Effect of human endothelial cells on human bone marrow stromal cell phenotype: role of VEGF?

Angiogenesis is a tightly regulated process involved in growth, repair, and bone remodeling. Several studies have shown that there is a reciprocal regulation and functional relationship between endothelial cells and osteoblast-like cells during osteogenesis, where systemic hormones and paracrine growth factors play an active role. Angiogenesis is induced by a variety of growth factors; among them vascular endothelial growth factor (VEGF) may be an important mediator for the angiogenic process involved in bone physiology. We studied the VEGF effect on osteoblast progenitor cells (Human Bone Marrow Stromal Cells: HBMSE) cultured alone or associated with endothelial cells (Human Umbilical Vein Endothelial Cells: HUVEC) in different co-culture models (co-culture with or without direct contact, conditioned medium), to determine the influence of VEGF on these cells and on their relationship. In agreement with other studies, we show that HBMSC express and synthesize VEGF, HUVEC conditioned medium has a proliferative effect on them, and early osteoblastic marker (Alkaline phosphatase activity) levels increase when these cells are co-cultured with HUVEC only in direct contact. However, unlike previous studies, we did not find that VEGF increased these processes. These results suggest that the intercommunication between endothelial cells and osteoblastic-like cells requires not only diffusible factors, but also involving cell membrane proteins.     

Effect of shear stress, statins and TNF-α on hemostatic genes in human endothelial cells

Atherosclerotic plaque formation and progression are dependent on local shear stress patterns and inflammatory cytokines. Statins effectively reduce the progression of atherosclerosis and the incidence of cardiovascular events. However, the benefit of statins cannot be explained by cholesterol reduction alone. This study, investigated the non-lipid lowering effects of simvastatin and rosuvastatin on endothelial anti- and prothrombotic genes under different biomechanical and inflammatory stress conditions. Endothelial cells responded in a similar way to simvastatin and rosuvastatin. However, they were more sensitive to simvastatin. The statins had anti-inflammatory properties counteracting the TNF-α effect on the hemostatic genes studied. There was no observed synergistic effect between shear stress and simvastatin. Simvastatin had a counteracting effect on t-PA and PAI-1 compared to TNF-α and shear stress. Simvastatin blocked the TNF-α suppressive effect on thrombomodulin and eNOS, irrespective of shear stress. The strong inductive effect of TNF-α on VCAM-1 was counteracted by simvastatin and shear stress in an additive dose-response dependent way.     

Genome-scale modeling of human metabolism – a systems biology approach

Altered metabolism is linked to the appearance of various human diseases and a better understanding of disease-associated metabolic changes may lead to the identification of novel prognostic biomarkers and the development of new therapies. Genome-scale metabolic models (GEMs) have been employed for studying human metabolism in a systematic manner, as well as for understanding complex human diseases. In the past decade, such metabolic models – one of the fundamental aspects of systems biology – have started contributing to the understanding of the mechanistic relationship between genotype and phenotype. In this review, we focus on the construction of the Human Metabolic Reaction database, the generation of healthy cell type- and cancer-specific GEMs using different procedures, and the potential applications of these developments in the study of human metabolism and in the identification of metabolic changes associated with various disorders. We further examine how in silico genome-scale reconstructions can be employed to simulate metabolic flux distributions and how high-throughput omics data can be analyzed in a context-dependent fashion. Insights yielded from this mechanistic modeling approach can be used for identifying new therapeutic agents and drug targets as well as for the discovery of novel biomarkers. Finally, recent advancements in genome-scale modeling and the future challenge of developing a model of whole-body metabolism are presented. The emergent contribution of GEMs to personalized and translational medicine is also discussed.     

Presence of an α-galactolipid on the cell surfaces of endothelial cells of human kidney

Summary The presence of an -galactolipid was investigated with a peroxidase-labelled lectin fromGriffonia simplicifolia (GSA-I) with specific binding for terminal -d-galactose residues. Normal kidney tissue was obtained from patients undergoing nephrectomy for renal neoplasms. For light microscopy, tissue was snap-frozen; 4 µm-thick sections were briefly fixed in paraformaldehyde and incubated with GSA (0.025 mg ml^–1). The peroxidase activity was developed with 3-amino-9-ethylcarbazole. Adjacent sections were stained at the same time after lipid extraction with 3:1 (v/v) chloroform/methanol. For electron microscopy, 0.2–0.5 mm-thick paraformaldehyde-fixed blocks, with or without lipid extraction, were stained with peroxidase-labelled GSA. The label was developed with diaminobenzidine and osmium tetroxide. Some structures, such as tubular epithelia, stained both in lipid-extracted and non-extracted tissues, suggesting that glycoproteins were most likely involved. In addition, tissue stained immediately after fixation showed GSA reactivity on endothelial cell surfaces of intertubular capillaries and larger vessels. In lipid-extracted tissues, however, tubular epithelium was still positive for GSA but endothelial cells failed to stain. These findings suggest that a glycolipid, bearing a terminal -galactose residue, is present on the endothelial cells in human kidney and possibly on tubular epithelia. Our data may explain the preferential storage of -galactolipid in endothelial cells of patients with Fabry's disease and other biological phenomena such asEscherichia coli adhesion.     

Effect of cigarette smoke exposure and structural modifications on the α-1 Antitrypsin interaction with caspases

α-1 Antitrypsin (A1AT) is a serpin with a major protective effect against cigarette smoke-induced emphysema development, and patients with mutations of the A1AT gene display a markedly increased risk for developing emphysema. We reported that A1AT protects lung endothelial cells from apoptosis and inhibits caspase-3 activity. It is not clear if cigarette smoking or A1AT mutations alter the caspase-3 inhibitory activity of A1AT and if this serpin alters the function of other caspases. We tested the hypothesis that the caspase-3 inhibitory activity of A1AT is impaired by cigarette smoking and that the A1AT RCL, the key antiprotease domain of the serpin, is required for its interaction with the caspase. We examined the caspase-3 inhibitory activity of human A1AT purified from plasma of actively smoking and nonsmoking individuals, either affected or unaffected with chronic obstructive pulmonary disease. We also tested the caspase inhibitory activity of two mutant forms of A1AT, the recombinant human piZZ and the RCL-deleted (RCL-null) A1AT forms. A1AT purified from the blood of active smokers exhibited marked attenuation in its caspase-3 inhibitory activity, independent of disease status. In vitro exposure of the normal (MM) form of A1AT to cigarette smoke extract reduced its ability to interact with caspase-3, measured by isothermal titration calorimetry, as did the deletion of the RCL, but not the ZZ point mutation. In cell-free assays A1AT was capable of inhibiting all executioner caspases, -3, -7 and especially -6, but not the initiator or inflammatory caspases. The inhibitory effect of A1AT against caspase-6 was tested in vivo, where overexpression of both human MM and ZZ-A1AT via adeno-associated virus transduction significantly protected against apoptosis and against airspace damage induced by intratracheal instillation of caspase-6 in mice. These data indicate a specific inhibitory effect of A1AT on executioner caspases, which is profoundly attenuated by active exposure to cigarette smoking and is dependent on the protein RCL, but is not affected by the PiZZ mutation.     

The presence of serotonin in cigarette smoke – a possible mechanistic link to 5-HT-induced airway inflammation

We previously reported the involvement of serotonin (5-HT) metabolism in cigarette smoke-induced oxidative stress in rat lung in vivo. Here, we report cigarette smoke as a source of serotonin (5-HT) to the airways and aim at investigating the effects of 5-HT on oxidative stress and inflammation in human bronchial epithelial cells (BEAS-2B). A 5-HT analog was identified to be present in aqueous phase cigarette smoke using the LC-MS/MS approach, which was later confirmed by a 5-HT enzyme-linked immune assay (EIA). Furthermore, exposure to 5-HT caused a time-dependent elevation of intracellular ROS level, which was blocked in the presence of apocynin (a NOX inhibitor). In support, the immunoblot analysis indicated that there was an increase in the expression of NOX2 time-dependently. 5-HT-induced elevation of IL-8 at both mRNA and protein levels was observed, which was inhibited by TEMPOL (a free radical scavenger), and inhibitors for p38 MAPK (SB203580) and ERK (U0126), in line with the time-dependent phosphorylation of p38 MAPK and ERK. In conclusion, our findings suggest that 5-HT presented in bronchial epithelium of smokers may be involved in cigarette smoke-induced oxidative stress and inflammation via activation of p38 MAPK and ERK pathway after the formation of free radicals.     

Effect of the three-dimensional organization of liver cells on the biogenesis of the γ-glutamyltransferase fraction pattern

Context Four gamma-glutamyltransferase (GGT) fractions with different molecular weights (big-, medium-, small- and free-GGT) are detectable in human plasma. Objective Verify if liver cells can release all four GGT fractions and if the spatial cell organization influences their release. Methods Hepatoma (HepG2) and melanoma (Me665/2/60) cells were cultured as monolayers or spheroids. GGT released in culture media was analysed by gel-filtration chromatography. Results HepG2 and Me665/2/60 monolayers released the b-GGT fraction, while significative levels of s-GGT and f-GGT were detectable only in media of HepG2-spheroids. Bile acids alone or in combination with papain promoted the conversion of b-GGT in s-GGT or f-GGT, respectively. Conclusions GGT is usually released as b-GGT, while s-GGT and f-GGT are likely to be produced in the liver extracellular environment by the combined action of bile acids and proteases.     

Effect of an epoxy derivative of 2′5′-trioligoadenylate on human neuroblastoma cells

We studied the effect of an epoxy derivative of dephosphorylated 2′,5′-trioligoadenylate (5′,5′ApApAepoxy) resistive to the action of cellular phosphodiesterase on cells of human neuroblastoma IMR 32 cultured in vitro. Twenty-two hours after the addition of 5·10⁻⁶ M 2′,5′ApApAepoxy to the culture medium, the number of cells decreased by 20% (P < 0.05), while the content of protein in these cells increased, on average, by 52% (P < 0.01), as compared with the control. The activities of Na⁺,K⁺-and Ca²⁺, Mg²⁺-ATPases in a microsomal fraction obtained from cells cultured in the presence of 2′, 5′ ApApAepoxy decreased by 50% (P < 0.001) as compared with those in the control cells. Our data indicate that 2′,5′ApApAepoxy possess antiproliferative activity. According to our findings, the antiproliferative effect of 2′,5′ ApApAepoxy can, to a great extent, be explained by the fact that this oligoadenylate derivative significantly modulates the activities of Na⁺,K⁺-and Ca²⁺,Mg²⁺-ATPases. Neirofiziologiya/Neurophysiology, Vol. 38, No. 2, pp. 97–102, March–April, 2006.     

Effect of purified human interferon-α on the expression of differentiation antigens and mitogen reactivity of cultured human thymic cells

Human thymic cells were cultured in vitro either alone or with the addition of a highly purified preparation of human interferon-α. Immunofluorescence techniques using a series of monoclonal antibodies showed that 2-day cultured thymocytes express a more mature phenotype (low HTA 1, high T3 and HLA-A,B,C) than normal, uncultured thymocytes. Interferon addition to the cultures results in a strong increment in the number of HLA⁺ cells and in the total amount of HLA expressed by the cultured cells. Experiments with purified cell populations showed that the cortical, immature, thymocyte was the target cell for interferon action. Phytohemagglutinin responses—but not interleukin 2 responses—were diminished after pretreatment of thymic cells with interferon. We suggest that interferon may favor a pathway of intrathymic differentiation phenotypically characterized by a high content of Class I HLA antigens.     

Effect of thapsigargin on Ca²+ fluxes and viability in human prostate cancer cells

Effect of the carcinogen thapsigargin on human prostate cancer cells is unclear. This study examined if thapsigargin altered basal [Ca2?](i) levels in suspended PC3 human prostate cancer cells by using fura-2 as a Ca2?-sensitive fluorescent probe. Thapsigargin at concentrations between 10?nM and 10 μM increased [Ca2?](i) in a concentration-dependent fashion. The Ca2? signal was reduced partly by removing extracellular Ca2? indicating that Ca2? entry and release both contributed to the [Ca2?](i) rise. This Ca2? influx was inhibited by suppression of phospholipase A2, but not by inhibition of store-operated Ca2? channels or by modulation of protein kinase C activity. In Ca2?-free medium, pretreatment with the endoplasmic reticulum Ca2? pump inhibitor 2,5-di-(t-butyl)-1,4-hydroquinone (BHQ) nearly abolished thapsigargin-induced Ca2? release. Conversely, pretreatment with thapsigargin greatly reduced BHQ-induced [Ca2?](i) rise, suggesting that thapsigargin released Ca2? from the endoplasmic reticulum. Inhibition of phospholipase C did not change thapsigargin-induced [Ca2?](i) rise. At concentrations of 1-10 μM, thapsigargin induced cell death that was partly reversed by chelation of Ca2? with BAPTA/AM. Annexin V/propidium iodide staining data suggest that apoptosis was partly responsible for thapsigargin-induced cell death. Together, in PC3 human prostate cancer cells, thapsigargin induced [Ca2?](i) rises by causing phospholipase C-independent Ca2? release from the endoplasmic reticulum and Ca2? influx via phospholipase A2-sensitive Ca2? channels. Thapsigargin also induced cell death via Ca2?-dependent pathways and Ca2?-independent apoptotic pathways.     

Effect of aneurysm on biomechanical properties of “radially-oriented” collagen fibers in human ascending thoracic aortic media

We recently reported a mechanistic model to link micro-architectural information to the delamination strength (S_d) of human ascending thoracic aorta (ATA). That analysis demonstrated that the number density (N) and failure energy (U_f) of the radially-oriented collagen fibers contribute to the S_d of both aneurysmal (ATAA) and non-aneurysmal (CTRL-ATA) aortic tissue. Among the set of ATAA samples, we studied specimens from patients displaying bicuspid (BAV) and tricuspid aortic valve (TAV) morphologic phenotypes. Results from our prior work were based on the assumption that the U_f was independent of dissection direction. In the current study, we excluded that assumption and hypothesized that U_f correlates with the S_d of ATAA. To test the hypothesis, we used previously-reported experimentally-determined S_d measurements and N of radially-oriented collagen fibers as input in our validated mechanistic model to calculate U_f for BAV-ATAA, TAV-ATAA and CTRL-ATA tissue specimens. The results of our analysis revealed that U_f is significantly lower for both BAV-ATAA and TAV-ATAA compared to CTRL-ATA cases, and does not differ between BAV-ATAA and TAV-ATAA. Furthermore, we found that U_f is consistent between circumferential-radial and longitudinal-radial planes in either of BAV-ATAA, TAV-ATAA or CTRL-ATA specimens. These findings employ a novel mechanistic model to increase our understanding of the putative interrelationship between biomechanical properties, extracellular matrix biology, and failure energy of aortic dissection.     

Investigation on the role of nsSNPs in HNPCC genes – a bioinformatics approach

Background  

A central focus of cancer genetics is the study of mutations that are causally implicated in tumorigenesis. The identification of such causal mutations not only provides insight into cancer biology but also presents anticancer therapeutic targets and diagnostic markers. Missense mutations are nucleotide substitutions that change an amino acid in a protein, the deleterious effects of these mutations are commonly attributed to their impact on primary amino acid sequence and protein structure.     

The stimulation of arginine transport by TNFα in human endothelial cells depends on NF-κB activation

In human saphenous vein endothelial cells (HSVECs), tumor necrosis factor-α (TNFα) and bacterial lipopolysaccharide (LPS), but neither interferon γ (IFNγ) nor interleukin 1β (IL-1β), stimulate arginine transport. The effects of TNFα and LPS are due solely to the enhancement of system y⁺ activity, whereas system y⁺L is substantially unaffected. TNFα  causes an increased expression of SLC7A2/CAT-2B gene while SLC7A1/CAT-1 expression is not altered by the cytokine. The suppression of PKC-dependent transduction pathways, obtained with the inhibitor chelerytrhine, the inhibitor peptide of PKCζ isoform, or chronic exposure to phorbol esters, does not prevent TNFα effect on arginine transport. Likewise, ERK, JNK, and p38 MAP kinases are not involved in the cytokine effect, since arginine transport stimulation is unaffected by their specific inhibitors. On the contrary, inhibitors of NF-κB pathway hinder the increase in CAT2B mRNA and the stimulation of arginine uptake. These results indicate that in human endothelial cells the activation of NF-κB pathway mediates the TNFα effects on arginine transport.     

Effect of dephosphorylated 2′,5′-trioligoadenylate on the entry of sodium ions into human neuroblastoma cells

Using a radioisotope technique, we studied the effect of dephosphorylated 2′,5′-trioligoadenylate (2′,5′ ApApA) on the entry of sodium ions into cultured human neuroblastoma cells (IMR 32 strain). Short-term (nearly 1 h) action of 2′,5′ ApApA did not influence the entry of sodium ions through voltage-operated sodium channels in the absence of neurotoxins modulating the characteristics of these channels (toxin of a scorpion, Leiurus quinquestriatus, + veratrine). At the same time, 2′,5′ ApApA weakened in a dose-dependent manner the entry of sodium ions through sodium channels opened upon the action of the above neurotoxins. In cells cultured for 22 h in a medium containing 5 · 10⁻⁶ M 2′,5′ ApApA, the entry of sodium ions in the absence of neurotoxins was 25% greater, while in the presence of neurotoxins it was 24% smaller than that in the control cells. Tetrodotoxin (TTX, 4 · 10⁻⁷ M) blocked completely sodium entry through sodium channels in cells cultured in the absence of 2′,5′ ApApA, while in cells cultured in the presence of this adenylate TTX decreased the entry by 64%. It is hypothesized that long-lasting action of 2′,5′ ApApA results in the appearance of voltage-operated TTX-insensitive sodium channels in the plasma membrane of IMR 32 cells. Our data show that 2′,5′ ApApA is capable of modulating to a considerable extent the functioning of mechanisms controlling transport of sodium ions in cells of human neuroblastoma cells of the IMR 32 strain. Neirofiziologiya/Neurophysiology, Vol. 40, No. 1, pp. 3–8, January–February, 2008.     

Effect of human cell malignancy on activity of DNA polymerase ι

An increased level of mutagenesis, partially caused by imbalanced activities of error prone DNA polymerases, is a key symptom of cell malignancy. To clarify the possible role of incorrect DNA polymerase ι (Pol ι) function in increased frequency of mutations in mammalian cells, the activity of this enzyme in extracts of cells of different mouse organs and human eye (melanoma) and eyelid (basal-cell skin carcinoma) tumor cells was studied. Both Mg²⁺, considered as the main activator of the enzyme reaction of in vivo DNA replication, and Mn²⁺, that activates homogeneous Pol ι preparations in experiments in vitro more efficiently compared to all other bivalent cations, were used as cofactors of the DNA polymerase reaction in these experiments. In the presence of Mg²⁺, the enzyme was active only in cell extracts of mouse testicles and brain, whereas in the presence of Mn²⁺ the activity of Pol ι was found in all studied normal mouse organs. It was found that in cell extracts of both types of malignant tumors (basal-cell carcinoma and melanoma) Pol ι activity was observed in the presence of either Mn²⁺ or Mg²⁺. Manganese ions activated Pol ι in both cases, though to a different extent. In the presence of Mn²⁺ the Pol ι activity in the basal-cell carcinoma exceeded 2.5-fold that in control cells (benign tumors from the same eyelid region). In extracts of melanoma cells in the presence of either cation, the level of the enzyme activity was approximately equal to that in extracts of cells of surrounding tumor-free tissues as well as in eyes removed after traumas. The distinctive feature of tissue malignancy (in basal-cell carcinoma and in melanoma) was the change in DNA synthesis revealed as Mn²⁺-activated continuation of DNA synthesis after incorrect incorporation of dG opposite dT in the template by Pol ι. Among cell extracts of different normal mouse organs, only those of testicles exhibited a similar feature. This similarity can be explained by cell division blocking that occurs in all normal cells except in testicles and in malignant cells.     

Designing and optimization of novel human LMTK3 inhibitors against breast cancer – a computational approach

Estrogen receptor-α (ERα) is expressed more in patients with breast cancer and its level correlated with endocrine resistance. LMTK3 is reported as breast cancer target with regulation of estrogen receptor-α (ERα) through phosphorylation. In this computational study, structure-based inhibitor screening was performed on human LMTK3 using ZINC database. ATP-binding cavity with critical residues involved in the LMTK3 phosphorylation was used as target site for the screening. From the large ligand library, the best compounds were screen with three-phase virtual screening methods in Dockblaster, AutoDock Vina and AutoDock, respectively. The evaluation of ligands was carried out by binding energy and weak interactions, such as hydrogen bond interactions and hydrophobic contacts, in the target site that favors LMTK3 inhibition. Top compounds were found to be more effective in druglikeness activity by ADME prediction. The stability and binding affinity of ligand complexes were optimized by trajectory analysis such as RMSD, Rg, SASA and interhydrogen bonds from molecular dynamics simulations. The behavior of protein motion after ligand binding was illustrated by eigenvectors from principal component analysis (PCA). In addition, binding free energy of the LMTK3–ligand complexes were calculated by MM/PBSA methods and results supported the strong binding in dynamic system. Thus, the computational studies illustrated the structural insights on LMTK3 inhibition mechanism by ligands ZINC04670539, ZINC05607079 and ZINC04344028, also proposed as potent lead candidates. Our findings step towards developing novel LMTK3 inhibitors and identified lead candidates can be future breast cancer drugs with further experimental studies.     

Docosahexaenoic acid attenuates VCAM-1 expression and NF-κB activation in TNF-α-treated human aortic endothelial cells

This study was conducted to test the hypothesis that n-3 polyunsaturated fatty acids are able to down-regulate expression of adhesion molecules and nuclear factor-κB (NF-κB) activation in vascular endothelial cells, in addition to reducing atherosclerotic lesions in vivo. We report here that docosahexaenoic acid (DHA) reduces atherosclerotic lesions in the aortic arteries of apolipoprotein E knockout (apoE^-/-) mice. Consistent with the observation in animal study, DHA inhibited THP-1 cell adhesion to tumor necrosis factor α (TNF-α)-activated human aortic endothelial cells (HAECs). Expression of vascular cell adhesion molecule 1 (VCAM-1) and intercellular adhesion molecule 1 (ICAM-1) on the cell surface of HAECs was determined by cell-surface enzyme-linked immunosorbent assay. DHA and eicosapentaenoic acid decreased VCAM-1 expression in a dose-dependent manner in TNF-α treated HAECs, while cis-linoleic acid and arachidonic acid did not have any significant effect on either VCAM-1 or ICAM-1 expression. Moreover, DHA significantly reduced VCAM-1 protein expression in the cell lysates of TNF-α-treated HAECs, as determined by Western blot analysis. In line with NF-κB signaling pathway, DHA suppressed the TNF-α-activated IκBα phosphorylation and degradation as well as IκB kinase-β phosphorylation. Subsequently, translocation of the NF-κB (p50/p65) and AP-1 (c-Fos/c-Jun) subunits was down-regulated by DHA in the nucleus of HAECs. These results suggest that DHA negatively regulates TNF-α-induced VCAM-1 expression through attenuation of NF-κB signaling pathway and AP-1 activation. This study provides evidence that DHA may contribute to the prevention of atherosclerosis and inflammatory diseases in vivo.     

The impact of HPV infection on human glycogen and lipid metabolism – a review

Reinterpretation of the Wartburg effect leads to understanding aerobic glycolysis as a process that provides considerable amount of molecular precursors for the production of lipids, nucleotides and amino acids that are necessary for continuous growth and rapid proliferation characteristic for cancer cells.Human papilloma virus (HPV) is a number one cause of cervical carcinoma with 99% of the cervical cancer patients being HPV positive. This tight link between HPV and cancer raises the question if and how HPV impact cells to reprogram their metabolism? Focusing on early phase proteins E1, E2, E5, E6 and E7 we demonstrate that HPV activates plethora of metabolic pathways and directly influences enzymes of the glycolysis pathway to promote the Warburg effect by increasing glucose uptake, activating glycolysis and pentose phosphate pathway, increasing the level of lactate dehydrogenase A synthesis and inhibiting β-oxidation. Our considerations lead to conclusion that HPV is substantially involved in metabolic cell reprogramming toward neoplastic phenotype and its metabolic activity is the fundamental reason of its oncogenicity.     

Effect of protocatechuic acid from Alpinia oxyphylla on proliferation of human adipose tissue-derived stromal cells in vitro

The effect of protocatechuic acid (PCA) from Alpinia oxyphylla and catapol from Rehmannia on the proliferation capacity of human adipose tissue-derived stromal cells (hADSCs) was investigated in vitro. Cell counts showed that treatment of hADSCs with PCA for 48 h increased the cell number in a dose-dependent manner, while no obvious effect of catapol on the proliferation of hADSCs was observed. In addition, the cell number of hADSCs treated by 1.5 mM PCA increased in a time-dependent manner. The flow cytometric analysis of DNA content demonstrated the cell cycle progress from the G0/G1 phase to the S phase. Western blot analysis revealed the elevated expression of cyclin D1 in hADSCs induced by PCA treatment. Cyclin D1-siRNA transfection significantly inhibit the promotion of cell proliferation by PCA. Furthermore, the flow cytometric analysis of the cell surface antigens and the multidifferential potential tests of PCA-treated hADSCs showed that the cells retained their functional characteristics of multipotential mesenchymal progenitors. It is concluded that PCA can effectively up-regulate the proliferation of hADSCs.