Donor age negatively impacts adipose tissue-derived mesenchymal stem cell expansion and differentiation

Background

Human adipose tissue is an ideal autologous source of mesenchymal stem cells (MSCs) for various regenerative medicine and tissue engineering strategies. Aged patients are one of the primary target populations for many promising applications. It has long been known that advanced age is negatively correlated with an organism’s reparative and regenerative potential, but little and conflicting information is available about the effects of age on the quality of human adipose tissue derived MSCs (hAT-MSCs).

Methods

To study the influence of age, the expansion and in vitro differentiation potential of hAT-MSCs from young (<30 years), adult (35-50 years) and aged (>60 years) individuals were investigated. MSCs were characterized for expression of the genes p16^INK4a and p21 along with measurements of population doublings (PD), superoxide dismutase (SOD) activity, cellular senescence and differentiation potential.

Results

Aged MSCs displayed senescent features when compared with cells isolated from young donors, concomitant with reduced viability and proliferation. These features were also associated with significantly reduced differentiation potential in aged MSCs compared to young MSCs.

Conclusions

In conclusion, advancing age negatively impacts stem cell function and such age related alterations may be detrimental for successful stem cell therapies.     

miR-424 negatively regulates adipogenic differentiation of human adipose tissue-derived mesenchymal stem cells

目的 研究miR-424对人脂肪源间充质干细胞(hAMSCs)向成脂分化的影响.方法 用real-time PCR检测hAMSCs成脂分化前后细胞内miR-424水平的变化.在脂质体介导下,用人工合成的miR-424模拟物转染hAMSCs提高细胞内miR-424的含量,随后对其进行成脂诱导.用油红O染色法观察细胞内脂滴形成情况,用real-time PCR和Western blot检测成脂关键转录因子PPARγ及相关标记物mRNA的表达.结果 hAMSCs成脂分化后,miR-424表达下调.与对照组细胞相比,转染miR-424模拟物的实验组细胞中miR-424含量明显升高.成脂诱导第8天油红O染色结果显示,实验组脂滴形成显著少于对照组.PPARγ和成脂相关标记物的表达量也出现下调.结论 miR-424可负向调节hAMSCs向脂肪细胞分化.     

miR-424负向调节人脂肪源间充质干细胞向成脂细胞分化

目的研究miR-424对人脂肪源间充质干细胞(hAMSCs)向成脂分化的影响。方法用real-time PCR检测hAMSCs成脂分化前后细胞内miR-424水平的变化。在脂质体介导下,用人工合成的miR-424模拟物转染hAMSCs提高细胞内miR-424的含量,随后对其进行成脂诱导。用油红O染色法观察细胞内脂滴形成情况,用real-time PCR和Western blot检测成脂关键转录因子PPARγ及相关标记物mRNA的表达。结果 hAMSCs成脂分化后,miR-424表达下调。与对照组细胞相比,转染miR-424模拟物的实验组细胞中miR-424含量明显升高。成脂诱导第8天油红O染色结果显示,实验组脂滴形成显著少于对照组。PPARγ和成脂相关标记物的表达量也出现下调。结论 miR-424可负向调节hAMSCs向脂肪细胞分化。     

差速贴壁法分离培养脂肪源间充质干细胞

目的:探讨差速贴壁法从大鼠腹股沟脂肪垫分离纯化脂肪源间充质干细胞(adipose tissue-derived mesenchymal stem cells,ADMSCs)的可行性。方法:采用差速贴壁培养法分离ADMSCs,并与普通培养法得到的ADMSCs进行表面分子CD44阳性率对比。在第2代ADMSCs中加入条件培养基进行诱导,根据条件培养基的不同分成3组:①成骨诱导组:加入成骨培养基;②成脂诱导组:加入成脂培养基;③对照组:仅加入基础培养基。成骨诱导组和对照组进行碱性磷酸酶(ALP)检测,成脂诱导组和对照组进行油红O染色检测。结果:差速贴壁培养法获得CD44阳性率更高的ADMSCs。成骨诱导组的ALP大大高于对照组,成脂诱导组油红O染色阳性,对照组油红O染色均为阴性。结论:差速贴壁培养法从大鼠腹股沟脂肪垫中分离得到高纯度ADMSCs。     

脂肪组织源性干细胞的生物学特性与多向分化潜能

回顾脂肪组织源性干细胞的生物学特性与多向分化潜能研究新进展。源于中胚层的脂肪组织源性干细胞具有自我更新及多向分化潜能，在体外适当的诱导条件下可向脂肪细胞、软骨细胞、成骨细胞、骨骼肌、心肌细胞、内皮细胞及神经细胞分化，在组织工程及基因治疗中具有良好的应用前景。对脂肪组织源性干细胞生物学特性及多向分化潜能的研究．将为脂肪组织源性干细胞成为现代组织工程学研究的理想种子细胞并最终用于以细胞为基础的临床治疗提供前提和保障。     

脂肪间充质干细胞向髓核样细胞定向分化研究

目的探讨SD大鼠来源的髓核(nucleus pulposus,NP)细胞促使脂肪间充质干细胞(adipose tissue-derived mesenchymal stem cells,AMSCs)向NP样细胞定向分化的分子机制。方法采用酶消化法取脂肪细胞,极限稀释法纯化细胞;采用组织块培养法培养NP细胞。利用流式细胞技术,免疫荧光及RT-PCR检测对AMSCs及NP细胞进行鉴定。结果 AMSCs中Sca-1和CD44的阳性率较高,而CD45和CD11b阴性,共培养组荧光强度明显亮于单纯AMSCs组,AMSCs在NP细胞的诱导下聚焦蛋白聚糖(Aggrecan)、Ⅱ型胶原蛋白(CollagenⅡ)、Sox-9等表达水平较对照组高。结论共培养环境中髓核细胞分泌的可溶性因子TGF-1能促使AMSCs向NP样细胞定向分化。     

Isolation and characterization of exosomes from adipose tissue-derived mesenchymal stem cells

Mesenchymal stem cells (MSCs) are the subject of intense research as they are a potential therapeutic tool for several clinical applications. The new MSCs action models are focused on the use of MSC-derived secretome which contains several growth factors, cytokines, microRNAs, and extracellular vesicles such as exosomes. Exosomes have recently emerged as a component with great potential involved as mediators in cellular communication. The isolation and identification of exosomes has made it possible for them to be used in cell-free therapies. The purposes of this study are: (i) to detect exosomes released into adipose-derived MSC conditioned cell culture medium, (ii) to identify exosome morphology, and (iii) to carry out a complete characterization of said exosomes. Moreover, it is aimed at determining which method for exosome isolation would be best to use. Precipitation has been identified as a highly useful method of exosome isolation since it provides higher efficiency and purity values than other methods. A broad characterization of the exosomes present in the MSC-conditioned medium was also carried out. This work fills a gap in the existing literature on bioactive molecules which have attracted a great deal of interest due to their potential use in cellular therapies.     

Influence of mechanical fluid shear stress on the osteogenic differentiation protocols for Equine adipose tissue-derived mesenchymal stem cells

Cell-based therapies have become a promising approach to promote tissue regeneration and the treatment of musculoskeletal disorders. Bone regeneration maintains bone homeostasis, mechanical stability and physical performance. Mechanical stimulation showed to induce stem cell differentiation into the osteogenic fate. However, the effect of various osteogenic protocols on the osteogenic commitment of equine adipose-derived stem cells is not fully elucidated. Here we examined the influence of fluid-based shear stress (FSS) via mechanical rocking to assess whether mechanical stimulation promotes osteogenic differentiation of equine adipose-derived stem cells (ASCs). ASCs were induced into osteogenic fate using osteogenic differentiation medium (ODM) protocol or additional supplementation of 5?mM CaCl₂ and 7.5?mM CaCl₂ protocol compared to cells cultivated in basal medium (BM) up to 21 day. The ASCs proliferation pattern was evaluated using the sulforhodamine B (SRB) protein assay. Osteogenic differentiation examined via semi-quantification of alizarin red staining (ARS) and alkaline phosphatase activity (ALP) as well as, via quantification of osteocalcin (OC), alkaline phosphatase (ALP), osteopontin (OP), and collagen type-1 (COL1) gene expression using RT-qPCR. We show that mechanical FSS increased the proliferation pattern of ASCs compared to the static conditions. Mechanical FSS together with 5?mM CaCl₂ and 7.5?mM CaCl₂ promoted osteogenic nodule formation and increased ARS intensity compared to the standard osteogenic protocols. We observed that combined mechanical FSS with ODM protocol increase ALP activity compared to static culture conditions. We report that ALP and OC osteogenic markers expression were upregulated under mechanical FSS culture condition particularly with the ODM protocol. Taken together, it can be assumed that mechanical stress using FSS promotes the efficiency of the osteogenic differentiation protocols of ASCs through independent mechanisms.     

Soluble factors-mediated immunomodulatory effects of canine adipose tissue-derived mesenchymal stem cells

Adipose tissue-derived mesenchymal stem cells (AD-MSCs), which can differentiate into several lineages, have immunomodulatory properties similar to those of bone marrow-derived MSCs. However, the specific mechanism by which the immunomodulatory effect of MSCs occurs is not clear. In this study, we isolated canine AD-MSCs (cAD-MSCs) and induced their development into adipocyte, osteocyte, and neuron-like cells. We then investigated their phenotype and cytokine expression to determine whether they were able to exert an immunomodulatory effect and what the underlying mechanisms of this effect were. cAD-MSCs expressed CD44, CD90, and MHC class I and were also partially positive for the expression of CD34; however, they did not express CD14 and CD45. In addition, they expressed the mRNA of transforming growth factor beta (TGF-beta), IL-6, IL-8, CCL2, CCL5, vascular endothelial growth factor, hepatocyte growth factor (HGF), tissue inhibitor metalloproteinase-1/2, and cyclooxygenase-2 but not that of IL-10. Further, leukocyte proliferation induced by mitogens was suppressed when they were cocultured with irradiated cAD-MSCs, as well as with culture supernatants of cAD-MSCs alone. Moreover, TNF-alpha production significantly decreased, whereas TGF-beta, IL-6, and interferon-gamma production significantly increased in cAD-MSCs that were cocultured with leukocytes. Finally, immonomodulatory factors of MSCs, such as TGF-beta, HGF, prostaglandin E2 (PGE2), and indoleamine 2, 3 dioxygenase (IDO), increased significantly in cAD-MSCs that were cocultured with leukocytes; however, the production of PGE2 and IDO showed different kinetics, and leukocyte proliferation was effectively restored by PGE2 and IDO inhibitors. Taken together, these results indicate that the immunomodulatory effects of cAD-MSCs are associated with soluble factors (TGF-beta, HGF, PGE2, and IDO). Therefore, it is suggested that cAD-MSCs have a potential therapeutic use in the treatment of immune-mediated disease.     

In vitro protection of adipose tissue-derived mesenchymal stem cells by erythropoietin

Mobilization of stem cells and their differentiation into cardiomyocytes are known to have protective effects after myocardial infarction. The integrity of transplanted mesenchymal stem cells for cardiac regeneration is dependent on cell–cell or cell–matrix interaction, which is adversely affected by reactive oxygen species in an ischemic environment. Treatment with erythropoietin was shown to protect human adipose tissue derived mesenchymal stem cells in an ischemic injury in vitro model. The analyses indicated that expression of erythropoietin receptors played a pivotal role in erythropoietin mediated cell survival. In this study, the anti-apoptotic effect of erythropoietin on stem cells was analyzed in apoptosis-induced human mesenchymal stem cells. Apoptosis was induced in cultured adult human adipose tissue derived mesenchymal stem cells by hydrogen peroxide. A group of cultured cells was also treated with recombinant human erythropoietin in a concentration of 50 ng mL⁻¹. The degree of apoptosis was analyzed by flow-cytometry and immunohistochemical staining for Caspase 3. The average percentages of apoptotic cells were significantly higher in H₂O₂-induced stem cells than in cells co-cultured with erythropoietin (63.03 ± 4.96% vs 29 ± 3.41%, p < 0.01). We conclude that preconditioning with erythropoietin suppresses apoptosis of mesenchymal stem cells and enhances their survival.     

低氧影响干细胞成骨分化的研究进展

氧稳态是机体或细胞正常功能所必需的, 低氧是人正常发育的一个重要的生理因素,并参与许多疾病的发生、发展.在骨发育过程中, 组织和细胞缺氧是经常存在的.体内生长板软骨增殖区氧浓度仅为 2%-5%, 肥大区氧浓度为 0.15%-1%[1].机体损伤后,由于损伤部位血流中断或血肿形成,造成局部氧分压降低.在骨折血流中断处,中央部位氧分压甚至降低到0%-2%[2,3].骨折修复需要机体在骨折部位重建血运,以便吸收损伤组织和转运营养物质.     

神经型钙黏蛋白对小鼠脂肪间充质干细胞的成神经作用

目的:探讨神经型钙黏蛋白(N-cadherin)在小鼠脂肪间充质干细胞(ADMSCs)成神经分化中的作用。方法;用差速培养法获取小鼠ADMSCs,传至第5代,经成神经诱导液诱导ADMSCs 7 d后,免疫荧光检测胶质纤维酸性蛋白(GFAP)、神经元特异性烯醇化酶(NSE)和微管相关蛋白2(MAP2)的表达,半定量PCR检测细胞中N-cadherin mRNA的表达;采用N-cadherin对细胞进行基因修饰,免疫荧光检测神经丝蛋白(NF)和GFAP的表达。结果:ADMSCs经成神经诱导7 d后表达GFAP、NSE和MAP2,半定量PCR结果显示,与对照组相比成神经诱导后的细胞表达N-cadherin显著增高。转染N-cadherin的N-cadherin细胞培养24 h后发出细长的突起,与相邻细胞之间形成网状连接。免疫荧光结果显示,转染后的细胞NF和GFAP表达阳性。结论:ADMSCs在体外多种作用下,具有向神经细胞分化的潜能。N-cadherin转染后能改变ADMSCs的形态,并且在ADMSCs向神经分化中发挥一定的作用。     

Chondrogenic potential of bone marrow- and adipose tissue-derived adult human mesenchymal stem cells

Regarding cartilage repair, tissue engineering is currently focusing on the use of adult mesenchymal stem cells (MSC) as an alternative to autologous chondrocytes. The potential of stem cells from various tissues to differentiate towards the chondrogenic phenotype has been investigated and it appears that the most common and studied sources are bone marrow (BM) and adipose tissue (AT) for historical and easy access reasons. In addition to three dimensional environment, the presence of member(s) of the transforming growth factor (TGF-β family and low oxygen tension have been reported to promote the in vitro differentiation of MSCs. Our work aimed at characterizing and comparing the degree of chondrogenic differentiation of MSCs isolated from BM and AT cultured in the same conditions. We also further aimed at and at determining whether hypoxia (2% oxygen) could affect the chondrogenic potential of AT-MSCs. Cells were first expanded in the presence of FGF-2, then harvested and centrifuged to allow formation of cell pellets, which were cultured in the presence of TGF-β3 and/or Bone Morphogenetic Protein-2 (BMP-2) and with 2 or 20% oxygen tension, for 24 days. Markers of the chondrocyte (COL2A1, AGC1, Sox9) and hypertrophic chondrocyte (COL10A1, MMP-13) were monitored by real-time PCR and/or by immunohistological staining. Our data show that BMP-2/TGF-β3 combination is the best culture condition to induce the chondrocyte phenotype in pellet cultures of BM and AT-MSCs. Particularly, a switch in the expression of the pre-chondrogenic type IIA form to the cartilage-specific type IIB form of COL2A1 was observed. A parallel increase in gene expression of COL10A1 and MMP-13 was also recorded. However when AT-MSCs were cultured in hypoxia, the expression of markers of hypertrophic chondrocytes decreased when BMP-2/TGF-β3 were present in the medium. Thus it seems that hypoxia participates to the control of AT-MSCs chondrogenesis. Altogether, these cellular model systems will help us to investigate further the potential of different adult stem cells for cartilage engineering.     

Collagen I gel promotes homogenous osteogenic differentiation of adipose tissue-derived mesenchymal stem cells in serum-derived albumin scaffold

Repair of bone defects is a difficult clinical problem for reconstructive surgeons. Bone tissue engineering using an appropriate scaffold with cells is a new therapy for the repair of bone defects. The aim of this study was to evaluate the in vitro osteogenesis of canine adipose tissue-derived mesenchymal stem cells (Ad-MSCs) cultured in a combination of collagen I gel and a porous serum-derived albumin scaffold. A serum-derived albumin scaffold was prepared with canine serum by cross-linking and freeze-drying procedures. Ad-MSCs were seeded into serum-derived albumin scaffolds with or without collagen I gel, and were exposed to osteogenic differentiation conditions in vitro. After 28?days of in vitro culture, the distribution and osteogenic differentiation of Ad-MSCs cultured in the scaffold were evaluated by scanning electron microscopy, histology, immunohistochemistry, alkaline phosphatase (ALP) activity assay, and calcium colorimetric assay. Ad-MSCs showed more homogeneous distribution and osteogenic differentiation in the scaffold with collagen I gel than without collagen I gel. ALP activity and extracellular matrix mineralization in the construct with type I collagen were significantly higher than in the construct without type I collagen (p?<?0.05). In conclusion, the combination of collagen I gel and the serum-derived albumin scaffold enhanced osteogenic differentiation and homogenous distribution of Ad-MSCs.     

Inflammatory conditions affect gene expression and function of human adipose tissue-derived mesenchymal stem cells

There is emerging interest in the application of mesenchymal stem cells (MSC) for the prevention and treatment of autoimmune diseases, graft‐versus‐host disease and allograft rejection. It is, however, unknown how inflammatory conditions affect phenotype and function of MSC. Adipose tissue‐derived mesenchymal stem cells (ASC) were cultured with alloactivated peripheral blood mononuclear cells (PBMC) (mixed lymphocyte reaction: MLR), with proinflammatory cytokines [interferon (IFN)‐γ, tumour necrosis factor (TNF)‐α and interleukin (IL)‐6] or under control conditions, and their full genome expression and function examined. Proinflammatory cytokines mainly increased indoleamine‐2,3‐dioxygenase expression, whereas ASC cultured with MLR showed increased expression of COX‐2, involved in prostaglandin E₂ production. Both conditions had a stimulatory, but differential, effect on the expression of proinflammatory cytokines and chemokines, while the expression of fibrotic factors was decreased only in response to proinflammatory cytokines. Functional analysis demonstrated that inflammatory conditions affected morphology and proliferation of ASC, while their differentiation capacity and production of trophic factors was unaffected. The immunosuppressive capacity of ASC was enhanced strongly under inflammatory conditions. In conclusion, ASC showed enhanced immunosuppressive capacity under inflammatory conditions, while their differentiation capacity was preserved. Therefore, in vitro preconditioning provides ASC with improved properties for immediate clinical immune therapy.     

脂肪组织来源的干细胞的研究进展

来自中胚层的脂肪组织与骨髓组织一样含有大量能自我更新和多向系分化潜能的细胞群称为脂肪干细胞。其取材方便，来源丰富，可在体外稳定增殖传代。并与骨髓间充质干细胞有相似的多向分化表面标志CD105、STRO-1以及CD166受体。研究发现它具有多向系分化潜能，除可以分化为问充质来源的脂肪、骨，软骨、脂肪以及骨骼肌、心肌等细胞，也可诱导分化为来源于外胚层的神经细胞以及具有功能性的血管内皮细胞，用以修复骨、软骨、心肌、骨骼肌、血管以及神经等组织。其具有造血支持作用以及可被逆转录病毒、腺病毒以及慢病毒较高的转染效率等优点，可以作为基因转移良好的靶细胞。因而，脂肪来源的干细胞其有望成为组织工程、细胞治疗以及基因转染良好的种子细胞。