scholarly journals Heart stem cells: hope or myth?

2021 ◽  
Vol 26 (10) ◽  
pp. 4749
Author(s):  
P. M. Dokshin ◽  
A. B. Malashicheva

The search and study of endogenous heart repair remains an urgent issue in modern regenerative medicine. It is generally accepted that the human heart has a limited regenerative potential, but recent studies show that functionally significant regeneration is possible. However, the mechanisms underlying these processes remain poorly understood. In the heart, there are populations of resident mesenchymal cells that have some properties of stem cells that carry certain markers, such as c-kit+, Sca-1, etc. The ability of these cells to differentiate directly into cardiomyocytes remains controversial, but their use in clinical trials has shown improved cardiac function in patients with myocardial infarction. Currently, approaches are being developed to use, mainly, induced pluripotent stem cells as a promising regenerative therapy, but the cardioprotective role of cardiac mesenchymal cells remains the subject of active study due to their paracrine signaling.

2019 ◽  
Vol 116 (17) ◽  
pp. 8380-8389 ◽  
Author(s):  
Ralitsa R. Madsen ◽  
Rachel G. Knox ◽  
Wayne Pearce ◽  
Saioa Lopez ◽  
Betania Mahler-Araujo ◽  
...  

ThePIK3CAgene, which encodes the p110α catalytic subunit of PI3 kinase (PI3K), is mutationally activated in cancer and in overgrowth disorders known asPIK3CA-related overgrowth spectrum (PROS). To determine the consequences of geneticPIK3CAactivation in a developmental context of relevance to both PROS and cancer, we engineered isogenic human induced pluripotent stem cells (iPSCs) with heterozygous or homozygous knockin ofPIK3CAH1047R. While heterozygous iPSCs remained largely similar to wild-type cells, homozygosity forPIK3CAH1047Rcaused widespread, cancer-like transcriptional remodeling, partial loss of epithelial morphology, up-regulation of stemness markers, and impaired differentiation to all three germ layers in vitro and in vivo. Genetic analysis ofPIK3CA-associated cancers revealed that 64% had multiple oncogenicPIK3CAcopies (39%) or additional PI3K signaling pathway-activating “hits” (25%). This contrasts with the prevailing view thatPIK3CAmutations occur heterozygously in cancer. Our findings suggest that a PI3K activity threshold determines pathological consequences of oncogenicPIK3CAactivation and provide insight into the specific role of this pathway in human pluripotent stem cells.


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