Jorge Aquino
UNAM Universidad Nacional Autónoma de México, Hematology, Graduate Student
Mesenchymal stem cells (MSCs) are multipotent cells with self-renewal capacity which are present in diverse tissues. Recently, significant progresses have been made in the field of MSCs because of its therapeutic potential in regenerative... more
Mesenchymal stem cells (MSCs) are multipotent cells with self-renewal capacity which are present in diverse tissues. Recently, significant progresses have been made in the field of MSCs because of its therapeutic potential in regenerative medicine. MSCs selectively migrate toward sites of damage and remodeling, and have the ability to evade the immune system and to promote tissue repair through the production of a number of growth factors and cytokines. Many pre-clinical and clinical studies have been carried out to study its therapeutic effect in liver cirrhosis with promising results. In addition, experimental studies showed that this therapeutic effect can be improved by engineering MSCs to produce therapeutic genes. In this work, the role of MSCs in regenerative medicine and its clinical and pre-clinical applications are reviewed, with an emphasis on its potential as vehicles for therapeutic genes.
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Research Interests: Genetics, Stem Cells, Cell Adhesion, Transcription Factors, Gene expression, and 18 moreCerebellum, Mice, Animals, Proteins, Transcription Factor, Clinical Sciences, Pituitary Gland, mRna expression levels, Embryonic Development, Retinoic Acid, Protein Expression, Neural Tube Defects, DNA binding proteins, Differential expression, Brain stem, Olfactory Epithelium, Mesencephalon, and Signaling pathway
In this work we analyzed variations in the expression of MBPs and P0 in ligated sciatic nerves of young and adult rats at 3, 7, and 14 days postligation (PL), by immunohistochemistry and SDS-PAGE of isolated myelin. A protein... more
In this work we analyzed variations in the expression of MBPs and P0 in ligated sciatic nerves of young and adult rats at 3, 7, and 14 days postligation (PL), by immunohistochemistry and SDS-PAGE of isolated myelin. A protein redistribution was seen in the distal stump of ligated nerves with the appearance of immunoreactive clusters. Using the KS400 image analyzer, immunostained area values were obtained from the different nerves dissected. In adult rats, there was an increase of the immunostained area for MBP from 3 to 7 days PL, coincident with a reorganization of the marker in clusters, followed by a marked decrease at 14 days. P0 immunolabeling gave similar results without, however, a decrease of the immunostained area at the longer survival time tested. Young animals showed an acceleration in the process of protein redistribution and digestion within ligated nerves, which followed a similar pattern as that of adult animals. Analysis by electrophoresis showed a marked decrease in P0 and MBP at 7 days PL in young rats and 14 days PL in adult rats. The functional significance of protein clustering within myelin in injured nerves deserves further analysis.
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Surgical resection is the only curative option for patients with gastrointestinal carcinomas. Unfortunately, the majority of patients are diagnosed in advanced stages when surgery is not possible. Moreover, the incidence and mortality for... more
Surgical resection is the only curative option for patients with gastrointestinal carcinomas. Unfortunately, the majority of patients are diagnosed in advanced stages when surgery is not possible. Moreover, the incidence and mortality for certain type of tumors such as hepatocellular carcinoma or pancreatic cancer are steadily increasing worldwide. In spite of the advances in the development of molecular targeted therapies for cancer, the impact on patient survival has been rather limited. It is unlikely that individual agents would be ultimately successful as monotherapy. There is a growing area of research focused on the combination of classical chemotherapy (e.g. cyclophosphamide, gemcitabine, paclitaxel and doxorubicin) with radiotherapy and/or gene therapy strategies. Combined approaches seem to be required due to multiple resistance mechanisms that tumors utilize to limit the activity of chemotherapeutic agents (e.g. the occurrence of multidrug resistance or epigenetic alterations), evade immune responses (e.g. induction of regulatory T cells or myeloid-derived suppressor cells) and to generate resistance against anti-angiogenesis or to radiotherapy by, for example, the induction of hypoxia-inducible factor 1. In addition, new studies suggest that combination of low dose of conventional chemotherapy and gene therapy could allow the development of synergic mechanisms able to achieve significant therapeutic effects against diverse tumors. Although cancer gene therapy is not yet available in clinical practice, advances being recently made look promising, especially when it was applied in combination with standard chemo- or radiotherapy protocols.
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Hyaluronan modulates cancer progression by multiple mechanisms; nevertheless, its effects remain controversial. In this work, low molecular weight (LMW) hyaluronan but not high molecular weight (HMW) was found to significantly reduce... more
Hyaluronan modulates cancer progression by multiple mechanisms; nevertheless, its effects remain controversial. In this work, low molecular weight (LMW) hyaluronan but not high molecular weight (HMW) was found to significantly reduce colorectal carcinoma (CRC) growth in vitro and in vivo. Both survival and proliferation of CT26 tumor cells were affected by treatment with low doses of LMW HA, with involvement of Akt signaling mechanisms. We show for the first time that splenocytes isolated from LMW HA-treated animals present significantly higher proliferative capacity upon stimulation with dendritic cells (DCs) pulsed with tumor lysate. Consistently, expression of MHC class II and costimulatory molecules were increased in DCs isolated from the spleen of LMW HA-treated mice. Besides, increased tumor infiltrating lymphocytes was observed in animals treated with LMW HA. Our results suggest that LMW HA in a model of CRC triggers an activation of immune system, which is likely involved in the observed tumor growth inhibition. LMW HA is suggested as a candidate molecule for therapeutic adjuvant treatments in CRC immunotherapy.
Research Interests: Immune response, Flow Cytometry, Immunohistochemistry, Apoptosis, Dendritic Cells, and 16 moreLow Dose, Mice, Animals, Male, Dendritic cell, MHC class II, Hyaluronic Acid, Immune system, Molecular weight, Cell Proliferation, Tumor Growth, Low molecular weight, Bone Marrow Cells, Adenocarcinoma, Colorectal Neoplasms, and High Molecular Weight
During the last two decades, a number of immunotherapy-based strategies for advanced gastrointestinal carcinomas (GICs) has given promising results, not only at preclinical stage but also in the clinic. 1 However, immunotherapeutic... more
During the last two decades, a number of immunotherapy-based strategies for advanced gastrointestinal carcinomas (GICs) has given promising results, not only at preclinical stage but also in the clinic. 1 However, immunotherapeutic approaches have to face an important obstacle: the ability of tumor cells to evade immune attack. 2 Several immunosuppres-sive mechanisms elicited by cancer cells have been identified in animal models and in patients including: 1 loss of MHC Class I molecules from the surface of tumor cells, 2 increased oxidative stress and 3 recruit-ment of myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs). A correlation between increased levels of these immunosuppressive cell populations and poor prognosis has been observed in many types of cancer. 3 Increasing evidence suggests that immune responses are involved in the con-trol of cancer and that the immune system can be manipulated in different ways to recognize and fight cancer cells. The sys-te...
Mesenchymal stem/stromal cells (MSCs) are progenitors which share plastic-adherence capacity and cell surface markers but have different properties according to their cell and tissue sources and to culture conditions applied. Many recent... more
Mesenchymal stem/stromal cells (MSCs) are progenitors which share plastic-adherence capacity and cell surface markers but have different properties according to their cell and tissue sources and to culture conditions applied. Many recent publications suggest that MSCs can differentiate into hepatic-like cells, which can be a consequence of either a positive selection of rare in vivo pluripotent cells or of the original plasticity of some cells contributing to MSC cultures. A possible role of MSCs in hereditary transmission of obesity and/or diabetes as well as properties of MSCs regarding immunomodulation, cell fusion and exosome release capacities are discussed according to recent literature. Limitations in methods used to track MSCs in vivo especially in the context of liver cirrhosis are addressed as well as strategies explored to enhance their migratory, survival and proliferation properties, which are known to be relevant for their future clinical use. Current knowledge regardi...
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Surgical resection is the only curative option for patients with gastrointestinal carcinomas. Unfortunately, the majority of patients are diagnosed in advanced stages when surgery is not possible. Moreover, the incidence and mortality for... more
Surgical resection is the only curative option for patients with gastrointestinal carcinomas. Unfortunately, the majority of patients are diagnosed in advanced stages when surgery is not possible. Moreover, the incidence and mortality for certain type of tumors such as hepatocellular carcinoma or pancreatic cancer are steadily increasing worldwide. In spite of the advances in the development of molecular targeted therapies for cancer, the impact on patient survival has been rather limited. It is unlikely that individual agents would be ultimately successful as monotherapy. There is a growing area of research focused on the combination of classical chemotherapy (e.g. cyclophosphamide, gemcitabine, paclitaxel and doxorubicin) with radiotherapy and/or gene therapy strategies. Combined approaches seem to be required due to multiple resistance mechanisms that tumors utilize to limit the activity of chemotherapeutic agents (e.g. the occurrence of multidrug resistance or epigenetic alterations), evade immune responses (e.g. induction of regulatory T cells or myeloid-derived suppressor cells) and to generate resistance against anti-angiogenesis or to radiotherapy by, for example, the induction of hypoxia-inducible factor 1. In addition, new studies suggest that combination of low dose of conventional chemotherapy and gene therapy could allow the development of synergic mechanisms able to achieve significant therapeutic effects against diverse tumors. Although cancer gene therapy is not yet available in clinical practice, advances being recently made look promising, especially when it was applied in combination with standard chemo- or radiotherapy protocols.
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In this work we analyzed variations in the expression of MBPs and P0 in ligated sciatic nerves of young and adult rats at 3, 7, and 14 days postligation (PL), by immunohistochemistry and SDS-PAGE of isolated myelin. A protein... more
In this work we analyzed variations in the expression of MBPs and P0 in ligated sciatic nerves of young and adult rats at 3, 7, and 14 days postligation (PL), by immunohistochemistry and SDS-PAGE of isolated myelin. A protein redistribution was seen in the distal stump of ligated nerves with the appearance of immunoreactive clusters. Using the KS400 image analyzer, immunostained area values were obtained from the different nerves dissected. In adult rats, there was an increase of the immunostained area for MBP from 3 to 7 days PL, coincident with a reorganization of the marker in clusters, followed by a marked decrease at 14 days. P0 immunolabeling gave similar results without, however, a decrease of the immunostained area at the longer survival time tested. Young animals showed an acceleration in the process of protein redistribution and digestion within ligated nerves, which followed a similar pattern as that of adult animals. Analysis by electrophoresis showed a marked decrease i...
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Hepatocellular carcinoma (HCC) is the third cause of cancer-related death worldwide. Unfortunately, the incidence and mortality associated with HCC are increasing. Therefore, new therapeutic strategies are urgently needed and the use of... more
Hepatocellular carcinoma (HCC) is the third cause of cancer-related death worldwide. Unfortunately, the incidence and mortality associated with HCC are increasing. Therefore, new therapeutic strategies are urgently needed and the use of mesenchymal stromal cells (MSCs) as carrier of therapeutic genes is emerging as a promising option. Different sources of MSCs are being studied for cell therapy and bone marrow-derived cells are the most extensively explored; however, birth associated-tissues represent a very promising source. The aim of this work was to compare thein vitroandin vivomigration capacity between bone marrow MSCs (BM-MSCs) and human umbilical cord perivascular cells (HUCPVCs) towards HCC. We observed that HUCPVCs presented higherin vitroandin vivomigration towards factors released by HCC. The expression of autocrine motility factor (AMF) receptor, genes related with the availability of the receptor on the cell surface (caveolin-1 and -2) and metalloproteinase 3, induced ...
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Research Interests: Immunology, Informed Consent, Comparative Study, Hepatitis C, Medical History, and 16 moreProspective studies, Humans, Female, Male, Polymerase Chain Reaction, Self Disclosure, Clinical Sciences, Prevalence, Middle Aged, Questionnaires, Adult, Blood Donors, Medical Records, Transfusion, Predictive value of tests, and Immunoblotting
Hepatocellular carcinoma (HCC) is the fifth most common cancer and the third cause of cancer-related death. Fibrogenesis is an active process characterized by the production of several proinflammatory cytokines, chemokines and growth... more
Hepatocellular carcinoma (HCC) is the fifth most common cancer and the third cause of cancer-related death. Fibrogenesis is an active process characterized by the production of several proinflammatory cytokines, chemokines and growth factors. It involves the activation of hepatic stellate cells (HSCs) which accumulate at the site of injury and are the main source of the extracellular matrix deposits. There are no curative treatments for advanced HCC, thus, new therapies are urgently needed. Mesenchymal stromal cells (MSCs) have the ability to migrate to sites of injury or to remodeling tissues after in vivo administration; however, in several cancer models they demonstrated limited efficacy to eradicate experimental tumors partially due to poor engraftment. Thus, the aim of this work was to analyze the capacity of human MSCs (hMSCs) to migrate and anchor to HCC tumors. We observed that HCC and HSCs, but not nontumoral stroma, produce factors that induce hMSC migration in vitro. Conditioned media (CM) generated from established HCC cell lines were found to induce higher levels of hMSC migration than CM derived from fresh patient tumor samples. In addition, after exposure to CM from HCC cells or HSCs, hMSCs demonstrated adhesion and invasion capability to endothelial cells, type IV collagen and fibrinogen. Consistently, these cells were found to increase metalloproteinase-2 activity. In vivo studies with subcutaneous and orthotopic HCC models indicated that intravenously infused hMSCs migrated to lungs, spleen and liver. Seven days post-hMSC infusion cells were located also in the tumor in both models, but the signal intensity was significantly higher in orthotopic than in subcutaneous model. Interestingly, when orthotopic HCC tumors where established in noncirrhotic or cirrhotic livers, the amount of hMSCs localized in the liver was higher in comparison with healthy animals. A very low signal was found in lungs and spleens, indicating that liver tumors are able to recruit them at high efficiency. Taken together our results indicate that HCC and HSC cells produce factors that efficiently induce hMSC migration toward tumor microenvironment in vitro and in vivo and make MSCs candidates for cell-based therapeutic strategies to hepatocellular carcinoma associated with fibrosis.
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Immunotherapy-based strategies for gastrointestinal carcinomas (GIC) have been exploited so far, but these approaches have to face strong mechanisms of immune escape induced by tumours. We previously demonstrated that sub-therapeutic... more
Immunotherapy-based strategies for gastrointestinal carcinomas (GIC) have been exploited so far, but these approaches have to face strong mechanisms of immune escape induced by tumours. We previously demonstrated that sub-therapeutic doses of an adenovirus expressing IL-12 genes (AdIL-12) mediated a potent antitumour effect against subcutaneous (s.c.) colorectal carcinomas (CRC) in mice pre-treated with low doses of cyclophosphamide (Cy). In our study we used this combination to assess its impact on the immunosuppressive microenvironment. In s.c. CRC model we demonstrated that non-responder mice failed to decrease Tregs in tumour, spleen and peripheral blood. Reconstitution of Tregs into tumour-bearing mice treated with combined therapy abolished the antitumoural effect. In addition, Cy + AdIL-12 modified Tregs functionality by inhibiting the in vitro secretion of IL-10 and TGF-β and their ability to inhibit dendritic cells activation. Combined treatment decreased the number of myeloid-derived suppressor cells (MDSCs) in comparison to non-treated mice and, interestingly, administration of Tregs restored splenic MDSCs population. Furthermore, combined therapy potently generated specific cytotoxic IFN-γ-secreting CD4+ T cells able to eradicate established CRC tumours after adoptive transfer. Finally, we evaluated the combination on disseminated CRC and pancreatic carcinoma (PC). Cy + AdIL-12 were able to eradicate liver metastatic CRC (47%) and PC tumour nodules (40%) and to prolong animal survival. The results of this study support the hypothesis that Cy + AdIL-12 might be a valid immunotherapeutic strategy for advanced GIC.
Research Interests: Dendritic Cells, Molecular Oncology, Humans, Low Dose, Mice, and 17 moreImmunity, Animals, Gene transfer techniques, Immunosuppression, Dendritic cell, Phenotype, Transforming Growth Factor Beta, Combination drug therapy, Myeloid Derived Suppressor Cells, Cyclophosphamide, Antineoplastic Agents, Gene Transfer, Interleukin, Adoptive Transfer, Interferon gamma, Combined Modality Therapy, and Combination Therapy
Research Interests: Genetics, Physiology, Cellular Biology, Metabolism, Embryology, and 28 moreImmunohistochemistry, Transcription Factors, Medicine, Sequence Analysis, Biological Sciences, DNA, Molecular and cellular biology, Neural Crest, Mice, Cytology, Animals, Polymerase Chain Reaction, Central Nervous System, Transcription Factor, Genes, Dorsal root ganglia, Time Factors, Motor Function, Reporter, Body Weight, Rotation, Uncoupling Protein, Blood Vessel, Gene Expression Regulation, High fat diet, Motor activity, Body Weight Gain, and Tissue distribution
Hepatocyte apoptosis, the hallmark of non-alcoholic steatohepatitis (NASH) contributes to liver injury and fibrosis. Although, both the intrinsic and extrinsic apoptotic pathways are involved in the pathogenesis of NASH, the final common... more
Hepatocyte apoptosis, the hallmark of non-alcoholic steatohepatitis (NASH) contributes to liver injury and fibrosis. Although, both the intrinsic and extrinsic apoptotic pathways are involved in the pathogenesis of NASH, the final common step of apoptosis is executed by a family of cysteine-proteases termed caspases. Thus, our aim was to ascertain if administration of Emricasan, a pan-caspase inhibitor, ameliorates liver injury and fibrosis in a murine model of NASH. C57/BL6J-mice were fed regular chow or high fat diet (HFD) for 20 weeks. All mice were treated with vehicle or Emricasan. Mice fed a HFD diet demonstrate a five-fold increase in hepatocyte apoptosis by the TUNEL assay and a 1.5-fold and 1.3-fold increase in caspase-3 and-8 activities respectively; this increase in apoptosis was substantially attenuated in mice fed a HFD treated with Emricasan (HFD-Em). Likewise, liver injury and inflammation were reduced in mice fed HFD-Em as compare to HFD by measuring serum aspartate aminotransferase and alanine aminotransferase levels, NAS histological score and IL 1-β, TNF-α, monocyte chemoattractant protein (MCP-1) and C-X-C chemokine ligand-2 (CXCL2) quantitative reverse-transcription polymerase chain reaction (qPCR). These differences could not be attributed to differences in hepatic steatosis as liver triglycerides content were similar in both HFD groups. Hepatic fibrosis was reduced by Emricasan in HFD animals by decreasing αSMA (a marker for hepatic stellate cell activation), fibrosis score, Sirius red staining, hydroxyproline liver content and profibrogenic cytokines by qPCR. In conclusion, these data demonstrate that in a murine model of NASH, liver injury and fibrosis are suppressed by inhibiting hepatocytes apoptosis and suggests that Emricasan may be an attractive antifibrotic therapy in NASH.
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Mesenchymal stromal cells (MSCs) are more often obtained from adult and extraembryonic tissues, with the latter sources being likely better from a therapeutic perspective. MSCs show tropism towards inflamed or tumourigenic sites.... more
Mesenchymal stromal cells (MSCs) are more often obtained from adult and extraembryonic tissues, with the latter sources being likely better from a therapeutic perspective. MSCs show tropism towards inflamed or tumourigenic sites. Mechanisms involved in MSC recruitment into tumours are comprehensively analysed, including chemoattractant signalling axes, endothelial adhesion and transmigration. In addition, signals derived from hepatocellular carcinoma (HCC) tumour microenvironment and their influence in MSC tropism and tumour recruitment are dissected, as well as the present controversy regarding their influence on tumour growth and/or metastasis. Finally, evidences available on the use of MSCs and other selected progenitor/stem cells as vehicles of antitumourigenic genes are discussed. A better knowledge of the mechanisms involved in progenitor/stem cell recruitment to HCC tumours is proposed in order to enhance their tumour targeting which may result in improvements in cell-based gene therapy strategies.
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Research Interests: Immune response, Clinical Trial, Cytokines, Dendritic Cells, Cancer Vaccines, and 13 moreBiological Sciences, Humans, Liver, Biomedical science, Animals, Immunotherapy, Monoclonal Antibodies, Animal Model, Immune system, Tumor Progression, Liver Tumor, Clinical Trials as Topic, and Combined Modality Therapy
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Research Interests: Genetics, Stem Cells, Cell Adhesion, Transcription Factors, Gene expression, and 18 moreCerebellum, Mice, Animals, Proteins, Transcription Factor, Clinical Sciences, Pituitary Gland, mRna expression levels, Embryonic Development, Retinoic Acid, Protein Expression, Neural Tube Defects, DNA binding proteins, Differential expression, Brain stem, Olfactory Epithelium, Mesencephalon, and Signaling pathway
Peripheral sensory neurons are derived from two distinct structures, the ectodermal placodes and the neural crest. Here, we establish the forkhead family transcription factor Foxs1 as an early sensory neuronal marker. Early embryonic... more
Peripheral sensory neurons are derived from two distinct structures, the ectodermal placodes and the neural crest. Here, we establish the forkhead family transcription factor Foxs1 as an early sensory neuronal marker. Early embryonic Foxs1 expression was present in all the sensory nervous system regardless of cellular origin, but was not found in other placode and neural crest-derived cell types. Foxs1 expression was turned on in the sensory neuron precursors of the trunk. Consistently, expression of Sox10, that is present in undifferentiated multipotent neural crest cells (NCCs), was mutually exclusive to Foxs1. Acquirement of Foxs1 expression was used to study the emergence of the dorsal root ganglion (DRG) sensory neurons. Migrating pioneering Foxs1 expressing NCCs were found at the anterior dorsal somitic lip at the 18-somite stage. These cells showed limited proliferation and migrated to form a cluster in the ventral aspect of the coalescing ganglion, surrounded by Foxs1(-)/Sox10(+) migrating NCCs retaining a high rate of proliferation. Sensory neurogenesis of the Foxs1(-)/Sox10(+) precursors occurred within the condensed DRG starting with neurogenin-1 (Ngn1) and Brn3a expression. These data define a sequential emergence of neuronal precursors of the sensory nervous system with different molecular characteristics, starting during migration and continuing well after DRG condensation.
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Hyaluronan modulates cancer progression by multiple mechanisms; nevertheless, its effects remain controversial. In this work, low molecular weight (LMW) hyaluronan but not high molecular weight (HMW) was found to significantly reduce... more
Hyaluronan modulates cancer progression by multiple mechanisms; nevertheless, its effects remain controversial. In this work, low molecular weight (LMW) hyaluronan but not high molecular weight (HMW) was found to significantly reduce colorectal carcinoma (CRC) growth in vitro and in vivo. Both survival and proliferation of CT26 tumor cells were affected by treatment with low doses of LMW HA, with involvement of Akt signaling mechanisms. We show for the first time that splenocytes isolated from LMW HA-treated animals present significantly higher proliferative capacity upon stimulation with dendritic cells (DCs) pulsed with tumor lysate. Consistently, expression of MHC class II and costimulatory molecules were increased in DCs isolated from the spleen of LMW HA-treated mice. Besides, increased tumor infiltrating lymphocytes was observed in animals treated with LMW HA. Our results suggest that LMW HA in a model of CRC triggers an activation of immune system, which is likely involved in the observed tumor growth inhibition. LMW HA is suggested as a candidate molecule for therapeutic adjuvant treatments in CRC immunotherapy.
Research Interests: Immune response, Flow Cytometry, Immunohistochemistry, Apoptosis, Dendritic Cells, and 16 moreLow Dose, Mice, Animals, Male, Dendritic cell, MHC class II, Hyaluronic Acid, Immune system, Molecular weight, Cell Proliferation, Tumor Growth, Low molecular weight, Bone Marrow Cells, Adenocarcinoma, Colorectal Neoplasms, and High Molecular Weight
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Research Interests: Cognitive Science, Brain, Neural Crest, Mice, Animals, and 4 moreRats, Neural Stem Cells, Neurosciences, and Brain stem
Research Interests: Cognitive Science, Image Analysis, Immunohistochemistry, Treatment Outcome, Cytoskeleton, and 19 moreBrain, Animals, Transferrin, Microtubules, Neurotoxins, Colchicine, Rats, Blood Flow, Degeneration, Tubulin, Sciatic Nerve, Wistar Rats, Axons, Neurosciences, Nerve Injury, Neuroprotective Agents, Apoproteins, Myelin Sheath, and Axonal transport
Liver fibrosis is an active process that involves changes in cell-cell and cell-extracellular matrix (ECM) interaction. Secreted protein, acidic and rich in cysteine (SPARC) is an ECM protein with many biological functions that is... more
Liver fibrosis is an active process that involves changes in cell-cell and cell-extracellular matrix (ECM) interaction. Secreted protein, acidic and rich in cysteine (SPARC) is an ECM protein with many biological functions that is overexpressed in cirrhotic livers and upregulated in activated hepatic stellate cells (aHSCs). We have recently shown that SPARC downregulation ameliorates liver fibrosis in vivo. To uncover the cellular mechanisms involved, we have specifically knocked down SPARC in two aHSC lines [the CFSC-2G (rat) and the LX-2 (human)] and in primary cultured rat aHSCs. Transient downregulation of SPARC in hepatic stellate cells (HSCs) did not affect their proliferation and had only minor effects on apoptosis. However, SPARC knockdown increased HSC adhesion to fibronectin and significantly decreased their migration toward PDFG-BB and TGF-β(1). Interestingly, TGF-β(1) secretion by HSCs was reduced following SPARC small interfering RNA (siRNA) treatment, and preincubation with TGF-β(1) restored the migratory capacity of SPARC siRNA-treated cells through mechanisms partially independent from TGF-β(1)-mediated induction of SPARC expression; thus SPARC knockdown seems to exert its effects on HSCs partially through modulation of TGF-β(1) expression levels. Importantly, collagen-I mRNA expression was reduced in SPARC siRNA-transfected HSCs. Consistent with previous results, SPARC knockdown in aHSCs was associated with altered F-actin expression patterns and deregulation of key ECM and cell adhesion molecules, i.e., downregulation of N-cadherin and upregulation of E-cadherin. Our data together suggest that the upregulation of SPARC previously reported for aHSCs partially mediates profibrogenic activities of TGF-β(1) and PDGF-BB and identify SPARC as a potential therapeutic target for liver fibrosis.