Modulation of Cell Attachment, Proliferation, and Angiogenesis by Decellularized, Dehydrated Human Amniotic Membrane in In Vitro Models.

Background: Decellularized, dehydrated human amniotic membrane (DDHAM) is an extracellular matrix devoid of cells, cell debris, and growth factors. This study examines the effect of cell attachment to the DDHAM and the induced cellular responses.

Materials And Methods: The cell types employed in this study were human dermal fibroblasts (HDF), human epithelial keratinocytes (HEK), and human dermal microvascular endothelial cells (HDMEC), all of which play critical roles in the wound healing process.

Glycogen synthase kinase-3α limits ischemic injury, cardiac rupture, post-myocardial infarction remodeling and death.

Background: The molecular pathways that regulate the extent of ischemic injury and post-myocardial infarction (MI) remodeling are not well understood. We recently demonstrated that glycogen synthase kinase-3α (GSK-3α) is critical to the heart's response to pressure overload. However, the role, if any, of GSK-3α in regulating ischemic injury and its consequences is not known.

Cytosolic phospholipase A(2)α protects against ischemia/reperfusion injury in the heart.

Studies with sPLA(2) Group X, and cPLA(2) α gene-targeted mice suggest that absence of sPLA(2) Group X results in protection from ischemia/reperfusion (I/R) injury in the heart, and absence of cPLA(2) α Group IV is protective in the brain. Although latter studies might suggest a similar deleterious role for cPLA(2) α in I/R injury in the heart, the pathophysiology of stroke is intricately related to excitotoxicity and cannot necessarily be extrapolated to the heart. We report here that unlike findings in the brain, cPLA(2) α((-/-)) mice have exaggerated injury following I/R in vivo.

Phosphate and calcium are required for TGFbeta-mediated stimulation of ANK expression and function during chondrogenesis.

The expression of ANK, a key player in biomineralization, is stimulated by treatment with TGFbeta. The purpose of this study was to determine whether TGFbeta stimulation of ANK expression during chondrogenesis was dependent upon the influx of calcium and phosphate into cells. Treatment of ATDC5 cells with TGFbeta increased ANK expression during all phases of chondrogenic differentiation, particularly at day 14 (proliferation) and day 32 (mineralizing hypertrophy) of culture.

Oxygen tension regulates the expression of ANK (progressive ankylosis) in an HIF-1-dependent manner in growth plate chondrocytes.

The proximal promoter region of ANK, a gene that codes for a protein that regulates the transport of inorganic pyrophosphate, contains two hypoxia responsive elements (HREs); therefore, we studied the expression and function of ANK at different oxygen tensions. ATDC5 and N1511 clonal chondrocytic cells were cultured in either hypoxia (2% O(2)) or normoxia (21% O(2)). Transcript and protein levels of ANK were depressed in hypoxic conditions, as were levels of extracellular pyrophosphate (ePPi).

Transforming growth factor-beta1 regulates fibronectin isoform expression and splicing factor SRp40 expression during ATDC5 chondrogenic maturation.

Fibronectin (FN) isoform expression is altered during chondrocyte commitment and maturation, with cartilage favoring expression of FN isoforms that includes the type II repeat extra domain B (EDB) but excludes extra domain A (EDA). We and others have hypothesized that the regulated splicing of FN mRNAs is necessary for the progression of chondrogenesis. To test this, we treated the pre-chondrogenic cell line ATDC5 with transforming growth factor-beta1, which has been shown to modulate expression of the EDA and EDB exons, as well as the late markers of chondrocyte maturation; it also slightly accelerates the early acquisition of a sulfated proteoglycan matrix without affecting cell proliferation.

P5L mutation in Ank results in an increase in extracellular inorganic pyrophosphate during proliferation and nonmineralizing hypertrophy in stably transduced ATDC5 cells.

Ank is a multipass transmembrane protein that regulates the cellular transport of inorganic pyrophosphate. In the progressive ankylosis (ank) mouse, a premature termination mutation at glutamic acid 440 results in a phenotype characterized by inappropriate deposition of basic calcium phosphate crystals in skeletal tissues. Mutations in the amino terminus of ANKH, the human homolog of Ank, result in familial calcium pyrophosphate dihydrate deposition disease.

The pleiotropic Arabidopsis frd mutation with altered coordination of chloroplast biogenesis, cell size and differentiation, organ size and number.

In higher plants, plastid development must be tightly coordinated with cell and organ development. In this paper, a novel T-DNA-mutagenized Arabidopsis line showing chlorotic leaves and minute stature was identified in a genetic screen for altered chloroplast development. The mutation corresponded to a single locus on chromosome IV and was associated with insertion of the T-DNA.

New developments in the epidemiology and genetics of gout.

The prevalence of gout appears to be rapidly increasing worldwide and is no longer a disorder suffered primarily by over-fed alcohol consumers. Emerging risk factors include longevity, metabolic syndrome, and new classes of pharmacologic agents. In some ethnic populations, no obvious risk factors can explain the high incidence of hyperuricemia and gout, suggesting a genetic liability.

Role of the progressive ankylosis gene in cartilage mineralization.

Purpose Of Review: Among the myriad of players in the calcification of cartilage, ANK is a relatively new entrant. It is a multipass transmembrane protein that regulates the transport of inorganic pyrophosphate between the cell and the extracellular space. Mutations in ANK result in two distinct calcification disorders: craniometaphyseal dysplasia and familial calcium pyrophosphate dihydrate deposition disease.

Genetics of chondrocalcinosis.

Rapid developments in genetic analysis have enabled the dissection of a variety of arthropathies that are inherited in a Mendelian manner. These disorders include calcium crystal arthropathies such as calcium pyrophosphate dihydrate deposition (CPPD) disease and hydroxyapatite deposition disease. In CPPD disease, mutations in a recently discovered gene, ANKH, have been demonstrated in five affected families and may also be associated with the idiopathic deposition of calcium pyrophosphate dihydrate crystals.

Transforming growth factor-beta1 (TGF-beta1) regulates ATDC5 chondrogenic differentiation and fibronectin isoform expression.

Regulated splicing of fibronectin (FN) occurs during the mesenchymal to chondrocyte transition and ultimately results in the relative enrichment of an extra domain B (EDB) exon-containing FN isoform with the suggestion that FN isoforms may play a functional role in chondrogenesis. Promotion of chondrogenesis can also be achieved by treatment with transforming growth factor-beta (TGF-beta), which also regulates FN isoform expression. We have examined the effects of TGF-beta treatment on the assumption of the chondrogenic phenotype in the teratoma-derived cell line ATDC5 and tested whether these effects on chondrogenesis are paralleled by appropriate changes in FN isoform expression.