Behavior of CMPCs in unidirectional constrained and stress-free 3D hydrogels

Cardiomyocyte progenitor cells (CMPCs) are a candidate cell source for cardiac regenerative therapy. However, like other stem cells, after transplantation in the heart, cell retention and differentiation capacity of the CMPCs are low. Combining cells with biomaterials might overcome this problem. By serving as a (temporal) environment, the biomaterial can retain the cells and provide signals that enhance survival, proliferation and differentiation of the cells. To gain more insight into the effect that the encapsulation of CMPCs in a biomaterial has on their behavior, we cultured CMPCs in unidirectional constrained and stress-free collagen/Matrigel hydrogels. CMPCs cultured in 3D hydrogels stay viable and keep their cardiomyogenic profile independent of the application of strain. Moreover, the increased expression of Nkx2.5, myocardin and cTnT in 3D hydrogels compared to 2D cultures, suggests enhanced cardiomyogenic differentiation capacity of cells in 3D. Furthermore, increased expression of collagen I, collagen III, elastin and fibronectin and of the matrix remodeling enzymes MMP-1, MMP-2, MMP-9, and TIMP-1 and TIMP-2 in the 3D hydrogels is indicative of an enhanced matrix remodeling capacity of CMPCs in a 3D environment, independent of the application of strain. Interestingly, the additional application of static strain to the 3D hydrogels, as imposed by hydrogel constrainment, stabilized CMPC viability and proliferation, resulted in enhanced cardiac marker protein expression and appeared crucial for cellular organization and morphology. More specifically, CMPCs cultured in 3D collagen/Matrigel constrained hydrogels became readily mechanosensitive, had a rod-shaped morphology, and responded to the applied strain by orienting in the direction of the constraint. Overall, our data demonstrate the applicability of CMPCs in a 3D environment since encapsulation of CMPCs may stabilize survival and proliferation, can enhance the differentiation and remodeling capacity of the cells, and could induce cellular re-organization, which all may contribute to an improved efficiency of cardiac stem cell therapy.     

Human Olfactory Mucosa Stem Cells Delivery Using a Collagen Hydrogel: As a Potential Candidate for Bone Tissue Engineering

For bone tissue engineering, stem cell-based therapy has become a promising option. Recently, cell transplantation supported by polymeric carriers has been increasingly evaluated. Herein, we encapsulated human olfactory ectomesenchymal stem cells (OE-MSC) in the collagen hydrogel system, and their osteogenic potential was assessed in vitro and in vivo conditions. Collagen type I was composed of four different concentrations of (4 mg/mL, 5 mg/mL, 6 mg/mL, 7 mg/mL). SDS-Page, FTIR, rheologic test, resazurin assay, live/dead assay, and SEM were used to characterize collagen hydrogels. OE-MSCs encapsulated in the optimum concentration of collagen hydrogel and transplanted in rat calvarial defects. The tissue samples were harvested after 4- and 8-weeks post-transplantation and assessed by optical imaging, micro CT, and H&E staining methods. The highest porosity and biocompatibility were confirmed in all scaffolds. The collagen hydrogel with 7 mg/mL concentration was presented as optimal mechanical properties close to the naïve bone. Furthermore, the same concentration illustrated high osteogenic differentiation confirmed by real-time PCR and alizarin red S methods. Bone healing has significantly occurred in defects treated with OE-MSCs encapsulated hydrogels in vivo. As a result, OE-MSCs with suitable carriers could be used as an appropriate cell source to address clinical bone complications.     

Correlations on the Structure and Properties of Collagen Hydrogels Produced by E-Beam Crosslinking

In this study, a collagen hydrogel using collagen exclusively produced in Romania, was obtained by electron beam (e-beam) crosslinking. The purpose of our study is to obtain new experimental data on the crosslinking of collagen and to predict as faithfully as possible, its behavior at high irradiation doses and energies. To pursue this, the correlations between macromolecular structure and properties of collagen hydrogels were determined by rheological analysis, Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Differential Scanning Calorimetry (DSC), respectively. The gel fraction, swelling degree, and network parameters of the collagen hydrogels were also investigated at different irradiation doses. Through experimental exploration, we concluded that irradiation with e-beam up to 25 kGy induces crosslinking processes in collagen structure without producing advanced degradation processes. E-beam technology is a great method to develop new materials for medical applications without adding other chemical reagents harmful to human health. The future aim is to develop new wound dressings for rapid healing based on collagen, through irradiation technologies.     

Recent Advancements in 3D Printing of Polysaccharide Hydrogels in Cartilage Tissue Engineering

The application of hydrogels coupled with 3-dimensional (3D) printing technologies represents a modern concept in scaffold development in cartilage tissue engineering (CTE). Hydrogels based on natural biomaterials are extensively used for this purpose. This is mainly due to their excellent biocompatibility, inherent bioactivity, and special microstructure that supports tissue regeneration. The use of natural biomaterials, especially polysaccharides and proteins, represents an attractive strategy towards scaffold formation as they mimic the structure of extracellular matrix (ECM) and guide cell growth, proliferation, and phenotype preservation. Polysaccharide-based hydrogels, such as alginate, agarose, chitosan, cellulose, hyaluronan, and dextran, are distinctive scaffold materials with advantageous properties, low cytotoxicity, and tunable functionality. These superior properties can be further complemented with various proteins (e.g., collagen, gelatin, fibroin), forming novel base formulations termed “proteo-saccharides” to improve the scaffold’s physiological signaling and mechanical strength. This review highlights the significance of 3D bioprinted scaffolds of natural-based hydrogels used in CTE. Further, the printability and bioink formation of the proteo-saccharides-based hydrogels have also been discussed, including the possible clinical translation of such materials.     

Hybrid Gel Composed of Native Heart Matrix and Collagen Induces Cardiac Differentiation of Human Embryonic Stem Cells without Supplemental Growth Factors

Our goal was to assess the ability of native heart extracellular matrix (ECM) to direct cardiac differentiation of human embryonic stem cells (hESCs) in vitro. In order to probe the effects of cardiac matrix on hESC differentiation, a series of hydrogels was prepared from decellularized ECM from porcine hearts by mixing ECM and collagen type I at varying ratios. Maturation of cardiac function in embryoid bodies formed from hESCs was documented in terms of spontaneous contractile behavior and the mRNA and protein expression of cardiac markers. Hydrogel with high ECM content (75% ECM, 25% collagen, no supplemental soluble factors) increased the fraction of cells expressing cardiac marker troponin T, when compared with either hydrogel with low ECM content (25% ECM, 75% collagen, no supplemental soluble factors) or collagen hydrogel (100% collagen, with supplemental soluble factors). Furthermore, cardiac maturation was promoted in high-ECM content hydrogels, as evidenced by the striation patterns of cardiac troponin I and by upregulation of Cx43 gene. Consistently, high-ECM content hydrogels improved the contractile function of cardiac cells, as evidenced by increased numbers of contracting cells and increased contraction amplitudes. The ability of native ECM hydrogel to induce cardiac differentiation of hESCs without the addition of soluble factors makes it an attractive biomaterial system for basic studies of cardiac development and potentially for the delivery of therapeutic cells into the heart.     

Synthetic matrix metalloproteinase-sensitive hydrogels for the conduction of tissue regeneration: engineering cell-invasion characteristics

Synthetic hydrogels have been molecularly engineered to mimic the invasive characteristics of native provisional extracellular matrices: a combination of integrin-binding sites and substrates for matrix metalloproteinases (MMP) was required to render the networks degradable and invasive by cells via cell-secreted MMPs. Degradation of gels was engineered starting from a characterization of the degradation kinetics (k(cat) and K(m)) of synthetic MMP substrates in the soluble form and after crosslinking into a 3D hydrogel network. Primary human fibroblasts were demonstrated to proteolytically invade these networks, a process that depended on MMP substrate activity, adhesion ligand concentration, and network crosslinking density. Gels used to deliver recombinant human bone morphogenetic protein-2 to the site of critical defects in rat cranium were completely infiltrated by cells and remodeled into bony tissue within 4 wk at a dose of 5 microg per defect. Bone regeneration was also shown to depend on the proteolytic sensitivity of the matrices. These hydrogels may be useful in tissue engineering and cell biology as alternatives for naturally occurring extracellular matrix-derived materials such as fibrin or collagen.     

Differential response to growth factor by rat mammary epithelium plated on different collagen substrata in serum-free medium.

Primary cultures of rat mammary epithelial cells proliferate and synthesize basement membrane collagen (type IV collagen) in a serum-free medium supplemented with epidermal growth factor (EGF), hydrocortisone or dexamethasone, insulin, transferrin, and Pedersen fetuin. The growth response of the cells to EGF and glucocorticoids but not to insulin or transferrin varies depending on the substratum on which the cells are plated. Cell growth is 4 times more sensitive to omission of EGF or glucocorticoid on type I collagen or plastic substratum than on type IV collagen substratum. The mechanism by which these two growth factors differentially affect cell growth appears to be linked to an increase in type IV collagen synthesis and a stabilization of secreted type IV collagen in the extracellular matrix. Glucocorticoids suppress the elaboration of type IV collagenolytic activity by the cells whereas EGF stimulates amino acid incorporation into type IV collagen. The results suggest that EGF and glucocorticoids affect mammary epithelial cell growth by facilitating the accumulation of the appropriate cell substratum.     

Collagen/Chitosan Gels Cross-Linked with Genipin for Wound Healing in Mice with Induced Diabetes

Diabetes mellitus continues to be one of the most common diseases often associated with diabetic ulcers. Chitosan is an attractive biopolymer for wound healing due to its biodegradability, biocompatibility, mucoadhesiveness, low toxicity, and hemostatic effect. A panel of hydrogels based on chitosan, collagen, and silver nanoparticels were produced to treat diabetic wounds. The antibacterial activity, cytotoxicity, swelling, rheological properties, and longitudinal sections of hydrogels were studied. The ability of the gels for wound healing was studied in CD1 mice with alloxan-induced diabetes. Application of the gels resulted in an increase in VEGF, TGF-b1, IL-1b, and TIMP1 gene expression and earlier wound closure in a comparison with control untreated wounds. All gels increased collagen deposition, hair follicle repair, and sebaceous glands formation. The results of these tests show that the obtained hydrogels have good mechanical properties and biological activity and have potential applications in the field of wound healing. However, clinical studies are required to compare the efficacy of the gels as animal models do not reproduce full diabetes pathology.     

Effect of gamma-interferon on collagen synthesis by normal and fibrotic human lung fibroblasts.

Increased lung collagen and increased collagen synthesis by lung fibroblasts is well recognized in pulmonary fibrosis. gamma-Interferon has been shown to inhibit collagen synthesis by fibroblasts. To understand its effect on lung fibroblasts we compared how this lymphokine affects the growth and collagen synthesis of normal and fibrotic human lung fibroblasts. The results showed that gamma-IFN inhibited DNA synthesis in all fibroblast strains examined. Both collagen production and type 1 mRNA levels were reduced in three normal and two fibrotic cell strains exposed to gamma-IFN, while they were not affected in one strain from fibrotic lung. Even though an occasional cell was unaffected by the gamma-IFN, collagen mRNA level was reduced in most cells and it remained reduced for 48 h after removing the gamma-IFN. These results show that gamma-IFN inhibits the growth of fibroblast cultures derived from normal and fibrotic human lungs and suppresses collagen synthesis in most of these cells.     

Transforming growth factor beta 1 selectively augments collagen synthesis by human intestinal smooth muscle cells

Intestinal smooth muscle cells play a major role in the stricture formation that complicates chronic intestinal inflammation, by proliferating and producing collagen. Transforming growth factor beta 1 has been identified as an important inflammatory mediator in the fibrotic response of human tissue to inflammation. To determine whether this mediator might be involved in intestinal fibrosis, the effect of transforming growth factor beta 1 on collagen production and proliferation by human intestinal smooth muscle cells was studied in vitro. Cells in the second passage were grown to subconfluence in medium containing 10% Nu-Serum (Collaborative Research Inc., Bedford, MA), after which the concentration of Nu-Serum was decreased. Forty-eight hours later, transforming growth factor beta 1 was added to the culture medium to achieve concentrations of 1-500 pmol/L. After 24 hours exposure to the transforming growth factor beta 1, cellular collagen synthesis was determined by the uptake of [3H]proline into collagenase-sensitive protein. Transforming growth factor beta 1 caused a 100% increase in collagen production and a 40% increase in noncollagen protein production per cell, reflecting an increase in relative collagen synthesis of 58%. This effect was maximal at a concentration of 10 pmol/L. Epidermal growth factor, by comparison, had no significant effect on relative collagen synthesis. Transforming growth factor beta 1 caused a significant increase in the uptake of methylaminoisobutyric acid, a nonmetabolized amino acid analog, into the cells at 10 pmol/L. However, this effect was small (20% increase) compared with the effect on the uptake of proline into collagen (100% increase) at this concentration. When cell proliferation was examined by the uptake of [3H]thymidine, transforming growth factor beta 1 had no effect, whereas epidermal growth factor (1000 pmol/L) caused a 94% increase. Transforming growth factor beta 1 selectively augments collagen production by human intestinal smooth muscle cells in vitro. This effect is potent and is not related to effects on either cell proliferation or amino acid uptake. These data suggest that transforming growth factor beta 1 has an important role as an inflammatory mediator in the pathogenesis of intestinal fibrosis.     

Distribution of extracellular matrix proteins in pancreatic ductal adenocarcinoma and its influence on tumor cell proliferation in vitro

Affinity-purified antibodies to major components of the extracellular matrix (fibronectin and collagen type I) and basal lamina (laminin) were used in indirect immunofluorescence studies on frozen sections of 12 pancreatic ductal adenocarcinoma of the human and on sections of normal and inflamed pancreatic tissue of the same patients. Laminin-specific immunoreactivity was distributed in close correlation to the grade of differentiation of the tumor tissue. Intact basement membranes, also with some structural irregularities were found only in the highest grade of differentiation where tumor cells grew as tubular structures. With progressive dedifferentiation basal laminae were either absent or the laminin-positive material was focally distributed without spatial association with tumor cells. In all cases of pancreatic tumors a remarkable increase in interstitial connective tissue was observed, as demonstrated by antibodies specific for human collagen type I and for human serum fibronectin. Tumor extracts contained high amounts of collagen type I and V but no significant amount of collagen type III as visualized by analytical SDS gel electrophoresis. A similar distribution of collagen types was observed in lymph node and liver metastases, and in tumors xenografted into nude mice. Since previously a close correlation between grading and growth kinetics of primary tumors had been observed, in vitro experiments were performed analyzing the effect of purified extracellular matrix proteins on tumor cell proliferation. In vitro cultivation of two established cell lines of pancreatic carcinoma on collagen type I or on laminin resulted in an arrest of proliferation on laminin substrates, while normal proliferation comparable to growth on regular culture dishes was found using collagen type I and fibronectin as substrates. Fine structural studies demonstrated a higher degree of cell differentiation in the presence of laminin, as compared to collagen type I or fibronectin.     

Applications of Hydrogel with Special Physical Properties in Bone and Cartilage Regeneration

Hydrogel is a polymer matrix containing a large amount of water. It is similar to extracellular matrix components. It comes into contact with blood, body fluids, and human tissues without affecting the metabolism of organisms. It can be applied to bone and cartilage tissues. This article introduces the high-strength polymer hydrogel and its modification methods to adapt to the field of bone and cartilage tissue engineering. From the perspective of the mechanical properties of hydrogels, the mechanical strength of hydrogels has experienced from the weak-strength traditional hydrogels to the high-strength hydrogels, then the injectable hydrogels were invented and realized the purpose of good fluidity before the use of hydrogels and high strength in the later period. In addition, specific methods to give special physical properties to the hydrogel used in the field of bone and cartilage tissue engineering will also be discussed, such as 3D printing, integrated repair of bone and cartilage tissue, bone vascularization, and osteogenesis hydrogels that regulate cell growth, antibacterial properties, and repeatable viscosity in humid environments. Finally, we explain the main reasons and contradictions in current applications, look forward to the research prospects in the field of bone and cartilage tissue engineering, and emphasize the importance of conducting research in this field to promote medical progress.     

A Direct Electric Field-Aided Biomimetic Mineralization System for Inducing the Remineralization of Dentin Collagen Matrix

This in vitro study aimed to accelerate the remineralization of a completely demineralized dentine collagen block in order to regenerate the dentinal microstructure of calcified collagen fibrils by a novel electric field-aided biomimetic mineralization system in the absence of non-collagenous proteins. Completely demineralized human dentine slices were prepared using ethylene diamine tetraacetic acid (EDTA) and treated with guanidine hydrochloride to extract the bound non-collagenous proteins. The completely demineralized dentine collagen blocks were then remineralized in a calcium chloride agarose hydrogel and a sodium hydrogen phosphate and fluoride agarose hydrogel. This process was accelerated by subjecting the hydrogels to electrophoresis at 20 mA for 4 and 12 h. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM) were used to evaluate the resultant calcification of the dentin collagen matrix. SEM indicated that mineral particles were precipitated on the intertubular dentin collagen matrix; these densely packed crystals mimicked the structure of the original mineralized dentin. However, the dentinal tubules were not occluded by the mineral crystals. XRD and EDX both confirmed that the deposited crystals were fluorinated hydroxyapatite. TEM revealed the existence of intrafibrillar and interfibrillar mineralization of the collagen fibrils. A novel electric field-aided biomimetic mineralization system was successfully developed to remineralize a completely demineralized dentine collagen matrix in the absence of non-collagenous proteins. This study developed an accelerated biomimetic mineralization system which can be a potential protocol for the biomineralization of dentinal defects.     

Selective inhibition of type I collagen synthesis in osteoblastic cells by epidermal growth factor

We have investigated the effect of epidermal growth factor (EGF) on collagen metabolism in clonal MC3T3-E1 cells, an osteoblastic cell line derived from newborn mouse calvaria. EGF significantly increased DNA synthesis, but decreased collagen production. We analyzed the amount of total collagen synthesis and degradation products of collagen together with the level of the enzyme responsible for extracellular collagen degradation, to investigate whether the decreased collagen production was due to a decrease in total collagen synthesis or to an increase in collagen degradation. Total collagen synthesis, determined by total hydroxyproline synthesized, was significantly decreased in cells cultured in medium containing EGF, but the amount of collagen degradation products and the level of animal collagenase activity were not increased. Analysis of the collagen type produced by the cells in the absence of EGF showed that 95% of the collagen recovered was type I and 3% was type III. The decreased level of collagen accumulated by cells cultured in the presence of EGF was explained only by the decreased rate of type I collagen synthesis. These results indicate that EGF selectively inhibits type I collagen synthesis in the clonal osteoblastic cell line, MC3T3-E1.     

Growth factor-induced angiogenesis in vivo requires specific cleavage of fibrillar type I collagen

The contribution of specific type I collagen remodeling in angiogenesis was studied in vivo using a quantitative chick embryo assay that measures new blood vessel growth into well-defined fibrillar collagen implants. In response to a combination of basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF), a strong angiogenic response was observed, coincident with invasion into the collagen implants of activated fibroblasts, monocytes, heterophils, and endothelial cells. The angiogenic effect was highly dependent on matrix metalloproteinase (MMP) activity, because new vessel growth was inhibited by both a synthetic MMP inhibitor, BB3103, and a natural MMP inhibitor, TIMP-1. Multiple MMPs were detected in the angiogenic tissue including MMP-2, MMP-13, MMP-16, and a recently cloned MMP-9-like gelatinase. Using this assay system, wild-type collagen was compared to a unique collagenase-resistant collagen (r/r), with regard to the ability of the respective collagen implants to support cell invasion and angiogenesis. It was found that collagenase-resistant collagen constitutes a defective substratum for angiogenesis. In implants made with r/r collagen there was a substantial reduction in the number of endothelial cells and newly formed vessels. The presence of the r/r collagen, however, did not reduce the entry into the implants of other cell types, that is, activated fibroblasts and leukocytes. These results indicate that fibrillar collagen cleavage at collagenase-specific sites is a rate-limiting event in growth factor-stimulated angiogenesis in vivo.     

Proliferation of mouse uterine epithelial cells in vitro

Although estrogens can stimulate the growth of uterine epithelial cells in vivo, there is no clear effect of estrogens on the in vitro growth of epithelial cells from reproductive tract tissues; thus, we have established a defined culture system for mouse uterine epithelial cells. Pieces of uteri from immature CD-1 mice (21-23 days of age) were treated with trypsin, and the epithelial fragments were separated, enriched by Percoll gradient centrifugation, and seeded on collagen gels prepared from rat tail tendon. Initially, the cells were cultured in a 1:1 mixture of Ham's F-12 and Dulbecco's Modified Eagle's Medium supplemented with epidermal growth factor (EGF; 10 ng/ml), insulin (10 micrograms/ml), transferrin (10 micrograms/ml), hydrocortisone (0.1 micrograms/ml), and vitamin A (10 ng/ml). The cells formed a monolayer on the collagen gel within 1-2 days, but with time, cells began to detach from the gel. Further studies revealed that the attachment and growth of these cells on collagen were markedly influenced by the calcium concentration. It was found that lowering the calcium concentration from 1.05 to 0.05-0.1 mM dramatically suppressed cell detachment; the number of cells doubled after 7 days of culture. Proliferation of uterine epithelial cells was enhanced by EGF, but not by fibroblast growth factor, platelet-derived growth factor, nerve growth factor, multiplication-stimulating activity, or somatomedin-C. The uterine epithelial cells exhibited a single class of high affinity binding sites for [125I]iodo-EGF (Kd, approximately 1.8 nM), with approximately 5 X 10(4) receptors/cell; binding was inhibited by EGF but not by the other polypeptides. This cell culture system will aid in our investigations on hormonal effects on the growth and differentiation of estrogen target cells.     

Connective tissue growth factor hammerhead ribozyme attenuates human hepatic stellate cell function

AIM: To determine the effect of hammerhead ribozyme targeting connective tissue growth factor (CCN2) on human hepatic stellate cell (HSC) function. METHODS: CCN2 hammerhead ribozyme cDNA plus two self-cleaving sequences were inserted into pTriEx2 to produce pTriCCN2-Rz. Each vector was individually transfected into cultured LX-2 human HSCs, which were then stimulated by addition of transforming growth factor (TGF)-b1 to the culture medium. Semiquantitative RT-PCR was used to determine mRNA levels for CCN2 or collagen Ⅰ, while protein levels of each molecule in cell lysates and conditioned medium were measured by ELISA. Cell-cycle progression of the transfected cells was assessed by flow cytometry. RESULTS: In pTriEx2-transfected LX-2 cells, TGF-β1 treatment caused an increase in the mRNA level for CCN2 or collagen Ⅰ, and an increase in produced and secreted CCN2 or extracellular collagen Ⅰ protein levels. pTriCCN2-Rz-transfected LX-2 cells showed decreased basal CCN2 or collagen mRNA levels, as well as produced and secreted CCN2 or collagen Ⅰ protein. Furthermore, the TGF-b1-induced increase in mRNA or protein for CCN2 or collagen Ⅰ was inhibited partially in pTriCCN2-Rz-transfected LX-2 cells. Inhibition of CCN2 using hammerhead ribozyme cDNA resulted in fewer of the cells transitioning into S phase. CONCLUSION: Endogenous CCN2 is a mediator of basal or TGF-b1-induced collagen Ⅰ production in human HSCs and regulates entry of the cells into Sphase.     

Connective tissue growth factor hammerhead ribozyme attenuates human hepatic stellate cell function

AIM： To determine the effect of hammerhead ribozyme targeting connective tissue growth factor （CCN2） on human hepatic stellate cell （HSC） function.
METHODS： CCN2 hammerhead ribozyme cDNA plus two self-cleaving sequences were inserted into pTriEx2 to produce pTriCCN2-Rz. Each vector was individually transfected into cultured LX-2 human HSCs, which were then stimulated by addition of transforming growth factor （TGF）-β1 to the culture medium. Semiquantitative RT-PCR was used to determine mRNA levels for CCN2 or collagen I, while protein levels of each molecule in cell /ysates and conditioned medium were measured by ELISA. Cell-cycle progression of the transfected cells was assessed by flow cytometry.
RESULTS： In pTriEx2-transfected LX-2 cells, TGF-β1 treatment caused an increase in the mRNA level for CCN2 or collagen I, and an increase in produced and secreted CCN2 or extracellular collagen I protein levels, pTriCCN2-Rz-transfected LX-2 cells showed decreased basal CCN2 or collagen mRNA levels, as well as produced and secreted CCN2 or collagen I protein. Furthermore, the TGF-β1-induced increase in mRNA or protein for CCN2 or collagen I was inhibited partially in pTriCCN2-Rz-transfected LX-2 cells. Inhibition of CCN2 using hammerhead ribozyme cDNA resulted in fewer of the cells transitioning into S phase.
CONCLUSION： Endogenous CCN2 is a mediator of basal or TGF-β1-induced collagen I production in human HSCs and regulates entry of the cells into S phase.