Imatinib inhibits proliferation of human mesenchymal stem cells and promotes early but not late osteoblast differentiation in vitro

Altered bone metabolism has been reported in patients with chronic myeloid leukemia treated with the tyrosine kinase inhibitor imatinib. Several studies have shown that imatinib inhibits the differentiation and activity of osteoclasts in vitro, whereas the effects of imatinib on osteoblast differentiation are less clear. In this study osteoblast differentiation was induced in human mesenchymal stem cells (hMSCs) by treatment with bone morphogenetic protein 2 in vitro. Imatinib inhibited proliferation of hMSCs in a dose-dependent manner. Even though imatinib promoted early osteoblast differentiation assessed by alkaline phosphate activity, mineralization measured by Alizarin Red staining (ARS) was reduced by imatinib. Moreover, the inhibitory effect of imatinib on mineralization was most prominent at low concentrations of imatinib. When we measured the relative mRNA expression levels of Runx2, we found that Runx2 expression was higher in imatinib-treated (5 μM) cultures at early time points during differentiation. On the other hand, the expression of Osterix late during differentiation was lower in imatinib-treated (5 μM) cultures, corresponding to the ARS results. Thus, the effect of imatinib on osteoblast differentiation is not only dependent on the drug concentration, but indeed also on the maturation stage of the cells. This finding might partly explain why previous studies on the effects of imatinib osteoblast differentiation have shown different results.     

c-fos antisense DNA inhibits proliferation of osteoclast progenitors in osteoclast development but not macrophage differentiation in vitro

We previously reported that osteoclast formation in vitro, by coculture of mouse bone marrow and primary osteoblastic cells, occurs in two phases: proliferation of osteoclast progenitors followed by terminal differentiation into mature osteoclasts. Using this coculture system, we examined the effects of c-fos antisense and sense phosphorothioate oligonucleotides on osteoclast development and macrophage differentiation. Treatment with c-fos antisense for the first 4 days of coculture inhibited osteoclast formation in a dosedependent fashion. However, when c fos antisense was added during the second phase of coculture (4–6 days), osteoclast formation was unaffected. In contrast, c-fos antisense treatment had no effect on the appearance of F4/80 antigen-positive cells of the macrophage lineage in these cultures or on the induction by colony stimulating factor-1 of macrophage colony formation in cultures of mouse bone marrow cells in agar. Neither osteoclast differentiation nor macrophage appearance was inhibited by adding control c-fos sense in the cocultures. When c-fos antisense was added into an assay of bone resorption by mature osteoclasts, pit formation on dentine slices was unaffected. These results indicate that c-fos plays an important role in the proliferative phase of osteoclast progenitors in osteoclast development, but not in the terminal differentiation phase or in the bone resorbing activity of mature osteoclasts. c-fos antisense specifically inhibited osteoclast formation but had no effect on macrophage development.     

Nitrogen dioxide induces apoptosis and proliferation but not emphysema in rat lungs

BACKGROUND: Apoptosis of alveolar septal cells has been linked to emphysema formation. Nitrogen dioxide, a component of cigarette smoke, has been shown to induce alveolar epithelial cell apoptosis in vitro. It is hypothesised that exposure of rats to nitrogen dioxide may result in increased alveolar septal cell apoptosis in vivo with ensuing emphysema-that is, airspace enlargement and loss of alveolar walls. METHODS: Fischer 344 rats were exposed to 10 ppm nitrogen dioxide for 3, 7, 21 days or 21 days followed by 28 days at room air. Age-matched control rats were exposed to room air for 3, 21 or 49 days. Lungs fixed at 20 cm fluid column, embedded in paraffin wax, glycol methacrylate and araldite, were analysed by design-based stereology. Alveolar septal cell apoptosis (transferase dUTP nick end labelling assay, active caspase 3) and proliferation (Ki-67), airspace enlargement, total alveolar surface area, and absolute alveolar septal volume as well as the ultrastructural composition of the alveolar wall were quantified. RESULTS: Nitrogen dioxide resulted in an eightfold increase in alveolar septal cell apoptosis at day 3 and a 14-fold increase in proliferation compared with age-matched controls. Airspace enlargement, indicated by a 20% increase in mean airspace chord length, was evident by day 7 but was not associated with loss of alveolar walls. By contrast, nitrogen dioxide resulted in an increase in the total surface area and absolute volume of alveolar walls comprising all compartments. The ratio of collagen to elastin, however, was reduced at day 21. Lungs exposed to nitrogen dioxide for 21 days exhibited quantitative structural characteristics as seen in control lungs on day 49. CONCLUSIONS: Nitrogen dioxide exposure of rats results in increased alveolar septal cell turnover leading to accelerated lung growth, which is associated with an imbalance in the relative composition of the extracellular matrix, but fails to induce emphysema.     

Acute exposure to streptozotocin but not human proinflammatory cytokines impairs neonatal porcine islet insulin secretion in vitro but not in vivo

BACKGROUND: Neonatal porcine islets (NPI) are a potentially useful source of beta cells for transplantation to treat type 1 diabetes mellitus. However, cytokine exposure following xenotransplantation is likely to prevent successful NPI xenograft survival. In this study, we examined the effects of human proinflammatory cytokines (IL-1 beta, IFN gamma, TNFalpha) on NPI function and cell death. These cytokines have been shown to be cytotoxic to beta cells, in part through the generation of nitric oxide. Therefore, we also examined NPI function after acute oxidative stress caused by streptozotocin (STZ), a nitric oxide-generating beta cell cytotoxin. METHODS: Cultured NPI were exposed to human IL-1 beta, TNFalpha and IFN gamma for 48 h or STZ for 30 min in vitro. Cytokine exposed islets were transplanted into diabetic mice and assessed for function. Mice transplanted with control NPI were injected with STZ and also assessed metabolically. RESULTS: In vitro exposure to STZ, but not cytokines, significantly reduced NPI glucose stimulated insulin secretion (1.1 +/- 0.1 vs. 4.3 +/- 1.3-fold stimulation index in STZ vs. control, P < 0.05) in addition to cellular DNA recovery (57.6 +/- 4.4%, P < 0.05). Total cellular insulin content was significantly reduced in NPI exposed to either cytokines (56.6 +/- 8.1%) or STZ (45.7 +/- 1.6%) compared to controls (P < 0.05). Interestingly, both STZ and cytokines did not appear to negatively affect NPI function post-transplant. CONCLUSIONS: The potent nitric oxide generating cytotoxin STZ is able to impair in vitro NPI beta cell insulin release whereas human cytokines (IL-1 beta, TNFalpha, IFN gamma) do not affect the secretory response nor are they cytotoxic in vitro. These results may have implications for the development of anti-rejection protocols to be used in clinical NPI xenotransplants.     

Superior survival and proliferation after transplantation of myoblasts obtained from adult mice compared with neonatal mice

BACKGROUND: Myoblast transfer therapy (MTT) is a strategy designed to compensate for the defective gene in myopathies such as Duchenne muscular dystrophy (DMD). Experimental MTT in the mdx mouse (an animal model of DMD) has used donor myoblasts derived from mice of various ages; however, to date, there has been no direct quantitative comparison between the efficacy of MTT using myoblasts isolated from adult and neonate donor muscle. METHODS: Donor normal male myoblasts were injected into Tibialis Anterior muscles of dystrophic female host mice and the survival and proliferation of male myoblasts quantitated using Y-chromosome specific real-time quantitative polymerase chain reaction. The survival of late preplate (PP6) myoblasts derived from neonatal (3-5 days old) or adult (6-8 weeks old) donor mice after MTT were compared. The influence of the number of tissue culture passages, on survival post-MTT, was also evaluated for both types of myoblasts. RESULTS: Surprisingly, superior transplantation efficiency was observed for adult-derived compared with neonatal myoblasts (both early and late passage). Extended expansion (>17 passages) in tissue culture resulted in inferior survival and proliferation of both adult and neonatal myoblasts; however, proliferation of early passage myoblasts (both adult and neonate) was evident between 3 weeks and 3 months. CONCLUSIONS: Myoblasts derived from neonatal mice were inferior for transplantation, and early passage donor myoblasts from adult mice are recommended for MTT in this model.     

Early postoperative feeding in single-stage repair of anorectal malformation with vestibular or perineal fistula is not associated with increased wound complications

IntroductionThe objective of this study is to assess the postoperative outcomes of single-stage repair of anorectal malformations with vestibular (VF) or perineal fistula (PF) and early initiation of postoperative feeding.MethodsA retrospective review of patients undergoing single-stage repair of isolated low anorectal malformations (VF and PF) from 2017 to 2020 was conducted. All patients underwent an anterior anoplasty with complete mobilization of the rectal fistula, or posterior sagittal anorectoplasty (PSARP), without protective colostomy. The variables examined include age, timing of postoperative feeding initiation, length of stay (LOS), and complications.ResultsNineteen patients with VF or PF underwent a single-stage repair. 12/19 (63%) patients were female. All 7 males and 9/12 females had a PF. The range of age at surgery was 2 days to 3 years with median age of 92 days [IQR 1,3: 9,193]. The median postoperative day for initiation of feeds was day 0 [IQR 1,3: 0,1] and median LOS was 1 day [IQR 1,3: 1,4.5]. 18/19 (95%) patients were evaluated in follow-up and there were no wound infections, wound dehiscences, or recurrent fistulas. Within 90 days postoperatively, no patients were seen in the emergency department for postoperative issues. Within 6 months, 2/19 (11%) patients required an unplanned return to the operating room for anal dilation.ConclusionIn single-stage repair of isolated low anorectal malformations, VF and PF, early initiation of postoperative feeding is safe, results in a short length of stay, and does not lead to increased wound complications. Early enteral feeding eliminates the need for parenteral nutrition and central venous access, and their associated complications.Level of evidenceLevel IV     

Complex endovascular aneurysm repair is associated with higher perioperative mortality but not late mortality compared with infrarenal endovascular aneurysm repair among octogenarians

Objective

As our collective experience with complex endovascular aneurysm repair (EVAR) has grown, an increasing number of older patients are being offered endovascular repair of juxtarenal aneurysms. Outcomes after complex EVAR in this older subpopulation are not well-described. We sought to specifically evaluate clinical outcomes after complex EVAR compared with infrarenal EVAR in a cohort of octogenarians.

面部皮肤挫裂伤伴灰粒嵌入的急诊美容修复

目的:探讨颜面部软组织外伤伴灰尘颗粒嵌入的急诊美容修复技术和方法。方法:根据伤情,分别对62例灰尘颗粒创面进行急诊清创及美容外科修复。结果:本组62例灰尘颗粒创面,除2例因皮肤挫伤严重并缺损行肉芽创面植皮外,余均达到Ⅰ期修复并愈合,外伤性文身不明显。结论:遵循美容整形外科原则修复颜面部灰尘颗粒嵌入创面,可有效地减少伤后颜面部的外伤性文身、瘢痕畸形和医源性毁容。     

血清素对体外培养大鼠成骨细胞增殖分化和矿化功能的影响

目的 探讨不同浓度血清素对体外培养大鼠成骨细胞(OBs)增殖、分化和矿化功能的影响. 方法 在新生SD大鼠颅骨OBs培养液中分别加入不同浓度血清素:0 mol/L组(空白对照组)、10-9 mol/L组、10-8 mol/L组、10-7 mol/L组、10-6 mol/L组、10-5 mol/L组,观察不同浓度血清素对OBs的增殖能力(CCK-8法)、分化能力(Western法检测碱性磷酸酶蛋白水平、pNPP法检测碱性磷酸酶活性和ELISA法检测骨钙素蛋白表达水平)和矿化能力(茜素红染色)的影响.并用荧光定量聚合酶链反应方法检测OBs分化早、晚期血清素受体亚型的mRNA表达水平. 结果 不同浓度血清素均可抑制OBs的增殖、分化和矿化,这种抑制作用在低浓度时具有时间依赖性,而在高浓度时作用减弱,呈现“V”形趋势.5-HT1A、5-HT1B、5-HT1D、5-HT2A、5-HT2B、5-HT2C等受体在OBs上均有表达,其中5-HT2A和5-HT1B受体是表达最多的两种受体亚型. 结论 体外OBs表达血清素受体,血清素可抑制OBs的增殖、分化和矿化,提示血清素能够调节骨代谢.     

Complement (C5b-9) induces glomerular epithelial cell DNA synthesis but not proliferation in vitro.

BACKGROUND: The C5b-9 membrane attack complex of complement is the principal mediator of injury induced experimentally by antibodies directed at glomerular cell membranes. In experimental membranous nephropathy, C5b-9 induced injury to the glomerular visceral epithelial cell (VEC) is associated with DNA synthesis, but not cytokinesis. In the current study we determined if C5b-9 increases DNA synthesis in VEC in vitro, and defined the mechanisms involved. METHODS: Rat VEC in vitro were divided into three groups: (1) sensitized with anti-VEC antibody and exposed to sublytic concentrations of C +/PVG serum (normal complement components); (2) anti-VEC antibody and control C-/PVG serum (C6 deficient); (3) no anti-VEC antibody. DNA synthesis (BrdU staining), mitosis (mitotic figures) and cytokinesis (cell counts) were measured at 24 and 48 hours. To examine the expression of specific S-phase and M-phase cell cycle regulatory proteins and their inhibitors, immunostaining and Western blot analysis was performed for cyclin A, CDK2, p21 and p27, cyclin B and cdc2. RESULTS: In the absence of growth factors, sublytic C5b-9 attack did not increase proliferation. In contrast, sublytic C5b-9 attack (group 1) augmented growth factor induced DNA synthesis by 50% compared to controls (groups 2 and 3; P < 0.001), and was accompanied by increased levels of cyclin A and CDK2, and a decrease in the cyclin kinase inhibitor p27 (but not p21). Sublytic C5b-9 attack reduced the expression of the M phase cell cycle proteins, cyclin B and cdc2, accompanied by reduced mitosis (mitotic figures) and cytokinesis (cell number). CONCLUSIONS: Our results show that the C5b-9 augmented growth factor entry into the S phase in VEC is regulated by changes in specific cell cycle regulatory proteins. However, antibody and complement decreased the M phase cell cycle proteins, and prevented VEC mitosis and cytokinesis, suggesting a delay or arrest at the G2/M phase.     

Cardiac hypertrophy in the Prague-hypertensive rat is associated with enhanced JNK2 but not ERK tissue activity

Mitogen-activated protein (MAP) kinases are important intracellular mediators for proliferation and hypertrophy and therefore may also regulate cardiomyoblast growth in hypertensive heart disease. Thus, the aim of the present study was to examine the activities of MAP kinases, namely extracellular signal-regulated kinase (ERK)1,2, c-Jun NH2-terminal kinases (JNK)1,2 and p38 MAP kinase, in myocardial tissue of 12-week-old Prague normotensive (PNR) and hypertensive rats (PHR), a model of genetic hypertension with marked cardiac hypertrophy. Systolic blood pressure was 121 +/- 5 in PNR and 208 +/- 15 mm Hg in PHR (p < 0.01). Total heart weight was 247 +/- 4 in PNR vs. 316 +/- 4 mg/100 g body weight in PHR (p < 0.01). Left and right ventricular weights were 121 +/- 5 and 53 +/- 3 in PNR vs. 168 +/- 4 (p < 0.01) and 57 +/- 2 mg/100 g body weight (n.s.) in PHR. Using anti-ERK2 Western blot analysis as well as immunocomplex ERK activity assay, we found no activation of ERK2 in left or right ventricular tissue of PHR and PNR. Similary, p38 MAP kinase phosphorylation and activity were not detectable. In contrast, Western blot analysis using antiphospho-JNK antibodies revealed in myocardial tissue of right and left ventricles significantly greater phosphorylation of JNK2 in PHR than in PNR. This finding was confirmed by immunocomplex JNK activity assay using ATF-2 as substrate, which demonstrated a significant increase in JNK activity in the left ventricle of PHR as compared to PNR (6.4 +/- 1.5 vs. 2.5 +/- 0.5 OD; each n = 5; p < 0.05). In conclusion, cardiac JNK2 seems to be regulated differently from ERK2 in this rat model. In PHR, as compared to PNR, we found enhanced activity of JNK2 in the left and right ventricles suggesting that JNK2 is involved in hypertensive cardiac disease. The rise in JNK in both ventricles may result indirectly from humoral stimuli, e.g., endothelin-1 and/or angiotensin II, and may contribute to ventricular hypertrophy in this model of spontaneous hypertension.     

Factors associated with inguinal hernia repair in premature infants during neonatal admission

IntroductionTiming of inguinal hernia repair (IHR) in premature infants is variable and influenced by surgeon preference and complication profile. The purpose of this study was to evaluate factors related to early IHR, defined as hernia repair during initial neonatal admission, in premature infants.MethodsNeonatal hospitalizations of premature infants (gestational age at birth < 37 weeks and ≤ 28 days old at admission), with a diagnosis of inguinal hernia from 2010 to 2017 in HCUP National Inpatient Sample and Kid's Inpatient Sample databases were evaluated. Multivariable Cox proportional hazard models was used to estimate associations between demographics, additional procedures, hospital characteristics, and early IHR.ResultsOverall, 30,298 neonatal hospitalizations of premature infants with inguinal hernia were identified; 13,228 (43.3%) underwent early IHR. Early IHR was more likely with older gestational age at birth (35–36 weeks vs < 24 weeks, HR 6.05, 95% CI 4.17, 8.79), female sex (HR 1.20, 95% CI 1.07, 1.34), and undergoing concomitant gastrostomy (HR 2.51, 95% CI 1.72, 3.66). Non-Hispanic Black infants (HR 0.84, 95% CI 0.75, 0.95), infants at urban non-teaching hospitals (HR 0.15, 95% CI 0.07, 0.33), and infants at rural hospitals (HR 0.81, 95% CI 0.70, 0.97) were less likely to undergo early IHR.ConclusionsUsing a nationally representative database, early IHR in premature neonates was more commonly performed in non-Hispanic White, female neonates and at urban teaching hospitals. Patient race and hospital type were determinants of early IHR in premature neonates. There is a need to further evaluate the impact of race and socioeconomic factors on outcomes of common pediatric operations like inguinal hernia repairs.Level of EvidenceLevel III.     

GSB中药血清对rMSCs定向诱导分化为成骨细胞的影响

目的观察GSB中药血清对大鼠MSCs定向诱导分化成骨的影响。方法将培养的rMSCs分为对照组（C组）[含10%胎牛血清,100U/ml青霉素和100μg/ml链霉素的完全培养液]、诱导组（O组）[完全培养液,加诱导培养液（0.1μmol/L地塞米松、10mmol/Lβ-甘油磷酸钠及50μg/ml维生素C）,加20%空白血清]和含药血清诱导组（G组）[完全培养液加诱导培养液诱导培养液中加入20%含药血清）。显微镜下观察细胞形态变化,生化法测定上清中Ca^2＋浓度,Gomori改良钙钴法进行ALP染色,Von Kossa法进行矿化结节染色,RT-PCR法测定Ⅰ型胶原（COLL1）和脂蛋白脂酶（LPL）的表达,放免法测定上清中骨钙素含量。结果O组和G组在加入诱导培养液3-4天后梭形细胞比例减少,细胞变形成多角形、乃至方形,部分区域细胞成多层生长;改良Gomori钙钻法碱性磷酸酶染色阳性细胞,Von Kassa染色发现钙盐沉积;培养9d后细胞Ca^2＋浓度开始升高,并随时间持续显著增长,且G组明显高于O组。自第15d后,O组和G组细胞ALP活性随时间延长而明显增高,且G组显著高于O组;培养的第14d,G组骨钙素分泌量明显高于O组。成骨诱导剂作用MSCs12d后,COLLⅠ mRNA表达阳性,LPL mRNA表达阴性,且G组比O组COLLⅠ mRNA表达更强。结论补肾填精中药GSB促进骨钙素分泌、增强ALP活性、促钙盐沉积,具有增强成骨诱导剂诱导rMSCs向成骨细胞分化,并促进成骨细胞成熟作用。     

Complement activation at the interface of wound dressings and blood does not influence keratinocyte migration/proliferation in vitro

Recently, we reported that some wound dressings caused complement activation at the interface of wound dressing and blood. Since complement activation is associated with impaired wound healing, we investigated whether this activation of the complement cascade at the interface of wound dressings and blood does impair reepithelialization in a scratch wound healing assay. Although some samples showed higher levels of the complement activation marker SC5b‐9 in our study, reepithelialization of the samples did not significantly differ from the control group. Further studies have to clarify if complement activation at the interface of wound dressings and blood plays a relevant role in the healing process especially in long‐time experiments.     

羊胎素对体外成骨细胞增殖、分化及矿化功能的影响

目的 观察羊胎素在体外对新生大鼠颅骨成骨细胞增殖、分化及矿化功能的影响。方法将提取之羊胎素稀释加入体外培养的SD新生大鼠颅骨成骨细胞体系中,终浓度分别为0.625％、1.25％、2.5％、5％和10％;加药后24、48和96 h用MTT法检测细胞的增殖并绘制生长曲线:培养5 d时用PNPP法测定细胞碱性磷酸酶(ALP)活性;培养31 d时用茜素红染色2.5％羊胎素组形成之矿化骨结节,用图像分析仪计算骨结节的面积。结果 所有含羊胎素浓度组,其MTT法测得的A值都显著高于空白对照组(P<0.01),生长曲线表现为含羊胎素组的细胞增殖加快,以2.5％浓度组最为显著;ALP结果显示,羊胎素各浓度组的碱性磷酸酶活性都显著高于空白对照组(P<0.01);茜素红染色后显示,2.5％羊胎素组所形成的骨结节面积显著高于空白对照组(P<0.01)。结论羊胎素对体外培养的SD新生大鼠颅骨成骨细胞有显著的促进增殖、分化和矿化的作用。     

Ropivacaine 0.25% and 0.5%, but not 0.125%, provide effective wound infiltration analgesia after outpatient hernia repair, but with sustained plasma drug levels

BACKGROUND AND OBJECTIVES: Ropivacaine is a long-acting local anesthetic similar to bupivacaine, but with lower cardiac toxicity and intrinsic vasoconstrictive properties that may reduce the risk and extent of systemic plasma absorption. Plasma levels and risks are associated with the total dose used and the extent of absorption, with lower doses potentially representing less risk. Although both 0.5% and 0.75% ropivacaine provide adequate analgesia for wound infiltration after hernia repair, the efficacy of lower doses and the early systemic absorption have not been reported. METHODS: We studied postoperative pain and systemic plasma levels following either the injection of 30 mL of saline or 0.125%, 0.25%, or 0.5% ropivacaine into the wounds in 110 healthy patients following hernia repair under spinal anesthesia. Pain was assessed using visual analog scale (VAS) scores and algometer readings at rest and after coughing, and oral analgesic requirements were assessed in the first 5 hours after surgery and for the week after discharge. RESULTS: Both 0.25% and 0.5% ropivacaine provided pain relief following surgery when compared with saline or 0.125%. No adverse reactions to the drug were reported in any group. Plasma levels of ropivacaine peaked between 30 and 60 minutes, at 0.109, 0.249, and 0.399 mg/L for 0.125%, 0.25%, and 0.5% concentrations, respectively. Although the levels were below those producing clinical symptoms, they remained elevated for the entire 2-hour sampling period. This implies an absorption-dependent elimination which is substantially longer than reported with other routes of injection. CONCLUSIONS: Ropivacaine 0.25% and 0.5% is adequate for pain relief after outpatient hernia repair, whereas the 0.125% solution is no more effective than saline. Prolonged systemic absorption from peripheral injection may be associated with prolonged elevations of plasma concentrations, which potentially could be associated with unexpectedly high plasma levels if repeated injections are performed in the perioperative period with higher concentrations or doses.     

Transient neutropenia increases macrophage accumulation and cell proliferation but does not improve repair following intratendinous rupture of Achilles tendon

Neutrophils are the first leukocytes to invade tendons after an acute injury. They could modulate both the inflammatory response and early repair processes through the release of reactive species, cytokines, growth factors, and proteinases. However, the exact role of these cells in damaged tendons remains unclear. We investigated their role by inducing a transient neutropenia in C57BL/6 male mice using an anti‐Ly6C/Ly6G antibody. Placebo mice received only serum. The right Achilles tendon was sectioned and sutured using the 8‐strand technique, which allowed immediate weight bearing. A significant increase in macrophage accumulation and cell proliferation was observed in tendons from neutropenic animals compared to the placebo group at days 3 and/or 7 postinjury. However, there was a reduction in cell proliferation in a group of mice depleted in macrophages, indicating that macrophages play a role in cell replication in injured tendons. Lastly, the tendons of neutropenic and placebo mice had similar collagen content and mechanical properties at days 7, 14, and/or 28 postinjury. Our findings demonstrate that neutropenia modulates macrophage accumulation and cell proliferation, but overall, a reduction in neutrophil number has no significant effect on tendon repair. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:1084–1091, 2010     

Uraemic medium accelerates proliferation but does not induce apoptosis of endothelial cells in culture.

BACKGROUND: Chronic renal failure patients exhibit accelerated atherosclerosis, which is associated with a high incidence of cardiovascular death. We investigated the potential effect of uraemic medium on cell proliferation and apoptosis of endothelial cells in culture (ECs), two key processes in the development of atherosclerosis. Phosphorylation kinetics of the mitogen-activated protein kinase (MAPK) p42/44 and p38 were also evaluated. METHODS: ECs were cultured with growth media supplemented with pooled sera from healthy donors. Semiconfluent ECs were incubated for 24 h with media supplemented with pools of control or uraemic sera. Cell proliferation was assessed through morphometric analysis and by flow cytometry evaluation of cell cycle. To investigate if uraemic medium induces apoptosis in ECs, we used a combination of terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL) assay and activation of caspase-3 using flow cytometry. Changes in the phosphorylation levels of MAPK were evaluated in cell lysates by western blotting. RESULTS: Exposure to uraemic media caused an alteration in the morphology of ECs, showing irregular shape and size. The number of ECs at S+G(2)M phase in the cell cycle was found to be increased when exposed to uraemic media for 24 h (28.4+/-2.9 vs 20.2+/-2.6% in control ECs). There was a transient increase in levels of phosphorylation of MAPK in both cells, although these levels were significantly higher in ECs exposed to uraemic media, especially after 5 min. In contrast, no signs of apoptosis were observed in ECs incubated with uraemic medium at the conditions applied. CONCLUSIONS: Under our experimental conditions, uraemic medium accelerates proliferation of ECs, but it does not seem to induce apoptosis. The increased proliferation observed could be related to a higher MAPK activity in these cells. Although the enhanced atherosclerosis cannot be explained on the basis of an apoptotic process, the proliferative status could contribute to intimal proliferation, which is considered to be an earlier step in the development of atherosclerosis.