Potential of mesenchymal stem cells in gene therapy approaches for inherited and acquired diseases

The intriguing biology of stem cells and their vast clinical potential is emerging rapidly for gene therapy. Bone marrow stem cells, including the pluripotent haematopoietic stem cells (HSCs), mesenchymal stem cells (MSCs) and possibly the multipotent adherent progenitor cells (MAPCs), are being considered as potential targets for cell and gene therapy-based approaches against a variety of different diseases. The MSCs from bone marrow are a promising target population as they are capable of differentiating along multiple lineages and, at least in vitro, have significant expansion capability. The apparently high self-renewal potential makes them strong candidates for delivering genes and restoring organ systems function. However, the high proliferative potential of MSCs, now presumed to be self-renewal, may be more apparent than real. Although expanded MSCs have great proliferation and differentiation potential in vitro, there are limitations with the biology of these cells in vivo. So far, expanded MSCs have failed to induce durable therapeutic effects expected from a true self-renewing stem cell population. The loss of in vivo self-renewal may be due to the extensive expansion of MSCs in existing in vitro expansion systems, suggesting that the original stem cell population and/or properties may no longer exist. Rather, the expanded population may indeed be heterogeneous and represents several generations of different types of mesenchymal cell progeny that have retained a limited proliferation potential and responsiveness for terminal differentiation and maturation along mesenchymal and non-mesenchymal lineages. Novel technology that allows MSCs to maintain their stem cell function in vivo is critical for distinguishing the elusive stem cell from its progenitor cell populations. The ultimate dream is to use MSCs in various forms of cellular therapies, as well as genetic tools that can be used to better understand the mechanisms leading to repair and regeneration of damaged or diseased tissues and organs.     

成人和胎儿骨髓间充质干细胞的比较研究

目的 比较成人和胎儿骨髓间充质干细胞（MSC）的表型和生物学性状差异，为临床选择使用MSC提供实验依据。方法 取正常人和胎儿骨髓单个核细胞，在SF培养基中进行MSC培养，测定生长曲线。电镜观察MSC形态，利用流式细胞仪进行SMC表型测定和细胞周期分析；SA方法测定Ⅰ，Ⅲ型胶原和vWF因子表达。通过碱性磷酸酶染色，苏丹黑染色及骨钙蛋白和脂蛋白酯酶mRNA的表达等来检测细胞向成骨，成脂肪细胞分化情况。结果 从成人和胎儿骨髓中可培养出MSC，并保持多向分化潜能。两者在细胞形态，生长特性，表面抗原表达等方面是相似的。胎儿骨髓MSC的扩增潜力及多向分化能力明显强于成人MSC。成人骨髓MSC的粘附功能则强于胎儿。结论 从成人及胎儿骨髓中可分离培养出MSC，在体外有效扩增且保持其低分化状态和多向分化能力。胎儿MSC较成人MSC更原始，具有更大的多向分化和体外扩增潜能，可作为组织工程的种子细胞；而成人MSC支持造血，促进造血功能恢复和重建造血的功能则强于胎儿，具有更广泛的临床移植应用前景。     

Co-culturing mesenchymal stem cells from bone marrow and periosteum enhances osteogenesis and neovascularization of tissue-engineered bone

Mesenchymal stem cells (MSCs) isolated from bone marrow and periosteum are often used as cellular sources for bone tissue engineering. This study showed that co‐cultured human bone marrow stem cells (hBMSCs) and periosteal‐derived stem cells (hPCs) resulted in a synergistic effect on osteogenic differentiation both in vitro and in vivo. Compared to hBMSCs and hPCs, co‐culturing MSCs showed abundant mineralization, robust calcium deposition, steadily increasing ALP activity, and upgraded mRNA expression of osteogenic specific genes (COL1A1, BMP‐2, osteopontin, osteocalcin) in vitro. Eight weeks after implantation of cellular β‐TCP scaffolds in immunodeficient mice, similar synergistic effects were confirmed during in vivo evaluation of total new bone formation, mature bone formation, and neovascularization. Based on these findings, the use of co‐cultured hBMSCs and hPCs can be recommended as a promising new approach for bone tissue engineering applications. Copyright © 2011 John Wiley & Sons, Ltd.     

骨折预处理对兔骨髓来源间充质干细胞的影响

目的探讨骨折预处理对兔骨髓来源间充质干细胞（MSC）的影响。方法将10只兔按随机数字表法分为2组,每组5只。骨折预处理组截断兔股骨骨干后采用克氏针内固定,7 d后从另一侧股骨无菌抽取骨髓1～2 mL;对照组未进行任何处理。采用全骨髓贴壁法对2组兔进行骨髓来源的间充质干细胞的原代培养、酶消化法进行人工纯化,通过形态学观察、细胞周期测定及MTT实验,研究骨折预处理对MSC的影响。结果骨折预处理后可较快地获得纯化的MSC,且MSC的增殖能力在P2、P3代时均高于对照组（均P〈0.05）;随着时间的延长,P4代时2组MSC增殖能力比较差异无统计学意义（P〉0.05）。对P4代进行细胞周期测定,骨折预处理组MSC中G0/G1期细胞为70.65%,对照组MSC中G0/G1期细胞为72.40%,2组比较差异无统计学意义（P〉0.05）。结论骨折预处理全骨髓贴壁法可在更短的时间内成功地培养出稳定的MSC,并且该细胞具有更强的增殖能力。     

大鼠骨髓间充质干细胞向神经元样细胞定向诱导分化及免疫组化鉴定

目的建立体外分离、培养大鼠骨髓间充质干细胞(MSCs)的方法,体外诱导其向神经元样细胞方向分化。方法应用细胞培养技术从大鼠股骨、胫骨中分离、纯化骨髓间充质干细胞并在体外进行培养,以形态学方法鉴定间充质干细胞,在倒置显微镜下观察细胞的形态特征,利用含10 ng/ml bFGF的LG-DMEM及含200μmol/L BHA、2%DMSO的无血清DMEM诱导其向神经元样细胞分化,并通过免疫组化方法鉴定。结果经原代及传代培养的骨髓间充质干细胞呈梭形,类似于成纤维细胞;成神经元诱导24 h后,多数MSCs变为典型的神经元样细胞,胞体向胞核收缩并有较多的长突起,免疫组化显示神经元特异性标志NSE、神经巢蛋白Nestin染色阳性。结论体外成功的进行了MSCs原代及传代培养,细胞生长稳定、增殖迅速并可多次传代,经诱导后具有向神经元样细胞分化潜能。     

Cultured cell‐derived extracellular matrices to enhance the osteogenic differentiation and angiogenic properties of human mesenchymal stem/stromal cells

Cell‐derived extracellular matrix (ECM) consists of a complex assembly of fibrillary proteins, matrix macromolecules, and associated growth factors that mimic the composition and organization of native ECM micro‐environment. Therefore, cultured cell‐derived ECM has been used as a scaffold for tissue engineering settings to create a biomimetic micro‐environment, providing physical, chemical, and mechanical cues to cells, and support cell adhesion, proliferation, migration, and differentiation. Here, we present a new strategy to produce different combinations of decellularized cultured cell‐derived ECM (dECM) obtained from different cultured cell types, namely, mesenchymal stem/stromal cells (MSCs) and human umbilical vein endothelial cells (HUVECs), as well as the coculture of MSC:HUVEC and investigate the effects of its various compositions on cell metabolic activity, osteogenic differentiation, and angiogenic properties of human bone marrow (BM)‐derived MSCs, vital features for adult bone tissue regeneration and repair. Our findings demonstrate that dECM presented higher cell metabolic activity compared with tissue culture polystyrene. More importantly, we show that MSC:HUVEC ECM enhanced the osteogenic and angiogenic potential of BM MSCs, as assessed by in vitro assays. Interestingly, MSC:HUVEC (1:3) ECM demonstrated the best angiogenic response of MSCs in the conditions tested. To the best of our knowledge, this is the first study that demonstrates that dECM derived from a coculture of MSC:HUVEC impacts the osteogenic and angiogenic capabilities of BM MSCs, suggesting the potential use of MSC:HUVEC ECM as a therapeutic product to improve clinical outcomes in bone regeneration.     

Bone marrow‐on‐a‐chip: Long‐term culture of human haematopoietic stem cells in a three‐dimensional microfluidic environment

Multipotent haematopoietic stem and progenitor cells (HSPCs) are the source for all blood cell types. The bone marrow stem cell niche in which the HSPCs are maintained is known to be vital for their maintenance. Unfortunately, to date, no in vitro model exists that accurately mimics the aspects of the bone marrow niche and simultaneously allows the long‐term culture of HSPCs. In this study, a novel three‐dimensional coculture model is presented, based on a hydroxyapatite coated zirconium oxide scaffold, comprising of human mesenchymal stromal cells (MSCs) and cord blood derived HSPCs, enabling successful HSPC culture for a time span of 28 days within the microfluidic multiorgan chip. The HSPCs were found to stay in their primitive state (CD34⁺CD38^?) and capable of granulocyte, erythrocyte, macrophage, megakaryocyte colony formation. Furthermore, a microenvironment was formed bearing molecular and structural similarity to the in vivo bone marrow niche containing extracellular matrix and signalling molecules known to play an important role in HSPC homeostasis. Here, a novel human in vitro bone marrow model is presented for the first time, capable of long‐term culture of primitive HSPCs in a microfluidic environment.     

人骨髓间充质干细胞对异体T淋巴细胞增殖的影响及机制研究

目的:探讨骨髓间充质干细胞(mesenchymalstemcells,MSCs)的免疫调节作用及可能机制。方法:从人骨髓中分离培养MSCs,并通过其形态的均一性及流式细胞术检测其表面标志以鉴定其纯度。用尼龙柱法分离异体血T淋巴细胞,用植物血凝素(PHA)刺激,再将其分别与MSCs及不同浓度MSCs培养上清(100μL和200μL)共同孵育,以单独培养的异体淋巴细胞为对照组,MTT法分别测定T细胞的增殖并计算增殖转化抑制率。结果:MSCs及MSCs培养上清均可使PHA刺激引起的异体T细胞的增殖转化受抑,MSCs组抑制率为54.9%,MSCs培养上清组(100μL和200μL)抑制率分别为21.6%和37.6%(P<0.01或P<0.05)。结论:MSCs通过细胞接触和分泌某些因子对同种异体免疫反应有负调节作用。     

Low-Intensity Pulsed Ultrasound Promotes Osteogenic Differentiation of Reamer-Irrigator-Aspirator Graft-Derived Cells in Vitro

Recently, reamer–irrigator–aspirator (RIA) systems have been increasingly used to harvest autologous bone grafts. RIA graft materials contain bone marrow, which provides a viable source to derive large numbers of mesenchymal stem cells. Low-intensity pulsed ultrasound (LIPUS) significantly accelerates the differentiation of stem cells derived from bone marrow. This in vitro study investigated the effect of LIPUS on the osteogenic activity and differentiation of RIA graft-derived cells. A small amount of RIA graft was obtained from seven patients. After the cells derived from RIA grafts were cultured, they were divided into two groups: the LIPUS and control groups. LIPUS was applied once daily for 20 min (1.5 MHz, pulse duration: 200 µs, pulse repetition rate: 1 kHz, spatial average-temporal average intensity: 30 mW/cm²). Alkaline phosphatase activity (113.4% and 130.1% on days 7 and 14), expression of osteoblast-related genes (ALP, Runx2) and mineralization (135.2% on day 21) of the RIA graft-derived cells were significantly higher in the LIPUS group than in the control group. However, LIPUS did not affect the cell proliferation of RIA graft-derived cells. This study indicates that LIPUS may enhance the healing of non-union and critical bone defects treated by autologous bone grafting using the RIA system.     

Investigation of the optimal timing for chondrogenic priming of MSCs to enhance osteogenic differentiation in vitro as a bone tissue engineering strategy

Recent in vitro tissue engineering approaches have shown that chondrogenic priming of human bone marrow mesenchymal stem cells (MSCs) can have a positive effect on osteogenesis in vivo. However, whether chondrogenic priming is an effective in vitro bone regeneration strategy is not yet known. In particular, the appropriate timing for chondrogenic priming in vitro is unknown albeit that in vivo cartilage formation persists for a specific period before bone formation. The objective of this study is to determine the optimum time for chondrogenic priming of MSCs to enhance osteogenic differentiation by MSCs in vitro. Pellets derived from murine and human MSCs were cultured in six different media groups: two control groups (chondrogenic and osteogenic) and four chondrogenic priming groups (10, 14, 21 and 28 days priming). Biochemical analyses (Hoechst, sulfate glycosaminoglycan (sGAG), Alkaline Phosphate (ALP), calcium), histology (Alcian Blue, Alizarin Red) and immunohistochemistry (collagen types I, II and X) were performed on the samples at specific times. Our results show that after 49 days the highest amount of sGAG production occurred in MSCs chondrogenically primed for 21 days and 28 days. Moreover we found that chondrogenic priming of MSCs in vitro for specific amounts of time (14 days, 21 days) can have optimum influence on their mineralization capacity and can produce a construct that is mineralized throughout the core. Determining the optimum time for chondrogenic priming to enhance osteogenic differentiation in vitro provides information that might lead to a novel regenerative treatment for large bone defects, as well as addressing the major limitation of core degradation and construct failure. Copyright © 2013 John Wiley & Sons, Ltd.     

Endothelial cells stimulate osteogenic differentiation of mesenchymal stem cells on calcium phosphate scaffolds

The interaction of mesenchymal stem cells (MSCs) with endothelium in vivo is significant for regenerative processes in organisms. To design concepts for tissue engineering for bone regeneration based on this interaction, the osteogenic differentiation of human bone marrow‐derived MSCs in a co‐culture with human dermal microvascular endothelial cells (HDMECs) was studied. The experiments were focussed on the regulation of MSCs in a co‐culture with HDMECs on different calcium phosphate scaffolds. Alkaline phosphatase (ALP) activity and mRNA expression of various osteogenic markers increased significantly when cells were co‐cultured on materials with calcium phosphate scaffolds compared to tissue culture polystyrene or when MSCs were cultured alone. In addition, it was observed that the expression of osteopontin and osteocalcin was highly sensitive to the substrate for cell adhesion. Whereas these late osteogenic markers were down‐regulated in co‐cultures on polystyrene, they were up‐regulated on calcium phosphate and moreover, were differentially expressed on the three calcium phosphate scaffolds tested. To enhance the osteogenic differentiation of MSCs in a co‐culture, direct cell‐cell interactions were required. Concerning molecular mechanisms in the interactions between both cell types, it was found that connexin 43 was expressed in contact sites and more apparently, endothelial cells grew over the MSCs, which facilitated direct cellular interactions mediated by various adhesion receptors. This study revealed significant findings for the design of implant materials suitable for regeneration of bone by stimulating the functional interaction of MSCs with endothelial cells. Copyright © 2012 John Wiley & Sons, Ltd.     

骨髓间充质干细胞对K562细胞增殖及凋亡的影响

本研究比较K562细胞与相同数量以及不同数量的人骨髓间充质干细胞（MSC）黏附培养前后K562细胞增殖、细胞周期和凋亡的变化,以探讨MSC对人白血病K562细胞生长的影响。通过建立正常人骨髓MSC的体外培养体系及其与K562细胞共培养的体系测定K562细胞的生长曲线;将不同数量的MSC与K562细胞共培养测定K562细胞的增殖率曲线;应用流式细胞术检测K562细胞周期以及凋亡的变化。结果显示：与单独K562细胞培养相比,K562细胞与相同数量MSC共培养后,生长受抑;K562细胞与不同数量MSC共培养后,MSC对K562细胞的抗增殖作用呈剂量依赖性;细胞周期分析发现,K562细胞与MSC共培养后,G0／G1期以及G2／M期的细胞增加,S期的细胞减少。共培养24、48、72小时后流式细胞仪检测发现,K562细胞的凋亡率下降。结论：正常人骨髓MSC能使导致K562细胞生长抑制,阻止K562细胞周期的运行,凋亡率下降,且在一定范围内,随着MSC数量的增加,对K562细胞的抗增殖作用增强。     

骨髓间充质干细胞向心肌样细胞分化的实验研究

目的研究5-氮胞苷（5-Aza）对培养人骨髓间充质干细胞（MSCs）的作用,并对分化后的心肌样细胞进行鉴定。方法采用密度梯度离心法分离到骨髓单个核细胞（MB-MNC）,用含200ml／L胎牛血清的低糖型DMEM培养液进行培养。采用差速贴壁法纯化MSCs,用流式细胞仪检测细胞表面抗原。以5-Aza诱导第3代MSCs 24h后,继续培养。于培养的第4周,采用免疫细胞化学方法检测肌系特异性标记抗原结合蛋白（nesmin）,RT-PCR检测心肌早期转录因子GATA-4和心肌特异性蛋白肌钙蛋白T（cTnT）。结果MSCs经5-Aza诱导分化后表达Desmin、GATA-4和cTnT,未经诱导的同培养天数的MSCs中均呈未见表达。结论MSCs经5-Aza诱导后可以表现心肌样细胞特征。     

The posibility study of human mesenchymal stem cells harvested and cultivated in vitro as seeds cells for reconstruction of throat and trachea cartilage tissue engineering

Recentlysomedatashowedthathumanmarrowtissuenotonlycontainshematopoieticstemcells,butalsocontainsabundantmes－enchymalstemcells（MSCs）．MSCshavetheabilitytodifferintoothercells．Theycanbecultured,proliferated,inducedandtransformedintoboneorcartilagetissue,sothiscanbeusedtorepairdamageofboneorcartilagetissue犤１－３犦．Butcomparedwithhematopaieticstemcellstherearen＇tabundantMSCsinbonemarrow．InthisexperimentMSCswereseparatedfrombonemarrowandpurified,andtheirproliferationandgrowthchar…     

Angiogenic and osteogenic regeneration in rats via calcium phosphate scaffold and endothelial cell co‐culture with human bone marrow mesenchymal stem cells (MSCs), human umbilical cord MSCs,human induced pluripotent stem cell‐derived MSCs and human embryonic stem cell‐derived MSCs

Angiogenesis is a limiting factor in regenerating large bone defects. The objective of this study was to investigate angiogenic and osteogenic effects of co‐culture on calcium phosphate cement (CPC) scaffold using human umbilical vein endothelial cells (hUVECs) and mesenchymal stem cells (MSCs) from different origins for the first time. hUVECs were co‐cultured with four types of cell: human umbilical cord MSCs (hUCMSCs), human bone marrow MSCs (hBMSCs) and MSCs from induced pluripotent stem cells (hiPSC‐MSCs) and embryonic stem cells (hESC‐MSCs). Constructs were implanted in 8 mm cranial defects of rats for 12 weeks. CPC without cells served as control 1. CPC with hBMSCs served as control 2. Microcapillary‐like structures were successfully formed on CPC in vitro in all four co‐cultured groups. Microcapillary lengths increased with time (p < 0.05). Osteogenic and angiogenic gene expressions were highly elevated and mineralization by co‐cultured cells increased with time (p < 0.05). New bone amount and blood vessel density of co‐cultured groups were much greater than controls (p < 0.05) in an animal study. hUVECs co‐cultured with hUCMSCs, hiPSC‐MSCs and hESC‐MSCs achieved new bone and vessel density similar to hUVECs co‐cultured with hBMSCs (p > 0.1). Therefore, hUCMSCs, hiPSC‐MSCs and hESC‐MSCs could serve as alternative cell sources to hBMSCs, which require an invasive procedure to harvest. In conclusion, this study showed for the first time that co‐cultures of hUVECs with hUCMSCs, hiPSC‐MSCs, hESC‐MSCs and hBMSCs delivered via CPC scaffold achieved excellent osteogenic and angiogenic capabilities in vivo. The novel co‐culture constructs are promising for bone reconstruction with improved angiogenesis for craniofacial/orthopaedic applications. Copyright © 2017 John Wiley & Sons, Ltd.     

Differential bone‐forming capacity of osteogenic cells from either embryonic stem cells or bone marrow‐derived mesenchymal stem cells

For more than a decade, human mesenchymal stem cells (hMSCs) have been used in bone tissue‐engineering research. More recently some of the focus in this field has shifted towards the use of embryonic stem cells. While it is well known that hMSCs are able to form bone when implanted subcutaneously in immune‐deficient mice, the osteogenic potential of embryonic stem cells has been mainly assessed in vitro. Therefore, we performed a series of studies to compare the in vitro and in vivo osteogenic capacities of human and mouse embryonic stem cells to those of hMSCs. Embryonic and mesenchymal stem cells showed all characteristic signs of osteogenic differentiation in vitro when cultured in osteogenic medium, including the deposition of a mineralized matrix and expression of genes involved in osteogenic differentiation. As such, based on the in vitro results, osteogenic ES cells could not be discriminated from osteogenic hMSCs. Nevertheless, although osteogenic hMSCs formed bone upon implantation, osteogenic cells derived from both human and mouse embryonic stem cells did not form functional bone, indicated by absence of osteocytes, bone marrow and lamellar bone. Although embryonic stem cells show all signs of osteogenic differentiation in vitro, it appears that, in contrast to mesenchymal stem cells, they do not possess the ability to form bone in vivo when a similar culture method and osteogenic differentiation protocol was applied. Copyright © 2010 John Wiley & Sons, Ltd.     

全骨髓贴壁法分离培养大鼠骨髓间充质干细胞的生物学特性及优势

背景：骨髓来源的间充质干细胞含量极低,体外纯化、扩增活性好、分化潜能高的骨髓间充质干细胞,对进一步研究至关重要。目的：进一步验证全骨髓贴壁法体外分离、培养、纯化骨髓间充质干细胞的生物学特性、表型及多向分化潜能。方法：通过全骨髓贴壁法体外分离、培养、纯化大鼠骨髓间充质干细胞,进行形态学观察,流式细胞仪检测细胞标记物表达,分别进行成骨、成脂诱导分化。结果与结论：成功纯化、扩增了高细胞活性、高分化潜能的骨髓问充质干细胞。所得细胞呈成纤维细胞样;表达CD29、CD90,不表达CD45;成骨、成脂诱导分化后,茜素红染色、油红O染色阳性。证实全骨髓贴壁法操作简单、对细胞活性损伤小,可以得到高纯度、高活性、高分化潜能、生物学形态和特征稳定的骨髓间充质干细胞。     

猪骨髓间质干细胞的分离培养及分化潜能的鉴定

目的：建立猪骨髓间质干细胞(MSCs)的体外分离培养和鉴定的方法，探讨体外培养的间充质干细胞的一些生物学特点，为利用猪的实验研究提供实验基础。方法：猪的髂嵴穿刺吸取骨髓，经密度梯度离心得到骨髓单个核细胞，接种后形成单层贴壁的成纤维样的细胞。检测细胞周期，多向诱导分化鉴定分离的细胞。结果：体外培养的原代MSCs12～14d达到融合，传代后仍具有分化成骨的能力，细胞周期显示有80％的细胞处于GO／G1期。结论：体外培养猪的MSCs具有分化成骨的潜能，生长稳定，传代后仍保持未分化状态．猪骨髓间充质干细胞分离培养体系的建立为基础研究和组织工程提供了一个有价值的动物模型。     

SD大鼠间充质干细胞的分离培养及生物学特性研究

目的对SD大鼠不同组织的间充质干细胞（MSCs）进行分离培养并检测其生物学特性。方法分离SD大鼠骨髓、骨密质来源的MSCs，进行细胞表面抗原和细胞生长周期的鉴定。结果两种组织来源的细胞都呈成纤维细胞样，单个核，增殖能力强。细胞免疫组织化学结果显示，培养的细胞表达波形蛋白（vimention）、纤维连接蛋白（fibronectin）但不表达角蛋白（keratin）。细胞可传代10代以上并保持细胞表型。细胞周期显示90％以上细胞处于细胞静止期。结论分离、培养的两种组织的细胞均为MSCs，在体外培养条件下增殖能力强、表型稳定，可作为组织工程的种子细胞。     

异种关节软骨与MSCs体外共同培养的实验研究

目的提供一种新的种子细胞获得方法,解决软骨缺损修复过程中软骨数量不足的困难。方法人骨髓间充质干细胞体外扩增诱导分化后与兔的关节软骨细胞按不同比例共同培养利用real-time PCR技术分析细胞表型的表达情况。结果实验组2种细胞共培养4周后,混合培养显示正反馈调节软骨细胞的增殖,软骨细胞外基质、SOX9、Ⅱ型胶原基因表达增加,软骨细胞生成明显增加。结论间充质干细胞以旁分泌或自分泌的方式调节间充质干细胞向软骨细胞的转化。