Myosin expression and contractile function are altered by replating stem cell-derived cardiomyocytes.

Myosin heavy chain (MyHC) is the main determinant of contractile function. Human ventricular cardiomyocytes (CMs) predominantly express the ß-isoform. We previously demonstrated that ∼80% of human embryonic stem cell-derived cardiomyocytes (hESC-CMs) express exclusively ß-MyHC after long-term culture on laminin-coated glass coverslips. Here, we investigated the impact of enzymatically detaching hESC-CMs after long-term culture and subsequently replating them for characterization of cellular function. We observed that force-related kinetic parameters, as measured in a micromechanical setup, resembled α- rather than ß-MyHC-expressing myofibrils, as well as changes in calcium transients. Single-cell immunofluorescence analysis revealed that replating hESC-CMs led to rapid upregulation of α-MyHC, as indicated by increases in exclusively α-MyHC- and in mixed α/ß-MyHC-expressing hESC-CMs. A comparable increase in heterogeneity of MyHC isoform expression was also found among individual human induced pluripotent stem cell (hiPSC)-derived CMs after replating. Changes in MyHC isoform expression and cardiomyocyte function induced by replating were reversible in the course of the second week after replating. Gene enrichment analysis based on RNA-sequencing data revealed changes in the expression profile of mechanosensation/-transduction-related genes and pathways, especially integrin-associated signaling. Accordingly, the integrin downstream mediator focal adhesion kinase (FAK) promoted ß-MyHC expression on a stiff matrix, further validating gene enrichment analysis. To conclude, detachment and replating induced substantial changes in gene expression, MyHC isoform composition, and function of long-term cultivated human stem cell-derived CMs, thus inducing alterations in mechanosensation/-transduction, that need to be considered, particularly for downstream in vitro assays.

Teaching functioning, disability and rehabilitation to first year medical students.

BACKGROUND: Many patients have disabilities; it is therefore essential that medical education includes comprehensive teaching on disability and rehabilitation. In 2006 Hannover Medical School implemented an introductory course in the curriculum for medical students, on how to communicate with persons with disability and the need for rehabilitation. The course, entitled "Introduction to medicine", has the main goals of teaching the strategy and systematic approach of medicine to solving patients' problems. METHODS: This paper describes the content, methods and outcomes of 1 of the 4 main themes of the "Introduction to medicine" course; the theme "Pain and disability", which is covered in the second week of the course. RESULTS: Evaluation of the "Pain and disability" module found that students' ratings for the category "patient involvement" were very high (93%), whereas their ratings for the category "examination of student knowledge" were low. The overall rating of the module was "good" (10.8 out of 15 points), but not "very good". CONCLUSION: The concept of the "Pain and disability" module is feasible and successful, even though it is scheduled early in the first year of the curriculum and approximately 350 students participate. Factors related to this success are: a mixture of teaching knowledge, supporting students' understanding, and applying communication and physical examination skills.