Tissue engineering for bone regeneration: stem cells and growth factors in biomaterial scaffolds.

Background: Bone tissue engineering requires a scaffold conducive to cell attachment and maintenance of cell function, together with a rich source of osteoprogenitor cells in combination with osteoinductive growth factors. Bone loss as a result of trauma or disease is an increasingly serious health problem. The requirement for new bone to replace or restore the function of injured, damaged, or lost bone is a major clinical and socioeconomic need. Bone defects still represent a major challenge for orthopaedic and reconstructive surgeons. Objective: This review aims at outlining the role of stem cells and growth factors in scaffolds, focusing on the use of mesenchymal stem cells and bone morphogenetic proteins as applied to the research and practice of bone tissue engineering. Results and conclusion: Bone tissue engineering has been emerging as a valid approach to the current therapies for bone regeneration. Therefore, tissue engineering offers a number of possible strategies to the generation of living prosthesis that could integrate with host tissue reducing the need for further surgery or possible implant failure.

Analysis of connective tissue growth factor promoter polymorphism in Thai children with biliary atresia.

OBJECTIVE: Connective tissue growth factor (CTGF) has been proposed to play a key role in the pathogenesis of hepatic fibrosis in biliary atresia (BA). The aim of the present study was to determine the single nucleotide polymorphism (SNP) in the promoter region of CTGF gene in a Thai population, and to investigate the possible role of CTGF promoter polymorphism in the susceptibility of BA. MATERIAL AND METHOD: Genomic DNA was obtained from 84 patients with BA and 142 healthy controls. The -447 G/C and -132 C/G in CTGF promoter were amplified and examined by amplification-refractory mutation system (ARMs) and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis, respectively. The test of Hardy-Weinberg equilibrium (HWE) was performed using HWE program of SNPAnalyzer. Statistical analysis was carried out with SPSS and Epi Info. RESULT: According to the previous experiment, there were two SNPs, which were at position -447 and -132 on the promoter. However, there was only one SNP at the position -447 in the Thai population. No significant differences in genotype and allele frequency were observed between BA and controls or with BA subgroups. CONCLUSION: The present study demonstrated that CTGF polymorphism at -447 G/C was not associated with BA and the jaundice status of the postoperative BA patients.

Association of serum levels of tissue inhibitors of metalloproteinase-1 with clinical outcome in children with biliary atresia.

The purpose of this study was to determine the possible role of serum levels of tissue inhibitors of metalloproteinase-1 (TIMP-1) in the pathogenesis of the progressive inflammation and fibrosis in biliary atresia (BA). Serum concentrations of TIMP-1 were measured in 57 BA patients and 15 healthy controls using commercially available enzyme-linked immunosorbent assays. The mean ages of the BA patients and the controls were 6.1 +/- 0.6 and 6.7 +/- 1.1 years, respectively. The patients were categorized into two groups according to their clinical outcomes: patients with jaundice (total bilirubin > or = 2 mg/dl) and patients without jaundice (total bilirubin < 2 mg/dl). In our study, serum levels of TIMP-1 were significantly higher in the BA patients than in healthy subjects (4.8 +/- 0.4 vs. 3.5 +/- 0.3 ng/ml, respectively; p < 0.05). Additionally, serum levels of TIMP-1 significantly increased in the BA patients with jaundice in comparison to those without jaundice (6.3 +/- 0.7 vs. 3.1 +/- 0.3 ng/ml, respectively; p = 0.001). Patients with persistent jaundice had lower levels of albumin but had greater levels of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, and gamma glutamyl transpeptidase compared with patients without jaundice. Furthermore, patients with portal hypertension (PH) had higher TIMP-1 levels than those without PH (5.3 +/- 0.4 vs. 1.9 +/- 0.3 ng/ml, respectively; p < 0.001). It is concluded that serum levels of TIMP-1 increased in patients with BA. The significant increase in TIMP-1 levels is related to the presence of PH and the severity of jaundice. The elevated TIMP-1 levels may reflect the degree of hepatic fibrosis and development of PH. The data suggest that TIMP-1 may play a role in the pathophysiology of post-Kasai BA.

Effects of demineralized bone matrix on proliferation and osteogenic differentiation of mesenchymal stem cells from human umbilical cord.

BACKGROUND: Mesenchymal stem cells or mesenchymal progenitor cells are defined as self-renewable, multipotent progenitor cells with the unlimited capacity to differentiate into multiple lineage-specific cells that form bone, cartilage, fat, and muscle tissues. Demineralized bone matrix (DBM) has been extensively utilized in orthopaedic, periodontal, and maxillofacial applications and widely investigated as a biomaterial to promote new bone formation. OBJECTIVE: To isolate and characterize umbilical cord mesenchymal stem (UCMS) cells and examine the biological activity of DBM in the UCMS cells MATERIAL AND METHOD: UCMS cells were obtained from human umbilical cord culture. Cells were treated with or without DBM over 7 days of culture. Cell proliferation was examined by direct cell counting. Osteogenic differentiation of the UCMS cells was analysed with alkaline phosphatase staining assay. RESULTS: Phenotypic characteristics ofhuman UCMS cells were spindle and stellate shapes with fine homogenous cytoplasm, typically associated with fibroblast-like cells. The control cells (without DBM treatment) exhibited a spindle shape with little extracellular matrix, whereas the DBM treated cells appeared shortened and flattened, and they were surrounded by extracellular matrix. DBM inhibited the growth of the UCMS cells by 50%, as determined by direct cell counting. Morphologic and histochemical studies confirmed that DBM had a strong stimulatory effect on the alkaline phosphatase activities of UCMS cells, a very early marker of cell differentiation into the osteogenic lineage. CONCLUSION: Mesenchymal progenitor cells derived from umbilical cord could differentiate along an osteogenic lineage and thus provide an alternative source for cell-based therapies and tissue engineering strategies.

Content of bone morphogenetic protein-4 in human demineralized bone: relationship to donor age and ability to induce new bone formation.

BACKGROUND: Bone morphogenetic proteins (BMPs) are also called growth and differentiation factors (GDFs) and form a subfamily of related proteins within the TGF-beta superfamily. BMP-4 is one ofmultifuntional growth factors with pleiotropic roles in many different cell types and is predominantly present in human bone tissue. OBJECTIVES: To analyze the content of extractable BMP-4 in human demineralized bone as a function of age. MATERIAL AND METHOD: Bone samples were ground and demineralized by exposure to 0.5 N HCl and then extracted by collagenase digestion. Extractable BMP-4 was analyzed using a commercially available enzyme-linked immunosorbent assay (ELISA). RESULTS: 63 samples of demineralized bone matrix (DBM) derived from 36 men and 27 women between the ages of 15-65 years. The extractable BMP-4 content appears to be age-dependent, with DBM from younger donors being most likely to have higher BMP-4 quantity. In addition, DBM with high osteoinductivity contained greater amounts of extractable BMP-4 than DBM samples with low osteoinductivity. CONCLUSION: The BMP-4 in demineralized bone undergoes age-related decrease that may contribute to the reduction of bone volume observed with aging.