Effect of Increased Heart Rate on Sleep Quality

Effect of Increased Heart Rate on Sleep Quality Trey Wilson, Colby Beard, Makkenzi Converse-Olson, Gabriel Moura Abstract Studies have shown that sleep is now considered one of the three basic pillars of health together with diet and exercise. Poor sleep quality has a negative impact in different areas related to physical health (1). Insomnia has been alleviated significantly with resistance exercise and stretching (2). Thus, this IRB-approved study investigated the effects of increased heart rate induced by passive static stretching on sleep quality among 18-22 year old college students. Male and female college students of aged 18-22 (n=13) completed a regimen of 10, one minute passive static stretches prior to sleep for a duration of two weeks with students self monitoring heart rates. Overall sleep quality was assessed using questions adopted from the Pittsburgh Sleep Quality Index. Results of this study indicated that while the passive static stretch regimen significantly increased (p=0.000528) heart rate prior to sleeping, a positive correlation between the percent change in heart rate and percent change of subjective sleep quality scores was not demonstrated (R=0.0983). The pre and post sleep assessment scores were not significantly different for either group (experiment group p=0.424823, control group p=0.318507). Average morning heart rates (60-80 bpm = range of normal resting HR) between the two groups (p=0.437006) showed no significant difference as well. This study showed that there was a significant change in heart rate as induced by passive static stretching among the experimental group, however, there was no correlation with overall quality of sleep. Clement-Carbonell, V., Portilla-Tamarit, I., Rubio-Aparicio, M., & Madrid-Valero, J. J. (2021). Sleep Quality, Mental and Physical Health: A Differential Relationship. International journal of environmental research and public health, 18(2), 460. https://doi.org/10.3390/ijerph18020460 D\u27Aurea, C. V. R., Poyares, D., Passos, G. S., Santana, M. G., Youngstedt, S. D., Souza, A. A., Bicudo, J., Tufik, S., & de Mello, M. T. (2019). Effects of resistance exercise training and stretching on chronic insomnia. Revista brasileira de psiquiatria (Sao Paulo, Brazil : 1999), 41(1), 51–57. https://doi.org/10.1590/1516-4446-2018-003

Extended bioreactor conditioning of mononuclear cell–seeded heart valve scaffolds

The tissue-engineered heart valve may be the ideal valve replacement option but still must overcome challenges in leaflet recellularization. This study sought to investigate the potential for leaflet matrix restoration and repopulation following mononuclear cell seeding and extended periods of bioreactor conditioning. Human aortic heart valves were seeded with mononuclear cells and conditioned in a pulsatile bioreactor for 3 days, 3 weeks, or 6 weeks. The results of this study determined that a mononuclear cell population can be readily localized within the leaflet tissue in as little as 3 days. Furthermore, as extended bioreactor condition continued to the 3- and 6-week time points, the mesenchymal stem cell subfraction proliferated and appeared to become the predominant cell phenotype. This was evident through positive expression of mesenchymal stem cell markers and no expression of mononuclear cell markers observed by immunohistochemistry in the 3- and 6-week groups. In addition, cells in the 3- and 6-week groups exhibited an up-regulation of mesenchymal stem cell–associated genes ( THY1, NT5E , and ITGB1 ) and a down-regulation of mononuclear cell–associated genes ( CD14, ICAM1 , and PECAM1 ) compared to the initial seeded cell population. However, repopulation of the leaflet interstitium was less extensive than anticipated. Valves in the 6-week time point also exhibited retracted leaflets. Thus, while the 3-week bioreactor-conditioning period used in this study may hold some promise, a bioreactor-conditioning period of 6 weeks is not a viable option for clinical translation due to the negative impact on valve performance

Recellularization of decellularized heart valves: Progress toward the tissue-engineered heart valve

The tissue-engineered heart valve portends a new era in the field of valve replacement. Decellularized heart valves are of great interest as a scaffold for the tissue-engineered heart valve due to their naturally bioactive composition, clinical relevance as a stand-alone implant, and partial recellularization in vivo. However, a significant challenge remains in realizing the tissue-engineered heart valve: assuring consistent recellularization of the entire valve leaflets by phenotypically appropriate cells. Many creative strategies have pursued complete biological valve recellularization; however, identifying the optimal recellularization method, including in situ or in vitro recellularization and chemical and/or mechanical conditioning, has proven difficult. Furthermore, while many studies have focused on individual parameters for increasing valve interstitial recellularization, a general understanding of the interacting dynamics is likely necessary to achieve success. Therefore, the purpose of this review is to explore and compare the various processing strategies used for the decellularization and subsequent recellularization of tissue-engineered heart valves