Acoustofluidics - changing paradigm in tissue engineering, therapeutics development, and biosensing.

For more than 70 years, acoustic waves have been used to screen, diagnose, and treat patients in hundreds of medical devices. The biocompatible nature of acoustic waves, their non-invasive and contactless operation, and their compatibility with wide visualization techniques are just a few of the many features that lead to the clinical success of sound-powered devices. The development of microelectromechanical systems and fabrication technologies in the past two decades reignited the spark of acoustics in the discovery of unique microscale bio applications. Acoustofluidics, the combination of acoustic waves and fluid mechanics in the nano and micro-realm, allowed researchers to access high-resolution and controllable manipulation and sensing tools for particle separation, isolation and enrichment, patterning of cells and bioparticles, fluid handling, and point of care biosensing strategies. This versatility and attractiveness of acoustofluidics have led to the rapid expansion of platforms and methods, making it also challenging for users to select the best acoustic technology. Depending on the setup, acoustic devices can offer a diverse level of biocompatibility, throughput, versatility, and sensitivity, where each of these considerations can become the design priority based on the application. In this paper, we aim to overview the recent advancements of acoustofluidics in the multifaceted fields of regenerative medicine, therapeutic development, and diagnosis and provide researchers with the necessary information needed to choose the best-suited acoustic technology for their application. Moreover, the effect of acoustofluidic systems on phenotypic behavior of living organisms are investigated. The review starts with a brief explanation of acoustofluidic principles, the different working mechanisms, and the advantages or challenges of commonly used platforms based on the state-of-the-art design features of acoustofluidic technologies. Finally, we present an outlook of potential trends, the areas to be explored, and the challenges that need to be overcome in developing acoustofluidic platforms that can echo the clinical success of conventional ultrasound-based devices.

Enhancing metabolic activity and differentiation potential in adipose mesenchymal stem cells via high-resolution surface-acoustic-wave contactless patterning.

Acoustofluidics has shown great potential for label-free bioparticle patterning with excellent biocompatibility. Acoustofluidic patterning enables the induction of cell-cell interactions, which play fundamental roles in organogenesis and tissue development. One of the current challenges in tissue engineering is not only the control of the spatial arrangement of cells but also the preservation of cell patterns over time. In this work, we developed a standing surface acoustic wave-based platform and demonstrated its capability for the well-controlled and rapid cell patterning of adipose-derived mesenchymal stem cells in a high-density homogenous collagen hydrogel. This biocompatible hydrogel is easily UV crosslinked and can be retrieved within 3 min. Acoustic waves successfully guided the cells toward pressure nodal lines, creating a contactless alignment of cells in <5 s in culture media and <1 min in the hydrogel. The acoustically patterned cells in the hydrogel did not show a decrease in cell viability (>90%) 48 h after acoustic induction. Moreover, 45.53% and 30.85% increases in metabolic activity were observed in growth and differentiation media, respectively, on Day 7. On Day 14, a 32.03% change in metabolic activity was observed using growth media, and no significant difference was observed using differentiation media. The alkaline phosphatase activity showed an increase of 80.89% and 24.90% on Days 7 and 14, respectively, for the acoustically patterned cells in the hydrogel. These results confirm the preservation of cellular viability and improved cellular functionality using the proposed high-resolution acoustic patterning technique and introduce unique opportunities for the application of stem cell regenerative patches for the emerging field of tissue engineering.

Impacto en el patrón de atención en cirugía de cabeza y cuello y las medidas sanitarias adoptadas durante los primeros 150 días de la era COVID-19 / Impact on the pattern of care in Head and Neck Surgery and the regional and institutional policy changes adopted during the first 150 days of the COVID-19 era

Resumen Introducción: La pandemia COVID-19 generó una reestructuración en la atención quirúrgica mundialmente debido a su alta transmisibilidad y la inherente limitación de los recursos humanos y materiales disponibles. Objetivo: Describir el impacto de la pandemia COVID-19 en el Equipo de Cirugía Cabeza y Cuello del Complejo Asistencial Barros Luco Trudeau (CABL) en su ejecución clínico-quirúrgica y la secuenciación organizada de las medidas sanitarias aplicadas a lo largo del tiempo durante los primeros 150 días de iniciada la pandemia en Chile. Materiales y Método: Realizamos una revisión retrospectiva de los pacientes sometidos a cirugía y/o evaluados ambulatoriamente durante el período COVID-19 comprendido entre el 3 de marzo y el 31 de julio de 2020, comparado con el mismo intervalo de tiempo de 2019. Características clínicas y medidas sanitarias empleadas durante este período fueron sintetizadas. Resultados: Detectamos un descenso del 64% en atención ambulatoria y un descenso del 58% en la carga quirúrgica, comparado con el año 2019. Durante el período COVID-19 de 2020, un total de 61 pacientes fueron sometidos a intervención quirúrgica. La principal indicación de cirugía fue cáncer en un 75,4% (46). No se reportaron pacientes contagiados por COVID-19 en los 14 días siguientes a la hospitalización. Se discuten las consideraciones perioperatorias empleadas y restricciones nacionales/institucionales sanitarias. Conclusión: La crisis sanitaria mundial secundaria al COVID-19 generó una reducción en las atenciones ambulatorias y cirugías realizadas por Equipo de Cabeza y Cuello CABL. A pesar de las restricciones sanitarias, organizamos estratificadamente la atención para preservar la resolución de casos críticos no diferibles en cabeza y cuello.

Introduction: The COVID-19 pandemic generated a restructuring of surgical care worldwide due to the disease's high transmissibility and the inherent limitation of available human and material resources. Aim: The study's aim was to describe the impact of the COVID-19 pandemic on the head and neck surgery team at Complejo Asistencial Barros Luco Trudeau (CABL) in clinical-surgical execution and organization of sanitary sequencing measures implemented over time during the first 150 days after the pandemic started in Chile. Materials and Method: We performed a retrospective review of patients undergoing surgery or outpatient evaluation during the COVID-19 period from 03-03-2020 to 07-31-2020, compared to the same time interval in 2019. Clinical characteristics and sanitary measures used during this period were synthesized. Results: We detected a 64% decrease in outpatient care and a 58% decrease in surgical load from 2019. During the COVID-19 period of 2020, a total of 61 patients underwent surgical intervention. The main indication for surgery was cancer, in 75.4% of patients (46). COVID-19 was not reported in any patients in the 14 days following hospitalization. We discussed the perioperative considerations used and the national/institutional sanitary restrictions. Conclusions: The global health crisis to COVID-19 generated a reduction in outpatient care and surgeries performed by the CABL head and neck team. Despite health restrictions, we organized care stratified to preserve critical head and neck non-deferrable cases.

Solar Radiation as an Isolated Environmental Factor in an Experimental Mesocosm Approach for Studying Photosynthetic Acclimation of Macrocystis pyrifera (Ochrophyta).

Solar radiation effects on the ecophysiology and biochemical responses of the brown macroalga Macrocystis pyrifera (L.) C. Agardh were evaluated using a mesocosm approach in Southern Chile. Treatments with different radiation attenuations were simulated with three vertical attenuation coefficients: (1) total (Kd = 0.8 m-1), (2) attenuated (Kd = 1.2 m-1), and (3) low (Kd = 1.6 m-1) radiation levels. Nutrient concentration and temperature did not show differences under the three light conditions. Photosynthetic activity was estimated by in vivo chlorophyll a (Chla) fluorescence under the three light treatments as an isolated physical factor in both in situ solar radiation in the field. This was achieved using a pulse amplitude-modulated (PAM) fluorometera-Diving PAM (in situ). Photosynthetic activity and biochemical composition were measured in winter during two daily cycles (1DC and 2DC) in different parts of the thalli of the plant: (1) canopy zone, (2) middle zone, and (3) down zone, associated with different depths in the mesocosm system. Nevertheless, the in situ electron transport rate (ETR in situ ) was higher in the exposed thalli of the canopy zone, independent of the light treatment conditions. The concentration of phenolic compounds (PC) increases in the down zone in the first daily cycle, and it was higher in the middle zone in the second daily cycle. The Chla increased in the morning time under total and attenuated radiation in the first daily cycle. Solar radiation increasing at midday prompted the photoinhibition of photosynthesis in the canopy zone but also an increase in productivity and phenol content. Therefore, light attenuation in the water column drove key differences in the photo-physiological responses of M. pyrifera, with the highest productivity occurring in thalli positioned in the canopy zone when exposed to solar irradiance.

Chitosan Microbeads Produced by One-Step Scalable Stirred Emulsification: A Promising Process for Cell Therapy Applications.

Cell microencapsulation is a promising approach to improve cell therapy outcomes by protecting injected cells from rapid dispersion and allowing bidirectional diffusion of nutrients, oxygen, and waste that promote cell survival in the target tissues. Here, we describe a simple and scalable emulsification method to encapsulate animal cells in chitosan microbeads using thermosensitive gel formulations without any chemical modification and cross-linker. The process consists of a water-in-oil emulsion where the aqueous phase droplets contain cells (L929 fibroblasts or human mesenchymal stromal cells), chitosan acidic solution and gelling agents (sodium hydrogen carbonate and phosphate buffer or beta-glycerophosphate). The oil temperature is maintained at 37 °C, allowing rapid physical gelation of the microbeads. Alginate beads prepared with the same method were used as a control. Microbeads with a diameter of 300-450 µm were successfully produced. Chitosan and alginate (2% w/v) microbeads presented similar rigidity in compression, but chitosan microbeads endured >80% strain without rupture, while alginate microbeads presented fragile breakage at <50% strain. High cell viability and metabolic activity were observed after up to 7 days in culture for encapsulated cells. Mesenchymal stromal cells encapsulated in chitosan microbeads released higher amounts of the vascular endothelial growth factor after 24 h compared to the cells encapsulated in manually cast macrogels. Moreover, microbeads were injectable through 23G needles without significant deformation or rupture. The emulsion-generated chitosan microbeads are a promising delivery vehicle for therapeutic cells because of their cytocompatibility, biodegradation, mechanical strength, and injectability. Clinical-scale encapsulation of therapeutic cells such as mesenchymal stromal cells in chitosan microbeads can readily be achieved using this simple and scalable emulsion-based process.

Impaired cell cycle regulation of the osteoblast-related heterodimeric transcription factor Runx2-Cbfbeta in osteosarcoma cells.

Bone formation and osteoblast differentiation require the functional expression of the Runx2/Cbfbeta heterodimeric transcription factor complex. Runx2 is also a suppressor of proliferation in osteoblasts by attenuating cell cycle progression in G(1). Runx2 levels are modulated during the cell cycle, which are maximal in G(1) and minimal beyond the G(1)/S phase transition (S, G(2), and M phases). It is not known whether Cbfbeta gene expression is cell cycle controlled in preosteoblasts nor how Runx2 or Cbfbeta are regulated during the cell cycle in bone cancer cells. We investigated Runx2 and Cbfbeta gene expression during cell cycle progression in MC3T3-E1 osteoblasts, as well as ROS17/2.8 and SaOS-2 osteosarcoma cells. Runx2 protein levels are reduced as expected in MC3T3-E1 cells arrested in late G(1) (by mimosine) or M phase (by nocodazole), but not in cell cycle arrested osteosarcoma cells. Cbfbeta protein levels are cell cycle independent in both osteoblasts and osteosarcoma cells. In synchronized MC3T3-E1 osteoblasts progressing from late G1 or mitosis, Runx2 levels but not Cbfbeta levels are cell cycle regulated. However, both factors are constitutively elevated throughout the cell cycle in osteosarcoma cells. Proteasome inhibition by MG132 stabilizes Runx2 protein levels in late G(1) and S in MC3T3-E1 cells, but not in ROS17/2.8 and SaOS-2 osteosarcoma cells. Thus, proteasomal degradation of Runx2 is deregulated in osteosarcoma cells. We propose that cell cycle control of Runx2 gene expression is impaired in osteosarcomas and that this deregulation may contribute to the pathogenesis of osteosarcoma.