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To realize the therapeutic potential of mesenchymal stem cells (MSCs), we aimed to develop a method for isolating and expanding New Zealand rabbit MSCs in a great scale. Rabbit MSCs expanded under hypoxic and normoxic conditions were compared in terms of replication capacity, differentiation potential, and the capacity for allogeneic transplantation in a calvarial defect model. The cells from all tested rabbits were expanded more rapidly when plated at low-density under hypoxic conditions compared to under normoxic conditions. Moreover, cells expanded under hypoxic conditions increased in the potential of osteoblastic, adipocytic, and chondrocytic differentiation. More importantly, radiographic analysis and micro-CT measurement of bone volume revealed the hypoxic cells when transplanted in the calvarial defects of another rabbit increased in the ability to repair bone defect compared to the normoxic cells. Six weeks after allogeneic transplantation of hypoxic MSCs, histological analysis revealed a callus spanned the length of the defect, and several bone tissues spotted in the implant. At 12 weeks, new bone had formed throughout the implant. Using BrdU labeling to track the transplanted cells, the hypoxic cells were more detected in the newly formed bone compared to the normoxic cells. For defects treated with allogeneic MSCs, no adverse host response could be detected at any time-point. In conclusion, we have developed a robust method for isolation and expansion of rabbit MSCs by combining low-density with hypoxic culture, which can be applied for the design of clinical trials in allogeneic transplantation of MSCs for bone healing. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1213-1220, 2012 [ABSTRACT FROM AUTHOR]

Mammalian aging of many tissues is associated with a decline in the replicative and functional capacity of somatic stem cells. Understanding the basis of this decline is a major goal of aging research. Human bone marrow-derived multipotent stromal cells (MSCs) have been applied in the treatment of fracture nonunion. Clinical application of MSCs requires abundant cells that can be overcome by ex vivo expansion of cells, but often at the expense of stemness and differentiation potentiality. We first demonstrated that late-passage MSCs exhibited decreased proliferation capacity, reduced expression of stemness markers such as Oct-4 and Nanog, and deterioration of osteogenic potential. Further, late-passage MSCs showed increased expression of p21 (p21), an inhibitor of the cyclin-dependent kinase. Knockdown of p21 by lentivirus-mediated shRNAs against p21 in late-passage MSCs increased the proliferation capacity, the expression of Oct-4 and Nanog, and osteogenic potential compared with cells transduced with control shRNA. More importantly, reduction in p21 expression in MSCs enhanced the bone repair capacity of MSCs in a rodent calvarial defect model. Knockdown of p21 in MSCs also increased the telomerase activity and telomere length, and did not show chromosomal abnormalities or acquire transformation ability. Therefore, these data successfully demonstrate the involvement of senescence gene in the expression of stemness markers and osteogenic potential of MSCs. [ABSTRACT FROM AUTHOR]

Background: Hypertension, which might contribute the white matter hyperintensities (Alber et al., 2019), is related to a higher risk of mild cognitive impairment (MCI) (Reitz et al., 2007). Studies used diffusion tensor imaging to reveal white matter lesions. In this cross‐sectional study, we used fixel‐based analysis to investigate the influence of hypertension for white matter differences in patients with MCI. Method: The study protocol complied with the tenets of the Declaration of Helsinki and was approved by the Institutional Review Board. 80 patients with MCI (39 men and 41 girls; mean age: 68.33±7.92 years; 41 patients with hypertension), and 55 healthy control (HC, 30 boys and 25 girls; mean age: 62.02±6.99 years; 14 participants with hypertension) were recruited. MRI was performed with a 3T MR750 scanner (GE Medical Systems, Milwaukee, WI). Diffusion‐weighted images were acquired using a spin‐echo echo‐planar‐imaging sequence with TR/TE/ = 4000 ms/103.5 ms, with along 64 non‐collinear directions using b‐values of 0 and 1000 s/mm2. FBA was performed by MRtrix3 (https://github.com/MRtrix3/mrtrix3) following the recommended procedures (Raffelt et al., 2017). Fixel‐based metric, which included fiber density (FD), fiber bundle cross‐section (FC), and FDC (multiplying FD and FC) was calculated. Statistical analyses of the image were performed with the code fixelcfestat in MRtrix3 with A FWE‐corrected p < 0.05 (Nichols and Holmes, 2002). Result: The white matter difference between HC and patients with MCI with /without hypertension was performed by the comparisons of FBA metrics. In the status without hypertension, patients with MCI reduced in FC and FDC predominantly in the posterior limb and retrolenticular part of internal capsule, superior and posterior corona radiate, when compared with HC. In the status with hypertension, patients with MCI reduced in FC and FDC predominantly in the superior cerebellar peduncle, posterior limb and retrolenticular part of internal capsule, and posterior corona radiate, when compared with HC. Conclusion: This study provided a thorough fixel‐based metrics of white matter differences in patients with MCI and HC with new evidence of FD, FC, and FDC, which helped to clarify the pathological changes influenced by hypertension for specific white matter regions. [ABSTRACT FROM AUTHOR]

Mammalian aging of many tissues is associated with a decline in the replicative and functional capacity of somatic stem cells. Understanding the basis of this decline is a major goal of aging research. Human bone marrow-derived multipotent stromal cells (MSCs) have been applied in the treatment of fracture nonunion. Clinical application of MSCs requires abundant cells that can be overcome by ex vivo expansion of cells, but often at the expense of stemness and differentiation potentiality. We first demonstrated that late-passage MSCs exhibited decreased proliferation capacity, reduced expression of stemness markers such as Oct-4 and Nanog, and deterioration of osteogenic potential. Further, late-passage MSCs showed increased expression of p21(Cip1/Waf1) (p21), an inhibitor of the cyclin-dependent kinase. Knockdown of p21 by lentivirus-mediated shRNAs against p21 in late-passage MSCs increased the proliferation capacity, the expression of Oct-4 and Nanog, and osteogenic potential compared with cells transduced with control shRNA. More importantly, reduction in p21 expression in MSCs enhanced the bone repair capacity of MSCs in a rodent calvarial defect model. Knockdown of p21 in MSCs also increased the telomerase activity and telomere length, and did not show chromosomal abnormalities or acquire transformation ability. Therefore, these data successfully demonstrate the involvement of senescence gene in the expression of stemness markers and osteogenic potential of MSCs., (© 2011 The Authors. Aging Cell © 2011 Blackwell Publishing Ltd/Anatomical Society of Great Britain and Ireland.)