Molecular Profiling and Gene Banking of Rabbit EPCs Derived from Two Biological Sources

Changes in the Intracellular Composition of Macro and Microminerals After Cryopreservation of the Rabbit Stem/Progenitor Cells

Cryopreservation is a widely used method for the long-term preservation of reproductive or somatic cells. It is known that this storage method may negatively affect cell viability, proliferation, differentiation, etc. However, there is a lack of information about whether cryostorage can alter the content of intracellular minerals. Therefore, we focused this study on the analysis of the mineral composition of living cells before and after long-term cold storage. Briefly, three different primary cell lines were established from rabbits as follows: endothelial progenitor cells from peripheral blood (EPCs), endothelial progenitor cells from bone marrow (BEPCs), and mesenchymal stem cells from adipose tissue (AT-MSCs), which were cultured until passage 3 prior to cryopreservation in liquid nitrogen. Samples from freshly cultured and frozen-thawed cells were mineralized and analyzed using inductively coupled plasma-optical emission spectroscopy (ICP-OES) for the content of minerals (macro: Ca, Na, K, and Mg, and micro: Zn, Fe, Cu, Al, Co, Mn, Sr, and Ni). After cryopreservation, we found significantly decreased content of K in frozen-thawed EPCs (p < 0.01) and BEPCs (p < 0.0001) and Ca in AT-MSCs (p < 0.05), while Na was increased in frozen-thawed BEPCs (p < 0.05). Concentrations of Fe and Al were reduced significantly in frozen-thawed EPCs (both p < 0.0001) and AT-MSCs (p < 0.001 and p < 0.0001, respectively). On the contrary, Fe and Al were elevated in frozen-thawed BEPCs (p < 0.0001 and p < 0.01, respectively) together with Ni (p < 0.0001). In addition, decreased Zn (p < 0.05) was observed in cryopreserved AT-MSCs. In conclusion, the ICP-OES technique might be used to analyze the basic elemental composition of animal cells in fresh or frozen-thawed conditions. Nevertheless, additional studies are needed to reveal the possible impact of cryopreservation on cell fate by changing the content of intracellular minerals.

Rabbit Endothelial Progenitor Cells Derived From Peripheral Blood and Bone Marrow: An Ultrastructural Comparative Study

The present study was designed to compare the ultrastructure of early endothelial progenitor cells (EPCs) derived from rabbit peripheral blood (PB-EPCs) and bone marrow (BM-EPCs). After the cells had been isolated and cultivated up to passage 3, microphotographs obtained from transmission electron microscope were evaluated from qualitative and quantitative (unbiased stereological approaches) points of view. Our results revealed that both cell populations displayed almost identical ultrastructural characteristics represented by abundant cellular organelles dispersed in the cytoplasm. Moreover, the presence of very occasionally occurring mature endothelial-specific Weibel–Palade bodies (WPBs) confirmed their endothelial lineage origin. The more advanced stage of their differentiation was also demonstrated by the relatively low nucleus/cytoplasm (N/C) ratios (0.41 ± 0.19 in PB-EPCs; 0.37 ± 0.25 in BM-EPCs). Between PB-EPCs and BM-EPCs, no differences in proportions of cells occupied by nucleus (28.13 ± 8.97 versus 25.10 ± 11.48%), mitochondria (3.71 ± 1.33 versus 4.23 ± 1.00%), and lipid droplets (0.65 ± 1.01 versus 0.36 ± 0.40%), as well as in estimations of the organelles surface densities were found. The data provide the first quantitative evaluation of the organelles of interest in PB-EPCs and BM-EPCs, and they can serve as a research framework for understanding cellular function.

Secretome Analysis of Rabbit and Human Mesenchymal Stem and Endothelial Progenitor Cells: A Comparative Study

Human adipose tissue-derived mesenchymal stem cells (AT-MSCs) have been studied several years for their immunomodulatory effect through the paracrine mechanism and cytokine secretion. In combination with endothelial progenitor cells (EPCs), MSCs have great therapeutical potential for the repair of endothelium and wound healing. However, little is known about the cytokine profile of rabbit AT-MSCs or even EPCs. The aim of this study was to analyze the secretomes of these rabbit stem/progenitor cells. A large-scale human cytokine array (up to 80 cytokines) was used to identify and compare cytokines secreted into conditioned media of human and rabbit AT-MSCs as well as HUVECs and rabbit EPCs. Few cytokines were highly expressed by human AT-MSCs (TIMP-2, TIMP-1), HUVECs (MCP-1, TIMP-2, GRO, Angiogenin, IL-8, TIMP-1), or by rabbit EPCs (TIMP-2). Several cytokines have moderate expression by human (MCP-1, GRO, Angiogenin, TGF-β 2, IL-8, LIF, IL-6, Osteopontin, Osteoprotegerin) and rabbit AT-MSCs (TIMP-2, TGF-β 2, LIF, Osteopontin, IL-8, IL-5, IL-3) or by HUVECs (IL-6, MIF, TGF-β 2, GCP-2, IGFBP-2, Osteoprotegerin, EGF, LIF, PDGF-BB, MCP-3, Osteopontin, Leptin, IL-5, ENA-78, TNF-β) and rabbit EPCs (TGF-β 2, Osteopontin, GRO, LIF, IL-8, IL-5, IL-3). In conclusion, the proposed method seems to be useful for the secretome analysis of rabbit stem/progenitor cells.

SSEA-4 Antigen Is Expressed on Rabbit Lymphocyte Subsets

SSEA-4 antigen can be mainly found in embryos and embryonic stem cells. However, its expression has been observed also in adult stem and progenitor cells, or even in some differentiated cells. Moreover, we found a considerable number of SSEA-4 positive (SSEA-4+) cells within the rabbit peripheral blood and bone marrow mononuclear cells (PBMCs and BMMCs) in our previous study. Since no information about such cells can be found anywhere in the literature, the aim of this study was to identify their origin. At first, phenotypic analyses of fresh rabbit PBMCs and BMMCs were performed using flow cytometry and specific antibodies against SSEA-4 and leukocyte subsets. Then, SSEA-4+ were enriched using magnetic activated cell sorting (MACS) and analyzed for their phenotype using qPCR. We found significant SSEA-4+ cell population in PBMCs (~50%) and BMMCs (~20%). All those cells co-expressed CD45 and a majority of them also expressed B-cell marker (IgM; 50% of SSEA-4+ PBMCs and 60% of SSEA-4+ BMMCs). Increased (p < 0.05) expression of SSEA-4, CD45 and B-cell markers (IgM, CD79α and MHCII) were also noticed by qPCR in SSEA-4+ cells enriched via MACS (with efficiency over 80%). Both methods did not detect significant expression of monocyte or T-cell markers. In conclusion, SSEA-4+ cells in rabbit blood and bone marrow are of hematopoietic origin and probably belong to B-lineage cells as possessing the phenotype of B lymphocytes. However, the true function of SSEA-4 antigen in these cells should be explored by further studies.