University of Ljubljana, Faculty of Pharmacy, Chair of Clinical Biochemistry, Askerceva 7, 1000, Ljubljana, Slovenia.
Valdoltra Orthopaedic Hospital, Jadranska 31, SI-6280, Ankaran, Slovenia.
Stem Cell Res Ther. 2020 Apr 3;11(1):146. doi: 10.1186/s13287-020-01657-z.
Mesenchymal stem/stromal cells (MSCs) can replenish the aged cells of the musculoskeletal system in adult life. Stem cell exhaustion and decrease in their regenerative potential have been suggested to be hallmarks of aging. Here, we investigated whether muscle- and bone-derived MSCs of patients with osteoarthritis and osteoporosis are affected by this exhaustion, compared to healthy donors.
Patients with primary osteoarthritis, femoral neck fractures due to osteoporosis, and healthy donors (controls) were included. MSCs were isolated from the skeletal muscle and subchondral bone from each patient and compared using ex vivo and in vitro analyses, including immunophenotyping, colony-forming unit fibroblast assays, growth kinetics, cell senescence, multilineage potential, and MSC marker gene expression profiling.
Freshly isolated cells from muscle from patients with osteoarthritis showed a lower proportion of CD45/CD19/CD14/CD34-negative cells compared to patients with osteoporosis and healthy donors. Freshly isolated muscle cells from patients with osteoarthritis and osteoporosis also showed higher clonogenicity compared to healthy donors. MSCs from both tissues of osteoarthritis patients showed significantly reduced osteogenesis and MSCs from the bone also reduced adipogenesis. Chondrogenic pellet diameter was reduced in bone-derived MSCs from both patient groups compared to healthy donors. A significant positive correlation was observed between adipogenesis and CD271 expression in muscle-derived MSCs. CD73 was significantly lower in bone-derived MSCs from osteoarthritis patients, compared to osteoporosis patients. Gene expression profiling showed significantly lower expression of MSC marker gene leptin receptor, LEPR, previously identified as the major source of the bone and adipocytes in the adult bone marrow, in bone-derived MSCs from patients with osteoarthritis in comparison with osteoporotic patients and healthy donors.
Our results show deficient ex vivo and in vitro properties of both skeletal muscle- and bone-derived MSCs in osteoarthritis and osteoporosis patients, compared to healthy donors. In bone-derived MSCs from patients with osteoarthritis, we also identified a lower expression of the leptin receptor, a marker of MSCs that present a major source of MSCs in the adult bone marrow. This suggests that exhaustion of skeletal muscle- and bone-derived MSCs is a hallmark of osteoarthritis and osteoporosis, which defines the need for further clinical trials of stem cell transplantation in these patients.
间充质干细胞（MSCs）可在成年后补充骨骼肌系统的衰老细胞。干细胞耗竭和再生潜能下降被认为是衰老的标志。在这里，我们研究了与健康供体相比，患有骨关节炎和骨质疏松症的患者的肌肉和骨骼来源的 MSC 是否受到这种耗竭的影响。
纳入了原发性骨关节炎患者、骨质疏松性股骨颈骨折患者和健康供体（对照组）。从每位患者的骨骼肌和软骨下骨中分离 MSC，并通过体外和体外分析进行比较，包括免疫表型分析、成纤维细胞集落形成单位测定、生长动力学、细胞衰老、多能性和 MSC 标记基因表达谱分析。
与骨质疏松症患者和健康供体相比，骨关节炎患者肌肉中新鲜分离的细胞中 CD45/CD19/CD14/CD34-细胞的比例较低。骨关节炎和骨质疏松症患者的新鲜分离肌肉细胞的集落形成能力也高于健康供体。骨关节炎患者的两种组织来源的 MSC 的成骨能力明显降低，骨来源的 MSC 的成脂能力也降低。与健康供体相比，两组患者的骨来源 MSC 的软骨形成小球直径减小。肌肉来源 MSC 中的成脂分化与 CD271 表达呈显著正相关。与骨质疏松症患者相比，骨关节炎患者的骨来源 MSC 中的 CD73 显著降低。基因表达谱分析显示，与骨质疏松症患者和健康供体相比，骨关节炎患者的骨来源 MSC 中 MSC 标记基因瘦素受体（LEPR）的表达明显降低，LEPR 先前被鉴定为成人骨髓中骨和脂肪细胞的主要来源。
与健康供体相比，我们的研究结果表明，骨关节炎和骨质疏松症患者的骨骼肌和骨骼来源的 MSC 无论是在体外还是在体内都表现出缺陷。在骨关节炎患者的骨来源 MSC 中，我们还发现瘦素受体的表达降低，瘦素受体是 MSC 的标志物，是成人骨髓中 MSC 的主要来源。这表明骨骼肌和骨骼来源的 MSC 耗竭是骨关节炎和骨质疏松症的标志，这需要进一步对这些患者进行干细胞移植的临床试验。
