Pericytes in Veterinary Species: Prospective Isolation, Characterization and Tissue Regeneration Potential

Characterization of canine adipose- and endometrium-derived Mesenchymal Stem/Stromal Cells and response to lipopolysaccharide

Mesenchymal stem/stromal cells (MSCs) are used for regenerative therapy in companion animals. Their potential was initially attributed to multipotency, but subsequent studies in rodents, humans and veterinary species evidenced that MSCs produce factors that are key mediators of immune, anti-infective and angiogenic responses, which are essential in tissue repair. MSCs preparations have been classically obtained from bone marrow and adipose tissue (AT) in live animals, what requires the use of surgical procedures. In contrast, the uterus, which is naturally exposed to external insult and infection, can be accessed nonsurgically to obtain samples, or tissues can be taken after neutering. In this study, we explored the endometrium (EM) as an alternative source of MSCs, which we compared with AT obtained from canine paired samples. Canine AT- and EM-MSCs, formed CFUs when seeded at low density, underwent tri-lineage differentiation into adipocytes, osteocytes and chondrocytes, and expressed the CD markers CD73, CD90 and CD105, at equivalent levels. The immune genes IL8, CCL2 and CCL5 were equally expressed at basal levels by both cell types. However, in the presence of the inflammatory stimulus lipopolysaccharide (LPS), expression of IL8 was higher in EM- than in AT-MSCs (p < 0.04) while the other genes were equally elevated in both cell types (p < 0.03). This contrasted with the results for CD markers, where the expression was unaltered by exposing the MSCs to LPS. Overall, the results indicate that canine EM-MSCs could serve as an alternative cell source to AT-MSCs in therapeutic applications.

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

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.

Canine umbilical cord perivascular tissue: A source of stem cells for therapy and research

There are numerous sources of multipotent mesenchymal stromal cells (MSC) with therapeutic potential, and bone marrow is the main one. However, pain, lack of donors and comorbidities associated with harvesting stimulate the search for new sources of MSCs. The aim of this work is to obtain cells from umbilical cord (UC) perivascular tissue of dogs and characterize them as MSCs. For this, the UC was obtained from therapeutic cesarean sections and submitted to enzymatic digestion. The obtained cells were subjected to growth and proliferation tests, as well as the analysis of surface markers, differentiation test in three mesenchymal lineages and analysis of differentiation markers expression. From all the UC used in this study an adherent with fibroblastoid shape cell was obtained, with an initial number of 4.8 × 10⁵ of cells. The growth curves showed a lag phase from 0 to 24 h, followed by a phase of growth of 24 to 168 h, and then phase of cell decay. The doubling time was kept around 15 h until the sixth passage, from which there were signs of cellular senescence. The differentiation assays demonstrated the ability of cells to differentiate into osteoblasts, adipocytes and chondrocytes when subjected to the induction mediums. The study of surface markers was positive for adhesion markers and negative for hematopoietic markers. Thus, cells obtained from canine UC perivascular tissue by enzymatic digestion are multipotent MSC and the protocol developed ensures the perivascular origin of these cells.