Fatty Acid Data Analysis Unravels Skeletal Site and Age-Specific Features of Human Bone Marrow Adiposity

As adipose tissue (AT) undergoes metabolic reprogramming with age, we investigated skeletal site-specific and age-dependent lipid profile of bone marrow adipose tissue (BMAT). Acetabular and femoral BMAT, and gluteofemoral subcutaneous adipose tissue (gfSAT) were obtained from matched osteoarthritis patients. Patients were classified into two groups: younger (≤ 60 years) and aged (>60 years) adults. BMAT and gfSAT were explored by using thin layer/gas chromatography coupled with cellular and molecular assays. Data were interpreted and visualized by applying linear discriminant analysis (LDA) and hierarchical clustering of fatty acid (FA) composition. Statistics was estimated by nonparametric tests and Spearman’s rank correlation. Analyses of total lipids revealed significantly reduced triglyceride content in femoral (fBMAT) than in acetabular BMAT (aBMAT) and gfSAT. Frequencies of spontaneously released saturated palmitic (C16:0) and stearic acids (C18:0) were higher in fBMAT than in aBMAT and gfSAT (p=0.036 and p=0.046, n=8). Cluster heatmap and LDA showed that fBMAT differed to acetabular and gfSAT, while acetabular and gfSAT were more similar in FA profiles. FA profiles of AT depots varied with patient’s age. Contribution of palmitic acid was increased in aged group in all AT depots, while stearic acid declined in aged group in BMAT compartments only. fBMAT cellularity declined with age (r=-0.675, n=14, p=0.037). Additionally, the presence of CD45-CD31-CD34+CD24+ adipogenic progenitor (stem) cells was increased in fBMAT (0.46±0.03%) when compared to aBMAT (0.21±0.01%) depot. Femoral mesenchymal stem cells displayed pronounced adipogenesis comparing to their acetabular counterparts. Our findings suggest that specific lipid profile of fBMAT imposes adipogenic commitment of stem cells within this skeletal site.Book of abstract: 4th Belgrade Bioinformatics Conference, June 19-23, 202

Mesenchymal stem cells of different origin: Comparative evaluation of proliferative capacity, telomere length and pluripotency marker expression

Aims: In vitro expansion changes replication and differentiation capacity of mesenchymal stem cells (MSCs), increasing challenges and risks, while limiting the sufficient number of MSCs required for cytotherapy. Here, we characterized and compared proliferation, differentiation, telomere length and pluripotency marker expression in MSCs of various origins. Main methods: Immunophenotyping, proliferation and differentiation assays were performed. Pluripotency marker (Nanog, Oct-4, SOX-2, SSEA-4) expression was determined by immunofluorescence. Quantitative PCR was performed for relative telomere length (RTL) analyses, while expression of relevant genes for pluripotency markers, differentiation state (Cbfa1, human placental alkaline phosphatase, peroxisome proliferator activated receptor, Sox9 and Collagen II a1), and telomerase reverse transcriptase (hTERT) was determined by semiquantitative RT-PCR. Key findings: Peripheral blood MSCs (PB-MSCs) and umbilical cord MSCs (UC-MSCs) showed the highest, while periodontal ligament MSCs (PDL-MSCs) and adipose tissue MSCs (AT-MSCs) the lowest values of both the replication potential and RTL. Although MSCs from exfoliated deciduous teeth (SHEDs), PDL-MSCs and AT-MSCs showed higher mRNA expression of pluripotency markers, all MSCs expressed pluripotency marker proteins. SHEDs and PDL-MSCs showed prominent capacity for osteogenesis, PB-MSCs and UC-MSCs showed strengthened adipogenic differentiation potential, while AT-MSCs displayed similar differentiation into both lines. Significance: The MSCs populations derived from different sources, although displaying similar phenotype, exhibited high degree of variability regarding biological properties related to their self-renewal and differentiation capacity. These data indicate that for more accurate use in cell therapy, individualities of MSCs isolated from different tissues should be identified and taken into consideration when planning their use in clinical protocols