MiR-615在平行培养的神经干细胞与运动神经元的表达比较

目的探讨MiR-615在脊髓源性神经干细胞与运动神经元间的表达特征。方法通过免疫磁珠法分离纯化胚胎大鼠脊髓运动神经元;通过神经克隆球形成技术分离纯化胚胎大鼠脊髓源性神经干细胞。采用TaqMan miR-615Assay定量检测培养的脊髓源性神经干细胞与运动神经元中miR-615的表达差异。结果通过平行培养技术分别获得了纯化的脊髓源性神经干细胞与运动神经元。定量检测结果显示,miR-615在分离的运动神经元中较在脊髓源性神经干细胞中显著高表达。结论本文提示miR-615可能在神经干细胞定向分化为运动神经元过程中发挥重要的调节作用。     

大鼠耳蜗雪旺细胞的体外培养和纯化

目的:探讨利用免疫磁珠从新生SD大鼠耳蜗螺旋神经节分离培养获得大量、高纯度雪旺细胞的方法。方法:选用1-3d SD大鼠,无菌条件下暴露双侧听泡,在高倍镜下仔细剥离蜗壳,开放耳蜗,完整取出耳蜗组织,分离并且除去膜蜗管外侧壁的血管纹和基底膜组织,然后剪碎。用0.25%的胰蛋白酶消化,用胎牛血清中止消化,离心以后加入DMEM/F12培养液培养。3-5天后对细胞应用免疫磁珠阳性分选方法进行纯化,培养2天后进行传代接种,培养过程中对提纯后的大鼠耳蜗雪旺细胞进行形态学观察、并绘制其生长曲线,采用细胞免疫荧光染色对细胞进行S-100免疫荧光鉴定并且计算细胞纯度。结果:分离培养后所得的细胞即为雪旺细胞;利用免疫磁珠阳性分选法对培养所得的细胞进行纯化,纯化后的大鼠耳蜗雪旺细胞纯度为97%±1.2%。结论:免疫磁珠法是一种有效的分离纯化新生大鼠仔鼠耳蜗螺旋神经节雪旺细胞的方法。所得耳蜗雪旺细胞活力强、纯度高,可以用于耳蜗雪旺细胞与螺旋神经节轴突的生长和再生等相关研究。     

心肌干细胞培养和纯化的实验方法研究

目的:探讨心肌干细胞(CSC)体外分离、培养和纯化方法,以建立重复性好、稳定性高的CSC培养的方法.方法:用不同的消化方法来分C57BL小鼠心脏组织中的细胞,将获得的细胞置于自行拟定的心肌干细胞培养液中培养.以c-kit、Sca-l和Sca-l/c-kit作为干细胞标记,用免疫磁珠法纯化细胞.用流式细胞仪、免疫荧光显微镜、激光共聚焦显微镜检测分选后所得细胞表面标记表达,并对比观察分选前后细胞生长情况,进一步了解CSC的生物学特性.结果:①从小鼠心肌组织中分离培养所得的细胞中,含有一种类似于文献报道中所提及CSC形态的细胞.②用免疫磁珠法可以分选出高纯度的CSC,实验中分选出CSC分别具有c-kit+-CD34-lin-、Sea-I+-CD34low-Lin-、Sea-1+c--kit+-CD34low-Lin-的表型.③分选后的干细胞经过1~2d的滞留期后,贴壁生长的细胞形态相对均一;而传代后细胞贴壁迅速,细胞形态多样.结论:从C57BL小鼠心脏中可以分离、培养获得CSC,并可用免疫磁珠法得以纯化.     

免疫磁珠纯化小鼠精原干细胞的研究

精原干细胞（spermatogonial stem cells,SSCs）富集纯化是利用SSCs进行基因修饰新方法等研究的前提基础。采用免疫磁珠分选法,使用干细胞抗体CD90.2进行小鼠SSCs的纯化富集,并采用流式细胞分析法和定量PCR验证了磁珠分选效率。流式细胞分析结果：免疫磁珠分选后SSCs纯度为50.11%。荧光定量PCR检测结果：磁珠分选后支持细胞特异表达基因 GATA4 显著下调（6倍）、SSCs表达基因 GFRα-1 上调（6.5倍）、生殖干细胞特异表达基因 OCT4 极显著上调（5.9倍）,3个基因相对表达量的变化说明,免疫磁珠分选效率为6倍。流式细胞分析法所产生的偏差可能是受到了未解离磁珠及SSCs本身转基因荧光的影响。     

免疫磁珠分选降低分化体系中胚胎干细胞的比例

研究目的:采用免疫磁珠分选系统（magnetic activated cell sorting, MACS）分离去除小鼠胚胎干细胞（murine embryonic stem cells, mES）向神经细胞分化时培养体系中的ES细胞,即对分化细胞进行纯化,以期减少移植致瘤性。方法：诱导mES细胞向神经细胞分化,取分化第四期的细胞,胰酶消化制成单细胞悬液,用mES特异性表面抗原SSEA-1（special stage embryonic antigen-1）单抗标记,间接免疫磁珠分选系统分离去除SSEA-1阳性细胞,流式细胞仪检测分选前后细胞中mES细胞的比例,台盼蓝染色检测分选前后细胞存活率。结果：经MACS分选后的阴性细胞中的SSEA-1阳性率可以由分选前的（7.19±1.36）%下降到（1.34±0.80）%,结果具有显著性差异;分选后的细胞存活率仍为92%左右,与分选前存活率无明显变化。结论 用SSEA-1作为表面标志,用MACS方法能有效地去除胚胎干细胞分化细胞中残存的胚胎干细胞,得到高纯度的分化细胞,并且细胞存活率不受影响,为下一步进行移植实验奠定基础。     

造血干细胞衰老体外模型构建及其生物学研究初探

造血干细胞（HSC）衰老与机体衰老密切相关。HSC衰老研究中的关键问题是HSC衰老模型的构建,迄今还未有公认的HSC衰老的体外模型,建立HSC衰老体外模型可为深入研究HSC衰老的生物学机理及调控机制奠定基础。本实验运用免疫磁珠分选法分离纯化小鼠Soft-1^＋ HSC,流式细胞术鉴定分选细胞的纯度达85％,免疫荧光示大量带绿色荧光Sca-1^＋细胞,     

重组人胶质细胞源性神经营养因子的生物学活性研究

从人星形胶质细胞瘤BT-325细胞中克隆胶质细胞源性神经营养因子(GDNF) cDNA序列.以大肠杆菌作为表达系统,GDNF蛋白在大肠杆菌JM103中获得了高效表达;表达产物经纯化、复性后,以8日龄鸡胚背根节（DRG）、14日龄胎鼠脊髓前角运动神经元以及新生大鼠大脑皮层胶质细胞作为实验材料,研究了GDNF的生物学活性,结果表明： rhGDNF可有效地促进DRG突起的生长,rhGDNF对体外培养的运动神经元表现出明显的促突起生长作用,并可显著提高体外培养运动神经元的存活率,rhGDNF 对体外培养的胶质细胞具有促增殖作用.     

两种精原干细胞高效能纯化方法的比较研究*

目的: 比较贴壁分离法和免疫磁珠法纯化小鼠精原干细胞(mSSCs) 的优缺点。方法: 分别选取10只12-15日龄的雄性C57BL/6小鼠,颈椎脱臼法处死,摘取睾丸用酶消化法获得曲细精管单细胞悬液,分别用贴壁分离法和免疫磁珠法从单细胞悬液中分离纯化mSSCs,并针对两种方法在细胞数量、分离效率以及对细胞增殖生长的影响等方面进行比较。结果: 两种纯化方法均可从小鼠曲细精管单细胞悬液中分离纯化得到干细胞,并可在体外培养后呈现出典型的精原干细胞特有的葡萄串状克隆,体外连续培养增殖超3个月。10只小鼠的睾丸经差异贴壁法纯化后可以得到3×10⁵±0.4×10⁵个mSSCs(n=5),细胞回收率(纯化后细胞数/曲细精管单细胞悬液细胞数)为1.5%±0.1%(n=5);经免疫磁珠法可以得到6×10⁵±0.4×10⁵个mSSCs(n=5),细胞回收率为3.0%±0.1%(n=5),免疫磁珠法得到的干细胞数量更高。差异贴壁法得到的干细胞更纯,因为体外培养5 d左右即得到干细胞集落,而免疫磁珠法得到的干细胞则约10 d才可以看到明显的细胞集落,但是两种纯化方法对细胞体外长期增殖生长没有明显的影响。结论: 两种方法均可以纯化得到高质量的mSSCs,,但两种方法各有优缺点。差异贴壁法较免疫磁珠法经济、实用,无需购买专门的设备和抗体磁珠,但获得的细胞数量相对较低,用时也较长。     

两种免疫磁珠分离法分选小鼠骨髓粒-单核祖细胞的效率比较

摘要 目的：提取小鼠骨髓细胞（bone marrow cell, BMC）,用两种不同的免疫磁珠分离（magnetic activated cell sorting, MACS）试剂盒从小鼠BMC中分选提纯粒-单核祖细胞（granulocyte-monocyte progenitor, GMP）,比较这两种免疫磁珠的分选效率。方法：从小鼠股骨和胫骨中提取BMC,通过两种不同的MACS试剂盒,即Lineage阳性细胞清除试剂盒和CD117阳性细胞分选试剂盒,分别得到Lineage-细胞群和CD117⁺细胞群,用代表GMP细胞表面标志物的荧光抗体标记,孵育后通过流式细胞荧光分选技术得到GMP细胞,并且对比得到GMP细胞的效率。结果：每2只野生型C57BL/6J小鼠可共收集骨髓细胞（7.02±1.24）×10⁷个,细胞活力为（91.86±5.24）%。经过Lineage阳性细胞清除试剂盒得到的细胞数量为（5.71±2.86）×10⁶个;经过CD117阳性细胞分选试剂盒得到的细胞数量为（2.70±0.56）×10⁶个。Lineage磁珠分选纯化得到的GMP细胞数占总细胞数的比例为（10.90±1.37）%,CD117磁珠分选纯化得到的GMP细胞数占总细胞数的比例为（4.83±2.08）%。结论：Lineage阳性细胞清除试剂盒能更有效分选小鼠骨髓细胞中的粒-单核祖细胞。     

一种手动解离、免疫磁珠分选加TIC培养液改良的小鼠原代海马小胶质细胞培养法

本文旨在研究手动解离、免疫磁珠分选加TIC培养液改良原代小胶质细胞的培养方法,获得高活性、高纯度且与在体状态更接近的小鼠海马原代小胶质细胞,以用于小胶质细胞的相关研究。选取2～4周龄SPF级C57BL/6J小鼠,PBS灌注后取海马组织剪碎,使用成年鼠脑组织解离试剂盒手动解离海马组织,获得单细胞悬液,再经去碎片试剂去除髓鞘等组织碎片。在4°C孵育CD11b免疫磁珠15 min后,细胞悬液经免疫磁珠细胞分选(magnetic activated cell sorting, MACS)两次过柱提高小胶质细胞纯度。将分选后细胞离心重悬,种在多聚赖氨酸包被后的24孔培养板中,用完全培养基或TIC培养液(以TGF-β、IL-34和胆固醇为主要营养成分的无血清培养基)培养4 d后进行其他检测。结果显示:(1)使用成年鼠脑组织解离试剂盒手动解离可得到含有(56.03±2.10)%活细胞的单细胞悬液;(2)与免疫抗体包被筛选法(immunopanning)相比,经过MACS两步分选后,可得到更多且纯度高达(86.20±0.68)%的小胶质细胞;(3)使用TIC培养液培养4 d后,可获得分枝状、形态类似静息状态的原代小胶质细胞;(4) q RT-PCR检测显示,与完全培养基培养相比,TIC培养液培养的小胶质细胞在4 d和7 d后TNF-α、IL-1β及CCL2 m RNA表达水平更接近急性分离后的小胶质细胞。上述结果提示,采用手动解离海马组织,经MACS两步分选及TIC培养后,可以获得高纯度、高活性且接近在体静息状态的小胶质细胞。     

人工合成树状串联hTERT表位肽对mDC表型和功能的影响

目的 通过对树状串联hTERT表位肽（MAP）与无肽刺激组髓样树突状细胞（mDC）的相关检测,研究MAP肽对mDC的表型和功能的影响.方法 人工固相合成四分支的MAP肽,免疫磁珠分选mDC,流式细胞技术检测相关表面分子.ElISA分别检测两组mDC培养基的IL-12p70含量,并作统计学分析.结果 人工合成MAP肽纯度高（95.26 %）,免疫磁珠分选mDC纯度为72.59 %,相比于无肽刺激组mDC,MAP肽刺激组成熟（培养第9天）时MHCⅡ类分子为83.90 %、MHCⅠ类分子为91.08 %,CD86：77.03 %,CD83：92.16 %;IL-12p70的含量也大于无肽刺激组,且有统计学差异.结论 人工合成hTERT的MAP肽能足够强的激活mDC,刺激其成熟和功能的表达,可作为mDC抗肿瘤疫苗的刺激肽结构.     

Development of substance P receptors on rat motoneurons in vitro.

Experiments were performed to examine the influence of interneuronal interactions on the expression of neurotransmitter receptors by developing mammalian CNS neurons. Receptors for the neuropeptide, substance P (SP), were assayed on embryonic rat motoneurons and other spinal cord neurons developing in vitro by the binding of 125I-SP to live neurons. Scatchard analysis showed the presence of high-affinity binding sites, and binding competition assays using SP, neurokinin A, or neurokinin B indicated that the high-affinity 125I-SP binding sites on these neurons were type NK1 tachykinin receptors, or SP receptors (SPRs). Neurons in the spinal cords of rats at Embryonic Day 14 displayed no SPRs. Cell-surface SPRs were detected on spinal cord neurons within 24 hr after they were placed in culture, however, and the level of 125I-SP binding increased for several days. SPRs were assayed on spinal motoneurons that had been identified by retrograde labeling with a fluorescent tracer, isolated in high purity by fluorescence-activated cell sorting (FACS), and maintained in culture. Motoneurons grown in isolation from other neurons developed SPRs in vitro along the same time course as neurons in heterogeneous spinal cord cultures. These results show that rat spinal motoneurons can express SPRs early in their development, and they suggest that the initial expression of SPRs by developing motoneurons does not require interaction with other neurons.     

Motoneurons purified by cell sorting respond to two distinct activities in myotube-conditioned medium

Spinal motoneurons from chick embryos were purified by retrograde transport and fluorescence-activated cell sorting. Growth conditions for motoneurons were studied, with experiments focused on the effects of conditioned media from chick myotubes, fibroblasts, and spinal cord dividing cells. Motoneurons rapidly extended neurites when plated onto polylysine-coated dishes that had been exposed to these conditioned media. Enzymatic analysis of the substratum-binding, neurite outgrowth-promoting activity from myotube-conditioned medium indicated that it contained heparan sulfate and protein. The neurite outgrowth-promoting activity sedimented as a peak centered at a density of 1.34 in associative cesium chloride gradients, and eluted near the void volume of a Sepharose CL-6B column. Inclusion of myotube conditioned medium in the culture medium of motoneurons also enhanced their survival over periods greater than 2 days in culture. This enhancement of survival could not be explained by myotube-conditioned medium providing motoneurons with a continuous supply of the neurite outgrowth-promoting activity. Media conditioned by spinal cord dividing cells and fibroblasts supported motoneuron survival to some extent, but this effect was not as great as that of myotube-conditioned medium.     

Isolation of neural crest-derived stem cells from rat embryonic mandibular processes

BACKGROUND INFORMATION: Substantial evidence indicates the existence of NCSCs (neural crest-derived stem cells) in embryonic mandibular processes; however, they have not been fully investigated or isolated. The aim of the present study was to isolate stem cells from mandibular process during embryonic development by MACS (magnetic-activated cell sorting). The findings show that the cells are multipotent and self-renewing. RESULTS: LNGFR (low-affinity nerve-growth-factor receptor)+ cells were isolated from rat embryonic mandibular processes by MACS. The cells were grown in clonal culture by limiting dilution to assess their developmental potential. Clone analysis indicated that, first, LNGFR+ cells are multipotent, being able to generate at least neurons and Schwann cells, similar to peripheral neural crest stem cells. Secondly, multipotent LNGFR+ cells generate multipotent progenies, indicating that they are capable of self-renewal and therefore are stem cells. Thirdly, manipulation of the medium supplementation alters the fate of the isolated LNGFR+ cells. CONCLUSIONS: These results indicate that LNGFR antibodies label NCSCs with high specificity and purity, and suggest that positive selection using these antibodies may become the method of choice for obtaining multipotent cells from rat embryonic mandibular processes for tissue engineering or regenerative therapeutic use.     

利用IL－3／GM－CSF融合蛋白（PIXY－321）扩增脐血造血细胞方法的初步建立

利用单克隆抗体免疫磁珠吸附方法分离脐血ＣＤ３４＋细胞,并观察了ＩＬ３／ＧＭＣＳＦ融合蛋白（ＰＩＸＹ３２１）对脐血ＣＤ３４＋细胞的刺激作用。ＰＩＸＹ３２１对脐血ＣＤ３４＋细胞扩增作用大于ＩＬ３和ＧＭＣＳＦ单独及联合应用。在液体培养条件下,每毫升２０ｎｇＰＩＸＹ３２１可有效地扩增脐血造血祖细胞,适宜扩增时间为５－８天,扩增后造血祖细胞的数量可达扩增前的８－１０倍,从而初步建立了一种简单可行的脐血造血细胞扩增方法。     

Enrichment of transplantable germ cells in salmonids using a novel monoclonal antibody by magnetic‐activated cell sorting

In the fish germ cell transplantation system, only type A spermatogonia (ASGs) and oogonia are known to be incorporated into the recipient genital ridges, where they undergo gametogenesis. Therefore, high colonization efficiency can be achieved by enriching undifferentiated germ cells out of whole testicular cells. In this study, we used magnetic‐activated cell sorting (MACS) for enriching undifferentiated germ cells of rainbow trout using a monoclonal antibody that recognizes a specific antigen located on the germ cell membrane. We screened the antibodies to be used for MACS by performing immunohistochemistry on rainbow trout gonads. Two antibodies, nos. 172 and 189, showed strong signals for ASGs and oogonia. Next, we performed MACS with antibody no. 172 using gonadal cells isolated from vasa‐gfp rainbow trout showing GFP in undifferentiated germ cells. We found that GFP‐positive cells are highly enriched in antibody no. 172‐positive fractions. Finally, to examine the transplantability of MACS‐enriched cells, we intraperitoneally transplanted sorted or unsorted cells into recipient larvae. We observed that transplantability of sorted cells, particularly ovarian cells, were significantly higher than that of unsorted cells. Therefore, MACS with antibody no. 172 could enrich ASGs and oogonia and become a powerful tool to improve transplantation efficiency in salmonids.     

甘草酸二铵对于HCV相关性B-NHLCD25-和CD25+T细胞增殖影响研究

目的:本研究初步探究甘草酸二铵(Diammonium Glycyrrihizinate,DG)对HCV相关性B细胞非霍奇金淋巴瘤(B-cellnon-Hodgkin's lymphoma,B-NHL)CD25-T细胞、CD25+T细胞的免疫调控作用。方法:应用流式细胞分析仪检测HCV相关性B-NHL CD4+CD25+T细胞占CD4+T细胞的比例、CD25+细胞占总PBMC比例,并与单纯HCV感染患者、健康人检测结果相对照。应用免疫磁珠分离法(MACS)分选获得CD25-和CD25+细胞,将两者和未分选的外周血单个核细胞(peripheral blood mononuclearcell,PBMC)以CFSE标染孵育72小时后,应用流式细胞分析仪将APC CD3阳性细胞设定为门检测CD25-T细胞、未分选T细胞、CD25+T细胞的增殖情况,及甘草酸二铵干预后的CD25-T细胞、CD25+T细胞增殖情况。结果:应用流式细胞分析仪检测健康人、单纯HCV感染者和HCV相关性B-NHL患者在CD4+CD25+占总CD4+细胞比例和CD25+占总细胞比例上均呈现逐步递增的关系(分别为33.94%±2.18%,57.95%...     

鸡脊髓运动神经元中钙离子通道α2亚基和钠离子通道α亚基的免疫学表达

目的观察电压门控钙离子通道α2（votage—gated calcium channel,VGCC）亚基和电压门控钠离子通道α（voltage—gated sodium channel,VGSC）亚基在鸡脊髓运动神经元中的表达,并探讨相互表达的关系。方法应用免疫组织化学（ABC法）观察鸡脊髓前角神经元中cCα2亚基和sCα亚基的表达,并应用免疫荧光双标记法观察鸡脊髓运动神经元中CCα2亚基和SCα亚基表达的关系。结果CCα2亚基主要表达于脊髓IX层的大型神经元中,Ⅷ层的部分小型神经元亦呈CCα2亚基免疫阳性,大约83％的脊髓运动神经元呈CCα2阳性。CCα2亚基免疫反应物位于神经元胞浆和近位树突中。SCα亚基免疫反应物主要表达于脊髓运动神经元细胞核中,或同时表达在神经元的细胞核及胞浆中。一些有髓轴突和神经元近位树突亦呈SCα亚基免疫强阳性。大约46％的运动神经元呈SCα亚基阳性,并所有SCα亚基免疫阳性运动神经元均为CCα2亚基阳性。结论脊髓运动神经元中CCα2亚基和SCα亚基有多样性表达,可能表明运动神经元的不同运动活性。     

甘草酸二铵对于HCV相关性B—NHLCD25-和CD25＋T细胞增殖影响研究

目的：本研究初步探究甘草酸二铵（Diammonium Glycyrrihizinate,DG）对HCV相关性B细胞非霍奇金淋巴瘤（B-cellnon-Hodgkin-Slymphoma,B-NHL）CD25-T细胞、CD25＋T细胞的免疫调控作用。方法：应用流式细胞分析仪检测HCV相关性B-NHLCD4＋CD25＋T细胞占CD4＋1r细胞的比例、CD25＋细胞占总PBMC比例,并与单纯HcV感染患者、健康人检测结果相对照。应用免疫磁珠分离法（MACS）分选获得CD25-和CD25＋细胞,将两者和未分选的外周血单个核细胞（peripheralblood mononuclear cell。PBMC）以CFSE标染孵育72小时后,应用流式细胞分析仪将APCCD3阳性细胞设定为门检测CD25T细胞、未分选T细胞、CD25＋T细胞的增殖情况,及甘草酸二铵干预后的CD25-T细胞、CD25＋T细胞增殖情况。结果：应用流式细胞分析仪检测健康人、单纯HCV感染者和HCV相关性B—NHL患者在CD4＋CD25＋占总CD4＋细胞比例和CD25＋占总细胞比例上均呈现逐步递增的关系（分别为33．94％±2．18％,57．95％±1．77％,70．24％±12．75％,P〈0．05;18．16％±2．23％,33．45％±1132％,54.69％±8．66％,P〈0．05）。CFSE标染后孵育72小时检测（MI＋M2）分裂相百分比呈现CD25-T细胞最高、未分选T细胞其次、CD2YT细胞最低的表现（分别为74．4％±1．2％,63．1％±5．4％,47．2％±5．9％,P〈0．05）。甘草酸二铵干预后CD25-T细胞较未干预CD25T细胞M1分裂相百分比增加（分别为57．7％±4．2％,46．5％±5．6％,P〈0．05）。甘草酸二铵干预后CD25＋T细胞较未干预cD25＋1r细胞M1分裂相百分比减少（分别为14．7％±1．3％,22．1％±4．1％,P〈0．05）。结论：HCV相关性B-NHLCIM＋CD25＋、CD25＋细胞百分比较单纯HCV感染者、健康人明显增加,提示存在T细胞免疫抑制,且抑制程度重于单纯HCV感染。去除CD25＋细胞后CD25T细胞增殖较未去除CD25＋的T细胞增殖活跃,说明HCV相关性B-NHL患者的CD25＋细胞能够抑制CD25-T细胞增殖。而DG干预后HCV相关性B-NHLCD25＋T细胞增殖M1分裂相减少,而CD25T细胞增殖M1分裂相增加,表明DG对HCV相关性B-NHL具有抑制CD25＋T细胞增殖而促进CD25-T细胞增殖的积极免疫调节作用。     

Isolation and characterization of the CD133+ precursors from the ventricular zone of human fetal brain by magnetic affinity cell sorting

A fast and effective method to enrich large number of neural precursors from the ventricular zone of human fetus by magnetic affinity cell sorting (MACS) is reported. After incubation with phycoerythrin (PE)-conjugated anti-CD133 antibodies and anti-PE magnetic beads followed by one cycle of MACS, CD133(+) cells were harvested at 85% purity as confirmed by flow-cytometry and immunocytochemistry. In contrast to CD133(-) cells, these CD133(+) cells initiated primary and secondary neurospheres in culture, and the progeny of sorted cells could be differentiated into both neurons and glia, indicating that these highly enriched cells are capable of self-renewal and multi-lineage potential.