Alteration of the Mechanotransduction Properties of Human Cardiac Progenitor Cells Isolated from Ischemic Hearts
Year: 2019
Type: dissertation
Abstract: BackgroundIschemic cardiomyopathy is characterized by loss of a large number of cardiomyocytes and pervasive fibrosis that lead to heart failure.Effective therapies are far from being approved in clinical practice, compelling heart transplantation as the unique care.Resettle lost cardiomyocytes, boosting the function of cardiac progenitor cells (CPC), is under investigation as a promising therapy, but clinically meaningful results are hampered by the pathological traits of the tissue in which CPC reside.Since cells are able to sense the external environment through the mechanotransduction process, physical and biological alterations characterizing the extracellular matrix (ECM) of the pathologic heart, might lead to an improper function of CPC. AimTo investigate if CPC isolated from ischemic hearts presents defects in mechanotransduction. Methods and ResultsCPC were obtained from healthy donors (healthy CPC) and from heart failure patients (ischemic CPC).The transcription profile of healthy and ischemic CPC was analyzed and compared identifying an imbalance in genes involved in "Focal adhesion" and "Regulation of actin cytoskeleton" that, interestingly, are very closed to mechanotransduction.To test the involvement of these pathways, cells were stained with paxillin and phalloidin, a marker respectively of focal adhesion and F-actin.Consistently, ischemic CPC displayed differences in cytoskeleton morphology and high number of focal adhesions.Given the link between mechanotransduction, stiffness and ECM, we evaluated the responses of CPC plated on a soft (16kPa), intermediate (231kPa) and very hard (in order to GPa) substrates coated with two different fibronectin (FN) concentrations (1 and 25µg/mL).Data showed that ischemic CPC resulted more spread, less polarized and with less branching, displaying moreover a partial indifference to stiffness and FN.Interestingly, atomic force microscopy measure of cell stiffness, evidenced that ischemic CPC display the same indifference to substrate rigidity.Since all these data demonstrated that ischemic CPC behave differently with respect to healthy CPC when exposed to mechanical stimuli, we decided to study, in the same conditions, the nuclear shuttling of YAP and MRTF-A, two of the best-known transducers of these stimuli into biochemical responses.Consistently with previous results, ischemic CPC are indifferent to applied stimuli since no differences in YAP and MRTF-A shuttling emerged.Moreover, in healthy CPC, but not ischemic CPC, the shuttling of YAP and MRTF-A is correlated.Finally, acting on pathways controlling YAP and MRTF-A, we found that healthy and ischemic CPC differ in pathways involved in signal transduction and in the degree of responses. ConclusionThis study demonstrated that CPC isolated from ischemic hearts are characterized by altered mechanotransduction properties.The lost link between YAP and MRTF-A shuttling with physical cues and the aberrant response to treatment, suggest that restoring those pathways could result in improved CPC function.
Language: English
Subfield: Cell Biology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W7017287358