兔骨髓基质细胞Feridex标记及体外MRI成像的实验研究

目的使用超顺磁性氧化铁菲立磁（FE）和转染试剂多聚赖氨酸（PLL）对骨髓基质细胞（BMSCs）进行体外标记．并在体外对标记细胞进行MRI示踪，确定其标记BMSCs的适宜浓度。方法使用不同浓度（10、25、50、75μg／mL）的FE复合PLL，形成FE-PLL并标记新西兰大白兔BMSCs后，分为5组（A：纯BMSCs组；B：5μg／mLFE＋0．75μg／mLPLL组；C：12．5μg／mLFE＋0．75μg／mLPLL组；D：25μg／mLFE＋0．75μg／mLPLL组；E：37．5μg／mLFE＋0．75μg／mLPLL组）。对各组细胞分别进行普鲁士蓝染色、流式细胞仪检测、透射电镜观察．检测FE-PLL标记兔BMSCs的效率及其对凋亡的影响。体外扫描采用4．7TMR机，扫描序列为轴面T2WI。结果FE可以高效率标记BMSCs，被标记的细胞显微镜下呈淡黄或深黄，颜色的深浅与所加FE的剂量呈正相关；胞质内散在分布许多含膜的囊泡样包涵体结构．囊泡内有浓聚细小的铁颗粒．从B组～E组依次增多。流式细胞仪结果显示，5、12．5、25μg／mL各组FE对细胞无不良影响，而37．5μg／mL组凋亡细胞明显增加。体外4．7TMRI显示未标记组无信号改变，呈显著高信号．标记组随FE浓度的增高信号改变增大，信号降低的越明显。结论FE可以用来体外标记兔BMSCs．在适宜浓度下对其生物学活性无明显影响。并能在MRI下达到示踪的目的。     

大鼠脂肪干细胞磁性标记及MRI成像研究

目的探索菲立磁和转染试剂体外磁性标记大鼠脂肪干细胞（ADSCs）的可行性。方法从成年大鼠脂肪组织中分离获取ADSCs进行培养传代，用Feridex-多聚左旋赖氨酸（FE—PLL）复合物标记ADSCs，普鲁士兰染色和台盼蓝排除实验等方法鉴定“FE—PLL”标记的ADSCs的效率和细胞活力。同时对“FE—PLL”标记的ADSCs行体内外MRI成像。结果普鲁士蓝染色显示“FE—PLL”标记的ADSCs胞质内出现细小的蓝色铁颗粒，标记率100％。标记ADSCs24h及1、2、3w的台盼蓝拒染率与未标记ADSCs相比较差异无统计学意义（P〉0．05）。体外MRI显示磁标记的ADSCs在T2WI上可使信号明显降低，采用T2WI和T2^＊WI对经立体定向仪移植的标记ADSCs进行活体示踪，二者均可显示MR信号降低，以T2^＊WI最敏感。结论应用Feridex（FE—PLL）复合物标记ADSCs安全、有效；MRI可在活体下无创性示踪ADSCs。     

菲立磁标记大鼠骨髓基质细胞及自体移植后磁共振示踪的研究

目的初步探索利用菲立磁(Feridex)和转染试剂体外磁性标记大鼠骨髓基质细胞这一方法的可行性，为将来临床上应用磁共振成像(MRI)追踪标记细胞奠定基础。方法无菌条件下行股骨取骨髓，梯度密度离心法分离获取大鼠骨髓基质细胞，使用“Feridex-多聚赖氨酸复合物(FE-PLL)”标记骨髓基质细胞，采用普鲁士蓝染色、电镜和台盼蓝排除实验等方法鉴定FE-PLL标记大鼠骨髓基质细胞的效率和细胞的活力，并对FE-PLL标记骨髓基质细胞的增殖和分化能力进行评估。将FE-PLL标记和未标记后的骨髓基质细胞分别移植人大鼠左有侧尾壳核脑内．细胞移植后1、4、7周应用MRI对脑内移植的细胞进行活体示踪，最后利用组织切片进行普鲁士蓝染色。结果菲立磁可以高效率地标记骨髓基质细胞，标记效率在99%左右。普鲁士蓝染色显示FE-PLL标记骨髓基质细胞胞质内出现细小的蓝色铁颗粒。电镜结果显示FE-PLL标记的骨髓基质细胞胞质内含有许多包裹铁颗粒的囊泡。与正常未标记的细胞相比较，FE-PLL标记对骨髓基质细胞的活力、增殖和分化等能力没有明显的影像。MRI检查发现脑内移植的标记细胞在磁共振上呈明显的低信号改变，未标记细胞侧脑组织无明显的低信号改变，与组织学切片结果基本相一致。结论以上结果提示菲立磁可以用来体外标记骨髓基质细胞，利用MRI技术可以对脑内移植后的标记细胞进行初步的活体追踪。     

菲立磁标记兔BMSCs自体移植脊髓后的核磁共振活体示踪及形态学研究

目的通过观察菲立磁标记兔骨髓源性神经干细胞(BMSCs)自体移植脊髓后的核磁共振活体示踪及形态,期待找到一种应用非侵袭性方法来识别、跟踪BMSCs的存活状态及与宿主组织整合情况的方法。方法无菌条件下股骨取骨髓,梯度密度离心法分离获取兔骨髓基质细胞;使用“Feridex-多聚赖氨酸复合物(FE-PLL)”标记骨髓基质细胞,采用普鲁士兰染色和台盼蓝排除实验等方法鉴定FE-PLL标记兔骨髓基质细胞的效率和细胞的活力;体外标记的细胞自体脊髓移植,磁共振、免疫组织化学染色和透射电镜检查。结果普鲁士蓝染色显示FE-PLL标记骨髓基质细胞胞质内出现细小的蓝色铁颗粒;与正常未标记的细胞相比较,FE-PLL标记对骨髓基质细胞的活力、增殖和分化等能力没有明显的影响;经菲立磁标记的兔BMSCs自体脊髓移植后,可在核磁共振上活体示踪。结论菲立磁与核磁共振联合可无创性活体标记检测移植的神经干细胞基本的存在部位、存在方式及其一些生物学特性,可以用来活体示踪移植的BMSCs。     

甲基强的松龙对伽玛刀照射后胶质细胞Cx43和GFAP表达的影响

目的 研究甲基强的松龙（MP）对伽玛刀照射后胶质细胞缝隙连接蛋白43（Cx43）和胶质纤维酸蛋白（GFAP）表达的影响。方法体外培养原代星形胶质细胞,经伽玛刀照射（边缘剂量32Gy）并培养36h后随机分为1μg／ml、5μg／ml、10μg／ml、20μg／ml、30μg／ml、40μg/ml组及实验对照组,各组进一步随机分为48h、72h、96h、120h4个亚组。将各组胶质细胞与相应剂量MP共培养,于48、72、96、120h各时间点采用免疫组化方法检测GFAP及Cx43的表达。结果伽玛刀照射后,胶质细胞Cx43表达降低,GFAp表达增高。添加MP后,20μg／ml、30μg／ml组Cx43呈时间依赖性上调;GFAP表达虽呈时间依赖性上升,但其峰值低于实验对照组,峰值出现时间亦晚于实验对照组。结论MP可上凋伽玛刀照射后胶质细胞Cx43的表达,抑制GFAP表达的上升趋势。     

超小超顺磁氧化铁颗粒标记对脂肪源间充质干细胞生物学特性的影响

目的 使用超小超顺磁氧化铁颗粒(USPIO)对大鼠脂肪源间充质干细胞(ADSCs)进行体外标记,研究不同浓度的USPIO对大鼠ADSCs生物学活性的影响,确定其标记ADSCs的适宜浓度. 方法 实验分为8个组,其中6组依次添加不同终浓度的USPIO(180 μg/mL、135 μg/mL、90 μg/mL、45 μg/mL、22.5 μg/mL、11.25μg/mL),另2组为阴性转染组和空白对照组.普鲁士蓝染色检测USPIO标记ADSCs的效率,同时采用CCK-8及Alamar blue法检测各组细胞增殖情况. 结果 USPIO标记浓度在45 μg/mL时,普鲁士蓝染色后ADSCs胞浆内可见大量蓝色颗粒,标记效率在95％以上；USPIO标记浓度在90 μg/mL及以上时,标记效率约100％.CCK-8及Alamar blue检测结果表明USPIO在11.25～90 μg/mL范围内对细胞活力的影响较小且差异无统计学意义(P＞0.05),故可将45-90 μg/mL确定为适宜浓度. 结论 USPIO可在体外有效标记ADSCs,并且在适宜浓度范围内对细胞生物学活性无明显影响.     

游离血红蛋白对体外培养成年大鼠嗅鞘细胞存活的影响

目的观察不同浓度游离血红蛋白（FHb）对体外培养大鼠嗅鞘细胞（OECs）存活的影响。方法采用成年大鼠（2．5月）嗅球培养OECs，培养第8天用S-100免疫组化鉴定纯度后，将培养的OECs根据加入的FHb浓度分为1，10，50，100μmol／L组及正常对照组，观察不同浓度FHb下OECs形态学变化；培养24h后采用MTT实验检测不同浓度FHb组细胞活力；并用碘化丙啶（PI）和Hocchst33342荧光双染色观察检测细胞死亡。结果大鼠OECs纯度为（72±6）％；MTT试验显示各组细胞活力随血红蛋白浓度的升高而降低；PI／Hoechst33342双荧光染色显示在对照组未见PI染色阳性细胞，各FHb组细胞PI／Hoechst33342比例随血红蛋白浓度增加而升高。结论FHb对OECs有毒性作用且随浓度的增加而增加。     

Sinerem标记大鼠骨髓基质细胞及移植后活体示踪研究

目的初步探索利用欣诺（Sinerem）和转染试剂体外磁性标记大鼠骨髓基质细胞这一方法的可行性,为将来临床上应用MRI追踪标记细胞奠定基础。方法无菌条件下行股骨取骨髓,梯度密度离心法分离获取大鼠骨髓基质细胞,使用Sinerem-多聚赖氨酸复合物（SE—PLL）标记骨髓基质细胞,采用普鲁士兰染色、电镜和台盼蓝排除实验等方法鉴定SE—PLL标记大鼠骨髓基质细胞的效率和细胞的活力,并对SE—PLL标记骨髓基质细胞的增殖和分化能力进行评估。将SE—PLL标记和未标记后的骨髓基质细胞分别移植入大鼠左右侧尾壳核脑内,细胞移植后1、4、7w应用MRI对脑内移植的细胞进行活体示踪,最后利用组织切片进行普鲁士兰染色。结果Sinerem可以高效率地标记骨髓基质细胞,标记效率在99％左右。普鲁士蓝染色显示SE—PLL标记骨髓基质细胞胞质内出现细小的蓝色铁颗粒。电镜结果显示sE—PLL标记的骨髓基质细胞胞质内含有许多包裹铁颗粒的囊泡。与正常未标记的细胞相比较,SE—PLL标记对骨髓基质细胞的活力、增殖和分化等能力没有明显的影响。MRI检查发现脑内移植的标记细胞在磁共振上呈明显的低信号改变,未标记细胞侧脑组织无明显的低信号改变,与组织学切片结果基本一致。结论以上结果提示Sinerem可以用来体外标记骨髓基质细胞,利用MRI技术可以对脑内移植后的标记细胞进行初步的活体追踪。     

Resovist标记神经干细胞向大鼠局灶性脑缺血区域的迁移：MRI体内追踪

摘要 背景：Resovist是一种超顺磁性氧化铁,能够标记神经干细胞。本实验成功制备Resovist标记的神经干细胞（磁标记神经干细胞）,并利用MRI技术活体内追踪磁标记神经干细胞向大鼠脑部缺血区的迁移。 目的：利用核磁共振技术（MRI）活体追踪Resovist标记的神经干细胞移植治疗大鼠局灶性脑缺血。 设计,时间,地点：体外进行细胞学研究及大鼠脑内活体追踪试验。实验从2006年12月到2009年2月在哈尔滨医科大学基础实验室及哈尔滨医科大学附属第二医院神经科和MRI室完成。 材料：哈尔滨医科大学动物中心提供的新生清洁级SD大鼠 方法：神经干细胞培养、传代;制备Resovist标记的神经干细胞;利用免疫细胞化学、透射电镜和Prussian blue 染色等方法对Resovist标记神经干细胞的生长曲线进行研究。核磁共振追踪活体磁标记神经干细胞。 主要观察指标：免疫细胞化学、透射电镜、普鲁士蓝染色和MRI等方法 结果：在原代及传代细胞中有Nestin阳性细胞即神经干细胞。Resovist与神经干细胞共同孵育后,透射电镜及Prussian blue 染色显示胞浆中含有铁颗粒,铁颗粒也可以随细胞的分裂增殖而传到子代细胞中。随Resovist浓度的增高(2.8－11.2μg/ml), Resovist对神经干细胞存活无显著性影响。当Resovist的浓度大于22.4μg/ml时,影响其存活。活体状态下,MRI成功追踪到Resovist标记神经干细胞(Resovist浓度为 11.2μg/ml)呈低信号,并随时间推移,细胞向缺血灶迁移。 结论：本实验利用Resovist作为磁标记探针,成功制备磁标记神经干细胞。利用核磁共振（MRI）技术对磁标记神经干细胞进行活体追踪,观察细胞移植后的存活、迁移状况。     

1101/神经干细胞超顺磁性氧化铁标记及对体外诱导分化的影响

目的 研究超顺磁性氧化铁（Superparam agnetic iron oxide）体外标记人神经干细胞的效果,为将来临床上应用磁共振成像（MRI）追踪标记细胞奠定基础。 方法 取孕13周人胚胎脑组织,制备成单细胞悬液,用添加表皮生长因子（EGF,20ng/ml）和碱性成纤维细胞生长因子（bFGF,20ng/ml）的体外培养人神经干细胞球,并做传代及诱导分化。利用Feridex标记分散成单细胞的神经干细胞,行普鲁士蓝染色检测标记阳性率,5%胎牛血清（FBS）诱导标记后的神经干细胞分化,并用免疫荧光染色检测分化细胞。 结果 培养一周即可见大量的神经干细胞球,Feridex标记神经干细胞行铁染色显示胞浆中含有铁颗粒,Feridex标记的神经干细胞阳性率达90%。标记后的神经干细胞经5% FBS诱导分化能够分化为神经元和星形胶质细胞 。 结论 Feridex 能够标记神经干细胞,标记不影响神经干细胞的生物学特性,标记后能够正常体外扩增培养和定向诱导分化,本研究为神经干细胞临床移植追踪提供了新的方法。     

Distribution of monoamine-synthesizing neurons in the human medulla oblongata

We have employed immunohistochemical and morphometric procedures to study the distribution of monoamine-synthesizing neurons in the medulla oblongata of the adult human, utilizing antibodies to tyrosine hydroxylase (TH), phenylethanolamine N-methyltransferase (PNMT), and phenylalanine hydroxylase (PH8). In the human brain, the antigen with which PH8 reacts occurs within neurons that presumably synthesize serotonin (Haan et al., '87). Neurons containing these antigens were mapped and counted in successive coronal sections with the aid of a computer-assisted procedure. The results indicate that monoamine-synthesizing neurons are distributed in the human brain in patterns broadly similar to those described for other species. TH-immunoreactive cells extended caudorostrally for approximately 32 mm commencing at the spinomedullary junction and ending 8 mm caudal to the pontomedullary junction. In coronal sections these TH-immunoreactive neurons were seen in the lateral medulla dorsal to the inferior olive extending in a continuous band to the dorsomedial medulla. Above the obex the majority of these cells apparently synthesize adrenaline since many PNMT-immunoreactive cells were also found in this region. There were few or no PNMT-immunoreactive cells caudal to the obex, indicating that the TH-immunoreactive cells in this region synthesize either noradrenaline or dopamine. Approximately 65% of these TH-immunoreactive neurons contained melanin pigment, whereas few or no PNMT-immunoreactive cells contained melanin pigment. PH8-immunoreactive cells extended throughout the rostrocaudal extent of the medulla oblongata (approximately 40 mm). In coronal sections the majority were found in the medullary raphe nuclei. However, many cells throughout the rostrocaudal extent of the medulla were found laterally intermingled with catecholamine-synthesizing neurons. Occasional neurons in the lateral medulla appeared to contain both PH8- and TH-immunoreactivity.     

Immunocytochemical localization of three vesicular glutamate transporters in the cat retina

Vesicular transporters play an essential role in the packaging of glutamate for synaptic release and so are of particular importance in the retina, where glutamate serves as the neurotransmitter for photoreceptors, bipolar cells, and ganglion cells. In the present study, we have examined the distribution of the three known isoforms of vesicular glutamate transporter (VGLUT) in the cat retina. VGLUT1 was localized to all photoreceptor and bipolar cells, whereas VGLUT2 was found in ganglion cells. This basic pattern of complementary distribution for the two transporters among known populations of glutamatergic cells is similar to previous findings in the brain and spinal cord. However, the axon terminals of S-cone photoreceptors were found to express both VGLUT1 and VGLUT2 and some ganglion cells labeled for both VGLUT2 and VGLUT3. Such colocalizations suggest the existence of dual modes of regulation of vesicular glutamate transport in these neurons. Staining for VGLUT2 was also present in a small number of varicose processes, which were seen to ramify throughout the inner plexiform layer. These fibers may represent axon collaterals of ganglion cells. The most prominent site of VGLUT3 immunoreactivity was in a population of amacrine cells; the axon terminals of B-type horizontal cells were also labeled at their contacts with rod spherules. The presence of the VGLUT3 transporter at sites not otherwise implicated in glutamate release may indicate novel modes of glutamate signaling or additional roles for the transporter molecule.     

血管组织工程种子细胞在再生医学中的应用*☆◇

背景：小口径人工血管替代人体小动脉和静脉一直未获得满意的效果，因此研制出一种拥有较高远期通畅率的小口径人工血管成为了一个重要的研究课题。 目的：综述种子细胞在血管组织工程的研究进展。 方法：以 “Vascular tissue engineering, Seeding cells”为检索词，应用计算机检索Pubmed 数据库1960/2009有关文章。纳入有关血管组织工程种子细胞的文献。排除原始文献设计方法简单、结果可靠性差、非英文文献及结果重复的文献，保留35篇文献做进一步分析。 结果与结论：内皮细胞和平滑肌细胞是目前常用的种子细胞。内皮细胞和平滑肌细胞共同培养的体系，模拟体内环境，保持内皮细胞和平滑肌细胞具有正常的分泌功能和表型。骨髓间充质细胞可被有效的分离和扩增，在特定培养条件下可以诱导分化为多种血管细胞。在再生医学和生物组织工程方面有强大的潜力。     

Cellular and subcellular distribution of NMDA receptor subunit NR2B in the retina

Immunocytochemical studies showed the presence of staining for the N-methyl-D-aspartate (NMDA)-R2B glutamate receptor subunit at multiple sites in the cat retina. Reaction product in photoreceptor cells was localized at the inner/outer segment junction and in the axon terminals. Staining within the inner retina was limited to ganglion cells and their dendrites ramifying throughout the inner plexiform layer. These cells were seen to receive synaptic input from cone bipolar cells in both sublaminae. As with other glutamate receptor subunits, this immunoreactivity was typically confined to a single postsynaptic element at a cone bipolar dyad complex. Immunocytochemical localization of the NMDA-R1 subunit, considered to be an essential component of functional receptors, showed a widespread distribution across the retina including all the sites where NMDA-R2B staining was seen. Immunoprecipitation and Western blot analysis were used to confirm the presence of the NR2B receptor protein and its association with the NR1 subunit in both proximal and distal retinal layers. The findings suggest that NMDA-R2B subunits are positioned for multiple functions within the retina.     

周围神经组织工程中种子细胞的最新研究进展

典型的组织工程化人工神经主要包括种子细胞、支架材料以及有助于细胞生长、分化的细胞外基质，其中数量足够、不引起免疫排斥且有再生活力的种子细胞是其前提和基础。目前常用的种子细胞有雪旺氏细胞（SCs）、嗅球成鞘细胞（OECs）、骨髓基质细胞（BMSCs）和神经干细胞（NSCs）等。SCs一直是周围神经损伤修复研究领域的热点，OECs、BMSCs和NSCs修复周同神经损伤也在起步中。本从组织工程方面就上述四种细胞的最新研究进展进行综述，同时就存在的问题进行讨论。[第一段]     

Differential regulation of ciliary neurotrophic factor receptor-α expression in all major neuronal cell classes during development of the chick retina

Ciliary neurotrophic factor (CNTF) exerts a multiplicity of effects on a broad spectrum of target cells, including retinal neurons. To investigate how this functional complexity relates to the regulation of CNTF receptor α (CNTFRα) expression, we have studied the developmental expression of the receptor protein in chick retina by using immunocytochemistry. During the course of development, the receptor is expressed in all retinal layers, but three levels of specificity can be observed. First, the expression is regulated temporally with immunoreactivity observed in ganglion cells (embryonic day 8 [E8] to adult), photoreceptor precursors (E8–E12), amacrine cells (E10 to adult), bipolar cells (E12–E18), differentiated rods (E18 to adult), and horizontal cells (adult). Second, expression is restricted to distinct subpopulations of principal retinal neurons: preferentially, large ganglion cells; subpopulations of amacrine cells, including a particular type of cholinergic neuron; a distinctly located type of bipolar cell; and rod photoreceptors. Third, expression exhibits subcellular restriction: it is confined largely to dendrites in mature amacrine cells and is restricted entirely to outer segments in mature rods. These data correlate with CNTF effects on the survival of ganglion cells and mature photoreceptors, the in vitro differentiation of photoreceptor precursors and cholinergic amacrine cells, and the number of bipolar cells in culture described here or in previous studies. Thus, our results demonstrate an exceptional degree of complexity with respect to the regulation of neuronal CNTFRα expression in a defined model system. This suggests that the same signaling pathway is used to mediate a variety of regulatory influences, depending on the developmental stage and cell type. J. Comp. Neurol. 400:244–254, 1998. © 1998 Wiley-Liss, Inc.     

Distribution of neuropeptidelike immunoreactivities in the guinea pig olfactory bulb

The distribution of neuropeptidelike immunoreactivities in the adult guinea pig olfactory bulb was studied immunohistochemically with antisera raised against neurotensin (NT), substance P (SP), methionine-enkephalin-Arg6-Gly7-Leu8 (ENK), somatostatin (SOM), neuropeptide Y (NPY), and cholecystokinin-8 (CCK). In the main olfactory bulb, NT-like immunoreactive (NT-IR) neurons were found among periglomerular cells. In addition, a few periglomerular cells showed ENK-like immunoreactivity. Granule cells displaying SP- or ENK-like immunoreactivities and short axon cells with SOM- or NPY-like immunoreactivities were observed in the deeper half of the granule cell layer. SOM-IR short axon cells were also seen in the external plexiform layer. Dense NT- or NPY-IR fibers were distributed in superficial lamina of the granule cell layer, and sparse SP- or CCK-IR fibers were found in the glomerular layer. In the accessory olfactory bulb, some mitral, periglomerular, and granule cells showed NT-like immunoreactivity. SP- or ENK-IR granule cells were also observed. These results are discussed in relation to laminar organization of the olfactory bulb. The most characteristic features of peptide distribution in guinea pigs, as compared with that of rats in previous studies, were the relative abundance of NT-IR structures and the lack of SP- and CCK-IR juxtaglomerular and tufted cells.     

诱导性多潜能干细胞的应用前景

背景：通过基因转染的方式将已分化的体细胞重编程为诱导性多潜能干细胞,是近年来干细胞领域一项令人瞩目的新技术。由于诱导性多潜能干细胞摆脱了材料来源和伦理学的限制,因此其出现为特异的细胞治疗,特别是再生医学带来新的曙光。 目的：从诱导性多潜能干细胞的制备流程、产生的限制条件与机制、患者诱导性多潜能干细胞的获得及应用前景等方面做一评述。 方法：由第一作者检索PubMed数据库(www.ncbi.nlm.nih.gov/PubMed)2006-01/2010-03有关诱导性多潜能干细胞制备、产生机制的文章,检索词“induced pluripotent stem cells”,限定语言种类为English;同时手工检索部分文章。排除重复性研究,最终纳入34篇符合标准的文献。 结果与结论：诱导性多潜能干细胞系的建立主要包括以下几个步骤：①重组因子的选择。②目的细胞的选择。③重组因子的导入。④重组因子在目的细胞内的表达。⑤诱导性多潜能干细胞的产生。⑥重组细胞的鉴定。DNA甲基化、组蛋白的修饰作用和甲基化以及p53基因的表达在体细胞重编程为多潜能干细胞的过程中具有重要作用。虽然诱导性多潜能干细胞技术的研究仍然处于初级阶段,但是毫无疑问其具有广阔的应用前景。特别是患者特异性和疾病特异性诱导性多潜能干细胞的获得对于更好地理解疾病的发病机制及药物安全性评价提供了巨大的细胞种子资源。