrupts the concentration boundary layer, increasing gas exchange efficiency, and simultaneously pumps the blood. Consequently, the amount of membranes required to achieve gas transfer sufficient for total respiratory support is considerably small. A series of studies, including computational design, experimental bench testing, and in vivo animal experiments, have been performed to implement this concept into a viable artificial pump-lung device.ResultsA series of pump-lung prototypes with a membrane surface area of 0.17 to 0.5 m2 were designed and characterized in vitro with bovine blood, demonstrating extremely high gas exchange efficiency. The prototype with a gas exchange surface area of 0.5 m2 was evaluated in calves. The device provided oxygen transfer of approximately 115 mL/min for respiratory support of an animal for up to 5 days.ConclusionsProgress to date suggests a high likelihood of success for an extracorporeal shorter-term lung that can be switched in and out like dialysis devices. Our device is unique in that it incorporates an integrated pumping and active mixing principle for excellent gas transfer and eliminates the need of the native right ventricle’s ability to power blood through the artificial and natural lungs

Extracorporeal Membrane Oxygenation (ECMO) for Long-Term Support: Recent Advances

Considerable progress has been made in component technology, circuitry, and clinical practice related to extracorporeal membrane oxygenation (ECMO). These advances allow prolonged support with fewer complications when compared to the past eras. Long-term support cases were frequently reported with indications including respiratory failure, cardiac failure, bridge to transplantation, extracorporeal cardiopulmonary resuscitation (ECPR), and even ambulatory extracorporeal membrane oxygenation (ECMO) support. The common complications associated with ECMO, including thrombosis, hemorrhage, nosocomial infection, neurological injury, vessel injury, multiple organ failure and mechanical failure, and the disease process of patients remain limiting factors. In spite of the complications, ECMO remains the only possible option in treatments for patients requiring long-term respiratory or cardiopulmonary support. In this chapter, the recent advances in long-term ECMO support are reviewed. Clinical etiology of patients placed on long-term ECMO support, the various circuit configurations, clinical and technical issues, management aspects, and clinical outcomes are discussed

Regional remodeling strain and its association with myocardial apoptosis after myocardial infarction in an ovine model

ObjectiveProgressive left ventricular remodeling after myocardial infarction has been viewed as an important contributor to progressive heart failure. The objective of this study was to investigate the relationship between myocardial apoptosis and strain during progressive cardiac remodeling.MethodsBefore creation of an anterolateral left ventricular infarction by ligation of diagonal arteries, 16 sonomicrometry transducers were placed in the left ventricular free wall of 8 sheep to assess regional deformation in the infarct, adjacent, and normally perfused remote myocardial regions over 8 weeks' duration. Hemodynamic, echocardiographic and sonomicrometric data were collected before infarction and then 30 minutes and 2, 6, and 8 weeks after infarction. At the end of the study, regional myocardial tissues were collected for apoptotic signaling proteins.ResultsAt terminal study, an increase in left ventricular end-diastolic pressure of 8.1 ± 0.1 mm Hg, a decrease in ejection fraction from 54.19% ± 5.68% to 30.55% ± 2.72%, and an end-diastolic volume increase of 46.08 ± 5.02 mL as compared with the preinfarct values were observed. The fractional contraction at terminal study correlated with the relative abundance of apoptotic protein expressions: cytochrome c (r2 = 0.02, P < .05), mitochondrial Bax (r2 = 0.27, P < .05), caspase-3 (r2 = 0.31, P < .05), and poly (adenosine diphosphate–ribose) polymerase (r2 = 0.30, P < .05). These myocardial apoptotic activities also correlated with remodeling strain: cytochrome c (r2 = 0.02, P < .05), mitochondrial Bax (r2 = 0.28, P < .05), caspase-3 (r2 = 0.43, P < .05), and poly (adenosine diphosphate–ribose) polymerase (r2 = 0.37, P < .05).ConclusionIncrease in regional remodeling strain led to an increase in myocardial apoptosis and regional contractile dysfunction in heart failure

Components of the Hematopoietic Compartments in Tumor Stroma and Tumor-Bearing Mice

Solid tumors are composed of cancerous cells and non-cancerous stroma. A better understanding of the tumor stroma could lead to new therapeutic applications. However, the exact compositions and functions of the tumor stroma are still largely unknown. Here, using a Lewis lung carcinoma implantation mouse model, we examined the hematopoietic compartments in tumor stroma and tumor-bearing mice. Different lineages of differentiated hematopoietic cells existed in tumor stroma with the percentage of myeloid cells increasing and the percentage of lymphoid and erythroid cells decreasing over time. Using bone marrow reconstitution analysis, we showed that the tumor stroma also contained functional hematopoietic stem cells. All hematopoietic cells in the tumor stroma originated from bone marrow. In the bone marrow and peripheral blood of tumor-bearing mice, myeloid populations increased and lymphoid and erythroid populations decreased and numbers of hematopoietic stem cells markedly increased with time. To investigate the function of hematopoietic cells in tumor stroma, we co-implanted various types of hematopoietic cells with cancer cells. We found that total hematopoietic cells in the tumor stroma promoted tumor development. Furthermore, the growth of the primary implanted Lewis lung carcinomas and their metastasis were significantly decreased in mice reconstituted with IGF type I receptor-deficient hematopoietic stem cells, indicating that IGF signaling in the hematopoietic tumor stroma supports tumor outgrowth. These results reveal that hematopoietic cells in the tumor stroma regulate tumor development and that tumor progression significantly alters the host hematopoietic compartment

Kinetic Theory Approach to Modeling of Cellular Repair Mechanisms under Genome Stress

Under acute perturbations from outer environment, a normal cell can trigger cellular self-defense mechanism in response to genome stress. To investigate the kinetics of cellular self-repair process at single cell level further, a model of DNA damage generating and repair is proposed under acute Ion Radiation (IR) by using mathematical framework of kinetic theory of active particles (KTAP). Firstly, we focus on illustrating the profile of Cellular Repair System (CRS) instituted by two sub-populations, each of which is made up of the active particles with different discrete states. Then, we implement the mathematical framework of cellular self-repair mechanism, and illustrate the dynamic processes of Double Strand Breaks (DSBs) and Repair Protein (RP) generating, DSB-protein complexes (DSBCs) synthesizing, and toxins accumulating. Finally, we roughly analyze the capability of cellular self-repair mechanism, cellular activity of transferring DNA damage, and genome stability, especially the different fates of a certain cell before and after the time thresholds of IR perturbations that a cell can tolerate maximally under different IR perturbation circumstances