Approaches for the isolation and long-term expansion of pericytes from human and animal tissues

Abstract

Pericytes surround capillaries in every organ of the human body. They are also present around the vasa vasorum, the small blood vessels that supply the walls of larger arteries and veins. The clinical interest in pericytes is rapidly growing, with the recognition of their crucial roles in controlling vascular function and possible therapeutic applications in regenerative medicine. Nonetheless, discrepancies in methods used to define, isolate, and expand pericytes are common and may affect reproducibility. Separating pure pericyte preparations from the continuum of perivascular mesenchymal cells is challenging. Moreover, variations in functional behavior and antigenic phenotype in response to environmental stimuli make it difficult to formulate an unequivocal definition of bona fide pericytes. Very few attempts were made to develop pericytes as a clinical-grade product. Therefore, this review is devoted to appraising current methodologies’ pros and cons and proposing standardization and harmonization improvements. We highlight the importance of developing upgraded protocols to create therapeutic pericyte products according to the regulatory guidelines for clinical manufacturing. Finally, we describe how integrating RNA-seq techniques with single-cell spatial analysis, and functional assays may help realize the full potential of pericytes in health, disease, and tissue repair.

Response by Frangogiannis to Letter Regarding Article, “Cardiac Pericytes Acquire a Fibrogenic Phenotype and Contribute to Vascular Maturation After Myocardial Infarction”

“…However, we agree that spatial transcriptomic analysis to study the relation between topography and transcriptomic profile would be an extremely valuable tool to distinguish the fibrogenic matrix–producing interstitial pericytes from the mural cells that interact with the endothelium contributing to vascular maturation. We also greatly appreciate the suggestion regarding the use of human induced pluripotent stem cell–derived cardiac pericytes, 4 which along with isolated human cardiac pericytes 5 may provide valuable and translationally relevant in vitro models to dissect mechanisms of myocardial pericyte activation.…”

The fate and role of the pericytes in myocardial diseases

“…Identification of new markers (or combinations of markers) that distinguish microvascular pericytes from VSMCs could provide additional tools to gain insights into cardiac pericyte biology. Improved strategies for isolation and culture of cardiac pericytes 177 could contribute valuable and translationally relevant in vitro models to dissect regulatory molecular pathways and to study interactions between pericytes and other cell types (such as endothelial or immune cells). In addition, there is a need for systematic characterization of cardiac pericyte populations in normal and failing human hearts.…”