染氟成纤维细胞超微结构和细胞周期的改变及其意义

目的研究氟化物对成纤维细胞超微结构和细胞周期方面的影响。方法将成纤维细胞分为不同氟剂量组(0、0.000 1、0.001、0.01、0.1、1、10和20 mg/L),染氟48 h。应用透射电镜和流式细胞术分别观察成纤维细胞的超微结构改变和细胞周期变化。结果染氟成纤维细胞内粗面内质网明显扩张,高尔基体、脂滴和糖原增多,未见细胞毒性颗粒;染氟0.1 mg F-/L组G0-G1期细胞百分率低于未染氟组(分别为48.8%和54.0%);染氟组S期细胞百分率高于未染氟组(未染氟组为31.7%,染氟0.000 1、0.001、0.1、1、10和20 mg F-/L组则分别为32.4%、46.1%、32.4%、35.1%和33.7%);同时发现染氟组成纤维细胞凋亡数较未染氟组减少(未染氟组凋亡细胞数为3.1%,染氟0.000 1、0.001、0.1、1、10和20 mg F-/L组分别为2.6%、2.5%、1.3%、0.8%、0.5%和1.9%)。结论染氟可明显刺激成纤维细胞增殖、合成和分泌功能,并降低细胞凋亡百分率。     

氟对小鼠成骨细胞增殖的影响

目的 观察氟对体外培养小鼠成骨细胞增殖的影响。方法 原代培养小鼠成骨细胞，以0（对照组）、5、10、20、40mg／L剂量染氟，光、电镜观察成骨细胞的形态学变化；采用生长曲线、噻唑蓝（MTT）法及流式细胞仪检测细胞周期，观察细胞数量变化和细胞周期时相分布。结果 第10天时，5、10、20mg／L染氟组从形态学上表现出细胞增殖。而40mg／L组中出现细胞凋亡。染氟24h时，20mg／L组与对照组相比细胞增殖明显，差异具有统计学意义（P〈0．05），随着时间延长，染氟组表现出更强的增殖活性，至72h时，各染氟组成骨细胞增殖均高于对照组（P〈0．05）。24h时各染氟组间细胞增殖水平未见明显差异（P〉0．05），48h以后40mg／L组明显低于其他各染氟组（P〈0．05）。而染氟72h时5mg／L组增殖强度也低于10、20mg／L组（P〈0．05）。与对照组相比，10、20mg／L组处于G0／G1期的细胞数减少，而S期细胞数增加（P〈0．05），同时两组的细胞增殖指数也高于对照组（P〈0．05），生长表现出增殖状态；其中10mg／L组与其他染氟组之间，差异有统计学意义（P〈0．05），表现为细胞增殖能力增强。结论 低剂量的氟在较短作用时间内可以促进体外培养小鼠成骨细胞增殖，随剂量增加和暴露时间延长其促进作用减弱。     

丹皮酚对人乳腺导管癌细胞MDA-MB-435增殖的影响

目的 观察丹皮酚对人乳腺癌细胞MDA-MB-435增殖的影响及其抑制机制.方法 应用MTT法观察丹皮酚对MDA-MB-435细胞的细胞毒作用；应用苏木精-伊红(HE)染色观察丹皮酚对细胞形态学的影响；流式细胞仪检测丹皮酚处理MDA-MB-435细胞后细胞周期的变化.结果 丹皮酚作用于MDA-MB-435细胞的IC50为60 mg/L;60 mg/L的丹皮酚作用于MDA-MB-435细胞24、48 h后,细胞生长受到不同程度的抑制,出现细胞变圆,体积缩小,胞浆起泡,部分细胞浮起,胞膜皱缩,核深染等形态学改变.肿瘤细胞周期在G0/G1期百分数增加,S期和G2/M期百分数减少,出现Sub-G1期凋亡峰,百分率分别为12.4％和23.7％.结论 丹皮酚通过影响MDA-MB-435细胞周期和诱导凋亡而抑制MDA-MB-435增殖.     

过量氟对大鼠脑肝肾细胞周期与细胞凋亡的影响

目的 研究氟对大鼠脑、肝、肾组织细胞凋亡和细胞周期的作用特点与 氧化侵袭之间的关系,进一步探讨氟中毒发生机理。方法 在常规食、偏食条件下,经饮水投不同剂量氟,应用流式细胞仪方法检测脑肝、肾组织细胞凋亡,细胞周期与活性氧产生状态。结果 常规食投氟100－150mg/L、偏食投氟50－100mg/L对脑、肝、肾组织活性氧产生无明显影响。氟对脑组织神经细胞周期的影响主要在S期,可明显减少S期神经细胞数量;对肝细胞周期的作用主要在G1期和G2期,偏食投氟各组G1期细胞数目普遍低于常食投氟组,G2期细胞数目则高于常规投氟组。过量氟对肾组织的作用,主要为偏食投氟100mg/L情况下,可明显诱导细胞凋亡的变化。结论 过量氟对细胞周期的影响,对不同组织的作用时相似有一定程度的差别,对脑神经细胞主要作用于S期,肝细胞的影响主要是G1、G2期;对肾细胞主要表现为诱导细胞凋亡过程。     

氟致离体人肝细胞凋亡及硒的保护作用研究

目的 研究硒、氟对离体人肝细胞周期和凋亡的影响。方法 体外培养的人肝细胞接触氟和（或）硒12h后,用流式细胞仪检测肝细胞凋亡百分率和细胞周期构成比。结果 氟可使肝细胞凋亡百分率明显升高,S期细胞数增加,但G0／G1期和G2／M期细胞数无明显改变;加硒可明显拮抗氟的这种影响。结论 氟对人肝细胞的损害与氟诱导细胞凋亡和改变细胞周期分布有关,一定 量的硒可明显拮抗氟诱导的肝细胞凋亡及其对细胞周期的影响。     

蛋白酶体抑制剂MG-132对SHG-44细胞的体外实验研究

目的探讨蛋白酶体抑制剂MG-132对人胶质瘤SHG-44细胞增殖、细胞凋亡及细胞周期的影响。方法分别以不同浓度(5、10、20、50μmol/L)的MG-132培养SHG-44细胞。MTT法检测不同培养时间细胞增殖活力、流式细胞术检测细胞凋亡及周期、AO/EB及HE染色观察细胞凋亡变化。结果MG-132可显著抑制SHG-44细胞生长,24h时其抑制作用尤为明显,与对照组相比,5、10、20、50μmol/L浓度组细胞增殖OD值均显著低于正常对照组(P<0.01),呈现剂量依赖性抑制作用增强趋势。与正常对照组相比,MG-132处理SHG-44细胞后,于5μmol/LMG-132作用12h后即可检测到明显的凋亡亚二倍体峰,且存在时效及量效关系;同时24h各剂量MG-132处理组G2/M期细胞表达百分率显著高于正常对照组(P<0.01),S期细胞表达百分率显著低于正常对照组(P<0.01)。结论蛋白酶体抑制剂MG-132在体外可显著诱导人脑胶质瘤SHG-44细胞发生凋亡、G2/M期细胞周期阻滞并抑制细胞增殖。     

阿奇霉素诱导淋巴细胞白血病Jurkat细胞凋亡作用的研究

目的：研究阿奇霉素诱导淋巴细胞白血病Jurkat细胞凋亡作用,及其相关的凋亡蛋白和细胞周期的变化,为临床治疗淋巴细胞白血病提供新的研究思路。方法：应用Annexin V-FITC/PI双染法流式细胞术检测细胞凋亡并用流式细胞术进行细胞周期分析,MTT法检测阿奇霉素对Jurkat细胞的增殖抑制作用,利用West-ern-blotting检测凋亡途径相关蛋白的表达。结果：用阿奇霉素处理Jurkat细胞48h后300mg/L剂量组早期凋亡率显著增高达到（88.0&#177;3.3）%,而25mg/L剂量组为（11.5&#177;2.7）%,与对照组（10.6%&#177;1.8）%无明显差异。MTT法检测结果IC50值为88.4mg/L,200mg/L抑制率达到89.27%。细胞周期显示150mg/L时G1期细胞增加,G2期和S期细胞下降。Western-blotting结果表明Bcl-2蛋白高表达,处理前后无明显变化,而Bax蛋白表达随药物浓度提高而上升,活化的Caspase3在100mg/L表达最高。结论：阿奇霉素可以有效的诱导Jurkat细胞凋亡并呈明显的浓度依赖性,其凋亡途径可能是通过Bax蛋白表达上升诱导下游效应分子Caspase3活化实现。细胞增殖抑制试验表明200mg/L以上时细胞增殖明显受抑制,细胞周期分析提示细胞增殖阻滞在了G1期。     

RNAi沉默PTTG基因对恶性胶质瘤U251细胞的影响

目的探讨垂体瘤转化基因（PTTG）siRNA干扰质粒对人脑胶质瘤细胞株U251体外增殖、周期和凋亡的影响。方法利用脂质体将pGenesi1-2 PTTG siRNA干扰质粒转染U251细胞，通过MTT法观察转染后24h,48h和72h细胞增殖的变化、流式细胞术PI单染观察转染后48h细胞凋亡和细胞周期的变化。结果pGenesi1-2 PTTG siRNA干扰质粒转染U251细胞48h后。PTTG mRNA和蛋白的抑制率分别约为69％和71％；阻滞U251细胞由G1期进入S期，抑制细胞的生长，增加了细胞的凋亡。结论PTTG siRNA表达载体可以特异高效地抑制胶质瘤U251细胞PTTG基因的表达，从而调控肿瘤细胞周期，抑制肿瘤细胞增殖。     

环氧合酶-2抑制剂celecoxib抑制胃癌生长的实验研究

目的研究celecoxib在体内外对胃癌增殖及凋亡的影响.方法不同浓度celecoxib处理体外培养的SGC7901细胞后,采用噻唑蓝(MTT)法检测处理后24、48、72、96小时SGC7901细胞的增殖活性,流式细胞仪测定细胞周期和细胞凋亡.利用SGC7901胃癌细胞株建立裸鼠胃癌种植瘤模型,实验组予以celecoxib 10 mg/Kg/day灌胃,共给药6周.结果 25,50,100,200μmol/Lcelecoxib处理SGC7901细胞24、48、72、96小时后,细胞增殖明显受到抑制,呈时间和剂量依赖性特点.50 μmol/L celecoxib处理SGC7901细胞24 h后,流式细胞仪细胞周期分析表明G0/G1期细胞百分率上升,S期和G2/M期细胞百分率下降.流式细胞仪检测实验组的凋亡率明显高于对照组(20.4±2.8%vs 7.6±0.6%,P＜0.05).celecoxib治疗组裸鼠胃癌种植瘤重量为(0.43±0.21)g,明显低于对照组(1.33±0.45)g(P＜0.05).结论体内及体外实验表明,celecoxib能有效抑制胃癌生长,其机制可能与其阻滞细胞周期及诱导凋亡有关.     

原花青素对HL-60细胞分化及凋亡的影响

目的探讨原花青素(PAC)对HL-60细胞增殖、诱导分化及凋亡的影响。方法 HL-60细胞经不同浓度的PAC作用相应时间后,用CCK-8法检测细胞生长状况,分析PAC对HL-60细胞增殖抑制;Wright染色,光学显微镜观察细胞形态变化;通过流式细胞仪检测分析细胞周期变化和测定髓系较成熟阶段细胞分化抗原CD14、CD11b的表达。结果用不同终浓度PAC在体外与HL-60细胞共培养,细胞抑制率随浓度增加而明显增高,与对照组比较,差异有统计学意义(P<0.05),其中浓度为20 mg/L的PAC作用HL-60细胞24 h,增殖抑制率为(72.3±1.8)%,高浓度PAC与HL-60体外培养72 h,部分细胞死亡;20 mg/L的PAC诱导HL-60细胞24 h,少数细胞出现核凹陷变形,作用48 h部分细胞分化为较成熟阶段细胞,40 mg/L的PAC作用HL-60细胞48 h,细胞出现凋亡改变;20 mg/L的PAC诱导HL-60细胞24 h,细胞周期G0/G1期百分比明显增高,S期细胞数明显减少,而40 mg/L的PAC作用HL-60细胞24 h,细胞周期G2/M期细胞百分比明显增高,并出现凋亡峰。20 mg/L的PAC诱导HL-60细胞24 h,流式细胞检测髓系细胞分化抗原CD14表达明显增高,CD11b表达稍增高。结论 PAC能抑制HL-60细胞增殖,低浓度PAC诱导其分化为较成熟阶段细胞,高浓度PAC则可能诱导HL-60细胞发生凋亡。     

Erythrocyte-endothelial cell adherence in sickle cell disorders

Detachment of individual sickle erythrocytes from cultured endothelial cell monolayers has been evaluated by a fluid-shearing technique in an effort to quantitate adherence at shear forces that would be anticipated in the in vivo circulation. Nonirreversibly sickled cells (non-ISC) were more adherent at normal oxygen tensions than control cells. More than 1% non-ISC remained attached to the monolayer at forces greater than physiologic shear stresses in capillary and venous circulations, and many of the most avidly attached cells, once separated, immediately reattached to adjacent endothelial cells. These data suggest that hemoglobin S-containing erythrocytes may have a higher frequency of adherence in vivo in regions of low shear stress where prolonged erythrocyte-endothelial cell contact could occur. Some of these cells detached by shear force would subsequently reattach in in vivo conditions. Plasma-enhanced attachment frequency and plasma from blood in a case of sickle crisis caused further increase. These observations further support the concept that sickle erythrocyte- endothelial cell interaction may be a significant factor in initiation of vascular occlusive events in sickle cell disease.     

Liver cell adenoma and liver cell adenomatosis

During the last three decades liver cell adenoma and liver cell adenomatosis have emerged as new clinical entities in hepato-logical practice due to the widespread use of oral contraceptives and increased imaging of the liver. On review of published series there is evidence that 10% of liver cell adenomas progress to hepatocellular carcinoma, diagnosis is best made by open or laparoscopic excision biopsy, and the preferred treatment modality is resection of the liver cell adenoma to prevent bleeding and malignant transformation. In liver cell adenomatosis, the association with oral contraceptive use is not as high as in solitary liver cell adenomas. The risk of malignant transformation is not increased compared with solitary liver cell adenomas. Treatment consists of close monitoring and imaging, resection of superficially located, large (>4 cm) or growing liver cell adenomas. Liver transplantation is the last resort in case of substantive concern about malignant transformation or for large, painful adenomas in liver cell adenomatosis after treatment attempts by liver resection.     

Red cell alloimmunization in sickle cell disease

Alloimmunization to red cell antigens contributes to morbidity in transfused patients. It has been recommended that blood for sickle cell patients need not be matched for antigens other than ABO and Rh(D), as there is no greater incidence of antibody production than in other multitransfused patient populations. Post transfusion alloimmunization was studied in a group of 34 sickle cell disease patients attending a U.K. haemoglobinopathy clinic. Red cell antibodies were formed in 17.6% of the transfused patients and Rhesus and Kell antibodies accounted for 66% of this total. In order to reduce alloimmunization, a policy of performing extended red cell phenotyping on the patients, and providing blood matched for Kell, and in certain circumstances the Rhesus antigens other than Rh(D), is recommended.     

Misdiagnosis of clear cell renal cell carcinoma

Clear cell renal cell carcinoma (RCC) represents the most common histological subtype of malignant kidney tumors. Based on symptoms alone, clear cell RCC is indistinguishable from other histological classes of RCC unless the tumor is present in the context of an RCC syndrome. Histopathological examination is, therefore, important to accurately identify clear cell RCC. Clear cell RCCs have characteristic morphological criteria; these tumors can be easily identified upon typical presentation, but diagnosis can be challenging when tumor cell pattern is unusual or when availability of tissue samples is limited. In this Review, the clinical, radiological and pathological characteristics of clear cell RCCs are described, as well as the potential tumors that can be confused with clear cell RCC and need to be considered in the differential diagnoses. Finally, the importance of an accurate diagnosis is highlighted in the context of the increasing use of preoperative tissue sampling and the prevalence of clear cell tumors associated with hereditary syndromes, which could have different therapeutic and prognostic implications for patients and their families.     

Red cell exchange in sickle cell disease

Red cell exchange transfusion is frequently of use in the management of patients with sickle cell disease either electively or therapeutically. Modern cell separators allow this procedure to be performed rapidly, effectively and safely. These machines have a number of advantages over manual exchange procedures. The patient remains isovolaemic, there is little loss of plasma or platelets, the procedure is relatively short and in elective circumstances can be performed on an outpatient basis. In this series 66 exchanges were performed on 21 patients with an overall increase in HbA of 70%. The COBE Spectra gave a mean increase in HbA of 77%, with the majority of patients achieving an HbA of > 90% post exchange. Automated redcell exchange was well tolerated by most patients, and adverse effects were limited to symptoms of hypocalcaemia which were easily treated, and to transfusion reactions. Cell separators can therefore be recommended for exchange transfusion in patients with sickle cell disease, who require an increase in HbA levels either prophylactically or therapeutically. They are safe, effective, easy and quick to use.     

Actin filament debranching regulates cell polarity during cell migration and asymmetric cell division

The formation of the branched actin networks is essential for cell polarity, but it remains unclear how the debranching activity of actin filaments contributes to this process. Here, we showed that an evolutionarily conserved coronin family protein, the Caenorhabditis elegans POD-1, debranched the Arp2/3-nucleated actin filaments in vitro. By fluorescence live imaging analysis of the endogenous POD-1 protein, we found that POD-1 colocalized with Arp2/3 at the leading edge of the migrating C. elegans neuroblasts. Conditional mutations of POD-1 in neuroblasts caused aberrant actin assembly, disrupted cell polarity, and impaired cell migration. In C. elegans one-cell−stage embryos, POD-1 and Arp2/3, moved together during cell polarity establishment, and inhibition of POD-1 blocked Arp2/3 motility and affected the polarized cortical flow, leading to symmetric segregation of cell fate determinants. Together, these results indicate that F-actin debranching organizes actin network and cell polarity in migrating neuroblasts and asymmetrically dividing embryos.

Cell polarity is a fundamental feature of virtually all eukaryotic cells and plays crucial roles in a wide range of cellular processes, including cell motility, asymmetric cell division, and cell signaling (1). The establishment of cell polarity involves the asymmetric assembly of distinct cellular components to perform specialized functions. The actin-related protein (Arp) 2/3 complex-dependent branched actin networks and the pushing force they produce provide the principal means for cells to remodel the plasma membrane during cellular polarization (2). For example, in the leading edge of a migrating cell, the local Arp2/3-nucleated actin polymerization powers asymmetric projections of the plasma membrane (3). During asymmetric cell division of the Caenorhabditis elegans zygote, an actomyosin flow is central to the transport of the polarity PAR proteins into defined subcellular domains (4).Actin filaments'' continuous assembly must be balanced by actin depolymerization to ensure a constant supply of actin monomers for new growth. The Arp2/3 complex potency in actin nucleation empowers this complex as an essential regulator to organize the actin cytoskeleton. While Arp2/3 by itself is biochemically inactive, interactions with nucleation-promoting factors (NPFs) such as the Wiskott Aldrich syndrome protein (WASP)/WASP family verproline-homologous (WASP/WAVE) family proteins shift the Arp2/3 complex from its open, inactive conformation to a closed, active conformation (5, 6). The conformationally activated Arp2/3 complex then binds to the side of preexisting actin filaments to nucleate a branch from the mother filament (7–12). Conversely, nucleation by Arp2/3 can be inhibited by several binding partners, including glia maturation factor (GMF), Gadkin, Arpin, and Coronin, whose activities replenish available pools of actin monomers and Arp2/3 complexes for sustained actin assembly (13–18).The coronin family proteins are conserved actin regulators (19). The phylogenetic analysis grouped coronin genes into three types (19, 20). The best-characterized coronin is the Type I coronin (e.g., Coronin 1B) that binds to actin filaments through the β-propeller structure and to the Arp2/3 complex via its N terminus. These interactions block the docking of Arp2/3 onto actin filaments or facilitate debranching the existing actin network (20). Coronin 1B simultaneously interacts with the Slingshot phosphatase to dephosphorylate and activate ADF/Cofilin proteins that sever actin filaments, thereby promoting the actin network disassembly (13). Despite significant progress on Type I coronin, the activity and function of other coronins remain unclear. In particular, Type III coronins, known as POD-1 in C. elegans and Drosophila or Coronin7 in Dictyostelium and humans, contain two tandem coronin repeats, making them distinct from other coronins (19–21). POD-1 was biochemically isolated from C. elegans oocytes (22), and its mutations disrupted the polarity and architecture in early C. elegans embryos and impaired midlife touch sensitivity of the nematode (21, 23). However, it remains unclear how the Type III coronin functions. The Drosophila homolog of POD-1 is required for correct axon guidance, and the purified Dpod-1 cross-links the actin and microtubule cytoskeletons (24), whereas the mammalian Coronin7 was implicated in the Golgi morphology and function (25, 26), demonstrating the functional divergence of this family of coronin. Here, we show that the C. elegans POD-1 debranches Arp2/3-nucleated actin filaments in vitro and that POD-1 regulates cell polarity by remodeling the actin cytoskeleton during cell migration and asymmetric cell division.     

Sphere-forming cell subpopulations with cancer stem cell properties in human hepatoma cell lines

Background

Cancer stem cells (CSCs) are regarded as the cause of tumor formation and recurrence. The isolation and identification of CSCs could help to develop novel therapeutic strategies specifically targeting CSCs.

Methods

Human hepatoma cell lines were plated in stem cell conditioned culture system allowed for sphere forming. To evaluate the stemness characteristics of spheres, the self-renewal, proliferation, chemoresistance, tumorigenicity of the PLC/PRF/5 sphere-forming cells, and the expression levels of stem cell related proteins in the PLC/PRF/5 sphere-forming cells were assessed, comparing with the parental cells. The stem cell RT-PCR array was performed to further explore the biological properties of liver CSCs.

Results

The PLC/PRF/5, MHCC97H and HepG2 cells could form clonal nonadherent 3-D spheres and be serially passaged. The PLC/PRF/5 sphere-forming cells possessed a key criteria that define CSCs: persistent self-renewal, extensive proliferation, drug resistance, overexpression of liver CSCs related proteins (Oct3/4, OV6, EpCAM, CD133 and CD44). Even 500 sphere-forming cells were able to form tumors in NOD/SCID mice, and the tumor initiating capability was not decreased when spheres were passaged. Besides, downstream proteins DTX1 and Ep300 of the CSL (CBF1 in humans, Suppressor of hairless in Drosophila and LAG1 in C. elegans) -independent Notch signaling pathway were highly expressed in the spheres, and a gamma-secretase inhibitor MRK003 could significantly inhibit the sphere formation ability.

Conclusions

Nonadherent tumor spheres from hepatoma cell lines cultured in stem cell conditioned medium possess liver CSC properties, and the CSL-independent Notch signaling pathway may play a role in liver CSCs.     

Mechanism of red blood cell aging: Relationship of cell density and cell age

The human red cell has a life span of 120 days. The mechanism that determines cell removal from the circulation with such precision remains unknown. Most studies of red cell aging have been based on analysis of cells of progressively increasing age separated by density. The relationship between red cell age and density has been recently challenged, and the hypothesis has been put forward that cell death is not the result of a progressive deterioration of essential cell constituents. This theory was based on preliminary observations in transient erythroblastopenia of childhood, which could not later be confirmed. When the relationship between cell aging and increasing density is critically reviewed, it appears to be based on firm experimental evidence, confirmed by in vivo demonstration of decreasing survival of cells of increasing age. Analysis of studies using buoyant density gradients reveals that this technique can easily distinguish the single exponential slope of decline for those cell components that change progressively throughout the red cell life span from the biphasic decline of those that decrease drastically at the reticulocyte-mature red cell transition. The view that the aging of the red cell and its removal from the circulation result from a progressive series of events during the 120 days of its life span appears to be the most consistent with the available data. Density separation, validated by much experimental evidence, remains a most useful technique for the study of the mechanism of aging of the red cell. © 1993 Wiley-Liss, Inc.     

Red cell rheology in stomatocyte-echinocyte transformation: roles of cell geometry and cell shape

The influence of the shape of the red blood cell during stomatocyte- echinocyte transformation on its deformability was studied by microsieving through pores with diameters of 2.6, 4.5, and 6.9 micron. A stomatocytic transformation was produced by chlorpromazine (0.02, 0.1, and 0.5 mmol/L) and an echinocytic transformation by sodium salicylate (7.5, 30, and 120 mmol/L). For spherostomatocytes, an increase in filtration resistance through 2.6 and 4.5 micron pores was observed, whereas for spheroechinocytes, a decrease in filtration resistance through 2.6 micron pores was found. Larger pores (6.9 micron) were not sensitive to those shape changes. The changes in deformability can be explained by the fact that the surface area of (sphero)-stomatocytes decreased, whereas that of (sphero)-echinocytes increased; the cell volume remained essentially constant. Echinocytes produced by 24-hour adenosine triphosphate depletion differed from drug- induced echinocytes: they had an increased cell volume at constant surface area and consequently an increased filtration resistance through 2.6- and 4.5-micron filter pores. Shape changes with spicule formation are therefore not a homogeneous entity, and cell geometric factors (eg, surface area and volume) must be assessed with care. The viscosity of red cell suspensions at a hematocrit level of 45% was higher for drug-induced echinocytes than discocytes or stomatocytes at all shear rates tested. We conclude that the normal discocyte represents an optimum shape for the flow in vivo since a stomatocytic transformation could impair the passage through the microcirculation (decrease in cell filterability) and an echinocytic transformation could impair the flow in larger vessels (increase in blood viscosity).     

Automated red cell exchange in sickle cell disease

We used multiple optical trapping to study the mechanism of red cell (dis)aggregation. Two sets of optical 'tweezers' were used to bring two red blood cells together to form a two-cell aggregate and then to pull them apart, to study the interaction between the cells.
We found that cross-bridging occurred in normal reversible aggregation as we observed binding and the occurrence of small tethers between opposite cell membranes. Furthermore, the cells could only be parted by sliding them side by side with a maximum velocity in the order of μm/s indicating accumulation of the cross-bridges.