Intractable itch relieved by 4-phenylbutyrate therapy in patients with progressive familial intrahepatic cholestasis type 1

Background

Progressive familial intrahepatic cholestasis type 1 (PFIC1), an inherited liver disease caused by mutations in ATP8B1, progresses to severe cholestasis with a sustained intractable itch. Currently, no effective therapy has been established for PFIC1. Decreased function of the bile salt export pump (BSEP) in hepatocytes is suggested to be responsible for the severe cholestasis observed in PFIC1. We found a previously unidentified pharmacological effect of 4-phenylbutyrate (4PB) that increases the expression and function of BSEP. Here, we tested 4PB therapy in three patients with PFIC1.

Methods

The therapeutic potency of 4PB in these patients was tested by oral administration of this drug with gradually increasing dosage (200, 350, and 500 mg/kg/day) for 6 months. Biochemical, histological, and clinical data were collected.

Results

4PB therapy had no beneficial effect on the patients’ liver functions, as assessed by biochemical and histological analyses, despite an increase in hepatic BSEP expression. However, therapy with 4PB at a dosage of 350 or 500 mg/kg/day significantly relieved the intractable itch. Serum levels of potential pruritogens in cholestasis were much higher than the reference ranges during the 4PB therapy.

Conclusions

4PB therapy may be a new medication for patients with intractable cholestatic pruritus and may improve quality of life for patients and their families.

Gene expression signature for biliary atresia and a role for interleukin-8 in pathogenesis of experimental disease

Biliary atresia (BA) is a progressive fibroinflammatory obstruction of extrahepatic bile ducts that presents as neonatal cholestasis. Due to the overlap in clinical, biochemical, and histological features with other causes of cholestasis, the diagnosis requires an intraoperative cholangiogram. Thus, we determined whether diseased livers express a gene expression signature unique to BA. Applying stringent statistical analysis to a genome-wide liver expression platform of 64 infants with BA at the time of diagnosis, 14 age-appropriate subjects with intrahepatic cholestasis as diseased controls and seven normal controls, we identified 15 genes uniquely expressed in BA with an accuracy of 92.3%. Among these genes, IL8 and LAMC2 were sufficient to classify subjects with BA distinctly from diseased controls with an area under the curve of 0.934 (95% confidence interval [CI]: 0.84-1.03), sensitivity of 96.9%, and specificity of 85.7% using their combined first principal component. Direct measurement of interleukin (IL)8 protein in the serum, however, was not different between the two groups. To investigate whether the liver-restricted increase in IL8 was relevant to disease pathogenesis, we inactivated the signaling of IL8 homologs by genetic targeting of the Cxcr2 receptor in a murine model of experimental BA. Disruption of Cxcr2 shortened the duration of cholestasis, decreased the incidence of bile duct obstruction, and improved survival above wild-type neonatal mice.

CONCLUSION

The hepatic expression of IL8 and LAMC2 has high sensitivity for BA at diagnosis and may serve as a biomarker of disease, with an important role for the IL8 signaling in experimental BA.

Biliary repair and carcinogenesis are mediated by IL-33-dependent cholangiocyte proliferation

Injury to the biliary epithelium triggers inflammation and fibrosis, which can result in severe liver diseases and may progress to malignancy. Development of a type 1 immune response has been linked to biliary injury pathogenesis; however, a subset of patients with biliary atresia, the most common childhood cholangiopathy, exhibit increased levels of Th2-promoting cytokines. The relationship among different inflammatory drivers, epithelial repair, and carcinogenesis remains unclear. Here, we determined that the Th2-activating cytokine IL-33 is elevated in biliary atresia patient serum and in the livers and bile ducts of mice with experimental biliary atresia. Administration of IL-33 to WT mice markedly increased cholangiocyte proliferation and promoted sustained cell growth, resulting in dramatic and rapid enlargement of extrahepatic bile ducts. The IL-33-dependent proliferative response was mediated by an increase in the number of type 2 innate lymphoid cells (ILC2s), which released high levels of IL-13 that in turn promoted cholangiocyte hyperplasia. Induction of the IL-33/ILC2/IL-13 circuit in a murine biliary injury model promoted epithelial repair; however, induction of this circuit in mice with constitutive activation of AKT and YAP in bile ducts induced cholangiocarcinoma with liver metastases. These findings reveal that IL-33 mediates epithelial proliferation and suggest that activation of IL-33/ILC2/IL-13 may improve biliary repair and disruption of the circuit may block progression of carcinogenesis.

Integrative genomics identifies candidate microRNAs for pathogenesis of experimental biliary atresia

Background

Biliary atresia is a fibroinflammatory obstruction of extrahepatic bile duct that leads to end-stage liver disease in children. Despite advances in understanding the pathogenesis of biliary atresia, very little is known about the role of microRNAs (miRNAs) in onset and progression of the disease. In this study, we aimed to investigate the entire biliary transcriptome to identify miRNAs with potential role in the pathogenesis of bile duct obstruction.

Results

By profiling the expression levels of miRNA in extrahepatic bile ducts and gallbladder (EHBDs) from a murine model of biliary atresia, we identified 14 miRNAs whose expression was suppressed at the times of duct obstruction and atresia (≥2 fold suppression, P < 0.05, FDR 5%). Next, we obtained 2,216 putative target genes of the 14 miRNAs using in silico target prediction algorithms. By integrating this result with a genome-wide gene expression analysis of the same tissue (≥2 fold increase, P < 0.05, FDR 5%), we identified 26 potential target genes with coordinate expression by the 14 miRNAs. Functional analysis of these target genes revealed a significant relevance of miR-30b/c, -133a/b, -195, -200a, -320 and −365 based on increases in expression of at least 3 target genes in the same tissue and 1^st-to-3^rd tier links with genes and gene-groups regulating organogenesis and immune response. These miRNAs showed higher expression in EHBDs above livers, a unique expression in cholangiocytes and the subepithelial compartment, and were downregulated in a cholangiocyte cell line after RRV infection.

Conclusions

Integrative genomics reveals functional relevance of miR-30b/c, -133a/b, -195, -200a, -320 and −365. The coordinate expression of miRNAs and target genes in a temporal-spatial fashion suggests a regulatory role of these miRNAs in pathogenesis of experimental biliary atresia.

Replication of a GWAS signal in a Caucasian population implicates ADD3 in susceptibility to biliary atresia

In the United States, biliary atresia (BA) is the most frequent indication for liver transplantation in pediatric patients. BA is a complex disease, with suspected environmental and genetic risk factors. A genome-wide association study in Chinese patients identified association to the 10q24.2 (hg18) genomic region. This signal was upstream of two genes, XPNPEP1 and ADD3, both expressed in intrahepatic bile ducts. We tested association to this region in 171 BA patients and 1,630 controls of European descent and found the strongest signal to be at rs7099604 (p = 2.5 × 10(-3)) in intron 1 of the ADD3 gene. Moreover, expression data suggest that ADD3, but not XPNPEP1, is differentially expressed in BA patients. The role of ADD3 in biliary development is unclear, but our findings suggest that this gene may be functionally relevant for the development of BA.

The effects of C-type natriuretic peptide on craniofacial skeletogenesis

C-type natriuretic peptide (CNP) is a potent stimulator of long bone and vertebral development via endochondral ossification. In the present study, we investigated the effects of CNP on craniofacial skeletogenesis, which consists of both endochondral and membranous ossification. Morphometric analyses of crania from CNP knockout and transgenic mice revealed that CNP stimulates longitudinal growth along the cranial length, but does not regulate cranial width. CNP markedly increased the length of spheno-occipital synchondrosis in fetal murine organ cultures, and the thickness of cultured murine chondrocytes from the spheno-occipital synchondrosis or nasal septum, resulting in the stimulation of longitudinal cranial growth. Mandibular growth includes endochondral and membranous ossification; although CNP stimulated endochondral bone growth of condylar cartilage in cultured fetal murine mandibles, differences in the lengths of the lower jaw between CNP knockout or transgenic mice and wild-type mice were smaller than those observed for the lengths of the upper jaw. These results indicate that CNP primarily stimulates endochondral ossification in the craniofacial region and is crucial for midfacial skeletogenesis.

Phenotypes of CCAAT/enhancer-binding protein beta deficiency: hyperdontia and elongated coronoid process

OBJECTIVES

This investigation aimed to conduct a case-control study of mandibular morphology and dental anomalies to propose a relationship between mandibular/dental phenotypes and deficiency of CCAAT/enhancer-binding protein beta (CEBPB).

MATERIALS AND METHODS

Skulls of CEBPB(-/-), CEBPB(+/-) and CEBPB(+/+) mice were inspected with micro-computed tomography. Mandibular morphology was assessed with a method of Euclidean distance matrix analysis.

RESULTS

Elongation of the coronoid process was identified in CEBPB(+/-) (P ≤ 0.046) and CEBPB(-/-) 12-month-olds (P ≤ 0.028) but not in 14-day-olds (P ≥ 0.217) and 0-day-olds (P ≥ 0.189) of either genotype. Formation of supernumerary teeth in CEBPB(-/-) adult mice was demonstrated (χ(2) = 6.00, df = 1, P = 0.014).

CONCLUSIONS

CEBPB deficiency was related to elongation of the coronoid process and formation of supernumerary teeth. The mandibular and dental phenotypes of CEBPB deficiency were unseen by the 14th day after birth. Future investigations into the influence of CEBPB on mandibular and dental development are needed.

Th2 signals induce epithelial injury in mice and are compatible with the biliary atresia phenotype

Biliary atresia (BA) is a destructive cholangiopathy of childhood in which Th1 immunity has been mechanistically linked to the bile duct inflammation and obstruction that culminate in liver injury. Based on reports of decreased Th1 cytokines in some patients and the development of BA in mice lacking CD4+ T cells, we hypothesized that Th1-independent mechanisms can also activate effector cells and induce BA. Here, we tested this hypothesis using Stat1-/- mice, which lack the ability to mount Th1 immune responses. Infection of Stat1-/- mice with rhesus rotavirus type A (RRV) on postnatal day 1 induced a prominent Th2 response, duct epithelial injury and obstruction within 7 days, and atresia shortly thereafter. A high degree of phosphorylation of the Th2 transcription factor Stat6 was observed; however, concurrent inactivation of Stat1 and Stat6 in mice did not prevent BA after RRV infection. In contrast, depletion of macrophages or combined loss of Il13 and Stat1 reduced tissue infiltration by lymphocytes and myeloid cells, maintained epithelial integrity, and prevented duct obstruction. In concordance with our mouse model, humans at the time of BA diagnosis exhibited differential hepatic expression of Th2 genes and serum Th2 cytokines. These findings demonstrate compatibility between Th2 commitment and the pathogenesis of BA, and suggest that patient subgrouping in future clinical trials should account for differences in Th2 status.

Biliary atresia: will blocking inflammation tame the disease?

Biliary atresia is the most common cholangiopathy of childhood. With complete obstruction of segments or the entire length of extrahepatic bile ducts, the timely pursuit of hepatoportoenterostomy is the best strategy to restore bile drainage. However, even with prompt surgical intervention, ongoing injury of intrahepatic bile ducts and progressive cholangiopathy lead to end-stage cirrhosis. The pace of disease progression is not uniform; it may relate to clinical forms of disease and/or staging of liver pathology at diagnosis. Although the etiology of disease is not yet defined, several biological processes have been linked to pathogenic mechanisms of bile duct injury. Among them, there is increasing evidence that the immune system targets the duct epithelium and disrupts bile flow. We discuss how careful clinical phenotyping, staging of disease, and basic mechanistic research are providing insights into clinical trial designs and directions for development of new therapies to block progression of disease.

Major role of apolipoprotein B in cycloheximide-induced acute hepatic steatosis in mice

AIM

  Hepatic steatosis accompanied by impaired protein synthesis is often observed in hepatic dysfunction. To assess whether protein synthesis inhibition directly induces hepatic steatosis, we investigated the molecular mechanisms of cycloheximide (CHX)-induced fatty liver mice.

METHODS

  C57/BL6CR mice were i.p. administrated CHX (20 mg/kg) three times every 4 h to induce hepatic steatosis. Hepatic lipid secretion, fatty acid oxidation, hepatic lipogenesis and hepatic lipid uptake were evaluated.

RESULTS

  Twenty-four hours after the first CHX injection, hepatic lipid levels increased in CHX-treated mice to 1.8-fold of that in controls but returned to normal within 48 h. The hepatic triglyceride (TG) secretion rate decreased significantly to 22% of controls, and the apolipoprotein B (apoB) protein level, but not microsomal TG transfer protein, decreased in CHX-treated mice. The apob gene expression was not significantly different between controls and CHX-treated mice. On the other hand, plasma free fatty acid and lipogenic protein levels did not increase and plasma β-hydroxybutyrate level remained stable, suggesting that the coordinated balance between fatty acid oxidation, hepatic lipid uptake and lipogenesis was not disrupted in this model. Cellular lipid accumulation and decreased cellular and secreted apoB were also observed in CHX-treated HepG2 cells. Knockdown of apoB in HepG2 cells also resulted in the cellular TG accumulation.

CONCLUSION

  We demonstrated that decreased hepatic lipid secretion due to acute apoB reduction is involved in the pathogenesis of CHX-induced liver steatosis.

Clinical phenotype and endocrinological investigations in a patient with a mutation in the MCT8 thyroid hormone transporter

Thyroid hormones are known to be essential for growth, development, and metabolism. Recently, the monocarboxylate transporter 8 (MCT8) was identified as a thyroid hormone transporter, and MCT8 mutations have been associated with Allan-Herndon-Dudley syndrome, an X linked condition characterized by severe mental retardation, dysarthria, athetoid movements, muscle hypoplasia, and spastic paraplegia. Here we describe in detail the clinical and biochemical features and the response to thyroid hormone (L-thyroxine (LT4)) administration in a boy with an MCT8 mutation (c.1649delA) that truncates the protein in the twelfth transmembrane domain. It is of note that brain magnetic resonance imaging (MRI) revealed delayed myelination from infancy. Endocrine functions other than thyroid hormone regulation and metabolism were intact, resulting in normal hypothalamic/pituitary function tests. While LT4 administration suppressed thyrotropin (TSH) secretion, no significant changes in thyroid hormone values or clinical symptoms were observed.

CONCLUSION

the characteristic thyroid hormone function tests and brain MRI findings may allow screening of high-risk populations for a better understanding of MCT8 pathophysiology.

Regeneration of articular cartilage defects in the temporomandibular joint of rabbits by fibroblast growth factor-2: a pilot study

The purpose of this study was to investigate the therapeutic usefulness of fibroblast growth factor-2 (FGF-2) in rabbit temporomandibular joints (TMJ) with osteoarthritis. A 10-mm(3) defect was bored in the surface of the mandibular condyle head. The animals were divided into four groups: two test groups in which the defect was filled with lyophilized collagen containing 0.1 or 1.0microg of FGF-2, and two control groups, in which the defects were filled with lyophilized collagen without FGF-2 or left empty. The defective sites were examined under a light microscope 3 weeks after surgery. Initiation of cartilage formation was observed in the defects filled with 0.1microg of FGF-2, but only a small amount of cartilage was found in the defects of the 1.0-mug FGF-2- treated group. In the control groups, soft-tissue repair only or no tissue repair was found. In vivo, a dose of 0.1microg of FGF-2 can stimulate articular cartilage restoration in defects of the TMJ in rabbits, although determining the effective concentration range of FGF-2 may be difficult. The present results suggest that an optimum concentration of FGF-2 could restore defects of TMJ articular cartilage clinically.

Wnt/Lrp/beta-catenin signaling suppresses adipogenesis by inhibiting mutual activation of PPARgamma and C/EBPalpha

Wnt/beta-catenin signaling has been implicated in repressing adipogenesis. Several lines of evidence show that the possible mechanism is blockade of PPARgamma induction. However, the precise mechanisms remain to be elucidated. In this study, we demonstrated that Wnt3a conditioned medium suppresses C/EBPbeta/delta-induced adipogenesis of 3T3-L1 cells by inhibiting PPARgamma induction. In addition, the mutual activation of PPARgamma and C/EBPalpha was also repressed in the presence of Wnt3a. To further investigate the role of the canonical Wnt pathway in adipogenesis, we used mouse embryonic fibroblasts (MEFs) isolated from Lrp6-deficient embryos. Contrary to wild-type MEFs, Lrp6-deficient MEFs showed spontaneous adipogenesis and escaped the suppressive effect of exogenous Wnt3a. These findings suggest a critical role of Wnt/Lrp6/beta-catenin signaling in adipogenesis and cell fate decision of mesenchymal stem cells.

Comparison of laser ray-tracing and skiascopic ocular wavefront-sensing devices

PURPOSE

To compare two wavefront-sensing devices based on different principles.

METHODS

Thirty-eight healthy eyes of 19 patients were measured five times in the reproducibility study. Twenty eyes of 10 patients were measured in the comparison study. The Tracey Visual Function Analyzer (VFA), based on the ray-tracing principle and the Nidek optical pathway difference (OPD)-Scan, based on the dynamic skiascopy principle were compared. Standard deviation (SD) of root mean square (RMS) errors was compared to verify the reproducibility. We evaluated RMS errors, Zernike terms and conventional refractive indexes (Sph, Cyl, Ax, and spherical equivalent).

RESULTS

In RMS errors reading, both devices showed similar ratios of SD to the mean measurement value (VFA: 57.5+/-11.7%, OPD-Scan: 53.9+/-10.9%). Comparison on the same eye showed that almost all terms were significantly greater using the VFA than using the OPD-Scan. However, certain high spatial frequency aberrations (tetrafoil, pentafoil, and hexafoil) were consistently measured near zero with the OPD-Scan.

CONCLUSION

Both devices showed similar level of reproducibility; however, there was considerable difference in the wavefront reading between machines when measuring the same eye. Differences in the number of sample points, centration, and measurement algorithms between the two instruments may explain our results.

Growth inhibition and apoptosis in liver myofibroblasts promoted by hepatocyte growth factor leads to resolution from liver cirrhosis

Liver cirrhosis is characterized by hepatic dysfunction with extensive accumulation of fibrous tissue in the liver. In response to chronic hepatic injury, hepatic portal myofibroblasts and activated hepatic stellate cells (HSCs) play a role in liver fibrosis. Although administration or gene expression of hepatocyte growth factor (HGF) leads to improvement in hepatic fibrosis/cirrhosis, the related mechanisms are not fully understood. We investigated mechanisms involved in resolution from liver cirrhosis by HGF, focusing on growth regulation and apoptosis in portal myofibroblasts. Cultured rat HSCs could not proliferate, were withdrawn after passage, and were replaced by proliferating portal myofibroblasts during the passages. In quiescent HSCs, c-Met receptor expression was undetected whereas c-Met receptor expression was detected in activated HSCs and liver myofibroblasts expressing alpha-smooth muscle actin (alpha-SMA), suggesting that activated HSCs and portal myofibroblasts are targets of HGF. For cultured rat portal myofibroblasts, HGF counteracted phosphorylation of extracellular signal-regulated kinase (Erk) 1/2 and mitogenic stimulus induced by platelet-derived growth factor, induced c-jun N-terminal kinase (JNK) 1 phosphorylation, and promoted apoptotic cell death. In the dimethylnitrosamine rat model of liver cirrhosis, administration of HGF suppressed proliferation while promoting apoptosis of alpha-SMA-positive cells in the liver, events that were associated with reduced hepatic expressions of alpha-SMA and histological resolution from liver cirrhosis. Growth inhibition and enhanced apoptosis in portal myofibroblasts by HGF are newly identified mechanisms aiding resolution from liver fibrosis/cirrhosis by HGF.

Tissue reaction at the implantation of recombinant human bone morphogenetic protein-2 into the skeletal muscle

Bone morphogenetic protein (BMP) is a unique cytokine that induces bony tissue in soft tissue. Tissue reactions at and around the implantation of recombinant human BMP-2 (rhBMP-2) into the soft tissue of rats and nonhuman primates were investigated. At the osteoinduced site of rats, massive trabeculae-lined osteoblasts and rich marrow were observed. At and around the nonosteoinduced sites of nonhuman primates, large clear nuclei were observed in reaction to rhBMP-2 implantation. The surrounding area was visually classified into zones 1, 2 and 3. Zone 3 was near the center of the implant. The area of nuclei, the major axis, the minor axis and the ratio of minor axis per major axis were image-analyzed in the histological views. In zones 1, 2 and 3, the nuclear areas were 18.0 (3.1) mean (SD); unit micron2, 33.4 (5.61) and 110.1 (23.7), respectively. The major axes of nuclear ellipses were 7.45 (0.22) (unit micron), 7.76 (0.26), and 13.9 (1.88), respectively. The minor axes were 3.07 (0.53), 5.59 (0.95) and 10.1 (1.35), respectively. The ratios of minor axis per major axis of nuclear ellipses were 0.4 (0.57), 0.72 (0.11) and 0.73 (0.11) in zones 1, 2 and 3, respectively. These results showed that in zones 2 and 3 cell and tissue reactions were marked against rhBMP-2 implantation.

Hepatocyte growth factor suppresses vascular medial hyperplasia and matrix accumulation in advanced pulmonary hypertension of rats

BACKGROUND

Pulmonary hypertension (PH) is a progressive disease characterized by raised pulmonary vascular resistance, thought to be curable only through lung transplantation. Pathophysiologically, proliferation of pulmonary artery smooth muscle cells triggers pulmonary arterial stenosis and/or regurgitation, especially in advanced PH.

METHODS AND RESULTS

Using a rat model of advanced pulmonary vascular disease produced by injecting monocrotaline, we show that hepatocyte growth factor (HGF) targets pulmonary arterioles and blocks the progression of PH. In these rats, endogenous HGF production was dramatically downregulated during developing experimental PH, but c-Met/HGF receptor was abundant in the medial layers of pulmonary arterioles. HGF gene transfection 2 weeks after the monocrotaline injection resulted in milder medial hyperplasia in lung arterioles and inhibited overgrowth of pulmonary artery smooth muscle cells. Notably, exogenous HGF reduced lung expression levels of endothelin-1 and transforming growth factor-beta, which are critically involved in PH-linked fibrogenic events. Overall, medial wall thickening of pulmonary arteries was almost completely prevented by HGF, and the total collagen deposition in the lung decreased; both effects contributed to the suppression of pulmonary artery hypertension.

CONCLUSIONS

Our results suggest that the loss of endogenous HGF may be a feature of the pathogenesis of PH and that HGF supplementation may minimize pathological lung conditions, even advanced PH.

Isolation and characterization of a mesenchymal cell line that differentiates into osteoblasts in response to BMP-2 from calvariae of GFP transgenic mice

We established the clonal mesenchymal cell line, GFP-C3 (C3), which differentiates into osteoblasts in response to BMP-2 from calvariae of newborn green fluorescence protein (GFP) transgenic mice. This cell line cultured with control medium expressed low levels of alkaline phosphatase (ALP) activity and osterix mRNA and undetectable ALP and osteocalcin mRNA. Incubation of these cells with rhBMP-2 increased ALP activity dose-dependently and induced substantial levels of ALP, osteocalcin and osterix mRNA expression. C3 cells infected with adenovirus vector encoding BMP-2 (AdBMP-2) or Runx2 (AdRunx2) showed greatly increased ALP mRNA expression in a time-dependent fashion. Transduction with AdRunx2-induced expression of ALP and osteocalcin mRNA, but not osterix mRNA by day 3. Transduction with AdBMP-2 induced apparent expression of ALP and osterix mRNA by day 1 after transduction, but induced only weak expression of osteocalcin mRNA day 3 after transduction. Transplantation of C3 cells transduced with AdBMP-2 into back subfascia in wild-type mice with a complex of poly-d,l-lactic-co-glycolic acid/gelatin sponge (PGS) generated ectopic bone formation involving GFP-positive osteoblasts and osteocytes 2 weeks after transplantation. C3 cells transduced with AdRunx2 or AdLacZ failed to induce ectopic bone formation. Transplantation of C3 cells transduced with AdBMP-2 into craniotomy defects in wild-type mice using PGS as a carrier induced bone formation 2 weeks after transplantation, and replaced defects 4 weeks after transplantation. C3 cells transduced with AdRunx2 failed to induce bone repair after transplantation into craniotomy defects. These results indicate that C3 cells retain differentiation potential into osteoblasts in response to BMP-2. They are useful tools for analyzing the process of osteoblast differentiation in vivo after transplantation.

Recombinant hepatocyte growth factor accelerates cutaneous wound healing in a diabetic mouse model

We examined effects of recombinant hepatocyte growth factor (HGF) on cutaneous wound healing, using a full-thickness cutaneous excision model in diabetic mice. Topical administration of HGF, as well as basic fibroblast growth factor (bFGF), promoted the rate of wound closure and re-epithelialization. Both HGF and bFGF enhanced expansion of the granulation tissue and stimulated neovascularization on day 7 postwounding, wherein the increase in microvessel density in HGF-treated wounds was higher than that in bFGF-treated wounds. Matrix metalloproteinases (MMP-2 and MMP-9) activities involved in cell migration, angiogenesis, and extracellular matrix (ECM) remodeling, were enhanced by HGF-treatment on day 7. On day 28 postwounding (later stages of wound healing), granulation tissue in bFGF-treated wounds remained to a greater extent than that seen in saline- and HGF-treated wounds. Likewise, bFGF- but not HGF-treatment stimulated DNA synthesis of fibroblasts in granulation tissue, suggesting that HGF stimulates wound healing with lesser degree of susceptibility to cutaneous scarring. We propose that supplement of HGF may be a potential therapeutic approach for treatment of cutaneous ulcer.

Simple and effective osteoinductive gene therapy by local injection of a bone morphogenetic protein-2-expressing recombinant adenoviral vector and FK506 mixture in rats

We have previously utilized a human bone morphogenetic protein-2 (BMP-2)-expressing recombinant adenoviral vector (AxCAOBMP-2) for osteoinductive gene therapy in rats. However, immunosuppression is essential for osteoinduction by AxCAOBMP-2 and this is one of the major impediments to its clinical use. Injection of AxCAOBMP-2 together with the immunosuppressant FK506 made it possible to markedly reduce the dose of the immunosuppressive agent and still induce ectopic bone reliably. We injected AxCAOBMP-2 and FK506 into the right calf muscle of rats, while the same number of plaque forming units of AxCAOBMP-2 and the same dose of FK506 placebo (vehicle) were injected into the left calf muscle. At 1, 3, 5, 7, 9 days after injection, BMP-2 mRNA expression was significantly higher in the right calf muscle than in the left calf muscle. At 21 days after injection, significantly more ectopic bone was observed in the right calf muscle than in the left calf muscle. These results indicate that coinjection of FK506 significantly promotes osteoinduction. In addition, local injection of FK506 may also make it possible to prevent a decrease of gene expression with other adenoviral vector.

Counteractive effects of HGF on PDGF-induced mesangial cell proliferation in a rat model of glomerulonephritis

Activation and proliferation of glomerular mesangial cells play an important role in the development of mesangioproliferative glomerulonephritis. We investigated the role of hepatocyte growth factor (HGF) in regulating activated mesangial cell proliferation. In glomeruli of normal rats, mesangial cells barely expressed the c-Met/HGF receptor. However, when mesangioproliferative glomerulonephritis was induced in rats by the administration of an anti-Thy 1.1 antibody, glomerular HGF expression transiently decreased along with mesangiolysis, and activation of mesangial cells was associated with upregulation of the c-Met receptor. Activated mesangial cells in culture also expressed the c-Met/HGF receptor. Although addition of HGF to cultured mesangial cells did not increase DNA synthesis, HGF did diminish PDGF-induced DNA synthesis. PDGF induced activation of ERK, which continued for at least 48 h. When PDGF and HGF were simultaneously added, HGF inhibited the prolonged activation of ERK, which suggests that early inactivation of PDGF-induced ERK may be involved in the inhibitory effect of HGF on mesangial cell proliferation. Furthermore, administration of HGF to rats with anti-Thy 1.1 nephritis resulted in a selective suppression of activated mesangial cell proliferation, and this suppressive effect was associated with attenuation of phosphorylated glomerular ERK. These results indicate that HGF counteracts PDGF-induced mesangial cell proliferation and functions as a negative regulator of activated mesangial cell proliferation.

Preclinical study of recombinant human bone morphogenetic protein-2: application of hyperbaric oxygenation during bone formation under unfavourable condition

The objective of this study was to evaluate the effect of hyperbaric oxygenation on bone formation by recombinant human bone morphogenetic protein-2 (rhBMP-2) under unfavourable conditions. The calf muscles of 10 rats with low-blood supply were prepared by ligating and cutting the right femoral artery, and 10 micro of rhBMP-2 was implanted in the calf muscle. Five rats each were randomly assigned to the hyperbaric oxygenation group and the control group (untreated). The rats in the hyperbaric oxygenation group were treated with hyperbaric oxygenation at 2.0 atmospheres absolute for 3 weeks. In the histologic evaluation, the number of osteoblasts in the hyperbaric oxygenation group was greater than that in control group. The area of the trabecular bone induced in the hyperbaric oxygenation group was significantly larger than that in the control group. The values of alkaline phosphatase activity and calcium contents in the hyperbaric oxygenation group were significantly higher than those in the control group. The results of the present study suggest that hyperbaric oxygenation increases the partial oxygen pressure in low blood supply tissue and accelerates the activity and rate of osteoinduction by rhBMP-2. Hyperbaric oxygenation therapy may increase the clinical application of rhBMP-2 to unfavourable condition.

Transplantation of skin fibroblasts expressing BMP-2 promotes bone repair more effectively than those expressing Runx2

We investigated the osteogenic potential of skin fibroblasts that overexpressed BMP-2 or Runx2 by using adenoviral vectors. In in vitro experiments, skin fibroblasts infected with adenovirus vector encoding BMP-2 (AdBMP-2) released substantial levels of BMP-2 proteins into culture media, and those infected with adenovirus vector encoding Runx2 (AdRunx2) produced its protein. Transduction of BMP-2 or Runx2, respectively, increased alkaline phosphatase (ALP) activity and induced expression of mRNAs of ALP, osteocalcin, and osterix in skin fibroblasts. In in vivo experiments, we investigated the bone induction activity by transplantation of a complex composed of carrier [poly-D,L-lactic-co-glycolic acid/gelatin sponge (PGS)] and skin fibroblasts (PGS/SF complex). Transplantation of PGS/SF complexes composed of skin fibroblasts transduced with AdBMP-2-induced ectopic bone formation when transplanted into the subfascia of back muscle, unlike those infected with AdRunx2. Transplantation of PGS/SF complexes composed of skin fibroblasts transduced with AdBMP-2 into craniotomy defects induced bone formation from 2 weeks after transplantation, and almost all PGS was replaced by newly synthesized bone at 6 weeks. To investigate the fate of the transplanted cells, we transplanted skin fibroblasts isolated from green fluorescence protein transgenic mice into craniotomy defects. Transplantation of these skin fibroblasts transfected with AdBMP-2 generated green fluorescence protein-positive osteoblasts and osteocytes, indicating that the transplanted skin fibroblasts differentiated into osteoblastic lineage cells during bone repair. In contrast, transplantation of PGS/SF complexes composed of skin fibroblasts transduced with AdRunx2 induced a few ALP-positive cells at 1 week after transplantation, but their number decreased depending on time after transplantation. In addition, transplantation of these complexes was insufficient to induce bone repair. Taken together, our results suggest that skin fibroblasts expressing BMP-2 are more suitable for cell-mediated therapy of bone repair than those expressing Runx2.

Experimental studies on bone induction using low-molecular-weight poly (DL-lactide-co-glycolide) as a carrier for recombinant human bone morphogenetic protein-2

An appropriate carrier acting as a slow delivery vehicle for the BMPs is required for maximal clinical effectiveness of these bone-inductive proteins. The purpose of this study was to evaluate a low-molecular-weight PLGA copolymer as a synthetic, biodegradable carrier for rhBMP-2 implantation in vivo. Two, 10, or 50 microg of recombinant human BMP-2 were mixed with 10 mg of a poly (DL-lactide-co-glycolide) (PLGA) 50:50 copolymer and implanted into the calf muscles of Wistar rats. Soft X-ray analysis and histologic examination indicated that new bone formation occurred at all rhBMP-2-implanted sites within 3 weeks after implantation. Correlation of rhBMP-2 concentration with the amount of bone induction was confirmed by specific alkaline phosphatase activity and calcium content assay. In vitro analysis indicated that 78.5% of the PLGA copolymer was degraded to smaller molecular weight material after 14 days in PBS solution. It is suggested that rhBMP-2 was released in an active form at the implant site during the degradation of the copolymer, resulting in the induction of new bone formation. Thus this low-molecular-weight PLGA copolymer material represents a promising delivery vehicle for BMPs, and possibly other growth factors, around dental and orthopedic implants.

Regeneration of defects in the articular cartilage in rabbit temporomandibular joints by bone morphogenetic protein-2

The purpose of this study was to investigate the therapeutic use of recombinant human bone morphogenetic protein-2 (rhBMP-2) in internally deranged temporomandibular joints (TMJ). Defects (2 mm in diameter) were created in the surface of the condylar head. Lyophilized rhBMP-2 with collagen as the carrier was implanted in the defects in different doses: rhBMP-2 15 microg (n = 5); rhBMP-2 3 microg (n = 5); rhBMP-2 0.6 microg (n = 5). In the two control groups, the defects were either filled with collagen alone (n = 5) or left untreated (n = 5). Three weeks postoperatively the sites of defects were examined under light microscopy. In the 15 micromg and the 3 microg groups, new cartilage had filled the defects; endochondral ossification was also found deep within the defect. In the 0.6 microg group, fibrous tissue was proliferating in most areas of the defect, although cartilage was also found in some parts. In the two control groups, there was either soft tissue repair only or no evidence of tissue repair. These findings suggest that BMP-2 could stimulate the repair of defects in the articular cartilage of the mandibular condyle head during the 3 weeks postoperatively. To observe the progress of endochondral ossification in more detail, it may be necessary to extend the experiment for a longer period of time. However, this study supports the contention that BMP-2 may be useful in the regeneration of cartilage in TMJ disease.

Osteoinduction by recombinant human bone morphogenetic protein-2 in muscles of non-human primates

Heterotopic osteoinduction in a muscle of a medium-sized, non-human primate (Japanese macaque monkey; Macaca fuscata) was investigated with recombinant human bone morphogenetic protein-2 (rhBMP-2) mixed with atelopeptide type I collagen as the carrier. Nine monkeys were divided into three groups of three: groups I (1.25 mg rhBMP-2), II (250 micrograms rhBMP-2) and III (50 micrograms rhBMP-2). Four weeks after implanting into the calf muscle pouch, the implant was examined radiographically and histologically. In one specimen of three in group I, marked radio-opaque shadow, massive chondrogenesis and partial osteogenesis were observed. In the other two specimens, only microscopic calcification signs were recognized. In groups II and III, no findings of heterotopic osteoinduction were radiographically observed; however, nuclei from muscle bundles reacted to rhBMP-2 and were large and round, as in muscle bundles near the site of osteogenesis in group I. A positive control study using rats was carried out in parallel. This was a dose-finding study, with the monkeys in group III acting as a sub-effective dose (placebo) control, and rats acting as an active control, or verum, to show that the techniques are sufficiently sensitive. Bone morphogenetic protein appears to osteoinduce less bony material in soft tissue in primates than in rats.

Bone response to radio frequency sputtered calcium phosphate implants and titanium implants in vivo

The objective of this study was to evaluate the effect of radio frequency sputtered calcium phosphate (CaP) coatings of titanium (Ti) implants on the bond strength at the bone-implant interface and percent bone contact length. Cylindrical coated or noncoated implants (4.0-mm diameter by 8-mm long) were implanted for 3 and 12 weeks. At 3 weeks after implant placement, the ultimate interfacial strengths for as-deposited CaP-coated and heat-treated CaP-coated implants were 2.29 +/- 0.14 MPa and 1.28 +/- 0.04 MPa, respectively. These ultimate interfacial strength values at 3 weeks were statistically greater than the mean ultimate interfacial strength for control Ti implants (0.67 +/- 0.13 MPa). At 12 weeks after implant placement, no statistical differences in the mean ultimate interfacial strengths were observed between the as-deposited CaP-coated, heat-treated CaP-coated, and control Ti implants. Histomorphometric evaluation indicated greater percent bone contact lengths for the as-deposited CaP-coated implants compared with the heat-treated CaP-coated and control Ti implants 3 and 12 weeks after implant placement.

The time course study of osteoinduction by bone morphogenetic protein-2 via adenoviral vector

We evaluated the time course of osteoinduction by an adenoviral vector, AxCAOBMP-2, in normal rats (Group I) and 2 immunosuppressed groups (Groups II and III). Immunosuppression was induced by 125 mg/kg of cyclophosphamide injected intraperitoneally the day before vector injection. Groups I and III received a high dose of AxCAOBMP-2 (25 microl; 8.75 x 10(8) pfu) and Group II a low dose (5 microl; 1.75 x 10(8) pfu). Each dose of AxCAOBMP-2 was injected into the right calf muscle of rats. On days 7, 14 and 21 postinjection, the osteoinducive activity in each group was investigated radiologically, histologically, immunohistochemically and biochemically. Osteoinduction was observed only in Groups II and III on days 14 and 21. The activity of osteoinduction in Group III was higher than that in Group II. There was little difference in the expression of LacZ between Groups I and III on day 3. However, there was a marked difference in BMP-2 protein expression between Groups I and III on day 7 postinjection. We speculated that the reason for this was that most of the infected cells were eliminated by the immune system of the host from days 3 to 7. These results suggest that gene therapy with AxCAOBMP-2 under transient immunosuppression may be useful for bone reconstruction.

Immunohistochemical localization of bone morphogenetic protein-2 in the oral and maxillofacial area of the human embryo

The purpose of this study was to investigate the bone morphogenetic protein-2 (BMP-2) expression in oral and maxillofacial tissue of the human embryo. A human embryo was obtained from a patient with hysterorrhexis. The oral and maxillofacial area of the embryo was analyzed immunohistochemically using specific antibodies to BMP-2. BMP-2 was found mainly localized in developing teeth buds, jaw bone, striated and smooth muscle, spinal cord and nasal tracheal and oesophagal epithelium. However, it was not found in hair follicles. These findings are similar to those of BMP-2 and -4 gene expression in mouse and rat embryos. BMP-2 may be involved in the morphogenesis of oral and maxillofacial tissue in human embryos as well as those of other animals. These results will be of considerable benefit in the restoration and regeneration of the oral and maxillofacial tissue clinically.

Experimental osteoinduction by recombinant human bone morphogeneticprotein 2 in tissue with low blood flow: a study in rats

We have compared osteoinduction in soft tissues by 0, 2, 10, and 50 microg of recombinant human bone morphogenetic protein-2 (rhBMP-2) in Wistar rats with a surgically compromised blood supply and controls with a normal blood supply (n = 5 in each group). Three weeks later in the radiographic evaluation, the volume of bone formation in the low-blood-flow groups was similar to that in the controls, and was dependent on the concentration of implanted rhBMP-2. On histological evaluation much woven bone was noted in the low-blood-flow groups, but the volume of bone was less than in the controls. Alkaline phosphatase activity was less and calcium content in the low-blood-flow groups were also less than in the control rats. However, their values increased dose-dependently with implanted rhBMP-2. These results suggest that the osteoinducting activity of rhBMP-2 is reduced in tissues with a low blood supply, but higher doses of rhBMP-2 can be used in compromised tissue.

In vitro and in vivo studies of a bone morphogenetic protein-2 expressing adenoviral vector

BACKGROUND

Bone morphogenetic proteins (BMPs) play important roles in the migration of osteoblast progenitor cells, the proliferation of mesenchymal cells, and their differentiation into chondrogenic and osteogenic cells. However, the optimum procedure to deliver BMPs remains unknown. To examine the effectiveness of a gene transfer procedure for the delivery of BMP-2, we constructed a human BMP-2-expressing replication-deficient adenoviral vector, AxCAOBMP-2, and evaluated its osteoinductive activity in vitro and in vivo.

METHODS

C2C12 myoblasts were infected in vitro with this viral vector or an Escherichia coli LacZ gene-expressing control adenovirus vector (AxCALacZ). Twenty-four hours after the infection, indirect immunofluorescence was performed. On day 5 after the infection, alkaline phosphatase (ALP) in the cells and osteocalcin in the culture medium were measured. Furthermore, to examine the effectiveness of gene transfer of BMP-2 in vivo, we evaluated osteoinduction by AxCAOBMP-2, under transient immunosuppression with cyclophosphamide, given at a dose of 125 mg/kg intraperitoneally the day before injection of the adenoviral vector. Twenty-five microliters of AxCAOBMP-2 (8.75 x 10(8) plaque-forming units [pfu], Group I) and AxCALacZ (1.75 x 10(8) pfu, control group) and 5 microl of AxCAOBMP-2 (1.75 x 10(8) pfu, Group II) were injected into a right calf muscle of Wistar rats. On day 21, bone formation in each group was investigated radiologically and histologically.

RESULTS

Abundant BMP-2 expression in C2C12 cells infected with this viral vector was confirmed by immunofluorescence. C2C12 cells transferred with the BMP-2 gene by this vector produced ALP in the cells and also produced and secreted osteocalcin in the culture medium. Osteoinduction was found only in the AxCAOBMP-2 treated groups with immunosuppression. Osteoinduction activity was higher in Group I than in Group II.

CONCLUSION

This study demonstrated the osteoinductive activity in vitro and in vivo by an adenoviral vector carrying the BMP-2 gene.

CLINICAL RELEVANCE

Gene therapy with AxCAOBMP-2 under transient immunosuppression may be useful for bone reconstruction.

Bone morphogenetic protein-2 and type IV collagen expression in psammoma body forming ovarian cancer

Psammoma bodies (PBs), characterized as calco-spherules with concentric laminations, are common in serous tumors of the ovary. However, there is no agreements as to how the PBs are formed. Bone morphogenetic protein-2 (BMP-2) has recently been proposed to be involved in the calcification of tumor cells and recent electron microscopic studies demonstrated the presence of type IV collagen in PBs. Based on this evidence, we postulated a possibe role for BMP-2 and type IV collagen in the formation of PBs in ovarian cancer. We examined the expression of BMP-2 and typle IV collagen by immunohistochemistry and reverse transcription PCR (RT-PCR) in PBs-forming (NK-211) and -non-forming (SHIN-3, KF-1, A2780, KK-92, KOC-2S, SKOV-3, OMC-3, MN-1, EC, and KEN-3) ovarian cancer cell lines in vitro and in surgical specimens of serous adenocarcinoma (SA) with/without PBs and mucinous adenocarcinoma (MA) of the ovary. Cellular growth of cell lines was also evaluated by their doubling time in vitro. Transcripts for BMP-2 mRNA were detected by RT-PCR in all cell lines. By immunohistochemistry, BMP-2 protein expression was positive in 45% (5 out of 11) of cell lines. 36.4% (4 out of 11) were positive for type IV collagen. PBs-forming NK-211 was intensively positive for both BMP-2 and type IV collagen. In addition, NK-211 demonstrated extremely slow growth with a doubling time of 450 hours. In surgical specimens, BMP-2 vs. type IV collagen positivities in tumor cells were 100% (20 out of 20) vs. 40% (8 out of 20) in SA with PBs, 61.1% (11 out of 18) vs. 0% (0 out of 18) in SA without PBs and 75% (9 out of 12) vs. 0% (0 out of 12) in MA. In PBs themselves, 100% (20 out of 20) positivity for BMP-2 and 80% (16 out of 20) for type IV collagen was shown. These results raise the possibility that BMP-2 and type IV collagen-producing slow growing tumor cells form PBs in ovarian cancer.

Effects of high ELF magnetic fields on enzyme-catalyzed DNA and RNA synthesis in vitro and on a cell-free DNA mismatch repair

Environmental electromagnetic fields have been implicated in human cancers. We examined whether high extremely low frequency (ELF) AC magnetic fields could affect DNA synthesis, transcription or repair, using in vitro model systems with defined sequences. The rate and fidelity of DNA polymerase catalyzed DNA synthesis, as well as of RNA polymerase catalyzed RNA synthesis, were not statistically significantly affected by 60 Hz 0.25-0.5 Tesla magnetic fields. The efficiency of mutS dependent mismatch repair with human cell extracts was also not affected by the magnetic field exposure. The results suggest that the core processes related to the transmission of genetic information are stable under high ELF magnetic fields.

Effect of hyperbaric oxygenation on bone induced by recombinant human bone morphogenetic protein-2

We examined the effect of hyperbaric oxygen (HBO) therapy on the osteoinductive activity of recombinant human bone morphogenetic protein-2 (rhBMP-2), 5mg of which was implanted into the calf muscle of rats using atelopeptide type I collagen as a carrier. Thirty Wistar rats were divided equally to be given HBO or act as controls. New bone formation was measured radiographically, biochemically, and histol ogically 3, 7, and 21 days after implantation. In both groups, new bone formation was found on day 21. However, there was significantly more new bone in the HBO group. In the HBO group, cartilage was present at the outer edge of the implanted material on day 7. On days 7 and 21, the local tissue alkaline phosphatase activity and calcium content in the HBO group were significantly greater than in the control group. These results suggest that HBO accelerated the activity and rate of osteoinduction by rhBM P-2.

Bone induction by Escherichia coli -derived recombinant human bone morphogenetic protein-2 compared with Chinese hamster ovary cell-derived recombinant human bone morphogenetic protein-2

Most recombinant human bone morphogenetic protein (rhBMP) is currently obtained from Chinese hamster ovary (CHO) cells. If rhBMP with more activity could be derived from Escherichia coli (E. coli), a large quantity of rhBMP could be produced at low cost. The bone-inducing ability of an E. coli -derived rhBMP-2 (ErhBMP-2) variant with an N-terminal sequence was examined and compared with CHO cell-derived rhBMP-2 (CrhBMP-2). Two, 10, or 50 microgram of ErhBMP-2 or CrhBMP-2 was mixed with 3mg of atelopeptide type I collagen as the carrier, and specimens were implanted into the calf muscle pouches of Wistar rats (n= 5 in each group). Three weeks later, new bone had formed in all the ErhBMP-2-implanted and CrhBMP-2-implanted muscles. Radiographic and histological examinations showed that the bone induced by ErhBMP-2 had a large hollow bone matrix with more fatty marrow than the bone induced by CrhBMP-2. Quantitative analysis indicated that the activity of ErhBMP-2 was similar to that of CrhBMP-2, so ErhBMP-2 may be useful for inducing bone formation.

Immunohistochemical expression of bone morphogenetic protein-2 in pilomatricoma

BACKGROUND

The mechanism of occurrence of calcification and ossification in pilomatricoma remains unclear.

OBJECTIVES

To elucidate the pathogenesis of calcification and ossification in pilomatricoma we examined the role of bone morphogenetic protein (BMP)-2, which plays important parts in inducing ectopic bone formation both in vivo and in vitro.

METHODS

Twenty cases of pilomatricoma were studied immunohistochemically using anti-BMP-2 monoclonal antibody.

RESULTS

In normal skin, including hair follicles, there was no BMP-2 expression. In all pilomatricomas, BMP-2 was found exclusively in the cytoplasm of shadow cells but not in basophilic cells. In two cases of bone formation seen in pilomatricoma, osteoblasts in the periosteal area showed a strong positive reaction, while bone trabeculum (bone matrix) showed no reaction.

CONCLUSIONS

Our findings indicate that shadow cells positive for BMP-2 may play an important part in generating bone formation in pilomatricoma.

The effect of blood supply in muscle and an elevated muscle flap on endogenous tissue-engineered bone by rhBMP-2 in the rat

Metabolism and remodeling of bony tissue are maintained and controlled by blood supply. In this study, bony tissue osteoinduced heterotopically by recombinant human bone morphogenetic protein-2 (rhBMP-2) in rat muscles with different amounts of blood supply was investigated. The implant beds were in the latissimus dorsi muscle (LDM) and in the space wrapped with an elevated latissimus dorsi muscle flap (LDMF). The blood flow was preestimated at two muscle sites using a laser Doppler blood flowmeter. The flow value of the LDM was 2.23 +/- 0.17 ml/min/100 g (mean +/- standard deviation). The flow values of the LDMF were 1.71 +/- 0.22 ml/min/100 g 30 minutes after elevating the LDMF, 1.75 +/- 0.20 ml/min/100 g after 1 week, 1.83 +/- 0.19 ml/min/100 g after 2 weeks, and 1.99 +/- 0.18 ml/min/100 g after 3 weeks. Bony tissues induced heterotopically by rhBMP-2 were examined radiographically and histologically. On radiographs, radiopaque shadows in the LDM were almost as large as those in the LDMF. The radiopacity in the LDM was a little higher than that of the LDMF. The microscopic findings showed increased trabeculae and more hematopoietic marrow in the LDM than lamellalike bone in the LDMF. Mean bony area in the implant was 1.05 +/- 0.26 mm2 in the LDM, and was 0.70 +/- 0.11 mm2 in the LDMF. Bony proportions in the overall implant area were 18.3 +/- 3.46% in the LDF and 12.1 +/- 2.18% in the LDMF. The current study indicates that blood supply is an important factor for promoting heterotopic osteoinduction by rhBMP-2 to produce massive bony tissue as an endogenous method of tissue engineering.

Osteogenesis by recombinant human bone morphogenetic protein-2 at skeletal sites

Osteogenesis was evaluated in the mandibular bone by combinations of various dosages of recombinant human bone morphogenetic protein-2, atelopeptide Type I collagen, and porous hydroxyapatite (four groups: Group I, 2 micrograms recombinant human bone morphogenetic protein-2, atelopeptide Type I collagen, and porous hydroxyapatite; Group II, 10 micrograms recombinant human bone morphogenetic protein-2, atelopeptide Type I collagen, and porous hydroxyapatite; Group III, 50 micrograms recombinant human bone morphogenetic protein-2, atelopeptide Type I collagen, and porous hydroxyapatite; Control Group, only atelopeptide Type I collagen and porous hydroxyapatite). The prepared materials were implanted in the mandibular bone hole (7 mm in diameter, 2 mm deep). Three weeks later, the alkaline phosphatase activity in the implanted region was determined, and the histologic features of the excised tissue were examined. There were significant differences in histologic and biochemical findings among the four groups. In the recombinant human bone morphogenetic protein-2 implanted groups, osteogenesis increased with the dosage of recombinant human bone morphogenetic protein-2, as assessed by alkaline phosphatase activity and histologic findings. The results suggest that atelopeptide Type I collagen is an effective carrier for recombinant human bone morphogenetic protein-2 and that porous hydroxyapatite would be advantageous for clinical application as a material to maintain its original form after implantation.

Effect of elcatonin on osteoinduction by recombinant human bone morphogenetic protein-2

To evaluate the effect of elcatonin on osteoinduction by recombinant human bone morphogenetic protein-2 (rhBMP-2), 5 microg of rhBMP-2 was implanted into intramuscular sites of rats. For 14 days after the implantation, elcatonin was administered intraperitoneally with total dosage of 80 U, 8 U, and 0.8 U, respectively. For the control group, only physiological saline was administered. At 21 days after implantation, the area of the oval shadow in the radiologic findings depended on the elcatonin dose and the amount of trabecular bone and the number of osteoblasts observed in the histologic findings depended on the dosage of elcatonin. The values of ALP activity and Ca content also showed an elcatonin dose dependency. These results suggested that elcatonin is effective in enhancing osteoinduction by rhBMP-2 within the dose range of this study, and that elcatonin has an anabolic effect on osteoblasts in addition to an antiresorptive effect.

Effect of protein on the dissolution of HA coatings

The dissolution behavior of hydroxyapatite (HA) in the presence and absence of protein needs to be investigated in order to fully understand the initial cellular response to HA surfaces. In this study, HA coatings were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy (FTIR) prior to protein study. Fibronectin and albumin adsorption study were also performed. Calcium and phosphorus released in the presence and absence of albumin were measured. pH of the solution was measured daily. From the materials characterization, it was observed that the coatings exhibit a HA-type structure, with traces of sodium on the surface. FTIR indicated the possible presence of carbonates on the coatings. From the adsorption study, the amount of albumin adsorbed (0.052+/-0.005 microg/mm2) was statistically higher than the amount of fibronectin adsorbed on HA surfaces (0.035+/-0.002 microg/mm2). Flame atomic absorption indicated a significantly higher calcium ions released initially for HA coatings incubated with proteins as compared to coatings in the absence of proteins. However, after 7 days incubation, no significant difference in calcium ions release was observed between the HA coatings in the presence and absence of proteins. Phosphorus dissolution on HA coatings was not significantly affected by the presence of proteins. Thus, it was suggested from this study that the initial dissolution properties of calcium ions from HA coatings was dependent on the media.

Osteoinduction by recombinant human bone morphogenetic protein-2 at intramuscular, intermuscular, subcutaneous and intrafatty sites

To compare the osteoinductive activity of recombinant human bone morphogenetic protein-2 (rhBMP-2) at various sites in rats, 5 microg of rhBMP-2 were implanted into various sites, using atelopeptide type-I collagen (CL) as a carrier (BMP groups). CL implantation was used as a control. Forty Wistar rats were divided into intramuscular, intermuscular, subcutaneous and intrafatty site groups (IrM, IeM, SC and IF, respectively). Bone formation was evaluated radiographically, histologically and biochemically 21 days after implantation. In the BMP groups, the alkaline phosphatase activity and calcium content at all sites were higher than those in the control groups. Among the BMP groups, the new bone formation was highest in the IrM and lowest in the IF radiographically, histologically and biochemically. Five microg of rhBMP-2, a relatively low dose, induced adequate new bone formation in all sites. The variations of osteoinductive activity of rhBMP-2 in various sites may be due to differences in the blood supply.

Osteoinduction by bone morphogenetic protein-2 via adenoviral vector under transient immunosuppression

To examine the effectiveness of gene transfer of bone morphogenetic protein (BMP)-2 in vivo, we evaluated osteoinduction by an adenoviral vector, AxCAOBMP-2, under transient immunosuppression with an immunosuppression drug (cyclophosphamide), which was given at a dose of 125 mg/kg intraperitoneally the day before vector injection. Twenty-five microliters of AxCAOBMP-2 (8.75 x 10(8) pfu, Group I) and AxCALacZ (1.75 x 10(8) pfu, control group) and 5 microliter of AxCAOBMP-2 (1.75 x 10(8) pfu, Group II) were injected into a right calf muscle. On day 21, induced bone in each group was investigated radiologically, histologically, and biochemically. The finding of osteoinduction was only seen in the AxCAOBMP-2-treated groups with immunosuppression. The activity of osteoinduction in Group I was higher than that in Group II. These results suggest that gene therapy with AxCAOBMP-2 under transient immunosuppression may be useful for bone reconstruction.

Bone morphogenetic protein-2 in temporomandibular joints with internal derangement

OBJECTIVE

The purpose of this study was to analyze the expression of bone morphogenetic protein-2 (BMP-2) in patients with internal derangement of the temporomandibular joint.

STUDY DESIGN

Twenty-one human temporomandibular joint samples (5 extirpated disks and 16 biopsy specimens of synovitis area from patients with internal derangement of the TMJ) and 2 control temporomandibular joint specimens (2 normal disks obtained by autopsy) were analyzed with specific antibodies through use of an immunohistochemical technique.

RESULTS

BMP-2 was predominantly localized in chondrocytes around the damaged areas of the articular disks. BMP-2 expression was also found in synovial cells and endothelial cells of blood vessels. Control specimens demonstrated BMP-2 staining in synovial lining cells and endothelial cells of blood vessels. However, the chondrocytes in the normal cartilage layers of the control specimens showed no staining.

CONCLUSIONS

These findings suggest that BMP-2 may be involved in the pathogenesis of osteoarthritic changes or the repair process of temporomandibular joint internal derangement.

Osteoblast progenitor cell responses to characterized titanium surfaces in the presence of bone morphogenetic protein-atelopeptide type I collagen in vitro

The goal of this study was to investigate the effect of bone cell response to titanium (Ti) surfaces in the presence of bone morphogenetic protein (BMP)-atelopeptide type I collagen mixture. The atelopeptide type I collagen was used as a potential carrier for the BMP. Sterilized 600-grit Ti samples were used as substrates for the cell culture study. X-ray photoelectron spectroscopy indicated the presence of TiO2 on the Ti surface. The in vitro cell culture study was performed using an osteoblast progenitor cell line derived from mice (2T9). At confluency, the cells cultured on Ti surfaces were divided into three groups: unstimulated culture, culture stimulated by BMP-atelopeptide type I collagen (40 ng/mL), and culture stimulated by atelopeptide type I collagen (40 ng/mL). The unstimulated and atelopeptide type I collagen cultures were controls in this study. After 4 days of incubation, protein production, alkaline phosphatase (ALP) activity, and hexosaminidase activity were observed to be the highest for cells exposed to the BMP-atelopeptide type I collagen mixture. Statistical differences in cellular protein production and ALP activity were observed between the controls and the surfaces exposed to the BMP-atelopeptide type I collagen mixture. Similarly, a statistical difference in hexosaminidase activity was observed between unstimulated Ti surfaces and surfaces exposed to BMP-atelopeptide type I collagen mixture. However, no statistical differences in protein production, ALP activity, and hexosaminidase activity were observed between cells exposed to atelopeptide type I collagen solution and the unstimulated surfaces.

Expression of bone morphogenetic protein-2 via adenoviral vector in C2C12 myoblasts induces differentiation into the osteoblast lineage

To examine the effectiveness of a gene transfer of bone morphogenetic protein (BMP)-2 into C2C12 myoblasts, we constructed a human BMP-2-expressing replication-deficient adenoviral vector, AxCAOBMP-2. C2C12 cells were infected in vitro with either this viral vector or an Escherichia coli LacZ gene-expressing control adenovirus vector. An efficient gene transfer to the C2C12 cells was confirmed with the LacZ gene-expressing vector by X-gal staining. Abundant BMP-2 expression in C2C12 cells infected with this viral vector was confirmed by immunofluorescence and Western blot analysis. C2C12 cells transferred with the BMP-2 gene by this vector produced alkaline phosphatase in the cells and also produced and secreted osteocalcin in the culture medium, demonstrating that a gene transfer of BMP-2 into C2C12 cells in vitro could convert these cells from myoblast to osteoblast lineage.